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Unlocking the Power Potential: How Silicon Carbide is Revolutionizing Semi Fab/Process Power Supplies
Semiconductor device fabrication processes involve a series of intricate steps that require reliable power supplies. The use of Silicon Carbide (SiC) power supplies, with their power density, reliability, and design flexibility, is gaining recognition among engineers for previously untapped applications. To maximize power density and flexibility, Wolfspeed and Astrodyne TDI (ATDI) have come together to harness the benefits of SiC technology in meeting the power supply requirements of modern semiconductor fab/process equipment. Our collaboration has resulted in higher power density achieved through the implementation of SiC devices, notably showcased in ATDI's innovative Kodiak power supply platform, which boasts a power density of 40 W/in3. Leveraging Wolfspeed's extensive expertise in developing robust SiC-based solutions, ATDI can deliver superior power converters, enabling customers to enhance their process control capabilities.
Power Supplies are an End-to-End Requirement
Power supplies are essential to the vast array of equipment utilized in semiconductor fabrication processes. One particular area where their significance is highlighted is in testing. While transforming silicon into delicate wafers containing intricate circuitry, these wafers are eventually cut into individual chips known as dies. Before the final singulation, each integrated circuit undergoes rigorous testing, even at high temperatures, to ensure optimal performance within specified parameters. Power plays a critical role in this process, with power levels needing to be remarkably high while maintaining deficient noise levels.
Power supplies also play a crucial role in the implantation stage, which involves the introduction of specific ions into materials to refine their properties. Commonly referred to as "semiconductor doping," this process incorporates ions, also known as dopants, such as boron, phosphorus, or arsenic, to introduce impurities that modulate the electronic properties of the device. Accomplishing a successful implantation process necessitates using high-energy electron beams generated by equipment with reliable power supplies to generate, steer, and focus the beam using electromagnets.
Etching and deposition equipment in semiconductor fabrication requires a reliable and constant power source. Whether wet or dry etching, both methods transform a thin film of material into essential circuit interconnects and components. With the help of photolithography, the etching process eliminates any unnecessary material, leaving behind only the intricate circuit patterns crucial for the device's functionality. Consistent electrical power is also vital for the deposition process, which involves using techniques like evaporation or sputtering to create different metal layers that form electrical connections between cells. It is crucial to maintain the uniformity of the deposited material to ensure even layers are formed.
Moreover, the power converters used in these tools play a significant role in the entire semiconductor fabrication process. They are not just responsible for providing a consistent voltage source; they must also dynamically control the delivered power or current with high precision. In the past, AC––line–frequency–based converters were commonly utilized due to their ability to adapt to varying AC voltages in fabs worldwide, ranging from 100 to 480 VAC. However, introducing SiC technology has revolutionized these applications by enabling high-frequency switch-mode (HFSM) converters. These converters offer remarkable advantages in terms of performance and power density.
All these semiconductor fabrication processes greatly benefit from high-density power supplies as close to the tools as possible. This results in tighter processes with enhanced precision, reduced complexity, and shorter process times, ultimately leading to a faster time to market. HFSM power supplies, leveraging the power of SiC technology, provide greater flexibility for those involved in building power supplies for semiconductor fabrication equipment.
Finding a Balance Between Power Density and Flexibility
ATDI has used second-generation SiC devices for its power supplies for nearly a decade. It has migrated to third-generation devices in the Kodiak platform to provide a standard building block that can be integrated into many custom solutions. By adapting the latest SiC technology, ATDI has improved power density to solve customers’ high-complexity problems. The industry-leading 40-W/in3 power density achieved in the Kodiak product is enabled by the low losses in the SiC MOSFETs and associated body diodes, which allowed for highly efficient and flexible power topologies to be selected.
Along with high density, Kodiak is compatible with global AC power sources and provides high-precision control of delivered voltage, current, or power. The power topology below utilizes a three-phase power-factor–correction AC/DC stage and a phase-shift full bridge (PSFB) isolated DC/DC stage. The AC/DC stage can operate over a wide operating window of input voltages and frequencies, making it easier for end-equipment manufacturers to utilize just two different models globally. Additionally, the DC/DC stage is implemented with a PSFB, which provides controllability across a broader range of output voltages and power levels compared with resonant converters. These two topologies would not be practical to implement with a traditional silicon MOSFET or IGBT, but Wolfspeed SiC MOSFETs are up to the challenge.
Getting Power Closer to the Process
Smaller and more compact power converters offer numerous advantages to manufacturers of semiconductor fabrication equipment. Their high power density allows for placing power supplies closer to the actual tools and processes, resulting in improved consistency and repeatability. However, this proximity also presents challenges that need to be addressed, with converter cooling being one of the most complex issues. The use of forced air cooling is prohibited in clean rooms, making it necessary to find alternative cooling solutions. Astrodyne TDI (ATDI) has a long-standing reputation for providing high-efficiency, liquid-cooled converters designed to tackle this problem and enhance reliability by eliminating the need for fans.
The exceptional switching speed and low conduction losses of Wolfspeed SiC technology have enabled ATDI converters to feature high-switching frequency designs that can operate from a wide range of AC power sources. Wolfspeed's packaging technology has also been pivotal in developing the Kodiak platform's industry-leading liquid-cooled design topology.
The Kodiak platform, resulting from a close collaboration between ATDI and Wolfspeed, goes beyond simply converting existing silicon designs to SiC. It has been optimized with SiC in mind to maximize power density and optimize the overall size. This makes Kodiak an ideal choice for high-power DC systems, particularly in industrial and military applications that require automatic load sharing, a wide DC operating voltage range, international power input, high operating efficiency, excellent reliability, compact size, and easy maintenance.
One of the critical differentiators of Kodiak is its more efficient cooling, which reduces complexity and enhances reliability. The increasing power demands of industrial processes, data processing, communication networks, and military systems have strongly demanded cost-effective and reliable liquid-cooled power conversion systems. ATDI's Kodiak platform addresses this need through its robust and modular approach.
Combining innovative cooling, improved switching capabilities, and reduced size allows for more flexible power converters in semiconductor fabrication tools. The ability to place power supplies closer to the process closes the proximity gap and significantly improves precision, resulting in a direct and positive impact on process performance.
Silicon Carbide-Based Power Solutions Deliver Density and Flexibility
ATDI's extensive range of models offers unparalleled flexibility with fully adjustable outputs and multiple control modes. This reduces the time to market for semiconductor fabrication applications and allows for optimal customization. By harnessing the power density, reliability, output, and design flexibility of SiC in new and innovative ways, ATDI delivers essential power converters for every stage of the semiconductor fabrication process. From the front end to the back end, ATDI's converters provide the perfect solution for all tasks, ensuring efficiency and precision throughout.