(revision no. 1) final report microsemi power mosfet ... · issue date: 26 mar 2007...

ISSUE DATE: 26 MAR 2007 T021907_MSAFX11P50A

TEST REPORT (REVISION NO. 1)

FINAL REPORT

MICROSEMI POWER MOSFET (MSAFX11P50A)

(SINGLE EVENT EFFECTS/SURVIVABILITY)

NAVSEA – Crane Radiation Sciences Branch, Code 6054, B3334

300 Highway 361 Crane IN 47522

Crane P.O.C: Jeffrey L. Titus

(812) 854-1617

NAVSEA Crane Radiation Test Report Report No.: NSWC-MS-MSAFX11P50A-SEE-032607 REVISION: 1

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Document Submission

Originator’s Name Organization Signature Description Date Jeffrey Titus NSWC, Code 6054 Jeffrey Titus Initial Draft Submission 3/26/2007

Approvals Stakeholder Name Organization & Role Signature Date

Document Change Control Rev Date of

Issue Brief Description of Change Change Impact (Pages & Paragraphs)

Modified By


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TABLE OF CONTENTS Section Page 1.0 Executive Summary ........................................................................................................................................................... 1

1.1 Test Results Summary.................................................................................................................................................... 1 2.0 Background ........................................................................................................................................................................ 2 3.0 References .......................................................................................................................................................................... 2 4.0 Handling Precautions ......................................................................................................................................................... 2 5.0 Visual Inspection................................................................................................................................................................ 3 6.0 Procedure............................................................................................................................................................................ 3 7.0 Single Event Effect Survivability/Characterization Test.................................................................................................... 5

7.1 Bias Circuit..................................................................................................................................................................... 6 7.2 Dosimetry ....................................................................................................................................................................... 7 7.3 Beam Uniformity............................................................................................................................................................ 8 7.4 Axial Gain, Flux, and Fluence Measurements................................................................................................................ 9 7.5 Beam Energy .................................................................................................................................................................. 9 7.6 In-Air Test Platform ....................................................................................................................................................... 9 7.7 Beam Conditions .......................................................................................................................................................... 10 7.8 SEU Test Results.......................................................................................................................................................... 10

7.8.1 Krypton Test Results ............................................................................................................................................. 11 7.8.2 Xenon Test Results................................................................................................................................................ 12 7.8.3 Argon Test Results ................................................................................................................................................ 13

7.9 Device Physics ............................................................................................................................................................. 13 7.9.1 Background Doping............................................................................................................................................... 13 7.9.2 Depletion Layer Width .......................................................................................................................................... 13 7.9.3 Estimated SEE Cross Section ................................................................................................................................ 14 7.9.4 Estimated Gate Oxide Thickness and Computed Critical Voltages for Various Ions ........................................... 15 7.9.5 Device Layer and Thickness Analysis................................................................................................................... 16 7.9.6 Lethal Ion Rate (LIR) Calculations ....................................................................................................................... 18

8.0 Summary .......................................................................................................................................................................... 20 Appendix A: LET and Range Curves of Each Ion Tested..................................................................................................... 23

A1.0 Krypton..................................................................................................................................................................... 23 A2.0 Xenon ....................................................................................................................................................................... 24 A3.0 Argon........................................................................................................................................................................ 25

Appendix B: Texas A&M Dosimetry and Shot Log (Flux, Uniformity, Energy, LET, Etc.)................................................ 26 B1.0 Argon........................................................................................................................................................................ 26 B2.0 Krypton..................................................................................................................................................................... 27 B3.0 Xenon........................................................................................................................................................................ 31

Appendix C: Experimenters Shot and Bias Log Sheets ........................................................................................................ 32 C1.0 Krypton..................................................................................................................................................................... 32 C2.0 Xenon........................................................................................................................................................................ 37 C3.0 Argon........................................................................................................................................................................ 38

Appendix D – Recorded/Monitored Drain and Gate Current................................................................................................. 39 Appendix E: Notes and Setup Information........................................................................................................................... 40 Appendix F: Acronyms ......................................................................................................................................................... 41


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Program: Report Date:

Power MOSFET Radiation Characterization 03/26/2007 Generic Part No. Part Description: Manufacturer:

MSAFX11P50A 500-V, P-Channel, Power MOSFET Microsemi (MS) Package Type: Date Code: Wafer Lot No:

COOLPACK1 0844 Detailed Test Specification: General Test Requirement: Performance Specification

NASA Test Request NASA Test Request Microsemi Datasheet #MSC0308A Serial Number: Radiation Test Test Date

SN 1-10 SEU 02/19/2007-02/20/2007 1.0 Executive Summary

During the period from 19 February 2007 to 20 February 2007, NAVSEA Crane evaluated the radiation performance of a -500-Volt, -11-Ampere, 750 mOhm, P-channel power metal-oxide semiconductor field-effect transistor (MOSFET), the MSAFX11P50A, to single event effects (SEE) survivability, a heavy ion test environment, as requested by Christian Poivey (NASA). In this report, Section 6 details the characterization procedure; Section 7 discusses specific test details; Section 8 presents the test results; Appendix A shows linear energy transfer (LET) and range curves for each ion tested; Appendix B is a summary of the Texas A&M Dosimetry for each run; Appendix C presents a shot log for the device under test (DUT); Appendix D shows plotted drain and gate currents during Krypton, Xenon, and Argon irradiation; Appendix E provides test setup notes; and Appendix F provides a list of useful acronyms and definitions

1.1 Test Results Summary Ten (10) packages were characterized in accordance with the NASA test request. Five of the ten packages were irradiated using 1858-MeV Krypton (LET=20.6 MeV/mg/cm2 and Range=284 μm). One of those five packages was also irradiated with 860-MeV Krypton (LET=30 MeV/mg/cm2 and Range=108 μm). Three devices were irradiated with 2758-MeV Xenon (LET=40.7 and Range=237 um). The last two devices were irradiated with 929-MeV Argon (LET=5.7 and Range=445 um). Table 1 provides an SEE test summary.

Table 1. SEE Test Summary


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From the SEE data, the dominant failure mode was identified as single-event gate rupture (SEGR). The data strongly suggest that device operation at VGS < 10V and VDS < –300V (upper limit) provides a relative safe operating region when irradiated with Krypton (Kr) and Argon (Ar). In a real space environment, the abundance (or fluence) of heavy ions diminishes rapidly above iron (Fe). Therefore, krypton represents an upper boundary of concern for most space applications. Above Kr, the data suggest that device operation of VGS<5V and VDS<-100V should provide an upper boundary for ions less than Xe. There was a significant decrease in the device operational voltages between krypton and xenon. Statistical models should be applied to ensure that the probability of failure is within acceptable limits and confidence levels (a simple example is provided in section 7.9.6). The mean-time-to-failure (MTTF) for this device is several years under the conditions used in our example. Finally, although rare in p-channel devices, this device exhibited what appears to be single-event burnout (SEB) when irradiated with Argon. This would suggest that the devices’ secondary breakdown voltages (drain-to-source voltage) are between 480 and 500 volts. For reference on this mechanism, I would suggest a paper published in the IEEE Transaction on Nuclear Science, vol.53, Dec. 2006, pp.3379-3385. Outside this funded project, we may examine the response of the p-channel devices using simulations. We will submit this additional work, if completed, for presentation and publication.

2.0 Background Microsemi packages and markets the MSAFX11P50A; however, Microsemi does not fabricate the actual die (Microsemi purchases die from a different manufacturer and then assembles them). NASA provided a limited number of test samples. This SEE characterization should identify most potential problems with this device and provide a baseline of its SEE radiation performance per the NASA test request.

3.0 References The major applicable documents, used to perform this SEE/survivability characterization are:

MIL-PRF-19500 General Specifications for Semiconductor Devices MIL-STD-750D Test Method Standard Semiconductor Devices ASTM Standard E668 Standard Practice for the Application of Thermoluminescence

Dosimetry (TLD) Systems for Determining Absorbed Dose in Radiation Hardness Testing of Electronic Devices - Annual Book of ASTM Standards, Vol. 12.02: Nuclear (II), Solar, and Geothermal Energy, American Society for Testing and Materials

NAVSEA INST 4734.1 NAVSEA Metrology and Calibration Program DOD-HDBK-263 Handbook - Electrostatic discharge sensitive devices NSWC C6054-

4.0 Handling Precautions

Handling precautions were observed in accordance with DOD-HDBK-263, specifically regarding the handling of electrostatic discharge (ESD) sensitive devices. These include: 1. Maximum rated voltages during irradiation were not exceeded 2. Devices were stored within antistatic boxes and conductive foam 3. Devices were not handled by leads (minimized wherever possible)


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5.0 Visual Inspection We performed a quick visual inspection (naked eye) of each package. Devices scheduled for heavy ion testing had their lids removed and each of these packages were examined under a low power microscope to ensure that bond wires were still intact and the exposed die had no visible signs of debris or other issues that might interfere with the testing. These devices were then soldered to a TO-3 type daughter card (test sockets were not readily available and lead times exceeded test schedule) providing an interface that was readily available for these tests.

6.0 Procedure Tests were performed as requested by the NASA test Request (emails from Christian Poivey), using an applicable test circuit. Irradiations were performed at ambient room temperature (22°C ± 5°C). The following steps were followed: 1. The DUT board was mounted to the open-air mounting frame. Two 40-Pin ribbon cables were

connected to the test board and switch box (each cable was 22 ft in length). The switch box allowed the user to select between 18 different socket positions. Two triax cables were connected between the Keithley source measurement units and the switch box. Socket connections were then verified.

2. Using the single event upset system supervisor (SEUSS) software, each socket was aligned

with the beam-line laser and each position centered (beam was centered to exposed die). Each socket position (x, y and z coordinates) was stored. Z was fixed to maintain an air gap distance of 5 cm between the beam exit port and the die surface. This air gap distance was determined using a laser-mounted, electronic caliper. This technique provided measurements within (+/−) 0.1 cm. For these ions and beam energies, this error was negligible. After all the positions were stored, the software interface allowed each stored socket position to be recalled. This interface allowed me to easily change from one test socket to the next without breaking the interlock system (overall this technique saves approximately 5 to 10 minutes for each device that doesn’t require a DUT change).

3. With the board power disabled, the test board was removed and the test devices inserted into

their appropriate sockets. The test board was designed to test six different device types with three sockets allocated to each device type. The socket arrangement and designated device types were (note that the bolded socket positions represent the device type in this report):

1. Socket 1: MSAFX11P50A (X=-2.725 in; Y=-2.545 in; Z=-8.417 in) 2. Socket 2: MSAFX11P50A (X=-1.451 in; Y=-2.545 in; Z=-8.417 in) 3. Socket 3: MSAFX11P50A (X=-0.063 in; Y=-2.545 in; Z=-8.417 in) 4. Socket 4: MSAFX11P50A (X=+1.412 in; Y=-2.545 in; Z=-8.417 in) 5. Socket 5: MSAFX11P50A (X=+2.812 in; Y=-2.545 in; Z=-8.417 in) 6. Socket 6: (X=+4.067 in; Y=-2.545 in; Z=-8.417 in) 7. Socket 7: (X=-2.740 in; Y=-0.174 in; Z=-8.417 in) 8. Socket 8: (X=-1.441 in; Y=-0.205 in; Z=-8.417 in) 9. Socket 9: (X=-0.092 in; Y=-0.205 in; Z=-8.417 in) 10. Socket 10: (X=+1.383 in; Y=-0.205 in; Z=-8.417 in) 11. Socket 11: (X=+2.808 in; Y=-0.205 in; Z=-8.417 in) 12. Socket 12: (X=+4.282 in; Y=-0.205 in; Z=-8.417 in)


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4. Ion Species and Characteristics: • Krypton was the first ion species used. At 25 MeV/amu, the initial beam energy was 1971

MeV. The air gap (5 cm) along with the selected beam degraders reduced the ion energy at the die surface to approximately 1858 MeV. This resulted in an LET of approximately 20.6 MeV/mg/cm2 with a range of 284.4 μm. This LET and range should fully penetrate the active volume.

• Xenon was the second ion species used. At 25 MeV/amu, the initial beam energy was 1935

MeV. The air gap (5 cm) along with selected beam degraders reduced the ion energy at the die surface to approximately 2758 MeV. This resulted in an LET of approximately 40.7 MeV/mg/cm2 with a range of 237.7 μm. This LET and range should fully penetrate the active volume.

• Argon was the third ion species used. At 25 MeV/amu, the initial beam energy was 1000-

MeV. The air gap (5 cm) along with selected beam degraders reduced the ion energy at the die surface to approximately 929 MeV. This resulted in an LET of approximately 5.7 MeV/mg/cm2 with a range of 445 μm. This LET and range should fully penetrate the active volume.

5. With the ion beam shuttered (a technique where a beam stop is inserted into the beam line

preventing the flow of ions), the positional table was moved to Socket 1. Maximum beam fluence was set to 106 ions/cm2. Beam flux was adjusted to approximately 2x104 ion/cm2/s. Beam flux is not a controlled parameter and varies during irradiations.

6. Available sample sizes for test were small (ten test samples). Note that the occurrence of a

single event in these types of devices is typically destructive. Therefore, this SEE characterization was designed to define safe operating conditions rather than obtain a large statistical number of errors. Identification of the failure thresholds for a given ion at different bias conditions bounds the safe operating area. Then, the SEE cross sectional curve can be represented as a step function where the saturated cross section is estimated from the die area (a value of 30% of die area for single event gate rupture (SEGR) to 80% for single event burnout (SEB) is typically a good estimate – this is based upon criteria from numerous published technical papers).

7. To obtain safe operating conditions and minimize failure, the initial gate voltage was set to zero

volts and the drain voltage was set to -100 volts. The drain and gate currents were monitored at all times to determine if failure occurred. Just before irradiation, a pre-irradiation screen was performed. The beam stop was removed and the irradiation sequence was started. During irradiation, the gate and drain currents were recorded and monitored for any signs of SEE-induced failure (I failed to initiate the log file for this first device and that data was not saved but the devices tested thereafter saved the data). When the fluence reached 106 ions/cm2, the beam stop was inserted (shuttering the beam). This terminated the test sequence. After shuttering the beam, a post-irradiation screen was performed. The post-screen test applied a gate voltage of 20 volts and a drain voltage of -250 volts (except for the first device where not post-gate stress test was performed). If damaged, this screen should cause the drain or gate current to increase sharply.


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8. If no SEE damage was noted, the drain bias was incremented by –20 or -25 volts and the test sequence repeated. This process was repeated until an SEE failure occurred or until the end of the test sequence where the drain voltage was set to the device’s rated breakdown of -500 volts. Another test sequence was to fix the drain voltage at –250 or –300 volts, and increment the gate voltage in 2-volt steps until the gate bias reached 12 volts. For each test sequence, the device type, run number, socket number, tilt/angle of the board, serial number, applied gate voltage, applied drain voltage, ion, ion energy, flux, and fluence were recorded.

9. If SEE failure occurred, the positional stage was moved to the next device on the test board and

characterized to that ion using voltages below the observed failure threshold to ensure safe operating conditions with multiple samples.

10. Before irradiation with the next ion species, devices that failed during the previous test were

removed and replaced with the next available test sample and the process repeated.

7.0 Single Event Effect Survivability/Characterization Test Systems subjected to a continuous bombardment of omni-directional radiation from protons, electrons, and heavy ions can present potential problems to on-board electronics, and especially devices that are prone to catastrophic failure. Power MOSFETs can exhibit SEB and/or SEGR when excited by a heavy ion striking a sensitive region while operating above a critical operating voltage. If either failure mode is initiated, it can result in catastrophic device failure. Typical MOSFET structures are shown in Figure 1a (hexagonal structure or closed cell geometry) and Figure 1b (stripe structure or open cell geometry). Both structures have been described and discussed in the published literature (see IEEE TNS). Although p-channel devices are considered SEB insensitive when compared to their n-channel counterparts, they are not immune to SEB. Both N- and P-channel devices are prone to SEGR. SEE survivability characterizations were performed at the Texas A&M cyclotron institute. Device currents were monitored to detect SEB and/or SEGR. The device structures (die photo and cross sections) are shown in Figs. 10-14.

Fig. 1a. Hexagonal structure Fig. 1b. Stripe structure


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7.1 Bias Circuit A custom test board (SEGR Test System Board - DUT Interface Board) was designed and fabricated to perform this SEE/survivability characterization. The test circuit conformed to the requirements of the NASA Test Request referenced in Section 3.0. Figure 2 below depicts the SEE/survivability test circuit defined by the test plan referenced in Section 3.0. This circuit was used to monitor the drain and gate currents before, during, and after the electron pulse. Although the test circuit interfered with the quality of the subthreshold and breakdown voltage sweeps, these were performed periodically to verify device functionality.

Fig. 2. Schematic Representation of SEE Survivability Test Circuit

The gate circuitry employed two Keithley 237 Source Measurement Units (SMU) connected to a switch box via triax cable, which was then connected to the test board thru two 40-pin ribbon cables. At the board, the gate node of each socket employed two 220-ohm resistors with a ceramic 0.01-μF capacitor to ground. This circuitry was employed to filter and dampen noise presented to the gate during testing. The drain circuitry also employed a Keithley 237 SMU connected to the switch box via triax cable, which was then connected to the test board thru 40-pin ribbon cables. The drain node of each socket employed ceramic stiffening capacitors (total of .1 μF). Figure 3 shows photos of the fabricated test board. Cabling and equipment setup details are provided in Appendix E.


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Front of Board Back of Board

Fig. 3. Top- and back-side photographs of SEE test board.

7.2 Dosimetry

Dosimetry was provided by the Texas A&M heavy ion test facility. The following details were reproduced from information provided by the test facility. Beams can be delivered with a high degree of uniformity over a 1-inch diameter circular cross sectional area using the in-air test system. Uniformity is achieved by magnetic defocusing and by thin foil scattering. The beam uniformity and flux are determined using an array of five plastic scintillators coupled to photo multiplier tubes, located in the diagnostic chamber adjacent to and upstream from the target. Four of the five detectors are fixed in position and set up to measure beam particle counting rates continuously at four characteristic points - 1.64 inches (4.71 mm) away from the beam axis center. The fifth scintillator is inserted to measure the beam particle counting rate right at the beam axis and is removed to provide an unobstructed beam during testing. Figure 4 shows a drawing of the scintillator arrangement. A 0.1-cm2 aperture defines the sensitive area of each detector, while the intrinsic efficiency is 100% for all practical purposes. The control software determines the beam uniformity (ranging from 0 to 100%), axial gain (%), and beam flux (in particles/cm2/s) based on the scintillator counting rates. The parameters are displayed on the computer screen and are updated once every second


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Fig. 4. Scintillator Arrangement Used in Heavy Ion Dosimetry

7.3 Beam Uniformity

Details about beam uniformity are reproduced from information provided by the Texas A&M cyclotron test facility. Equation 1 determines beam uniformity.

av

avBRavTRavBLavTL

nnnnnnnnn

uniformity

3)()()()(1

100(%)2222 −+−+−+−

+

= (1)

where TLn count for top left scintillator

BLn count for bottom left scintillator

TRn count for top right scintillator

BRn count for bottom right scintillator

avn Average count of all four scintillators

Another quantity used to gauge beam uniformity is the central shift. The central shift is a percentage of how far the beam is off from the central beam axis. Eq. 2 is used to calculate central shift.

%1002

(%)

22

xn

nnnnn

nnnn

shiftcentral i

BRBLTRTL

i

BRTRBLTL⎟⎟⎠

⎞⎜⎜⎝

⎛ −−++⎟⎟

⎠

⎞⎜⎜⎝

⎛ −−+

=∑∑

(2)

where in (i = BL, BR, TL, TR).


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7.4 Axial Gain, Flux, and Fluence Measurements The facility software, SEUSS, calculates the axial gain of the beam using Equation 3:

4)( TLTRBLTL

centernnnn

ngainaxial+++

= (3)

where ncenter is the count from the center scintillator. SEUSS then uses the last value recorded from the center detector before it is removed to calculate the axial gain during run time. When the center scintillator is removed, the center count rate is determined by averaging the rate of the four remaining detectors. The implied beam flux is determined using Equation 4:

)()//( 2 gainaxialxA

Ncmsparticlesflux center= (4)

where Ncenter is the implied count rate of the center scintillator A is the surface area of the detector (A = 0.1 cm2)

The flux is calculated every second. The incremental fluence, or total particle count per unit area, is determined by applying Equation 5.

sec1xfluxfluencelIncrementa = (5)

The incremental fluence for a specific run is calculated each second, with the total fluence of the run being the sum of the incremental fluence. Equation 6 represents this calculation.

∑=

=n

ttRUN fluencelIncrementafluence

1)( (6)

7.5 Beam Energy In addition to the scintillators, a 1-mm thick silicon surface barrier detector located in one of the upstream diagnostic chambers is used to measure the beam particle total energy and to provide information on beam purity. It can also be used to measure the energy and the energy straggle of the beam coming out of the degrader foils.

7.6 In-Air Test Platform

Texas A&M provides the in-air test platform. The in-air test platform consists of an x-y-z positional stage with clockwise and counter-clockwise rotation capability to 90 degrees, which is computer controllable. Figure 5 shows a photograph of the beam exit port and positioning stage. The mounting frame has the same dimensions as the in-vacuum mounting frame. An electronic caliper is used to determine the air gap between the device under test and beam exit port. This air gap becomes a degrader, reducing the beam energy before its interaction with the device under test (our air gap was 5 cm). At these higher energies, small errors in the actual air gap measurement are inconsequential.


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Fig. 5. Photograph of In-Air Test Platform Showing Beam Exit Port; Top of Positioning Stage; and Mounting Frame with board and DUTs mounted

7.7 Beam Conditions

Test personnel used the open-air test system with a measured air gap between the exit port and the die of 5 cm. The beam flux was nominally set between 104 to 3x104 ions/cm2/s. Beam flux does not remain constant during an exposure run and fluctuates up and down with a tendency to slowly decrease in intensity. The fluence was programmed at 106 ions/cm2. SEUSS automatically shutters the ion beam when the programmed fluence is achieved. Three different ion species (Krypton, Xenon, and Argon) were employed with beam energies of 25 MeV/amu.

7.8 SEU Test Results

Ten packages were characterized in accordance with the NASA test request. Five of the ten packages were irradiated using Krypton (incident LET=20.6 MeV/mg/cm2). Minimum applied drain biases for two different gate voltages that failed Krypton irradiation were (VGS =0V; VDS =-420 V) and (VGS = 11 V; VDS = -300 V). Figure 6 shows overlaid plots of the drain current monitored during various runs (Fig. 6a shows SN 2 while Fig. 6b shows SN 3). The drain current increases drastically once SEE failure occurs. Three of the remaining packages that were not taken to failure were then irradiated to 2758-MeV Xenon (incident LET=40.7 MeV/mg/cm2). Maximum applied drain biases that passed Xenon irradiation were (VGS = 0 V; VDS = −100 V). We also performed a gate bias test that passed at (VDS = 0 V; VGS = 46 V). The two remaining packages were irradiated to 929-MeV Argon (incident LET= 5.7 MeV/mg/cm2). Maximum applied drain


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biases that passed Argon irradiation were (VGS = 0 V; VDS = -480 V). Both devices were taken to failure and failed at the same point. These SEE failures exhibited SEB type behavior whereas the previous devices exhibited SEGR type failure. We believe this behavior suggest that the secondary breakdown voltage of this device is between –480 and 500V. This would suggest that the device is susceptible to burnout behavior above –480V with sufficient current density to directly initiate secondary breakdown. Figs. 7, 8, and 9 provide graphical summaries of the last passing and first failing biases for Krypton, Xenon, and Argon, respectively. Readings represent 1 second intervals. 7.8.1 Krypton Test Results

Fig. 6a. Monitored drain and gate currents of SN 2 during exposure to Krypton. Drain and gate currents were recorded just before beam, during beam and just after shuttering the beam. Measurements were taken every second. From these recorded currents, the onset of failure can be easily identified. Runs 19 to Run 22 show no evidence of SEB or SEGR; however, during Run 23, the drain and gate current increases drastically shortly after the shutter was removed and irradiation initiated.

Fig. 6b. Monitored drain and gate currents of SN 3 during exposure to Krypton. Drain and gate currents were recorded just before beam, during beam and just after shuttering the beam. Measurements were taken every second. From these recorded currents, the onset of failure can be easily identified. Runs 24 to Run 35 show no evidence of SEB or SEGR; however, during Run 36, the drain and gate current increases drastically shortly after the shutter was removed and irradiation initiated.


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Fig. 7. Krypton Test Results showing last passing and first failing biases. Safe operating area is only based upon this ion condition.

7.8.2 Xenon Test Results

Fig. 8. Xenon Test Results showing last passing and first failing biases


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7.8.3 Argon Test Results

Fig. 9. Argon Test Results showing last passing and first failing biases

7.9 Device Physics For this device, we estimated the covering layers to be 7 μm and calculated the epitaxial layer thickness to be 50 μm (see 7.9.1 and 7.9.2). SRIM 2003 was used to compute LET and range curves for each ion (see Appendix A). Based upon this information, the ion energy was selected to optimize energy deposition within these layers and total ion penetration.

7.9.1 Background Doping

A first order approximation of the background doping (doping of the epitaxial layer) was calculated by using Eq. 7.

3/44/318 )1077.1(⎥⎦

⎤⎢⎣

⎡=

DSSB BV

xN (7)

Where: NB = Background Doping (cm-3) BVDSS = Drain-to-Source Breakdown Voltage (V) 1.77x1018 = Constant

For these devices, the breakdown voltage, BVDSS, was assumed to be 550 volts yielding a calculated NB value of 4x1014 cm-3.

7.9.2 Depletion Layer Width

A first order approximation of the depletion layer width (how far the depletion field extends into the epitaxial layer for a given drain bias) was estimated by using Equation 8.


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)()()()()()2(

B

DSoSi

NqV

Wεκ

= (8)

Where: W = Depletion Layer Width (cm) εο = Permitivity constant in vacuum (8.854x10-14 F/cm) κSi = Dielectric Constant of Silicon (11.9) VDS = Drain to Source Voltage (V) q = Electronic Charge (eV) NB = Background Doping (cm-3)

We calculated the maximum depletion width, W, at the device’s breakdown voltage, BVDSS. The maximum depletion width provides a good estimate of the epitaxial layer thickness under the n-body diffusion. For these devices, we calculated this to be 43 μm. We assumed the n-body diffusion to be 4 to 6 μm; therefore, the total epitaxial layer should be about 50 μm.

7.9.3 Estimated SEE Cross Section

The total sensitive area is assumed to be 35% of the die area for SEGR and 80% for SEB. This ratio should provide a good approximation of the saturated SEE cross-sectional areas. Figure 10 is a die photo of the MSAFX11P50A. Die dimensions are 0.350 in by 0.280 in yielding a die area of 0.632 cm2. Die dimensions were measured using an optical microscope with a micrometer. Cell layout is composed of oblong cells placed orthogonal to each other.

Fig. 10. Die photograph of an MSAFX11P50A (die dimensions: 0.350 in x 0.280 in)

Using the measured die area of 0.632 cm2, the saturated SEGR cross-sectional area should be between 0.19 and 0.38 cm2 and the saturated SEB cross section should be between 0.38 and 0.51 cm2.


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7.9.4 Estimated Gate Oxide Thickness and Computed Critical Voltages for Various Ions We computed the oxide thickness to be 1050A from the Xe data where the critical gate voltage was measured at 47V (VGS=47V and VDS=0V) and by applying the Titus-Wheatley equation reproduced here for reference (see equation 9).

⎟⎟⎟⎟

⎠

⎞

⎜⎜⎜⎜

⎝

⎛

+=

441

*_ Z

TEV OXBR

CRITGS (9)

Using the Titus-Wheatley equation and this computed value for the gate oxide thickness, we estimated the critical gate voltage to induce SEGR for different ions, where EBR is the dielectric breakdown (1E7 V/cm) field and TOX is the gate oxide thickness Those critical gate voltages are shown in Table II.

Table II. Summary of Computed Critical Values of VGS


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7.9.5 Device Layer and Thickness Analysis We cleaved the device (perpendicular to the die surface), potted, polished, and stained the sample to better define the different device regions. Figure 11 shows a photograph obtained using the scanning electron microscope (SEM). Here, we measured the source metallization at approximately 4 μm; the metal isolation oxide at approximately 1.29 μm; the polysilicon at approximately 0.6 μm; and the polysilicon isolation oxide at approximately 0.87 μm.

Fig. 11. SEM photograph of the top covering layers (note the bottom of the photograph represents the top metallization layer).

Figs. 12-14 show photographs obtained using a high-power microscope after the sample was polished and stained. From these photographs, we determined an epitaxial layer thickness of approximately 45 μm and a p-body thickness of approximately 5 μm using the source metallization as our reference point.


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Fig. 12. Microscope photograph of the MOSFET (showing entire wafer thickness) after polish and stain.

Fig. 13. Microscope photograph (at higher magnification) of the MOSFET (showing the top layers and epitaxial layer) after polish and stain.


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Fig. 14. Microscope photograph (at even higher magnification) of the MOSFET (showing top layers) after polish and stain.

7.9.6 Lethal Ion Rate (LIR) Calculations

To define the lethal ion rate (LIR), the following steps are applied: (a) Define the hazard: This is the orbital conditions in which the device will be

subjected and expressed as an integral flux curve as a function of LET (b) Define the operating conditions: This is the operating conditions of the system

application and includes the on-off time. (c) Define the SEGR sensitivity: This is based upon the SEGR failure thresholds

and the SEGR sensitive area of the device. (d) Define critical LET: This represents the critical Let and SSA for each solid angle

segment. (e) Define the integral flux points: For each critical LET, a integral flux point will

be established (f) Define the LIR: using a piecewise linear approach sum all the points for all

conditions (g) Predict Time to Failure: Compute the time to failure.

7.9.6.1 Hazard Definition

Defining the hazard requires detailed information about the environment in which the system will be flown (orbital information, etc). This information is not available. Therefore, as a definition example (only shown as an example), we selected an international space station hazard using CREME96. Fig. 15 shows the integral flux curve as a function of LET.


19

Fig. 15. Hazard definition example for the International Space Station (ISS) generated from CRÈME96 for ions with atomic numbers from 1 to 92 during solar peak conditions using 100 mils of aluminum shielding.

7.9.6.2 Operating Condition Definition

Defining the operating condition requires detailed information about the actual system application of the selected device (Bias, duty cycle, etc.). This information is not available. Therefore, as a definition example, we will assume that the device is operating under the following conditions (VDS=240V and 100% off-state duty cycle).

7.9.6.3 SEGR Sensitivity Definition Defining the SEGR sensitivity requires detailed information about the SEGR failure threshold response over many different ions (SEGR Signature Curves). A limited data set was taken at Texas A&M to provide a crude SEGR Signature Curve. To define a good SEGR signature curve requires the irradiation of several devices (>50 devices) using many different ions.

7.9.6.4 Critical LET Definition From these SEGR signature curves, one would then determine a critical LET and SSA value (we assumed that the SSA is 0.2212 cm2 or 35% of die area) for a set of solid angles (for SEGR, the failure threshold increases as the solid angle increases). For this example, we will assume that the response remains the same to an angle of 30 degrees (1.2254 sr) and no failures occur above this angle.


20

7.9.6.5 Integral Flux Points Definition For each critical LET value, an integral flux point is extracted from the hazard definition curve (each point represents a bias, angle, orbit condition, etc.). This defines the flux of lethal ions available.

7.9.6.6 LIR Definition Using a piecewise linear approach, sum all the points for all conditions (LIR = [(SSA) x [(FV1)(Φ1)(φ1) + (FV2)(Φ2)(φ2) + ….]]. For our simplified example, we used only two points for our LIR definition using an integral flux (ΦINT) of 2.3E-8 (LET>40) and 1E-8 (LET>51); a solid angle of 0.4282 and 1.2554 sr; 100% time fraction (VF1); and a SSA of 0.2212 cm2 yielding a LIR of 4.955E-9.

7.9.6.7 VEF Prediction Once the LIR is established, the time to failure (very early time to failure) can be computed applying the mathematical expression:

])1

[)]1ln([)],([)(LIRN

iclifit −−= where )( 72.0)ln(),(

−−= iclclif

Using this methodology, we estimated the time of very early failure (VEF) of two devices (N=2). Table III provides a summary of those estimated VEF using different confidence levels. Note that the Mean-time-to-Failure (MTTF) is represented using a CL of 0.368. Table III. Estimated VEF for differ4ent confidence levels (MTTF is equal to cl=0.368)

Orbit Shield CL VEFThickness (days)

ISS 100 mils 0.99 16.26ISS 100 mils 0.9 170.42ISS 100 mils 0.368 1616.92

Of course, this is just a rough approximation for the time for VEF to occur for this example. There are many variables that will influence these predicted failure times such as shielding, duty cycle time, the defined hazard (we used solar peak conditions which are very severe comnpared to non-peak conditions); etc.. If device operation limits the drain voltage to 110V, then the device should be relatively safe from any SEGR events. Biases between 110V and 400V (VGS=0V) would be expected to have some probability of device failure as indicated here – as the voltage is decreased from 400V to 110V, the time required for VEF will increase.

8.0 Summary

In evaluating the radiation performance of this -500V, -11A, P-channel power MOSFET (MSAFX11P50A), a total of ten devices (S/N’s 1-10) were characterized to a heavy ion environment at Texas A&M cyclotron institute. Experiment objectives were to characterize these devices in this environment (SOA definition is limited by the number of available test samples) and to define a limited failure threshold curve (failure threshold curve is again limited by the number of


21

test samples expended in test since each defined point results in a device failure). Five of the ten packages were irradiated using 1858-MeV Krypton (LET=20.6 MeV/mg/cm2 and Range=284 μm). One of these five packages was irradiated with 860-MeV Krypton (LET=30 MeV/mg/cm2 and Range=108 μm). Three devices were irradiated with 2758-MeV Xenon (LET=40.7 and Range=237 um). The last two devices were irradiated with 929-MeV Argon (LET=5.7 and Range=445 um). An SEE test summary is provided in Table IV:

Table IV. SEE Test Summary

From these data, the dominant failure mode appears to be single-event gate rupture (SEGR). These data strongly suggest that device operation at VGS < 10V and VDS < –300V (upper limit) provides a safe operating area when irradiated with Krypton (Kr) and Argon (Ar). In a real space environment, the abundance (or fluence) of heavy ions diminishes rapidly above iron (Fe). Therefore, krypton represents an upper boundary of concern for most space applications. Above Kr, these data suggest that device operation of VGS<5V and VDS<-100V should provide an upper boundary for ion less than Xe. There is a significant decrease in the device operational voltages with ions above Xenon. Statistical models should be applied to ensure that the probability of failure is within acceptable limits and confidence levels. Finally, although rare in p-channel devices, this device exhibited a single event burnout (SEB) type failure when irradiated with Argon. This would suggest that the devices’ secondary breakdown voltages (drain-to-source voltage) are between 480 and 500 volts. For reference on this mechanism, I would suggest a paper published in the IEEE Transaction on Nuclear Science, vol.53, Dec. 2006, pp.3379-3385. Outside this funded project, we may examine the response of p-channel devices using simulations. This additional work, if completed, will be submitted for presentation and publication.


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Suitability of these devices for a given system application is not defined in this test report and is beyond the scope of this test. However, the data contained within this report can be used as inputs to determine the risk of device failure for a given application and environment. Risk assessment techniques are available in the published literature (also see example in section 7.9). To ensure safer operation, the operating conditions of the system application should not exceed the safe operating biases for the ions of interest. Note that in most cases the failure mode of power MOSFETs cannot be defined using effective LET and that worse case is usually represented by an ion that strikes perpendicular to the die surface with maximum deposition with total ion penetration in the active layers.


23

Appendix A: LET and Range Curves of Each Ion Tested The figures in this Appendix show LET and range as a function of energy for Krypton, Xenon, and Argon. These data were computed using the software code, SRIM 2003. A1.0 Krypton

Figure A1: Krypton LET and Range Curve

Testing was performed at an incident beam energy of 1858 MeV and 860 MeV (a very limited data set at this energy). These data show that the incident LET of 1858-MeV Krypton is approximately 20.6 MeV/(mg/cm2). At this energy, the LET rises as the ion sheds energy to the target material until the energy reaches approximately 185 MeV. As the ion continues its path and sheds more energy, the LET decreases and continues to do so until it comes to rest. A typical 500-Volt power MOSFET will have approximately 7 μm of layers including the gate oxide covering the active epitaxial layer, which is approximately 50 μm. Therefore, an 860-MeV ion energy comes close to optimizing the energy deposition within all these layers and should produce the lowest failure threshold for Krypton if there is a dependency upon the ion energy. At 1858, the averaged LET distribution within the epitaxial layer is approximately 22 MeV/(mg/cm2). At 860, the averaged LET distribution within the epitaxial layer is approximately 35 MeV/(mg/cm2).


24

A2.0 Xenon

Figure A2: Xenon LET and Range Curve

Testing was performed at the incident beam energy of 2758 MeV. These data show that the incident LET of 2758-MeV Xenon is approximately 40.7 MeV/(mg/cm2). At this energy, the LET rises as the ion sheds energy to the target material until the energy reaches approximately 500 MeV. As the ion continues its path and sheds more energy, the LET decreases and continues to do so until it comes to rest. A typical 500-Volt power MOSFET will have approximately 7 μm of layers including the gate oxide covering the active epitaxial layer, which is approximately 50 μm. The averaged LET distribution within the epitaxial layer is approximately 46 MeV/(mg/cm2).


25

A3.0 Argon

Figure A3: Argon LET and Range Curve

Testing was performed at the incident beam energy of 929 MeV. These data show that the incident LET of 929-MeV Gold is approximately 5.7 MeV/(mg/cm2). At this energy, the LET rises as the ion sheds energy to the target material until the energy reaches approximately 45 MeV (peaking at an LET value of 18.65). As the ion continues its path and sheds more energy, the LET decreases and continues to do so until it comes to rest. A typical 500-Volt power MOSFET will have approximately 7 μm of layers including the gate oxide covering the active epitaxial layer (the epitaxial layer is approximately 50 μm). For this device, the energy distribution over this range is highlighted in yellow in Fig. A3. The averaged LET distribution within the epitaxial layer is approximately 5.8 MeV/(mg/cm2).


26

Appendix B: Texas A&M Dosimetry and Shot Log (Flux, Uniformity, Energy, LET, Etc.) B1.0 Argon

Run File Test Run Ion Ion Initial No. Ext Date Time Beam MeV/u Energy LET Range 179 #b7 2/20/2007 2:56:27 Ar 24.8 929 5.7 445.4 180 #b8 2/20/2007 2:57:52 Ar 24.8 929 5.7 445.4 181 #b9 2/20/2007 2:59:03 Ar 24.8 929 5.7 445.4 182 #ba 2/20/2007 3:00:10 Ar 24.8 929 5.7 445.4 183 #bb 2/20/2007 3:01:24 Ar 24.8 929 5.7 445.4 184 #bc 2/20/2007 3:02:35 Ar 24.8 929 5.7 445.4 185 #bd 2/20/2007 3:07:35 Ar 24.8 929 5.7 445.4 186 #be 2/20/2007 3:08:43 Ar 24.8 929 5.7 445.4 187 #bf 2/20/2007 3:09:45 Ar 24.8 929 5.7 445.4 188 #bg 2/20/2007 3:11:00 Ar 24.8 929 5.7 445.4 189 #bh 2/20/2007 3:12:07 Ar 24.8 929 5.7 445.4 190 #bi 2/20/2007 3:13:08 Ar 24.8 929 5.7 445.4

Run Ion Ion Flux Uniformity Central Run Degrader Live Dead No. Fluence <Flux> Error (%) (%) Shift (%) Dose Al Time Time 179 9.96E+05 2.53E+04 0.16 90.00 7.00 90.81 0 39.28 0 180 9.88E+05 2.25E+04 0.16 89.00 7.00 90.39 0 43.87 0 181 1.01E+06 2.38E+04 0.16 89.00 7.00 91.91 0 42.27 0 182 9.97E+05 2.27E+04 0.16 88.00 6.00 91.19 0 44 0 183 9.96E+05 2.25E+04 0.16 88.00 7.00 91.06 0 44.27 0 184 9.98E+05 2.35E+04 0.16 87.00 7.00 91.33 0 42.42 0 185 9.92E+05 2.45E+04 0.16 87.00 7.00 90.77 0 40.48 0 186 1.00E+06 2.59E+04 0.16 83.00 12.00 91.69 0 38.72 0 187 9.90E+05 2.38E+04 0.16 85.00 10.00 90.59 0 41.68 0 188 1.01E+06 2.40E+04 0.16 85.00 10.00 92.37 0 42.08 0 189 1.00E+06 3.04E+04 0.16 87.00 9.00 91.82 0 33.02 0 190 1.01E+06 2.61E+04 0.16 90.00 6.00 92.09 0 38.55 0


27

B2.0 Krypton

Run File Test Run Ion Ion Number Ext Date Time Beam MeV/u Energy LET Range

1 #6a 2/19/2007 17:09:17 Kr 24.8 1858 20.6 284.4 2 #6b 2/19/2007 17:10:34 Kr 24.8 1858 20.6 284.4 3 #6c 2/19/2007 17:11:51 Kr 24.8 1858 20.6 284.4 4 #6d 2/19/2007 17:13:00 Kr 24.8 1858 20.6 284.4 5 #6e 2/19/2007 17:14:22 Kr 24.8 1858 20.6 284.4 6 #6f 2/19/2007 17:15:42 Kr 24.8 1858 20.6 284.4 7 #6g 2/19/2007 17:17:15 Kr 24.8 1858 20.6 284.4 8 #6h 2/19/2007 17:18:45 Kr 24.8 1858 20.6 284.4 9 #6i 2/19/2007 17:20:04 Kr 24.8 1858 20.6 284.4

10 #6j 2/19/2007 17:21:21 Kr 24.8 1858 20.6 284.4 11 #6k 2/19/2007 17:22:31 Kr 24.8 1858 20.6 284.4 12 #6l 2/19/2007 17:23:42 Kr 24.8 1858 20.6 284.4 13 #6m 2/19/2007 17:2446 Kr 24.8 1858 20.6 284.4 14 #6n 2/19/2007 17:25:53 Kr 24.8 1858 20.6 284.4 15 #6o 2/19/2007 17:27:10 Kr 24.8 1858 20.6 284.4

Run Ion Ion Flux Uniformity Central Run Degrader Live DeadNo. Fluence <Flux> Error (%) (%) Shift (%) Dose Al Time Time 1 1.00E6 2.59E4 0.16 90.00 7.00 330.8 0 38.68 0 2 9.96E5 2.15E4 0.16 92 6 329 0 46.32 0 3 9.92E5 2.17E4 0.16 90 7 328 0 45.75 0 4 1.01E6 2.02E4 0.16 89 8 331.9 0 49.65 0 5 1.00E6 1.75E4 0.16 88 8 330.7 0 57.07 0 6 1.01E6 1.37E4 0.16 89 8 332.1 0 73.6 0 7 9.99E5 1.42E4 0.16 90 7 329.8 0 70.18 0 8 1.00E6 1.76E4 0.16 90 7 330.4 0 56.82 0 9 9.93E5 1.99E4 0.16 88 8 328 0 49.92 0

10 1.01E6 2.03E4 0.16 86 11 332.1 0 49.52 0 11 1.00E6 2.29E4 0.16 86 11 331.6 0 43.8 0 12 9.94E5 3.28E4 0.16 85 11 328.4 0 39.88 0 13 1.00E6 2.4E4 0.16 85 11 331.9 0 41.9 0 14 9.90E5 1.90E4 0.16 85 11 327.0 0 52.22 0 15 1.53E5 2.06E4 0.4 88 9 50.51 0 7.43 0


16 #6p 2/19/2007 18:08:20 Kr 24.8 1858 20.6 284.4 17 #6q 2/19/2007 18:14:40 Kr 24.8 1858 20.6 284.4 18 #6r 2/19/2007 18:23:32 Kr 24.8 1858 20.6 284.4 19 #6s 2/19/2007 18:25:34 Kr 24.8 1858 20.6 284.4 20 2/19/2007 Kr 24.8 1858 20.6 284.4


28

21 2/19/2007 Kr 24.8 1858 20.6 284.4 22 #6u 2/19/2007 18:34:31 Kr 24.8 1858 20.6 284.4 23 #6v 2/19/2007 18:36:32 Kr 24.8 1858 20.6 284.4

Run Flux Uniformity Central Run Degrader Live DeadNo. Fluence <Flux> Error (%) (%) Shift (%) Dose Al Time Time 16 1.00E6 1.31E4 0.16 94.00 4.00 331.3 0 76.43 0 17 1.00E6 1.36E4 0.16 95 4 331.5 0 73.95 0 18 1.00E6 1.35E4 0.16 95 3 330.4 0 73.98 0 19 1.38E6 1.24E4 0.13 95 4 457.0 0 111.53 0 20 21 22 1.00E6 1.21E4 0.16 94 4 332.0 0 83.05 0 23 9.98E5 1.22E4 0.16 96 3 329.6 0 81.52 0

Run File Test Run Ion Ion

Number Ext Date Time Beam MeV/u Energy LET Range 24 #6w 2/19/2007 18:43:010 Kr 24.8 1858 20.6 284.4 25 #6x 2/19/2007 18:45:15 Kr 24.8 1858 20.6 284.4 26 #6y 2/19/2007 18:47:42 Kr 24.8 1858 20.6 284.4 27 #6z 2/19/2007 18:49:33 Kr 24.8 1858 20.6 284.4 28 #70 2/19/2007 18:51:25 Kr 24.8 1858 20.6 284.4 29 #71 2/19/2007 18:53:16 Kr 24.8 1858 20.6 284.4 30 #72 2/19/2007 18:54:57 Kr 24.8 1858 20.6 284.4 31 #73 2/19/2007 18:56:37 Kr 24.8 1858 20.6 284.4 32 #74 2/19/2007 18:58:13 Kr 24.8 1858 20.6 284.4 33 #75 2/19/2007 18:59:55 Kr 24.8 1858 20.6 284.4 34 #76 2/19/2007 19:01:37 Kr 24.8 1858 20.6 284.4 35 #77 2/19/2007 19:03:24 Kr 24.8 1858 20.6 284.4 36 #78 2/19/2007 19:05:12 Kr 24.8 1858 20.6 284.4 37 #79 2/19/2007 19:10:12 Kr 24.8 1858 20.6 284.4 38 #7a 2/19/2007 19:11:50 Kr 24.8 1858 20.6 284.4 39 #7b 2/19/2007 19:13:25 Kr 24.8 1858 20.6 284.4 40 #7c 2/19/2007 19:15:03 Kr 24.8 1858 20.6 284.4 41 #7d 2/19/2007 19:17:12 Kr 24.8 1858 20.6 284.4

Run Ion Ion Flux Uniformity Central Run Degrader Live DeadNo. Fluence <Flux> Error (%) (%) Shift (%) Dose Al Time Time 24 1.00E6 1.34E4 0.16 97.00 3.00 330.2 0 74.72 0 25 9.95E5 1.23E4 0.16 97 2 328.7 0 81.05 0 26 9.98E5 1.24E4 0.16 96 3 329.8 0 80.72 0 27 1.01E6 1.20E4 0.16 96 3 331.9 0 83.63 0 28 1.00E6 1.24E4 0.16 95 4 332.3 0 80.97 0 29 1.00E6 1.36E4 0.16 96 3 330.8 0 73.67 0 30 1.00E6 1.40E4 0.16 95 4 331.2 0 71.38 0 31 1.00E6 1.52E4 0.16 95 4 330.3 0 65.58 0


29

32 9.99E5 1.41E4 0.16 95 4 329.8 0 70.78 0 33 9.94E5 1.39E4 0.16 95 4 328.2 0 71.67 0 34 1.00E6 1.30E4 0.16 95 4 330.3 0 76.72 0 35 1.01E6 1.28E4 0.16 94 4 332.2 0 78.4 0 36 1.31E5 1.18E4 0.44 93 5 43.27 0 11.08 0 37 9.95E5 1.39E4 0.16 95 4 328.6 0 71.27 0 38 9.99E5 1.41E4 0.16 94 4 330.1 0 71 0 39 1.00E6 1.38E4 0.16 95 4 330.8 0 72.68 0 40 1.01E6 1.42E4 0.16 95 4 331.9 0 70.9 0 41 1.00E6 1.37E4 0.16 94 5 331.1 0 73.12 0


Number Ext Date Time Beam MeV/u Energy LET Range 42 #7e 2/19/2007 19:22:08 Kr 24.8 1858 20.6 284.4 43 #7f 2/19/2007 19:23:46 Kr 24.8 1858 20.6 284.4 44 #7g 2/19/2007 19:25:26 Kr 24.8 1858 20.6 284.4 45 #7h 2/19/2007 19:27:15 Kr 24.8 1858 20.6 284.4 46 #7i 2/19/2007 19:30:24 Kr 24.8 1858 20.6 284.4 47 #7j 2/19/2007 19:32:03 Kr 24.8 1858 20.6 284.4 48 #7k 2/19/2007 19:33:42 Kr 24.8 1858 20.6 284.4 49 #7l 2/19/2007 19:35:13 Kr 24.8 1858 20.6 284.4

Run Ion Ion Flux Uniformity Central Run Degrader Live DeadNo. Fluence <Flux> Error (%) (%) Shift (%) Dose Al Time Time 42 1.00E6 1.35E4 0.16 94.00 4.00 331.9 0 74.37 0 43 1.01E6 1.40E4 0.16 95 4 332.0 0 71.68 0 44 9.95E5 1.39E4 0.16 95 4 328.6 0 71.48 0 45 1.00E6 1.46E4 0.16 96 1 331.3 0 68.87 0 46 1.00E6 1.55E4 0.16 96 3 330.3 0 64.48 0 47 9.96E5 1.47E4 0.16 95 4 328.8 0 67.72 0 48 1.01E6 1.54E4 0.16 96 3 332.6 0 65.42 0 49 1.01E6 1.48E4 0.16 96 3 332.3 0 68.05 0


Number Ext Date Time Beam MeV/u Energy LET Range 50 #7m 2/19/2007 19:45:12 Kr 24.8 1858 20.6 284.4 51 #7n 2/19/2007 19:46:48 Kr 24.8 1858 20.6 284.4 52 #7o 2/19/2007 19:48:21 Kr 24.8 1858 20.6 284.4 53 #7p 2/19/2007 19:49:57 Kr 24.8 1858 20.6 284.4 54 #7q 2/19/2007 19:53:01 Kr 24.8 1858 20.6 284.4 55 #7r 2/19/2007 19:54:24 Kr 24.8 1858 20.6 284.4 56 #7s 2/19/2007 19:55:40 Kr 24.8 1858 20.6 284.4 57 #7t 2/19/2007 20:03:02 Kr 24.8 1858 20.6 284.4 58 #7u 2/19/2007 20:04:29 Kr 24.8 1858 20.6 284.4 59 #7v 2/19/2007 20:05:56 Kr 24.8 1858 20.6 284.4 60 #7w 2/19/2007 20:07:18 Kr 24.8 1858 20.6 284.4


30

61 #7x 2/19/2007 20:08:39 Kr 24.8 1858 20.6 284.4 62 #7y 2/19/2007 20:10:22 Kr 24.8 1858 20.6 284.4 63 #7z 2/19/2007 20:11:47 Kr 24.8 1858 20.6 284.4 64 #80 2/19/2007 20:13:18 Kr 24.8 1858 20.6 284.4 65 #81 2/19/2007 20:14:53 Kr 24.8 1858 20.6 284.4 66 #82 2/19/2007 20:16:50 Kr 24.8 1858 20.6 284.4 67 #83 2/19/2007 20:20:33 Kr 24.8 1858 20.6 284.4 68 #84 2/19/2007 20:21:53 Kr 24.8 1858 20.6 284.4 69 #85 2/19/2007 20:23:12 Kr 24.8 1858 20.6 284.4 70 #86 2/19/2007 20:30:28 Kr 24.8 1858 20.6 284.4 71 #87 2/19/2007 20:31:43 Kr 24.8 1858 20.6 284.4 72 #88 2/19/2007 20:33:10 Kr 24.8 1858 20.6 284.4 73 #89 2/19/2007 20:03:02 Kr 24.8 1858 20.6 284.4

Run Ion Ion Flux Uniformity Central Run Degrader Live DeadNo. Fluence <Flux> Error (%) (%) Shift (%) Dose Al Time Time 50 1.00E6 1.52E4 0.16 97.00 2.00 331.4 0 65.97 0 51 1.00E6 1.51E4 0.16 97 2 331.6 0 66.35 0 52 1.00E5 1.48E4 0.16 97 2 331.4 0 67.82 0 53 1.01E6 1.46E4 0.16 97 2 332.3 0 68.7 0 54 9.93E5 2.11E4 0.16 98 1 328.1 0 47.13 0 55 1.01E6 2.01E4 0.16 95 3 332.7 0 50.02 0 56 9.95E5 1.87E4 0.16 96 3 328.6 0 53.35 0 57 1.01E6 1.81E4 0.16 94 4 484.1 0 55.53 0 58 1.01E6 1.80E4 0.16 93 5 484.6 0 56.05 0 59 1.00E6 1.84E4 0.16 94 5 480.7 0 54.65 0 60 9.93E5 1.82E4 0.16 93 5 477.3 0 54.45 0 61 1.01E6 1.85.5E4 0.16 93 5 484.8 0 54.38 0 62 9.98E5 1.86E4 0.16 93 5 479.5 0 53.63 0 63 1.01E6 1.95E4 0.16 91 7 482.7 0 51.57 0 64 9.91E5 1.99E4 0.16 92 6 476.2 0 49.68 0 65 9.97E5 1.98E4 0.16 92 6 478.9 0 50.23 0 66 1.46E6 1.81E4 0.13 91 6 701.0 0 80.77 0 67 1.01E6 1.96E4 0.16 92 6 484.2 0 51.52 0 68 1.00E6 1.97E4 0.16 92 6 480.4 0 50.87 0 69 1.01E6 1.91E4 0.16 93 5 483.7 0 48.37 0 70 1.00E6 2.05E4 0.16 91 6 331.4 0 48.93 0 71 1.00E6 2.01E4 0.16 90 7 330.2 0 49.78 0 72 9.93E5 2.03E4 0.16 93 5 327.8 0 48.83 0 73 9.89E5 2.07E4 0.16 90 7 326.7 0 47.73 0


31

B3.0 Xenon


149 #ad 2/20/2007 00:54:36 Xe 24.8 2758 40.7 237.7 150 #ae 2/20/2007 00:55:24 Xe 24.8 2758 40.7 237.7 151 #af 2/20/2007 01:00:48 Xe 24.8 2758 40.7 237.7 152 #ag 2/20/2007 01:02:28 Xe 24.8 2758 40.7 237.7 153 #ah 2/20/2007 01:03:19 Xe 24.8 2758 40.7 237.7 154 #ai 2/20/2007 01:04:13 Xe 24.8 2758 40.7 237.7 155 #aj 2/20/2007 01:05:04 Xe 24.8 2758 40.7 237.7 156 #ak 2/20/2007 01:05:55 Xe 24.8 2758 40.7 237.7 157 #al 2/20/2007 01:06:44 Xe 24.8 2758 40.7 237.7 172 #am 2/20/2007 01:48:53 Xe 24.8 2758 40.7 237.7 173 #an 2/20/2007 01:49:39 Xe 24.8 2758 40.7 237.7 174 #ao 2/20/2007 01:50:24 Xe 24.8 2758 40.7 237.7 175 #ap 2/20/2007 01:51:10 Xe 24.8 2758 40.7 237.7 176 #aq 2/20/2007 01:51:55 Xe 24.8 2758 40.7 237.7 177 #ar 2/20/2007 01:52:42 Xe 24.8 2758 40.7 237.7 178 #as 2/20/2007 01:53:34 Xe 24.8 2758 40.7 237.7

Run Ion Ion Flux Uniformity Central Run Degrader Live DeadNo. Fluence <Flux> Error (%) (%) Shift (%) Dose Al Time Time 149 9.86E5 4.08E4 0.16 90.00 6.00 642.6 0 24.13 0 150 9.88E5 4.11E4 0.16 89 7 643.8 0 24.02 0 151 9.86E5 2.84E4 0.16 92 6 643 0 34.75 0 152 9.96E5 3.97E4 0.16 96 2 649.2 0 25.07 0 153 1.01E6 3.87E4 0.16 95 3 656 0 26.02 0 154 1.01E6 3.98E4 0.16 96 2 658.8 0 25.42 0 155 9.91E5 3.69E4 0.16 94 4 646 0 26.88 0 156 9.92E5 4.05E4 0.16 95 2 646.8 0 24.52 0 157 9.81E5 4.27E4 0.16 95 2 639.8 0 22.98 0 172 1.01E6 4.62E4 0.16 97 2 655.7 0 21.77 0 173 9.83E6 4.61E4 0.16 97 1 640.9 0 21.33 0 174 9.91E5 4.27E4 0.16 96 3 646.2 0 23.22 0 175 9.87E5 4.34E4 0.16 97 2 643.8 0 22.73 0 176 9.86E5 4.06E4 0.16 94 4 642.9 0 24.28 0 177 1.01E6 3.73E4 0.16 92 5 658.1 0 27.03 0 178 9.91E5 3.02E4 0.16 91 7 646.3 0 32.87 0


32

Appendix C: Experimenters Shot and Bias Log Sheets C1.0 Krypton


33


34


35


36


37

C2.0 Xenon


38

C3.0 Argon


39

Appendix D – Recorded/Monitored Drain and Gate Current << SEE EXCEL SPREADSHEET FOR DATA ND PLOTS OF RECORDED DRAIN AND GATE CURRENTS >>

<< NASA_CURRENT_LOG1.XLS >>

Excel spreadsheet (NASA_CURRENT_LOG1.xls) contains all the plotted drain and gate currents logged for each device and each run. The NASA_CURRENT_LOG1.xls contains all the plotted drain and gate current waveforms. This spreadsheet was sent as a separate file due to the size of the report and spreadsheet!


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Appendix E: Notes and Setup Information

TEST SETUP CONNECTIONS Two Keithley 237s were connected to the switch box. Output HI on the back panel of the two Keithleys is connected to the Switch Box using Triax Cable. One is designated the drain (Address 18) and the other is designated Gate (Address 17). The switch box is a custom-built box employing an eighteen-position, 3-pole switch, which is used to select any one of the eighteen different positions. Each position connects a different socket. One of the four poles is connected to the drain; one is connected to the gate; and one is connected to source (Ground). The fourth pole is floating. Two 40-Pin ribbon cables are connected to the back panel of the switch box. One is labeled Connector A and the other Connector B. The other end of each 40-PIN ribbon cable is connected to its matching connector on the DUT board (Connectors are Labeled Connector A and Connector B). Verify proper cable orientation (red stripe is connected to PIN one of Switch Box and DUT Board). Ribbon cables are 22 ft in length (a 10ft and 12 ft connected together to form one cable). With all connections finalized, verify test board configuration by applying –5 volts to the Gate and 10 volts to the Drain. Each socket position was selected by turning the 18-position switch to its appropriate position and then the voltages were verified at the DUT Board using a multimeter. This technique provides a quick check that all the connections are correct and working. Equipment List:

COMPAQ 486 Controller HP Basic Program environment for controlling instruments SEU_10 Custom Program to control, monitor, and record currents Keithley 237 Drain Power Supply Keithley 237 Gate Power Supply Custom SEE Test Board (DUT Interface Board)


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Appendix F: Acronyms ASTM American Society of Test Methods DUT Device Under Test ESD Electrostatic Discharge LET Linear Energy Transfer (usually given in units of MeV/mg/cm2) NAVSEA Naval Sea Command NIST National Institute of Standards and Tests NSWC Naval Surface Warfare Center PCB Printed Circuit Board PIN P-Type, Intrinsic, N-Type Diode P/N Part Number S/N Serial Number TLD Thermoluminescent Dosimeter Flux Particles per unit area per second Fluence Total particles per unit area Cyclotron Run Reference to a specific exposure SEE Single Event Effects SEB Single Event Burnout SEGR Single Event Gate Rupture SEU Single Event Upset VDS Drain-to-source voltage VGS Gate-to-source voltage

(revision no. 1) final report microsemi power mosfet ... · issue date: 26 mar 2007...

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