Delivery of liquid precursors to semiconductor processing reactors

Abstract

This invention relates to methods and apparatus for delivering liquid precursors to semi-conductor processing apparatus. The liquid precursor delivery system is generally indicated at 10 and includes a source 11, an inlet tube 12, a two-way valve 13, a pump assembly 14, an outlet tube 15, a shut-off valve 16 and a flash evaporator 17. The pump assembly 14 is in the form of a syringe or variable volume pump and is controlled by a combination of a step motor 27 and a linear encoder 30. The arrangement is such that unused liquid precursor can be returned to the source.

1 . Apparatus for delivering a liquid precursor to a semiconductor processing reactor including a source for the liquid precursor, a volume calibrated positive displacement pump for drawing liquid precursor from the source via an input path and for delivering along an output path a known volume of liquid precursor to the reactor.  
     
     
         2 . Apparatus as claimed in  claim 1  further including a valve for connecting the pump to the input path or the output path.  
     
     
         3 . Apparatus as claimed in  claim 2  further including control means for controlling the pump and valve whereby the pump draws liquid in, whilst the reactor is not processing with this precursor.  
     
     
         4 . Apparatus as claimed in  claim 2  or  claim 3  further including control means for controlling the pump and the valve whereby the pump returns some or all of the undelivered precursor to the source.  
     
     
         5 . Apparatus as claimed in any one of the preceding claims wherein the pump is a syringe pump.  
     
     
         6 . Apparatus as claimed in any of the preceding claims wherein the source includes a bottle or reservoir of liquid precursor.  
     
     
         7 . Apparatus as claimed in  claim 6  wherein the source includes at least two bottles or reservoirs and means for automatically connecting one bottle or reservoir to the inlet path as the other becomes empty.  
     
     
         8 . A method of delivering a liquid precursor to a semiconductor processing reactor including: 
 (i) Drawing a liquid precursor along an input path, into a volume calibrated positive displacement pump from a source of liquid precursor; and    (ii) Delivering, along an output path, a known volume of liquid precursor.    
     
     
         9 . A method as claimed in  claim 8  including alternately connecting the pump to the input path and the output path.  
     
     
         10 . A method as claimed in  claim 8  or  claim 9  wherein is after each volume delivery the pump returns some or all of the remaining liquid to the source, before drawing a fresh charge.