A New Two‐Level Resist Patterning Process Based on Resist Volatilization under Deep UV Exposure

A new two‐level resist patterning process is proposed. This process is based on the fact that, under deep‐UV exposure, polymethacrylate resist (such as FPM) can be etched by way of volatilization, and the etching rate is faster than that of novolak‐type resist (such as AZ). The two‐level structure consists of FPM as a bottom resist and AZ as a top resist. After delineating the top resist, the bottom resist is patterned using the AZ resist as a mask. This procedure provides a very simple technique for controlling the resist profile for use in lift‐off process.