Study On The Fabrication And Simulation Of Nano-gratings With Phase Mask Lithography

The technology of micro-electronics and micro-processing has achieved rapid development from the 1960s.The lithography technology is one of the most sophisticated technologies in semi-conductor processing technology.This paper mainly introduces the fabrication and simulation of nano-gratings with phase mask lithography,including the following parts.The first part is the introduction,which includes a brief introduction of the background and the significance of the lithography process,and the theory and processing of the nano-imprint lithography.The second part is a fundamental introduction of the theory analysis of the phase mask lithography. It points out that fabricating Bragg Gratings having a periodicity of A/2 with the phase mask with a periodicity of A by phase mask lithography is accomplished by the interference of the two ±1st diffracted order beams and the suppression of the 0th order beams. And in this part,we also demonstrate two methods to change the duty cycle of the gratings.Next part is results and discussion of experiment. We fabricate Bragg Gratings having a periodicity of A/2 with the phase mask with a periodicity of A by phase mask lithography.In this part,we analyze the reason why we can not get the nano-gratings in large area.It is mainly due to that it is difficult to fit the mask and substrate perfectly in nanometer scale and fix the mask in the position where the incident light can incident vertically manually.The fourth part is the simulation.We simulate the interference patterns produced by the phase mask with different periods and depth of the phase mask by the software named comsol.At first,we fix the period of the mask to find its best depth.And then we change the periods and to find the best depth in different periods.At last,we fix the depth of the mask,and change the periods of the mask in three ranges:A<λ、Λ～λ and λ<Λ<2λ.We find that,at the best depth,the optical field behind the mask is the best when the period is near 1.5λ,and when the period is getting closer to λ, and 2λ,the optical field becomes worse,and sometimes we can even not get the optical field whose period is half of the mask.lt may because that when the period is near 1.5λ,the ±1st diffraction light is strong and when the period is near λ and 2λ,the 0 and ±2nd diffraction light is strong and now the ±1st diffraction light is weak relatively.At last, the conclusion is made.