用白光干涉测量法描述化学机械抛光面

Characterization of Chemical MechanicalPlanarization With White Light in Interferometry

化学机械抛光(CMP)在半导体工业内获得了广泛的赞同,对控制形貌起伏的硅片表面当作首选方法。一种可供选择的基于白光测量原理之上的非接触光学形貌测量法被推出。和大多数商业化只能以纳米精度测量不透明表面的白光干涉测量仪不同,新推出的方法是通过单频相位干涉测量仪(PMI)能够以相似的精度测量透明的可变化反射像的表面结构,这个可变化的反射相也许是由于单层或多层薄膜堆叠在一个底层上的多层表面材料特性所引起的,或者是硅片上其它微结构所引起的。因而,在化学机械抛光加工处理过程中的某些不合格项,例如,碟形腐蚀,可以直接用光学形貌测量法在几秒内做出定量的检测结果。此外,这一方法也能评价附加的,例如特种专用薄膜堆叠层厚的表面特性。由于高精度和高生产能力的结合特征使得这一被提议的方法可能确定为可行的化学机械抛光加工研发和生产的监测方法。

Chemical mechanical planarization （CMP） has gained wide acceptance within the semiconductor industry as the preferred method for controlling wafer topography. An alternative non-contact optical topographical method based on the principles of white light interferometry （WLI） is presented here. Unlike most commercial WHI instruments that are capable only of measuring opaque surfaces with nanometer precision, the proposed method is able to measure non-opaque structured similar to that obtained by monochromatic phased-measuring interferometry （PMI）. The phase shift on reflection may be due to the material properties of bulk surfaces, single or multi-layer film stacks on a substrate, or other micro-structures on the wafer. As a consequence certain undesirable CMP process artifacts, such as dishing and erosion, can be quantified from the direct optical topographical measurement within sec- onds. Furthermore, this method is able to estimate additional surface properties such as the layer thicknesses of specified film stacks. By combining the attributes of high precision and high throughput, the proposed method may establish the feasibility of CMP process development and production monitoring.