QUARTZ ENCAPSULATED HEATER ASSEMBLY
The current invention relates to a semiconductor wafer heater assembly having a frosted clear quartz material for the wafer susceptor ( 6 ) that is placed between the heater ( 8 ) and the wafer ( 7 ) such that at certain wavelengths of the emitted radiant energy from the heater ( 8 ), the frosted clear quartz material is ‘thermally transmissive’ to the thermal radiation from the infrared region. The heater assembly is characterized in that the top quartz plate or susceptor ( 6 ) on which the wafer ( 7 ) is supported is made of a material that is not “optically transmissive” but is more than 90% “thermally transmissive” to infrared emission that is shorter than 3.5 micrometer wavelength and having higher tolerance and mechanical strength than conventional clear quartz material.
1 . A heater assembly comprising a heating element to heat a wafer to temperatures of at least 700 Degrees C., at least one terminal and wire to feed electrical power to the heater, a thermal insulating plate beneath the heater, at least one feed through hole for the electrical wire and at least one thermo-couple connection, and a quartz casing to encapsulate said components, said quartz casing having a top plate positioned between the heating element and the wafer, wherein said plate comprises a material that is not optically transmissive and is more than 50 percent thermally transmissive to an infrared emission that is shorter than 3.5 micron wavelength.
2 . The heater assembly of claim 1 , wherein the top plate comprises frosted clear quartz.
3 . The heater assembly of claim 2 , wherein the frosted clear quartz has thermal transmissivity of at least 80 percent.
4 . The heater assembly of claim 2 , wherein the frosted clear quartz has thermal transmissivity of at least 90 percent.
5 . The heater assembly of claim 1 , wherein all the components inside the quartz casing are completely isolated from the chamber environment by sealing the top plate and quartz casing by bonding.
6 . The heater assembly of claim 1 , wherein the top plate is made of frosted clear quartz and fusion bonded to the quartz casing.
7 . The heater assembly of claim 1 , wherein the quartz casing other than the top plate is prepared from clear quartz.
8 . The heater assembly of claim 1 , wherein the top plate is more than 50 percent thermally transmissive to an infrared emission that is shorter than 3.2 micron wavelength.
9 . The heater assembly of claim 1 , wherein the top plate is more than 80 percent thermally transmissive to an infrared emission that is shorter than 3.2 micron wavelength.
10 . The heater assembly of claim 1 , wherein the top plate is more than 90 percent thermally transmissive to an infrared emission that is shorter than 3.2 micron wavelength.
11 . A semiconductor processing chamber comprising the heater assembly of claim 1 .