Developing speed should be set by breakpoint.  Developer pH 
     does affect speed, however.  If you are using a batch make-up, 
     your best bet is to check breakpoint frequently, and adjust speed 
     as required.   If you use a feed and bleed replenisher system, pH 
     can be tightly controlled (+\- .4) with ease.  Then, breakpoint 
     will be very stable, as will conveyor speed.  Feed and bleed 
     units are available from a variety of sources, and are fairly 
     inexpensive (10 to 15K).  Charting pH for SPC while using this 
     type of unit will result in great CPK's.  You will also be 
     running a very consistent developing process.  
     
          If you are trying to increase or decrease speed to match 
     other units in an inline DES process, you may have to play with 
     developer concentration.  Check with your resist supplier before 
     making any changes.

     Mark Dowding
     Multek Irvine
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______________________________ Reply Separator _________________________________
Subject: Photoresist developing
Author:  [log in to unmask] at INTERNET_GATEWAY
Date:    7/3/96 3:14 PM


Our process engineer for developing and I have been discussing ways to 
improve that process.  He wants to see if developing solution pH can be 
used to set developer speed.  Is this possible? Anyone else doing this?  
We also are looking for ways to use SPC to improve in this process.  
Anyone want to work with us or discuss this?
     
Lou Hart    Quality Assurance   Compunetics 412-858-6117
     
     
.
     
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