SECS-GEM for Y2K testing in fabs
12/01/1998
SECS-GEM for Y2K testing in fabs
Jack Ghiselli, Chris Saso, GW Associates Inc., Sunnyvale, California
Potential "year 2000" problems have reached almost mythical proportions. Unfortunately, they have generated excessive studies and pontification. The solution, particularly for semiconductor wafer fabs, involves rolling up our sleeves and fixing the problem.
The potential for "year 2000" (Y2K) problems is found wherever there is software. These include payroll programs, hourly time-clocks, building security computers, and other applications shared across many industries; these applications are well described elsewhere.
Where semiconductor manufacturing is uniquely vulnerable to Y2K exposure is in wafer fabrication capital equipment software and its links to a manufacturing execution system (MES). This exposes both the investment and nature of semiconductor manufacturing:
* In a $1-billion fab, $600 million might be invested in capital equipment. Y2K problems that stop factory operations can be very expensive. The risk of loss is so great that one company is considering shutting down a fab during the 1999-2000 transition.
* Wafer fabs often run 24 hours/day, seven days/week, making it hard to deploy software changes into embedded equipment controllers. Seasonal plant shutdowns are often used for fab changes. In discussions with us, a factory manager at National Semiconductor explained that since December 25, 1999, is "too close to 2000 for comfort," December 25, 1998, is probably the last planned shutdown for equipment suppliers to deploy Y2K software.
Because of past unhappy experiences, many wafer fabs "freeze" software once operations achieve production status. No software changes of any type are allowed in embedded equipment controllers, except in extreme situations. Equipment suppliers have become accustomed to this mode of operation. Now, factories are not only allowing but insisting that equipment suppliers deploy Y2K software fixes, especially in older factories.
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Y2K problems can occur in the newest 300-mm prototype factories, but may in fact be worst in 100-mm and even older factories. The older the equipment, the less likely it is that equipment suppliers still have software "source code," which is usually required for Y2K fixes. Many production systems are actually "one-off specials," whose software documentation is even less likely to have been retained.
On new equipment, suppliers typically offer maintenance support, but for much older equipment, factories have dropped this support, assuming that it was no longer needed. This may also have led equipment suppliers to discard source code. Even if software has been maintained and fabs have received the latest versions, operations managers may have been reluctant to modify a production system and therefore may be running software that is several revisions old. This will surely mean that new Y2K software is likely to have more changes that can affect a fab.
The Y2K issue is so important to the industry that SEMI/SEMATECH has been spreading a "Y2K gospel" by sponsoring several Y2K readiness meetings and providing test scenarios for equipment suppliers and IC manufacturers.
Straightforward testing
The first issue is to determine the existence and severity of any Y2K problems in wafer fab equipment. A typical method used to remediate Y2K issues is "brute force" examination of source code or to use operating system services, such as setting the date from the keyboard and checking for application-software Y2K anomalies. However, most semiconductor manufacturing equipment has a feature that can automate Y2K testing - the SECS-GEM communications link that is typically used for equipment monitoring and control.
This procedure uses a small PC, typically a laptop equipped with automatic Y2K test software (e.g., SECSIM Pro equipped with Y2K testing project - Y2K.Pro [1]) and cabled directly to the SECS-GEM communications port on the piece of equipment being tested. The software is a script-driven tool widely used for a variety of SECS-GEM testing and simulation scenarios.
Such automatic testing is fast. For example, automated Y2K readiness tests run in less than five minutes, compared to an hour or more for manual procedures. The logic in the "Y2K.Pro" tests is taken from "SEMATECH Year 2000 Readiness Testing Scenarios V.2.0" [2], with input from various semiconductor manufacturers.
Assuming a typical wafer fab has 50 types of systems and 400 individual pieces, one test engineer armed with a laptop can test one unit of each type in just over four hours. Counting setup and time waiting for access to equipment, the test engineer might take one week to test an entire fab. If the fab wants each unit tested -for example, if they have different versions of software across several purchases of the same system-it might take a month. The output from such testing is an easy-to-read report (Table 1) that includes the identity of the equipment tested, its software version, and the test results.
Such testing eliminates at least part of the "great unknown" panic aspect of Y2K. We believe that the semiconductor industry needs to put legal issues aside (see "The legal side of Y2K readiness" above), roll up its sleeves, defer writing Y2K environmental impact reports, and actually test the equipment.
Testing for Y2K readiness or compliance?
In the semiconductor industry, Y2K issues related to SECS-GEM communications are defined by SEMI standards E4, E5, E30, E37 and E37.1; these standards include requirements for both Y2K readiness and compliance:
* Y2K readiness determines whether equipment intelligently handles two-digit year formats; does it recognize that 12/31/99 means December 31, 1999, and also recognize that 01/01/00 means January 1, 2000?
* Y2K compliance determines whether equipment handles four-digit year formats defined by SEMI in the February 1998 versions of SECS-II (E5) and GEM (E30). These tests involve SECS-II data items "TIME" and "STIME," a new equipment constant "TIMEFORMAT," and SECS messages "S2F18," "S2F31," and "S6F1" (Table 2).
* Both readiness and compliance are important with Y2K testing because the expediency of semiconductor manufacturing often means that a manufacturer has to accept equipment that still works with only a two-digit year format, just to address the importance of keeping the factory running 24 hours/day, 7 days/week.
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Fixing the problem
* If Y2K testing of your wafer fab equipment shows no problems, you are lucky and can get on to other projects. If you are like the majority of equipment suppliers and users (see "How Y2K-ready are wafer fabs?" page 76), the tests will uncover problems where the next step involves fixing the equipment`s software. To fix the problem, a fab must gain the cooperation of perhaps 50 equipment suppliers. Thus, we believe Y2K problems in embedded equipment controllers represent the longest lead time in the Y2K panoply of problems.
* About 75% of equipment types today implement their SECS-GEM interface using commercial component software products, such as GWGEM. For such equipment, upgrading to Y2K software is straightforward: The equipment supplier upgrades to the latest version of the component software product. Upgrading to the latest Y2K-ready operating system may also be required. For example, one popular equipment controller software operating system platform is SunOS, running on SPARC stations. SunOS v.2.6 is required for Y2K compliance. During our efforts to bring GWGEM up to Y2K compliance, we updated almost all of our 14 supported platforms to the latest versions of the operating system.
* Commercial SECS-GEM software provides many desirable Y2K features:
* Intelligent handling of two-digit year notation allows equipment to work with unmodified legacy host computers, which do not need to be changed, and in some cases cannot be changed. It is desirable that upgrading equipment for Y2K not require any changes to host software. The issue here is practical scheduling. No fab can simultaneously introduce new software on the host and all equipment. Instead, fabs typically introduce new Y2K software on one system at a time, changing the factory host software last. Assuming adherence to new SECS-GEM standards, even Y2K compliant equipment software will work with legacy host systems; with SECS-GEM requirements that equipment accept either two-digit or four-digit year format strings, equipment can be configured to send the two-digit year format.
* Full support for new SEMI standards calls for equipment to handle two- or four-digit formatted years correctly. The Y2K-compliant equipment must automatically distinguish which type of date is sent by the host, and must accept both types. Equipment must be configurable so a given factory can set an equipment constant (via the SECS-GEM link or via the equipment`s operator interface) to control whether the equipment should send two- or four-digit years as desired by the factory host.
* Support for the two-digit "silver bullet" year, 1972. Some older host computer software cannot be changed. In such cases, some factories choose, seemingly, to "run the factory in the past." This approach takes advantage of a quirk that the "shape" of the year repeats every 28 years. That is, January 1 is a Saturday in both 1972 and 2000 and both years are leap years. Similarly, 1973 is like 2001, etc. If host software cannot be changed, perhaps a factory can perpetually trick systems so the numeric day and all day-of-the-week computations will be correct. Date stamps will be 28 years old, but this is such a large and easily recognized error that often it can be detected and corrected manually or by conversion programs. At any rate, well-designed commercial SECS-GEM software in equipment should support 1972 as a 2-digit year. Unfortunately, some operating systems cannot support this. For example, most MS-DOS platforms cannot set a date earlier than 1980.
* Commercial Y2K compliant SECS-GEM software is available for most popular operating system platforms, including Windows NT, Windows 95 and 98, OS-2, MS-DOS, UNIX, OS-9, VxWorks, QNX, and others.
Who pays?
It is not clear who will pay for bringing equipment to Y2K readiness and compliance: equipment suppliers or user factories?
In either case, based on past experience, many factories worry that equipment suppliers will introduce unwanted, unrelated software changes and sometimes even software errors when making Y2K SECS-GEM software available to their customers. This will undoubtedly increase the cost of Y2K equipment controller integration.
It is clear, however, that Y2K is one software project with a deadline that cannot slip. January 1, 2000, will arrive on time. Let`s get to work and fix the problem. n
How Y2K-ready are wafer fabs?
To understand the magnitude of Y2K problems in wafer fabs and the way different companies are establishing their readiness, Solid State Technology spoke with key contacts at selected semiconductor manufacturers.
First, we found a degree of legal paranoia. Many messages to reliable sources were answered by a corporate lawyer. It seems clear that as the world begins the new digital millennium countdown, legal protection is every bit as important as a technical solution.
From those in wafer fabs who did talk to us, we found that for an industry where difficult problems are at the cutting edge of process technology, achieving Y2K readiness is more a "mechanical nuisance" that requires strong management rather than development of unknown solutions.
Doron Simon, director of planning for Tower Semiconductor, said, "Once we recognized it was more than just an information systems [IS] department issue, Y2K became an important project management task rather than just a development or maintenance task. Leadership is driven by senior management; everyone is aware of the project and IS is an important consultant and participant in our effort."
At many semiconductor fabs, it seems that successful Y2K projects must be managed very much like ISO standardization efforts, where it is "know what you do, do what you say, and document it." It is very likely that come January 1, 2000, the companies with Y2K problems will be those that have failed to get ISO standardization efforts started. It is not that an ISO-standard label is so important, but the process of ISO standardization creates a corporate atmosphere, beginning at the top, where the issue at hand requires an enterprise-wide, executive-led effort.
Quincy Lin, a VP at TSMC, told SST, "Y2K is a company-wide project, requiring company mobilization. The hardware and software that may go wrong exists in every corner of the company, and includes fab equipment, computers and networks, commercial software, and many in-house developed programs." Lin is the project owner and executive secretary of TSMC`s Y2K steering committee, which is led by the company president and includes all VPs.
As a good measure of the mechanical scope of a Y2K project in semiconductor manufacturing, TSMC has 800 equipment types with about 3000 individual units in wafer fabrication. Lin notes, "It is important to distinguish between equipment types and units. Readiness depends on the type, but deployment cost depends on the number of units." TSMC`s IS infrastructure of PCs, servers, and network devices has 160 types and 700 units, two-thirds of which are PCs. For software, TSMC uses 100 commercial programs and close to 10,000 internally developed programs.
From SST`s interviews, it seems that most semiconductor manufacturers are on a schedule where inventory has been completed; unit testing will be completed by the end of 1998; and situation testing will be done by February 1999 with deployment by April 1999. This schedule implies that equipment suppliers have been able to pinpoint a readiness date: ready now or ready by a given date. "Some small vendors have told us that they don`t have a solution," says Lin.
An overall measure of the readiness of the semiconductor manufacturing industry is difficult to achieve. Providing one point of view, Harvey Wohlwend, SEMATECH`s Y2K readiness project manager routinely surveys the consortium`s 15 member companies, using information based on input from equipment suppliers. As of September 30, of 8500 wafer fabrication tools that had been identified, 1100 (13%) were Y2K compliant, an additional 550 (6%) had an upgrade available, 1050 (12%) had an upgrade in development and testing, and 140 tools (<2%) have been identified as "never ready" (i.e., older tools no longer supported by the supplier). Wohlwend said, "We have concentrated our efforts on suppliers who support two or more of our members."
TSMC, one of the top 10 semiconductor manufacturers measured in wafer output, provided SST with an even more comprehensive analysis. In mid-October, its inventory of wafer fab equipment revealed:
* 59% of the equipment manufacturers stating that their equipment is Y2K ready;
* 36% stating they will have a readiness date soon; and
* 5% stating they don`t have a date or they don`t know how to solve the problem (in some of these cases the supplying companies no longer exist).
Lin adds, "The readiness status with our IS equipment infrastructure is much higher, about 95% with 5% of these suppliers promising a date soon. With commercial software, 53% of the suppliers are ready now; 15% have a date; and the remaining 31% will have a date in the future. Because we are doing the readiness of our in-house applications, 100% of these have dates."
TSMC`s in-house testing using SEMATECH`s 31 test scenarios revealed that some vendors were not Y2K-ready even when they stated they were. These tests include application of operational dates from 12/1/1999 into 2000, testing the leap year specific date of 2/29/2000, checking the validity of system-generated reports, and shutting a system down once a 2000 date is simulated to see if it will re-start.
"We found that approximately 10% of the wafer fab equipment suppliers were not really ready when they said they were," said Lin. "This is a problem and an important issue that drives us to test every piece of equipment. It is also an important message for other companies who may be inclined to take statements of readiness on face value."
Providing another view, that of MES Y2K compliance, Shantha Mohan, VP of software development at Consilium, said, "By the end of the year, when many fabs are planning Y2K readiness implementations during planned shutdowns, we expect to see approximately an 80% readiness with MES systems."
Julian Mott, Y2K project manager at Siemens, says, "The state of readiness has a risk factor. However, the known steps of inventory, assessment, planning, and deployment of fixes steadily reduces this risk." Despite reports that the semiconductor industry has not taken Y2K readiness seriously, most semiconductor manufacturers have. Indeed, for an industry that changes so dramatically even on a yearly basis, many see the "event horizon" at around six months (i.e., mid-1999). Even closer, dramatic changes in readiness evaluations are expected, following planned shutdowns before the end of 1998. - P. B.
Acknowledgments
SECSIM Pro and GWGEM are registered trademarks of GW Associates. SunOS and SPARC are registered trademarks of Sun Microsystems.
References
1. Y2K.Pro is available free at http://www.gwainc.com/y2k.htm.
2. Available at www.sematech.org/public/division/mm/y2k/testscen.htm.
JACK GHISELLI is president of GW Associates and has 30 years of experience in software design and development. He has been active in SEMI standards development since 1979, and currently serves as vice chairman for SEMI`s North America Information and Control Committee, which is responsible for the SECS-GEM standards. GW Associates Inc., 1183 Bordeaux Drive, Suite 27, Sunnyvale, CA 94089-1201; ph 408/745-1844, fax 408/745-6395.
CHRIS SASO has worked in the semiconductor industry for more than eight years. He has extensive background in factory automation, applying SECS-GEM communications standards during his work at Watkins-Johnson. At GW Associates, Saso provides technical support, training and product-requirements generation, currently focusing on Y2K issues and new product development.