Silicon Carbide Crystal Growth Using Axial-Radial Gradient Ratio Control

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Solution Overview

Problem

Existing methods for growing silicon carbide crystals are inefficient, taking several years to expand the diameter from 6 inches to 8 inches and fail to produce crystals with a high monocrystalline proportion in a short time.

Innovation Solution

A crystal growing method that involves multiple crystal growth processes, adjusting the ratio difference between axial and radial temperature gradients (ΔTz/ΔTx) within a specific range (0.5 to 3) and controlling nitrogen doping concentration (2*10^18 to 3*10^18 atoms/cm^3) to achieve a monocrystalline proportion of 100% in a reduced timeframe.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If traditional crystal growth methods are used to expand silicon carbide crystal diameter from 6 inches to 8 inches, then crystal size is increased, but the process takes several years and productivity is extremely low

Engineering Contradiction:

Improvecrystal diameterVSAvoidcrystal growth speed

Core Design Contradiction:

Volume of moving objectVSProductivity

Solution Approach 1:

The patent applies parameter changes by precisely controlling the ratio difference (ΔTz/ΔTx) of axial and radial temperature gradients within a specific range (0.5-3.0), and adjusting nitrogen doping concentration (2×10^18 to 3×10^18 atoms/cm³) during crystal growth. These parameter optimizations enable significantly accelerated crystal growth while maintaining high monocrystalline proportion, resolving the contradiction between crystal size expansion and productivity.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If traditional crystal growth methods are used, then crystal size increases gradually, but the monocrystalline proportion cannot be effectively improved in a short time

Engineering Contradiction:

Improvemonocrystalline proportionVSAvoidcrystal growth time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent achieves rapid improvement of monocrystalline proportion by optimizing temperature gradient ratio (ΔTz/ΔTx) and nitrogen doping concentration parameters. By maintaining the temperature gradient ratio within 0.5-3.0 and controlling nitrogen concentration at 2×10^18 to 3×10^18 atoms/cm³, the method accelerates monocrystallization process from years to months, effectively resolving the time-m quality contradiction.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements a feedback mechanism by repeatedly performing crystal growth processes (N times, where N>3) and evaluating the monocrystalline proportion after each cycle. Based on the evaluation results, the process parameters are adjusted and optimized in subsequent cycles, enabling progressive improvement of monocrystalline proportion until 100% is achieved, thereby reducing total process time.

Inventive Principle:

Principle #23Feedback

3Manufacturing precision

If multiple crystal growth processes are performed to increase monocrystalline proportion, then crystal quality improves, but the number of processing steps increases and device complexity rises

Engineering Contradiction:

Improvemonocrystalline proportionVSAvoidnumber of processing steps

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent uses feedback control by evaluating monocrystalline proportion after each crystal growth process and using the evaluated crystal as seed for the next process. This closed-loop approach systematically improves crystal quality through N repeated processes (where N>3), with each cycle building upon the previous results to achieve 100% monocrystalline proportion while managing process complexity through structured iteration.

Inventive Principle:

Principle #23Feedback

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

Significantly shortens the time required to form large-sized silicon carbide crystals with high monocrystalline proportion, achieving uniform resistivity, reduced defects, and improved geometry.

Implementation Method 1

adjusting a ratio difference (ΔTz/ΔTx) of an axial temperature gradient (ΔTz) and a radial temperature gradient (ΔTx) of the crystals

Methodology Applied

Scientific EffectTemperature gradient: Temperature Gradient

Implementation Method 2

controlling a doping amount of the nitrogen concentration in a range of 2×10^18 atom/cm³ to 3×10^18 atom/cm³

Methodology Applied

Scientific EffectDoping: Dopants

Data Source

PatentUS12509794B2Method of performing crystal growth processes on a first crystal seed by adjusting a ratio difference of an axial temperature gradient and a radial temperature gradient

Publication Date: 2025.12.30 GLOBALWAFERS CO LTD

AI summary

A crystal growing method for crystals include the following steps. A first crystal seed is provided, the first crystal seed has a first monocrystalline proportion and a first size. N times of crystal growth processes are performed on the first crystal seed, wherein each of the crystal growth process will increase the monocrystalline proportion, and the N times of crystal growth processes are performed until a second crystal having a monocrystalline proportion of 100% is reached, and wherein the N times includes more than 3 times of crystal growth processes. Each crystal growth process includes adjusting a ratio difference (ΔTz/ΔTx) between an axial temperature gradient (ΔTz) and a radial temperature gradient (ΔTx) of the crystal, so as to control the ratio difference within a range of 0.5 to 3 for forming the second crystal.