System for regulating the applied blade-to-boule force during the slicing of wafers
First Claim
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1. In a wafer saw for slicing thin wafers from a boule of source material in which said saw has a saw blade which revolves at high speed for slicing wafers from said boule;
- said saw holds said boule stationary during the slicing of each wafer;
said saw translates said revolving saw blade to cause the cutting surface of said blade to penetrate said stationary boule to slice a wafer from said boule by removing boule material which attaches said wafer to the remainder of said boule and said boule and said saw has a control system for controlling the rate of translation of said blade, the improvement comprising;
means for regulating the blade-to-boule force urging said blade of said saw into said boule during the slicing of wafers to improve the as-sawn quality of the wafers, said means for regulating comprising;
force sensing means for sensing the blade-to-boule force urging said blade of said saw into said boule;
said force sensing means comprising a transducer fixed to said stationary boule for sensing said blade-to-boule force;
force reference means for establishing a desired pattern of blade-to-boule force;
force comparator means for determining whether said sensed blade-to-boule force exceeds said desired blade-to-boule force and for determining whether such sensed blade-to-boule force is less than said desired blade-to-boule force by more than a desired force-hysteresis amount;
control means for decreasing the feedrate of said saw blade into said boule when said force comparator means produces an output indicating that said sensed blade-to-boule force is greater than said desired blade-to-boule force and for increasing said feedrate when said comparator means produces an output indicating that said sensed blade-to-boule force is less than said desired blade-to-boule force by an amount which is greater than said desired force hysteresis amount.
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Abstract
A system for controlling the blade-to-boule feedrate of a wafer cutting saw to regulate the blade-to-boule force in accordance with predetermined criteria and for monitoring the cutting efficiency of the blade and determining when the blade needs to be dressed to increase its cutting efficiency. A constant blade-to-boule force is preferred.
34 Citations
16 Claims
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1. In a wafer saw for slicing thin wafers from a boule of source material in which said saw has a saw blade which revolves at high speed for slicing wafers from said boule;
- said saw holds said boule stationary during the slicing of each wafer;
said saw translates said revolving saw blade to cause the cutting surface of said blade to penetrate said stationary boule to slice a wafer from said boule by removing boule material which attaches said wafer to the remainder of said boule and said boule and said saw has a control system for controlling the rate of translation of said blade, the improvement comprising;means for regulating the blade-to-boule force urging said blade of said saw into said boule during the slicing of wafers to improve the as-sawn quality of the wafers, said means for regulating comprising; force sensing means for sensing the blade-to-boule force urging said blade of said saw into said boule; said force sensing means comprising a transducer fixed to said stationary boule for sensing said blade-to-boule force; force reference means for establishing a desired pattern of blade-to-boule force; force comparator means for determining whether said sensed blade-to-boule force exceeds said desired blade-to-boule force and for determining whether such sensed blade-to-boule force is less than said desired blade-to-boule force by more than a desired force-hysteresis amount; control means for decreasing the feedrate of said saw blade into said boule when said force comparator means produces an output indicating that said sensed blade-to-boule force is greater than said desired blade-to-boule force and for increasing said feedrate when said comparator means produces an output indicating that said sensed blade-to-boule force is less than said desired blade-to-boule force by an amount which is greater than said desired force hysteresis amount. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
- said saw holds said boule stationary during the slicing of each wafer;
Specification