Study On Automatic Alignment Technology In Proximity Contact Lithography System

In the manufacturing process of semiconductor chips,the lithography machine is the most critical equipment.As one of the most technically complex equipment,the lithography machine integrates the most sophisticated optical,mechanical,electrical and computing technologies into one.As one of the three core technologies of lithography,alignment technology plays a vital role in lithography production.Improving the accuracy of photolithography alignment can directly increase the accuracy of overprinting,thereby improving product quality,and at the same time,increasing the speed and efficiency of photolithography alignment can also increase product productivity.Proximity-contact lithography system,as one of the important equipment in chip manufacturing,puts forward higher requirements on lithography alignment technology.At present,the proximity-contact lithography system mainly relies on specific alignment marks for video image alignment.However,there are more and more types of alignment marks,part of the photolithography process no longer designs special alignment marks,but directly uses photolithography patterns or silicon wafer outlines as alignment marks for alignment.Based on the research status of lithography alignment technology,combined with the requirement of proximity contact lithography for alignment based on photolithography patterns or silicon wafer contours,this paper proposes a video image alignment algorithm based on arbitrary pattern alignment.Based on the simulation of the alignment algorithm,experiments were further carried out on the proximity-contact lithography system to verify the feasibility of the alignment algorithm.The repeatability can reach sub-micron and meet the requirements of alignment accuracy.A series of experiments with different alignment marks have verified the feasibility of the alignment algorithm applied to arbitrary graphics.