Deposition methods for high quality reflectance coatings

Abstract

Low-emissivity coatings that are highly reflective to infrared-radiation. The coating includes three infrared-reflection film regions, which may each include silver.

What is claimed is: 
     
         1 . A method for depositing film onto a glass sheet, the method comprising:
 a) providing a coater having an extended series of sputtering chambers and a path of substrate travel extending through the sputtering chambers, the coater including downward coating equipment mounted above the path of substrate travel, the extended series of sputtering chambers including at least 60 sputtering chambers, at least some of the sputtering chambers being adapted for downward sputtering and including upper sputtering targets mounted above the path of substrate travel;   b) conveying the glass sheet along the path of substrate travel in a generally horizontal orientation wherein a top major surface of the glass sheet is oriented upwardly and a bottom major surface of the glass sheet is oriented downwardly; and   c) operating the downward coating equipment to deposit upon the top major surface of the glass sheet a coating including a sequence of at least seven film regions comprising, moving outwardly from the top major surface of the glass sheet, a first transparent dielectric film region, a first infrared-reflective film region comprising silver, a second transparent dielectric film region, a second infrared-reflective film region comprising silver, a third transparent dielectric film region, a third infrared-reflective film region comprising silver, and a fourth transparent dielectric film region;   the method comprising depositing said at least seven film regions in a single pass of the glass sheet through the coater, and wherein during this single pass the glass sheet is conveyed at a conveyance rate of 300 inches per minute or faster.   
     
     
         2 . The method of  claim 1  wherein the first, second, and third infrared-reflective film regions comprising silver are each deposited at a thickness of between about 50 angstroms and about 300 angstroms. 
     
     
         3 . The method of  claim 1  wherein each of the first, second, and third transparent dielectric film regions comprises an oxide layer in contact with one of the infrared-reflective film regions comprising silver, and each such oxide layer comprises zinc tin oxide having a metal-only ratio of tin weight divided by total zinc plus tin weight of greater than 0 but less than 0.3. 
     
     
         4 . The method of  claim 1  wherein said operating the downward coating equipment includes simultaneously sputtering silver in at least three of the sputtering chambers adapted for downward sputtering. 
     
     
         5 . The method of  claim 1  wherein said conveyance rate is maintained substantially constant throughout an entirety of said single pass of the glass sheet through the coater. 
     
     
         6 . The method of  claim 1  wherein the coater's extended series of sputtering chambers includes at least 39 downward sputtering chambers each including at least one of the upper sputtering targets. 
     
     
         7 . The method of  claim 1  wherein the glass sheet has a major dimension of at least 2 meters, and the method comprises entirely coating both the top and bottom major surfaces of the glass sheet in said single pass of the glass sheet through the coater. 
     
     
         8 . The method of  claim 1  wherein said single pass of the glass sheet through the coater is continuous in that the glass sheet is not interrupted by removing the glass sheet from the coater during said single pass. 
     
     
         9 . The method of  claim 1  wherein said coating including the sequence of at least seven film regions comprises a plurality of nitride films.