Hollow cathode sputtering apparatus and related method

Abstract

The present invention provides an improved hollow cathode method for sputter coating a substrate. The method of the invention comprises providing a channel for gas to flow through, the channel defined by a channel defining surface wherein one or more portions of the channel-defining surface include at least one target material. Gas is flowed through the channel wherein at least a portion of the gas is a non-laminarly flowing gas. While the gas is flowing through the channel a plasma is generated causing target material to be sputtered off the channel-defining surface to form a gaseous mixture containing target atoms that is transported to the substrate. In an important application of the present invention, a method for forming oxide films and in particular zinc oxide films is provided.

1 . A method for sputter coating a substrate in a sputter coating reactor, the method comprising: 
 a) providing a channel for gas to flow through, the channel defined by a channel defining surface wherein one or more portions of the channel-defining surface include at least one target material;    b) flowing gas through the channel wherein at least a portion of the gas is a non-laminarly flowing gas; and    c) generating a plasma, wherein the target material is sputtered off the channel-defining surface to form a gaseous mixture containing target atoms that is transported to the substrate.    
     
     
         2 . The method of  claim 1  wherein the non-laminarly flowing gas is formed by turbulence.  
     
     
         3 . The method of  claim 1  wherein the non-laminarly flowing gas is formed by flowing a first portion of gas in a first direction and a second portion of gas in a second direction wherein the first direction and the second direction are substantially non-parallel.  
     
     
         4 . The method of  claim 1  wherein the non-laminarly flowing gas is formed by flowing the gas through at least two orifices such that at least two gas streams emerging from the at least two orifices are flowing in substantially non-parallel directions.  
     
     
         5 . The method of  claim 1  wherein the non-laminarly flowing gas is formed flowing the gas through a series of orifices such that adjacent orifices direct the gas in non-parallel directions.  
     
     
         6 . The method of  claim 1  wherein the non-laminarly flowing gas is formed by turbulence with a Reynolds number greater than 2000.  
     
     
         7 . The method of  claim 1  wherein the channel-defining surface is part of a cathode.  
     
     
         8 . The method of  claim 1  wherein the channel has a rectangular cross section.  
     
     
         9 . The method of  claim 1  wherein the target material is in electrical contact with a DC potential, a DC potential with a superimposed AC potential, or a pulsed DC potential.  
     
     
         10 . The method of  claim 1  wherein the target material is in electrical contact with a pulsed DC power source that is an asymmetric bipolar pulsed DC power supply.  
     
     
         11 . The method of  claim 1  wherein the at least one target material comprises a metal or metal alloy.  
     
     
         12 . The method of  claim 1  wherein the at least one target material comprises a component selected from the group consisting of zinc, copper, aluminum, silicon, tin, indium, magnesium, titanium, chromium, molybdenum, nickel, yttrium, zirconium, niobium, cadmium, and mixtures thereof.  
     
     
         13 . The method of  claim 1  wherein the at least one target material includes a first target material and a second target material, the first target material being opposite the second and wherein the first target material and the second target material are the same or different.  
     
     
         14 . The method of  claim 13  wherein the first target material and the second target material comprise a metal or a metal alloy.  
     
     
         15 . The method of  claim 13  wherein the first target material and the second target material independently include a component selected from the group consisting of zinc, copper, aluminum, silicon, tin, indium, magnesium, titanium, chromium, molybdenum, nickel, yttrium, zirconium, niobium, cadmium, and mixtures thereof.  
     
     
         16 . The method of  claim 13  wherein the at least one target material includes a third target material and a fourth target material, the third target material being opposite the fourth target material and wherein the first target material, the second target material, the third target material, and the fourth target material are the same or different.  
     
     
         17 . The method of  claim 13  wherein the at least one target material includes a first electrically insulating block and a second electrically insulating block, the first insulating block being opposite the second insulating.  
     
     
         18 . The method of  claim 13  further comprising introducing a reactive gas into the sputter coating reactor.  
     
     
         19 . The method of  claim 18  wherein the reactive gas is introduced at a position located outside of the channel from which the gaseous mixture emerges.  
     
     
         20 . The method of  claim 18  wherein the reactive gas contains an atom selected from the group consisting of oxygen, nitrogen, selenium, sulfur, iodine, hydrogen, carbon, boron, and phosphorus.