Thinking out of the box: Expanding STC's impact with STIX (Guest commentary)
Steve Wigley, Semiconductor Test Consortium and LTX -- Test & Measurement World, 11/2/2007 6:08:00 AM
Since its founding in 2003, the Semiconductor Test Consortium (STC) has worked to develop and implement value-added open test standards for the benefit of the semiconductor industry. The majority of these efforts in the past were focused on the OpenStar initiative, which looked to develop an open semiconductor test architecture with the goal of lowering test costs. In response to calls from its membership as well as the industry at large, the STC expanded its scope earlier this year to include the interfaces that surround the tester with the launch of the Semiconductor Test Interface eXtensions (STIX) initiative. This article discusses the details of the STIX initiative, its potential impact on the semiconductor test supply chain, and its effect on the STC.
ATE peripheral interfaces
To fully understand the potential impact of the STIX initiative, it is important to look at the pieces that make up an ATE work cell (see figure at bottom of page). Typically, an ATE system in a high-volume manufacturing environment will interface to many peripheral systems and processes, such as handlers, probers, operator interfaces, design tools, and manufacturing process-monitoring tools.
In the past, there have been a variety of efforts to standardize these interfaces. Examples include the Standard Test Interface Language (STIL), which allows transfer of digital test vectors from design databases to testers, and GEM/SECS, which is used in factory automation. However, in most cases these interfaces are custom in nature. This means engineering effort is often spent to solve the same problems over and over again at different semiconductor manufacturers.
Despite the obvious value these interfaces bring to overall semiconductor manufacturing test process, developing these custom interfaces is viewed as “zero cost.” Semiconductor manufacturers, ATE suppliers and peripherals vendors will typically work together to put in place the necessary custom interfaces without taking into account the cost of this effort. It just becomes part of the normal ATE user and supplier relationship. However, there are significant hidden costs associated with developing and maintaining these interfaces.
The STIX initiative
In 2007, the STC launched the STIX initiative with the goal of addressing rising cost and efficiency challenges through the development of ATE peripheral interface standards. This marks a significant expansion to the scope of the STC, as previous efforts focused solely on tester architecture, while the STIX initiative encompasses the entire test process and treats the tester as a non-architecture specific black box. The STIX initiative will look at hardware and software specifications for all the peripheral areas around the ATE, regardless of tester architecture or vendor.
Key to the STIX initiative is the formation of technical, industry-driven working groups to address these peripheral areas. Currently, there are three key working groups:
• the STIL group focuses on the industrialization of STIL by looking at format validation suites and software object model development,
• the docking and interfacing group focuses on defining a common interfacing ”language” with a view to move into interface specifications, and
• the probe cards group focuses on defining the critical dimensions to enable common tooling designs of such items as prober top plates.
Moving forward, additional technical working groups will be formed to address such topics as user level API, instrument abstraction layer, tooling abstraction layer, asynchronous test interfaces, datalogging interfaces, test-program generation, and EDA diagnostic interfaces.
Impact on ATE users and the ATE supply chain
But what does the STIX initiative really mean to ATE users and the ATE supply chain? In short, the initiative offers the opportunity to reduce development costs as well as overall operational costs.
• Reduced development costs: The STIX initiative offers the potential to remove or significantly reduce the costs associated with providing ATE peripheral interfaces. Over time, it will enable semiconductor manufacturers to focus all their engineering efforts on processing the data from the interfaces and the valuable information that data provides, rather than defining, developing, and supporting the interfaces themselves. Just as importantly, STIX offers the opportunity for the ATE supply chain to eliminate redundant research and development (R&D) efforts in non-differentiating and non-revenue generating product areas.
• Reduced operational costs: By standardizing these interfaces, semiconductor manufacturers can benefit by gaining higher equipment utilization and lower cost of change when moving to new platforms or processes. With electrical, mechanical and software interfaces standardized across the various elements making up a test cell, operating costs will be reduced. Operators’ change-over procedures will be significantly simplified because of commonality of docking and interfacing between various elements in the test cell. This will lead to shorter and more efficient changeovers improving the overall availability of the test cell.
Impact on the STC
The introduction of the STIX initiative is a critical step for the STC. It dramatically increases the potential positive impact of the consortium on the semiconductor industry, by extending its influence beyond simply the tester architecture. It represents a more holistic approach to addressing the technical and economic issues that affect the entire global semiconductor test supply chain. This approach has broadened the appeal of the STC over the past 12 months, and has been an important factor in expanded involvement from over 30 new companies, individuals, and universities.
One such company who has expanded its involvement with the STC as a direct result of the STIX initiative is LTX, which had limited involvement with the STC until the STIX initiative. Because of the potential advantages of standardized interfaces—both to its customers and to its internal development efforts—LTX decided to become more actively involved in driving the STIX initiative. The first step in this process was my acceptance of a nomination to the STC board of directors and the STC membership’s subsequent approval of that nomination. With representation on the STC board, LTX has become a key driver of the new STC initiatives.
As noted, the STIX initiative is a significant shift for the STC. The focus is now driving industry to define new standards and processes that will reduce the overall cost of operating a complete, integrated test cell. It does not place any emphasis on architecture or the ATE used in the test cell. This will allow semiconductor manufacturers and the ATE supply chain to take full advantage of these new efforts, regardless of whether they are applying them to legacy or new ATE systems, existing handlers or probers, or any other peripheral equipment or process. The broader appeal of these new efforts has sparked new interest in the STC, and has resulted in growing industry participation in this effort.
Steve Wigley serves on the board of directors of the Semiconductor Test Consortium and is VP of product marketing at LTX.
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ATE systems in high-volume manufacturing environments will interface to many peripheral systems and processes.
Read related guest commentary, "The need for new ATE interface standards," by Klaus Luther of Infineon Technologies.
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