Extending STDF capability


Here in yieldHUB, we work with customers to solve problems in new ways, as well as providing software to help yield management. Xaar, one of our customers in the UK, needed to extend the capability of STDF to avoid changing software on the test floor. We work with STDF a lot. We were happy to help them with the challenge. It turned out to be rather interesting, so we thought we’d share it with you here.


Standard Test Data Format (STDF) is a file format for semiconductor test information. It was developed by Teradyne. It is now a de facto standard widely used throughout the semiconductor industry. It is a commonly used format produced by automatic test equipment (ATE) platforms from companies such as LTX-Credence, Roos Instruments, Teradyne, Advantest and others.

It is the preferred file format for semiconductor test information. It is very useful for bringing together many results or data-points in semiconductor or electronics testing. Having a standard means that all vendors can work to that standard but it also means that not all needs are catered for.

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The challenge

We’ve seen a number of customers who want to view results in a different way. They want to see the relative physical location, of the parts of the chip, where the results come from. The simple case is the pins on a device. STDF has pin records. It stores pin numbers, pin names, and results per pin. However, there is no facility to record the physical location of each pin. As it isn’t in the standard, it is not easy to add it into the test data at source. So we have added the option to include this into the data analysis tool, yieldHUB. While pins on a device is the most common need for this, some of our customers have more complex and interesting examples. One of these is Xaar.

The customer

Xaar is a world leader in industrial inkjet technology. They are a large fabless company and we’ve been working together for a few years.

Xaar’s unique challenge

Xaar designs and manufactures inkjet printheads. The nozzles on the printhead are tested a number of times during manufacturing. The physical location of any variation in performance is very useful to assess. Using yieldHUB, Xaar engineers are able to see map images of where the tens of thousands of nozzles are across a silicon wafer and how these differ. This means that variation from the wafer fab can be identified and improved when necessary.

The outcome

The solution worked seamlessly for Xaar. Leading the work within Xaar is Principal Product Engineer, Alan Morgan. Alan says “With the addition of MPR XY Mapping in yieldHUB, I am able to do extremely detailed analysis very quickly. This helps me to understand silicon variation and how it can affect the performance of critical components in the printhead. At Xaar, we pride ourselves on delivering the highest quality and performance to our customers. We’re excited to extend analysis capabilities beyond standard formats such as STDF without needing to change any software on the test floor.”

Kevin Robinson, Director of Customer Success in yieldHUB had this to say about delivering new capabilities to customers, “This project is a great example of what we deliver to our customers. We work closely with them to understand their needs and then bring real value and unique insights to our customers. Providing new capabilities that unlock new insights for our customers into their manufacturing is both exciting and satisfying.”

The images below are taken from yieldHUB to show some of the capability. Image 1 shows how the average parametric result varies across a wafer maps looks with a small number of die per wafer. Image 2 shows the MPR XY mapping with data from thousands of nozzles (could be pins, pixels, repeated design blocks) mapped across the die and wafer. Image 3 is a gallery of a 25 wafer lot. Here you can see the variation wafer to wafer in the patterns. yieldHUB also supports stacking thousands of wafers for even deeper analysis.


Why is this important?

Like many companies, Xaar had a unique challenge. By working together, we were able to come up with an interesting solution. It is easy to see challenges as insurmountable, but the old adage “Ask and you shall receive” holds true. When you work with your suppliers, they may have seen your challenge many times. They will undoubtedly have a different perspective on the situation and might come up with a novel solution for you. If you work for a fabless company, IDM or OSAT and have a challenge that you think is unique, contact us. The solution might be a lot easier than you think.

About yieldHUB

yieldHUB is a multinational company specializing in Yield Management Solutions for the semiconductor industry. For companies who need to optimize yields, yieldHUB software provides them with a complete understanding of yields in manufacturing. Advanced offerings include specialist software for aerospace, automotive and AI chips.

Visit www.yieldhub.com

About Xaar PLC

Xaar is a world leader in the development of digital inkjet technology. Xaar’s technology drives the conversion of analogue printing and manufacturing methods to digital inkjet which is more efficient, more economical and more productive than the traditional methods which have been in use for years.

The company designs and manufactures printheads as well as systems for product decoration and industrial 3D Printing which use its inkjet technology.