![Page 1: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/1.jpg)
1
MicroMachined Silicon Detectors
Marc Christophersena and Bernard PhlipsU.S. Naval Research Laboratory
Code 7651, Gamma Ray Imaging Laboratory (a) NRC postdoctoral fellow
Contact: [email protected] 2027673572
![Page 2: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/2.jpg)
2
MEMS: MicroElectromechanical Systems
MEMS
Micrograph, ante with MEMS structures, developed ~ 1015 years ago.
Evolution of MEMS
last 10 years
MEMS based gyroscopeimages from Fraunhofer Institute and Apple
![Page 3: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/3.jpg)
3
MEMS: MicroElectromechanical Systems
MEMS
images from Sandia
![Page 4: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/4.jpg)
4
aspect ratio up to 600
High Aspect Ratio Structures
one enabling feature:high aspect ratio structures
![Page 5: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/5.jpg)
5
• Trenched GammaRay Detector• Curved Radiation Detector
Outline
![Page 6: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/6.jpg)
6
3D Detectors
![Page 7: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/7.jpg)
7
h+
e
+
W3D E
Bulk
h+
e
+
E
p+
n
n+
W2D
+
short distance between electrodes:• low full depletion voltage• short collection distance
more radiation tolerant than planar detectors!
S.I. Parker, C. J. Kenney, J. Segal, Nucl. Instr. Meth. Phys. Res. A 395 (1997) 328
Standard 3D Detectors
DRAWBACK: Fabrication process of 3D devices is not standard.
![Page 8: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/8.jpg)
8
h+
W3DBulk
h+
e
+
E
p+
n
n+
W2D
+
e
EW2D
Trenched GammaRay Detector Concept
• mm thick detectors• decoupling thickness and depletion voltage
![Page 9: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/9.jpg)
9
Trenched GammaRay Detector
n+
C. Piemonte, et al., Nucl. Instr. Meth. Phys. Res. A 541 (2005)
Z. Li, et al., Nucl. Instr. Meth. Phys. Res. A 139 (2007)
Trenched GammaRay Detector Concept
Coaxial Ge Detector
~ 0.3 – 0.5 mm 25 mm ~ 30 mm
![Page 10: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/10.jpg)
10
Finite Element Simulations – Ideal Structure
Our goal:
5 mm thick trenched detector with near trenches for lateral depletion and charge collection.
Silvaco® simulation result
![Page 11: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/11.jpg)
11
Trenched GammaRay Detector Challenges
Fabrication Challenges:• microfabrication – highaspect
ratio trench/hole arrays, millimeters deep
• junction formation – homogeneous junction (no ionimplantation, I2)
• leakage currents – maintain high minority carrier lifetime
Silvaco® simulation result
![Page 12: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/12.jpg)
12
Microfabrication
• 5000 ft2 laboratory space• temperature controlled• EM shielding• vibration isolation• acoustic isolation
• SEM (scanning electron microscope)• pattern generator• mask aligner• reactive ion etcher (RIE) & DRIE• ebeam evaporator
![Page 13: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/13.jpg)
13
Simplified Process Sequence*
2 mm thick 4” Si oxidation
* Does not include cleaning steps.
Phosphorous I2
PECVD oxidesopening of SiO2 hardmaskcryogenic DRIE
opening of SiO2 hardmask solid source Boron diffusion SiO2 etch + metallization
![Page 14: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/14.jpg)
14
Simplified Process Sequence*
2 mm thick 4” Si oxidation Phosphorous I2
PECVD oxidesopening of SiO2 hardmaskcryogenic DRIE
opening of SiO2 hardmask solid source Boron diffusion SiO2 etch + metallization
* Does not include cleaning steps.
![Page 15: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/15.jpg)
15
Silicon DRIE (Deep Reactive Ion Etching)
“types” of deep anisotropic plasma etching:• Bosch process,• room T continuous process,• cryogenic process.
A. Ayon et al., Sens. Act. A, 91, 2001
maximal reported depth 300 – 600 µm (wafer through and via etching)
SEM crosssection micrograph
50 µm
![Page 16: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/16.jpg)
16
SF6 + O2 ICP plasma
SiF4
O+F+ions
ultra thin layer of SiO2
110 °C
limitation of spontaneous chemical reaction and improvement of O sticking
Si
• no polymer contamination (reactor, substrate) in comparison to Bosch,• low sidewall roughness,• DC bias < 10 V (no silicon damage)• high etch selectivity ~ 500 – 1,000 to SiO2,
• BUT sensible process and not so flexible than Bosch process!
Cryogenic DRIE
mask, SiO2
![Page 17: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/17.jpg)
17
Cryogenic DRIE
SEM micrograph, bird’seyeview.
Final devices will have narrower trench arrays.
• aspect ratio ~ 12
• 1.75 mm deep
![Page 18: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/18.jpg)
18
SEM crosssection micrographstain etched Boron junction
requirements:• penetrate trench array (no I2),• gaseous, spinon, or solid
source doping,• no strong gettering effect
(like Phosphorous).
Boron Diffusion
2 µm
![Page 19: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/19.jpg)
19
Leakage Current
• IV curve of trenched 3D gammaray detector (0.5 mm thick silicon substrate)
• low leakage current• strip dimensions: 0.85 x 7.1 mm
optical micrograph, topview
150 µm
![Page 20: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/20.jpg)
20
500 µm
Am241 Spectrum
• Am241 source• energy resolution is ~ 2.3
keV FWHM at 59.5 keV• excellent charge collection
![Page 21: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/21.jpg)
21
2 mm Thick Wafer
• high leakage current due to backside damage,• full depletion at 50 V.
substrate ~ 20,000 Ωcm
![Page 22: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/22.jpg)
22
2 mm Thick Wafer
Am241 & Co57 sources
energy resolution: 3.0 keVFWHM at 60 keV
Am214
Co57
![Page 23: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/23.jpg)
23
The quest for millimeter deep trenches in silicon …
• anisotropy (vertical sidewall),• mask material (SiO2…),• roughness and slope sidewall,• charge collection inside trenches,• junction formation,• selectivity SiO2:mask (O/F, pressure, DC bias),• etch rate (12 µm/min),• increase the aspect ratio.
under control
challenges
Discussion Trenched GammaRay Detector
![Page 24: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/24.jpg)
24
• Trenched GammaRay Detector• Curved Radiation Detector
Outline
![Page 25: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/25.jpg)
25
88mm
37.5mm24.4mm Current Proposed
• need to shape surfaces• need high precision• preserve silicon quality• no “machining”• clean room processes only
Particle Physics Vertex Detectors
![Page 26: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/26.jpg)
26
• The layer of resist is exposed in specific areas through a mask.
• Development washes away exposed resist.
• A plasma etch step transfers the resist pattern into silicon.
• In the final step, resist is removed.
substratephotoresist
UV Lightmask
Exposure
Developing
Plasma Etching
Finished Product
Pattern Transfer
Standard Lithography
![Page 27: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/27.jpg)
27
• Photosculpting the photoresist (or other photosensitive materials) by spatially variable exposure.• The thickness of the photoresist after development depends on the local dose of UV irradiation• Local dose is adjusted to take into account the nonlinear photoresponse of the particular photoresist and proximity effects.• The 3D resist profiles can be transferred into different etch depths or used for molding. The combination of reactive ion etching and graytone lithography is called graytone technology.
Pattern Transfer Etching
GrayTone Lithography
![Page 28: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/28.jpg)
28
UV light
Diffuser
PhotoMask
PhotoResist
Siliconsubstrate
Exposed region
• Our approach presents true graytone lithography by using simple contact lithography with an optical diffuser. These contact lithography aligners are widespread in microelectronics laboratories and industry. • The main idea is to randomize the collimated light using an optical diffuser to generate uniform, controllable intensity distributions in the photoresist.
Our Approach
Traditional Gray-tone Lithography• Stepper exposure: Binary pattern arrays with submicrometer resolution on
standard chromeonglass masks (expensive masks), patented by Gal 1994.• High Energy Beam Sensitive (HEBS) Glass: Different Ag+ ion
concentrations generated by exposing the HEBSglass , patented and commercialize by Canyon Materials, Inc.,1994.
GrayTone Lithography
![Page 29: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/29.jpg)
29
3D molded replica 3D sinusoidal resist profile
We successfully have shown complex 3D resist profiles. PDMS (polydimethylsiloxane) replica structures have been obtained.
GrayTone Lithography
![Page 30: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/30.jpg)
30
GrayTone Lithography
Optical micrograph, top view Profilometer scan
![Page 31: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/31.jpg)
31
Deep Reactive Ion Etching
SF6 plasma
C4F8 plasma
SF6 plasma
SiF4F+ions
thin fluorocarbon polymer film (passivation)
Si
Si
Simask
ions
etch selectivity (etch rate silicon vs. photoresist): 70sufficient etch rate of photoresist needed for pattern transfer
![Page 32: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/32.jpg)
32
Pattern Transfer - Etching
GrayTone Lithography
graytone resist
![Page 33: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/33.jpg)
33
cross section, SEM micrograph
Trench Etching
![Page 34: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/34.jpg)
34
Trenched GammaRay Detector Concept
100 80 70 60 50 40
100 90
90
80 70 60 50 40 50
z
y
h+
e
+
E
+
S.I. Parker, C. J. Kenney, J. Segal, Nucl. Instr. Meth. Phys. Res. A 395 (1997) 328
E. Gatti, P. F. Rehak, Nucl. Instr. Meth. Phys Res. A225 (1984) 608
e
![Page 35: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/35.jpg)
35
Finite Element Simulation
thermal electron leakage currentpotential distribution
![Page 36: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/36.jpg)
36
Finite Element Simulation
potentials along red lines
![Page 37: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/37.jpg)
37
GrayTone Lithography – Curved Detector
![Page 38: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/38.jpg)
38
Curved Detector
SEM micrographmechanical sample
photograph
![Page 39: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/39.jpg)
39
Curved Detector
• Equipotential and field lines for a partly curved (a) and curved detector (b).
• For the partially curved detector the collection time depends on the position due to thickness variations.
singlesided etched
doublesided etched
![Page 40: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/40.jpg)
40
Curved Detector – Strip Detector
Optical micrograph, top view, strip dimensions 14 x 0.8 mm
• some surface roughness due to Bosch DRIEetching• modified lithography on curved surface
![Page 41: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/41.jpg)
41
substrate ~ 20,000 Ωcm
Curved Radiation Detector – IV, CV Curve
• singlesided strip detector• halfpipe detector, under reverse bias
![Page 42: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/42.jpg)
42
Curved Radiation Detector
2.9 keV at 59.54 keV
• singlesided strip detector• halfpipe detector, fully depleted
![Page 43: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/43.jpg)
43
5.38 keV at 59.54 keV
Curved Radiation Detector
• singlesided strip detector• doublesided etched detector, fully depleted
![Page 44: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/44.jpg)
44
Curved Detector – Pixel Detector
Optical micrograph, top view, pixel dimensions 150 x 150 µm
![Page 45: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/45.jpg)
45
Curved Radiation Detector
1.73 keV at 59.54 keV
• pixel detector• halfpipe detector, fully depleted
![Page 46: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/46.jpg)
46
• regular setup– 3element lens– planar focal plane array
• curved focal plane array– 1element lens– curved focal plane array
Outlook – Wide Field of View Camera
![Page 47: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/47.jpg)
47
ntype silicon
ptype silicon
Silicon dioxide insulating layerPolysilicon electrodes
Inco
min
g ph
oton
s
Backside electrode for depletion, ITO (Indium Tin Oxide)
300 µm
• The use of a highresistivity substrate permits fully depleted operation at reasonable bias voltages.• This electric field extends essentially all the way to the backside contact, hence the term full depletion.
depleted+100 V
No Effect on CCD Fab line. Final curvature already present.
Outlook – Wide Field of View Camera
![Page 48: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/48.jpg)
48
Conclusions
The basic structure of a thick gammaray detector based on trenched substrates has been shown. These detectors have low leakage currents and have an energy resolution of ~ 2.3 keV FWHM at 59.5 keV.
2 mm thick silicon fully depleted at ~ 50 V.
Curved radiation detector due to “graytone technology”.
Pixel and strip detector on single and doublesided etch detectors.
Wide field of view camera based on curved backsided illuminated CCD.
![Page 49: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/49.jpg)
49
200 mm Wafer Processing
![Page 50: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/50.jpg)
50
200 mm Wafer Processing
• ~ 9k Ohmcm FZ material• 725 µm thickness• single side strip detector, 128 strips, 0.97 mm wide
and 125 mm long
![Page 51: MicroMachined Silicon Detectors - commons.lbl.gov · 3 MEMS: MicroElectromechanical Systems MEMS images from Sandia. 4 aspect ratio up to 600 High Aspect Ratio Structures one enabling](https://reader034.vdocuments.us/reader034/viewer/2022050718/5e1757a077306331a6529825/html5/thumbnails/51.jpg)
51
200 mm Wafer Processing
• Am241 source• energy resolution is ~ 2.6
keV FWHM at 59.5 keV (0.7 x 7 mm strip)