Patent ID: 8091601

Claim:
A bonding apparatus for bonding two substrates together by direct molecular adhesion of their insulating or semiconducting surfaces without application of any adhesive material, the apparatus comprising: a support on which is placed a first substrate, and a second substrate placed upon the first substrate, each substrate having a first surface that has a flatness sufficient to facilitate direct molecular bonding by propagation of a bonding front when the first surfaces of the substrates are placed in contact with each other, and a second surface that is opposite to the first surface; means for initiating direct molecular bonding of the substrates that is arranged to apply a force at a selected single, discrete location upon the surface of the second substrate so that the first surfaces contact and a bonding front arises at the selected single, discrete location and propagates between the first surfaces; means for modifying, prior to adhesion, the surface state of one or both of the substrates to be directly molecularly bonded comprising a heater arranged to apply heat directly to only a peripheral region of a surface of one or both substrates to regulate propagation speed of the bonding front to reduce bubble or voids between the substrates after bonding, wherein the heating is performed a temperature of between about 30° C. and 90° C. and is applied only in the peripheral region of the substrate to be bonded.