Conformal coating of poly-glycidyl methacrylate as lithographic polymer via initiated chemical vapor deposition

Abstract

This study reports on the investigation of the potential applicability of poly-glycidyl methacrylate (PGMA) films deposited via initiated chemical vapor deposition (i-CVD) as lithographic resists in the microfabrication of non-planar structures. We investigate the appropriate deposition conditions of i-CVD required to form PGMA films with smooth surfaces. As a result, under the optimal conditions determined by us, we fabricate films with nanometer-scale flat surfaces. Subsequently, we demonstrate that i-CVD is effective for conformally coating a high-aspect-ratio Si trench with PGMA film via our deposition experiments. In our deep-ultraviolet lithography experiment, we successfully fabricate a fine 20-μm line-and-space (L/S) pattern with a height of approximately 1 μm. Furthermore, in our electron-beam (EB) lithography experiment, we define a fine 350-nm L/S pattern with a height of 120 nm. In addition, the i-CVD process can be used to form highly-sensitive EB resist films; the lowest dose amount for patterning these films is evaluated to be less than 0.01 μC/cm2. Our results demonstrate that i-CVD is a potentially powerful method to conformally coat lithographic resist films on three-dimensional structures.