Apparatus and method for film formation

Abstract

An apparatus and method for forming a thin film on a substrate by RPCVD which provides for very low levels of carbon and oxygen impurities and includes the steps of introducing a Group VA plasma into a first deposition zone of a growth chamber, introducing a Group IIIA reagent into a second deposition zone of the growth chamber which is separate from the first deposition zone and introducing an amount of an additional reagent selected from the group consisting of ammonia, hydrazine, di-methyl hydrazine and a hydrogen plasma through an additional reagent inlet into the second deposition zone such that the additional reagent and the Group IIIA reagent mix prior to deposition.

1 . An RPCVD apparatus for forming a film, the apparatus including a growth chamber comprising:
 (a) a Group VA plasma inlet located in a first deposition zone of the growth chamber to introduce a Group VA plasma thereto;   (b) a Group IIIA reagent inlet located in a second deposition zone of the growth chamber to introduce a Group IIIA reagent thereto;   (c) an additional reagent inlet adjacent the Group IIIA reagent inlet to introduce an additional reagent selected from the group consisting of ammonia, hydrazine, di-methyl hydrazine and hydrogen plasma into the second deposition zone such that the additional reagent and Group IIIA reagent mix prior to deposition; and   (d) a substrate holder adapted to support one or more substrates and rotate each substrate between the first and second deposition zones.   
     
     
         2 . The apparatus of  claim 1  wherein the additional reagent inlet is an ammonia inlet. 
     
     
         3 . The apparatus of  claim 1  or  claim 2  wherein the first deposition zone is substantially isolated from the second deposition zone 
     
     
         4 . The apparatus of any one of the preceding claims wherein the Group VA plasma inlet and/or the Group IIIA reagent inlet open into the growth chamber at a distance between about 1 cm to about 30 cm from a growth surface of the one or more substrates. 
     
     
         5 . The apparatus of  claim 4  wherein the Group IIIA reagent inlet opens into the growth chamber at a distance between about 1 cm to about 10 cm from a growth surface of the one or more substrates. 
     
     
         6 . The apparatus of  claim 1  wherein at least one of the Group VA plasma inlet or the Group IIIA reagent inlet end flush with a ceiling of the growth chamber which is located between about 1 to about 30 cm vertically above a growth surface of the one or more substrates. 
     
     
         7 . The apparatus of  claim 6  wherein the ceiling is located between about 15 to 30 cm vertically above a growth surface of the one or more substrates. 
     
     
         8 . The apparatus of any one of the preceding claims wherein the additional reagent inlet opens into the growth chamber substantially adjacent to the opening of the Group IIIA reagent inlet to promote mixing of said reagents prior to their contacting the one or more substrates. 
     
     
         9 . The apparatus of any one of the preceding claims wherein the growth chamber comprises one or more structures associated with the additional reagent inlet and/or the Group IIIA reagent inlet to promote mixing of said reagents immediately prior to their contacting the one or more substrates. 
     
     
         10 . The apparatus of any one of the preceding claims wherein there is a direct flow path between the Group VA plasma inlet and the one or more substrates. 
     
     
         11 . The apparatus of  claim 10  wherein the direct flow path between the Group VA plasma inlet and the one or more substrates extends to an unimpeded path between a plasma generator for generating the Group VA plasma and the one or more substrates. 
     
     
         12 . The apparatus of  claim 1  wherein an opening of the additional reagent inlet opens into the growth chamber in close proximity to the one or more substrates. 
     
     
         13 . The apparatus of  claim 12  wherein the additional reagent inlet opens into the growth chamber at a distance between about 1 cm to about 10 cm from a growth surface of the one or more substrates. 
     
     
         14 . The apparatus of  claim 12  wherein the additional reagent inlet extends downwardly from the ceiling of the growth chamber to end in close proximity to a growth surface of the one or more substrates. 
     
     
         15 . The apparatus of  claim 12  wherein the additional reagent inlet opens into the growth chamber through a side wall thereof at a height suitable to enable a flow of additional reagent entering therethrough to have a flow path passing over and substantially adjacent to a growth surface of the one or more substrates. 
     
     
         16 . The apparatus of any one of the preceding claims wherein the Group VA plasma inlet and the Group IIIA reagent inlet are located centrally within the growth chamber. 
     
     
         17 . The apparatus of  claim 16  wherein at least one of the Group VA plasma inlet and the Group IIIA reagent inlet is provided with a flow control device to direct the corresponding plasma or reagent into the appropriate first or second deposition zone. 
     
     
         18 . The apparatus of any one of  claim 1  to  claim 15  wherein the Group VA plasma inlet and the Group IIIA reagent inlet are located peripherally within the growth chamber. 
     
     
         19 . The apparatus of  claim 18  wherein the Group VA plasma inlet and the Group IIIA reagent inlet are located substantially at opposite ends of the growth chamber. 
     
     
         20 . The apparatus of any one of the preceding claims wherein rotation of the substrate holder causes the one or more substrates to pass sequentially from the first deposition zone to the second deposition zone. 
     
     
         21 . The apparatus of any one of the preceding claims further comprising one or more heating devices to heat the additional reagent inlet and/or the Group IIIA reagent inlet prior to the respective reagents entering the growth chamber. 
     
     
         22 . A method of forming a thin film on a substrate by RPCVD including the steps of:
 (a) introducing a Group VA plasma through a Group VA plasma inlet into a first deposition zone of a growth chamber;   (b) introducing a Group IIIA reagent through a Group IIIA reagent inlet into a second deposition zone of the growth chamber, the second deposition zone being substantially isolated from the first deposition zone;   (c) introducing an additional reagent selected from the group consisting of ammonia, hydrazine, di-methyl hydrazine and hydrogen plasma through an additional reagent inlet into the second, deposition zone such that the additional reagent and the Group IIIA reagent mix prior to deposition; and   (d) moving the substrate between the first and second deposition zones,   to thereby form a thin film on the substrate.   
     
     
         23 . The method of  claim 22  wherein the additional reagent is ammonia. 
     
     
         24 . The method of  claim 22  or  23  wherein the additional reagent is introduced into the second deposition zone substantially adjacent the opening of the Group IIIA inlet. 
     
     
         25 . The method of any one of  claim 22  to  claim 24  additional reagent and the Group IIIA reagent are preferably being introduced into the growth chamber simultaneously 
     
     
         26 . The method of any one of  claim 22  to  claim 25  wherein the Group IIIA reagent is a Group IIIA metal organic reagent. 
     
     
         27 . The method of  claim 26  wherein the Group IIIA metal organic reagent is a Group IIIA metal alkyl reagent. 
     
     
         28 . The method of  claim 27  wherein the Group IIIA metal alkyl reagent is selected from the group consisting of trimethylgallium, triethylgallium, trimethylindium and trimethylaluminium. 
     
     
         29 . The method of any one of  claim 22  to  claim 28  wherein the Group VA plasma is a nitrogen plasma comprising active nitrogen species. 
     
     
         30 . The method of any one of  claim 22  to  claim 29  further including the step of promoting the mixing of the Group IIIA reagent and the additional reagent adjacent the one or more substrates. 
     
     
         31 . The method of any one of  claim 22  to  claim 30  wherein the additional reagent flow rate is between 15 to 1500 sccm. 
     
     
         32 . The method of  claim 31  wherein the additional reagent flow rate is between 30 to 1000 sccm. 
     
     
         33 . The method of any one of  claim 22  to  claim 31  further including the step of controlling the power of the plasma generator to be between about 500 to about 4000 W. 
     
     
         34 . The method of  claim 33  wherein the power of the plasma generator is between about 500 to about 3000 W. 
     
     
         35 . The method of any one of  claim 22  to  claim 34  wherein the growth pressure in the growth chamber is between 2-5 torr. 
     
     
         36 . The method of any one of  claim 22  to  claim 35  wherein the plasma flow is between 2000-3000 sccm. 
     
     
         37 . The method of any one of  claim 22  to  claim 36  further including the step of controlling the temperature in the growth chamber to be between about 400 to about 1200° C. 
     
     
         38 . The method of  claim 37  wherein the temperature in the growth chamber is between about 500 to about 1000° C. 
     
     
         39 . The method of  claim 38  wherein the temperature in the growth chamber is between about 500 to about 800° C. 
     
     
         40 . The method of any one of  claim 22  to  claim 39  further including the step of isolating the deposition zones to prevent the mixing of the Group VA plasma and Group IIIA reagent. 
     
     
         41 . The method of any one of  claim 22  to  claim 40  further including the step of controlling the flow of one or more of the Group VA plasma or Group IIIA reagent upon exiting the associated inlet to direct that flow to a desired deposition zone. 
     
     
         42 . The method of any one of  claim 22  to  claim 41  wherein the additional reagent is introduced into the growth chamber through a side wall thereof. 
     
     
         43 . The method of any one of  claim 22  to  claim 42  wherein the additional reagent is introduced into the growth chamber to form a substantially horizontal flow path passing over and substantially adjacent to a growth surface of the substrate. 
     
     
         44 . The method of any one of  claims 22  to  43  claim further including the step of heating one or more of the reagents prior to their entering the growth chamber. 
     
     
         45 . The method of any one of  claims 22  to  44  further include a step of p-type doping of the growing film. 
     
     
         46 . A method of forming a thin film having a carbon impurity content of less than about 5E+17 atom/cm 3 , on a substrate by RPCVD including the steps of:
 (a) introducing a Group VA plasma through a Group VA plasma inlet into a first deposition zone of a growth chamber wherein a direct flow path is provided between the Group VA plasma inlet and a substrate located in the first deposition zone;   (b) introducing a Group IIIA reagent through a Group IIIA reagent inlet into a second deposition zone of the growth chamber, the second deposition zone being substantially isolated from the first deposition zone;   (c) introducing an additional reagent selected from the group consisting of ammonia, hydrazine, di-methyl hydrazine and hydrogen plasma through an additional reagent inlet into the second deposition zone such that the additional reagent and the Group IIIA reagent mix prior to deposition;   (d) moving the substrate between the first and second deposition zones,   
       to thereby form a thin film on the substrate having a carbon impurity content of less than about 5E+17 atom/cm 3 . 
     
     
         47 . The method of  claim 46  wherein the carbon impurity content is less than about 3E+17 atom/cm 3 . 
     
     
         48 . The method of  claim 47  wherein the carbon impurity content is less than about 2E+17 atom/cm 3 . 
     
     
         49 . The method of  claim 48  wherein the carbon impurity content is less than or about 1E+17 atom/cm 3 . 
     
     
         50 . The method of  claim 46  wherein the oxygen impurity content of the thin film is less than about 6E+17 atom/cm 3 . 
     
     
         51 . The method of  claim 50  wherein the oxygen impurity content is less than about 2E+17 atom/cm 3 . 
     
     
         52 . A film formed by the method of any one of  claim 22  to  claim 51 . 
     
     
         53 . Use of the film of  claim 52  in a semiconductor device.