Fluid-Assisted Evaporation Source Cooling for Faster Thermal Cycling

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Solution Overview

Problem

Thermal evaporation processes face challenges with materials like phosphorous, sulfur, and selenium due to their poor heat capacity and thermal conductivity, leading to difficulties in controlling evaporation rates and requiring long heat-up and cool-down times, which increases manufacturing costs and reduces throughput.

Innovation Solution

The implementation of a heat-transfer fluid system for thermal management, which supplements or replaces traditional heating and cooling methods, allowing for rapid temperature control and efficient heat transfer, utilizing separate or combined heating and cooling loops with a heat exchanger to regulate the temperature and flow rate of the fluid.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If conventional thermal evaporation sources with high thermal mass are used, then temperature control stability is improved, but heat-up and cool-down times increase significantly

Engineering Contradiction:

Improvetemperature control stabilityVSAvoidheat-up and cool-down times

Core Design Contradiction:

Stability of the object's compositionVSLoss of time

Solution Approach 1:

The thermal management system is segmented into separate heating and cooling subsystems. The cooling subsystem includes a cooling element with cooling channels that can be independently controlled from the heating element, allowing simultaneous or independent operation of heating and cooling functions to reduce total cycle time

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The cooling element is pre-positioned and pre-configured within the evaporation source structure before the deposition cycle begins. The cooling channels are pre-filled with coolant, and the cooling system is pre-cooled, so that cooling can begin immediately when needed without waiting for system preparation

Inventive Principle:

Principle #10Preliminary action

2Stability of the object's composition

If materials with poor thermal conductivity are used, then evaporation rate control becomes difficult, but the ability to maintain stable vapor pressure improves

Engineering Contradiction:

Improvevapor pressure stabilityVSAvoidevaporation rate control

Core Design Contradiction:

Stability of the object's compositionVSEase of operation

Solution Approach 1:

A thermal management fluid (coolant) is introduced as an intermediary substance that circulates through cooling channels in contact with the source material or source container. This fluid acts as a heat transfer mediator, allowing precise control of heat removal from the source, thereby enabling better evaporation rate control while maintaining vapor pressure stability

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces direct mechanical or electrical heating control with a fluid-based thermal management system. Instead of directly controlling heater power to achieve evaporation rate control, the system uses coolant flow rate and temperature control to indirectly regulate the source temperature and thus the evaporation rate, providing smoother and more precise control

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If continuous feed of source material is implemented, then throughput is improved, but system complexity and cost increase

Engineering Contradiction:

ImprovethroughputVSAvoidsystem complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The system uses the thermal energy already present in the evaporated material and the thermal management system itself to maintain continuous operation. The cooling system continuously removes heat, enabling the source to maintain stable temperature and continuous evaporation without requiring complex external intervention or material replenishment mechanisms

Inventive Principle:

Principle #25Self-service

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enables faster cooling and higher turnaround times between deposition cycles, reducing manufacturing costs and improving throughput by effectively managing thermal energy transfer for materials with poor thermal conductivity and high vapor pressure/temperature dependence.

Implementation Method 1

fluid-based thermal management is utilized only for heating (or additional heating), while in other embodiments, heat-transfer fluid is utilized only for cooling (or additional cooling)

Methodology Applied

Scientific EffectHeat transfer: Convection

Implementation Method 2

utilizing separate or combined heating and cooling loops with a heat exchanger to regulate the temperature and flow rate of the fluid

Methodology Applied

Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 3

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

Methodology Applied

Scientific EffectThermal evaporation: Evaporation

Data Source

PatentUS9932666B2Fluid-assisted thermal management of evaporation sources

Publication Date: 2018.04.03 FIRST SOLAR INC

AI summary

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