Download - 2009 Implantation Solution Semilab Group
Implant Process Characterization With Modern In-line Metrologies
July 16, 2009Junction Technology Group, Semicon West 2009 Program
2©2009 Semilab ALL RIGHTS RESERVEDSlide 090716001
Outline
♦ Introduction to Semilab♦ Implant metrology
• Dose• Implant depth • Junction depth• Sheet resistance• Doping profiles• Activated surface dopant density
♦ Will illustrate techniques that provide above parameters♦ Summary
3©2009 Semilab ALL RIGHTS RESERVEDSlide 090716001
Semilab Background
♦ We have brought several powerful techniques into the Semilab family
♦ We offer multiple products for monitoring the implant/anneal processes
♦ The specific customer needs will determine the best fit.
4©2009 Semilab ALL RIGHTS RESERVEDSlide 090716001
The Ion Implant Process
♦ Deposit photo-resist
♦ Expose / develop
♦ Perform blanket implant on product wafers and often monitor wafers also
♦ Measure implant dose, depth
♦ Anneal, to activate dopant
♦ Measure sheet resistance, junction depth, activation, profiles
5©2009 Semilab ALL RIGHTS RESERVEDSlide 090716001
Monitoring Before Anneal
♦ Provides SPC monitoring of implanters and implantation process• Real-time monitoring, immediate feedback
♦ Measures • Dose• Implant Depth
♦ Assumes damage = f(dose)
6©2009 Semilab ALL RIGHTS RESERVEDSlide 090716001
Monitoring After Anneal
♦ The dopant species is activated by the anneal
♦ The activated dopant affects device performance
♦ Measure • Sheet resistance
• Junction depth
• Profiles
7©2009 Semilab ALL RIGHTS RESERVEDSlide 090716001
Obsolete or Timeless?
♦ Before anneal• Therma-Wave (traditional approach)
− Measures in TW units, dependent on energy and dose− Actually measures the damage caused by the implant process
♦ After anneal• 4-Point Probe
− Measures sheet resistance (ohms/square)
8©2009 Semilab ALL RIGHTS RESERVEDSlide 090716001
Semilab Offerings
AnnealIon Implant
Rs JPV
Blanket
Dose Implant depth
BX CI QCS SPV
Activation FastGate
NsurfProduct
DoseProfilesSSM SRP
Hg CV
Junction depth BX CI
Leakage JPV
FastGate JL
Activation SDi NSDBlanket
9©2009 Semilab ALL RIGHTS RESERVEDSlide 090716001
Illuminated
Wd
VSPV ∝ τWd
e
h
Re
Rh
Dark
Bulkp-type
hν
Implant defect levels
Re
RhEF
hνBoth as-implanted and annealed wafersEnergy range: 0.5keV to 3.0MeVDose range: 1E10cm-2 to 5E15cm-2
All common species: B, P, As, BF2,F, He, In, etc.Repeatability: < 1% (for low/medium dose < 0.5%)
Implanted Silicon Annealed Silicon
Implant dose, energy, angle Average doping density
What is Measured?
( ) 2/1)/(ln1sc
iscSPV qN
nNkTehIV
ω∝
NSC – doping concentrationIeh – light intensityω -- light modulation frequency
RNnqkTI
Vdi
ehSPV Δ
=γ
12
Nd – implant induced defect density ΔR -- implant region widthγ -- capture probability
Based on ac-SPV Method
QCS ICT-300Non-Contact Fast Mapping Metrology
10©2009 Semilab ALL RIGHTS RESERVEDSlide 090716001
Implant system A B 5keV 1E15
Implant system B P 45keV 8E14
Implant system C As 3keV 4E15
Implant system D B 5keV 1E15
Implant system E B 2keV 3E15
Implant system F B 0.65keV 1E15
Implanter Micro-Uniformity Detection
Implanter_E Streaming Wafer
1 2 3 4 5 6 7 8 9 10
Implanter_D Streaming Wafer
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
Implanter_C Streaming Wafer
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Implanter_A Streaming Wafer
1 2 3 4 5 6 7 8 9 10 11 12
Av 17116St dev 1.42%
Av 17888St dev 1.94%
Av 18472St dev 1.42%
Av 18160St dev 2.32%
Multi-Implanter SPC: B 31keV 8e12 Correlation to Final Electric TestImplant: As75 2e12 cm-2 300keV
QCSas-implanted
ET
ICT-300 Implant Monitoring Capabilities
11©2009 Semilab ALL RIGHTS RESERVEDSlide 090716001
COCOS (ref. Wilson [1])
VCPD(dark)=VOX+Vsb(+const)
VCPD(light)=VOX(+const)
Vsb= VCPD(dark)- VCPD(light)
ac-SPV (ref. Nakhmanson [2])
2)(2
DA Cq
qkTVsb
NNSD ⋅⋅
−⋅==
ε
SPVD V
IeffconstC⋅
⋅=
ϖ
1. M. Wilson et al., ASTM STP 1382, (1999)2. R. Nakhmanson, Solid State Electron. 18, 617 (1975)
SDI measurement technique and Vsb corrections
SDI independently measures 2 parameters: surface barrier (Vsb) and ac-SPV signal (VSPV)
Implant profile- concentration dependent on depth
depth
conc
entra
tion
SCR depth at Vsb = 250mV
SCR depth at Vsb = 400mV
Measurement depth = Space Charge Region depth WCalibration: NSD versus surface barrier, VSB, dependence is measured and implant specific calibration is introduced.
Measured data corrected for variations in surface barrier, VSB.
C alibration 40keV
y = 4.3E+17x + 2.6E+16R2 = 9.9E-01
y = 5.4E+17x + 2.5E+16R2 = 9.9E-01
y = 6.3E+17x + 3.8E+16R2 = 9.9E-01
8.00E+16
1.00E+171.20E+17
1.40E+171.60E+17
1.80E+17
2.00E+172.20E+17
2.40E+172.60E+17
2.80E+17
0.1 0.2 0.3 0.4 0.5
Surface Barr ie r , Vsb , [V]
Con
cent
ratio
n, [c
m-3
]
2.00e12 cm-22.25e12 cm-22.50e12 cm-2
©2009 Semilab ALL RIGHTS RESERVED
12©2009 Semilab ALL RIGHTS RESERVEDSlide 090716001
NSD Ion implant measurement data
♦ NSD provides excellent day-to-day stability and P/T capability, accounting for variations of wafer surface state.
♦ Dose measurement range : 1x1010 to 1x1014 cm-2; plus higher doses with junction
♦ Software automatically corrects for light reflectivity due to oxide films.
NSD repeatability
4.000E+14
4.400E+14
4.800E+14
5.200E+14
5.600E+14
6.000E+14
0 2 4 6 8 10 12 14
Run Number
Dop
ing
Con
cent
ratio
n
Average: 5.0843 e14 cm-3
StdDev: 3.3374 e11 cm-3
StdDev%: 0.07%
y = 35989x + 1E+16R2 = 0.9989
0.0E+00
5.0E+16
1.0E+17
1.5E+17
2.0E+17
2.5E+17
3.0E+17
0.E+00 1.E+12 2.E+12 3.E+12 4.E+12 5.E+12 6.E+12 7.E+12 8.E+12
Implanted dose (at/cm2)
NSD
(at/c
m3 )
Outstanding measurementPrecision (P/T)
25keV P implant – correlation vs dose
500keV P implantDose: 5E12(0, 0) angle
Includes full wafer mapping capability
13©2009 Semilab ALL RIGHTS RESERVEDSlide 090716001
MBIR USJ Data Analysis
♦ Refractive index of the doped layer was calculated using Drude model, and rectangular profile of the concentration.
♦ Model fit was performed with three varied parameters: doped layer thickness, activated carrier concentration and carrier mobility.
♦ Wavenumber range used : 600-7000 cm-1.
14©2009 Semilab ALL RIGHTS RESERVEDSlide 090716001
MBIR Correlation With Reference Methods
• MBIR 1/Rs is calculated as the product of the mobility μ and activated dopant dose (times the electron charge): •1/Rs=eμDose
y = 0.7409xR2 = 0.9938
0
0.002
0.004
0.006
0.008
0 0.002 0.004 0.006 0.008 0.01
1/sheet resistance, 4pt. probe (1/ohm)
1/sh
eet r
esis
tanc
e, M
BIR
(1/o
hm)
samples 1-7samples 8-9
y = 1.1294xR2 = 0.9923
0
20
40
60
80
100
120
140
0 20 40 60 80 100 120 140SIMS junction depth (nm)
MB
IR th
ickn
ess
(nm
)
0
2E+14
4E+14
6E+14
8E+14
1E+15
1.2E+15
1.4E+15
1.6E+15
0 0.002 0.004 0.006 0.008 0.01
1/sheet resistance, 4pt probe (1/ohm)
MB
IR d
ose
(1/c
m2 )
samples 1-7samples 8-9
Sheet ResistanceDoped Layer Thickness
Activated Dopant Dose
15©2009 Semilab ALL RIGHTS RESERVEDSlide 090716001su
rface
pot
entia
l
position on wafer relative to excitation LED (r)
2 concentriccapacitive electrodes
pulsed LED
rRIIdR
rU s
s π2−=−=
∂∂
⎟⎟⎠
⎞⎜⎜⎝
⎛⎟⎟⎠
⎞⎜⎜⎝
⎛+−−Θ=
∂∂ UCi
RrrJr
rI
dd
ωπ 1)(2 0
0)( 02
2
22 =−Θ+⎟⎟
⎠
⎞⎜⎜⎝
⎛+−
∂∂
+∂∂ rrJUCRi
RRr
rUr
rUr ds
d
s ω
Principle of JPV Sheet Resistance MeasurementsPrinciple of JPV Sheet Resistance Measurements
♦ Junction Photovoltage-based sheet resistance measurement: a method for non-contact implant monitoring with high-resolution mapping capability.
♦ Basic principle:• e- and hole generation by chopped LED
light• This causes change in junction voltage• Change spreads laterally, and the
attenuation depends on sheet resistance• Change of the potential is picked up by
capacitive sensors• Signal depends strongly on LED
chopping frequency (f)• Rs, Cd and Rd (Jleak) are calculated by
fitting the theoretical JPV signal
♦ Potential spreading
♦ Current spreading
♦ Equation to solve to obtain Rs
16©2009 Semilab ALL RIGHTS RESERVEDSlide 090716001
JPV Sheet Resistance MeasurementsJPV Sheet Resistance Measurements
Applications and specifications♦ Implant process control (Rs depends on dose
and energy) on various implant types: USJ, deep implant, pocket implant, plasma immersion implant, etc.
♦ Dose range: >5E11cm-2
♦ Species: B, P, As, BF2, etc.
Sheet Resistance and Leakage Current Mapping
♦ Visualization of non-uniformities, implanter errors (striping, etc.) which are not detectable by low resolution methods
♦ Detects variations and inhomogeneities smaller than 1 % of the wafer average
♦ Works on oxidized and non-oxidized wafers
JPV – 4PP correlation:•Same wafer.•Top half is 4PP map (625 points)•Bottom half is JPV map (17,000 points)•Both maps takethe same time to make.
3100
3200
3300
3400
3500
3600
3700
1 2 3 4 5 6 7 8 9 10
Repeatability test on 3 different wafersRepeatability < 0.2 %
Slot 1
Slot 2
Slot 3
17©2009 Semilab ALL RIGHTS RESERVEDSlide 090716001
Principle of Carrier Illumination TechnologyPrinciple of Carrier Illumination Technology
Objective lens
Generation laser(830 nm red)
Probe laser(980 nm IR)
Beam splitter
CognexPatMaxVision system
Detector
2-um spot size
Junction
Excess carriers
Beam
• Generation laser creates excess carriers and, where significant damage is present, heat.
• Excess carrier gradient forms index of refraction gradient
• Probe laser uses index of refraction gradient or surface heat to determine junction depth, dose level or PAI depth.
• Generation laser is modulated (2kHz) to enable high signal/noise ratio.
18©2009 Semilab ALL RIGHTS RESERVEDSlide 090716001
-12540
-12500
-12460
-12420
-12380
-12340
1.2E+15 1.3E+15 1.4E+15 1.5E+15 1.6E+15 1.7E+15Dose (cm-2)
BX
Sign
al(u
V)
Dose response on BF2 implant
Carrier Illumination TechnologyCarrier Illumination Technology
♦ Implant monitoring• Dose range: 1x1010 cm-2 to 1x1016 cm-2
• Energy range: 100 eV to 3 MeV• Species: As, B, P, BF2, In, Sb
♦ PAI depth• Depth range10 nm to 100 nm
♦ Junction depth measurement• Depth range:10 to 70 nm
♦ Scope applications for development:• Measurement on SOI substrates • Cu (metal) via structures measurement• Integration with Semilab JPV method
Measurements on Boron implanted wafers
19©2009 Semilab ALL RIGHTS RESERVEDSlide 090716001
Contact Probing MetrologySSM-Hg CV SSM FastGate® CV SRP
SSM 2000
..................
97-7rgm201
20©2009 Semilab ALL RIGHTS RESERVEDSlide 090716001
Contact Probing Metrology
1.E+10
1.E+11
1.E+12
1.E+13
1.E+14
1.E+15
1.E+16
1.E+17
1.E+18
0 2 4 6 8 10 12 14
Depth (mm)
Car
rier D
ensi
ty (c
m-3
)
SOI 1 SOI 2
n
p
oxide
n
n
Freescale ISPSD06
SOI
©2009 Semilab ALL RIGHTS RESERVED
21©2009 Semilab ALL RIGHTS RESERVEDSlide 090716001
Ion Implant Matrix-Sensitivity
Ion Implant Metrology Sensitivity
1E+2
1E+3
1E+4
1E+5
1E+6
1E+7
1E+9
1E+10
1E+11
1E+12
1E+13
1E+14
1E+15
1E+16
1E+17
1E+18
1E+19
Ion Dose (cm-2)
Ion
Ener
gy (e
V)
0.0
0.2
0.4
0.6
0.8
1.0
Sens
itivi
ty (Δ
sig
nal/Δ
dos
e)
Super deep w ell(CCD)
Halo
S-D extension
Retrograde Channel
Mid w ell(punch-
thru)
Deep w ell(latch up)
SIMOX
Channel
S-D contact
pSi gate
4PP
CV surface
ThermaWave
JPV
ac-SPV
22©2009 Semilab ALL RIGHTS RESERVEDSlide 090716001
Ion Implant Matrix-Range
Ion Implant Metrology Range
1E+2
1E+3
1E+4
1E+5
1E+6
1E+7
1E+9
1E+10
1E+11
1E+12
1E+13
1E+14
1E+15
1E+16
1E+17
1E+18
1E+19
Ion Dose (cm-2)
Ion
Ener
gy (e
V)
Super deep well(CCD)
Halo
S-D extension
Retrograde Channel
Mid well(punch-
thru)
Deep well(latch up)
SIMOX
Channel
S-D contact
pSi gateCV surface
JPV
SRP
ac-SPV
23©2009 Semilab ALL RIGHTS RESERVEDSlide 090716001
Case Study-AVS Insight ‘09
Former QCS
Former SSM
Former competitors learning that their techniquesare complementary in many areas. The winner in this case study is the metrology end user.
24©2009 Semilab ALL RIGHTS RESERVEDSlide 090716001
Summary
♦ We have brought several powerful techniques into the Semilab family
♦ We offer multiple products for monitoring the implant/anneal processes
♦ We look forward to discussion of your needs to find the best fit.