Sputtering target temperature control utilizing layers having predetermined emissivity coefficients
A sputter coating apparatus for sputter coating a substrate in a processing chamber includes a target of sputter coating material supported within the processing chamber. The target has a sputtering surface and a back surface. The target is affixed to a backing plate such that the back surface of the target is disposed adjacent to a first surface of the backing plate. The backing plate is in fluid communication with a source of cooling fluid. The target back surface has a first layer selected to have a high thermal emissivity coefficient. The backing plate first surface carries a second layer having a high emissivity coefficient. The target back surface first layer and the backing plate first surface second layer provide enhanced heat transfer between the target and the backing plate via thermal radiation.
1. A sputter coating apparatus for sputter coating a substrate in a processing chamber, said processing chamber being sealable to provide a vacuum therein, said apparatus comprising:
a target of sputter coating material supported within said processing chamber, said target having a sputtering surface and a back surface;
a backing plate coupled to said target with micro-surface roughness resulting in a maximum of 5% contact area between the back surfaces and said backing plate, said backing plate being in fluid communication with a source of cooling fluid, said backing plate having a first surface disposed next to the back surface of said target;
a layer on the first surface of said back plate, said layer having a high emissivity coefficient greater than 0.3 such that radiation heat transfer between said target and said backing plate is improved.
2. The sputter coating apparatus in accordance with claim 1 , wherein: said layer is oxidized metal.
3. The sputter coating apparatus in accordance with claim 1 , wherein: the high emissivity coefficient is greater than 0.7.
4. The sputter coating apparatus in accordance with claim 1 , further comprising: a target back surface layer applied to the back surface of said target, said target back surface layer having an emissivity coefficient greater than 0.3.
5. The sputter coating apparatus in accordance with claim 4 , wherein: the emissivity coefficient is greater than 0.7.
6. The sputter coating apparatus in accordance with claim 4 , wherein: said layer is formed of one of: oxidized stainless steel, oxidized nickel, mild steel, oxidized Inconel X, oxidized copper, oxidized brass, anodized aluminum, alloy 24ST, or flame sprayed alumina.