22 September 1995 Process-induced damage to SRAM poly-load resistance during photoresist ashing in H2O plasma
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Process-induced damage to SRAM poly-load resistance have been clearly observed during photoresist ashing in an H2O plasma which is commonly acknowledged as an effective corrosion-prevented treatment after metal etching in a chlorine-rich environment. The resistance degraded to about three order in the H2O plasma than in the conventional O2 plasma. Different ratios of H2O to O2 plasma have been studied by using the well-designed pattern to understand the basic mechanisms of the problems which occurred in the photoresist ashing process. Experimental results showed that the higher concentration of H2O, the more damage to the SRAM products, resulting in the lower resistance of poly-load. Hydrogen ions generated from H2O plasma are speculated to be the major culprit. Different types of plasma sources (microwave and inductively coupled plasmas) for H2O-plasma photoresist ashing process have also been investigated and found that the damage effects to SRAM poly-load resistance in the inductive-type plasma source (such as Transformer Coupled Plasma) is more severe than that in the microwave-type plasma at the similar operation conditions. This may because inductive-type plasma has higher degree of ionization which generated more hydrogen ions inside the H2O plasma.
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Kuang-Hui Chang, Kuang-Hui Chang, Y. C. Huang, Y. C. Huang, Ting-Huang Lin, Ting-Huang Lin, Chaur-Rong Chang, Chaur-Rong Chang, } "Process-induced damage to SRAM poly-load resistance during photoresist ashing in H2O plasma", Proc. SPIE 2635, Microelectronic Manufacturing Yield, Reliability, and Failure Analysis, (22 September 1995); doi: 10.1117/12.221457; https://doi.org/10.1117/12.221457


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