Silicon Nitride Single-Layer X-Ray Mask

Abstract

In the low pressure chemical vapor deposition process, preparation of silicon nitride with low film stress and low refractive index is investigated as a function of deposition temperature and reactant gas ratio SiH 2 Cl 2 /NH 3 . The silicon nitride film with a stress of 15 kg/mm 2 and refractive index of 2.3 is formed at the deposition temperature of 850°C and the SiH 2 Cl 2 /NH 3 ratio of 4/1. Using the film as an X-ray mask, a silicon nitride single-layer X-ray mask is realized, which has a 30 ×30 mm window and has high transparency to visible light.