Susceptor for semiconductor substrate processing
A susceptor for semiconductor substrate processing is disclosed herein. In some embodiments, the susceptor may comprise an inner susceptor portion and an outer susceptor portion. The susceptor portions may self-align via complementary features, such as tabs on the outer susceptor and recesses on the inner susceptor portion. The inner susceptor portion may contain several contact pads with which to support a wafer during semiconductor processing. In some embodiments, the contact pads are hemispherical to reduce contact area with the wafer, thereby reducing risk of backside damage. The inner susceptor portion may contain a cavity with which to receive a thermocouple. In some embodiments, the diameter of the cavity is greater than the diameter of the thermocouple such that the thermocouple does not contact the walls of the cavity during processing, thereby providing highly accurate temperature measurements.
1 . A method for processing a substrate, the method comprising:
providing the substrate on a susceptor in a processing chamber, wherein the susceptor comprises an inner susceptor portion and an outer susceptor portion that encircles the inner susceptor portion, and wherein the inner susceptor portion includes a cavity defining a volume for accommodating a thermocouple, the cavity being formed through an underside of a middle portion of the inner susceptor portion, wherein the inner susceptor portion includes a plurality of recesses, and the outer susceptor portion includes a plurality of lobes extending under the inner susceptor portion to support the inner susceptor portion, and wherein each of the lobes has a generally triangular shape, which is defined by sloping sides which extend towards a rounded apex pointed towards the interior of the susceptor, and aligns within a corresponding one of the recesses, wherein the apex of the triangular shape of the lobes protrudes toward a center of the inner susceptor portion;
providing a thermocouple in the cavity, wherein the thermocouple is separated from walls of the cavity by an air gap; and
processing the substrate on the susceptor in the processing chamber,
wherein processing the substrate comprises heating the substrate and the susceptor, wherein the air gap is maintained during substrate processing.
2 . The method of claim 1 , wherein a tip of the thermocouple contacts an upper end of the cavity while processing the substrate.
3 . The method of claim 1 , wherein material forming the thermocouple has a higher coefficient of thermal expansion than material forming the susceptor.
4 . The method of claim 1 , wherein a thickness of the inner susceptor portion above the thermocouple is about 1 mm or more.
5 . The method of claim 1 , wherein the thickness is less than 1.5 mm.
6 . The method of claim 1 , wherein the walls of the cavity define a cylinder.
7 . The method of claim 1 , wherein an upper end of the cavity is flat.
8 . The method of claim 1 , wherein a tip of the thermocouple is hemispherical.