Directed reagents to improve material uniformity

Abstract

A method for locally controlling the stoichiometry of an epitaxially deposited layer on a semiconductor substrate is provided. The method includes directing a first reactant gas and a doping gas across a top surface of a semiconductor substrate and directing a drive gas and a second reactant gas against the substrate separately from the first reactant gas in a manner that rotates the substrate while introducing the second reactant gas at an edge of the substrate to control each reactant separately, thereby compensating and controlling depletion effects and improving doping uniformity in resulting epitaxial layers on the substrate.

1 - 17 . (canceled) 
     
     
         18 . An apparatus for forming uniformly-doped epitaxial layers on a substrate, the apparatus comprising:
 a reactor including therein:   at least one satellite positioned on a top surface of a platter for positioning substrates for epitaxial deposition, said satellite being positioned such that it levitates and rotates relative to said platter;   said platter being positioned on a top surface of a base member and configured for positioning multiple satellites;   said base member including a gas entrance channel;   said gas entrance channel extending through said base member of a susceptor, said gas entrance channel being configured to include entrance for at least one reactant gas; and   a reactant gas entrance passage above said satellite for introducing reactant gases to said reactor, said reactant gas entrance passage being positioned relative to said satellite such that said reactant gases travel across a top surface of said satellite.   
     
     
         19 . An apparatus for forming uniformly-doped epitaxial layers on a substrate according to  claim 18  comprising more than one satellite positioned on said top surface of said platter for positioning substrates for epitaxial deposition. 
     
     
         20 . An apparatus for forming uniformly-doped epitaxial layers on a substrate according to  claim 19  wherein a first drive gas channel is configured such that it is in communication with each of said satellites. 
     
     
         21 . An apparatus for forming uniformly-doped epitaxial layers on a substrate according to  claim 18  further comprising a spindle between said platter and said base member. 
     
     
         22 . An apparatus for forming uniformly-doped epitaxial layers on a substrate according to  claim 18  further comprising a drive gas supply device operative to provide a flow of drive gas through said gas entrance channel. 
     
     
         23 . An apparatus for forming uniformly-doped epitaxial layers on a substrate according to  claim 18  further comprising a reactant gas supply device operative to provide a flow of reactant gas through said gas entrance channel. 
     
     
         24 . An apparatus for forming uniformly-doped epitaxial layers on a substrate according to  claim 18  further comprising an exhaust passage for exhausting the reactant gases from the reactor after epitaxial deposition. 
     
     
         25 . A method for forming uniformly-doped epitaxial layers on a substrate, the method comprising: coating a top surface of a satellite with a source substance that is capable of releasing reactant atoms upon heating;
 positioning a substrate on the source substance opposite the top surface of the satellite such that the source substance is introduced to the substrate at the edge of the substrate;   positioning a bottom surface of the satellite on an indented top surface of a platter configured for multiple satellites in a reactor, the bottom surface of the satellite being in communication with a first drive gas channel, the platter being on a base member including a gas entrance channel;   directing a reactant gas and a doping gas across a top surface of the substrate, at least in part using the gas entrance channel; and   directing a drive gas through the first drive gas channel such that the satellite is rotated relative to the platter.   
     
     
         26 - 27 . (canceled) 
     
     
         28 . The method of forming uniformly-doped epitaxial layers according to claim  27  further comprising the step of effecting epitaxial deposition on the top surface of the substrate. 
     
     
         29 . The method of forming uniformly-doped epitaxial layers on a substrate according to  claim 28  wherein the step of effecting epitaxial deposition on the top surface of the substrate comprises depositing an epitaxial layer in an atmosphere that is relatively silicon-rich near the center of the substrate surface. 
     
     
         30 . The method of forming uniformly-doped epitaxial layers on a substrate according to  claim 28  wherein the step of effecting epitaxial deposition on the top surface of the substrate comprises depositing an epitaxial layer in an atmosphere that is relatively carbon-rich near the edge of the wafer. 
     
     
         31 . The method of forming uniformly-doped epitaxial layers on a substrate according to  claim 28  wherein the step of effecting epitaxial deposition on the top surface of the substrate comprises depositing an epitaxial layer having a substantially uniform doping profile. 
     
     
         32 . The method of forming uniformly-doped epitaxial layers on a substrate according to  claim 25  wherein the step of directing a reactant gas across a top surface of the substrate comprises directing a silicon-rich reactant gas. 
     
     
         33 . The method of forming uniformly-doped epitaxial layers on a substrate according to  claim 32  wherein the step of directing a silicon-rich reactant gas comprises directing silane gas. 
     
     
         34 . The method of forming uniformly-doped epitaxial layers on a substrate according to  claim 25  wherein the step of directing a doping gas comprises directing a doping gas comprising n-type dopant atoms. 
     
     
         35 . The method of forming uniformly-doped epitaxial layers on a substrate according to  claim 34  wherein the step of directing a doping gas comprising n-type dopant atoms comprises directing a doping gas including atoms selected from the group consisting of N, P, As, Sb, Bi, and combinations thereof. 
     
     
         36 . The method of forming uniformly-doped epitaxial layers on a substrate according to  claim 25  wherein the step of directing a doping gas comprises directing a doping gas comprising p-type dopant atoms. 
     
     
         37 . The method of forming uniformly-doped epitaxial layers on a substrate according to  claim 36  wherein the step of directing a doping gas comprising p-type dopant atoms comprises directing a doping gas including atoms selected from the group consisting of B, Al, Ga, In, Tl, and combinations thereof. 
     
     
         38 . The method of forming uniformly-doped epitaxial layers on a substrate according to  claim 25  wherein the step of directing a drive gas through a second drive gas channel comprises directing a drive gas selected from the group consisting of noble gases, hydrogen, and combinations thereof 
     
     
         39 . The method of forming uniformly-doped epitaxial layers on a substrate according to claim  26  wherein the step of coating a top surface of a satellite with a carbon-containing substance comprises coating the satellite with graphite. 
     
     
         40 . The method of forming uniformly-doped epitaxial layers on a substrate according to  claim 25  wherein the step of coating a top surface of a satellite comprises coating with a composition that includes a source element for a compound semiconductor. 
     
     
         41 . The method of forming uniformly-doped epitaxial layers on a substrate according to  claim 25  wherein the step of coating a top surface of a satellite with a carbon-containing substance comprises coating a satellite previously coated with tantalum chloride. 
     
     
         42 - 65 . (canceled) 
     
     
         66 . A method for forming uniformly-doped epitaxial layers on a substrate, the method comprising:
 positioning a substrate in a reactor for epitaxial deposition, the substrate being positioned on a rotatable platform;   directing a first reactant gas and a doping gas from a first gas inlet across a top surface of the substrate;   while concurrently directing a second reactant gas from a second gas inlet across the top surface of the substrate.   
     
     
         67 . The method of forming uniformly-doped epitaxial layers on a substrate according to  claim 66  wherein the step of directing a second reactant gas from a second gas inlet across comprises directing a second reactant gas from a second gas inlet that is positioned between the first gas inlet and the rotatable platform. 
     
     
         68 . The method of forming uniformly-doped epitaxial layers on a substrate according to  claim 66  wherein the steps of directing a first reactant gas across the top surface of the substrate while concurrently directing a second reactant gas across the top surface of the substrate further comprises rotating the platform. 
     
     
         69 . The method of forming uniformly-doped epitaxial layers on a substrate according to  claim 68  wherein the step of rotating the platform comprises rotating the platform mechanically. 
     
     
         70 . The method of forming uniformly-doped epitaxial layers on a substrate according to  claim 68  wherein the step of rotating the platform comprises gas-driven rotation. 
     
     
         71 . The method of forming uniformly-doped epitaxial layers on a substrate according to  claim 66  wherein the step of directing a reactant gas and a doping gas across a surface of a substrate comprises directing a relatively silicon-rich reactant gas across the surface of the substrate. 
     
     
         72 . The method of forming uniformly-doped epitaxial layers on a substrate according to  claim 66  wherein the step of directing a relatively silicon-rich reactant gas comprises directing silane gas. 
     
     
         73 . The method of forming uniformly-doped epitaxial layers on a substrate according to  claim 66  wherein the step of directing a doping gas comprises directing a doping gas comprising n-type dopant atoms. 
     
     
         74 . The method of forming uniformly-doped epitaxial layers on a substrate according to  claim 73  wherein the step of directing a doping gas comprising n-type dopant atoms comprises directing a doping gas including atoms selected from the group consisting of N, P, As, Sb, Bi, and combinations thereof. 
     
     
         75 . The method of forming uniformly-doped epitaxial layers on a substrate according to  claim 66  wherein the step of directing a doping gas comprises directing a doping gas comprising p-type dopant atoms. 
     
     
         76 . The method of forming uniformly-doped epitaxial layers on a substrate according to  claim 75  wherein the step of directing a doping gas comprising p-type dopant atoms comprises directing a doping gas including atoms selected from the group consisting of B, Al, Ga, In, Tl, and combinations thereof. 
     
     
         77 . The method of forming uniformly-doped epitaxial layers on a substrate according to  claim 66  wherein the step of directing a second reactant gas from a second gas inlet across the top surface of the substrate comprises directing a carbon-containing second reactant gas through the second gas channel. 
     
     
         78 . The method of forming uniformly-doped epitaxial layers on a substrate according to  claim 77  wherein the step of directing a carbon-containing second reactant gas comprises directing a gas selected from the group consisting of methane, ethylene, ethane, propane, butane, pentane, hexane, heptane, and combinations thereof. 
     
     
         79 . The method of forming uniformly-doped epitaxial layers on a substrate according to  claim 66  wherein the step of depositing a uniformly-doped epitaxial layer on the substrate comprises depositing an epitaxial layer in a relatively silicon-rich atmosphere near the center of the substrate surface. 
     
     
         80 . The method of forming uniformly-doped epitaxial layers on a substrate according to  claim 66  wherein the step of depositing a uniformly-doped epitaxial layer on the substrate comprises depositing an epitaxial layer in a relatively carbon-rich atmosphere near the edge of the wafer. 
     
     
         81 . The method of forming uniformly-doped epitaxial layers on a substrate according to  claim 66  wherein the step of depositing a uniformly-doped epitaxial layer on the substrate comprises depositing an epitaxial layer having a substantially flat doping profile.