Projection Lithography Zooming And DMD Maskless Lithography Imaging Research

Lithography process, depth of focus of the lithography objective lens is often only a few microns to tens of microns, it is not an easy task to find the focal plane, if the focal plane was not identified, the exposure quality was seriously affected. Thus, it is very important for the photolithography process to research reasonable zooming technology; in addition, with the photolithography pattern feature size getting smaller and smaller, the difficulty of mask production and fabricating cost was quickly increased, maskless technology based on DMD can effectively solve the above problems, expected to become the new darling of the future lithography, lithography projection objective lens is also one of the core components of maskless lithography system, but because of DMD own special structure, there is a big gap between lithography projection lens based on DMD and conventional lithography objective. Thus, it is necessary to study the lithography projection imaging system suitable for DMD. The main contents are as follows:To study the zooming for large-area laser projection lithography, first by using Zemax optical design software, the defocusing effect on modulation transfer function(MTF) and optical path difference(OPD) is simulated and the effect of OPD and MTF on the patterning quality of Projection Imaging Lithograpgy is analyzed, the system’s maximum defocusing range is also given. Then,a method of using microscope for zooming is proposed,analysed that the zooming errors of this method mainly come from the microscopical depth of field.According to the expression of the depth of field and the maximum defocusing value of this system,a microscope for constructing the zooming system whose depth of field is not more than the maximum defocusing amount is chosen.The experiment is demonstrated based on the zooming system for lithography.The results illustrate that the zooming by using this new method for Project Imaging Lithograpgy can obtain a good lithography patterns.Simply describing the structure of the DMD, the basic working principle,gray-scale quantization, highlighting the principle and optical structure of DMD dot-matrix lithography technology and the calculation method of fabricating integrated microlens array-spatial filter and DMD projection lithography and optical structure and the causes of emerging pixel structure and the method of removing pixel structure.Optimize a core component of DMD projection lithography,projection lithography objective lens. Select a double Gauss objective lens and Petzval objective lens as the the double telecentric projection lithography objective lens initiating structure,optimize a10times reduction projection lithography objective for TFT lithography.The optimization results were analysed from different angles by optical design software zemax comprehensive aberration within±2μm, wave front aberration within±0.1λ, maximum curvature of field less than2μm, the image plane illumination remains the same, the maximum distortion is less than0.005%, The maximum astigmatism1μm, the resolution Iμm.