Technique for preventing stiction and notching effect on silicon-on-insulator microstructure

The notching (undercutting or footing) and stiction problem, which widely exists in silicon-on-insulator microstructure were resolved in this study regardless of the feature sizes, by the introduction of a spacer oxide thin film. In this modified process, the deep reactive ion etching was divided into several steps, where conformal plasma enhanced chemical vapor deposition oxide coating, and anisotropic oxide etch were employed to prevent the notching effect. Dry chemical release was also realized in this approach but the deep etching did not etch through the device layer. The notching or footing effect was exploited for attaining the lateral etching following the deployment of the anisotropic plasma etching of the inductively coupled plasma. This method was proven useful for both the uniform and nonuniform feature designs. To validate the proposed etching method, an optical switch was fabricated. The details and benefits of the proposed process and its extensions to more valuable and flexible design were all discussed in this article.