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Evaporation Apparatus

IP.com Disclosure Number: IPCOM000076232D
Original Publication Date: 1972-Feb-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 86K

Publishing Venue

IBM

Related People

Wald, G: AUTHOR [+2]

Abstract

Apparatus is provided for use in vacuum metal deposition. The apparatus permits strict control of the evaporation rate of a bulk source material, such as aluminum, copper or gold.

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Evaporation Apparatus

Apparatus is provided for use in vacuum metal deposition. The apparatus permits strict control of the evaporation rate of a bulk source material, such as aluminum, copper or gold.

In the vacuum deposition of relatively thin metallic films, it is critical that the evaporation rate of the source material be constant. If the pressure in the vacuum chamber is maintained constant and the surface area of the source cup is constant, the maintenance of a constant temperature will insure a constant evaporation rate. Referring to Fig. B, which is a partial section of Fig. A, the constant temperature in crucible 10 is maintained by positioning thermocouple 11 in the order of 0.05 inch from bottom 12 of reservoir 13 holding the molten metal to be evaporated. The proximity of the thermocouple to the molten metal permits the thermocouple to readily sense temperature variations and to transmit such sensed information to a control system (not shown), which varies the input to heater coils 14 for the modification necessary to maintain a constant temperature in the crucible or reservoir 13. The heater coils and the crucible base are enclosed within heat shields 15 which form the walls of housing 16.

The thermocouple is preferably a high-temperature thermocouple, e.g., presently available tungsten-rhenium thermocouples.

In a variation of the apparatus shown in Fig. C, in order to get a thermocouple reading as close as possible to the temperature of the molten...