In this paper we report fabrication of a shadow mask designed for sputtering into cavities or on the back surface of freestanding silicon nitride (SiNx) membranes. Sputter deposition through a shadow mask typically results in spreading of the deposited material. The area of spreading depends on the vertical separation between the shadow mask and the surface. The current shadow mask is designed to stand about 25 micrometers from the membrane which results in spread of abut 40 micrometer. The shadow mask is made from nitride coated silicon wafers, using KOH etching on both sides of the wafer. The design, fabrication and methods used for convex-corner compensation, and the alignment to wafer cystal axis to achieve an accurate fit between the shadow mask and the sensor, are discussed.
Citation: Journal of Microelectromechanical Systems
Pub Type: Journals