Using Ansys Charge Plus to Support the Growing Semiconductor Industry

Whether you’re reading this on your computer or your phone, a semiconductor is involved.

Semiconductors are an essential component of electronic devices. Also known as microchips, they control and manage the flow of the electric current in electronic equipment and devices. Thanks to developments in the semiconductor industry, electronics are now smaller, faster, and more reliable. They are found in computers, smart phones, vehicles, and gaming devices. In these devices, semiconductors are largely used for memory, logic, analog, and microprocessors.

The Semiconductor Industry Association (SIA) says there are more than 100 billion integrated circuits in daily use around the world. That number is equal to the number of stars in the Milky Way galaxy. A single semiconductor chip has as many transistors as all of the stones in the Great Pyramid of Giza SIA says.

Semiconductor Industry Growth

The semiconductor industry is a key growth sector in the global economy. According to the latest numbers from SIA, worldwide sales have increased from $139 billion in 2001 to $574 billion in 2022. The World Semiconductor Trade Statistics (WSTS) Fall 2022 Semiconductor Industry Forecast does expect to see sales decrease in 2023 to $556 billion but jump again in 2024 to $602 billion.

Fig 1. World semiconductor industry sales from 2001 to 2022.

(Courtesy: Semiconductor Industry Association)

The U.S. semiconductor industry holds nearly half of the global market share, at 48% in 2022. The U.S. is followed by Korea with 19% and Japan and the European Union, each with 9%. Numbers from SIA show that sales from U.S. based semiconductor firms grew from $71.1 billion in 2011 to $275 billion in 2022.

Fig. 2. U.S.-based semiconductor company sales.

(Courtesy: Semiconductor Industry Association)

Semiconductors are a big export for the United States. Exports were worth $61.1 billion in 2022. This makes microchips the fifth-highest U.S. export behind refined oil, crude oil, natural gas, and aircraft. Semiconductors make up the largest share of U.S. electronic product exports followed by radio and TV broadcasting and wireless communication equipment, computer equipment, computers, and electromedical devices.

Fig. 3. Top five U.S. exports in 2022.

Research and Development

Research and development expenditures are essential to be competitive in the semiconductor industry. SIA reports that annual R&D expenditure as a percent of sales has exceeded 15% over the past 20 years. This makes semiconductor R&D as a percent of sales second only to pharmaceuticals and biotechnology.

Fig. 4. R&D Expenditures as a Percent of Sales.

Part of research and development includes predicting charged plasma behaviors of semiconductors during the design process. This is possible with the simulation software tool Ansys Charge Plus.

Using Simulation

Charge Plus is a multiphysics software simulation tool that provides the capabilities needed to simulate and predict charged plasma behaviors with particle-in-cell (PIC) solver technology. The solvers create rapid and accurate simulations of electromagnetic (EM) phenomena that cannot be modeled using analytical equations alone. The PIC technology makes it possible to track particles across a numerical mesh and allows users to visualize, predict, and monitor plasma behavior quickly and accurately. Coupled with a full-wave EM solver, the PIC solver effectively connects plasma phenomena with EM physics. Integration with additional Ansys simulation tools, including Chemkin-Pro, bridge the gaps throughout the process.

Using Charge Plus saves designers time and cost on current projects. It helps the user better prepare and design future products through virtual prototyping, predictive accuracy, and EM modeling.

Simulating Semiconductors

Two of the ways the semiconductor industry leverages the multiphysics found in Charge Plus are plasma enhanced chemical vapor deposition (PECVD) and plasma etching.

Here we will take a look at PECVD, which is a technique that uses plasma to deposit thin films of material onto semiconductor surfaces. The process is commonly used to create insulting layers and high-quality films for various semiconductor applications. To do this physically, a chemical with free radicals is placed on the surface of the wafer and then the wafer is placed in a plasma chamber. Plasma may be generated from an ambient gas by driving a radio frequency (RF) source. The ions in the plasma interact with the surface of the wafer and the interaction with the radicals create byproducts. The influx of ambient gas and the outflux of byproducts is handled through valves that control the ambient flow of gas.

This process can be sped up and done early in the development process by using Charge Plus for simulation. This is made possible with various engineering disciplines found in the tool, including:

• Fluid mechanics to model the gas motion in the chamber
• Electromagnetics to model the RF source and the field interactions with the plasma
• Plasma physics to generate and track the plasma dynamic near the wafer
• Chemistry for the interaction of the ions at the surface of the wafer

A challenge emerges because deposition rates rely heavily on the rate of collision between the ions in the plasma and the surface of the wafer. To tackle this simulation, the PIC models relativistic collisions within a species and between multiple species. The plasma distributions created by the PIC generate EM fields that are captured by the full-wave finite element method (FEM) solver.

PECVD Workflow

To complete the PECVD workflow, the PIC and FEM solver are integrated with Ansys Fluent and Chemkin-Pro to begin computational fluid dynamics (CFD) and chemistry simulation.

Figure 5 is a look inside of a PECVD chamber showing the electron dynamic based on an RF source placed in the system. These post-processing capabilities are possible thanks to integration with Ansys Ensight. Using Ensite the user can look at the density enhancement in the system, temperature distributions, and the flow of the fluid in the chamber due to settings that are set at the initialization of the simulation.

Figure 5. Example of electrons pulsing and the density changing based on the EM forces exerted on the system.

Conclusion

As technology advances, semiconductors will continue to be a vital part of development. A key to being competitive is making sure designs are correct the first time around, this is where Charge Plus steps in. Using simulation to take a closer look at semiconductors allows designers to create a functional microchip for their product within budgeted time frames and costs.

To learn more about Charge Plus and its PIC solver, click here. EMA is available to support your projects and help you find answers to any questions you may have. You can reach us here.

Charge Plus is maintained by EMA and sold exclusively through Ansys. If you are interested in purchasing the software, you can click here.