A Study On The Optical Alignment Of The Laser Projection Lithography Machine

The alignment technology is one of the most important technologies in lithography. In a way, the alignment precision and speed almost decides the quality and productivity of the lithography system. Therefore, research and exploration into a high precision and high speed optical alignment system is particularly important.By testing the existing laser projection photolithography system, we got the best exposure conditions:the edge of the developed PCB substrate is still clear until its line width reach at15μm; through the laser projection lens system, at the distance of8cm from the laser positioning table to the optical alignment system, the laser repeat frequency at15Hz, substrates exposure time at20s, development time at60s and developing temperature at30degrees Celsius, substrates can reach the best exposure condition.On basis of this existing lithography system, we designed an optical alignment system. It can realize alignment from three dimensions and it’s align precision can reach to2μm. Its shining point is that the system can complete adjustment with the law of the focal depth, which can make this method of autofocus faster.Combined with the existing laser projection lithography system, by using photometric optical alignment system and video monitoring scheme, plus the pure phase filter using to improve the autofocus arithmetic in the existing optical system, we put forward a set of control system to control and drive the optical alignment system. And this optical alignment system based on the control system can improve the speed and precision of optical alignment system effectively.