SiC Ingot Growth via Layered Crucible Thermal Management

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Solution Overview

Problem

The sublimation method for producing SiC single crystal ingots faces challenges in achieving temperature uniformity and effective use of raw materials, particularly in larger-diameter and longer ingots, due to temperature distribution issues in the crucible, which limits growth rate and throughput.

Innovation Solution

A method involving a crucible configuration with a high thermal conductivity raw material layer and a low thermal conductivity raw material layer, disposed above or below the high thermal conductivity layer, to improve temperature uniformity and maximize heating to the high thermal conductivity layer, enhancing growth rate and material utilization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the crucible is heated from the side wall to grow larger-diameter and longer SiC ingots, then the ingot size increases, but temperature distribution in the crucible worsens causing crystallization at the central part

Engineering Contradiction:

Improveingot sizeVSAvoidtemperature uniformity

Core Design Contradiction:

Volume of moving objectVSTemperature

Solution Approach 1:

The patent applies local quality by creating a temperature uniformity improvement region specifically at the central part of the crucible bottom where raw material is disposed. By heating this specific local region to 2000°C or higher, the patent addresses the temperature non-uniformity problem without changing the overall heating approach, thereby maintaining the ability to grow large-diameter ingots while preventing central crystallization.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent segments the heating process into two distinct parts: (1) conventional side wall heating for overall temperature maintenance and (2) additional localized heating at the crucible bottom center. This segmentation allows each heating zone to perform its specific function - the side wall heating maintains general thermal conditions while the localized bottom heating ensures temperature uniformity in the raw material region.

Inventive Principle:

Principle #1Segmentation

2Productivity

If heating is intensified to increase growth rate, then productivity improves, but temperature distribution becomes more non-uniform causing raw material crystallization

Engineering Contradiction:

Improvegrowth rateVSAvoidraw material utilization

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent implements feedback control by monitoring the temperature at the central part of the crucible bottom and adjusting the heating power accordingly. The control unit maintains the temperature at 2000°C or higher, ensuring that the raw material region receives sufficient heat for effective sublimation and growth without causing unwanted crystallization, thus optimizing both growth rate and material utilization.

Inventive Principle:

Principle #23Feedback

3Productivity

If raw material is disposed only at the side of the crucible wall, then temperature distribution is simpler, but the growth amount and throughput are limited

Engineering Contradiction:

ImprovethroughputVSAvoidtemperature distribution

Core Design Contradiction:

ProductivityVSTemperature

Solution Approach 1:

The patent applies preliminary action by pre-heating the raw material at the central part of the crucible bottom to 2000°C or higher before the actual growth process begins. This pre-heating ensures that when the growth process starts, the raw material is already in the optimal temperature state for sublimation, enabling effective utilization of raw material disposed at the central region and increasing throughput.

Inventive Principle:

Principle #10Preliminary action

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 configuration improves temperature uniformity and allows for the effective use of raw materials, enabling the growth of high-quality SiC single crystal ingots with increased throughput.

Implementation Method 1

forming a raw material part by disposing a high thermal conductivity raw material layer and a low thermal conductivity raw material layer

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

performing heating so that the raw material part reaches the maximum temperature in the high thermal conductivity raw material layer

Methodology Applied

Scientific EffectHeating: Heating

Implementation Method 3

a sublimation gas sublimated from a raw material powder (raw material) in the crucible is supplied to the seed crystal, and the seed crystal grows into a larger SiC single crystal ingot

Methodology Applied

Scientific EffectSublimation: Sublimation

Implementation Method 4

there is a problem of a sublimation gas generated from the vicinity of the side of the crucible wall heated to a high temperature being crystallized at the central part at a low temperature

Methodology Applied

Scientific EffectCrystallization: Crystallisation

Data Source

PatentUS11761114B2Method of producing SiC single crystal ingot

Publication Date: 2023.09.19 RESONAC CORP

AI summary

In a method of producing a SiC single crystal ingot of the present invention, in a lower part of a crucible, a high thermal conductivity raw material layer containing a high thermal conductivity raw material and a low thermal conductivity raw material layer containing a low thermal conductivity raw material in at least one of a position above or below the high thermal conductivity raw material layer are disposed to form a raw material part, and heating is performed so that the raw material part reaches the maximum temperature in the high thermal conductivity raw material layer and a SiC single crystal ingot is grown.