Standing-wave effect in photoresist with and without HMDS

We evaluated standing-wave effects in photoresists with and without hexamethyldisilazane (HMDS), which improves adhesion of a photoresist to a Si-wafer substrate, using a resist development analyzer (RDA). The amplitude of a swing curve with HMDS was reduced around 9% compared to that without HMDS. Perhaps, this is considered a reduction of standing-wave effect in the photoresist attributable to an antireflection effect of an HMDS-photoresist mixed layer. The antireflection effect of the layer was evaluated by calculation using PROLITH. We demonstrated that the thickness, a refractive index and an extinction coefficient of the layer were, respectively, 10 nm, 1.60 and 0.5. Using HMDS can expect to improve dimensional stability by 1.17 times on the calculations.