0.15 μm GaN MMIC PA Based on Advanced i-line Lithography Process

The resolution enhancement lithography assisted by chemical shrink (RELACS) is presented to increase the resolution of the i-line lithography. We have succeeded in developing an advanced i-line lithography process based on i-line stepper lithography and second-RELACS process. Moreover, the limit resolution of i-line lithography can be increased from 0.35 μm to 0.1 μm at the first time, and the wafer yield of GaN high electron mobility transistor (HEMT) with 3.1 mm gate width which has an L_g = 0.147 μm is 87.4 %. Besides, the second-RELACS process is applied to X-band GaN monolithic microwave integrated circuit power amplifier (MMIC PA), the resist width and gate length are about 0.15 μm and 0.2 μm. It is confirmed that the wafer yield of T gate with 6.8 mm gate width can be as high as 70.2 %. Comparing with the results of deep ultra-violet (DUV) lithography, the electrical and radio frequency (RF) characteristics of the GaN HEMTs fabricated with the second-RELACS process are stable.