Gas supply device for precursors with a low vapor pressure

Abstract

The invention relates to a gas supply device for delivering precursors with a low vapor pressure to CVD coating systems. Said gas supply device has a supply container for the precursor which is at a first temperature T 1 , an intermediate storage device for intermediately storing the vaporous precursor at a second temperature T 2 and at a constant pressure p 2 , a first gas line between the supply container and the intermediate storage device and a second gas line for removing gas from the intermediate storage device. According to the invention, the gas supply device is developed in such a way that the first temperature T 1 is higher than the second temperature T 2 . The lower temperature T 2 of the intermediate storage device facilitates maintenance work on the same, while the precursor evaporates at a greater rate at the higher temperature T 1 in the supply container. According to a particularly advantageous embodiment, a first precursor vapor is mixed with a gas and/or a second precursor vapor in the intermediate storage device. The partial pressure of the first precursor vapor in the intermediate storage device is lower than that of the undiluted first precursor vapor at a constant overall pressure in said intermediate storage device, so that the temperature T 2 of the intermediate storage device and the successive lines can be reduced. Reducing the temperature T 2 allows less expensive components to be used.

1 . Gas supply device for precursors with a low vapor pressure, especially for CVD coating systems, with a supply container ( 2 ) for a first precursor with a low vapor pressure, where the supply container ( 2 ) with the precursor is maintained at a first temperature T 1 , with an intermediate storage device ( 4 ) for intermediate storage of the vaporous first precursor, where the intermediate storage device ( 4 ) is maintained at a second temperature T 2  and at a constant pressure p 2  which is lower than a pressure p 1  in the supply container ( 2 ), with a first gas line ( 3 ) between the supply container ( 2 ) and the intermediate storage device ( 4 ), and with a second gas line ( 10 ) on the intermediate storage device ( 4 ) for removing gas from the intermediate storage device ( 4 ), characterized in that the first temperature T 1  is higher than the second temperature T 2 .  
     
     
         2 . Gas supply device as defined in  claim 1 , characterized in that the temperature T 2  in the intermediate storage device ( 4 ) is set such that the saturation vapor pressure of the first precursor is higher than its partial pressure in the intermediate storage device ( 4 ).  
     
     
         3 . Gas supply device as defined in  claim 1  or  2 , characterized in that the pressure p 1  of the first precursor in the supply container ( 2 ) is the saturation vapor pressure and the first precursor is in equilibrium between the liquid or solid phase and the vaporous phase.  
     
     
         4 . Gas supply device as defined in  claim 3 , characterized in that the temperature T 1  of the supply container ( 2 ) is set such that the pressure p 1  of the first precursor in the supply container ( 2 ) is between 1.5 and 10 times higher than the pressure p 2 .  
     
     
         5 . Gas supply device as defined in  claim 4 , characterized in that the pressure p 1  is approximately twice as high as the pressure p 2 .  
     
     
         6 . Gas supply device as defined in any of the preceding  claims 1  to  5 , characterized in that between the supply container ( 2 ) and the intermediate storage device ( 4 ) a first metering device ( 6 ) is disposed for adjusting the mass flow from the supply container ( 2 ) to the intermediate storage device ( 4 ).  
     
     
         7 . Gas supply device as defined in  claim 6 , characterized in that the first metering device ( 6 ) is a controllable mass flow controller.  
     
     
         8 . Gas supply device as defined in any of the  claims 1  to  7 , characterized in that the intermediate storage device ( 4 ) is coupled to a gas outlet via a second metering device ( 15 ).  
     
     
         9 . Gas supply device as defined in  claim 8 , characterized in that the second metering device ( 15 ) is a flow control valve.  
     
     
         10 . Gas supply device as defined in  claim 8  or  9 , characterized in that the gas outlet is connected to a vacuum pump ( 8 ) and/or cold trap.  
     
     
         11 . Gas supply device as defined in any of the  claims 8  to  10 , characterized in that the constant pressure p 2  in the intermediate storage device ( 4 ) is set by the second metering device ( 15 ).  
     
     
         12 . Gas supply device as defined in any of the  claims 1  to  11 , characterized in that a carrier gas can be delivered into the first gas line ( 3 ) between the supply container ( 2 ) and the intermediate storage device ( 4 ).  
     
     
         13 . Gas supply device as defined in any of the  claims 6  to  11 , characterized in that a carrier gas can be delivered into the first gas line ( 3 ) between the first metering device ( 6 ) and the intermediate storage device ( 4 ).  
     
     
         14 . Gas supply device as defined in  claim 12  or  13 , characterized in that the carrier gas is delivered via a third metering device ( 9 ).  
     
     
         15 . Gas supply device as defined in  claim 14 , characterized in that the third metering device ( 9 ) is a mass flow controller.  
     
     
         16 . Gas supply device as defined in any of the claims  14  or  15 , characterized in that the constant pressure p 2  is set by the mass flows of the first and third metering devices ( 6 ,  9 ) with a fixed cross-section of the opening of the second metering device ( 15 ).  
     
     
         17 . Gas supply device as defined in any of the  claims 12  to  16 , characterized in that the mass flow of the carrier gas is proportional to the mass flow of the first precursor from the supply container ( 2 ) to the intermediate storage device ( 4 ).  
     
     
         18 . Gas supply device as defined in any of the  claims 1  to  17 , characterized in that the precursor is an Nb, Ta, Ti or Al compound.  
     
     
         19 . Gas supply device as defined in  claim 18 , characterized in that the Nb compound is NbCl 5  or Nb ethoxide.  
     
     
         20 . Gas supply device as defined in  claim 18 , characterized in that the Ta compound is TaCl 5  or Ta ethoxide.  
     
     
         21 . Gas supply device as defined in  claim 18 , characterized in that the Al compound is AICl 3 .  
     
     
         22 . Gas supply device as defined in  claim 18 , characterized in that the Ti compound is TIPT (titanium isopropylate).  
     
     
         23 . Gas supply device as defined in any of the  claims 12  to  22 , characterized in that the carrier gas is an inert gas, a second precursor or a gas mix with a second precursor, where under normal conditions each of the carrier gases is gaseous.  
     
     
         24 . Gas supply device as defined in  claim 23 , characterized in that the carrier gas is or contains oxygen.