A 180nm lift-off process for 5GHz band surface acoustic wave filters using an i-line reduction stepper

Using an i-line reduction stepper, we successfully realized a lift-off resist pattern with a 180nm line and space (L/S) resolution. This pattern was achieved by combining the multilayer resist (MLR) process that we originally developed and optimum dipole off-axis illumination (OAI). The technology extends to resolution limit of i-line photolithography from 250nm to 180nm resolution. Using this technology, we fabricated 180nm L/S Al electrodes for a 5GHz band surface acoustic wave (SAW) filter. The characteristics of the filter were demonstrated.