基于分步式压印光刻的激光干涉仪纳米级测量及误差研究

Research of Measurement and Measuring Error of Laser Interferometer in Step Imprint Lithography

针对在未做隔离保护处理的环境中,基于Michelson干涉原理的激光干涉仪测量系统存在严重的干扰误差,不适合分步式压印光刻纳米级对准测量的要求.采用Edlen公式的分析及计算,不仅在理论上揭示出环境温度、湿度、气压等变化对激光干涉仪测量准确度的影响,而且证明影响测量准确度的最大干扰源是空气流动的结果.通过气流隔离措施和系统测量反馈校正控制器,能够实时补偿激光干涉仪两路信号的相差.最终,测量漂移误差在10min内由13nm降低到5nm以内,满足压印光刻在100mm行程中达到20nm定位准确度要求.

To the nano-position measurement of imprint lithography process, when the Michelson interference theory is used in laser interferometer measuring system in common environment conditions, it is difficult to avoid the disturbing error, which is fatal to measuring result. Through analyzing and calculating the Edlen formula, not only the influence from changes of temperature, humidity, and atmospheric pressure in measuring environment to laser interferometer measurement accuracy is theoretically revealed, but also the most serious disturbance coming from the flowing air is proved. By adopting the isolating mask of air flow and compensating feedback controller in measuring system, the phase-shift error between two laser interference signals can be compensated in real-time. At last, the measuring drifting error can be reduced from 13 nm to 5 nm in 10 minutes and this optimized measuring system can be used in the imprint lithography and match to the needs of 20 nm positioning accuracy in 100 mm motion range.