System and method for fabricating photovoltaic cells

Abstract

A substrate processing system includes a source unit configured to supply a deposition material to a substrate, a substrate holder configured to hold a substrate to receive the deposition material, a shadow mask comprising a frame that includes two opposing arms; and a crossbar configured to be mounted to the two opposing arms. The frame and the crossbar define a plurality of openings that allow the deposition material supplied by the source unit to be deposited on the substrate. A transport mechanism can produce relative movement between the shadow mask and the substrate.

1 . An apparatus for fabricating photovoltaic-cell modules, comprising:
 a chamber configured to house a substrate having a first lower electrode layer and a second lower electrode layer separated from the first lower electrode layer, wherein the first lower electrode layer and the second lower electrode layer comprise a first conductive material;   a shadow mask over the substrate, wherein the shadow mask comprises a first opening over the first lower electrode layer and a second opening over the second electrode layer;   a source unit configured to deposit one or more semiconductor materials through the first opening to form a first PN junction structure on the first lower electrode layer and through the second opening to form a second PN junction structure on the second lower electrode layer; and   a transport mechanism configured to produce a first translation between the shadow mask and the substrate, wherein the source unit is configured to deposit a second conductive material through the first opening and the second opening to form a first upper electrode layer on the first PN junction structure and partially on the second lower electrode layer, and to form a second upper electrode layer on the second PN junction structure.   
     
     
         2 . The apparatus of  claim 1 , wherein the source unit is further configured to deposit the first conductive material through the first opening and the second opening to form the first lower electrode layer and the second lower electrode layer separated from the first lower electrode layer. 
     
     
         3 . The apparatus of  claim 2 , wherein the transport mechanism configured to produce a second translation between the shadow mask and the substrate parallel to an upper surface of the substrate before the one or more semiconductor materials are deposited, wherein the first translation and the second translation are substantially along a same direction. 
     
     
         4 . The apparatus of  claim 1 , wherein the first translation is substantially parallel to an upper surface of the substrate. 
     
     
         5 . The apparatus of  claim 1 , wherein each of the first PN junction structure and the second PN junction structure is partially on the substrate. 
     
     
         6 . The apparatus of  claim 1 , wherein the first lower electrode layer, the first PN junction structure, and the first upper electrode layer form a first photovoltaic cell, wherein the second lower electrode layer, the second PN junction structure, and the second upper electrode layer form a second photovoltaic cell that is serially connected to the first photovoltaic cell. 
     
     
         7 . The apparatus of  claim 1 , wherein the source unit is configured to produce material deposition using physical vapor deposition (PVD) or chemical vapor deposition (CVD). 
     
     
         8 . The apparatus of  claim 1 , wherein the shadow mask comprises:
 a frame comprising two opposing arms; and   a crossbar mounted across the two opposing arms, wherein the frame and the crossbar define the first opening and the second opening.   
     
     
         9 . The apparatus of  claim 8 , wherein the crossbar comprises a mounting member configured to be mounted to one of the two opposing arms and a spring configured to pull the mounting member against the one of the two opposing arms to securely mount the crossbar across the two opposing arms. 
     
     
         10 . The apparatus of  claim 8 , wherein the crossbar has a width in a range of about 0.02 millimeter and about 2 millimeters. 
     
     
         11 . The apparatus of  claim 8 , wherein the crossbar comprises Inconel, stainless steel, Kovar, Invar, steel, Titanium, Mo, or W. 
     
     
         12 . The apparatus of  claim 8 , wherein the frame comprises Stainless steel, steel, aluminum, titanium, Kovar, or Invar. 
     
     
         13 . The apparatus of  claim 1 , wherein the shadow mask is positioned at a distance smaller than about 2 millimeters from the substrate. 
     
     
         14 . The apparatus of  claim 1 , further comprising a heating element configured to heat the substrate when the one or more semiconductor materials are deposited on the substrate. 
     
     
         15 . A method for fabricating photovoltaic-cell modules, comprising:
 positioning a shadow mask over a substrate, wherein the substrate comprises a first lower electrode layer and a second lower electrode layer separated from the first lower electrode layer, wherein the first lower electrode layer and the second lower electrode layer comprise a first conductive material, wherein the shadow mask comprises a first opening over the first lower electrode layer and a second opening over the second electrode layer;   depositing one or more semiconductor materials, by a source unit, through the first opening to form a first PN junction structure on the first lower electrode layer and through the second opening to form a second PN junction structure on the second lower electrode layer;   producing, by a translation mechanism, a first translation between the shadow mask and the substrate; and   depositing a second conductive material through the first opening and the second opening to form a first upper electrode layer on the first PN junction structure and partially on the second lower electrode layer, and to form a second upper electrode layer on the second PN junction structure.   
     
     
         16 . The method of  claim 15 , further comprising:
 after the step of positioning the shadow mask over a substrate, depositing the first conductive material through the first opening and the second opening to form the first lower electrode layer and the second lower electrode layer separated from the first lower electrode layer.   
     
     
         17 . The method of  claim 16 , further comprising: after the step of depositing the first conductive material, producing a second translation, by a translation mechanism, between the shadow mask and the substrate parallel to an upper surface of the substrate, wherein the first translation and the second translation are substantially along a same direction. 
     
     
         18 . The method of  claim 15 , wherein the first translation is substantially parallel to an upper surface of the substrate. 
     
     
         19 . The method of  claim 15 , wherein each of the first PN junction structure and the second PN junction structure is partially on the substrate. 
     
     
         20 . The method of  claim 15 , wherein the first lower electrode layer, the first PN junction structure, and the first upper electrode layer form a first photovoltaic cell, wherein the second lower electrode layer, the second PN junction structure, and the second upper electrode layer form a second photovoltaic cell that is serially connected to the first photovoltaic cell. 
     
     
         21 . The method of  claim 15 , wherein the steps of depositing a first conductive material, depositing one or more semiconductor materials, and depositing a second conductive material comprises depositing the first conductive material, the one or more semiconductor materials, or the second conductive material using physical vapor deposition (PVD) or chemical vapor deposition (CVD). 
     
     
         22 . The method of  claim 21 , further comprising heating the substrate before or during the step of depositing the one or more semiconductor materials.