Composite SiC Substrate Heat Dissipation Fabrication

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current heat dissipation substrates for high-power frequency components, such as those made of single-crystal SiC, are costly and have high thermal impedance, which can lead to component damage due to inadequate heat dissipation, while polycrystalline substrates offer a lower-cost alternative but still require improved thermal management.

Innovation Solution

A composite structure is fabricated using a polycrystalline support substrate with a thin crystalline top layer and an oxide layer at the bonding interface, where the structure undergoes heat treatment in a non-oxidizing atmosphere to enhance heat dissipation properties by reducing the oxide layer thickness, thereby improving thermal conductivity without increasing costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If single-crystal bulk SiC substrates are used for heat dissipation, then heat dissipation performance is improved, but manufacturing cost increases significantly

Engineering Contradiction:

Improveheat dissipation performanceVSAvoidmanufacturing cost

Core Design Contradiction:

TemperatureVSEase of manufacture

Solution Approach 1:

The patent employs a composite structure consisting of a polycrystalline SiC substrate layer, a bonding interface layer, and a single-crystal SiC top layer. This composite architecture allows the bulk substrate to be made of cost-effective polycrystalline material while maintaining a single-crystal surface for device fabrication, thereby achieving good heat dissipation performance without the high cost of entirely single-crystal SiC substrates

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The invention applies local quality by requiring single-crystal structure only at the top layer where device fabrication occurs, while the bulk substrate can be polycrystalline. This localized approach to crystal quality optimizes cost-effectiveness while preserving the necessary thermal and electrical properties at the device interface

Inventive Principle:

Principle #3Local quality

2Ease of manufacture

If polycrystalline substrates are used to reduce cost, then manufacturing cost decreases, but thermal conductivity and heat dissipation capability are insufficient

Engineering Contradiction:

Improvemanufacturing costVSAvoidthermal conductivity

Core Design Contradiction:

Ease of manufactureVSTemperature

Solution Approach 1:

The composite structure combines polycrystalline SiC substrate with a single-crystal SiC top layer, leveraging the cost advantage of polycrystalline material for the bulk while utilizing the superior thermal and electrical properties of single-crystal material at the functional interface, thus resolving the contradiction between cost and thermal performance

Inventive Principle:

Principle #40Composite materials

3Strength

If oxide layer is present at bonding interface, then bonding strength is improved, but thermal impedance increases and heat dissipation is reduced

Engineering Contradiction:

Improvebonding strengthVSAvoidthermal impedance

Core Design Contradiction:

StrengthVSTemperature

Solution Approach 1:

The patent optimizes the oxide layer parameters by controlling its thickness to remain below 5 nm through precise oxidation time and temperature control. This parameter optimization maintains sufficient bonding strength while minimizing the thermal impedance introduced by the oxide layer, thereby resolving the contradiction between bonding strength and heat dissipation

Inventive Principle:

Principle #35Parameter changes

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 method results in a cost-effective composite structure with enhanced heat dissipation capabilities, suitable for high-frequency applications, by reducing the oxide layer thickness through controlled heat treatment, thereby improving thermal conductivity and maintaining structural integrity.

Implementation Method 1

the structure undergoes heat treatment in a non-oxidizing atmosphere to enhance heat dissipation properties by reducing the oxide layer thickness

Methodology Applied

Scientific EffectHeat treatment: Heat Treatment

Data Source

PatentUS7452785B2Method of fabrication of highly heat dissipative substrates

Publication Date: 2008.11.18 SOITEC SA

AI summary

The invention relates to a method for fabricating a composite structure having heat dissipation properties greater than a bulk single crystal silicon structure having the same dimensions. The structure includes a support substrate, a top layer and an oxide layer between the support substrate and the top layer. The method includes providing a top layer made of a crystalline material, providing a support substrate of a polycrystalline material having heat dissipation properties greater than that of a bulk single crystal silicon substrate of the same dimensions; providing an oxide layer on at least one of the top layer or the support substrate; bonding the top layer and support substrate together to obtain a composite structure having the top layer, the support substrate and the oxide layer located at a bonding interface between the top layer and support substrate, and heat treating the composite structure in a non-oxidizing atmosphere at a predetermined temperature and for a predetermined duration to dissolve at least part of the oxide layer and increase the heat dissipation properties of the composite structure compared to the composite structure prior to the heat treating.