Coherent’s silicon carbide business has received an investment boost from DENSO and Mitsubishi Electric, enabling Pittsburgh-based Coherent to focus on substrate and epi-wafer level manufacturing for wide bandgap power device production.
Chromium defects in SiC can form an ordered three-asymmetric two orbital triplet ground state and an excited one-singlet doublet state with long T1 times, providing high-fidelity spin initialization.
Substrates
Silicon carbide (SiC) boasts an extremely wide bandgap that provides higher breakdown electric field and superior thermal conductivity for compact, rugged devices. Manufacturers can produce multiple devices per wafer to minimize costs and power usage. SiC-based power semiconductors play an integral part in power conversion for EVs/HEVs as well as energy infrastructure applications and high-power EV chargers.
DENSO is an established supplier to both automotive and electrical equipment manufacturers, long touting the benefits of SiC substrates as a crucial element for creating zero-carbon societies through widespread adoption of battery electric vehicles – an effort supported by Coherent’s steady supply of SiC substrates and epi-wafers.
Coherent’s goal of providing customers with superior SiC solutions has resulted in its launch of a 200 mm SiC epi-wafer manufacturing business. Shipments have already begun of 350 and 500 micron thickness substrates and epi-wafers manufactured using its fully vertically integrated SiC manufacturing capability, featuring advanced thickness and doping uniformity standards that set industry standards for superior SiC power semiconductors.
Epi-Wafers
Epitaxial wafers crafted of coherent silicon carbide are manufactured through photolithography, ion implantation and thermal diffusion techniques. Handle wafer and active wafer are joined with an oxide layer for use in semiconductor device fabrication while the epitaxial wafer itself is cut into various shapes and sizes using chemical etching, grinding polishing and slicing processes.
Coherent epitaxial wafers offer fast time-to-market, reduced costs, and superior device performance compared to their competition. Used to fabricate various semiconductor devices like RF power amplifiers, MOSFETs, IGBTs and GaN-on-SiC HEMTs fabricated on them by fabricating.
Epitaxial wafers enable chipmakers to increase usable area by an estimated 1.8x, helping improve productivity and cut operational costs while expanding into larger wafers in line with industry trends that focus on greater yields and cost efficiencies. Demand from critical sectors such as electric vehicles, energy infrastructure, and high-power EV chargers necessitate this expansion into larger wafers.
Coherent’s decision to increase production of 200 mm SiC epi-wafers comes at a crucial time. As global power electronics based on SiC are projected to experience rapid expansion due to climate change mitigation initiatives and rising adoption of electric vehicles, reliable supply of SiC substrates and epi-wafers will become ever more essential for sustained market expansion.
Devices
Power electronics crafted using SiC offer unparalleled performance over devices made with regular silicon (Si). Their higher breakdown electric field strength, wider bandgap and superior thermal conductivity enable compact, high-efficiency devices with reduced power loss and greater range in electric vehicles (EV).
As demand has increased for SiC products and devices, many makers of the material and devices have announced major expansion plans. Wolfspeed recently claimed it had built the world’s largest SiC factory; Infineon recently unveiled plans for a new plant which will produce SiC chips specifically tailored for automotive use.
Coherent has recently made headlines for securing a $1 billion investment from Denso and Mitsubishi Electric to aid production of SiC substrates and epi-wafers. As part of this transaction, each Japanese firm will receive a non-controlling 12.5% stake in Coherent as well as long-term supplies of 6-inch and 8-inch SiC substrates and epi-wafers from Coherent.
Coherent has started shipping substrate and epi-wafers up to 200 mm. Lines for processing this larger diameter have already come online and tools have begun qualification processes, making these higher performance wafers suitable for making SiC MOSFETs and IGBTs for high temperature power electronics like those found in electric vehicle (EV) chargers as well as GaN-on-SiC power amplifiers. Furthermore, these semi-insulating substrates help manufacturers accelerate time to market while simultaneously cutting costs by simplifying device design as well as faster integration into end products.
Applications
Silicon carbide semiconductors can withstand higher temperatures than silicon (SI) chips, while also offering significantly increased power efficiency. That means they can transmit and convert energy more effectively without losing it as heat, thus reducing cooling needs for power electronics while creating smaller devices that save space, weight and cost.
This increase in efficiency is made possible by 200 mm wafers. Their larger size provides device manufacturers with a 1.8x increase in usable area, enabling more SiC power devices to be produced more rapidly and efficiently – meeting increasing demands for high-quality SiC power electronics from critical sectors such as electric vehicles, energy infrastructure and high-power EV chargers.
DENSO and Mitsubishi Electric have invested a combined total of $1 billion into Coherent’s SiC semiconductor business, now known as Silicon Carbide LLC. Each corporation invested $500 million for an 12.5 percent non-controlling interest. Furthermore, arm’s length long-term supply agreements were set up supporting 150mm substrate and 200mm epitaxial wafer demand.
Sohail Khan, Executive Vice President of Wide-Bandgap Electronics at Coherent, believes investing in its own subsidiary will allow his company to maximize learning from working closely with customers from device or module design through to deployment and service delivery. Khan strongly believes this will guarantee customers receive top quality products and services.
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