AVS 49th International Symposium
    Microelectromechanical Systems (MEMS) Wednesday Sessions
       Session MM-WeP

Paper MM-WeP9
Deep Reactive Ion Etching of Silicon Using an Aluminum Etching Mask

Wednesday, November 6, 2002, 11:00 am, Room Exhibit Hall B2

Session: Poster Session
Presenter: W. Wang, University of Washington
Authors: W. Wang, University of Washington
P. Reinhall, University of Washington
Correspondent: Click to Email
A novel double-sided micromachining process for the silicon based device fabrication has been developed that allows the use of capacitively coupled RIE equipment for high aspect ratio etching. The resulting etch rates in Si of 2.2 µm/min is comparable to 1 to 3 µm/min from the standard ICP deep reactive ion etching process. Although a lower anisotropy (~0.5) and lower selectivity to thermal oxide (Si: SiO@sub 2@ = 10:1) and to photoresist (Si: +PR = 9:1) resulted, the proposed process is much simpler and requires only the use of an aluminum mask. Based on the experimental results, a 1000 Å thick Al film sufficiently protects the unexposed substrate while allowing the etching of a 350µm deep hole with an area of 3x3mm@super 2@ when etching with SF@sub 6@ /CHF@sub 3@/O@sub 2@ plasma. A 2000µm long and 100µm wide (with layers of Al/SiO@sub 2@/Si and thicknesses of 0.1µm/2.2µm/40µm respectively) cantilever is also achieved. The technique was developed mainly for bulk micromachining of silicon or composite silicon cantilever structures.