Research On DMD-based Digital Photolithography

Photolithography is one of the core techniques in the manufacture of the semiconductor devices. It has gone from close to/contact photolithography, to projection photolithography, to stepper photolithography and then to the scanning photolithography. However, it is still a big trouble for researchers that decreasing the cost for fabricating the optical mask. In recent years, maskless photolithography has been developed rapidly, especially the DMD based photolithography has been the highlight in the field microfabrication. Since DMD has several advantages including flexible structure, parallel and high speed data processing, it could not only decrease the expense, but also solve the difficulties in the fabr ication of optical mask. Also, it could simplify the tedious process in the traditional semiconductor manufacture. Moreover, it has been an important role in the miniaturization, high-precision photolithography system. The DMD-based photolithography system will be one of the significant instruments in the field of microfabrication of next generation.In this thesis, the research on the digital photolithography technique is based on self-building DMD-based photolithography system. What has been done in this article includes modeling of DMD diffraction and its application, analysis of the errors in the system and their correction method. These researches could be the guide for the experimental researches next step.The important researches are as follows.(1) The numerical modeling is established based on the Fourier analysis. Besides,by using the diffraction model of DMD, it has been done that the analysis of the effects on the diffraction efficiency resulting from the manufacture errors of DMD and the errors of the system.(2) A diffraction model is established in the optical ray-tracing software. It is used for the analysis of the exposure results. The analysis in the condition of the image defocusing provides a simple way to calibrate the direction of defocusing.(3) It is analyzed that the effect of the inhomogeneity of the illumination on the exposure pattern. Besides, a correction method is proposed under the mode of scanning exposure. Also, it has been analyzed that the effects, which suffer from the errors in the system, on exposure pattern. They would influence the position of the exposure spot. According to the interrelationship among these errors, an integrated correction method is proposed.