Investigating the Core Parameters to Fabricate V-Shaped Diffraction Grating via MA-P 1215 Positive Photoresist

Abstract

In this study, the core deposition parameters for the MA-P1215 positive photoresist, namely; spin-coating speed, baking temperature and exposure fluence, have been investigated and optimized using a mask aligner, thermogravimetric and a spectroscopic ellipsometry. The optical properties, specifically, the refractive index n and extinction coefficient k for the films have been calculated via changing the fluence of the energy. The reduction in the thickness of the films with the increase in the spin-coater speed reflects the low viscosity of the MA-P photoresist. The relation between the weight reduction of the film via baking temperature and time reveals that the optimized baking temperature is 120 °C for 2 min, in which the weight of the film is reduced by 51%. We found that the values of both n and k depend on the exposure fluence. At small fluence values, both n and k decreased linearly with the increase in the wavelength. However, by increasing the fluence, the values of n and k became like those for silicon wafer, revealing that the developed film was totally removed. The contrast curve shows a decrease in the film thickness when the fluence of the exposure is increased, and the optimized fluence is found to be 35 mJ/cm2.