Polysilicon line damage and Burn-in effectiveness in a 0.18um mixed signal product
Polysilicon line damage and Burn-in effectiveness in a 0.18um mixed signal product
Thursday, October 31, 2024: 8:40 AM
204 (Hilton San Diego Bayfront)
Summary:
A 0.18um technology fabrication tool was observed to generate some damage on polysilicon lines (missing polysilicon lines). An increase in digital scan failure rate was observed. This was attributed to a particular fabrication cleaning tool. Improvement of the process was made. For all the material affected by the missing polysilicon line issue and to secure production, some additional production tests and burnin were introduced. Few devices were failing digital scan test post burnin, a very particular failure mechanism was observed. Physical failure analysis was performed on these devices, and it was related again to missing polysilicon located into the reset path of some Flip-Flops. Several improvements of the production test program were done to try to detect these devices pre-burnin. After a final review it was concluded that the reset path failure could only be detected after burnin.
A 0.18um technology fabrication tool was observed to generate some damage on polysilicon lines (missing polysilicon lines). An increase in digital scan failure rate was observed. This was attributed to a particular fabrication cleaning tool. Improvement of the process was made. For all the material affected by the missing polysilicon line issue and to secure production, some additional production tests and burnin were introduced. Few devices were failing digital scan test post burnin, a very particular failure mechanism was observed. Physical failure analysis was performed on these devices, and it was related again to missing polysilicon located into the reset path of some Flip-Flops. Several improvements of the production test program were done to try to detect these devices pre-burnin. After a final review it was concluded that the reset path failure could only be detected after burnin.