The road to the future is not always a smooth, trouble-free drive. Along the way, there may be unforeseen detours, potholes and accidents, each one capable of setting progress back. But for those behind the wheel, those obstacles are just a part of the journey.

Such is the case for the automotive industry as it continues to steer away from gas-powered vehicles and turn toward hybrid and electric vehicles. To accomplish this, manufacturers of power devices are opting to use wide-bandwidth compound semiconductors like SiC and GaN. The reason: compound semiconductors accommodate higher voltages, faster switching speeds and lower losses than traditional silicon-based power devices.

For the purpose of our three-part series, we have been focusing on SiC power devices, the challenges presented by trench-based architectures that reduce on-resistance and increase carrier mobility, and the need to accurately measure epi layer growth and the depth of implant layers. Before we move onto the details of this blog, let’s take a quick look back at the previous two blogs.

You don’t have to be a dedicated follower of the transportation industry to know it is in the early stages of a significant transition, away from the rumbling internal combustion engine to the quiet days of electric vehicles. The signs of this transition are right there on the streets in the form of electric-powered buses, bikes and cars. The road to our electric future is before us, but we won’t be getting there without compound semiconductors like SiC.

Manufacturers in the automobile and clean energy sectors want more efficient power devices that can accommodate higher voltages, possess faster switching speeds and offer lower losses than traditional silicon-based power devices, something SiC power devices with trench structures can deliver.

But while trench-based architectures offer reduced on-resistance and increase carrier mobility, they bring along increased complexity. For manufacturers of SiC power devices, the ability to accurately measure epi layer growth and the depth of implant layers in these trenches is of considerable concern, especially when faced with ever-increasing fabrication complexity.

In the previous blog in this series, we explored how using an FTIR-based system allows for the direct modeling of carrier concentrations and film thickness, thus enabling SiC power device makers to better measure epi layer growth, implant layers and composition. In this installment, we explore how manufacturers of SiC power devices with trench-based structures measure trench depth and bottom and top critical dimension (CD) by using an optical critical dimension (OCD) metrology system designed for specialty devices.

The figures alone are impressive: SiC power devices are experiencing an annual average growth rate approaching 34% through 2027, according to the Yole Group. However, the potential for this amongst other compound semiconductor-based power devices such as gallium nitride (GaN) to change the world around us is even more impressive.

Thanks to the role that SiC-based devices play in the increased electrification of automobiles and the sustainable energy movement, the effort to make this world a cleaner, greener place is no longer a wished-for science fiction fantasy. It may one day be our reality. Perhaps even soon.

Manufacturers in the automobile and clean energy sectors want power devices that are more efficient and can accommodate higher voltages, faster switching speeds and lower losses than traditional silicon-based power devices. To accomplish this, they are turning to higher efficiency silicon carbide (SiC)-based devices.

When it comes to SiC power devices, most manufacturers have adopted a trench-based architecture. This reduces on-resistance and increases carrier mobility. However, these improvements come at the expense of rising fabrication complexity.

To address this issue, high-volume manufacturers of SiC power devices are, at several key steps, adopting inline process control methods, including optical metrology techniques like Fourier transform infrared (FTIR). With a system supporting FTIR optical metrology at their disposal, manufacturers can more accurately measure epi layer growth and the depth and accuracy of implanted dopants across the wafer, key challenges posed by the increased fabrication complexity of SiC power devices. In this blog, we’ll discuss how FTIR technology can help manufacturers successfully address these challenges.

Wind power. Rail. Solar energy. And, perhaps most significantly, electric and hybrid vehicles. Together, these four forces are among the major demand drivers for power devices.

While silicon (Si) still plays a role in power devices, wide-bandgap compound semiconductors like silicon carbide (SiC) and gallium nitride (GaN) are particularly well-suited for power devices thanks to their higher electron mobility, higher critical electric field and higher thermal conductivity. However, as new structures and larger wafer sizes become the norm for power devices, they bring with them distinct manufacturing challenges.

Today, the industry is transitioning from 150mm to 200mm wafers for SiC- and GaN-based devices and 200mm to 300mm wafers for Si-based devices. The reason: larger wafer sizes may help reduce the cost of fabrication. As the wafer size transition occurs, it is important to have a metrology tool that can measure a larger number of data points across the wafer without impacting the overall fab throughput. A loss of throughput adds to cost-of-ownership and may erase savings earned from transitioning to larger wafers.