Automated Image Registration in the Semiconductor Industry: a Case Study in the Direct to Digital Holography Inspection System

摘要

Automated image, registration based on pattern recognition is a critical procedure in many applications of machine vision and is essential for accurate navigation and change detection. In this paper, an overview of the specific applications of image registration in wafer inspection is given, followed by a case study in the application of image registration fof direct to digital holography (DDH) wafer inspection. A complete system of novel algorithms for holographic image registration is then presented. In the case of DDH system with complex data flows, the proposed registration system is capable of accepting a variety of data streams as inputs: (1) complex frequency data; (2) complex spatial data; (3) magnitude data extracted from holograms; (4) phase data extracted from holograms; and (5) intensity-only data. This flexibility facilitates the development of faster, more reliable, and more efficient DDH processing systems, which is important in system optimization and production. In particular, the system enables the use of the full complex wavefront, which contains both reflectance and structural topology information, in the registration process. The added information contained in the wavefront can be utilized for increased robustness and computational efficiency. Both the theory and implementation of the proposed registration system are briefly described within the framework of DDH processing for wafer inspection tasks. Several examples of defect detection and wafer alignment are given with estimates of accuracy and robustness.