Damage Assessment Structure of Thermal-Annealing Post-Processing on CMOS LSIs

Abstract

We assessed the degradation of MOSFET and CMOS LSI circuit characteristics induced by the high temperature annealing, especially for the PZT deposition process. The test structure consists of ring oscillators having different numbers of stages and single PMOSFETs and NMOEFETs designed with $0.6 \mu \mathrm{m}$ CMOS technology. We observed the ring oscillator (RO) oscillating frequencies and the $I_{\mathrm{d}}-V_{\mathrm{g}}$ characteristics of the MOSFETs before and after the annealing post-process. The result indicated that such an annealing process involving high temperatures of around 575°C is possible unless the wiring on the CMOS components is mechanically broken. In addition, annealing temperature affected the MOSFET characteristics more than annealing times. Therefore, the effects of the CMOSMEMS monolithic integration using PZT thin films be optimized using the proposed test structures.