Workshop on Self Excited Electron Plasma Resonance Spectroscopy8. - 9. June 1999 at Infineon Technologies Dresden - 1 - P. Höhmann
Infineon Regensburg
Plasma diagnostic at LAM TCP 9600SETM
H. Steinmetz, J. Strobl, N. Rohn and T. Werner, Lam Research GmbH
M. Klick, W. Rehak, M. Kammeyer, and D. Suchland, Adolf-Slaby-Institute
S. Wurm, W. Preis and Ch. Koelbl, Infineon Technologies
Plasma diagnostic in an inductively coupled plasma using chlorine chemistry
Workshop on Self Excited Electron Plasma Resonance Spectroscopy8. - 9. June 1999 at Infineon Technologies Dresden - 2 - P. Höhmann
Infineon Regensburg
Plasma diagnostics for production toolsComparison of complementary methods
Optical emission Self excited electron VI - probespectroscopy (OES) resonance spectroscopy (rf voltage and power)
(SEERS), Hercules______________________________________________________________________________________________________
Parameters - relative values - absolute values - absolute and relative values- line averaged - volume averaged - no well define averaging
- intensities of emission lines - plasma bulk power - peak voltage- identification of species - plasma density - real power in chamber- characterization of excitation - electron collision rate (not in plasma)
Measurement - optical - electrical, high frequency - electrical, radio frequency- passive - passive - passive- non-intrusive - non-intrusive - non-intrusive
Deposition,contamination - critical - no influence - no influence
Sensitivity - high - high - low/medium
Endpoint - yes - yes - (strongly) limited
Base lining, - strongy limeted - yes - limitedtool matching
Plasma diagnostic at LAM TCP 9600SETM
Plasma diagnostics for production tools
Workshop on Self Excited Electron Plasma Resonance Spectroscopy8. - 9. June 1999 at Infineon Technologies Dresden - 3 - P. Höhmann
Infineon Regensburg
Plasma diagnostic at LAM TCP 9600SETM
Oil
13.56 million rps(generator)
Sheath(nonlinear part)
Sheath(linear part
- retarding electric field)
Inert massof plasmaelectrons
Collisionswith neutrals
Sinusoidal oscillation(simple sheath model)
Nonsinusoidal oscillation(realistic sheath model)
Mechanical analogon of nonlinear effect used for SEERS
Workshop on Self Excited Electron Plasma Resonance Spectroscopy8. - 9. June 1999 at Infineon Technologies Dresden - 4 - P. Höhmann
Infineon Regensburg
Plasma diagnostic at LAM TCP 9600SETM
rf current
HERCULES
Coaxial sensor and cable
TCP coil
Process data bank
SEERS
Fast ADC500 MHz, 1 GS/s
50 Ohms input
dielectricwindow
chamber
bottom power
peak voltage
top power
plasma
Experimental setup
Workshop on Self Excited Electron Plasma Resonance Spectroscopy8. - 9. June 1999 at Infineon Technologies Dresden - 5 - P. Höhmann
Infineon Regensburg
Plasma diagnostic at LAM TCP 9600SETM
TM®HERCULES - Sensor for LAM TCP 9600SE
Workshop on Self Excited Electron Plasma Resonance Spectroscopy8. - 9. June 1999 at Infineon Technologies Dresden - 6 - P. Höhmann
Infineon Regensburg
Plasma diagnostic at LAM TCP 9600SETM
TM®
Figure 1 shows window plate of the TCP-System in section
Detail figure: mounted sensor in the He leakage flange (principle)
He leakage flange
Contact spring or threadA
HERCULES - Sensor for LAM TCP 9600SE
Workshop on Self Excited Electron Plasma Resonance Spectroscopy8. - 9. June 1999 at Infineon Technologies Dresden - 7 - P. Höhmann
Infineon Regensburg
Plasma diagnostic at LAM TCP 9600SETM
0 0.5 1 1.5 2 2.5process time [min]
0
2.109
4.109
6.109
8.109
elec
tron
dens
ity [c
m-3
]
15 mTorr15 mTorr10 mTorr10 mTorrfirst wafer (cold machine)first wafer (cold machine)13 mTorr13 mTorr
, ,
The relative changes betweenprocessing a production waferon a warm and a cold machine as well as between running process at different total pressure are much more evident.
The overall curve shape does depend strongly on total pressure and on tool condition.
Pressure variation
Workshop on Self Excited Electron Plasma Resonance Spectroscopy8. - 9. June 1999 at Infineon Technologies Dresden - 8 - P. Höhmann
Infineon Regensburg
Plasma diagnostic at LAM TCP 9600SETM
0 100 200 300 400process time [s]
0
109
2.109
3.109
4.109
5.109
6.109
7.109
8.109
elec
tron
dens
ity [1
/cm
3 ], co
llisio
n ra
te [1
/s
60
90
120
150
peak
vol
tage
[V]
peak voltagecollision rateelectron density(filtered)
Process signaturesof the first three wafers
Al etching - first wafer effect
Workshop on Self Excited Electron Plasma Resonance Spectroscopy8. - 9. June 1999 at Infineon Technologies Dresden - 9 - P. Höhmann
Infineon Regensburg
Plasma diagnostic at LAM TCP 9600SETM
100 200 300 400 500 6002
46810
20
406080100
bulk
pow
er P
BP [m
W c
m-2
]
100 W100 W150 W150 W200 W200 W
100 200 300 400 500 600TCP - power PTCP [ W ]
109
2
468
1010
elec
tron
dens
ity n
e [cm
-3]
TCP power effects thedensity and collision rate ofelectrons and therefore theplasma impedance and thepower dissipation of thebottom power (capacitive).
Mainly dependent oncollision rate, the bulk power(bottom) decreases forincreasing TCP power(>250W). This is the reasonfor the plateau in the electrondensity.
Electron density and bulk power vs. TCP power
Workshop on Self Excited Electron Plasma Resonance Spectroscopy8. - 9. June 1999 at Infineon Technologies Dresden - 10 - P. Höhmann
Infineon Regensburg
Plasma diagnostic at LAM TCP 9600SETM
Product wafer - resist mask on Al (appr. 50%)
0 40 80 120 160process time [s]
3.109
4.109
5.109
6.109
7.109
8.109
elec
tron
dens
ity [1
/cm
3 ]
first waferfirst wafer
third waferthird wafer
secondsecond
main etchmain etch
The behavior of the mainetch for the first wafer ofa lot is quite different fromthe following ones.
Al etching in Cl2 - first wafer effect
Workshop on Self Excited Electron Plasma Resonance Spectroscopy8. - 9. June 1999 at Infineon Technologies Dresden - 11 - P. Höhmann
Infineon Regensburg
Plasma diagnostic at LAM TCP 9600SETM
Fault: no resist, faultless dashed (reference wafer)
20 40 60 80 100 120 140 160process time [s]
468
10
20
406080
100
200
peak
vol
tage
[V]
106
5
107
5
108
5
109
colli
sion
rate
[1/s]
100
500
1000
5000
10000
optic
al e
miss
ion
(EP)
The break-throughis not influenced(here separate step).
In case of the main etch thecollision rate decreases byone order of magnitude.
Wafer fault analysis
Workshop on Self Excited Electron Plasma Resonance Spectroscopy8. - 9. June 1999 at Infineon Technologies Dresden - 12 - P. Höhmann
Infineon Regensburg
Plasma diagnostic at LAM TCP 9600SETM
each curve averaged from five test wafers
0 20 40 60 80 100 120process time [s]
0
107
2.107
3.107
4.107
5.107
colli
sion
rate
[1/s]
with TiN (100 nm), Ti (15 nm)with TiN (100 nm), Ti (15 nm)
Ti layerTi layer
800 nm AlSiCu800 nm AlSiCu
break through (Al2O3)break through (Al2O3)
SiO2SiO2
Increase of the collision rate due tothe larger cross section of Ti (red curve).
TiN layer not visible.
Al etching-with/without barrier (TiN,Ti)
Workshop on Self Excited Electron Plasma Resonance Spectroscopy8. - 9. June 1999 at Infineon Technologies Dresden - 13 - P. Höhmann
Infineon Regensburg
Plasma diagnostic at LAM TCP 9600SETM
0 7 14 21 28 35 42Wafer No.
1.2.107
1.5.107
1.8.107
2.1.107
2.4.107
2.7.107
3.107
colli
sion
rate
[1/s] resist wafer (*0.7)resist wafer (*0.7)
Si wafer (*2)Si wafer (*2)product waferproduct wafer
First Si wafer (blue curve) after chambercleaning behaves different.
Conditioning is finished after processing10 resist wafers.
Deconditioning due to processing bare Siwafers.
Charactrization and calibration of machinestatus possible by measuring andcomparing absolute parameter values.
Characterization of chamber cleaning
Workshop on Self Excited Electron Plasma Resonance Spectroscopy8. - 9. June 1999 at Infineon Technologies Dresden - 14 - P. Höhmann
Infineon Regensburg
Plasma diagnostic at LAM TCP 9600SETM
one lot one point
After Cl2-MFC adjust-ments/substitution, thecollision rate returnedback to normal signallevels.
Shows the dramatic effectof the main clean on thecollision rate.
The endpoint level wasadjusted during cleaningprocedures.3640 3710 3780 3850 3920 3990 4060
Lot No.
3.2.109
4.109
4.8.109
5.6.109
6.4.109
7.2.109
8.109
elec
tron
dens
ity [1
/cm
3 ]
5.106
107
1.5.107
2.107
2.5.107
3.107
3.5.107
colls
ion
rate
[1/s]
optic
al em
issio
n (E
P) *
3000
40
60
80
100
120
140
etch
tim
e [s] quick cleanquick clean
Cl2-MFC drift/errorCl2-MFC drift/error
Cl2-MFC errorCl2-MFC error
main cleanmain clean
Al etching - trend analysis main etch
Workshop on Self Excited Electron Plasma Resonance Spectroscopy8. - 9. June 1999 at Infineon Technologies Dresden - 15 - P. Höhmann
Infineon Regensburg
Plasma diagnostic at LAM TCP 9600SETM
one lot one point
Trend analysis of amemory productcovering 77 lots.
Shows the effect of thequick clean on thecollision rate.
The collision rate isthe most sensitiveparameter, in particularforecasting MFC error.3640 3710 3780 3850 3920 3990 4060
Lot No.
3.2.109
4.109
4.8.109
5.6.109
6.4.109
7.2.109
8.109
elec
tron
dens
ity [1
/cm
3 ]
6.106
9.106
1.2.107
1.5.107
1.8.107
2.1.107
2.4.107
colls
ion
rate
[1/s]
optic
al e
miss
ion
(EP)
*50
0
0
10
20
30
40
etch
tim
e [s
]
Quick cleanQuick clean
Cl2-MFC drift/error Cl2-MFC drift/error Cl2-MFC errorCl2-MFC error
main cleanmain clean
Al etching - trend analysis barrier etch
Workshop on Self Excited Electron Plasma Resonance Spectroscopy8. - 9. June 1999 at Infineon Technologies Dresden - 16 - P. Höhmann
Infineon Regensburg
Plasma diagnostic at LAM TCP 9600SETM
main etch (Al) and barrier etch (TiN, Ti)
One point represents one lot - stepwise analysis.
Shows the differentdependence of processsteps on events,e.g., cleaning procedures.
3640 3710 3780 3850 3920 3990 4060Lot No.
5.106
107
1.5.107
2.107
2.5.107
3.107
colli
sion
rate
[1/s]
main etch stepmain etch step
Cl2-MFC errorCl2-MFC error
main cleanmain clean
barrier etch stepbarrier etch step
quick cleanquick clean
Al etching - trend analysis collision rate
Workshop on Self Excited Electron Plasma Resonance Spectroscopy8. - 9. June 1999 at Infineon Technologies Dresden - 17 - P. Höhmann
Infineon Regensburg
Plasma diagnostic at LAM TCP 9600SETM
K ey item s R esu lts
M onito r / contro l power coup ling in to the p lasm a? Y es
Too l m atch ing? Y es
Long term too l stab ility? Y es
D evelop ing / optim izing processes? Y es
C ontro lling cham ber c lean ing procedures? Y es
R eduction of test- and m onitor wafers? Y es
Layer reso lu tion? Y esdem onstra ted fo rTi,
S iO 2, A R C and photo res is t
S patia l reso lution? N o
D etection of too l fa ilu re? Y es(e .g . C l2-M FC fa ilu re)
Summary
Workshop on Self Excited Electron Plasma Resonance Spectroscopy8. - 9. June 1999 at Infineon Technologies Dresden - 18 - P. Höhmann
Infineon Regensburg
Plasma diagnostic at LAM TCP 9600SETM
increasing - overall equipment effectiveness- reliability and uptime- statistical analysis- MTBF- yield- throughput
decreasing - cost of ownership (equipment)- MTBR- time for equipment base lining- time for process development
TM
®Benefit from outfitting LAM TCP with
HERCULES /PL