What are the design challenges for power semiconductors?

Efficiency is at the heart of today's chip designs, especially for applications in electric vehicles (EVs), renewable energy, cloud computing and mobility. It’s not hard to see why reducing energy loss can bring huge benefits. For example, in electric vehicles, we can experience shorter charging times, faster acceleration, longer cruising range, etc. The root of these advantages lies in efficient power devices.

Power semiconductor devices are the workhorses of power management systems. They are often used as switches and rectifiers, capable of changing voltage or frequency. Since they are designed to operate in the on state, the goal is to optimize use in this mode.

In addition to efficiency, power devices provide regulated power to a system or integrated circuit (IC), ensuring more reliable operation. The pursuit of greater efficiency and reliability creates the need for larger equipment, thereby increasing costs and time to market. This is one reason power device designers are turning to silicon carbide (SiC) and gallium nitride (GaN); the lower resistivity of these materials allows for higher efficiencies in smaller packages.

The biggest challenge in designing power semiconductor devices

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

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

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

• Switching losses

Although design sizes continue to increase, the main goal is to drive the maximum current through the smallest possible area. This has the potential to cause electromagnetic problems, making the design unreliable. Identifying these issues and resolving them without other consequences 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 size. The huge size of these designs means that the gate signal (the trigger that activates the device) can 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 densities, 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 change and enhance transistors, giving them more flexibility than fabless companies, which typically can only use transistors provided by foundries. Since this is a transient problem, detailed analysis is required to understand the effects 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 critical in overcoming these challenges.

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

Why choose Power Device Workbench?

Power Device Workbench (PDW) is the leading tool for the power device market. PDW has been used to optimize designs at all technology nodes down to 4nm, and is especially helpful for large designs. Once the initial layout of the design is available, designers apply PDW, seamlessly accompanying the development process until the design is signed off.

When designers look for tools to optimize power transistors and electronic devices, the most important factors include improving efficiency, quickly comparing different designs and enhancements, reviewing different routing schemes, optimizing redistribution layers (RDL), and quickly correcting electromigration (EM). ) the ability to violate the rules.

The core capability of PDW lies in its ability to analyze and simulate the intricate details of power devices in detail and quickly. This tool focuses on resistance and current flow within complex metal interconnections. By employing a high-throughput simulation engine, PDW enables engineers to optimize key design parameters such as metal layout and bond wire configuration, as well as analyze the complete gate network (which is extremely difficult in large, complex designs). This allows products to be brought to market faster.

Main features of PDW

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

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

Full Gate Network Handling: For large circuits, PDW takes center stage by seamlessly processing full gate networks. This is essential to ensure that the entire device is switched on within a very short time, which is a key factor in meeting reliability targets. PDW can help designers optimize the reliability of large circuits by identifying specific areas in the network that need enhancement.

Packaging processing: PDW goes beyond the chip itself to include design packaging. In high-efficiency designs, packaging plays a key role. PDW navigates redistribution layers within the package, connecting it to chip locations with wider metal and helping improve efficiency. In addition, PDW helps optimize sensor layout in the design, ensuring correct operation of power devices through thermal and current sensor positioning.

Automatically correct electromigration violations: When current density within a design exceeds acceptable limits, PDW pinpoints what is happening and specifies actual values ​​for metal layers and current density. It then automatically rewires the design, eliminating electromagnetic issues and ensuring compliance with design standards.

Comprehensive design optimization: Whether improving on-resistance, optimizing the gate network for timely activation, enhancing RDL in the package, or exploring design areas to achieve specific resistance targets, PDW provides a multi-faceted approach to optimizing power devices.

Automatic comparison of design differences: A standout feature of PDW is its ability to automatically compare design differences. When 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, allowing designers to make informed decisions that positively impact the entire design.

Integration with PrimeSIM: Since switching losses are transient effects, PDW creates distributed device models used by PrimeSIM. PDW can display the design's current and voltage diagrams at any time during transient simulation.

Ultimately, PDW accelerates the optimization process, delivering high-quality results in a fraction of the time. Not only as a tool but also as a catalyst for innovation, PDW provides engineers with the means to push the boundaries of power device efficiency and reliability. As technology continues to evolve, PDW remains at the forefront, ensuring that power devices are not only designed, but optimized for maximum efficiency and reliability.