advanced methodology of nano device analysis - sematech

PAGE Sematech 2012

Advanced Methodology of Advanced Methodology of NanoNano Device AnalysisDevice Analysis-- Characterization and identification of Characterization and identification of nanonano defects in ICs, TSV, LED, and defects in ICs, TSV, LED, and

CMP slurry CMP slurry

Yong-Fen Hsieh, CEO of MA-tek

Contributors include JS Bow, CA Lu, YF Ko, and Kari n Ho.

Nanodefects session

PAGE Proprietary, DO NOT COPY WITHOUT PERMISSION. Any page, or pages of this report can not be used separately.

Agenda

Major applications will cover the topics as follows .• Untra-thin dielectrics:

– Thickness and Composition Characterization of High-K and ONO

• De-convolution of overlapped peaks of Si/Ta/Hf– TEM/EDX Line Profile

• As doping in S/D region– Short acquisition time with overlapped peaks de-convolution by Q-

map processing

• Si-Ge quantitative analysis– PMOS/NMOS identification by P-V EDX mapping– Ge% determination (EDX vs. SIMS)– Defects characterization

• Characterization of Recessed Gate – non-uniform gate oxide growth

• Device Burn-out at Spacer Edge – LDD junction breakdown

• Fault Isolation of a TSV Array by InGaAs Analysis• Blue LED, AlGaN/InGaN Quantum Well, Characterization

– Comparison of SIMS Depth Profile vs. TEM/EDX Line Scan

• Study of CMP slurry by Frozen Method and Nano Pipet

Metal-1 (Cu)

Metal-4 (Cul)

gate

Metal-2 (Cu)

Contact (W-plug)

Metal-3 (Cu)

This talk will focus mainly on P-V and X-S TEM 3D E DX, where EELS, SIMS, RBS, SEM, FIB will be employed for comparison.


Recent Progress of Analytical Tools DevelopmentRecent Progress of Analytical Tools Development

• TEM/EDX 3D detectors : FEI Osiris

• Various Softwares for data processing : Bruker, Q-map, TIA, self-developed

TEM/EDX

Easy operation

Insensitive to light elementssuch as C, N, O, and F.

SIMSTEM/EELS

Crater of 100 um scale range,Special designed pattern is required.

Complicated operation &thin TEM sample is required.

Poor detection limit

This combination is realized now.This combination is realized now.

> 0.1%

<1ppm

Z >8

Z <29


TEM/EDX Line Scan : Metal and Low -K oxide

M1

M2

M3


SRAM NMOS

0

500

1000

1500

2000

0 80 160 240 320 400 480

Distance, nm

ED

X c

ount

s, C

,N,O

,Ta

0

2000

4000

6000

8000

10000

12000

ED

X c

ount

s , C

u, S

i

O

N

C

Ta

Cu

Si

Continue – TEM/EDX Line-scanning : Metal and Low -K

Via

2 et

chin

g st

op la

yer.

Via

1 et

chin

g st

op la

yer.

M1

tren

ch e

tchi

ng s

top

laye

r.

M2 IMD-1M3M1

TRENCHIMD-2 ILD


IL (gate oxide)

High-k

metal gate

Si substrate

HREM : NMOS Gate


TEM/EDX Line Scan : NMOS Gate


0

10

20

30

40

50

60

70

80

0 6 12 18 24 30 36 42 48 54 60 66

Distance , nm

ED

X c

ount

s

O

Si

Ti

N

Ta

Al

Hf

Continue – TEM/EDX Line Scan : NMOS Gate

IL (

Gat

e O

xide

)H

fbas

ed H

igh-

kT

iN

Ta-

Si

Ti-A

l-O

TiNTi-Al Ti-r

ich

Ti-A

l

Ti-Al-OSi

substrateSi-oxide


Page 9

TEM BF(43 kx)

ONO Elemental Mapping by TEM / ONO Elemental Mapping by TEM / EELS EELS

-- Flash Memory CellsFlash Memory Cells

The thickness of poly-Si-2 is measured to be 42nm.

The thickness of poly-Si-1 is measured to be 39.1nm

ONO thicknesses are measured to be 5.8/2.9/4.6 nm

by HREM respectively.


Page 10

ONO Elemental Mapping by TEM / EELS

- Flash Memory Cells

Zero Loss Image Nitrogen map

Silicon map Oxygen map

EELS was chosen for ONO elemental mapping, owing to:

(1) Conventional EDX analysis has to tilt certain angle, because the lamella is not “edge-on” toward EDX detector.

(2) The X-ray radiation efficiency of light elements, such as C, N and O, are that good as that of heavy elements.


Zero Loss Image

Si

N O

EELS Mapping – Nitrogen, Oxygen

By Tencai G2 F20

Mapping time ~ 1 min per element, but TEM/EELS system alignment and operation parameters settingtake long time of operation (2-3hrs). Sample drifting shall be an issue of EELS analysis.

In addition, thin sample, < 50nm, is required, which is critical to EELS signal enhancement.


HAADF

Si

N O

Mapping time = 30mins

By FEI Osiris,equipped with 3D EDX, 4 detectors

3D EDX Mapping – Nitrogen, Oxygen

This is the same sample for EELS mapping, ~50nm thick.

If a thicker specimen (~100nm) is used, the intensity will be even higher.


0

20

40

60

80

100

120

0 0.002 0.004 0.006 0.008 0.01 0.012 0.014 0.016

Si ON

EDX Line profile extracted from 3D EDX mapping data

5.1nm

6.8nm5.1nm

O

Typically, people use FWHM to derive layer thickness, but there is certain deviation from HREM measurement.

Cou

nts,

arb

itrar

y un

it


0

20

40

60

80

100

12 14 16 18 20 22 24 26 28 30 32

Distance (nm)

at%

N O Si

Consistent N & O depth profiling by 3D EDX & EELS in S iOxNy Layer

0.00E+00

1.00E+05

2.00E+05

3.00E+05

4.00E+05

5.00E+05

0 2 4 6 8 10 12 14 16 18 20

Distance (nm)

Inte

nsity

N ON

Pt SiO2 SiOxNySi

SiO2

EDX

EELS

0

20

40

60

80

100

0 5 10 15 20 25 30 35

Distance (nm)

at%

N O Si

N O

OSi

3D EDX EELS

O

O


0.0

20.0

40.0

60.0

80.0

100.0

0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0Position (nm)

at%

N O SiN O Si

SiOxNy SiOxSiOxPt Si

�� The deviation of N and O in three line profiles is within 5%.�� The large deviation in Pt layers was resulted from its complicated atomic structure.

Repeatability of 3D EDX Line Profiles


Ta M+Si

Ta L

O

Si-sub

TEM/EDX Line Scan of Si/Ta/Cu –De-convolution of overlapped peaks

0

50

100

150

200

250

300

350

400

0 5 10 15 20 25 30 35 40

Ta La

Ta Ma

Si Ka

0

50

100

150

200

250

300

350

400

0 5 10 15 20 25 30 35 40

TaLa

Ta + Si

Ta M

Si

Ta L

Ta L

Ta M+Si

Si K Cu Ka

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0X-ray Energy (KeV)

Cou

nts

Si K = 1.740 KeV Cu L = 0.93 KeV Ta La = 8.145 KeV

Ta LaTa MDE1 (SiK-TaM) = 0.031 KeV DE2 (CuLa-TaLa) = 0.105 KeV

Ta Lb1 = 9.342 KeVTa Lb2 = 9.650 KeV

Ta Ma = 1.709 KeV

Cu Ka = 8.04 KeV

Cu Kb = 8.904 KeV

Let I 1 = intensity @ 1.74 KeV

I1 = Si, K + Ta, Mα α α α = Si, K + X * Ta, Lαααα1

(Assume Ta, Mαααα= X * Ta, Lαααα1)

Then, Si, K = I 1 – X* Ta, Lαααα1


Si, K / Hf, Mα / Ta, MαSi, K @ 1.739 KeVHf, Mαααα @ 1.644 KeV

Ta, Mα α α α @ 1.709 KeV

∆∆∆∆E = 0.094 KeV

∆∆∆∆E = 0.030 KeV

Limit of resolution, δδδδE = 0.135 KeV / Mn, K @ 5.894 KeV

SiGeHfOx

SiTaN

Assuming in Ta/Hf/Si system,I1 = Si, K + X* Ta, Lb1 + Y* Hf, Lb1

However, X* Ta, Lb1 is not independent of Hf signals.


SiGeHfOx

SiTaN

Hf, Lαααα1 / Hf, Lαααα2 / Hf, Ln @ 8.000 KeV

Ta, Lαααα1 / Ta, Lαααα2 @ 8.000 KeV

Hf, Lα α α α / Ta, Lαααα@ 8.000 KeV

Hf, Lβ1β1β1β1 Ta, Lβ1 / β1 / β1 / β1 / Hf, Lβ2β2β2β2@ 9.34 KeVHf, Lβ2 β2 β2 β2 @ 9.34 KeV

Ta, Lβ1 β1 β1 β1 @ 9.34 KeV

Hf, Lβ1 β1 β1 β1 @ 9.01 KeV

Assuming in Ta/Hf/Si system,I1 = Si, K + X* Ta, Lb1 + Y* Hf, Lb1

However, X* Ta, Lb1 is not independent of Hf signals.


0

1000

2000

3000

4000

5000

6000

0 5 10 15 20 25 30 35 40 45 50

Position (nm)

Inte

nsity

Hf-Lb Ta-Lb Ti-K Si-K Ge-L O-K

Original Original EDX line profiles. Low intensity line profiles of Ta, Lβ1

and Hf, Lβ1 lie below Si line profile (red line).

SiGe

HfOx HfOx

TaN TaN

TiN TiN


0

1000

2000

3000

4000

5000

6000

0 5 10 15 20 25 30 35 40 45 50

Position (nm)

Inte

nsity

Hf M Ta M Ti K Si K Ge L O K

Si >> Ta/Hf.

(YHf = 3.6; XTa = 5.35)

This is an ideal result, which needs semi-empirical adjustment by engineering efforts.It is easy to separate Si from Hf (or Ta) in single stacked layer.It becomes much more complicated, when both Hf and Ta are involved.

ProcessedProcessed EDX line profiles. High intensity and separate line profiles of Ta Lβ1

(blue line) and Hf Lβ1 (purple line), but Si, K line profile became to be too low.

SiGe

HfOx HfOx

TaN TaN

TiN TiN

Si-rich Si-rich


STEM Image W As N

Ni O Si Ti

TEM/EDX Mapping TEM/EDX Mapping –– As doping in S/D regionAs doping in S/D region

Acquisition 10 mins without Q-Map data processing- Artifacts was resulted from peaks overlap (As, W, and Si).

Prior Art of EDX Mapping, under typical operation conditions, it takes ~ 30 mins for a set of EDX maps. However, As doping profile in S/D region will be only available when acquisition time is more than 4 hrs . Data below were acquired by FEI Osiris, equipped with 3D EDX detectors.


STEM Image W As N

Ni O Si Ti

Acquisition 10 mins and Q-Map data processing (2 hrs )- FREE of artifacts

Prior Art of EDX Mapping, under typical operation conditions, it takes ~ 30 mins for a set of EDX maps. However, As doping profile in S/D region will be only available when acquisition time is more than 4 hrs . Data below were acquired by FEI Osiris, equipped with 3D EDX detectors.

TEM/EDX Mapping TEM/EDX Mapping –– As doping in S/D regionAs doping in S/D region


TEM BF

HAADF (ZC)

Identification of PMOS device layout - Comparison of TEM and HAADF(ZC)

The unit cell was marked by red rectangles.HAADF imaging of NMOS/PMOS interface can define the cell size better than TEM imaging.

NMOS / PMOS / NMOS


Page 24

NMOS/PMOSinterface

The interface of NMOS poly and PMOS poly indicated that the processes of the NMOS poly and PMOS poly needed two masks.

Plain View (PV) TEM 43kx

NMOS active area

PMOS active area

NMOS poly

PMOS poly

contact


Mapping : NMOS/PMOS Differentiation

The NMOS active area was marked by purple rectangles, and discontinuous PMOS active

area was marked by blue rectangles. The elemental maps of Al, Ta and Ge were

shown clearly in NMOS and PMOS. Obviously, PV-TEM sample thickness is estimated to be

> 200nm in this study.

This work can be applied to benchmark analysis and IP infringement case.

GeTa (HK metal P-gate)

Al

NMOS

PMOS


Page 26

Ge (Si-Ge) N

HfNi (metal silicides)Ta (HK metal P-gate)W (contact)

C Si Al (HK metal P/N-gate) Ti (HK metal P/N-gate)

TEM/EDX Elemental Mapping

Raw Data

PMOS

PMOS

PMOS


SIMS Depth Profiling of 40% graded Ge and 26% Ge Characterized by a calibration standards prepared b y EAG.

0

5

10

15

20

25

30

35

40

45

50

0 20 40 60 80 100 120 140

Depth:[nm]

Con

cent

ratio

n:[A

tom

ic%

]

Ge(#1)

Ge(#5)Ge(#1)Ge(#1)Ge(#1)Ge(#1)

Ge(#5)Ge(#5)Ge(#5)Ge(#5)

40% graded Ge

26% Ge

� Quantitative analysis by TEM/EELS is much more comp licated than that by TEM/EDX.

- The specimen thickness has to be thinner than 50 nm to ensure single scattering condition, which is a must for EELS quantitative analysis. This will be challenging in TEM sample preparation.

- The acquisition time for Si and Ge will be quite different, because of the large energy loss difference of the corresponding characteristic edges (Si L2,3 @ 99 eV; Ge L2,3 @ 1217 eV). This will result in extra errors in quantitative analysis.

Si-Ge

Si


� There are 6 data points for TEM/EDX at each positio n, 3 from t = 80 nm (hollow marks), and 3 from t = 120 nm (solid marks). Thickness effect is not obvious.

� The concentration of Ge of both 26% and ~40% are ve ry well consistent with those analyzed by SIMS, 1-2% off-set only, where Si, Ge, and oxygen concentrations are obtained from EDX signal intensi ty.

t = 80/120 nm

0

20

40

60

0 1 2 3 4

Position

(at%

)

SIMS TEM/EDX

26% Ge

~ 40% Ge

Comparison of TEM/EDX and SIMS

(Oxygen included)


� There are 6 data points for TEM/EDX at each positio n, 3 from t = 80 nm (hollow marks), and 3 from t = 120 nm (solid marks). Thickness effect of TEM sample is not obvious.

� The concentration of Ge obtained from TEM/EDX are 3 - 6% off-set from those of SIMS, if Si-Ge are recalculated with oxygen excluded .

t = 80/120 nm

0

20

40

60

0 1 2 3 4Position

Ge/

Si r

atio

n

26% Ge

~ 40% Ge

SIMS TEM/EDX

Comparison of TEM/EDX and SIMS

(Oxygen excluded)


0.0

20.0

40.0

60.0

80.0

100.0

20.0 60.0 100.0 140.0Distance (nm)

at%

%Si %Ge %O

Quantitative Analysis of Si-Ge by TEM/EDX (2)

~ 30

�� The line profile was performed on a QMap processed i mage.

�� The Ge concentration is measured to be ~ 30% throug h the film.

�� The deviation is about 4% compared with RBS data.


Plan-view and Cross-section TEM reveals lateral, fa cet growth in different directions.

interface defects

SiGe

SiO2

SiSi-Ge Overgrowth on STI oxide is dependent on crysta l orientation . The degree of overgrowth and defect density can be studied in terms of Pattern/Size Effects and Material Growth conditions.


TEM Top view (PlanTEM Top view (Plan --view)view)

Discontinuous Si-Ge islands

FIB Top view (PlanFIB Top view (Plan --view)view)

Discontinuous Si-Ge islands


1um

0.79um

512Mb DDR SDRAM512Mb DDR SDRAM–– Recessed Gate (nonRecessed Gate (non --uniform gate oxide growth)uniform gate oxide growth)

P-2, local inter-connect, BL

P-1, gate, WL

BLC NCNC

RGRG RGRG


DRAM cell arrayDRAM cell array --

Characterization of Characterization of gate oxide thinning gate oxide thinning

by planby plan --view TEMview TEM

Cross-section

A A’

Bit line contact

Channel

Gate Oxide Thinning at Trench Corner

Bare Si sub.

Poly-Si gate on Si sub.

X-S

P-V

BLC NCNC

BLC NCNC

BLC

NC

WL

WL

Recessed GateRecessed Gate

RGRG RGRG


Page 35

TEM imageTEM image

Failure site

S/D implantation

Channel region

Channel region

Silicide S/DSEM imageSEM image

Device BurnDevice Burn --out at Spacer Edge out at Spacer Edge –– LDD junction breakdownLDD junction breakdown(The burn(The burn --out mark is visible in TEM, but invisible in SEM )out mark is visible in TEM, but invisible in SEM )


channelchannel

channelchannel

S/D with S/D with silicidationsilicidation

S/D without S/D without silicidationsilicidation

spacerspacer

spacerspacer

Local burnLocal burn--out at out at

spacer edgespacer edge

Precision Plan-view SEM, high angle-tilt

Page 36

Local burnLocal burn --out at out at spacer edgespacer edge

Precision Plan-view TEM

ESD fail at spacer edge


FIB X-S

TSV

Laser mark

Si

Fault Isolation of Fault Isolation of a TSV Array a TSV Array

by by InGaAsInGaAs AAnalysisnalysis X-S SEM

emission spot

P-V OM in InGaAs

OXIDE

TSV (Au)

Si

Gold metal fill in oxide crack and penetrate to silicon substrate

Step1

Step2

Step3

Step4

Deep trench > 30 um

X-S OM in InGaAs


LED AlGaN/InGaN Quantum Well Characterization -Comparison of SIMS Depth Profile vs. TEM/EDX Line Scan

Difficulties of SIMS analysis:1. Deep crater > 8um2. Surface roughness resulted from faceted

epitaxial layer


LED Quantum Well Characterization -Comparison of SIMS Depth Profile vs. TEM/EDX Line Scan

SIMS

Owing to crater effect, SIMS Peak broadening can be improved in TEM/EDX analysis.

TEM/EDX


Depth Profiling of Al and In in Thick layer vs. Thin layer

SIMS: Al peak broadening owing to sidewall effect in deep crater.


N In

EDX Mapping

HAADF Image

In Al

N Ga

N is homogeneous through the area analyzed.

Addition of In or Al seems to replace Ga atoms in the GaN.


EDX Line -scanning (at%)

Ga Ga

N NIn In

Al

Multiple Quantum Well, MQW Superlattice

Low concentration of Al and In can be magnified by scale up.


TEM for abrasive analysis – Sample preparation methods

Aggregation status

Cryo-TEM

Nanopipet /TEM

Copper grid: aggregated in drying processes

Native status in solution

Size200 nm100 nm50 nm 500 nm

OM

PrimaryparticleCharacterization

request SecondaryParticle

Unwanted aggregates or big particles

Size & Morphology & Concentration

Wafer defects

CMP performance


[Frozen Liquid] Cryo -TEM – Direct Image

Holey carbon support film

Scale bar: 20 nm

12

43


Particle size distribution

0 20 40 60 80 100 120 1400

5

10

15

20

Par

ticle

num

ber

%

dA (nm)

All particles Circularity < 0.8 Circularity > 0.8

Particle-2

Particle-2 Cluster

* dA = (4A/π)1/2, total calculated n = 1044

53.4 ± 9.9 nm(n = 625)

72.2 ± 16.9 nm (n = 419)

0

10

20

30

40

50

60

Particle-2 Particle -2 Cluster

part

icle

num

ber

(%)

0.2 0.4 0.6 0.8 1.00

2

4

6

8

10

12

Par

ticle

num

ber

%

Circularity

Particle-2 Cluster

Particle-2

20 40 60 80 100 1200.2

0.4

0.6

0.8

1.0

dA (nm)

Circ

ular

ity

Primary particle-2

Circularity = 4ππππ* Area

(Perimeter) 2


Direct Image of Live Liquid in TEM / Direct Image of Live Liquid in TEM / NanopipetNanopipet[K[K --Kit]Kit]

Window and gap of the nanopipet is ~5um, which can b e tailored per research interest.

Scale bar: 100 nm


Comparison, Comparison, CryoCryo --TEM vs. TEM vs. NanopipetNanopipet TEMTEM

0 20 40 60 80 100 120 1400

30

60

90

120

150 Cryo-TEM Nanopipet / TEM

Cou

nted

par

ticle

diameter (nm)


Summary• TEM analysis can be very powerful in structure and composition study.

Recent development of 3D EDX detector empowers this technique to be more efficient and effective.

• By working on advanced ICs, TSV, LED, and CMP slurr y, we have conducted a variety of comparison study with EELS, SIMS, RBS, SEM, and FIB.

• It has been demonstrated there are superior advanta ges of current technology than that of prior art. In addition, obs ervation of wet samples in TEM is feasible now.

advanced methodology of nano device analysis - sematech

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