Control of gas flow and delivery to suppress the formation of particles in an MOCVD/ALD system

Abstract

The embodiments of the invention describe a process chamber, such as an ALD chamber, that has gas delivery conduits with gradually increasing diameters to reduce Joule-Thompson effect during gas delivery, a ring-shaped gas liner leveled with the substrate support to sustain gas temperature and to reduce gas flow to the substrate support backside, and a gas reservoir to allow controlled delivery of process gas. The gas conduits with gradually increasing diameters, the ring-shaped gas liner, and the gas reservoir help keep the gas temperature stable and reduce the creation of particles.

1 . A gas delivery assembly, comprising: 
 a covering member comprising an expanding channel at a central portion of the covering member which comprises a bottom surface extending from the expanding channel to a peripheral portion of the covering member; and    at least one gas conduit having a first end, with a first diameter, connected to a gas inlet of the expanding channel, and a second end, with a second diameter, connected to a valve, wherein the second diameter is greater than the first diameter and the diameter of the at least one gas conduit gradually and continuously increases from the second diameter to the first diameter, and the at least one gas conduit is positioned at an angle from a center of the expanding channel.    
   
   
       2 . The gas delivery assembly of  claim 1 , wherein the at least one gas conduit is disposed normal to a longitudinal axis of the expanding channel.  
   
   
       3 . The gas delivery assembly of  claim 1 , wherein the at least one gas conduit is disposed at an angle to a longitudinal axis of the expanding channel.  
   
   
       4 . The gas delivery assembly of  claim 1 , wherein the at least one gas conduit is disposed at the same length around the expanding channel.  
   
   
       5 . The gas delivery assembly of  claim 1 , wherein the expanding channel comprises a tapered surface extending from the central portion of the covering member.  
   
   
       6 . The gas delivery assembly of  claim 1 , wherein there are four gas conduits connected to four gas inlets of the process chamber.  
   
   
       7 . An ALD process chamber, comprising: 
 a ring-shaped gas liner placed between the substrate support and between the chamber wall, wherein the top surface of the ring-shaped liner is at the same level as the substrate support during exhaust gas being pumped out the process chamber.    
   
   
       8 . The ALD process chamber of  claim 7 , wherein the liner is made of aluminum, quartz, or pyrolitic boron nitride.  
   
   
       9 . An ALD process chamber, comprising: 
 at least one reservoir to store one process gas, wherein the first end of the at least one reservoir is coupled to a gas valve that connects to a gas conduit with a length between about 3 cm to about 10 cm connecting a gas inlet of the process chamber and the second end of the at least one reservoir couples to a gas source, and the diameter of the first end of the at least one reservoir gradually and continuously reduces to the diameter of an inlet of the gas valve and the diameter of the second end of the at least one reservoir gradually and continuously reduces to a diameter of a gas line that connects with the gas source.    
   
   
       10 . The ALD process chamber of  claim 9 , wherein there are four reservoirs coupled to the ALD process chamber.  
   
   
       11 . An ALD process chamber, comprising: 
 a covering member comprising an expanding channel at a central portion of the covering member which comprises a bottom surface extending from the expanding channel to a peripheral portion of the covering member;    at least one gas conduit having a first end, with a first diameter, connected to a gas inlet of the expanding channel, and a second end, with a second diameter, connected to a gas valve, wherein the second diameter is greater than the first diameter and the diameter of the at least one gas conduit gradually and continuously increases from the second diameter to the first diameter, and the at least one gas conduit is positioned at an angle from a center of the expanding channel; and    at least one reservoir to store one process gas, wherein the first end of the at least one reservoir is coupled to the gas valve that connects to the at least one gas conduit and the second end of the at least one reservoir couples to a gas source, and the diameter of the first end of the at least one reservoir gradually and continuously reduces to a third diameter of an inlet of the gas valve and the diameter of the second end of the at least one reservoir gradually and continuously reduces to a fourth diameter of a gas line that connects with the gas source.    
   
   
       12 . The ALD process chamber of  claim 11 , wherein the at least one gas conduit is disposed normal to a longitudinal axis of the expanding channel.  
   
   
       13 . The ALD process chamber of  claim 11 , wherein the at least one gas conduit is disposed at the same length around the expanding channel.  
   
   
       14 . The ALD process chamber of  claim 11 , wherein the expanding channel comprises a tapered surface extending from the central portion of the covering member.  
   
   
       15 . The process chamber of  claim 11 , wherein there are four reservoirs connected to four gas valves and the four gas valves connects to four gas conduits respectively.  
   
   
       16 . The ALD process chamber of  claim 15 , wherein the four gas conduits are equally spaced out around a perimeter of the expanding channel.  
   
   
       17 . The ALD process chamber of  claim 15 , wherein the four gas conduits are positioned around the same circular direction.  
   
   
       18 . A method of delivering gases to a substrate in a substrate processing chamber, comprising: 
 providing at least one gas into the substrate processing chamber from a reservoir wherein the first end of the reservoir is coupled to a gas valve that connects to a gas conduit, wherein the gas conduit having a first end, with a first diameter, connected to a gas inlet of a expanding channel of the substrate processing chamber, and a second end, with a second diameter, connected to the gas valve, wherein the second diameter is greater than the first diameter and the diameter of the gas conduit gradually and continuously increases from the second diameter to the first diameter, and the gas conduit is positioned at an angle from a center of the expanding channel, and the second end of the reservoir couples to a gas source, and the diameter of the first end of the reservoir gradually and continuously reduces to a third diameter of an inlet of the gas valve and the diameter of the second end of the reservoir gradually and continuously reduces to a fourth diameter of a gas line that connects with the gas source; and    providing the gases to a central portion of the substrate.    
   
   
       19 . The method of  claim 18 , wherein providing at least one gas into the chamber comprises directing the gases in an initial circular direction over a central portion of the substrate.  
   
   
       20 . The method of  claim 18 , wherein the temperature of the at least one gas is maintained at above 150° C. throughout the gas delivery process.