METHOD AND APPARATUS
Disclosed is a method of providing a constant concentration of a metal-containing precursor compound in the vapor phase in a carrier gas. Such method is particularly useful in supplying a constant concentration of a gaseous metal-containing compound to a plurality of vapor deposition reactors.
1 . An apparatus for delivering a substantially constant concentration of a vaporized precursor compound in a carrier gas to a plurality of vapor deposition reactors, comprising: an evaporation vessel comprising a chamber containing a precursor compound to be vaporized, the evaporation vessel having a gas inlet and a gas outlet, a carrier gas feed line in fluid communication with the gas inlet, and a gas exit line in fluid communication between the gas outlet and a plurality of vapor deposition reactors; a gas control means in the carrier gas feed line; a sensing means in the gas exit line for sensing a concentration of the vaporized precursor compound in the gaseous mixture in the gas exit line; means for comparing the sensed concentration (c) with a reference concentration (c o ) to provide a concentration differential (c−c o ); signal generating means for generating a signal in a controller utilizing the concentration differential; and a means for transmitting the signal to the gas control means wherein the signal adjusts the gas control means to adjust total pressure in the evaporation vessel in order to maintain a substantially constant concentration of the vaporized precursor compound in the gaseous mixture in the gas exit line.
2 . The apparatus of claim 1 wherein a second gas control valve is present in the gas exit line.
3 . The apparatus of claim 1 wherein the gas exit line further comprises a pressure release valve.
4 . The apparatus of claim 1 wherein the sensing means in the gas exit line for sensing concentration is an acoustic concentration transducer.
5 . The apparatus of claim 1 wherein the gas exit line further comprises a pressure transducer.
7 . An apparatus for delivering a substantially constant concentration of a vaporized precursor compound in a carrier gas to a plurality of vapor deposition reactors, comprising: an evaporation vessel comprising a chamber containing a precursor compound to be vaporized, the evaporation vessel having a gas inlet and a gas outlet, a carrier gas feed line in fluid communication with the gas inlet, a gas exit line in fluid communication between the gas outlet and a plurality of vapor deposition reactors, and a temperature sensing means situated within the evaporation vessel so as to sense temperature of precursor compound; means for comparing the sensed temperature (T) with a reference temperature (T o ) to provide a temperature differential (T−T o ); a gas control means in the carrier gas feed line; means for generating a signal in a pressure controller utilizing the temperature differential; and a means for transmitting the signal to the gas control means wherein the signal adjusts the gas control means to adjust total pressure in the evaporation vessel in order to maintain a substantially constant concentration of the vaporized precursor compound in the gaseous mixture in the gas exit line.
7 . The apparatus of claim 6 wherein a second gas control valve is present in the gas exit line.
8 . The apparatus of claim 6 wherein the gas exit line further comprises a pressure transducer.
9 . The apparatus of claim 6 wherein the gas exit line further comprises a pressure release valve.
10 . The apparatus of claim 6 wherein the gas exit line comprises a sensing means in the gas exit line for sensing a concentration of the vaporized precursor compound in the gaseous mixture in the gas exit line.