Joining method and device produced by this method and joining unit
View Patent ↗A practical bonding technique is provided for solid-phase room-temperature bonding which does not require a profile irregularity of the order of several nanometers, in which a high-vacuum energy wave treatment and continuous high-vacuum bonding are not required. Since an adhering substance layer is thin immediately after a surface activating treatment using an energy wave, a bonding interface is spread by crushing the adhering substance layer to perform bonding, so that a new surface appears on a bonding surface, and objects to be bonded are bonded together. In order to crush the adhering substance layer more easily, a bonding metal of a bonding portion of the object to be bonded needs to have a low hardness. According to the results of various experiments conducted by the present inventors, it was found that the hardness of the bonding portion which is a Vickers hardness of 200 Hv or less is particularly effective for room-temperature bonding.
1. 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.
2. The bonding method according to claim 1 , wherein step (c) is performed in a low vacuum 10 −5 Torr or more in the atmospheric air.
3. The bonding method according to claim 1 , wherein the bonding portions of objects to be bonded are formed of metal which have a hardness of 20 Hv to 200 Hv or less.
4. The bonding method according to claim 1 , wherein the bonding portions of the objects to be bonded are formed of gold.