SD-2: Silicon to Glass Bonding Wafers - HOYA - #1

Text version of the page

PRODUCT DESCRIPTION FEATURES APPLICATIONS Matching CTE to Si Wafer No Phase Separation Optimized for Anodic Bonding Reduced Fresnel Diffraction High Flatness Mask High Young's Modulus HOYA's SD-2 substrate is designed with a coefficient of thermal expansion curve which closely matches Si single crystal. Silicon Wafer Bonding Photolithography Pressure Sensors Displacement Sensors Semiconductor THERMAL EXPANSION PROPERTIES Borosilicate glass has been widely used as a bonding material to Silicon Wafer. CTE curves of Borosilicate glass and Silicon Single Crystal Wafer cross at about 240 C. When anodic bonding is performed at 400 C, the difference of the expansions at high temperature creates residual stress in the Si chip during cooling to room temperature. As precision of LSI circuit patterning moves to less than 0.25 microns, distortion between the silicon and glass wafers becomes a critical issue. HOYA's SD-2 substrate is engineered to minimize the distortion or bowing effect caused by the thermal mismatch between the two wafers. ANODIC BONDING Silicon and glass wafers are generally put together by way of Anodic Bonding. This bonding is formed when positive (+) DC voltage is applied to the Si wafer and negative (-) is applied to the glass wafer while the wafers are pressed and heated. During the bonding process, a small amount of Na ions, engineered into SD-2, move as electroconductive carriers to facilitate a very short bonding time. + -7 T ( C) 25 30 35 40 45 0 100 200 300 400 500 600 Si SD-2 + Coefficient of Thermal Expansion Curve )K/ 01 x ( ETC Borosilicate HOYA CORPORATION USA Optics Division 3400 Edison Way Fremont, CA 94538 800-818-HOYA (4692) 510-252-8370 510-490-1988 fax www.hoyaoptics.com SD-2 Glass Substrate for Silicon Sensors