Fluid-assisted thermal management of evaporation sources

Abstract

In various embodiments, evaporation sources for deposition systems are heated and/or cooled via a fluid-based thermal management system.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation of U.S. patent application Ser. No. 15 / 904,647, filed Feb. 26, 2018, which is a continuation of U.S. patent application Ser. No. 15 / 082,290, filed Mar. 28, 2016, which claims the benefit of and priority to U.S. Provisional Patent Application No. 62 / 140,083, filed Mar. 30, 2015, the entire disclosure of each of which is hereby incorporated herein by reference.TECHNICAL FIELD[0002]In various embodiments, the present invention relates to thermal evaporation, in particular to thermal management of evaporation sources.BACKGROUND OF THE INVENTION[0003]Thermal evaporation is a well-known approach to forming a number of materials such as III-V solid-state semiconductors via molecular beam epitaxial (MBE) growth. Another commercial application of this technique is the evaporation of aluminum (Al) onto polymer foils for the packaging industry or other metals onto polymer foils for capacitor manufacturing. In these...

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Benefits of technology

[0006]Conventional systems with high thermal mass have the added advantage that control of the thermal evaporation process is simplified as temperature fluctuations based on power fluctuations to the heaters are typically negligible. Highly effective thermal insulation further reduces sensitivity to incoming power fluctuations. Such thermal insulation also reduces heat losses to the surroundings, i.e., it increases thermal coupling efficiency of the electrical heater power to the material to be evaporated, leading to lower operating costs. In summary, high thermal mass and highly effective thermal insulation are important aspects of conventional industrial thermal evaporation processes.

Problems solved by technology

However, this process starts to lose effectiveness the lower the temperature of the body to be cooled and the smaller the temperature difference between the body cooling down and the system absorbing the thermal energy.

Thus, in a vacuum environment, cooling via radiation is typically most effective above approximately 300° C. Similarly, coupling heat into evaporation sources operating at low temperatures (e.g., <400° C.) via radiation is also less effective, in particular if the material is one with poor thermal conductivity (e.g., P, S, or Se).

Such concerns complicate both the reservoir and resistive heater design, as well as thermal evaporation rate control of these high-vapor-pressure elements.

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