Self cleaning large scale method and furnace system for selenization of thin film photovoltaic materials

Abstract

A method for fabricating a copper indium diselenide semiconductor film using a self cleaning furnace is provided. The method includes transferring a plurality of substrates having a copper and indium composite structure into a furnace comprising a processing region and at least one end cap region disengageably coupled to the processing region. The method also includes introducing a gaseous species including a hydrogen species and a selenium species and a carrier gas into the furnace and transferring thermal energy into the furnace to increase a temperature from a first temperature to a second temperature to initiate formation of a copper indium diselenide film on each of the substrates. The method further includes decomposing residual selenide species from an inner region of the process region of the furnace. The method further includes depositing elemental selenium species within a vicinity of the end cap region operable at a third temperature.

1 . A method comprising:
 transferring a plurality of substrates into a furnace, the furnace comprising a processing region and at least one end cap region disengageably coupled to the processing region, wherein each of the plurality of substrates includes a copper and indium composite structure;   introducing a gaseous species including a hydrogen species and a selenide species into the furnace;   transferring thermal energy into the furnace to increase a temperature of the furnace from a first temperature to a second temperature;   initiating formation of a copper indium diselenide film from the copper and indium composite structure;   decomposing residual selenide species from an inner region of the processing region;   changing the temperature of the furnace from the second temperature to a third temperature;   depositing elemental selenium species within a vicinity of the at least one end cap region;   changing the temperature of the furnace from the third temperature to the first temperature; and   removing the remaining gaseous species from the chamber.   
     
     
         2 . A method comprising:
 transferring a plurality of substrates into a furnace, wherein each of the plurality of substrates includes a copper and indium composite structure;   introducing a gaseous species including a hydrogen species and a selenide species into the furnace;   transferring thermal energy into the furnace to increase a temperature of the furnace from a first temperature to a second temperature;   initiating formation of a copper indium diselenide film from the copper and indium composite structure;   decomposing residual selenide species from an inner region of the processing region;   changing the temperature of the furnace from the second temperature to a third temperature;   depositing elemental selenium species within a vicinity of a end-cap region of the furnace;   changing the temperature of the furnace from the third temperature to the first temperature; and   removing the remaining gaseous species from the chamber.   
     
     
         3 . A system comprising:
 a process chamber having an inner process region;   an end cap coupled to the process chamber and including an end cap region; and   one or more heating elements coupled to the process chamber;   wherein the system is configured to:
 hold a plurality of substrates in the process chamber, each of the plurality of substrates including a copper and indium composite structure; 
 introduce a gaseous species including a hydrogen species and a selenide species into the process chamber; 
 heat the process chamber from a first temperature to a second temperature using the one or more heating elements; 
 initiate formation of a copper indium diselenide film from the copper and indium composite structure; 
 cause decomposition of residual selenide species from the inner process region; 
 change the temperature of the process chamber from the second temperature to a third temperature; 
 deposit elemental selenium species within a vicinity of the end cap region; 
 cause formation of copper indium diselenide film over each of the plurality of substrates; and 
 remove remaining gaseous species from the process chamber not used in the formation of the copper indium diselenide film. 
   
     
     
         4 . The system of  claim 3  further comprising a gas injection pipe configured to introduce the gaseous species into the process chamber. 
     
     
         5 . The system of  claim 3  wherein the end cap is disengageably coupled to the process chamber. 
     
     
         6 . The system of  claim 3  wherein the remaining gaseous species are removed from the process chamber using a turbomolecular pump. 
     
     
         7 . The system of  claim 3  wherein the end cap comprises metal. 
     
     
         8 . The system of  claim 3  wherein the process chamber comprises a quartz tube. 
     
     
         9 . The system of  claim 3  wherein the process chamber is characterized by a first specific heat value and the end cap is characterized by a second specific heat value, wherein the second specific value is lower than the first specific heat value. 
     
     
         10 . The system of  claim 3  wherein the second temperature ranges between 350° C. and 450° C. 
     
     
         11 . The system of  claim 3  wherein the third temperature ranges between 500° C. and 525° C. 
     
     
         12 . The system of  claim 3  wherein the end cap is characterized by a first thermal conductivity and the process chamber is characterized by a second thermal conductivity and wherein the first thermal conductivity is lower than the second thermal conductivity. 
     
     
         13 . The system of  claim 12  further configured to cause creation of convection current within the inner process region. 
     
     
         14 . The system of  claim 3  wherein the one or more heating elements are individually controllable. 
     
     
         15 . The system of  claim 3  further configured to:
 decompose residual selenide species from the inner region of the process chamber; and 
 remove a first portion of selenium from the copper indium diselenide film and replace it with a second portion of sulfur. 
 
     
     
         16 . The system of  claim 15  wherein the first portion and the second portion are about 5% each. 
     
     
         17 . The system of  claim 3  further comprising a baffle disposed between the inner region of the process chamber and the end cap. 
     
     
         18 . The system of  claim 3  wherein the plurality of substrates are held in a vertical orientation with respect to gravity. 
     
     
         19 . The system of  claim 3  wherein the end cap is configured to be separable from the process chamber to allow mechanical cleaning of the end cap. 
     
     
         20 . The system of  claim 3  wherein the process chamber is characterized by a pressure of about 650 Torr.