Evaporation vessel apparatus and method

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, a gas exit line in fluid communication between the gas outlet and the plurality of vapor deposition reactors, and a temperature sensing means situated within the evaporation vessel so as to sense temperature of the vaporized precursor compound; means for comparing the sensed temperature (T) with a reference temperature (To) to provide a temperature differential (T-To) of the vaporized precursor compound; wherein the means for comparing comprises a controller; a gas control means in the carrier gas feed line; wherein the gas control means comprises a gas control valve and the gas control valve is electrically connected to the controller; means for generating a signal in the controller utilizing the temperature differential; a means for transmitting the signal to the gas control means wherein the signal adjusts the gas control means to adjust a total pressure in the evaporation vessel in order to maintain the substantially constant concentration of the vaporized precursor compound in a gaseous mixture in the gas exit line; and with no mass flow transducer in the carrier gas feed line, wherein the gas exit line further comprises a pressure transducer and a concentration transducer; wherein the concentration transducer in the gas exit line senses a concentration of the vaporized precursor compound in the gaseous mixture in the gas exit line; wherein the pressure transducer and the concentration transducer are electrically connected to the controller and said controller is configured to maintain the substantially constant concentration of the vaporized precursor compound in the gaseous mixture in the gas exit line with steps selected from the group consisting of :

1) sensing a concentration of the vaporized precursor compound in the gaseous mixture with the concentration transducer in the gas exit line,

comparing the sensed concentration with a reference concentration to provide a concentration differential,

generating a signal in the controller utilizing the concentration differential,

transmitting the signal to the gas control valve wherein the signal is configured to adjust the gas control valve to adjust the total pressure within 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) sensing the temperature of the vaporized precursor compound within the evaporation vessel with the sensing means,

comparing the sensed temperature with a reference temperature to provide a temperature differential,

generating a signal in the controller utilizing the temperature differential,

transmitting the signal to the gas control valve wherein the signal adjusts the gas control valve to adjust the total pressure within 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; and (3) a combination of (1) and (2).

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 temperature sensing means comprises a temperature sensor, wherein the means for generating a signal comprises the controller, and wherein the means for transmitting the signal comprises the controller.