Fabrication of large grain polycrystalline silicon film by nano aluminum-induced crystallization of amorphous silicon

Abstract

One aspect of the present invention relates to a method for fabricating a polycrystalline silicon film. In one embodiment, the method includes the steps of providing a substrate having a thermally-grown silicon dioxide layer, forming an amorphous silicon film on the thermally-grown silicon dioxide layer of the substrate, forming an aluminum layer on the amorphous silicon film to form a structure having the substrate, the amorphous silicon film and the aluminum layer, and annealing the structure at an annealing temperature for a period of time in an N 2 environment with a ramp-up time to crystallize the amorphous silicon film to form a polycrystalline silicon film.

1 - 50 . (canceled) 
     
     
         51 . An apparatus for fabricating a polycrystalline film, comprising:
 a low-pressure chemical vapor deposition (LPCVD) system configured to form an amorphous silicon film on a substrate;   a system configured to form an aluminum layer such as to form a structure having the substrate, the amorphous silicon film, and the aluminum layer; and   an annealing means configured to anneal the structure at an annealing temperature effective for a period of time with an annealing temperature ramp-up time to crystallize the amorphous silicon film to form a polycrystalline silicon film.   
     
     
         52 . The apparatus of  claim 51 , wherein the aluminum layer is formed on the amorphous silicon film. 
     
     
         53 . The apparatus of  claim 51 , wherein the annealing means is further configured to anneal the structure in a nitrogen environment. 
     
     
         54 . The apparatus of  claim 51 , wherein the annealing temperature ramp-up time is at least 10 minutes, and wherein the polycrystalline silicon film comprises a plurality of crystallites and the average crystallite size of the plurality of crystallites increases with the annealing temperature ramp-up time. 
     
     
         55 . The apparatus of  claim 51 , wherein the aluminum layer has a thickness in a range of about 5-100 nm. 
     
     
         56 . The apparatus of  claim 51 , wherein the amorphous silicon film has a thickness in a range of about 50-200 nm. 
     
     
         57 . The apparatus of  claim 51 , wherein the substrate comprises a thermally-grown silicon dioxide layer. 
     
     
         58 . The apparatus of  claim 57 , wherein the silicon dioxide layer is adapted for preventing the crystal orientation of the substrate from affecting the crystallization of the amorphous silicon film, and has a thickness in a range of about 1-3 μm. 
     
     
         59 . The apparatus of  claim 51 , wherein the aluminum layer has a thickness in a range of about 5-100 nm. 
     
     
         60 . The apparatus of  claim 51 , wherein the aluminum layer is formed uniformly such that the thickness of the aluminum layer is substantially constant or is formed variable over the aluminum layer with a desired pattern. 
     
     
         61 . The apparatus of  claim 51 , wherein the polycrystalline silicon film comprises a plurality of crystallites and the average size of the plurality of crystallites increases with the annealing temperature ramp-up time. 
     
     
         62 . The apparatus of  claim 51 , wherein the annealing temperature is in a range of about 50-450° C. 
     
     
         63 . An apparatus for fabricating a polycrystalline film, comprising:
 a plasma-enhanced chemical vapor deposition (PECVD) system configured to form an amorphous silicon film on a substrate;   a layer forming means for forming an aluminum layer such as to form a structure having the substrate, the amorphous silicon film, and the aluminum layer; and   an annealing means for annealing the structure at an annealing temperature effective for a period of time with an annealing temperature ramp-up time to crystallize the amorphous silicon film to form a polycrystalline silicon film.   
     
     
         64 . The apparatus of  claim 63 , wherein the aluminum layer is formed on the amorphous silicon film. 
     
     
         65 . The apparatus of  claim 63 , wherein the annealing temperature ramp-up time is at least 10 minutes, and wherein the polycrystalline silicon film comprises a plurality of crystallites and the average crystallite size of the plurality of crystallites increases with the annealing temperature ramp-up time. 
     
     
         66 . The apparatus of  claim 63 , wherein the aluminum layer has a thickness in a range of about 5-100 nm. 
     
     
         67 . The apparatus of  claim 63 , wherein the PECVD system is configured such that the RF power is about 15 W. 
     
     
         68 . The apparatus of  claim 63 , wherein the PECVD system is configured such that the chamber pressure is about 0.5 Torr. 
     
     
         69 . The apparatus of  claim 63 , wherein the PECVD system is configured such that the substrate temperature is about 250° C. 
     
     
         70 . The apparatus of  claim 63 , wherein the PECVD system is configured such that the silane flow rate is about 85 sccm. 
     
     
         71 . The apparatus of  claim 63 , wherein the substrate comprises a silicon wafer. 
     
     
         72 . The apparatus of  claim 63 , wherein the amorphous silicon film has a thickness in a range of about 50-200 nm. 
     
     
         73 . The apparatus of  claim 63 , wherein the substrate comprises a thermally-grown silicon dioxide layer adapted for preventing the crystal orientation of the substrate from affecting the crystallization of the amorphous silicon film. 
     
     
         74 . The apparatus of  claim 73 , wherein the silicon dioxide layer has a thickness in a range of about 1-3 μm. 
     
     
         75 . The apparatus of  claim 63 , wherein the aluminum layer has a thickness in a range of about 5-100 nm. 
     
     
         76 . The apparatus of  claim 63 , wherein the aluminum layer is formed uniformly such that the thickness of the aluminum layer is substantially constant or is formed variable over the aluminum layer with a desired pattern. 
     
     
         77 . The apparatus of  claim 63 , wherein the polycrystalline silicon film comprises a plurality of crystallites and the average size of the plurality of crystallites increases with the annealing temperature ramp-up time. 
     
     
         78 . The apparatus of  claim 63 , wherein the annealing temperature is in a range of about 50-450° C. 
     
     
         79 . The apparatus of  claim 62 , wherein the annealing means is further configured to anneal the structure in a nitrogen environment. 
     
     
         80 . A means for fabricating a polycrystalline film, comprising:
 a film forming means for forming an amorphous silicon film on a substrate;   a layer forming means for forming an aluminum layer such as to form a structure having the substrate, the amorphous silicon film, and the aluminum layer; and   an annealing means for annealing the structure at an annealing temperature effective for a period of time with an annealing temperature ramp-up time to crystallize the amorphous silicon film to form a polycrystalline silicon film.   
     
     
         81 . The means of  claim 80 , wherein the aluminum layer is formed on the amorphous silicon film. 
     
     
         82 . The means of  claim 80 , wherein the substrate comprises a thermally-grown silicon dioxide layer. 
     
     
         83 . The means of  claim 82 , wherein, as formed, the silicon dioxide layer has a thickness in a range of about 1-3 μm and is adapted to prevent the crystal orientation of the substrate from affecting the crystallization of the amorphous silicon film. 
     
     
         84 . The means of  claim 80 , wherein, as formed, the aluminum layer has a thickness in a range of about 5-100 nm. 
     
     
         85 . The means of  claim 80 , wherein, as formed, the amorphous silicon film has a thickness in a range of about 50-200 nm. 
     
     
         86 . The means of  claim 80 , wherein, as formed, the polycrystalline silicon film comprises a plurality of crystallites and the average crystallite size of the plurality of crystallites increases with the annealing temperature ramp-up time. 
     
     
         87 . The means of  claim 80 , wherein the annealing temperature ramp-up time is at least 10 minutes. 
     
     
         88 . The means of  claim 80 , wherein the annealing temperature is in a range of about 50-450° C. 
     
     
         89 . The means of  claim 80 , wherein the substrate comprises a silicon wafer. 
     
     
         90 . The means of  claim 80 , wherein the layer forming means is different from the film forming means. 
     
     
         91 . The means of  claim 80 , wherein the film forming means comprises a plasma-enhanced chemical vapor deposition (PECVD) system. 
     
     
         92 . The means of  claim 80 , wherein the layer forming means comprises a thermal evaporator. 
     
     
         93 . The means of  claim 80 , wherein at least one of the film forming means and the layer forming means comprises a sputtering system. 
     
     
         94 . The means of  claim 80 , wherein the layer forming means comprises a metal evaporator. 
     
     
         95 . The means of  claim 80 , wherein the film forming means comprises a low-pressure chemical vapor deposition (LPCVD) system. 
     
     
         96 . A means for fabricating a polycrystalline film, comprising:
 a film forming means for forming an amorphous silicon film on a substrate;   a layer forming means for forming an aluminum layer such as to form a structure having the substrate, the amorphous silicon film, and the aluminum layer, wherein, as formed, the aluminum layer has a thickness in a range of about 5-100 nm; and   an annealing means for annealing the structure at an annealing temperature in a range of about 50-450° C. effective for a period of time with an annealing temperature ramp-up time of at least 10 minutes to crystallize the amorphous silicon film to form a polycrystalline silicon film.   
     
     
         97 . The means of  claim 96 , wherein the aluminum layer is formed on the amorphous silicon film. 
     
     
         98 . The means of  claim 96 , wherein the layer forming means is different from the film forming means. 
     
     
         99 . The means of  claim 96 , wherein the film forming means comprises a plasma-enhanced chemical vapor deposition (PECVD) system. 
     
     
         100 . The means of  claim 96 , wherein the layer forming means comprises a thermal evaporator. 
     
     
         101 . The means of  claim 96 , wherein at least one of the film forming means and layer forming means comprises a sputtering system. 
     
     
         102 . The means of  claim 96 , wherein the layer forming means comprises a metal evaporator. 
     
     
         103 . The means of  claim 96 , wherein the structure is annealed in a nitrogen environment. 
     
     
         104 . The means of  claim 96 , wherein the film forming means comprises a low-pressure chemical vapor deposition (LPCVD) system. 
     
     
         105 . The means of  claim 96 , wherein the substrate comprises a thermally-grown silicon dioxide layer which, as formed, comprises a thickness in a range of about 1-3 μm and is adapted to prevent the crystal orientation of the substrate from affecting the crystallization of the amorphous silicon film having a thermally-grown silicon dioxide layer.