Symmetric precursor delivery

Abstract

A gas delivery system for a processing chamber includes a first channel for delivering a first chemistry and a second channel for delivering a second chemistry. The first channel includes a first outlet valve and the second channel includes a second outlet valve. A trickle gas source is connected to both the first and the second channels. A first junction is coupled to the first outlet valve and a second junction is connected to the second outlet valve. A common conduit connects between the first junction and the second junction. The first junction includes an input to provide a push gas from a push gas source and the second junction includes an output to a processing chamber. During operation, one of the first channel or the second channel is active at one time. A trickle gas from a trickle gas source is flowed into an active one and a non-active one of the first or second channels. A push inert gas from the push gas source is flowed into the first junction, through the common conduit and out of the second junction to the processing chamber.

1 . A gas delivery system for a processing chamber, comprising,
 a first channel for delivering a first chemistry to the processing chamber, the first channel having a first inlet valve coupled to a first chemistry source, a first trickle inlet valve coupled to a trickle gas source, and a first outlet valve,   a second channel for delivering a second chemistry to the processing chamber, the second channel having a second inlet valve coupled to a second chemistry source, a second trickle inlet valve coupled to the trickle gas source, and a second outlet valve; and   a common conduit coupled to the first outlet valve at a first junction and to the second outlet valve at a second junction;   wherein, during operation,
 (a) only one of the first inlet valve or the second inlet valve is kept open to allow the first chemistry or the second chemistry to flow toward the processing chamber, and 
 (b) both of the first trickle inlet valve and the second trickle inlet valve are kept open to allow the trickle inert gas to flow through the common conduit toward the processing chamber. 
   
     
     
         2 . The gas delivery system of  claim 1 , wherein the first junction is coupled to a push gas source to allow push inert gas to flow through the first and second junctions of the common conduit toward the processing chamber. 
     
     
         3 . The gas delivery system of  claim 2 , wherein the push gas source is kept on to allow the push inert gas to flow through the first and the second junctions, during operation of the gas delivery system. 
     
     
         4 . The gas delivery system of  claim 1 , wherein the first and the second channels are coupled to a controller, the controller configured to provide signals to control operation of the first and the second channels. 
     
     
         5 . The gas delivery system of  claim 1 , wherein the first channel includes a first ampoule with a first inlet for receiving the first chemistry from the first chemistry source and a first trickle inlet to receive the trickle inert gas from the trickle gas source, and
 wherein the second channel includes a second ampoule with a second inlet for receiving the second chemistry from the second chemistry source and a second trickle inlet to receive the trickle inert gas from the trickle gas source.   
     
     
         6 . The gas delivery system of  claim 5 , wherein the first inlet valve of the first channel is configured to regulate flow of the first chemistry from the first chemistry source into the first ampoule, and
 wherein the second inlet valve of the second channel is configured to regulate flow of the second chemistry from the second chemistry source into the second ampoule.   
     
     
         7 . The gas delivery system of  claim 5 , wherein the first channel includes a first trickle control to regulate flow of the trickle inert gas from the trickle gas source to the first ampoule, and the second channel includes a second trickle control to regulate flow of the trickle inert gas from the trickle gas source to the second ampoule. 
     
     
         8 . The gas delivery system of  claim 5 , wherein the first and the second ampoules each includes a spill detector valve and one or more level sensors coupled to the spill detector valve, the one or more level sensors of the first channel or the second channel that is kept open, are configured to generate a signal to the corresponding spill detector valve indicative of a level of the first or the second chemistries in the corresponding first or the second ampoules,
 the spill detector valve coupled to a controller configured to control flow of the first or the second chemistries to the corresponding first or second ampoules.   
     
     
         9 . The gas delivery system of  claim 5 , wherein components of each of the first and the second channels are symmetrically located in relation to each other within the gas delivery system. 
     
     
         10 . The gas delivery system of  claim 1 , wherein a layout of the first channel matches a layout of the second channel,
 the layout is defined by a total line length, a number of bends, a line width, and a number of fittings of a conduit in the respective one of the first and second channels, and   wherein the total line length of the conduit is computed as a sum of length of each line segment, wherein a line segment is defined between consecutive pair of bends, and   wherein matching the layout of the conduit of the first channel to the conduit of the second channel includes matching the total line lengths, the number of fittings, the number of bends and the line width.   
     
     
         11 . The gas delivery system of  claim 10 , wherein the total line length of the conduit of the first channel includes a length of a line segment of the common conduit between the first junction and the second junction. 
     
     
         12 . The gas delivery system of  claim 1 , wherein a length of the common conduit between the first junction and the second junction is defined to avoid diffusion of the first or the second chemistries into one of the first or second channels that is kept closed, wherein the length is derived as a Peclet number. 
     
     
         13 . The gas delivery system of  claim 1 , wherein the trickle inert gas is Argon. 
     
     
         14 . A gas delivery system for a processing chamber, comprising:
 a first channel for delivering a first chemistry to the processing chamber, the first channel includes a first ampoule with a first inlet controlled by a first inlet valve coupled to a first chemistry source and a first trickle inlet controlled by a first trickle inlet valve coupled to a trickle gas source, the first channel further includes a first outlet valve;   a second channel for delivering a second chemistry to the processing chamber, the second channel includes a second ampoule with a second inlet controlled by a second inlet valve coupled to a second chemistry source and a second trickle inlet controlled by a second trickle inlet valve coupled to the trickle gas source, the second channel further includes a second outlet valve; and   a common conduit coupled to the first outlet valve at a first junction and to the second outlet valve at a second junction;   wherein, during operation,
 (a) only one of the first inlet valve or the second inlet valve is kept open to allow the first chemistry or the second chemistry to flow toward the processing chamber, and 
 (b) both of the first trickle inlet valve and the second trickle inlet valve are kept open to allow the trickle inert gas to flow through the common conduit toward the processing chamber. 
   
     
     
         15 . The gas delivery system of  claim 14 , wherein the first inlet valve of the first channel is configured to regulate flow of the first chemistry from the first chemistry source into the first ampoule,
 wherein the second inlet valve of the second channel is configured to regulate flow of the second chemistry from the second chemistry source into the second ampoule,   wherein the first channel includes a first trickle control to regulate flow of the trickle inert gas from the trickle gas source to the first ampoule, and the second channel includes a second trickle control to regulate flow of the trickle inert gas from the trickle gas source to the second ampoule.   
     
     
         16 . The gas delivery system of  claim 14 , wherein each of the first and the second ampoules includes one or more level sensors coupled to a spill detector valve, the one or more level sensors of the first or the second channel that is kept open, are configured to generate a signal to the spill detector valve indicative of a level of the first or the second chemistries in the first or the second ampoules,
 wherein the spill detector valve is configured to control flow of the first or the second chemistries into the corresponding first or second ampoules.   
     
     
         17 . The gas delivery system of  claim 14 , further includes a manometer coupled to each of the first and the second ampoules, the manometer configured to control pressure of the first or the second chemistries flowing from the first or the second ampoules toward the first or second outlet valves. 
     
     
         18 . The gas delivery system of  claim 14 , wherein the first channel includes a first conduit connecting the first ampoule to the first junction, and the second channel includes a second conduit connecting the second ampoule to the second junction, a layout of the first conduit of the first channel matches a layout of the second conduit of the second channel,
 wherein the layout of each of the first conduit and the second conduit is defined by a total line length, a number of bends, a line width, and a number of fittings, the total line length computed as a sum of length of line segments of each conduit, wherein each line segment is defined between consecutive pair of bends, and   wherein matching the layout of the conduit of the first channel to the layout of the conduit of the second channel includes matching the total line length, the number of fittings, the number of bends and the line width.   
     
     
         19 . The gas delivery system of  claim 14 , wherein the first inlet valve and the first trickle inlet valve of the first channel and the second inlet valve and the second trickle inlet valve of the second channel are coupled to a controller, the controller configured to provide signals to control flow of the first chemistry, trickle inert gas into the first ampoule, and the second chemistry, the trickle inert gas into the second ampoule. 
     
     
         20 . The gas delivery system of  claim 14 , wherein the first junction is coupled to a push gas source to allow push inert gas to flow through the first and the second junctions of the common conduit toward the processing chamber,
 wherein the push gas source is kept on during operation of the gas delivery system to allow the push inert gas to flow through the first and the second junctions toward the processing chamber.