Process Optimization of Integrated SiCr Thin-Film Resistor for High-Performance Analog Circuits

We investigated the characteristic variation of an integrated thin-film resistor (TFR), which is composed of silicon chromium (SiCr), according to process conditions and its effects on analog circuits. To improve TFR properties, such as temperature coefficient of resistance (TCR) and mismatch, the integrated TFR was examined under various process conditions. First, the sputtering power and the annealing temperature were optimized to control the TCR property. Secondly, the etching time and the dummy pattern were optimized to enhance the mismatch property. The measured TCR is -3.9 ppm/
^°
C and the calculated mismatch slope from the standard deviation of resistance mismatch is 0.34%·μm. These results show that the fabricated TFR had near-zero TCR and a high matching constant. To verify the TFRs effects on analog circuits, low-pass filters (LPFs) were fabricated and measured as a test vehicle; the use of the optimized resistor considerably improved the performance of the resulting LPFs.