Bevel Etch

Bevel Etch

Material Name: Silicon
Record No.: 100
Primary Chemical Element in Material: Si
Sample Type: Wafer
Uses: Etching
Etchant Name: None
Etching Method: Dry etching
Etchant (Electrolyte) Composition: No data
Procedure (Condition): No data
Note: Cross-contamination via etch or deposition due to plasma attack or thermal stress-induced delamination cannot be ruled out even if a single wafer cleaning tool is used. If waferedge exclusion is already optimized, other means such as bevel polish or bevel etch are needed to overcome cross - contamination issues. The production process of 90 nm and 80 nm DRAM products in this study showed needle-shaped defects, which turned out to be poly-silicon residues from the bevel area as shown in Figure 1. Such residues could be successfully removed by bevel dry etch – which has not been benchmarked with bevel polish in the present case, bevel wet etch, bevel plasma etch, and bevel brush clean tools which are also available commercially.
Reference: Oguz Yavas, Ernst Richter, Christian Kluthe & Markus Sickmoeller, Wafer-edge yield engineering in leading-edge DRAM manufacturing, Semiconductor Fabtech -39th Edition, www.fabtech.org, 2009, pp. 1-5.

Figure 1: SEM images of poly-silicon residues at wafer bevel removed by bevel dry etch (top), and resulting defect improvement in the wafer edge region (bottom).