xFAB/Pyxis Custom IC Solution
Automated Mentor Flow Quickly Yields High-Quality Portable PDKs for X-FAB
“The Mentor process guarantees a very high quality result”
Thomas Ramsch, X-FAB
Headquartered in Erfurt, Germany, X-FAB is the world’s largest analog/mixed-signal foundry, with the capacity to manufacture approximately 744,000, 200 mm-equivalent wafers per year for mixed-signal integrated circuits. X-FAB is unlike typical foundry services because of its specialized expertise in advanced analog and mixed-signal process technologies, targeted for analog applications that can be integrated with additional functions such as high voltage, non-volatile memory, and sensors.
By combining solid, specialized expertise in advanced analog and mixed-signal process technologies with excellent service and first-class technical support, X-FAB optimally manages the product development flow and supply chain for its customers’ semiconductor products. X-FAB adds further value to the wafer manufacturing process by working with leading EDA suppliers to develop high-quality, fully functional process design kits (PDK), analog and digital IP, and technical hotline support for their customers.
Design kits help companies jump-start their design cycles and cut time-to-market, by enabling the entire design workflow to be supported by foundry-specific processes. The X-FAB team responsible for creating the PDKs wanted to improve the traditional, manual PDK generation process so that they could deliver high quality, fully functional kits to their customers more quickly. With an average of 300 active customers per year doing 1,200 designs—utilizing a variety of EDA tools processes, including different versions of the 180, 130, and 350 nm analog/mixed-signal technologies—such a solution would have a significant impact.
There have always been gaps between the reference toolset and other design environments they are supporting. Their goal was to close these gaps—in terms of quality, productivity, and functionality. They also wanted to speed up the PDK creation process so they could provide kit access to customers even before a new technology was released.
“There are a lot of different technologies and design environments that make having a fast, automated flow and the ability to port the PDK from one toolset to another crucial for supporting this large customer base,” explains Volker Herbig, Technical Marketing Director, X-FAB.
Because of their long history using Mentor tools, including the Pyxis Custom IC Solution, they felt comfortable trying a new PDK creation and QA flow developed by Mentor’s Deep Sub Micron Division. In fact, Mentor delivered an automated PDK generation process that helped them to meet all of their goals.
Closing the Gaps
When it comes to the quality of the kits, there’s a different quality between the golden reference kit and the formerly manually created kits. The manual workflow was more or less specification driven. The devices created would pass normal checks in the design flow, such as design rule check and LVS, but they would not generate a grid-exact layout compared to the reference environment. Their conventional approach was error prone because it was a manual process or certain devices needed to be rewritten.
Also, without further automation, it was almost impossible to test those devices under all conditions that can come up. A consequence of this could be a customer running into a corner case error that was not seen during the generation of the kit and need to contact X-FAB to fix it. This could happen very late in the design cycle and therefore be much more problematic for customers.
The new flow Mentor provided to X-FAB ensures PDK quality through automation and verification. It generates the reference data using the golden reference design environment, and then accelerates the verification of the reference data with the data generated by the converted PDK in the Mentor design environment. This approach also ensures manufacturing grid-exact layout generation.
“Together with the X-FAB QA flow, the Mentor process guarantees a very high quality result at the end of the day,” Thomas Ramsch, Director of Design Support, X-FAB, reports.
The time gap occurs because they had to manually port the reference kits they needed to create to the different design environments X-FAB was supporting. Automation speeds this process significantly. Once they got through the expected effort to learn how to set up and use the new PDK creation flow, they were able to cut the amount of time by half.
“The generation is very fast,” Andreas Klein, Design Engineer, X-FAB, observes. “We needed one month to create one PDK, which is a good time cycle for PDK creation. Manually, it would have taken two months. Now that we’ve done this one time, it should take about two weeks to successfully create a PDK, with the flow working without any errors.”
The third gap has to do with how well the reference and target environments match in functionality. In the past, this was highly dependent on the features provided in the generic device generators. The situation was certainly worse when it came to special devices. Often there were layout generators in the reference kit that worked differently in the customer’s environment.
“With Mentor’s new automated PDK conversion flow, there is no difference in performance between the Mentor environment and our reference environment,” Mr. Ramsch says.
Giving Customers a Head Start
The final goal has to with X-FAB’s new requirement to release the PDKs much earlier than they used to do, even before the technology itself has stabilized and has been released for actual production use. This allows their customers to start earlier in developing their products for upcoming technologies at X-FAB.
“We have alpha and beta PDKs, which reflect certain development stages on the process development side, and we give customers early access to those development programs. This creates a significant need to shorten the transition from one design environment to another, because we are supporting the alpha and beta customers in the design environment they use,” says Mr. Herbig. “The automation of the Mentor flow helps us give our customers a chance to shorten their time-to-market by giving them access to new technology features early.”
Mr. Herbig concludes. “The main benefits of using the Mentor PDK creation and QA flow are that it’s higher quality, it’s not so error-prone, and we are able to cut down the transition time from about two months to about two weeks while maintaining the quality standards of our kits. This is quite an achievement.”
Finally, because X-FAB has a significant number of customers that see Mentor as their favorite design environment, it’s also a benefit for them to provide their customers with a high quality PDK. It’s a win-win situation.
“The automation of the Mentor flow helps us give our customers a chance to shorten their time-to-market by giving them access to new technology features early.”
Volker Herbig, X-FAB
X-FAB is the world’s largest analog/mixed-signal foundry group, manufacturing silicon wafers for mixed-signal integrated circuits.