Plasma Spraying and Recrystallization of Thick Film Layer

Abstract

A linear process tool comprising at least two deposition modules each comprising one or more plasma spray guns operable to move in a direction approximately orthogonal to the direction of a substrate carrier is configured to deposit at least a first and second layer, in direct contact with each other, wherein a first layer is of first composition and the second layer is of second composition different than the first composition.

1 . A linear process tool comprising;
 first and second deposition modules each comprising one or more plasma spray guns operable to move in a direction approximately orthogonal to the direction of motion of a substrate carrier; wherein the first deposition module is configured to deposit a first layer on a substrate on the substrate carrier and the second deposition module is configured to deposit a second layer in direct contact with the first layer on the substrate on the substrate carrier such that the first layer is of first composition and the second layer is of second composition different than the first composition; wherein the plasma spray guns comprise components exposed to the plasma stream comprising at least one constituent of the primary source material in the plasma stream; wherein the primary source of materials for the plasma spray guns for the deposited layers is a first and second powder of first and second compositions produced by jet mills wherein the substrate carrier conveys the substrate from an entrance of the linear process tool to an exit at a predetermined speed.   
     
     
         2 . The linear process tool of  claim 1  further comprising a zone melt recrystallization module comprising a source of radiation; and
 optical components operable to convert the source of radiation into a linear line of radiation ranging from about 0.5 mm to 3 mm wide extending across the width of the substrate placed on the substrate carrier such that a portion of the deposited material layer on the substrate is irradiated in the linear line of radiation and heated at least to the melting point of the deposited material for a predetermined time; such that as the portion of the substrate with a deposited material layer passes out from underneath the linear line of radiation the deposited material layer portion now outside the radiated zone cools below its melting point and recrystallizes into a preferred orientation based on its composition.   
     
     
         3 . The linear process tool of  claim 1  wherein the recrystallized deposited material layer exhibits a minority carrier diffusion length greater than 40 microns and a grain size larger than the deposited material layer thickness. 
     
     
         4 . The linear process tool of  claim 1  further comprising means for ultrasonic vibration applied to the portion of the deposited material layer on the substrate being irradiated in the linear line of radiation and heated at least to the melting point. 
     
     
         5 . The linear process tool of  claim 1  wherein the substrate is flexible. 
     
     
         6 . The linear process tool of  claim 5  wherein the flexible substrate is configured such that it enters the linear process tool from a roll and exits the linear process tool on to a roll. 
     
     
         7 . The linear process tool of  claim 1  wherein the first and second compositions are chosen substantially from a group consisting of silicon, silicon-germanium alloys, Group IV elements and/or alloys, Group IV oxides, nitrides, carbides and mixtures thereof, metal oxides, nitrides, carbides and mixtures thereof. 
     
     
         8 . A method for making a structure comprising first layer of first composition and second layer of second composition in contact wherein the first composition is different from the second composition comprising the steps:
 depositing the first layer on a transported substrate with a first plasma spray gun operable to move in a direction approximately orthogonal to the transported direction; and   depositing the second layer on the transported substrate with a second plasma spray gun operable to move in a direction approximately orthogonal to the transported direction; wherein the first plasma spray gun comprises components exposed to the plasma stream comprising at least one constituent of a first primary source material in the plasma stream; wherein the first primary source material for the first plasma spray gun for the first layer is a first powder of the first composition produced by jet mills; wherein the second plasma spray gun comprises components exposed to the plasma stream comprising at least one constituent of a second primary source material in the plasma stream; wherein the second primary source material for the second plasma spray gun for the second layer is a second powder of the second composition produced by jet mills.   
     
     
         9 . The method for making a structure of  claim 8  further comprising the step of:
 heating a portion of the transported substrate to initiate zone melt recrystallization in a linear line ranging from about 0.5 mm to 3 mm wide extending across the width of the transported substrate to the melting point of the deposited material for a predetermined time; and cooling and recrystallizing the previously heated portion of the transported substrate into a preferred orientation based on its composition.   
     
     
         10 . The method for making a structure of  claim 9  wherein the recrystallized portion of the transported substrate exhibits a minority carrier diffusion length greater than 40 microns and a grain size larger than the deposited material layer thickness. 
     
     
         11 . The method for making a structure of  claim 9  further comprising the step:
 applying ultrasonic vibration to the portion of the transported substrate being heated to initiate zone melt recrystallization.   
     
     
         12 . The method for making a structure of  claim 9  wherein the transported substrate is flexible. 
     
     
         13 . The method for making a structure of  claim 8  wherein the first and second compositions are chosen substantially from a group consisting of silicon, silicon-germanium alloys, Group IV elements and/or alloys, Group IV oxides, nitrides, carbides and mixtures thereof, metal oxides, nitrides, carbides and mixtures thereof.