Method and apparatus for drying a substrate

Abstract

A method and apparatus for drying a disk-shaped substrate. The substrate is typically a substrate used for the manufacture of magnetic disks, and has a centrally located opening. The substrate is lowered into a liquid bath by a first holder, which also becomes immersed in the bath. The first holder lifts the substrate until the substrate extends partially out of contact with the liquid. A second, dry holder grabs a dry portion of the substrate that extends out of the bath, and continues to lift the substrate out of contact with the liquid. In one embodiment, different portions of the substrate are lifted past the surface of the liquid at different speeds

We claim:  
     
         1 . A method for drying a substrate comprising the acts of: 
 providing a workpiece in a liquid bath, said workpiece being held with a first holder such that said workpiece is immersed in said bath;    raising said workpiece so that a first portion of said workpiece extends out of said bath but a second portion of said workpiece remains in said bath;    causing a second holder to lift said first portion of said workpiece while said second portion is still in said bath, such that the portion of said second holder that lifts said first portion of said workpiece does not come into contact with said liquid during said method; and    raising said workpiece out of contact with said liquid with said second holder after said act of causing.    
     
     
         2 . Method of  claim 1  wherein said providing comprises causing said first holder to lower said workpiece into said liquid, and wherein said first holder is immersed in said liquid after said act of causing said first holder to lower.  
     
     
         3 . Method of  claim 1  wherein said workpiece is a disk-shaped substrate having an opening therein, said act of raising comprising: 
 raising said substrate at a first rate prior to the time the top of said substrate extends out of said liquid;  
 raising said substrate at a second rate lower than said first rate while the top of said substrate breaks the surface of said liquid;  
 raising said substrate at a third rate faster than said second rate after the top of said substrate has broken the surface of said liquid but before the top of said opening breaks the surface of said liquid;  
 raising said substrate at a fourth rate slower than said third rate while the top of said opening breaks the surface of said liquid;  
 raising said substrate at a fifth rate faster than said fourth rate after the top of said opening has broken the surface of said liquid but before the bottom of said opening breaks the surface of said liquid;  
 raising said substrate at a sixth rate slower than said fifth rate while the bottom of said opening breaks the surface of said liquid;  
 raising said substrate at a seventh rate faster than said sixth rate after the bottom of said opening has broken the surface of said liquid but before the bottom of said substrate breaks the surface of said liquid; and  
 raising said substrate at an eighth rate slower than said seventh rate while the bottom of said substrate breaks the surface of said liquid.  
 
     
     
         4 . A method for drying a disk-shaped workpiece, said method comprising the acts of: 
 providing said workpiece in a liquid;    raising said workpiece to remove said workpiece from said liquid, wherein said raising of said workpiece is accomplished at different velocities as said workpiece leaves said liquid.    
     
     
         5 . Method of  claim 4  wherein said workpiece is raised at a first rate while the top of said workpiece is raised past the surface of said liquid, said workpiece is raised at a second rate during a time period after the top of said workpiece is raised past the surface of said liquid, and said workpiece is raised at a third rate while the bottom of said workpiece is raised past the surface of said liquid, said first and third rates being slower than said second rate.  
     
     
         6 . Method of  claim 5  wherein said workpiece has a centrally defined opening, said workpiece being raised at a fourth rate while the top of said centrally defined opening passes the surface of said liquid, said workpiece being raised at a fifth rate during a time period after the top surface of said opening has passed the surface of said liquid but before the bottom of said opening has passed the surface of said liquid, said workpiece being raised at a sixth rate while the bottom of said opening passes the surface of said liquid, said fourth and sixth rates being slower than said fifth rate.  
     
     
         7 . Method of  claim 4  wherein the speed at which said substrate is raised is slower while a slow-drying portion of said substrate is being pushed past the surface of said liquid than while a fast-drying portion of said substrate is being pushed past the surface of said liquid.  
     
     
         8 . Method of  claim 7  wherein the top and bottom of the substrate and the top and bottom of the centrally defined openings comprise slow-drying portions of the substrate, and other portions of the substrate are fast-drying.  
     
     
         9 . Apparatus comprising: 
 a container for containing a liquid bath;    a first holder holding a workpiece in a liquid bath and then raising said workpiece partially out of said liquid bath; and    a second holder which is not immersed in said liquid bath, and which grabs a dry portion of said workpiece after said dry portion of said workpiece extends out of said liquid bath but while a second portion of said workpiece remains within said bath, said second holder raising said workpiece entirely out of said bath.    
     
     
         10 . Apparatus of  claim 9  wherein said first holder moves up at different speeds during the time that said first holder raises said workpiece, and wherein the second holder moves up at different speeds during the time said second holder raises said workpiece.  
     
     
         11 . Apparatus of  claim 9  wherein said first holder is immersed in said liquid at the time said second holder grabs said dry portion.  
     
     
         12 . Apparatus of  claim 9  wherein said second holding structure is never immersed in said liquid.  
     
     
         13 . Apparatus of  claim 9  wherein said first and second holding structures are coupled to motors that raise and lower said first and second holding structures.  
     
     
         14  Apparatus comprising: 
 a container for holding a liquid; and  
 at least a first holder for holding said workpiece while said workpiece is within said liquid, said first holder raising said workpiece out of said liquid at a plurality of different speeds.  
 
     
     
         15  Apparatus of  claim 14  wherein the speed at which said workpiece is raised out of said liquid accommodates different drying rates of different portions of said workpiece.  
     
     
         16  Apparatus of  claim 14  wherein said workpiece is raised at a first rate while the top of said workpiece passes the surface of said liquid, said workpiece being raised at a second rate during a time period after the top of said workpiece passes the surface of said liquid, and said workpiece is raised at a third rate while the bottom of said workpiece passes the surface of said liquid, wherein said second rate is faster than said first and third rates.  
     
     
         17 . Apparatus of  claim 14  wherein said workpiece is a substrate having a central opening therein, said apparatus raising said workpiece at a fourth rate while the top of said central opening passes the surface of said liquid, said workpiece being raised at a fifth rate while the bottom of said opening passes the surface of said liquid, and said workpiece is raised at a sixth rate between the time the top and bottom of said opening passes the surface of said liquid, said sixth rate being greater than said fourth and fifth rates.  
     
     
         18 . Apparatus of  claim 17  comprising a second holder, wherein said first holder raises said workpiece up until a time after the bottom of said opening passes the surface of said liquid, and the second holder raises said workpiece after the bottom of said opening passes the surface of said liquid.  
     
     
         19 . Apparatus of  claim 18  wherein said first holder is moved by a first motor and the second holder is moved by a second motor.