Apparatus and methods for creating a thermal interface bond between a semiconductor die and a passive heat exchanger
A method of joining a semiconductor die to a passive heat exchanger can include applying a bond enhancing agent to a semiconductor device; creating an assembly that includes a thermal interface disposed on the semiconductor device such that a first major surface of the thermal interface material is in touching relation with the bond enhancing agent on the semiconductor device, and a heat exchanger disposed in touching relation with a second major surface of the thermal interface material; and reflowing the assembly such that the thermal interface bonds the heat exchanger to the semiconductor device. Embodiments can use the ability of indium to bond to a non-metallic surface to form the thermal interface, which may be enhanced by a secondary coating on either or both joining surfaces.
1. A method for bonding a semiconductor device to a heat exchanger, comprising:
providing a semiconductor device;
forming an oxide seed layer on a first surface of the semiconductor device by:
applying a bond enhancing agent comprising a bulk liquid metal to a first surface of the semiconductor device; and
removing the bulk liquid metal to leave the oxide seed layer on the first surface of the semiconductor device;
creating an assembly comprising:
a thermal interface comprising a first major surface and a second major surface opposite the first major surface, wherein the thermal interface is disposed on the semiconductor device such that the first major surface of the thermal interface is in touching relation with the oxide seed layer; and
a heat exchanger disposed in touching relation with the second major surface of the thermal interface; and
wherein, the oxide seed layer alloys with the thermal interface and connects the semiconductor device to the thermal interface.
2. The method of claim 1 , wherein the thermal interface comprises an indium metal.
3. The method of claim 1 , wherein the bond enhancing agent comprises at least one of a an organotitanate, and an organozirconate.
4. The method of claim 1 , wherein the semiconductor device is bonded to the heat exchanger without using a separate metallization layer to bond the thermal interface to the semiconductor device.
5. The method of claim 1 , wherein the heat exchanger comprises a heat sink, a heat spreader, or a lid.
6. The method of claim 1 , further comprising applying a bond enhancing agent to a surface of the heat exchanger that is to be disposed in touching relation with the second major surface of the thermal interface.
7. The method of claim 1 , wherein the liquid metal comprises gallium.
8. The method of claim 1 , wherein the liquid metal comprises indium and gallium.