Susceptor with backside area of constant emissivity
Methods and apparatus for providing constant emissivity of the backside of susceptors are provided. Provided is a susceptor comprising: a susceptor plate having a surface for supporting a wafer and a backside surface opposite the wafer supporting surface; a layer comprising an oxide, a nitride, an oxynitride, or combinations thereof located on the backside surface of the susceptor plate, the layer being stable in the presence of a reactive process gas. The layer comprises, for example, silicon dioxide, silicon nitride, silicon oxynitride, or combinations thereof. Also provided is a method comprising: providing a susceptor in a deposition chamber, the susceptor comprising a susceptor plate and a layer comprising an oxide, a nitride, an oxynitride, or combinations thereof, the layer being stable in the presence of the reactive process gases; locating the wafer on a support surface of the susceptor plate. The method can further comprises selectively depositing an epitaxial layer or a non-epitaxial layer on a surface of the wafer. The method further comprises selectively etching to maintain the oxide, nitride, oxynitride, or combinations thereof layer.
1. An apparatus for depositing material on a surface of a wafer, the apparatus comprising:
a deposition chamber;
an inlet for a reactive process gas to form deposited material within the chamber;
a susceptor plate extending across the deposition chamber and having a surface for supporting a wafer and a backside surface opposite the wafer supporting surface;
an infrared temperature sensor facing the backside of the susceptor to provide a viewing area for the temperature sensor; and
a layer comprising an oxide, a nitride, an oxynitride, or combinations thereof covering an area consisting of only a portion of the backside surface of the susceptor plate, wherein the layer has a radius less than a radius of the susceptor plate such that a portion of the backside surface of the susceptor plate is free of the layer, the layer being stable in the presence of a reactive process gas and effective to inhibit deposited material from forming a film on the layer.
2. The apparatus of claim 1 , wherein the layer comprises silicon.
3. The apparatus of claim 1 , wherein the layer has a radius in the range of 25 to 50 mm.
4. The apparatus of claim 1 , wherein the reactive process gas comprises hydrogen chloride, chlorine, a silicon-containing gas, diborane, phosphine, germanium, arsine, hydrogen, or combinations thereof.
5. The apparatus of claim 4 , wherein the reactive process gas comprises a silicon-containing gas selected from the group consisting of: dichlorosilane, silane, disilane, and trisilane.
6. The apparatus of claim 1 , wherein the susceptor plate comprises graphite.
7. The apparatus of claim 6 , wherein the susceptor plate has a silicon carbide coating.
8. The apparatus of claim 1 , wherein the susceptor plate comprises silicon carbide.
9. The apparatus of claim 1 , wherein the layer comprises silicon dioxide, silicon nitride, silicon oxynitride, or combinations thereof.
10. The apparatus of claim 1 , wherein the infrared temperature sensor facing the backside surface of the susceptor plate is adapted to detect radiation emitted from the susceptor when the susceptor is heated.
11. The apparatus of claim 10 , wherein the layer covers an area on the susceptor plate that substantially coincides with the viewing area of the infrared temperature sensor.
12. The apparatus of claim 1 , wherein the infrared temperature sensor is calibrated to the emissivity of the layer.