Polymer Filter for SiC Crystal Growth Impurity Control

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Solution Overview

Problem

The growth of high-quality single crystals of silicon carbide (SiC) is hindered by carbon impurities and contaminants introduced during the seeded growth sublimation process, leading to defects in the crystal.

Innovation Solution

An apparatus with a filter part made of polymer with a fibrous structure is used to selectively filter out carbon impurities and control the sublimation rate, ensuring a flat raw material surface and uniform silicon carbide gas supply, thereby preventing impurity introduction and enhancing crystal growth quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a seeded growth sublimation scheme is used to grow SiC single crystal, then the single crystal growth technology becomes stable and can be used extensively, but carbon impurities and contaminants from the raw material are introduced into the single crystal causing defects

Engineering Contradiction:

Improvesingle crystal growth stabilityVSAvoidcarbon impurity introduction

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A filter part made of polymer material with specific pore size is introduced as an intermediary component between the raw material and the seed crystal. This filter selectively allows SiC vapor to pass through while blocking carbon impurities and contaminants, thus mediating the sublimation process to prevent harmful substance introduction while maintaining crystal growth stability

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The filter part utilizes porous polymer material with controlled pore dimensions that enable selective permeation. The porous structure allows SiC molecules to diffuse through while physically blocking larger carbon impurity particles, solving the contradiction between maintaining stable growth conditions and preventing contamination

Inventive Principle:

Principle #31Porous materials

2Productivity

If the sublimation rate is increased to improve crystal growth rate, then productivity increases, but carbon impurities are more likely to be introduced into the crystal causing defects

Engineering Contradiction:

Improvecrystal growth rateVSAvoidcarbon impurity introduction

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The filter part serves as a mediator that decouples the relationship between sublimation rate and impurity introduction. By placing the filter between the raw material and seed, high sublimation rates can be maintained while the filter continuously blocks carbon impurities from entering the crystal, allowing productivity improvement without compromising quality

Inventive Principle:

Principle #24Intermediary (Mediator)

3Manufacturing precision

If a filter part is introduced to block carbon impurities, then crystal quality improves, but the device complexity increases

Engineering Contradiction:

Improvesingle crystal qualityVSAvoidapparatus structure

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The filter part is made of relatively simple polymer material that can be easily replaced. Rather than designing a complex permanent filtration system, the invention uses a simple, inexpensive filter component that performs its function effectively and can be replaced when needed, thus improving crystal quality without significantly increasing overall device complexity

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The filter is implemented as a thin polymer film or membrane that can be easily integrated into the existing apparatus structure. This thin-film approach minimizes the added complexity while providing effective filtration, as the flexible nature of the polymer allows it to conform to the crucible geometry

Inventive Principle:

Principle #30Flexible shells and thin films

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

The filter part effectively blocks impurities, improves durability, and increases the growing rate of high-quality single crystals by uniformly supplying silicon carbide gas, reducing defects and maintaining a flat surface during the growth process.

Implementation Method 1

the filter part may adsorb the carbon impurities. That is, the carbon impurities generated from the raw material may be prevented from participating in the process of growing the single crystal

Methodology Applied

Scientific EffectAdsorption: Adsorption

Implementation Method 2

the filter part may have a fibrous structure. That is, since the filter part has a continuous fibrous structure, necking (chemical bonding) is formed between fibers

Methodology Applied

Scientific EffectPermeation: Permeation

Implementation Method 3

a seeded growth sublimation scheme has been suggested. In this case, after putting SiC powder serving as a raw material in a crucible

Methodology Applied

Scientific EffectSublimation: Sublimation

Data Source

PatentUS9540744B2Apparatus for fabricating silicon carbide single crystal ingot and method for fabricating ingot

Publication Date: 2017.01.10 LG INNOTEK CO LTD

AI summary

An apparatus for fabricating an ingot according to the embodiment comprises a crucible for receiving a raw material; and a filter part for selectively filtering a specific component in the crucible, wherein the filter part comprises a polymer.