System and method for controlling deposition thickness by synchronously varying a sputtering rate of a target with respect to an angular position of a rotating substrate

Abstract

A system and method for controlling a circumferential deposition thickness distribution on a substrate includes a motor that rotates the substrate and a positioning sensor that senses an angular position of the substrate. At least one deposition thickness sensor senses the deposition thickness of the substrate at multiple positions on a circumference of a circle centered about an axis of rotation of the substrate. At least one controller drives a vapor source used to emit material for a deposition on a substrate. The at least one controller is coupled to the positioning sensor and the deposition thickness sensor. The controller synchronously varies an emission rate of material from the vapor source with respect to the angular position of the substrate to control the circumferential deposition thickness distribution.

What is claimed is:  
     
         1 . A system for controlling a circumferential deposition thickness distribution on a substrate comprising: 
 (a) a motor that rotates the substrate;    (b) a positioning sensor that senses an angular position of the substrate;    (c) at least one deposition thickness sensor that senses the deposition thickness of the substrate at multiple positions on a circumference of a circle centered about an axis of rotation of the substrate;    (d) a target power supply that drives a target used to sputter material on the substrate;    (e) a process controller coupled to the positioning sensor, the deposition thickness sensor, and the target power supply; and    (f) wherein the process controller synchronously varies a sputtering rate of the target with respect to the angular position of the substrate to control the circumferential deposition thickness distribution.    
     
     
         2 . The system of  claim 1 , wherein the sensor is an optical sensor.  
     
     
         3 . The system of  claim 1 , wherein the deposition thickness is determined by the process controller in response to an output of the deposition thickness sensor and a target bias signal that is proportional to the sputtering rate.  
     
     
         4 . The system of  claim 1 , wherein the process controller varies the sputtering rate by varying a target bias signal.  
     
     
         5 . The system of  claim 1 , wherein the process controller modifies a pulse train output by the position sensor to generate the target bias signal which changes a deposition rate on the substrate when a portion of the rotating substrate proximate the target has a deposition thickness that requires modification to match a desired deposition thickness.  
     
     
         6 . The system of  claim 5 , wherein a pulse train output by the position sensor is modified by the process controller to generate the target bias signal by adding or omitting pulses from the target bias signal.  
     
     
         7 . The system of  claim 1 , wherein the process controller varies the sputtering rate by varying a duty cycle of a target bias signal.  
     
     
         8 . The system of  claim 1 , wherein the process controller varies the sputtering rate by varying an amplitude of a target bias signal.  
     
     
         9 . The system of  claim 1 , wherein the process controller varies the sputtering rate by varying a frequency of a target bias signal.  
     
     
         10 . A method for controlling a circumferential deposition thickness distribution on a substrate, the method comprising the steps of: 
 (a) rotating the substrate with a motor;    (b) sensing an angular position of the substrate with a positioning sensor;    (c) sensing the deposition thickness of the substrate at multiple positions on a circumference of a circle centered about an axis of rotation of the substrate with at least one deposition thickness sensor; and    (d) synchronously varying a sputtering rate of a target with respect to the angular position of the substrate, in response to outputs of the positioning sensor and the deposition thickness sensor, to control the circumferential deposition thickness distribution on the substrate.    
     
     
         11 . An optical filter comprising: 
 (a) a substrate; and    (b) a material deposited on the substrate using a motor that rotates the substrate, at least one deposition thickness sensor that senses the deposition thickness of the substrate at multiple positions on a circumference of a circle centered about an axis of rotation of the substrate, a target power supply that drives a target used to sputter material on the substrate and a process controller coupled to the positioning sensor, the deposition thickness sensor, the target power supply; and wherein the process controller synchronously varies a sputtering rate of the target with respect to the angular position of the substrate to control a circumferential deposition thickness distribution on the substrate.    
     
     
         12 . A system for controlling a circumferential deposition thickness distribution on a substrate comprising: 
 (a) a motor that rotates the substrate;    (b) a positioning sensor that senses an angular position of the substrate;    (c) at least one deposition thickness sensor that senses the deposition thickness of the substrate at multiple positions on a circumference of a circle centered about an axis of rotation of the substrate;    (d) at least one controller that drives a vapor source used to emit material for deposition on the substrate, said at least source controller being coupled to the positioning sensor and the deposition thickness sensor; and    (e) wherein the controller synchronously varies an emission rate of material from the vapor source with respect to the angular position of the substrate to control the circumferential deposition thickness distribution.    
     
     
         13 . The system of  claim 12 , wherein the at least one controller comprises a vapor source controller that drives the vapor source, and a process controller coupled to the vapor source controller, the positioning sensor and the deposition thickness sensor, wherein the process controller synchronously varies the emission rate of material from the vapor source with respect to the angular position of the substrate to control the circumferential deposition thickness distribution.  
     
     
         14 . A method for controlling a circumferential deposition thickness distribution on a substrate comprising: 
 (a) rotating a substrate with a motor;    (b) sensing an angular position of the substrate with a positioning sensor;    (c) sensing the deposition thickness of the substrate at multiple positions on a circumference of a circle centered about an axis of rotation of the substrate with at least one deposition thickness sensor; and    (d) synchronously varying an emission rate of material from the vapor source with respect to the angular position of the substrate, in response to outputs of the positioning sensor and the deposition thickness sensor, to control the circumferential deposition thickness distribution.    
     
     
         15 . An optical filter comprising: 
 (a) a substrate; and    (b) a material deposited on the substrate using a motor that rotates the substrate, a positioning sensor that senses an angular position of the substrate, at least one deposition thickness sensor that senses the deposition thickness of the substrate at multiple positions on a circumference of a circle centered about an axis of rotation of the substrate, at least one controller that drives a vapor source used to emit material for deposition on the substrate, said at least one controller coupled to the positioning sensor and the deposition thickness sensor; and wherein the at least one controller synchronously varies an emission rate of material from the vapor source with respect to the angular position of the substrate to control a circumferential deposition thickness distribution on the substrate.