What are the power semiconductor design challenges?

Jessie February 21, 2024

Efficiency is at the heart of today's chip design, especially for electric vehicles (EVs), renewable energy, cloud computing and mobile applications. It's not hard to see why reducing energy loss can have huge benefits. For example, in electric vehicles, we can experience shorter charging times, faster acceleration, longer driving range, and so on, and these advantages are rooted in efficient power devices.

Power semiconductor devices are the backbone of power management systems. They are commonly used as switches and rectifiers, capable of changing voltage or frequency. Since they are designed to run on, the goal is to optimize their use in that mode.

In addition to efficiency, power devices provide a regulated power supply to a system or integrated circuit (IC), ensuring more reliable operation. The quest for greater efficiency and reliability creates the need for larger devices, which increases costs and time to market. This is one reason why power device designers are turning to silicon carbide (SiC) and gallium nitride (GaN); These materials have lower resistivity and can achieve greater efficiency in smaller packages.

The biggest challenge in designing power semiconductor devices

Not surprisingly, efficiency is both the most important metric for power devices and the biggest challenge. The driving force of efficiency is mainly measured by the on-resistance of the device. In addition to efficiency, several other challenges require attention, including:

• Current density: Ensure the design complies with electromigration (EM) rules

• Device on/off delay: Ensures that the entire device opens within a defined time window

• Switching loss

Although the design size is constantly increasing, the main goal is to drive the maximum current through the smallest possible area. This has the potential to cause electromagnetic problems and make the design unreliable. Identifying these problems and solving them without other effects is one of the major challenges in power device design.

Therefore, dealing with the complexity and size of large designs, especially SiC designs, has become an important factor. Designers must consider the high switching frequency characteristics of these designs and their dimensions. The large size of these designs means that the gate signal (the trigger that the device activates) may take longer to propagate throughout the structure. This delay can cause some parts of the device to activate before others, resulting in uneven current distribution, higher current density, and potential reliability issues.

As we move deeper into larger, more efficient designs, switching losses have become a significant factor in efficiency losses. Integrated device manufacturers can alter and enhance transistors, giving them more flexibility than fabless companies, which typically can only use transistors supplied by foundries. Since this is a transient problem, a detailed analysis is needed to understand the impact of switching. Understanding the overall impact of changes, especially the complex routing inherent in large devices, is critical, and the ability to visualize and compare the impact of multiple similar layouts becomes an important element in overcoming these challenges

Syrs' Power Device Workbench solution ensures maximum efficiency and reliability in evolving power semiconductors.

Why Power Device Workbench?

Power Device Workbench (PDW) is the leading tool for the power device market. PDW has been used to optimize the design of all technical nodes down to 4nm and is especially helpful for large designs. Once the initial layout of the design is available, the designer applies PDW, which seamlessly accompanies the development process until the design is approved.

When designers are looking for tools to optimize power transistors and electronics, the most important factors include the ability to improve efficiency, quickly compare different designs and enhancements, review different wiring schemes, optimize redistribution layers (RDL), and quickly correct electromigration (EM) violations.

PDW's core capability lies in its ability to analyze and simulate complex details of power devices in detail and speed. The tool focuses on resistance and current within complex metal interconnects. By employing a high-throughput simulation engine, PDW enables engineers to optimize key design parameters such as metal layout and bonding line configuration, as well as analyze the complete grid network, which is extremely difficult in large complex designs. This allows products to be brought to market faster.

PDW main features

The Power Device Workbench provides a set of key features that enhance its functionality and differentiate it from other tools in the field.

Analyze designs of various sizes: PDW excels at handling designs of various sizes, going beyond the limitations of many other tools. Its capabilities extend to address all types of cabling complexity, giving designers a complete understanding of on-resistance. This insight becomes the basis for targeted improvements that ultimately improve the overall efficiency of the power device.

Full grid network processing: For large circuits, PDW takes center stage by seamlessly processing full grid networks. This is essential to ensure that the entire unit is turned on in a very short period of time, which is a key factor in meeting reliability objectives. By identifying specific areas of the network that need to be enhanced, PDW can help designers optimize the reliability of large circuits.

Package processing: PDW goes beyond the chip itself to include the design package. In efficient design, packaging plays a key role. PDW navigates the redistribution layer within the package, connecting it to chip locations with wider metal and helping to increase efficiency. In addition, PDW helps optimize the sensor layout in the design, ensuring the correct operation of the power device through thermal sensor and current sensor positioning.

Automatic correction of electromigration violations: When the current density within the design exceeds acceptable limits, PDW accurately identifies what is happening and specifies the actual value of the metal layer and current density. It then automatically rewires the design, eliminating electromagnetic issues and ensuring compliance with design standards.

Comprehensive design optimization: Whether it's improving on-resistance, optimizing gate networks for timely activation, enhancing RDL in packages, or exploring design areas to achieve specific resistance goals, PDW offers a multi-dimensional approach to optimizing power devices.

Automatic comparison of design differences: An outstanding feature of PDW is its ability to automatically compare design differences. As designers make changes, PDW quickly assesses the impact on the overall performance of each layer. This ability is invaluable for understanding the global impact of local modifications, enabling designers to make informed decisions that positively impact the overall design.

Integration with PrimeSIM: Since switching losses are transient effects, PDW created the distributed device model used by PrimeSIM. PDW can display the current and voltage diagram of the design at any time during the transient simulation.

Ultimately, PDW speeds up the optimization process, delivering high-quality results in a short amount of time. PDW serves not only as a tool, but also as a catalyst for innovation, giving engineers ways to push the boundaries of power device efficiency and reliability. As technology continues to evolve, PDW is always at the forefront, ensuring that power devices are not only designed, but optimized for maximum efficiency and reliability.

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