Research On Laser Lithography System On Non-planar Surfaces And Key Technologies

Microlithography on non-planar surfaces is a development direction of micro-element fabrication now, and laser lithography on non-planar surfaces is an important development direction of the fabrication of micro-elements, particularly micro-optics, on non-planar surfaces. Compared with on planar surfaces, laser lithography on non-planar surfaces faces more difficulties due to the introduction of the variable tilt angles of non-planar substrates. Now, the technologies, processes, and equipments relating to laser lithography on non-planar surfaces are still in primary stages.A novel laser lithography system on non-planar surfaces is constructed in this dissertation. This system can realize the detection and control of optical focus and exposure on non-planar substrates with the innovative constant posture configuration of lithography head. In addition, the theory of exposure on non-planar surfaces, the detection of optical focus on non-planar surfaces, and the control of optical focus on non-planar surfaces are respectively researched in this dissertation.The transmission and exposure of the light field in the photoresist layer on non-planar surfaces, and the influences of process parameters on micro-structure lines in the case of on non-planar surfaces and so on, are researched in the dissertation. Firstly, the dissertation constructs the transmission and distribution models of the light field in the photoresist layer on non-planar surfaces. Secondly, the dissertation analyses various scan-exposure modes for non-planar surfaces, and constructs the Dill exposure model for non-planar surfaces, and the exposure models of the photoresist layer for various scan-exposure modes. On the basis of these, the dissertation constructs the line-width models for non-planar surfaces for various scan-exposure modes, analyses the influences of various process parameters on lines in the case of various scan-exposure modes.The detection and control of optical focus on non-planar surfaces is the key to the laser lithography system on non-planar surfaces. On the basis of confocal microscopy technology, a response model of optical focus on non-planar surfaces is constructed in the dissertation. Based on this model, the dissertation obtains the response properties of optical focus on non-planar surfaces, and then presents a novel approach for the detection of optical focus on non-planar surfaces, that is so-called dynamic scan detection method. The principle and parameters of this method are analysed and researched in the dissertation. Based on this method, the dissertation constructs a focus error signal (FES) reflecting the position of optical focus on non-planar surfaces.For the control of optical focus on non-planar surfaces, a macro/micro dual-drive control system is applied in the dissertation, according to the properties of lithography on non-planar surfaces. Because of the particularities in laser lithography, some special designs are made for the macro/micro dual-drive control system, including FES signal construction, synchronous configuration and so on. In addition, two focus-searching mechanisms for non-planar surfaces are presented in the dissertation, which are respectively applied to searching for focus during the initialization of the laser lithography system, and during the exposure in the case of losing focus or out-of-control of the closed loop.On the basis of the laser lithography system constructed in the dissertation, some preliminary experiments are conducted, and a circular grating and a linear grating are also produced on non-planar substrates.