Improvement of critical dimension stability of chemically amplified resist by overcoat

Abstract

The critical dimensions (CD) change by the process delay is the most critical issue to use the chemically amplified resists (CAR) for photomask fabrication. In the photo-mask fabrication processes, the resist should have both post coating delay (PCD) and post exposure delay (PED) stability, while keeping higher sensitivity. To achieve this requirement, overcoat process has been examined for the purpose of CD stabilization in CAR process for photomask manufacture. The material, which consists of hydrophobic polymer and photo acid generator (PAG), was used for the overcoat in this study. It has been proved that the overcoat shows the effect of controlling CD change, and applying the overcoat does not generate a fatal number of defects and pinholes. From these results, it is thought that the overcoat process is promising for the size stabilization in photomask manufacture for 100 nm devices.