AVS 49th International Symposium
    Plasma Science Wednesday Sessions
       Session PS+MM-WeA

Paper PS+MM-WeA7
Deep Silicon Etch Profile Control for Micro-Sensor Applications

Wednesday, November 6, 2002, 4:00 pm, Room C-105

Session: Feature Profile Evolution /Plasma Processing for MEMS
Presenter: R.J. Shul, Sandia National Laboratories
Authors: R.J. Shul, Sandia National Laboratories
M.G. Blain, Sandia National Laboratories
S.G. Rich, Sandia National Laboratories
S.A. Zmuda, Sandia National Laboratories
C.G. Willison, Sandia National Laboratories
R.P. Manginell, Sandia National Laboratories
Correspondent: Click to Email
The ability to etch deep, high-aspect ratio, anisotropic, Si features has opened up new areas of application for microelectromechanical systems (MEMS) devices, as well as revolutionized the conception and implementation of "mixed technology" integration. For example, a fully integrated microsystem could include sensors, actuators, electronics, fluidics, and optics in a variety of material systems on a single chip or in a single package. Fabrication of such structures often requires profile control, multi-level etched features, and the ability to form freestanding membrane structures. For example, Si deep reactive ion etch (DRIE) has been used to fabricate a gas chromatographic (GC) separator as part of a micro-chemical analysis system (µChemLab@superTM@) used for the detection of trace concentrations of gas phase analytes. Maintaining uniform, controlled flow dynamics to optimize device performance requires well-controlled etch profiles and smooth etch morphologies. We will report on the use of the DRIE platform to fabricate anisotropic GC columns 100 µm wide, 400 µm deep with 25 µm walls. To improve the separation sensitivity of the GC columns, a new GC design that incorporates 50 µm diameter posts on 80 µm pitch located within 500 µm deep GC columns has recently been fabricated. A new DRIE process was developed to etch these features using parameter ramping, varying reactive gas flow, pressure, and ion energy. The profiles were very anisotropic with smooth features. The use of parameter ramping as well as multi-level masking processes to meet the challenges of advanced micro-sensor designs will be discussed. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-ACO4-94AL85000. .