Research On Maskless Lithography Technology And Exposure Method

Lithography is the core technology in integrated circuit manufacturing,whose etching linewidth is reducing driven by the semiconductor technology node,while the cost of mask and production cycle increase significantly,resulting in the complex production processes and high price of lithography.In recent years,some maskless lithography has been developed rapidly,and the lithography based on spatial light modulator(SLM)has been widely concerned in industry.Digital micromirror device(DMD)has the advantages of flexibility,high speed,high resolution and can be used as a SLM to generate the digital mask,which not only eliminates the mask and manufacturing equipment cost,but also improves the flexibility and efficiency of industrial production.This technology has wide application prospect in the field of micro-processing due to its advantages of low cost,high efficiency and simple structure.The thesis focuses on exposure imaging system in lithography,researches on the DMD imaging model,rapid exposure scheme and adaptive correction of errors,which has a guiding significance to the subsequent study of lithography equipment.The main research contents are as follows:1.Firstly,the selection of components and the design of the imaging system are studied.And a partially coherent imaging model is established according to the diffraction effect of DMD in the system.The model takes into account the microstructure of the DMD micro mirror,and focuses on the simulation of its diffraction imaging effect,and will be used for the analysis of the system imaging.2.In order to solve the problems of the traditional step scanning exposure in the large area lithography,such as the many mechanical error sources and the slow exposure speed,a high speed continuous scanning exposure scheme is presented.In this scheme,the line scanning and the inter row walking are used to refresh binary exposure images on the DMD.The imaging principle and exposure control of the proposed scheme are also studied and demonstrated in detail.The simulation results show that the scheme is feasible and the imaging surface is more smooth.3.In order to solve the problem of the stitching error in the process of continuous scanning exposure,a new method based on exposure control is proposed,which cuts exposure patterns according to the error of the grating feedback value.Then the exposure gradient distribution of stitching region is implemented by controlling the substrate unit during the scan exposure.The simulation results show that the proposed method can automatically adjust the exposure pattern according to the error feedback value and improve the quality of the image.4.In order to reduce the equipment cost and simplify the exposure process,a solution based on the video stream to transmit the exposure data is put forward in view of the shortage of the storage space of DLP6500 when the lithography system experiment platform is built.Combined with the solution,the proposed continuous scanning exposure program is verified by building the experimental platform and designing the host computer software.The results show that the exposure scheme can be used for actual production.