Method and apparatus for substrate temperature control

Abstract

A method and apparatus for gas control is provided. The apparatus may be used for controlling gases delivered to a chamber, controlling the chamber pressure, controlling the delivery of backside gas between a substrate and substrate support and the like. In one embodiment, an apparatus for controlling gas control includes at least a first flow sensor having a control valve, a first pressure sensor and at least a second pressure sensor. An inlet of the first flow sensor is adapted for coupling to a gas supply. A control valve is coupled to an outlet of the flow sensor. The first pressure sensor is adapted to sense a metric indicative of the pressure upstream of the first flow sensor. The second pressure sensor is adapted to sense a metric indicative of the pressure downstream of the control valve.

1 . Apparatus for gas control, comprising: 
 at least a first flow sensor having an inlet adapted for coupling to a gas supply by a first gas line;    a control valve;    a second gas line coupled to an outlet of the flow sensor and an inlet of the control valve;    a third gas line coupled to an outlet of the control valve;    a upstream pressure sensor coupled to the first gas line and adapted to sense a metric indicative of pressure within the first gas line; and    a downstream pressure sensor coupled to the third gas line and adapted to sense a metric indicative of pressure within the third gas line.    
   
   
       2 . The apparatus of  claim 1  further comprising: 
 a bypass line coupled to the third gas line.    
   
   
       3 . The apparatus of  claim 2 , wherein the bypass line further comprises: 
 a restrictor sized such that flow is choked and proportional to the downstream pressure sensor; and    a bypass valve coupled in parallel.    
   
   
       4 . The apparatus of  claim 3  further comprising: 
 a vacuum source coupled in parallel to outlets of the restrictor and bypass valve.    
   
   
       5 . The apparatus of  claim 4 , wherein the vacuum source provides a pressure at least 2 times less than a pressure in the third gas line.  
   
   
       6 . The apparatus of  claim 1  further comprising: 
 an intermediate pressure sensor adapted to provide a metric of pressure in the second gas line, wherein a flow of gas passing through the second gas line may be expressed as:              F   A     =       F   S     +       F     Δ   ⁢           ⁢     P   S         ⁡     (         ⅆ     P   S         ⅆ   t       ,     V   s       )       -       F   P     ⁡     (       ⅆ   P       ⅆ   t       )                 where:    F S  is the flow sensed by the flow sensor;    P is the pressure sensed in the first gas line;    P S  is the pressure sensed in the second gas line; and    V S  is the volume between flow sensor and the control valve in the second gas line.    
   
   
       7 . The apparatus of  claim 6  further comprising: 
 a bypass control branch teed to the third gas line and having a bypass restrictor;    a bypass valve coupled in parallel to the bypass restrictor; and    a vacuum source coupled in parallel to outlets of the bypass restrictor and the bypass valve.    
   
   
       8 . The apparatus of  claim 1  further comprising: 
 an intermediate pressure sensor coupled to the second gas line and adapted to sense a metric indicative of pressure within the second gas line and;    
   
   
       9 . The apparatus of  claim 8 , wherein a flow of gas passing through an outlet of the apparatus downstream of the downstream pressure sensor may be expressed as:  
         F   W   =F   A   −F   BLEED ( P   W )  
     where: 
 F A  is the flow measured by the flow sensor;  
 F BLEED  is the flow to the vacuum source; and  
 P W  is the pressure sensed in the third gas line  
 
   
   
       10 . The apparatus of  claim 9 , wherein the flow of gas to the vacuum source is at least one of measured or factory calibrated.  
   
   
       11 . The apparatus of  claim 2 , wherein the bypass line is disposed downstream of the downstream pressure sensor.  
   
   
       12 . The apparatus of  claim 2  further comprising: 
 a bypass pressure sensor coupled to the bypass control branch and adapted to sense a metric indicative of pressure within the bypass control branch.    
   
   
       13 . The apparatus of  claim 1 , wherein the third gas line is coupled to a processing chamber.  
   
   
       14 . The apparatus of  claim 16 , wherein the third gas line is routed through a substrate support disposed in the processing chamber.  
   
   
       15 . The apparatus of  claim 1 , wherein the control valve, the flow sensor, and up to three pressure sensors define a first sub-circuit having a first gas outlet; and 
 a second sub-circuit configured substantially identical to the first sub-circuit and having a second gas outlet.    
   
   
       16 . The apparatus of  claim 15 , wherein the outlet of the first sub-circuit is coupled to a first substrate support and the outlet of the second sub-circuit is coupled to a second substrate support.  
   
   
       17 . The apparatus of  claim 16 , wherein the first substrate support is disposed in a different processing chamber than the second substrate support.  
   
   
       18 . The apparatus of  claim 16 , wherein the outlet of the first sub-circuit is coupled to a first backside gas control zone of the first and second substrate supports; and 
 the outlet of the second sub-circuit is coupled to a second backside gas control zone of the first and second substrate supports.    
   
   
       19 . Apparatus for gas control, comprising: 
 at least a first control valve having an inlet adapted for coupling to a gas supply;    a flow sensor coupled to an outlet of the control valve;    a first gas line coupled to an outlet of the control valve and the inlet of the flow sensor;    a upstream pressure sensor couple to the first gas line and adapted to sense a metric indicative of pressure within the first gas line.    a second gas line coupled to an outlet of the flow sensor; and    a downstream pressure sensor coupled to the second gas line and adapted to sense a metric indicative of pressure within the second gas line.    
   
   
       20 . The apparatus of  claim 19  further comprising; 
 a restrictor disposed in the second gas line;    an intermediate pressure sensor coupled to the second gas line and adapted to sense a metric indicative of pressure within the second gas line upstream of the restrictor;    
   
   
       21 . The apparatus of  claim 19  further comprising: 
 a bypass line coupled to the second gas line down stream of the restrictor.    
   
   
       22 . The apparatus of  claim 21 , wherein the bypass line further comprises: 
 a bypass restrictor; and    a bypass valve coupled in parallel.    
   
   
       23 . The apparatus of  claim 22  further comprising: 
 a vacuum source coupled in parallel to outlets of the restrictor and bypass valve.    
   
   
       24 . The apparatus of  claim 23 , wherein the vacuum source provides a pressure at least 2 times less than a pressure in the second gas line.  
   
   
       25 . The apparatus of  claim 24  further comprising: 
 an intermediate pressure sensor adapted to provide a metric of pressure in the second gas line, wherein a flow of gas passing through the first gas line may be expressed as:              F   A     =       F   S     +       F     Δ   ⁢           ⁢     P   S         ⁡     (         ⅆ     P   S         ⅆ   t       ,     V   s       )       -     Fpu   ⁡     (         ⅆ   Pu       ⅆ   t       ,   Vu     )                 where:    F S  is the flow sensed by the flow sensor;    Pu is the pressure sensed in the first gas line;    Vu is the volume between the between the flow sensor and the control valve in the first gas line;    P S  is the pressure sensed in the second gas line; and    V S  is the volume between flow in the second gas line.    
   
   
       26 . The apparatus of  claim 25  further comprising: 
 a bypass control branch teed to the second gas line;    a bypass restrictor;    a bypass valve coupled in parallel to the bypass restrictor; and    a vacuum source coupled in parallel to outlets of the bypass restrictor and bypass valve.    
   
   
       27 . The apparatus of  claim 26 , wherein a flow of gas passing through an outlet of the apparatus teed to the second gas line and bypass line may be expressed as:  
         F   W   =F   A   −F   BLEED ( P   W )  
     where: 
 F A  is the flow measured by the flow sensor; and  
 F BLEED  is the flow to the vacuum source.  
 
   
   
       28 . The apparatus of  claim 27 , wherein the flow of gas to the vacuum source is at least one of measured or factory calibrated.  
   
   
       29 . The apparatus of  claim 27  further comprising: 
 a restrictor disposed in the second gas line; and    an intermediate pressure sensor coupled to the second gas line and adapted to sense a metric indicative of pressure within the second gas line upstream of the restrictor.    
   
   
       30 . The apparatus of  claim 22  further comprising an outlet gas line.  
   
   
       31 . The apparatus of  claim 30 , wherein the outlet gas line is coupled to a processing chamber.  
   
   
       32 . The apparatus of  claim 19 , wherein the control valve, the flow sensor, the upstream pressure sensor and the downstream pressure sensor define a first sub-circuit having a first gas outlet; and 
 a second sub-circuit configured substantially identical to the first sub-circuit and having a second gas outlet.    
   
   
       33 . The apparatus of  claim 32 , wherein the outlet of the first sub-circuit is coupled to a first substrate support and the outlet of the second sub-circuit is coupled to a second substrate support.  
   
   
       34 . The apparatus of  claim 32 , wherein the first substrate support is disposed in a different processing chamber than the second substrate support.  
   
   
       35 . The apparatus of  claim 33 , wherein the outlet of the first sub-circuit is coupled to a first backside gas control zone of the first and second substrate supports; and 
 the outlet of the second sub-circuit is coupled to a second backside gas control zone of the first and second substrate supports.    
   
   
       36 . The apparatus of  claim 19  further comprising: 
 a restrictor disposed between the second and downstream pressure sensor.    
   
   
       37 . The apparatus of  claim 19  further comprising: 
 a bypass control branch teed between the control valve and the flow sensor;    a bypass restrictor;    a bypass valve coupled in parallel to the bypass restrictor; and    a vacuum source coupled in parallel to outlets of the bypass restrictor and bypass valve.