Case Study: Semiconductor Design Analysis in Express

For more than 15 years, the TCAD Division of Avant! has provided physical simulation software to support the design and manufacture of integrated circuits.

The semiconductor design and manufacturing process has changed radically since the first integrated circuits appeared in the late 1950s, and at this point has grown too complex for engineers to rely on experimental techniques alone. The modern semiconductor manufacturer employs process and device modeling programs to shift concerns of manufacturability, reliability and performance to the earlier stages of the design process so that most issues are resolved long before the first prototype is manufactured.

This image shows potential electrical distribution in an SRAM integrated circuit, produced by Rafaelª, Avant! TCAD Division's IC interconnect simulator.

These programs greatly reduce design time and cost, leverage design talent, and ultimately, get products to market faster. At the same time, however, the ever-shrinking geometries of integrated circuits increases the impact of device physics on circuit performance. Understanding these effects at the "deep sub-micron" level is key to success of new circuit designs. And now, with Avant's Taurus-Visual software – developed with AVS/Express – design physicists can see the results of simulation in 3D.

"We needed to have a way to develop visualization of the results of 3D simulations. We decided to seek an outside vendor for this visualization software because it's not in our best interest to develop 3D algorithms. It's not our expertise. We are physicists," said Tony Slocum, manager of the System and Utilities Branch, Engineering and Development at Avant!. "We chose AVS because it has more versatility than others," he added. "And that was very important to our goal of providing easy-to-use products with interfaces that incorporate the highly specific, precise terminology used by scientists in the field.

"We wanted the visualization software completely embedded in our software environment. We wrapped our interface completely around the visualization tools. Visual has to operate as a library of visualization routines so users simply select the options they want," Slocum said. "AVS/Express let us make the product very flexible, and it gave us the engine power we needed: some files that the simulators produce are up to 28MB of pure data!"

Avant!'s physical simulation software models fabrication of next-generation wafers and the electrical properties of resulting transistors and other electrical devices. Process simulators model each step in the process recipe, from diffusing dopants into the silicon to etch and deposition steps to add metal layers for conductors. The result is a 2D and 3D virtual wafer that can be visualized using Avant!'s AVS/Express-based product, Taurus-Visual.

"Taurus-Visual allows semiconductor manufacturers to reduce the time required to design next-generation technology and to save costs by minimizing the number of experimental runs required by the fabricator. The AVS/Express software brought two primary advantages that helped us quickly bring a full-capability 3D visualization product to market," Slocum said. "The first is the AVS/Express library of visualization modules that can be assembled in flexible ways to satisfy unique application requirements. The second is the object-oriented software engineering environment that allows developers to quickly prototype and test the embedded AVS/Express modules within the application code."