IN-SITU MICRO STRAIN GAUGES FOR MEASURING RESIDUAL STRAIN OF THREE CMOS THIN FILMS USING ONLY ONE MASKLESS POST-PROCESSING STEP

Abstract

ABSTRACT The implementation of pointer-type micro strain gauges requires the use of standard CMOS process (Complementary Metal Oxide Semiconductor). To determine residual strain of thin films, micro strain gauges play a part in the process. By using an identical post-processing on the same chip, we are able to obtain three kinds of micro strain gauges of which their usage can measure residual strain of three distinct CMOS thin film materials. The mask-less post-processing requires only wet etching. Phosphoric acid is ideal to perform the etching of sacrificial layers. Finally test results of residual strains for CMOS thin films of silicone nitrate, silicon dioxide (compression), and aluminum (compression) are 1.6655×10−3, −2.6675×10−3 and -0.5105×10−3 respectively.