Chen Wangfu, Yan Wei, Hu Song, Yang Yong, Zhou Shaolin
State Key Laboratory of Optical Technologies for Microfabrication, Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209, China.
Appl Opt. 2010 Feb 1;49(4):708-13. doi: 10.1364/AO.49.000708.
Since accurate alignment is essential for projection lithography, an extended dual-grating based alignment scheme is proposed. This method is an extension of the basic dual-grating alignment model, the mechanism of which is explained to make it clear how the extended scheme performs in projection lithography. The framework of the extended alignment scheme for projection lithography is constructed, and the process of key parameter determination is then detailed. In both cases, a tiny shift of the wafer during the alignment process can be resolved by a conspicuous displacement or phase variation of corresponding fringes. Analytical results indicate that alignment is independent of the gap between wafer and mask, disturbance from the fluctuation in illumination can be neglected, and alignment resolution in subnanometers can be realized with this scheme.
由于精确对准对于投影光刻至关重要，因此提出了一种基于扩展双光栅的对准方案。该方法是基本双光栅对准模型的扩展，对其机理进行了解释，以明确扩展方案在投影光刻中的工作方式。构建了投影光刻扩展对准方案的框架，然后详细说明了关键参数的确定过程。在这两种情况下，对准过程中晶圆的微小偏移都可以通过相应条纹的明显位移或相位变化来解决。分析结果表明，对准与晶圆和掩模之间的间隙无关，可以忽略光照波动的干扰，并且该方案可以实现亚纳米级的对准分辨率。
