Electrical Resistance Heater and Heater Assemblies

Abstract

A system for processing substrates is described. In one embodiment, the system comprises a process chamber, at least one electrical resistance heater, and at least one Coanda effect gas injector.

What is claimed is: 
     
         1 . A system for processing one or more substrates, the system comprising:
 a process chamber;   a substrate support disposed in the process chamber to hold one or more substrates; and   at least one electrical resistance heater comprising a sinusoidal heating element having a plurality of peaks disposed to delineate an outer radius and a plurality of troughs disposed to delineate an inner radius; the cross-section width of the heating element being a first function of radial position and the cross-section thickness of the heating element being a second function of radial position so that the heating element provides a substantially constant heat flux at each radial position and forms a substantially constant spacing between facing side surfaces of the heating element, the at least one electrical resistance heater being disposed so as to heat the substrate support and/or the one or more substrates.   
     
     
         2 . The system of  claim 1 , further comprising:
 at least one Coanda effect gas injector disposed proximate a peripheral edge of the substrate support so as to provide a Coanda effect gas flow over the surface of the substrate support and/or the one or more substrates.   
     
     
         3 . The system of  claim 2 , wherein the at least one Coanda effect gas injector has a gas exit port, a gas flow channel, and a gas entry port; the gas exit port is in fluid communication with the gas flow channel, the gas flow channel is in fluid communication with the gas entry port; the gas flow channel is formed by at least one convex surface of the Coanda effect gas injector to produce the Coanda effect gas flow. 
     
     
         4 . The system of  claim 2 , wherein the at least one Coanda effect gas injector has a gas entry port, a plenum, a gas flow channel, and a gas exit port; the gas exit port is in fluid communication with the plenum via the gas flow channel, the gas entry port is in fluid communication with the plenum, the gas flow channel is formed by at least one convex surface of the Coanda effect gas injector so as to produce the Coanda effect gas flow. 
     
     
         5 . The system of  claim 2 , further comprising a rotary coupling connected with the substrate support for rotating the surface of the substrate support. 
     
     
         6 . The system of  claim 2 , further comprising a linear actuator connected with the substrate support for linear translation of the surface of the substrate support. 
     
     
         7 . The system of  claim 2 , wherein the process chamber is a hot wall chamber for elevated temperature processes. 
     
     
         8 . The system of  claim 2 , wherein the process chamber, the substrate support, and the at least one Coanda effect gas injector comprise materials selected from the group consisting of aluminum oxide, aluminum nitride, silicon carbide, silicon nitride, silicon dioxide, stainless steel, graphite, and silicon carbide coated graphite. 
     
     
         9 . The system of  claim 2 , wherein the cross-section thickness of the sinusoidal heating element is a function of the form f(1/r) where r is radial position on the heater. 
     
     
         10 . The system of  claim 2 , wherein the cross-section width of the sinusoidal heating element is a function of the form f(r) where r is radial position on the heater. 
     
     
         11 . The system of  claim 2 , wherein the cross-section thickness of the sinusoidal heating element is derived from the equation:
     t= 2π r   i   2   Gt   i /(2π r   2   G−Sr )
   where   t is the cross-section thickness of the heating element,   r is the radial position on the heating element,   π is the mathematical constant pi,   r i  is the inside radius of the heating element,   t i  is the initial trial thickness,   G is a geometry factor equaling the angular width of the heating element spoke divided by the angular size of the heater, and   S is the spacing between facing side surfaces of the heating element.   
     
     
         12 . The system of  claim 2 , wherein the cross-section width of the sinusoidal heating element is derived from the equation:
     w= 2 πGr−S      where   w is the cross-section width of the heating element,   r is the radial position on the heating element,   π is the mathematical constant pi,   G is a geometry factor equaling the angular width of the heating element spoke divided by the angular size of the heater, and   S is the spacing between facing side surfaces of the heating element.   
     
     
         13 . The system of  claim 2 , wherein the at least one electrical resistance heater comprises graphite coated with silicon carbide. 
     
     
         14 . The system of  claim 2 , wherein the heating element comprises a material selected from the group consisting of nickel-chromium alloy, molybdenum, tantalum, and tungsten. 
     
     
         15 . The system of  claim 2 , wherein the at least one electrical resistance heater further comprises electrical contacts and electrical adapters press-fit coupled thereto. 
     
     
         16 . The system of  claim 2 , further comprising a secondary gas injector disposed so as to provide a gas flow to the process chamber. 
     
     
         17 . A system for processing one or more substrates, the system comprising:
 an outer chamber;   a process chamber disposed substantially within the outer chamber;   a substrate support disposed in the process chamber to hold one or more substrates;   at least one electrical resistance heater comprising a sinusoidal heating element having a plurality of peaks disposed to delineate an outer radius and a plurality of troughs disposed to delineate an inner radius; the cross-section width of the heating element being a first function of radial position and the cross-section thickness of the heating element being a second function of radial position so that the heating element provides a substantially constant heat flux at each radial position and forms a substantially constant spacing between facing side surfaces of the heating element, the at least one electrical resistance heater comprising pyrolytic graphite electrical contacts and pyrolytic graphite electrical adapters press-fit coupled thereto and a thermally deposited silicon carbide overcoating, the at least one electrical resistance heater being disposed between the outer chamber and the process chamber so as to heat the substrate support and/or the one or more substrates;   at least one Coanda effect gas injector disposed proximate a peripheral edge of the substrate support so as to provide a Coanda effect gas flow over the surface of the substrate support and/or the substrates, the at least one Coanda effect gas injector having a gas entry port, a plenum, a gas flow channel, and a gas exit port; the gas exit port being in fluid communication with the plenum via the gas flow channel, the gas entry port being in fluid communication with the plenum, the gas flow channel being formed by at least one convex surface of the Coanda effect gas injector so as to produce a Coanda effect gas flow;   at least one secondary gas injector disposed so as to provide a gas flow to the process chamber; and   a rotary coupling connected with the substrate support for rotating the substrate support;   wherein the cross-section thickness of the sinusoidal heating element is derived from the equation:
     t= 2π r   i   2   Gt   i /(2π r   2   G−Sr )
 
   where   t is the cross-section thickness of the heating element,   r is the radial position on the heating element,   π is the mathematical constant pi,   r i  is the inside radius of the heating element,   t i  is the initial trial thickness,   G is a geometry factor equaling the angular width of the heating element spoke divided by the angular size of the heater, and   S is the spacing between facing side surfaces of the heating element;   wherein the cross-section width of the sinusoidal heating element is derived from the equation:
     w= 2π Gr−S  
 
   where   w is the cross-section width of the heating element,   r is the radial position on the heating element,   π is the mathematical constant pi,   G is a geometry factor equaling the angular width of the heating element spoke divided by the angular size of the heater, and   S is the spacing between facing side surfaces of the heating element.   
     
     
         18 . A method of processing a substrate, the method comprising:
 providing a substrate;   providing one or more reactive gases;   providing at least one heater or heater assembly comprising a sinusoidal heating element having a plurality of peaks disposed to delineate an outer radius and a plurality of troughs disposed to delineate an inner radius; the cross-section width of the heating element being a first function of radial position and the cross-section thickness of the heating element being a second function of radial position so that the heating element provides a substantially constant heat flux at each radial position and forms a substantially constant spacing between facing side surfaces of the heating element, and   applying heat to the substrate with the at least one heater or heating assembly and creating a Coanda effect gas flow of the one or more reactive gases over the substrate.   
     
     
         19 . The method  claim 18 , further comprising rotating the substrate. 
     
     
         20 . The method  claim 18 , wherein the providing the substrate comprises providing a semiconductor wafer. 
     
     
         21 . The method  claim 18 , wherein the providing the substrate comprises providing a substrate for fabricating electronic or optoelectronic devices. 
     
     
         22 . The method  claim 18 , wherein the providing the substrate comprises providing a silicon wafer. 
     
     
         23 . The method  claim 18 , wherein the providing the one or more reactive gases comprises providing one or more precursors for semiconductor deposition. 
     
     
         24 . The method  claim 18 , wherein the providing the one or more reactive gases comprises providing a silicon precursor. 
     
     
         25 . The method  claim 18 , wherein the providing the one or more reactive gases comprises providing a compound selected from the group consisting of silane, dichlorosilane, trichlorosilane, and silicon tetrachloride. 
     
     
         26 . The method  claim 18 , further comprising maintaining conditions sufficient to cause deposition of epitaxial silicon. 
     
     
         27 . The method  claim 18 , wherein the providing one or more reactive gases comprises providing one or more precursors for deposition of group IV element semiconductors, group IV element compound semiconductors, group III-V element semiconductors, or group II-VI element semiconductors. 
     
     
         28 . The method  claim 18 , further comprising maintaining conditions sufficient to cause deposition of an epitaxial layer.