Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.
Nano Lett. 2013 Aug 14;13(8):3716-21. doi: 10.1021/nl401622b. Epub 2013 Aug 6.
Due to the diffraction limited resolution and the presence of speckle noise, visible laser light is generally thought to be impractical for finding deep subwavelength defects in patterned semiconductor wafers. Here, we report on a nondestructive low-noise interferometric imaging method capable of detecting nanoscale defects within a wide field of view using visible light. The method uses a common-path laser interferometer and a combination of digital image processing techniques to produce 70 μm by 27 μm panoramic phase and amplitude images of the test nanopattern. Significant noise reduction and high sensitivity are achieved, which enables successful detection of several different types of sparse defects with sizes on the order of 20 nm wide by 100 nm long by 110 nm tall.
由于衍射极限分辨率和散斑噪声的存在，可见光通常被认为不适用于在图案化半导体晶圆中寻找深亚波长缺陷。在这里，我们报告了一种无损低噪声干涉成像方法，该方法使用可见光在宽视场中检测纳米级缺陷。该方法使用共光路激光干涉仪和数字图像处理技术的组合，生成测试纳米图案的 70μm×27μm 全景相位和幅度图像。实现了显著的噪声降低和高灵敏度，成功检测到几种不同类型的稀疏缺陷，其尺寸约为 20nm 宽、100nm 长和 110nm 高。
