Production apparatus of semiconductor layer employing DC bias and VHF power

Abstract

The invention provides a process for producing a semiconductor layer by introducing a raw gas into a discharge chamber and supplying high-frequency power to the chamber to decompose the raw gas by discharge, thereby forming a semiconductor layer on a substrate within the discharge chamber, the process comprising the steps of supplying high-frequency power of at least very high frequency (VHF) as the high-frequency power; supplying bias power of direct current power and/or high-frequency power of radio-frequency (RF) together with the high-frequency power of VHF to the discharge chamber; and controlling a direct current component of an electric current flowing into an electrode, to which the bias power is supplied, so as to fall within a range of from 0.1 A/m 2 to 10 A/m 2 in terms of a current density based on the area of an inner wall of the discharge chamber. A good-quality semiconductor layer can be deposited over a large area at a high speed.

What is claimed is:  
     
         1 . A process for producing a semiconductor layer by introducing a raw gas into a discharge chamber and supplying high-frequency power to the chamber to decompose the raw gas by discharge, thereby forming a semiconductor layer on a substrate within the discharge chamber, the process comprising the steps of: 
 supplying high-frequency power of at least very high frequency (VHF) as the high-frequency power;    supplying bias power of direct current power and/or high-frequency power of radio-frequency (RF) together with the high-frequency power of VHF to the discharge chamber; and    controlling a direct current component of an electric current flowing into an electrode, to which the bias power is supplied, so as to fall within a range of from 0.1 A/m 2  to 10 A/m 2  in terms of a current density based on the area of an inner wall of the discharge chamber.    
     
     
         2 . The process according to  claim 1 , wherein the electric potential of the electrode, to which the bias power is supplied, is controlled to the same level as that of the substrate or positive potential against the substrate.  
     
     
         3 . The process according to  claim 2 , wherein a potential difference between the electrode, to which the bias power is supplied, and the substrate is controlled within a range of from 0 to 500 V.  
     
     
         4 . The process according to  claim 1 , wherein a raw gas comprising a silicon atom-containing molecule is used as the raw gas to form a silicon type non-monocrystalline semiconductor layer on the substrate.  
     
     
         5 . The process according to  claim 1 , wherein the substrate and the inner wall surface of the discharge chamber are controlled to earth potential.  
     
     
         6 . The process according to  claim 1 , wherein the bias power is supplied to an electrode provided independently of the electrode to which the high-frequency power of VHF is supplied,  
     
     
         7 . The process according to  claim 1 , wherein the bias power is supplied to the electrode to which the high-frequency power of VHF is supplied.  
     
     
         8 . The process according to  claim 1 , wherein direct current power is used as the bias power.  
     
     
         9 . The process according to  claim 1 , wherein the semiconductor layer is formed in accordance with a plasma CVD method.  
     
     
         10 . The process according to  claim 1 , wherein a band-like substrate is used as the substrate.  
     
     
         11 . The process according to  claim 1 , wherein a conductive substrate is used as the substrate.  
     
     
         12 . The process according to  claim 1 , wherein the substrate is used as a part of the inner wall of the discharge chamber.  
     
     
         13 . A process for producing a semiconductor layer by introducing a raw gas into a plurality of discharge chambers, supplying high-frequency power to the chambers to decompose the raw gas by discharge, and causing a substrate to successively pass through the discharge chambers, thereby forming a plurality of semiconductor layers on the substrate, the process comprising the steps of: 
 supplying high-frequency power of very high frequency (VHF) as the high-frequency power to two or more discharge chambers of the plural discharge chambers;    supplying bias power of different levels from each other to the discharge chambers, to which the high-frequency power of VHF is supplied, according to respective film-forming conditions in the discharge chambers; and    controlling the electric potential of each electrode, to which the bias power is supplied, to the same level as that of the substrate or positive potential against the substrate.    
     
     
         14 . The process according to  claim 13 , wherein a direct current component of an electric current flowing into each electrode, to which the bias power is supplied, is controlled so as to fall within a range of from 0.1 A/m 2  to 10 A/m 2  in terms of a current density based on the area of an inner wall of the discharge chamber.  
     
     
         15 . The process according to  claim 13 , wherein a potential difference between each electrode, to which the bias power is supplied, and the substrate is controlled within a range of from 0 to 500 V.  
     
     
         16 . The process according to  claim 13 , wherein a raw gas comprising a silicon atom-containing molecule is used as the raw gas to form a silicon type non-monocrystalline semiconductor layer on the substrate.  
     
     
         17 . The process according to  claim 13 , wherein the substrate and the inner wall surfaces of the discharge chambers are controlled to earth potential.  
     
     
         18 . The process according to  claim 13 , wherein the bias power is supplied to an electrode provided independently of the electrode to which the high-frequency power of VHF is supplied,  
     
     
         19 . The process according to  claim 13 , wherein the bias power is supplied to the electrode to which the high-frequency power of VHF is supplied.  
     
     
         20 . The process according to  claim 13 , wherein direct current power is used as the bias power.  
     
     
         21 . The process according to  claim 13 , wherein the semiconductor layer is formed in accordance with a plasma CVD process.  
     
     
         22 . The process according to  claim 13 , wherein a band-like substrate is used as the substrate.  
     
     
         23 . The process according to  claim 13 , wherein a conductive substrate is used as the substrate.  
     
     
         24 . The process according to  claim 13 , wherein the substrate is used as a part of the inner wall of the discharge chamber.  
     
     
         25 . A process for fabricating a photovoltaic cell, comprising the steps of introducing a raw gas into a discharge chamber and supplying high-frequency power to the chamber to decompose the raw gas by discharge, thereby forming an i-type semiconductor layer on a substrate within the discharge chamber, the process comprising the steps of: 
 supplying high-frequency power of at least very high frequency (VHF) as the high-frequency power in the step of forming the i-type semiconductor layer;    supplying bias power of direct current power and/or high-frequency power of radio-frequency (RF) together with the high-frequency power of VHF to the discharge chamber; and    controlling a direct current component of an electric current flowing into an electrode, to which the bias power is supplied, so as to fall within a range of from 0.1 A/m 2  to 10 A/m 2  in terms of a current density based on the area of an inner wall of the discharge chamber.    
     
     
         26 . The process according to  claim 25 , wherein the electric potential of the electrode, to which the bias power is supplied, is controlled to the same level as that of the substrate or positive potential against the substrate.  
     
     
         27 . The process according to  claim 26 , wherein a potential difference between the electrode, to which the bias power is supplied, and the substrate is controlled within a range of from 0 to 500 V.  
     
     
         28 . The process according to  claim 25 , wherein a raw gas comprising a silicon atom-containing molecule is used as the raw gas to form a silicon type non-monocrystalline semiconductor layer on the substrate.  
     
     
         29 . The process according to  claim 25 , wherein the substrate and the inner wall surface of the discharge chamber are controlled to earth potential.  
     
     
         30 . The process according to  claim 25 , wherein the bias power is supplied to an electrode provided independently of the electrode to which the high-frequency power of VHF is supplied,  
     
     
         31 . The process according to  claim 25 , wherein the bias power is supplied to the electrode to which the high-frequency power of VHF is supplied.  
     
     
         32 . The process according to  claim 25 , wherein direct current power is used as the bias power.  
     
     
         33 . The process according to  claim 25 , wherein the i-type semiconductor layer is formed in accordance with a plasma CVD process.  
     
     
         34 . The process according to  claim 25 , wherein a band-like substrate is used as the substrate.  
     
     
         35 . The process according to  claim 25 , wherein a conductive substrate is used as the substrate.  
     
     
         36 . The process according to  claim 25 , wherein the substrate is used as a part of the inner wall of the discharge chamber.  
     
     
         37 . The process according to  claim 25 , which further comprises the step of forming an n-type semiconductor layer and the step of forming a p-type semiconductor layer, respectively, before and after the step of forming the i-type semiconductor layer.  
     
     
         38 . A process for fabricating a photovoltaic cell by introducing a raw gas into a plurality of discharge chambers, supplying high-frequency power to the chambers to decompose the raw gas by discharge, and causing a substrate to successively pass through the discharge chambers, thereby at least forming a plurality of i-type semiconductor layers on the substrate, the process comprising the steps of: 
 supplying high-frequency power of very high frequency (VHF) as the high-frequency power to two or more discharge chambers of the plural discharge chambers in which the respective i-type semiconductor layers are formed;    supplying bias power of different levels from each other to the discharge chambers, to which the high-frequency power of VHF is supplied, according to respective film-forming conditions in the discharge chambers; and    controlling the electric potential of each electrode, to which the bias power is supplied, to the same level as that of the substrate or positive potential against the substrate.    
     
     
         39 . The process according to  claim 38 , wherein a direct current component of an electric current flowing into each electrode, to which the bias power is supplied, is controlled so as to fall within a range of from 0.1 A/m 2  to 10 A/m 2  in terms of a current density based on the area of an inner wall of the discharge chamber.  
     
     
         40 . The process according to  claim 38 , wherein a potential difference between each electrode, to which the bias power is supplied, and the substrate is controlled within a range of from 0 to 500 V.  
     
     
         41 . The process according to  claim 38 , wherein a raw gas comprising a silicon atom-containing molecule is used as the raw gas to form a silicon type non-monocrystalline semiconductor layer on the substrate.  
     
     
         42 . The process according to  claim 38 , wherein the substrate and the inner wall surfaces of the discharge chambers are controlled to earth potential.  
     
     
         43 . The process according to  claim 38 , wherein the bias power is supplied to an electrode provided independently of the electrode to which the high-frequency power of VHF is supplied,  
     
     
         44 . The process according to  claim 38 , wherein the bias power is supplied to the electrode to which the high-frequency power of VHF is supplied.  
     
     
         45 . The process according to  claim 38 , wherein direct current power is used as the bias power.  
     
     
         46 . The process according to  claim 38 , wherein all the i-type semiconductor layers are formed in accordance with a plasma CVD process.  
     
     
         47 . The process according to  claim 38 , wherein a band-like substrate is used as the substrate.  
     
     
         48 . The process according to  claim 38 , wherein a conductive substrate is used as the substrate.  
     
     
         49 . The process according to  claim 38 , wherein the substrate is used as a part of the inner wall of the discharge chamber.  
     
     
         50 . The process according to  claim 38 , which further comprises the step of forming an n-type semiconductor layer and the step of forming a p-type semiconductor layer, respectively, before and after the respective steps of forming the plural i-type semiconductor layers.  
     
     
         51 . An apparatus for producing a semiconductor layer by introducing a raw gas into a discharge chamber and supplying high-frequency power to the chamber to decompose the raw gas by discharge, thereby forming a semiconductor layer on a substrate within the discharge chamber, the apparatus comprising: 
 a means for supplying high-frequency power of at least very high frequency (VHF) as the high-frequency power;    a means for supplying bias power of direct current power and/or high-frequency power of radio-frequency (RF) together with the high-frequency power of VHF to the discharge chamber; and    a means for controlling a direct current component of an electric current flowing into an electrode, to which the bias power is supplied, so as to fall within a range of from 0.1 A/m 2  to 10 A/m 2  in terms of a current density based on the area of an inner wall of the discharge chamber.    
     
     
         52 . The apparatus according to  claim 51 , wherein the means for supplying the high-frequency power of VHF comprises a discharge electrode and a high-frequency power source of VHF connected to the discharge electrode.  
     
     
         53 . The apparatus according to  claim 52 , wherein the means for supplying the bias power comprises a bias electrode provided separately from the discharge electrode and a power source connected to the bias electrode.  
     
     
         54 . The apparatus according to  claim 52 , wherein the means for supplying the bias power comprises a power source connected to the discharge electrode.  
     
     
         55 . The apparatus according to  claim 52 , wherein the means for supplying the bias power comprises a direct current power source connected to the discharge electrode through a high-frequency power blocking means.  
     
     
         56 . The apparatus according to  claim 55 , wherein the high-frequency power blocking means is a choke coil.  
     
     
         57 . The apparatus according to  claim 55 , wherein the high-frequency power source is connected to the discharge electrode through a direct current power blocking means.  
     
     
         58 . The apparatus according to  claim 57 , wherein the direct current power blocking means is a capacitor.  
     
     
         59 . The apparatus according to  claim 51 , wherein the substrate and the inner wall surface of the discharge chamber are at earth potential.  
     
     
         60 . The apparatus according to  claim 51 , wherein the substrate is used as a part of the inner wall of the discharge chamber.  
     
     
         61 . An apparatus for producing a semiconductor layer by introducing a raw gas into a plurality of discharge chambers, supplying high-frequency power to the chambers to decompose the raw gas by discharge, and causing a substrate to successively pass through the discharge chambers, thereby forming a plurality of semiconductor layers on the substrate, the apparatus comprising: 
 a means for supplying high-frequency power of very high frequency (VHF) as the high-frequency power to two or more discharge chambers of the plural discharge chambers;    a means for supplying bias power of different levels from each other to the discharge chambers, to which the high-frequency power of VHF is supplied, according to respective film-forming conditions in the discharge chambers; and    a means for controlling the electric potential of each electrode, to which the bias power is supplied, to the same level as that of the substrate or positive potential against the substrate.    
     
     
         62 . The apparatus according to  claim 61 , wherein the means for supplying the high-frequency power of VHF comprises a discharge electrode and a high-frequency power source of VHF connected to the discharge electrode.  
     
     
         63 . The apparatus according to  claim 62 , wherein the means for supplying the bias power comprises a bias electrode provided separately from the discharge electrode and a power source connected to the bias electrode.  
     
     
         64 . The apparatus according to  claim 62 , wherein the means for supplying the bias power comprises a power source connected to the discharge electrode.  
     
     
         65 . The apparatus according to  claim 62 , wherein the means for supplying the bias power comprises a direct current power source connected to the discharge electrode through a high-frequency power blocking means.  
     
     
         66 . The apparatus according to  claim 65 , wherein the high-frequency power blocking means is a choke coil.  
     
     
         67 . The apparatus according to  claim 65 , wherein the high-frequency power source is connected to the discharge electrode through a direct current power blocking means.  
     
     
         68 . The apparatus according to  claim 67 , wherein the direct current power blocking means is a capacitor.  
     
     
         69 . The apparatus according to  claim 61 , wherein the substrate and the inner wall surface of the discharge chamber are at earth potential.  
     
     
         70 . The apparatus according to  claim 61 , wherein the substrate is used as a part of the inner wall of the discharge chamber.