The Building Blocks of Silicon Carbide, a Rising Star

In today’s fast-paced, high-energy, and highly competitive world of technology, it takes a clear vision and steady execution to leave your competitors in the dust. Survival of the fittest in a technological revolution is about finding the next big thing and flawlessly bringing it to market.

For the world of power electronics the next big thing is silicon carbide (SiC). Silicon-based chips are currently used to manage power in everything from portable electronics to industrial-scale equipment. Silicon-based chips are the workhorse of the industry. The technology is familiar and the chips are readily available. A decade of work and a keen eye for the future have enabled scientists at GE Global Research to introduce the first industrially ready SiC devices to the world. These devices operate at higher frequencies and temperatures and convert electric power at higher efficiencies. Additionally, SiC-based devices manage the same level of power at half the size, enabling dramatic increases in power density and reliability.

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GE recognized the great potential of SiC technology more than 50 years ago, but early progress was stymied by the material’s immaturity.  As the material improved over decades, the race was on to develop industrially ready SiC devices.

This was not as simple as it might sound. Research groups around the world quickly discovered that it was difficult to make stable and reliable SiC MOSFETs (Metal Oxide Semiconductor Field Effect Transistors).

“When we started this work in 2005, the prevailing view was that industrially ready SiC MOSFETs would never be feasible,” said Ljubisa Stevanovic, GE Global Research’s advanced technology leader for silicon carbide. “We knew, however, that they would be the ideal device for a majority of applications, so we focused all our efforts on solving the challenge of making industrially ready SiC MOSFETs.”

The GE scientists working on SiC took on that challenge with gusto. It takes more than 200 steps and two months to fabricate a SiC power device, so cracking the MOSFET code was far from straightforward. They had to break the process down step by step and ingredient by ingredient to understand how each impacted the other. What made the process more challenging was the vast array of requirements – adjusting the process to meet one requirement would make it more difficult to meet another. At one point the recipe for the SiC MOSFET got lost and could not be re-created.

The team had to start fresh with a much more rigorous approach. Each step and material was validated and introduced in a methodical fashion leading to a stable, reliable, and repeatable process that delivers a device that meets the many unique industrial requirements.  In 2009, the team demonstrated the first stable, industrially ready SiC MOSFET. GE is the only team in the world to have achieved this, though there are several companies that are pushing forward with devices that meet some – but not all – of these requirements.

The GE team’s meticulous approach, combined with the deep application expertise available in house, enabled success.   With co-workers who are experts in all of the potential application areas for SiC, the team knew just how these devices were going to be utilized and the stresses that they would have to endure.  This breadth of knowledge is something other device companies just don’t have access to, they are not plugged into the systems and applications knowledge in the way GE Global Research’s team is.  These synergies and cross-pollination of knowledge are referred to as the “GE Store.”

“It took the early mistakes and the re-emphasis on a rigorous and methodical approach, combined with the deep breadth of application knowledge available at GE Global Research, for us to develop the only industrially ready SiC MOSFETs. Without all of those factors, a robust SiC MOSFET product would likely still be elusive,” Ljubisa said.

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Another pivotal moment in GE’s SiC story was the decision to forego licensing and hold the technology in-house. Scale is an important advantage in the semiconductor industry, which is ruled by the mantra “go big or go home.” GE’s entry into SiC was originally motivated by high-value, low-volume Aviation applications, but as the technology matured and the decision was made to keep it in-house, GE’s focus has shifted to expanding opportunities on the application side and scaling up manufacturing. Today’s SiC efforts are two-pronged: identifying applications for SiC in existing GE products while also selling SiC devices to other companies, even competitors.

“While our research and development efforts commenced with GE’s Aviation business,  the prospect of incorporating SiC into GE’s vast portfolio of products convinced us that the effort should remain internal,” said Danielle Merfeld, GE Global Research’s global technology director for electrical technologies and systems. “By vertically integrating SiC technology, we can cut production costs and engage in a healthy internal discussion that promotes product optimization.” (For more about how SiC-based devices will be used in GE’s products, click here.)

GE has simultaneously launched a SiC commercial enterprise, similar to a start-up and housed within GE Global Research, that will sell SiC devices to users in the industrial and automotive fields – even competitors of some GE businesses.  This effort is crucial for building volume and reducing overall costs for customers, both within GE and outside the company.

The approach is completely unique and is a product of a groundbreaking partnership with New York State.

In 2013, GE partnered with New York State and State University of New York’s Polytechnic Institute to answer a call for proposals by the U.S. Department of Energy. The DOE wanted one of its new manufacturing institutes to focus on SiC. Although the New York SiC bid was not selected, the experience still proved to be fruitful.

“We built a strong partnership with SUNY Polytechnic and it was clear to both parties that continuing our relationship would allow us to meet our shared goals faster,” said Ljubisa.

“Staying power in the semiconductor industry requires agility so we quickly shifted our focus to building an infrastructure that would help us succeed,” said Danielle. “SiC is the next big thing in power electronics and we are excited about leading the way with a strong team of engineers and scientists.”

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The first public announcement about GE’s SiC development came in July 2014 when GE and the SUNY Polytechnic created the New York Power Electronics Manufacturing Consortium (NY-PEMC). This partnership will boost production by creating a manufacturing line at SUNY Polytechnic in Albany and drive down manufacturing costs by scaling up from 4” wafers to 6” wafers.

“A larger wafer will accommodate two to three times more devices, so we’re talking a sizeable increase in output over the two month, more than 200-step manufacturing process,” said Danielle. “The most recent announcement concerns the modules in which these devices are placed and the consortium’s effort to increase packaging efficiency and speed.”

In August 2015, GE and SUNY Polytechnic announced that the modules and power blocks will be created at a new facility in Utica. These higher level assemblies are specially designed to harness the full power of SiC and will be integral to the success of SiC as a product. The power block assemblies will reduce the time to market by optimizing assembly of multiple modules, controls, and cooling. GE’s partnership with SUNY Polytechnic in Albany and Utica will allow the SiC business to be scaled up to deliver the volume and cost profile necessary to bring the technology mainstream.

As GE’s partnership with New York State matures, the next step will involve simplifying integration of SiC technology into both GE and non-GE products. The goal will be to reduce the time to market by streamlining the power block assembly, which includes multiple modules, controls, and cooling.

“Our plan is to lead by example and to influence the market by being the first full-scale adopter of this technology,” said Danielle. “It’s a big risk for GE and we’re betting on  more than 50 years of our own research and development to revolutionize an industry.”