A New Look at Silicon Carbide

At a Glance

Metadata	Details
Publication Date	2023-05-01
Journal	IMAPSource Proceedings
Authors	Frank Muscolino
Analysis	Full AI Review Included

6CCVD Technical Documentation: Diamond Solutions for Advanced Silicon Carbide (SiC) Power Electronics

This document analyzes the challenges presented in the SiC manufacturing process, particularly concerning thermal management and material processing, and outlines how 6CCVD’s MPCVD diamond materials (SCD, PCD, BDD) provide critical solutions for high-power, high-frequency applications.

Executive Summary

The research highlights the critical role of Silicon Carbide (SiC) in high-power electrification (EVs, solar, wind) but identifies significant manufacturing and packaging bottlenecks due to its extreme physical properties. 6CCVD’s MPCVD diamond directly addresses these limitations:

Extreme Hardness Mitigation: SiC’s Mohs hardness (9.5) necessitates diamond tooling for efficient sawing, dicing, and polishing. 6CCVD supplies high-purity Polycrystalline Diamond (PCD) plates for durable, high-throughput processing tools.
Superior Thermal Management: SiC devices operate at extreme temperatures (>200 °C) and high power (>1000W). Single Crystal Diamond (SCD) offers thermal conductivity significantly exceeding SiC (up to 5x better than copper), essential for submounts and heat spreaders.
Custom Integration: 6CCVD provides custom metalization (e.g., Ti/Pt/Au) on SCD/PCD substrates, enabling robust, high-temperature die attach methods like silver sintering (melting point 960 °C).
Scalability and Dimensions: We offer large-area PCD wafers (up to 125mm) and custom SCD plates, matching the industry trend toward 4-inch and 6-inch SiC wafers for scalable manufacturing.
Enhanced Reliability: Utilizing diamond substrates minimizes thermal expansion mismatch and improves heat dissipation, directly contributing to lower FIT rates and extended device life, critical for automotive and renewable energy applications.

Technical Specifications

The following data points extracted from the research define the extreme operating environment and material requirements for SiC power devices, highlighting the need for diamond solutions.

Parameter	Value	Unit	Context
SiC Mohs Hardness	9.5	N/A	Approaches diamond (10); requires diamond tooling for processing.
SiC Thermal Conduction (4H-SiC)	3.7	W/cm·K	High relative to Si (1.5 W/cm·K), but insufficient for extreme power density.
SiC Band Gap Energy (4H-SiC)	3.26	eV	Enables high-voltage, high-temperature operation.
Typical Operating Temperature	200+	°C	Required stability for die attach and molding compounds.
Typical Operating Voltage	>1000	W	High power requirement for EV/renewable energy applications.
Silver Sinter Die Attach Thermal Conductivity	250	W/m·K	High-performance die attach method used for SiC.
Silver Sinter Die Attach Melting Point	960	°C	Requires high-temperature stable substrate metalization.
SiC Market Projection (2026)	1.5	Billion	USD

Key Methodologies

The paper details the SiC manufacturing flow, emphasizing steps where the material’s hardness and thermal requirements create bottlenecks.

Boule Growth: SiC is grown using a Low-Pressure Chemical Vapor Deposition (LPCVD) process, yielding 4-inch and 6-inch single crystal boules.
Wafer Sawing: The boule is sliced into wafers using one or multiple diamond coated wires. This process is slow (typically 2 hours for 15 wafers) due to SiC’s extreme hardness and brittleness.
Wafer Polishing: Raw wafers are polished using standard Chemical Mechanical Polishing (CMP) techniques, but speeds must be lowered to prevent chipping, resulting in lower throughput (UPH).
Die Singulation: Individual devices are separated, traditionally via slow-speed diamond sawing or increasingly via advanced laser scribing to minimize chipping and defects.
Die Attach: High-power devices require high thermal conductivity attachment, typically using silver sintering (pressure or pressure-less) at approximately 240 °C and 10 MPa.
Wire Bond: Requires thick copper wire, copper ribbon, or copper clip bonding to handle large current and heat dissipation requirements.
Epoxy Over Molding: Requires specialized compounds with high temperature stability and higher breakdown voltages than standard Si epoxy.

6CCVD Solutions & Capabilities

6CCVD provides the advanced MPCVD diamond materials necessary to overcome the processing and thermal limitations inherent in high-performance SiC power electronics manufacturing.

Applicable Materials for SiC Integration

Application Area	6CCVD Material Recommendation	Key Benefit
Thermal Management / Submounts	Optical Grade SCD (Single Crystal Diamond)	Thermal conductivity > 20 W/cm·K (up to 5x better than SiC’s 3.7 W/cm·K). Essential for mitigating heat in 200+ °C operating environments.
High-Power Heat Spreaders	High-Purity PCD (Polycrystalline Diamond)	Cost-effective, large-area solution (up to 125mm diameter) for high-volume thermal management in power modules.
High-Temperature Electrodes / Sensors	Heavy Boron Doped Diamond (BDD)	Stable electrical properties at high temperatures (>200 °C) and high voltages, ideal for integrated sensing or high-performance contacts.
Processing Tooling	PCD Plates (Thick)	Used for manufacturing durable diamond wire drawing dies, CMP pads, and dicing blades required to process SiC (Mohs 9.5).

Customization Potential for SiC Device Integration

The successful integration of SiC devices requires specialized material handling and preparation, which 6CCVD is uniquely positioned to provide:

Custom Dimensions: The paper notes the transition to 4-inch and 6-inch SiC wafers. 6CCVD offers PCD plates up to 125mm (5 inches) in diameter, perfectly sized for use as thermal spreaders or processing substrates compatible with standard SiC wafer sizes.
Precision Thickness Control: We provide SCD and PCD layers from 0.1 µm up to 500 µm, allowing engineers to optimize thermal resistance and mechanical stability for specific power module designs. Substrates up to 10mm are available for robust tooling.
High-Temperature Metalization: The use of silver sintering (960 °C melting point) for die attach demands stable metalization. 6CCVD offers in-house metalization services including Ti/Pt/Au, W, and Cu, ensuring robust, high-adhesion contacts capable of withstanding extreme processing and operating temperatures.
Ultra-Low Roughness Polishing: To ensure optimal thermal contact and bonding for die attach, 6CCVD guarantees Ra < 1 nm for SCD and Ra < 5 nm for inch-size PCD, minimizing interfacial thermal resistance.

Engineering Support

6CCVD’s in-house PhD team specializes in the material science of wide bandgap semiconductors and thermal management. We can assist customers with material selection, thermal modeling, and interface engineering for similar High Voltage, High Power SiC Module projects, ensuring optimal performance and reliability.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

Silicon Carbide, SiC is one of the most widely used materials that plays a critical role in industries such as: aerospace, electronics, industrial furnaces and wear-resistant mechanical parts among others. Although SiC is widely used in electronics and other high technology applications, the metallurgical, abrasive, and refractory industries are dominate by volume. It is only in the last five or six years that SiC has gained a new and important role in the semiconductor industry. SiC has become a key material in the drive towards electrification. It’s unique physical properties, wide band gap, especially, high temperature performance and “ease of manufacturability makes it a key material going forward. The physical properties that make SiC so unique also represent some serious problems to large scale manufacturing of SiC diodes, transistors and modules. SiC is a very tough material, it has a Mohs hardness rating of 9.5 approaching that of diamond. Just as the semiconductor industry needed high quality defect free silicon wafers to move forward, so did the SiC industry. High quality defect free wafers have just come into the market. They are 4 and six wafers that will allow SiC. These boules can be “sliced” in wafers and run on a standard CMOS fabrication process. Next comes the dicing of the wafers into devices. A diamond saw has to be run at a very slow rate to a material almost as hard as the diamond itself. Die attach brings an interesting problem the devices are generally rate at 200+ deg C and voltages >1000W. Standard epoxy and even Au/Si eutectic die attach has issues has issues at these extreme operating conditions. Lastly, the epoxy molding compound has to be capable of withstanding the harsh conditions and not breakdown. These are all challenges that are being met today. This is a continuing story of how the semiconductor industry adapts to ever changing requirements

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Original Source

DOI: https://doi.org/10.4071/001c.74738