Wafer Manufacturing

9Grinding, Edge Grinding, Etching, and Surface Cleaning

9.1 Introduction

In this chapter, several processes of wafer manufacturing are presented. These processes include wafer grinding and edge grinding (or edge rounding) in wafer forming, etching in wafer polishing, and wafer surface cleaning in wafer preparation, as illustrated in Figure 2.1. The grinding process of wafer surface processing is in Section 9.2. The edge grinding process of wafers is presented in Section 9.3. Various topics of etching and cleaning of wafers are presented in Sections 9.4–9.6.

9.2 Wafer Grinding for Surface Processing

As illustrated in Figure 7.6, the wafer grinding process can complement lapping for wafer surface processing, especially for large wafers such as 300 mm silicon wafers. Wafer grinding technique can be broken into rough grinding and fine grinding in wafer surface process. A rough grinding/preliminary planarization can be performed on wafers before they are batched for lapping to reach the required flatness and to remove waviness. (see also discussions in Sections 7.4.2 and 7.5.1).

Because silicon material is fragile and brittle after shaping into a wafer, one of the main challenges of wafer grinding is meeting the required high capacity to obtain economical yields, and be able to compete with the current batch lapping technology. In addition, the finished wafer product must have precise thickness in the range of microns that is suitable for micro‐fabrication applications. In the ...