Patent ID: 9637372
Date: 2017-05-02
CPC Classifications: B81B,B81C

Claim:
1. A method of forming a multi-wafer structure using cap wafer and a device wafer each having a plurality of die, comprising: forming a cavity in a die of the cap wafer; forming a first seal material around the cavity; forming a collapsible standoff structure around the cavity; forming a movable mass in a die of the device wafer; forming a second seal material around the movable mass that is alignable to the first seal material, wherein the first seal material and the second seal material are of materials that are able to form a eutectic bond at a eutectic temperature that is below the melting temperature of each of the first and second seal materials; arranging the cap wafer and the device wafer so that the first and second seals are aligned but separated by the collapsible standoff structure; performing an evacuation of gas from the cavity at a temperature above the eutectic temperature using a vacuum pump; after sufficient time to provide the evacuation of gas, reducing the temperature so that the first and second seal materials are below the eutectic temperature; pressing the cap wafer and device wafer together with sufficient force to cause the first and second seal materials to be in contact; and raising the temperature of the first and second seal materials above the eutectic temperature to form the eutectic bond between the first and second seal materials.