Apparatus and method for wet cleaning or etching a flat substrate

Abstract

An apparatus for wet cleaning or etching of flat substrates comprising a tank with an inlet opening and outlet opening for said substrates. Said tank contains a cleaning liquid and is installed in a gaseous environment. At least one of the openings is a slice in a sidewall of the tank and is present below the liquid-surface. In the tank there may be a portion above the liquid filled with a gas with a pressure being lower than the pressure within said environment. The method comprises the step of transferring a substrate through the cleaning or etching liquid at a level underneath the surface of said liquid making use of said apparatus.

What is claimed is:  
     
         1 . An apparatus for wet cleaning or etching a flat substrate, comprising: 
 a tank containing at least one cleaning or etching liquid and being installed in an environment, said environment consisting essentially of a gas or of a mixture of gases;    an opening in said tank, said opening being below the liquid surface; and    means to prevent said liquid from flowing through said opening out of said tank into said environment.    
     
     
         2 . The apparatus of  claim 1 , wherein said means are realized by the dimensions of said opening, said opening being narrow such that the liquid is prevented from flowing through it due to a surface tension between the liquid and at least one surface of said tank adjacent to said opening.  
     
     
         3 . The apparatus of  claim 1 , wherein said means are realized by the dimensions of said opening, said opening being narrow such that the liquid is prevented from flowing through it due to a capillary effect provided by said liquid.  
     
     
         4 . The apparatus of  claim 1 , wherein said means are realized by the dimensions of said opening, said opening being narrow such that the liquid is prevented from flowing through it due to a capillary effect provided by said liquid and a surface tension between the liquid and at least one surface of said tank adjacent to said opening.  
     
     
         5 . The apparatus of  claim 4 , wherein said opening is marginally larger than the thickness of said substrate.  
     
     
         6 . The apparatus of  claim 4 , wherein said opening is marginally larger than the thickness of said substrate and is configured as an elongated passage, the length of said passage.  
     
     
         7 . The apparatus of  claim 4 , wherein said opening is marginally larger than the thickness of said substrate and said opening is a passage which converges towards said environment.  
     
     
         8 . The apparatus of  claim 1 , wherein said means comprises a room adjacent to said tank, said room having an opening for said substrates and said room being filled with a gas or gas mixture with a pressure being higher than the pressure within said environment.  
     
     
         9 . The apparatus of  claim 1 , wherein said means comprises a second portion in the tank, said second portion being above said liquid and being filled with a gas or a gas mixture with a pressure being lower than the pressure within said environment.  
     
     
         10 . The apparatus of  claim 9 , wherein said means comprises a pump connected with said second portion in the tank for sucking the gas, thereby reducing the gas-pressure in said second portion and subsequently reducing the liquid-pressure near said opening.  
     
     
         11 . The apparatus of  claim 1 , wherein said means comprises partitions inside the tank to increase a capillary force, thereby reducing a liquid-pressure near said opening.  
     
     
         12 . The apparatus of  claim 1 , wherein said liquid is a dilute chemical.  
     
     
         13 . The apparatus of  claim 1 , wherein said means comprises means outside the tank for directing a gas flow towards said opening.  
     
     
         14 . The apparatus of  claim 13 , wherein said gas flow comprises N 2  as a constituent of the gas flow mixture.  
     
     
         15 . The apparatus of  claim 13 , wherein said gas flow comprises a vapor which does not condensing on said substrate at said opening, said vapor being chosen from a group of substances which are miscible with said liquid and which will form with said liquid a mixture having a surface tension lower than that of said liquid alone.  
     
     
         16 . The apparatus of  claim 15 , wherein the vapor comprises IPA.  
     
     
         17 . The apparatus of  claim 1 , comprising an inlet opening and an outlet opening, said inlet opening being in a first sidewall of said tank and said outlet opening being in a second sidewall of said tank, said substrate being passed essentially horizontally through said apparatus.  
     
     
         18 . The apparatus of  claim 1 , comprising an inlet opening and an outlet opening, said inlet opening being in a bottom wall of said tank and said outlet opening being in a top wall of said tank, said substrate being passed essentially vertically through said apparatus.  
     
     
         19 . The apparatus of  claim 1 , wherein said flat substrate is a semiconductor wafer and said environment is a clean room.  
     
     
         20 . The apparatus of  claim 1 , wherein said apparatus is adjacent to a process chamber being part of the manufacturing line of said substrate, said substrate being passed from within said apparatus into said process chamber.  
     
     
         21 . A method of wet cleaning or etching a flat substrate in a tank filled with at least one cleaning or etching liquid, said method comprising the steps of: 
 loading from within a gaseous environment said substrate through an inlet opening in said tank, said inlet opening being at a level underneath the surface of said liquid; and    unloading said substrate out of the tank into said gaseous environment while preventing said liquid from flowing out of said tank.    
     
     
         22 . The method of  claim 21 , wherein a gas is present above the liquid in the tank, said gas being sucked out of the tank to reduce the pressure inside the tank.  
     
     
         23 . The method of  claim 21 , wherein a gas flow is directed towards said opening from outside the tank, and wherein said gas flow dries the substrate and prevents the liquid from flowing out of the tank.  
     
     
         24 . A method of wet cleaning or etching a flat substrate comprising the step of transferring said substrate through a tank filled with a liquid, said substrate being introduced into said tank through an inlet opening and taken out of said tank through an outlet opening underneath the liquid-surface, wherein said substrate is introduced into the tank from a gaseous environment and transferred at a uniform speed through said liquid, thereby exposing each part of said substrate to said liquid for essentially the same time period.  
     
     
         25 . An apparatus for wet cleaning or etching a flat substrate, comprising: 
 a tank containing at least one cleaning or etching liquid and being installed in an environment, said environment consisting essentially of a gas or of a mixture of gases;    an opening in said tank, said opening being below the liquid surface and configured to prevent said liquid from flowing through said opening out of said tank into said environment.