Modeling and Mapping of Nanotopography Interactions with CMP D. Boning and B. Lee, MIT W. Baylies, BayTech Group N. Poduje, ADE Corp. J. Valley, ADE Phase-Shift MRS Spring Meeting Symposium on Chemical Mechanical Planarization April 2002. Outline. Review: Nanotopography interaction with CMP
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Modeling and Mapping of Nanotopography Interactions with CMPD. Boning and B. Lee, MIT W. Baylies, BayTech GroupN. Poduje, ADE Corp.J. Valley, ADE Phase-ShiftMRS Spring MeetingSymposium on Chemical Mechanical PlanarizationApril 2002
MIT/Nanotopography CMP Models
Å
Å
MIT/Nanotopography CMP Models
Initial oxide surface after conformal deposition
Oxide Thickness Deviation
Final oxide surface, assuming uniform CMP removal
CMP
Actual Final Surface, after CMP removal
Remaining Oxide
mm distances
Silicon with initial nanotopography feature
MIT/Nanotopography CMP Models
CMP
Inverted oxide thickness
with zero mean
Nanotopography
filtered wafer height map
Å
Single-Sided Polish Wafer Data @ 20mm EE
MIT/Nanotopography CMP Models
PhysicalSimulation
Filtering
Scaling
Simple
Complex
Inital Wafer Nanotopography Heights (NH)
CMP Transfer Function
Final post-CMP Oxide Thickness Deviation (OTD)
MIT/Nanotopography CMP Models
After Schmolke et al., JECS, 2002
MIT/Nanotopography CMP Models
MIT/Nanotopography CMP Models
Chekina, JECS 1998;Yoshida, Proc. ECS, 1999
MIT/Nanotopography CMP Models
MIT/Nanotopography CMP Models
Å
DSP1
SSP1
SSP2
SSP3
MIT/Nanotopography CMP Models
MIT/Nanotopography CMP Models
MIT/Nanotopography CMP Models
MIT/Nanotopography CMP Models
MIT/Nanotopography CMP Models
MIT/Nanotopography CMP Models
PL = 3.4 mm
PL = 6.4 mm
PL = 9.7 mm
S - scaling
F - filter
CW - contact wear
MIT/Nanotopography CMP Models
ContactWear
Filtering
Scaling
Simple
Complex
Inital Wafer Nanotopography Heights (NH)
Final post-CMP Oxide Thickness Deviation (OTD)
CMP Transfer Function
MIT/Nanotopography CMP Models
MIT/Nanotopography CMP Models
CMP
oxide (300 nm)
nitride (100 nm)
pad ox (10 nm)
silicon
STI stack over nanotopography: post-CMP
STI stack over nanotopography: pre-CMP
MIT/Nanotopography CMP Models
Initial clearing or “Endpoint” is detected when top points begin to clear
Failure to Clear Oxide
oxide
nitride
silicon
STI stack: pre-CMP
Post-CMP with too little overpolish
MIT/Nanotopography CMP Models
Note visual correlation with initial nanotopography “low spots”
Initial Nanotopography
3% of wafer does not clear
Å
Blue indicates uncleared areas
Initial Nanotopography
MIT/Nanotopography CMP Models
NitrideThinning
Remaining nitride
oxide
nitride
silicon
STI stack: pre-CMP
STI stack: post-CMP
MIT/Nanotopography CMP Models
InitialNanotopography
TotalRemoved
Zoom on TotalRemoved
MIT/Nanotopography CMP Models
Initial Nanotopography
Nitride Thinning
Å
Å
E= 147 MPa
MIT/Nanotopography CMP Models
Note visual correlation with nanotopography “high spots”
Initial Nanotopography
Potential Failure Locations
Å
4.5% Area Failure
Initial Nanotopography
Red indicates excessive nitride thinning– greater than 20 nm budget (20% of 100 nm)
E= 147 MPa
MIT/Nanotopography CMP Models
MIT/Nanotopography CMP Models