METHOD FOR METERING GRANULAR SOURCE MATERIAL IN A THIN FILM VAPOR DEPOSITION APPARATUS
A method is provided for continuously feeding source material from a bulk supply at atmospheric conditions to a vapor deposition apparatus while maintaining vacuum deposition conditions in the vapor deposition apparatus. The method includes sequentially conveying doses of granular source material from a bulk supply into a vacuum lock chamber. For each dose, a vacuum is drawn in the chamber and the dose of source material is transferred to a downstream transfer mechanism prior to introduction of a subsequent dose of source material into the vacuum lock chamber. The source material is transferred from the transfer mechanism to a downstream deposition head while maintaining the vacuum deposition conditions within the deposition head and blocking upstream diffusion of sublimated source material through the transfer mechanism.
1 . A method for continuously feeding source material from a bulk supply at atmospheric conditions to a vapor deposition apparatus while maintaining vacuum deposition conditions in the vapor deposition apparatus, the method comprising:
sequentially conveying doses of granular source material from a bulk supply into a vacuum lock chamber;
drawing a vacuum in the vacuum lock chamber and transferring each dose of source material from the vacuum lock chamber to a downstream transfer mechanism prior to introduction of a subsequent dose of source material into the vacuum lock chamber; and
transferring the source material from the transfer mechanism to a downstream deposition head while maintaining the vacuum deposition conditions within the deposition head and blocking upstream diffusion of sublimated source material through the transfer mechanism.
2 . The method as in claim 1 , further comprising metering the source material between the vacuum lock chamber and the transfer mechanism such that the dose amount of source material delivered to the transfer mechanism is different than the dose amount of source material delivered from the vacuum lock chamber.
3 . The method as in claim 1 , wherein the source material is metered with a reciprocating delivery member having a passage defined therethrough, wherein the metered flow rate of the source material is controlled by controlling the reciprocating rate of the delivery member.
4 . The method as in claim 1 , wherein the source material is conveyed from the bulk supply to an actuatable receptacle disposed within the vacuum lock chamber, wherein the receptacle is controlled to dump the source material by gravity to a downstream metering position at a defined vacuum condition.
5 . The method as in claim 4 , wherein the source material is received by a metering mechanism at the downstream metering position.
6 . The method as in claim 5 , wherein the source material is metered at the metering mechanism with a reciprocating delivery member having a passage defined therethrough, wherein the metered flow rate of the source material is controlled by controlling the reciprocating rate of the delivery member.
7 . The method as in claim 1 , wherein the source material from the bulk supply is sequentially formed into discrete measured doses that are conveyed into the vacuum lock chamber.
8 . The method as in claim 7 , wherein each measured dose of source material from the vacuum lock chamber is subsequently metered into discrete amounts that are sequentially supplied to the downstream transfer mechanism.
9 . The method as in claim 8 , wherein the source material is metered in a metering mechanism by a reciprocating delivery member having a passage defined therein, wherein the metered flow rate of the source material is controlled by controlling the reciprocating rate of the delivery member.
10 . The method as in claim 7 , wherein the transfer mechanism sequentially delivers the source material to the downstream deposition head.