Patent ID: 9056764
Filing Date: 2015-06-16
Classification: B81C,G02B,H01L,Y10T

Abstract:
1. A method comprising: providing a packaging substrate having a first ceramic or glass substrate layer with a concave upper surface that forms a cavity, a second ceramic or glass substrate layer with a lower surface joined to the first layer upper surface peripherally surrounding the cavity and with an upper surface, and a heater comprising a metallic film formed integrally with the packaging substrate between the joined lower first and upper second substrate layer surfaces, wherein the heater is located at a distance of 1-10 mm below the upper surface of the second substrate layer; providing a cover substrate comprising transparent material at least in a portion configured to overlie the cavity when the cover substrate is joined to the packaging substrate; depositing a first metallic film layer peripherally on a lower surface of the cover substrate; depositing a second metallic film layer peripherally of the cavity on the upper surface of the packaging substrate; attaching a microelectromechanical system (MEMS) device within the cavity; and bonding the cover substrate peripherally to the packaging substrate so as to enclose the device within the cavity between the bonded cover and packaging substrates; wherein the bonding comprises disposing a metallic soldering material between the first and second metallic film layers, the metallic soldering material having a soldering temperature less than a melting temperature of the metallic film layers; and applying heat locally by driving an electric current through the heater to melt the soldering material without melting the metallic film layers and without raising a temperature of the device to the soldering temperature, wherein the soldering temperature is less than 300° C. and wherein the heat is applied without raising the temperature of the device to a temperature of 70° C.