基于刻线工艺参数的光栅尺曝光拼接动态补偿及精度评价方法优化研究

The off-line measurement compensation technology for exposure stitching scribing of linear scale is difficult to solve accuracy consistency of batch manufacturing accuracy of less than ±1μm/m, and which cannot be solved by contact-type replication method with process constraints. This project aims at the problem of ruling accuracy for linear scale and high-precision accuracy consistency control of mass production. Error analysis, optimization algorithms, and simulation analysis methods are used to study on dynamic compensation and accuracy evaluation method for exposure stitching of linear scale based on ruling process parameters. According to the comprehensive expression model of the global parameters of the exposure stitching, an adaptive exposure stitching method that satisfies the efficiency and precision of the grating ruler line is established. Through study on pitch value shift and pitch pose accuracy of exposure stitching to reveal the formation rules on errors of joints, pitches, and accumulation of exposure stitching mode under complicated process parameters. The mechanism of the coupling effect of the error source chain mapping parameters on the splicing pitch is studied, and the precision prediction model and dynamic compensation method suitable for high-precision meter-scale grating splicing are established. The characteristics of grating stripe shape and position error evaluation are studied. The evaluation method of grating pitch error and cumulative error is proposed. The dynamic error compensation parameter and precision distribution interconnection relationship are established, which provides theoretical basis for grating ruler dynamic error compensation technology and evaluation method.

直线光栅尺曝光拼接刻划采用离线测量补偿技术难解决精度小于±1μm/m范围内的批量制造精度一致性，而接触式复制方法受工艺制约也不能解决该问题；本项目针对直线光栅尺刻划精度及批量制造精度一致性控制问题，采用误差分析、优化算法和仿真分析的方法，研究基于刻线工艺参数的光栅尺曝光拼接刻划动态误差补偿及精度评价方法优化；根据曝光拼接全局参数的综合表达模型，建立满足光栅尺刻线效率及精度的自适应曝光拼接方法，通过光栅尺曝光拼接间距量值偏移及间距位姿准确性研究，揭示曝光拼接模式在复杂工艺参数下接缝、栅距、累积等误差形成规律；研究误差源链映射关系参数对拼接间距的耦合影响机理，建立适应于高精度米级光栅尺曝光拼接的精度预测模型和动态补偿方法；研究光栅条纹形状特征及位置误差评价规律，提出光栅尺栅距误差及累计误差的评价方法，建立动态误差补偿参数与精度分布互联关系，为光栅尺刻划动态误差补偿技术及评价方法提供理论基础。

目前，我国光栅尺研发投入主要采用跟踪国际水平战略，不仅严重滞后，且由于缺乏对相关光栅尺刻划的基础性科学问题和应用技术的研究，导致刻划光栅在企业应用效果不佳。本项目系统地研究了多步重复刻线及栅距误差评定的相关问题，包括直接拼接光刻误差、多步投影重复光刻对接误差及其均化效应、光刻物镜畸变相关参数比对投影刻线栅距精度的影响、曝光源恒速运动曝光模式或运动-静止定位曝光模式动态刻线误差分析，建立了曝光间隔距离误差数学模型、曝光重复次数数学模型、掩膜版误差数学模型，采用仿真分析方法，研究了整数及非整数倍间隔误差对光栅黑白条纹精度的影响规律，掩膜板误差、重复曝光次数、间隔距离误差、焦平面对准误差等拼接全局参数对刻线精度及效率的影响规律及工艺参数范围；提出了计算光刻阈值模型，建立了整根光栅尺产生误差的数学模型，包含光刻工艺参数栅距、光栅条纹个数、刻划光栅长度、光刻阈值、光栅尺线膨胀系数、温度等参数，形成影响光刻拼接误差的链路；提出了一种投射光栅尺焦平面对准的方法，对间距位姿、直线度误差与焦平面动态调整参数补偿关系等进行了研究和验证；栅距误差评定采用最小区域法及读数信号细分法，对光栅条纹形状、均匀性及边缘特征等进行了研究；在提升光栅尺刻划精度和提升批量制造精度一致性方面，研究了整根光栅尺平面度参数及焦距控制范围、多步重复光栅条纹个数及曝光能量时间控制等参数离线动态补偿，采用焦平面动态补偿方法、多步重复栅距动态补偿方法进行了计算仿真等研究工作。研究结果表明，本项目的光刻工艺多参数动态补偿方法比较适合多步重复刻线方法在精度上的控制需求，能够实现精度＜±1μm/m。同时刻线动态补偿误差技术在其他领域如大尺寸平面衍射光栅拼接、液晶面板、二维光栅尺、集成电路晶圆等刻线工艺具有借鉴意义。