Handbook of Silicon Based MEMS Materials and Technologies

Chapter Thirty Eight. Encapsulation by Film Deposition

38.1. Introduction

Encapsulation by deposition of a thin film is an attractive alternative to wafer bonding due to the possibility of reduced thickness and area of a packaged device, as well as elimination of the need for a capping wafer. Surface micromachining advancements in the 1980s and 1990s enabled device and encapsulation layers each to be only tens of μm thick. By combining this with thinning of the wafer backside via chemical mechanical polish (CMP), a fully packaged MEMS device with thickness <100 μm could be realized. This reduced thickness could prove to be critical, as the consumer electronics market continues to push for smaller (in area and thickness) and cheaper sensors, with ...