IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Microelectromechanical Systems (MEMS) Thursday Sessions
       Session MM-ThA

Paper MM-ThA6
Fabrication of Novel Si@sub 3@N@sub 4@ Micromesh Spider Web Bolometer Using Deep Trench Etching on SOI Wafer

Thursday, November 1, 2001, 3:40 pm, Room 130

Session: Fabrication and Integration Processes for MEMS
Presenter: M.H. Yun, Jet Propulsion Laboratory, Caltech-NASA
Authors: M.H. Yun, Jet Propulsion Laboratory, Caltech-NASA
A.M.P. Turner, Jet Propulsion Laboratory
J.J. Bock, Jet Propulsion Laboratory
J.A. Podosek, Jet Propulsion Laboratory
Correspondent: Click to Email
Bolometers are used for sensitive detection of radiation throughout the electromagnetic spectrum, from X-ray to millimeter-wave. The sensitivity of a bolometer can be improved by reducing its base temperature, and reducing its thermal conductivity. Sub-millimeter wave bolometers have achieved a steady increase in sensitivity over the past decade. In this research, we have fabricated and developed extremely sensitive Si@sub 3@N@sub 4@ micromesh spider web bolometers for sub-millimeter astrophysics using microelectromechanical system (MEMS) techniques. The spider-web architecture provides high infrared absorption with minimal heat capacity and volume. We use silicon-on-insulator (SOI) bonded wafers, with a 2 µm of top silicon layer, a 1 µm SiO@sub 2@ insulating layer, and a 350 µm of bottom silicon layer, to fabricate the devices. Using a deep trench reactive ion etching (RIE) from the bottom silicon to the insulating layer, followed by wet etching to remove SiO@sub 2@, a 151-element polygonal spider web array was formed on the 4" SOI wafer. We also observed that the deep trench etching may result in less surface roughness and higher conductivity in the silicon nitride supports. To achieve the best accuracy performance, e-beam lithography is also employed to form contact pad layer. Several Au depositions using photolithography processes form the absorber for optimal infrared absorption, the electrical leads which define the thermal conductance, and the wiring layer for electrical readout. Another silicon wafer is patterned and etched to rest behind the array wafer, forming @lambda@/4 backshorts for maximum optical efficiency. The use of MEMS techniques in this research has improved the sensitivity and format of bolometer arrays. The fabrications of various sub-millimeter device arrays are under development at JPL/Caltech-NASA.