SEMATECH AEC/APC Symposium XIISept 24-28, 2000, Lake Tahoe, Nevada
24.05.2000Page 1
Jan ZimpelKnut VoigtländerFraunhofer InstitutIVI DresdenAndreas SteinbachInfineon DresdenDirk KnoblochInfineon München
Jan ZimpelKnut Voigtländer
Fraunhofer IVI DresdenAndreas Steinbach
Infineon Technologies DresdenDirk Knobloch
Infineon Technologies München
Using Multi Way PCA (MPCA) forAdvanced Monitoring and Diagnosis
for Plasma Processing based onOptical Emission Spectroscopy
SEMATECH AEC/APC Symposium XIISept 24-28, 2000, Lake Tahoe, Nevada
24.05.2000Page 2
Jan ZimpelKnut VoigtländerFraunhofer InstitutIVI DresdenAndreas SteinbachInfineon DresdenDirk KnoblochInfineon München
Acknowledgement
The authors of this presentationwould like to thank
Siegfried BernhardLars ChristophBarbara SchmidtInfineon Technologies Dresden
SEMATECH AEC/APC Symposium XIISept 24-28, 2000, Lake Tahoe, Nevada
24.05.2000Page 3
Jan ZimpelKnut VoigtländerFraunhofer InstitutIVI DresdenAndreas SteinbachInfineon DresdenDirk KnoblochInfineon München
Outline
� Introduction - APC in high volume production� Hardware integration and software structure� Data reduction by PCA� Experiments
– Contact etch at AMAT MxP+– Poly etch at AMAT DPS
� Summary and outlook
SEMATECH AEC/APC Symposium XIISept 24-28, 2000, Lake Tahoe, Nevada
24.05.2000Page 4
Jan ZimpelKnut VoigtländerFraunhofer InstitutIVI DresdenAndreas SteinbachInfineon DresdenDirk KnoblochInfineon München
APC - offline analysis andreal time process control including alarms
ToolParameters
ProcessParameters
ProductParameters
Data Base Offline AnalysisModel
Logistic Data(Wafer, Recipe)
Real TimeMonitoring Online Alarm
APC in high volume production
SEMATECH AEC/APC Symposium XIISept 24-28, 2000, Lake Tahoe, Nevada
24.05.2000Page 5
Jan ZimpelKnut VoigtländerFraunhofer InstitutIVI DresdenAndreas SteinbachInfineon DresdenDirk KnoblochInfineon München
Data reduction – an essential needfor APC in high volume production
� APC in high volume production creates large amounts of data� Data reduction is an essential need for off line analysis
and real time process monitoring� Methods for data reduction:
– Measurement techniques based on physical models– Calculation of statistical key numbers– Use of complex process parameters– Model based data analysis
APC in high volume production
SEMATECH AEC/APC Symposium XIISept 24-28, 2000, Lake Tahoe, Nevada
24.05.2000Page 6
Jan ZimpelKnut VoigtländerFraunhofer InstitutIVI DresdenAndreas SteinbachInfineon DresdenDirk KnoblochInfineon München
Features of Hamamatsu MPM spectrometer
� Spectral range: 200 - 950 nm� Resolution: < 2 nm� CCD line channels: 1024� Connection to Host PC
via TCP-IP, RS 232� Internal data processing for endpoint
detection; up to 100 endpoint scrip‘s areavailable
� Digital / analog port‘s for connection to tool
Hardware integration and software structure
SEMATECH AEC/APC Symposium XIISept 24-28, 2000, Lake Tahoe, Nevada
24.05.2000Page 7
Jan ZimpelKnut VoigtländerFraunhofer InstitutIVI DresdenAndreas SteinbachInfineon DresdenDirk KnoblochInfineon München
Integration of Hamamatsu MPM spectrometer
FAB-LAN
Plasma
Equipment
SECS SECSTICSpassthrough
server
EquipmentManager
start / stop spectrarecipe
process steplot number
winsockprotocol
application software
tool endpointinterface
� Tool interface for stand alone endpoint detection
� Interface for logistic datae.g., lot and wafer number, recipe, step number
Hardware integration and software structure
SEMATECH AEC/APC Symposium XIISept 24-28, 2000, Lake Tahoe, Nevada
24.05.2000Page 8
Jan ZimpelKnut VoigtländerFraunhofer InstitutIVI DresdenAndreas SteinbachInfineon DresdenDirk KnoblochInfineon München
Software solution developed byFraunhofer Institut IVI Dresden
A p p l i c a t i o nprocess
database
measurementcomponent
singlespectrumanalysis
multiplespectrumanalysis
endpointsynthesis
tool
modeldatabase
on-linemonitoring
tool
FAB LAN
spectral data fromMPM
start /stop measurement
MatlabServer
�Database oriented spectrastorage and SQL- baseddata access for:
- Data visualization- Data analysis- Endpoint synthesis- Validation of endpoint
detection algorithms
Hardware integration and software structure
SEMATECH AEC/APC Symposium XIISept 24-28, 2000, Lake Tahoe, Nevada
24.05.2000Page 9
Jan ZimpelKnut VoigtländerFraunhofer InstitutIVI DresdenAndreas SteinbachInfineon DresdenDirk KnoblochInfineon München
Data reduction by key number calculationwith PCA
� Simple key number extraction:mean, standard deviation, max, min, ...
� Extraction of key numbers using signal decomposition:– Tschebyscheff functions– Adjusted signal base (PCA)
Multivariate key number extraction -- Multi Way PCA� Adaptation of a nonlinear parametric signal model� Compromise between efficiency and effort / a-priori knowledge
Data reduction by PCA
SEMATECH AEC/APC Symposium XIISept 24-28, 2000, Lake Tahoe, Nevada
24.05.2000Page 10
Jan ZimpelKnut VoigtländerFraunhofer InstitutIVI DresdenAndreas SteinbachInfineon DresdenDirk KnoblochInfineon München
ntR ××λ∈Λ
Principle of PCA – Data cube
� Optical spectra visualized as a „Data cube“� Optical emission spectroscopy creates very large amounts of data !
wavelength λλλλwafer 1 ... n
Vertical and horizontal cutthrough Data cube
etch
tim
e t
wavelength λ
time
Data cubecontaining spectra
Data reduction by PCA
SEMATECH AEC/APC Symposium XIISept 24-28, 2000, Lake Tahoe, Nevada
24.05.2000Page 11
Jan ZimpelKnut VoigtländerFraunhofer InstitutIVI DresdenAndreas SteinbachInfineon DresdenDirk KnoblochInfineon München 350 400 450 500 550 600 650 700 750
1
2
3
4
5
6
x 105
m11
m21
m31
m19
m29
m39
Principle of PCA – Matrix calculation
� Split of the original data matrix into orthogonal pattern ui andorthogonal scores mi:
� Scores represent the weight of the corresponding pattern in theoriginal data sample
⋅=⋅=i iuimTUMX T
350 400 450 500 550 600 650 7000
0.05
0.1
0.15
300 350 400 450 500 550 600 650 700-0.15
-0.1-0.05
00.05
300 350 400 450 500 550 600 650 700-0.2
0
0.2
wavelength
original data: X scores: mi base pattern: ui
Data reduction by PCA
SEMATECH AEC/APC Symposium XIISept 24-28, 2000, Lake Tahoe, Nevada
24.05.2000Page 12
Jan ZimpelKnut VoigtländerFraunhofer InstitutIVI DresdenAndreas SteinbachInfineon DresdenDirk KnoblochInfineon München
Application of PCA on DRAM contact etchat Applied Materials MXP+ chamber� Contact etch at Applied Materials MxP+ chamber� Standard oxide etch chemistry, CF4, CHF3, Ar� Observation of 5 wet clean cycles (WC), about 4000 wafers� Simple process mix, two different recipes for two high volume
DRAM products mainly
Step Product 1 Product 2 Descum -- N2 / O2 descum Main etch 1 BPSG etch BPSG etch Main etch 2 -- Nitride etch
Contact etch in AMAT MxP+
SEMATECH AEC/APC Symposium XIISept 24-28, 2000, Lake Tahoe, Nevada
24.05.2000Page 13
Jan ZimpelKnut VoigtländerFraunhofer InstitutIVI DresdenAndreas SteinbachInfineon DresdenDirk KnoblochInfineon München
3 0 0 3 5 0 4 0 0 4 5 0 5 0 0 5 5 0 6 0 0 6 5 0 7 0 0 7 5 0-0 .2 5
-0 .2
-0 .1 5
-0 .1
-0 .0 5
0
0 .0 5
0 .1
0 .1 5
w a ve le n g th [n m ]
norm
. Int
ensi
tät
W C 2
3 0 0 3 5 0 4 0 0 4 50 5 0 0 5 5 0 6 0 0 6 5 0 7 0 0 7 50-0 .1 5
-0 .1
-0 .0 5
0
0 .0 5
0 .1
0 .1 5
0 .2
0 .2 5
w a ve le n g th [n m ]
norm
. Int
ensi
tät
W C 2
PCA results obtained on DRAM contact etchat Applied Materials MXP+ chamber
300 400 500 600 700 800 9000
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Matrix X: mean spectraof 4000 wafersof 5 wet clean cycles (WC)
3 0 0 3 5 0 4 0 0 4 5 0 5 0 0 5 5 0 6 0 0 6 5 0 7 0 0 7 5 00
0 .0 5
0 .1
0 .1 5
0 .2
0 .2 5
w a ve le n g th [n m ]
norm. Intensität
W C 2
PCA
1st order
3 0 0 3 5 0 4 0 0 4 5 0 5 0 0-6 0 0 0
-5 0 0 0
-4 0 0 0
-3 0 0 0
-2 0 0 0
-1 0 0 0
0
1 0 0 0
2 0 0 0
3 0 0 0
4 0 0 0W C 2W C 3W C 4W C 5
0 1 00 2 00 30 0 4 00 5 00 60 0 7 00 8 00 90 0-8
-6
-4
-2
0
2
4
6x 1 0
4
W C 2W C 3W C 4W C 5
wavelength [nm]
Inte
nsity
[arb
. uni
ts] stacked
mean spectraof 4000 wafers
3rd order
2nd order
0 2 0 0 4 0 0 6 0 0 8 0 0 1 0 0 0
2 .2
2 .4
2 .6
2 .8
3
3 .2
3 .4
x 1 05
W C 2W C 3W C 4W C 5
wavelength [nm]
Inte
nsity
[arb
. uni
ts]
wafer
scor
es [c
ount
s]
Patterns and scores 1st to 3rd order of WC 2 .. 5
1st order
2nd order
3rd order
Contact etch in AMAT MxP+
SEMATECH AEC/APC Symposium XIISept 24-28, 2000, Lake Tahoe, Nevada
24.05.2000Page 14
Jan ZimpelKnut VoigtländerFraunhofer InstitutIVI DresdenAndreas SteinbachInfineon DresdenDirk KnoblochInfineon München
PCA results obtained on contact etch atApplied Materials MXP+ chamber, cont.� CF4, CHF3, Ar chemistry, two main DRAM products� Scores of 2st order of the first observed at wet clean cycle 1
� Product 1: high polymerizingProduct 2: low polymerizing
� Scores of 2st order decreaseduring WC1, caused by:
- Increasing light absorption atpolymer layer on the recessside window
- And real process drift causedby polymer on chamber wall
� Product dependent monitoringof chamber conditionrf hours [h]
scor
es [c
ount
s]
scores of 2st order vs. rf hours
product 1
product 2product 3
one point – one wafer
Contact etch in AMAT MxP+
SEMATECH AEC/APC Symposium XIISept 24-28, 2000, Lake Tahoe, Nevada
24.05.2000Page 15
Jan ZimpelKnut VoigtländerFraunhofer InstitutIVI DresdenAndreas SteinbachInfineon DresdenDirk KnoblochInfineon München
Multi-Way Principle Component Analysis
N1,...,n for
(t)jv)(iui j
n)j,M(i,
=
′λ⋅
� “One way PCA”: use of one mean spectrum per wafer� Multi Way PCA: Calculation of orthogonal wave pattern ui
and orthogonal base time signals vi by unfolding the originaldata cube in time and wave direction
ntR ××λ∈Λ
wavelength λλλλwafer 1 ... net
ch ti
me t
Data reduction by Multi Way PCA
SEMATECH AEC/APC Symposium XIISept 24-28, 2000, Lake Tahoe, Nevada
24.05.2000Page 16
Jan ZimpelKnut VoigtländerFraunhofer InstitutIVI DresdenAndreas SteinbachInfineon DresdenDirk KnoblochInfineon München
50 100 150
0.12
0.121
0.122
50 100 150
-0.1
0
0.1
0.2
50 100 150
-0.2
0
0.2v1 v2v3
400 500 600 700-0.1
0
0.1
300 400 500 600 700-0.1
0
0.1
0.2
300 400 500 600 700-0.05
00.050.1
0.15
300 400 500 600 700-0.1
0
0.1
wavelength [nm ]
u2
u3
u4
u5
Some examples of key numbers obtained byMulti Way PCA on contact etch at AMAT MxP+
extra
cted
bas
ic wa
ve p
atte
rn u
i
resulting key numbers vs. wafer
extractedbasic time signals vj
wafer
scor
es o
f key
num
ber u
iv j [cou
nts]
Contact etch in AMAT MxP+
SEMATECH AEC/APC Symposium XIISept 24-28, 2000, Lake Tahoe, Nevada
24.05.2000Page 17
Jan ZimpelKnut VoigtländerFraunhofer InstitutIVI DresdenAndreas SteinbachInfineon DresdenDirk KnoblochInfineon München
Interpretation of key numbers ui;vj
� Significant signatures up to10th…20th order of ui and vj, max. about 100...400 key numbers
� Significant key numbers limited by:– increasing order
decreasing information content– redundant signatures
� PCA = mathematical algorithm, nophysical or technological input
� Advantage: universal, applicationto any kind of data possible
� Disadvantage: no clear physicalmeaning of these key numbers
� Difficult interpretation
Contact etch in AMAT MxP+
� Interpretation of key numbers with help of:– Physical, chemical, technological knowledge– Comparison to other measurement techniques,
delivering physical parameters
SEMATECH AEC/APC Symposium XIISept 24-28, 2000, Lake Tahoe, Nevada
24.05.2000Page 18
Jan ZimpelKnut VoigtländerFraunhofer InstitutIVI DresdenAndreas SteinbachInfineon DresdenDirk KnoblochInfineon München
Interpretation of optical key numberswith experience
� Key number u2;v1 showsreproducible long term driftbetween wet cleans.
� Experience possible reasons:– Light adsorption by polymer,
growing on recess side window– Drift of gas composition,
caused by polymer on thechamber walls
� No influence of power dissipationhere
wafer
key n
umbe
r [co
unts
]key number u2;v1 vs. wafer
one point –one wafer
Contact etch in AMAT MxP+
SEMATECH AEC/APC Symposium XIISept 24-28, 2000, Lake Tahoe, Nevada
24.05.2000Page 19
Jan ZimpelKnut VoigtländerFraunhofer InstitutIVI DresdenAndreas SteinbachInfineon DresdenDirk KnoblochInfineon München
Reference: Plasma parameter measurementwith SEERS
� SEERS = Self Excited Electron PlasmaResonance Spectroscopy= „electrical“ plasma measurement technique
� Measurement of:– rf current– rf voltage
� Real time calculation of plasma parameters:– Electron collision rate [collisions per sec]– Electron density [electrons per cm³]– Bulk power [mW per cm²]– DC bias voltage [V]
� Plasma monitoring system HERCULES, basedon SEERS was used as reference system
FFT
rf currentrf voltage
Model SEERS
Electron collision rateElectron density
Bulk powerDC bias voltage
Contact etch in AMAT MxP+
SEMATECH AEC/APC Symposium XIISept 24-28, 2000, Lake Tahoe, Nevada
24.05.2000Page 20
Jan ZimpelKnut VoigtländerFraunhofer InstitutIVI DresdenAndreas SteinbachInfineon DresdenDirk KnoblochInfineon München
0 50 100 150 200 250 300-1
0
1
2
x 104
50 100 150 200 250 300-1
0
1
2
3
x 104
wafer
key n
umbe
r [co
unts
]
wafer
key number ui;vj vs. wafer
one point – one wafer
Interpretation of optical key numberswith comparison to plasma parameters
� Short term drift indicated by:– Optical key numbers,
e.g., u4;v1, u5;v1– Electron collision rate
electron collision rate vs. rf hours
9,2
9,4
9,6
9,8
10,0
10,2
15 20 25 30
rf hours [h]co
llisi
on ra
te [1
0 7 s -1
]
one point –one wafer
� Possible reasons:– Temperature drift– Gas adsorption and desorption
Contact etch in AMAT MxP+
SEMATECH AEC/APC Symposium XIISept 24-28, 2000, Lake Tahoe, Nevada
24.05.2000Page 21
Jan ZimpelKnut VoigtländerFraunhofer InstitutIVI DresdenAndreas SteinbachInfineon DresdenDirk KnoblochInfineon München
wafer
key n
umbe
r [co
unts
]
one point – one wafer
key number u4;v2 vs. wafer
Product 1
Product 2
Interpretation of optical key numbers withcomparison to plasma parameters, cont.
� Product indicated by:– Optical key number u4;v2
(no optical measurements available during the tool failure)
– Electron density
� Reason:– Different open area
of 2 products
electron density vs. rf hours
9
10
11
12
260 310 360 410
rf hours [h]el
ectr
on d
ensi
ty [1
08 /cm
3 ] WC3WC4WC5
Wetclean
one point – one lot
Tool failuredetected (Arcing)
Product 1Product 2
Contact etch in AMAT MxP+
SEMATECH AEC/APC Symposium XIISept 24-28, 2000, Lake Tahoe, Nevada
24.05.2000Page 22
Jan ZimpelKnut VoigtländerFraunhofer InstitutIVI DresdenAndreas SteinbachInfineon DresdenDirk KnoblochInfineon München
2 0 4 0 6 0 8 0 1 0 0 1 2 0
-1 0 0 0
-8 0 0
-6 0 0
-4 0 0
-2 0 0
0
2 0 0
4 0 0
wafer
key n
umbe
r [co
unts
]key number u5;v6 vs. wafer
etch time
optic
al in
tens
ity [a
rb. u
nits
]
optical endpoint signal vs. etch time
one point –one wafer
•10 •20 •30 •40 •50 •60
•0.96
•0.97
•0.98
•0.99
•1
•1.01
•1.02
•1.03
•1.04
•1.05
•x 10•4
one curve –one wafer
Interpretation of optical key numbers withcomparison to endpoint signatures
� Key number u5;v6 corresponds with endpoint time� Superimposition of previous processes, depending on lot
Contact etch in AMAT MxP+
SEMATECH AEC/APC Symposium XIISept 24-28, 2000, Lake Tahoe, Nevada
24.05.2000Page 23
Jan ZimpelKnut VoigtländerFraunhofer InstitutIVI DresdenAndreas SteinbachInfineon DresdenDirk KnoblochInfineon München
Topical Example: Chamber comparison atpoly recess etch in Applied Materials DPS
� Measurement atchamber B severalweeks later.
� Key numbers indicateother conditions atchamber B (see 3).
� Reasons not yetidentified.
Poly recess etch in AMAT DPS
wafer wafer
key n
umbe
r [co
unts
]key numbers vs. wafer
Chamber A Chamber B1
3
2
1
2
3one point – one wafer
SEMATECH AEC/APC Symposium XIISept 24-28, 2000, Lake Tahoe, Nevada
24.05.2000Page 24
Jan ZimpelKnut VoigtländerFraunhofer InstitutIVI DresdenAndreas SteinbachInfineon DresdenDirk KnoblochInfineon München
Summary and outlook
� PCA / MPCA is a universal mathematical method for data analysis and datareduction.
� Key numbers obtained by application of PCA / MPCA on optical spectra arecomplex process parameters, indicating tool and wafer impacts.
� Interpretation of key numbers is possible by use of:– extracted spectral wave pattern and basic time signals– physical, chemical, technological knowledge– comparison to other process parameters and tool parameters
� Actual evaluation / application status:– Endpoint detection demonstrated at contact etch processes– Application for optimization of endpoint signals and clean processes
� Use for real time process control in high volume production is a greatchallenge, due to large number of key numbers and complex interpretation.
Summary
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