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End-Point Detection for CMP Using the AE Sensor
SFR Workshop & ReviewApril 17, 2002
Edward Hwang, David DornfeldBerkeley, CA
2002 GOAL: Integrate initial chemical models into basic CMP model. Validate predicted pattern development
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Motivation for End-Point Detection (EPD)
In-situ end-point detection of CMP offers many manufacturing advantages
• Improved Process Yields
• Reduced Product Variability
• Closer Conformance to Target Requirements
• Higher Throughput
But, difficult to implement due to the complicated nature of theCMP process
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Existing EPD Approaches
Thermal
ElectrochemicalOptical Motor Current
Motor Current
Microphone Optical
Friction
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Experimental Setup
COF
AESignal
Conditioning
Signal Conditioning
A/D (20KHz)
A/D (2MHz)
CETR Tool / DAQ System
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Experimental Setup
Cu(1,500Å)/Ta(250Å)/Oxide(5,000Å)Alumina based 5003 with 2.5% of H2O2
IC1000 Polyurethane
Oxide(2,000Å)/Nitride(1,000Å)DI Water(pH=11.5)
Fixed Abrasive
Copper CMP STI CMP
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AE Sensor – Major AE Sources
Tang et al, 1997
• Two or Three Body Abrasion
• Interaction Among the Abrasive Particles,Wafer, and Pad
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AE Data for Cu CMP
0 100 200 300 400 500 600 700 800 900 10000.0160
0.0165
0.0170
0.0175
0.0180
0.0185
Time(sec)
AE Signals(V)
Cu Ta Ox
EA B CD
A B C D E
Cu Ta Ox
487kg/mm2Oxide
112 kg/mm2Ta
115 kg/mm2Cu
Knoop Hardness
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AE Data / Friction Data for Cu CMP
A B C D ECu Ta Ox
0 100 200 300 400 500 600 700 800 9000.0160
0.0165
0.0170
0.0175
0.0180
0.0185
0.35
0.40
0.45
0.50
0.55
AE Signals(V) COF
Time(sec)
CuCu TaTa OxOx
A B C DE
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AE Data for STI CMP
Ox
Nitride
0 20 40 60 80 100 120 140 160 1800.006
0.008
0.010
0.012
0.014
0.016
0.018
Time(sec)
AE Signals(V)
A B
CD
Ox Nitride
A B C D
2100 kg/mm2Nitride
487 kg/mm2Oxide
Knoop Hardness
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AE Data / Friction Data for STI CMP
Ox Nitride
A B C D
0 20 40 60 80 100 120 140 160 1800.006
0.008
0.010
0.012
0.014
0.016
0.018
0.30
0.35
0.40
0.45
0.50
AE Signals(V) COF
Time(sec)
A B C D
OxOx NitrideNitride
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Current and Future Developments
• EPD motivations and challenges• Summary of Existing Approaches of EPD• AE RMS is proportional to Hardness• Possibility of using AE as an EPD method
• EPD on Patterned Wafers• Analytical Model for the Relationship Between AE Signals
and Hardness• Development of More Sophisticated Signal Processing System
for EPD of CMP
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2002 and 2003 Goals
• Integrate initial chemical models into basic CMP model. Validate predicted pattern development.
• Develop comprehensive chemical and mechanical model. Perform experimental and metrological validation
