JUNCTION OF SEMICONDUCTOR WAFERS

PURPOSE:To easily attain rigid junction of semiconductor wafers having large areas by finishing the surface of two sheets of semiconductor wafers like the mirror-surface, placing the ground surfaces of them in the close contact under a reduced pressure, placing them again under the atmospheric pressure and executing the heat processing at a particular temperature. CONSTITUTION:It is desirable that the surface roughness of ground surfaces is set to 500Angstrom or less and after the grinding the surfaces are washed sufficiently, the surfaces are dried up and placed in close contact within a chamber under the reduced pressure. When a pressure within the chamber of reduced pressure is set to 10mTorr or less, good contactness can be attained because residual gas such as air can substantially be disregarded. The heat processing under the atmospheric pressure brings about effective increase in injuction strength of wafers when temperature is 200 deg.C or hither. Particularly, the heat processing at a temperature of about 1,000 deg.C is desirable in order to attain good electrical characteristics. When temperature rises upto 1,300 deg.C or higher, deformation of wafer such as creep is generated as in the case of conventional hot-press method. If a foreign matter such as dust is adhered to the bonding surface, good junction body cannot be obtained. Therefore, purification of ambient is very important for the processes from washing of wafer to junction.