Roll-to-roll evaporation system and method to manufacture group ibiiiavia photovoltaics

Abstract

The present inventions provide method and apparatus that employ constituents vaporized from one or more constituent supply source or sources to form one or more films of a precursor layer formed on a surface of a continuous flexible workpiece. Of particular significance is the implementation of vapor deposition systems that operate upon a horizontally disposed portion of a continuous flexible workpiece and a vertically disposed portion of a continuous flexible workpiece, preferably in conjunction with a short free-span zone of the portion of a continuous flexible workpiece.

1 . A roll-to-roll system for depositing a plurality of films of Group IA and Group VIA materials on a front surface of a continuous sheet shaped workpiece that is advanced in a process direction, comprising:
 a process housing through which the continuous sheet shaped workpiece is advanced between an entrance opening and an exit opening of the process housing, the process housing including a first process section located by a horizontal peripheral wall of the process housing and a second process section located by a vertical peripheral wall of the process housing, wherein the first process section is associated with a horizontally disposed portion of the continuous sheet shaped workpiece and the second process section is associated with a vertically disposed portion of the continuous sheet shaped workpiece;   a workpiece tensioning and drive assembly for advancing the continuous sheet shaped workpiece in the process direction between the entrance opening and the exit opening of the process housing;   a first deposition station including at least a first deposition unit disposed at the first process section to continuously deposit a first film onto the horizontally disposed portion of the continuous sheet shaped workpiece as the continuous sheet shaped workpiece is advanced through the at least first deposition unit; and   a second deposition station including at least a second deposition unit disposed at the second process section to continuously deposit a second film onto the vertically disposed portion of the continuous sheet shaped workpiece as the continuous sheet shaped workpiece is advanced through the at least second deposition unit;   wherein one of the first and second deposition stations deposits directly onto a front surface portion of the continuous sheet shaped workpiece to obtain a new front surface portion and the other of the first and second deposition stations deposits onto the new front surface portion.   
     
     
         2 . The system of  claim 1  wherein the first deposition station deposits directly onto the front surface portion of the continuous sheet shaped workpiece to obtain the new front surface portion and the second deposition station deposition stations deposits onto the new front surface portion. 
     
     
         3 . The system of  claim 2  wherein the depositing of the second film occurs while no physical contact exists with a corresponding back surface of the vertically disposed portion of the continuous sheet shaped workpiece disposed within the second deposition unit as the second film is deposited 
     
     
         4 . The system of  claim 2  further comprising a loading chamber and an unloading chamber sealably connected to the entrance opening and the exist opening of the process housing respectively. 
     
     
         5 . The system of  claim 2 , wherein the loading chamber includes a supply roll from which the continuous sheet shaped workpiece is advanced using the workpiece tensioning and drive assembly into the process housing through the entrance opening, and wherein the unloading chamber includes a receiving roll that the continuous sheet shaped workpiece received from the process housing through the exit opening wraps around. 
     
     
         6 . The system of  claim 5 , wherein the unloading station includes a metrology tool to measure thicknesses of the first and second films and provides feed back of the measured thicknesses of the first and second films to a deposition control system. 
     
     
         7 . The system of  claim 5 , wherein the horizontally disposed portion of the continuous sheet shaped workpiece is disposed within the first process section in a horizontal free-span zone in which the horizontally disposed portion of the continuous sheet shaped workpiece is unsupported, the horizontal free span zone being established between a first roller and a second roller by tensioning the horizontally disposed portion of the continuous sheet shaped workpiece between the first roller and a second roller on which the back surface of the horizontally disposed portion of the continuous sheet shaped workpiece rests using the workpiece tensioning and drive assembly as the continuous sheet shaped workpiece is advanced within the first process section, wherein the horizontally disposed portion of the continuous sheet shaped workpiece is substantially flat in the horizontal free-span zone. 
     
     
         8 . The system of  claim 7 , wherein a first sealable opening is placed between the first roller and the first process section, and a second sealable opening is placed between the first process section and the second roller to seal the first process section, and wherein the continuous sheet shaped workpiece passes through the first and the second sealable openings. 
     
     
         9 . The system of  claim 8 , wherein the vertically disposed portion of the continuous sheet shaped workpiece is disposed within the second process section in a vertical free-span zone in which the vertically disposed portion of the continuous sheet shaped workpiece is unsupported, the vertical free span zone being established by tensioning the vertically disposed portion of the continuous sheet shaped workpiece between the second roller and a third roller on which the back surface of the vertically disposed portion of the continuous sheet shaped workpiece rests using the workpiece tensioning and drive assembly as the continuous sheet shaped workpiece is advanced within the second process section, wherein the vertically disposed portion of the continuous sheet shaped workpiece is substantially flat in the vertical free-span zone. 
     
     
         10 . The system of  claim 9 , wherein a third sealable opening is placed between the second roller and the second process section, and a fourth sealable opening is placed between the second process section and the third roller to seal the second process section, and wherein the continuous sheet shaped workpiece passes through the third and the fourth sealable openings. 
     
     
         11 . The system of  claim 2 , wherein the at least first deposition unit includes a first evaporation apparatus to vapor deposit the first film, and the at least second deposition unit includes a second evaporation apparatus to vapor deposit the second film. 
     
     
         12 . The system of  claim 11 , wherein inner surfaces of the first and second peripheral walls are each shielded with a protective shield to collect excess vapor from the first and second evaporation apparatus. 
     
     
         13 . The system of  claim 11 , wherein the first evaporation apparatus deposits a Group IA material and the second evaporation apparatus deposits a Group VIA material. 
     
     
         14 . The system of  claim 13 , wherein the Group VIA material is Se, and wherein the Group IA material is one of Na, K and Li. 
     
     
         15 . The system of  claim 11 , wherein the unloading station includes a metrology tool to measure thicknesses of the first and second films and provides feed back of the measured thicknesses of the first and second films to a deposition control system. 
     
     
         16 . The system of  claim 15 , wherein the deposition control system controls the first evaporation apparatus, the second evaporation apparatus and the workpiece tensioning and drive assembly. 
     
     
         17 . The system of  claim 2 , wherein the deposition of the first film occurs while no physical contact exists with a corresponding back surface of the horizontally disposed portion of the continuous sheet shaped workpiece disposed within the at least first deposition unit as the first film is deposited. 
     
     
         18 . The system of  claim 1 , wherein the at least second deposition unit includes an evaporation apparatus to vapor deposit the second film. 
     
     
         19 . The system of  claim 16  wherein the evaporation apparatus is a Se evaporation apparatus that vapor deposits a Se film as the second film. 
     
     
         20 . The system of  claim 1  further comprising a sealable gate separating the first process section from the second process section thereby preventing cross contamination therebetween. 
     
     
         21 . The system of  claim 1  further comprising a cooling system disposed after the at least second deposition unit in the process direction to cool that portion of the continuous sheet shaped workpiece that passes therethrough. 
     
     
         22 . A method of vapor depositing a plurality of films of Group IA and Group VIA materials on a front surface of a continuous workpiece that is advanced in a process direction in a roll-to-roll deposition system, comprising:
 advancing the continuous workpiece in a process direction between an entrance opening and an exit opening of a process housing, the process housing including a first process section and a second process section, wherein the first process section is associated with a horizontally disposed portion of the continuous workpiece and the second process section is associated with a vertically disposed portion of the continuous workpiece;   depositing a first film over a front surface portion of the front surface of the horizontally disposed portion of the continuous workpiece, wherein the deposition of the first film uses at least one first evaporation deposition apparatus disposed at the first process section to continuously deposit the first film on a portion of the front surface of the continuous workpiece as the continuous workpiece is advanced through the at least one first evaporation deposition apparatus; and   depositing a second film over a surface portion of the first film of the front surface of the vertically disposed portion of the continuous workpiece, wherein the deposition of the second film uses at least one second evaporation deposition apparatus disposed at the second process section to continuously deposit the second film on a portion of the front surface of the first film of the continuous workpiece as the continuous workpiece is advanced through the at least one second evaporation deposition apparatus.   
     
     
         23 . The method of  claim 22  wherein the first film comprises a Group IA material and the second film comprises a Group VIA material. 
     
     
         24 . The method of  claim 23  wherein the Group VIA material is Se, and wherein the Group IA material is one of Na, K and Li. 
     
     
         25 . The method of  claim 22 , wherein the step of deposition the first film includes depositing the first film over a precursor film formed on the front surface of the continuous workpiece, the precursor film including at least one Group IB material and at least one Group IIIA material. 
     
     
         26 . The method of  claim 25 , wherein the precursor film is formed over a base of the continuous workpiece, wherein the base including a substrate and a contact layer formed on the substrate. 
     
     
         27 . The method of  claim 26 , wherein the substrate including one of stainless steel foil and aluminum foil, and the contact layer comprising at least one of Mo, Ru and Os. 
     
     
         28 . The method of  claim 22 , and wherein the deposition of the second film occurs while no physical contact is established with a corresponding back surface portion of the vertically disposed portion of the continuous workpiece to support the back surface thereof as the second film is deposited and as the continuous workpiece is advanced through the at least one second evaporation deposition apparatus. 
     
     
         29 . The method of  claim 22 , wherein the deposition of the first film occurs while no physical contact is established with a corresponding back surface portion of the horizontally disposed portion of the continuous workpiece to support the back surface thereof as the first film is deposited and as the continuous workpiece is advanced through the at least one first evaporation deposition apparatus. 
     
     
         30 . The method of  claim 22  further comprising the step of tensioning the continuous workpiece while advancing the continuous workpiece in a process direction. 
     
     
         31 . The method of  claim 22 , wherein the horizontally disposed portion of the continuous workpiece is disposed within the first process section in a horizontal free-span zone in which the horizontally disposed portion of the continuous workpiece is unsupported, the horizontal free span zone being established between a first roller and a second roller by tensioning the horizontally disposed portion of the continuous workpiece between the first roller and a second roller on which the back surface of the horizontally disposed portion of the continuous workpiece rests as the continuous workpiece is advanced within the first process section, wherein the horizontally disposed portion of the continuous workpiece is substantially flat in the horizontal free-span zone. 
     
     
         32 . The method of  claim 31 , wherein a first sealable opening is placed between the first roller and the first process section, and a second sealable opening is placed between the first process section and the second roller to seal the first process section, and wherein the continuous workpiece passes through the first and the second sealable openings. 
     
     
         33 . The method of  claim 22 , wherein the vertically disposed portion of the continuous workpiece is disposed within the second process section in a vertical free-span zone in which the vertically disposed portion of the continuous workpiece is unsupported, the vertical free span zone being established by tensioning the vertically disposed portion of the continuous workpiece between the second roller and a third roller on which the back surface of the vertically disposed portion of the continuous workpiece rests as the continuous workpiece is advanced within the second process section, wherein the vertically disposed portion of the continuous workpiece is substantially flat in the vertical free-span zone. 
     
     
         34 . The method of  claim 33 , wherein a third sealable opening is placed between the second roller and the second process section, and a fourth sealable opening is placed between the second process section and the third roller to seal the second process section, and wherein the continuous workpiece passes through the third and the fourth sealable openings.