Patent ID: 8091764

Claim:
A bonding method for bonding objects to be bonded having a bonding portion formed of metal, comprising the following steps: (a) removing impurities around the objects to be bonded by evacuating to reduce pressure; (b) introducing an inert reaction gas; (c) etching the bonding portions of the objects to be bonded with an energy wave which is an atom beam, an ion beam, or a plasma to thereby clean the bonding portions of adhering substances and generate an active dangling bond of a metal atom on a bonding surface of the bonding portions; (d) contacting the bonding portions of the objects to be bonded with each other; and (e) crushing minute irregularities on a bonding surface of the bonding portions in contact with each other to thereby bond to the objects to be bonded together, wherein after step (c) and prior to step (d) at least some of the adhering substance readhere to the bonding portions to thereby form an adhering substance layer, step (e) causes a bonding interface between the bonding portions to spread by spreading the adhering substance layer which causes new metal surface to appear at the bonding interface so that bonding is achieved between the bonding portions, step (d) and (e) are each performed in a solid phase at a temperature between room temperature and 180° C., and at least one of the bonding portions in step (e) has a surface roughness Ry of 120 nm or more.