TI Blitzes to Improve Fab Productivity
Texas Instruments Inc. has used rapid improvement events, or kaizen blitzes, to sharply improve productivity at the DFAB in Dallas. TI also incorporated a "5S" program to "get the junk out," fab manager Steve James said in a keynote speech at the ISMI Symposium on Manufacturing Effectiveness. Other speakers at the annual symposium detailed the importance of preventive maintenance techniques.
David Lammers, News Editor -- Semiconductor International, 10/29/2008 9:47:00 AM
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| Steve James, Texas Instruments |
“We Americans want to believe that people from other cultures are more disciplined,” James said. For TI, the challenge was to learn from best practices around the world, he said, adding, “TI wasn’t so good at sharing among its factories.”
Most of the blitzes occurred among workers at the company’s leading-edge DFAB in Dallas, involving groups of perhaps a dozen workers from a production unit gathered together for two or three days. One unit blitzed on ways to improve maintenance techniques and productivity by technicians. After several days, they had agreed on a list of new procedures, including a pared-down list of preventive maintenance procedures that were more readily understood and accomplished, he said.
Asked if management was willing to approve the overtime pay often involved with the off-site meetings, James said costs are certainly an issue in the current economic environment but added that thus far management has agreed that the extra expense is outweighed by productivity enhancements. He said productivity at DFAB has gone up ~40% since the programs started in 2005. Two on-site staffers spend much of their time organizing the blitz events.
TI’s Hiji fab in southern Japan has led the way in improving productivity, winning a Deming Award in the early 1990s. “The Hiji fab went from worst to best in its overall metrics,” James said, leading fab managers in Dallas to investigate how the Hiji workforce had pulled off what was seen among the Hiji workers as a fab survival effort.
The Hiji workforce implemented a “5S” program, based on five Japanese words that begin with the letter S, developed by Japanese management consultant Hiroyuki Hirano. James said a crude oversimplification of one part of the 5S program is “get the junk out.”
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| TI implemented a ‘5S’ program at its 300 mm fab in Dallas. |
The program includes seiri, or sorting, which involves throwing away or storing all the non-essential items that tend to clutter a fab. Seiton involves setting up a smooth workflow for workers, the equipment and supplies. Seiso, or shining, includes setting up regular cleaning routines. Seiketsu requires standardizing on work procedures so that workers know exactly what is expected of them. Shitsuke involves sustaining the efforts by regular reviews so that improvements can occur naturally.
James said results at DFAB since 2005 include cutting process yield losses in half, improving human productivity by 32%, and reducing tool maintenance costs by 58% and tool downtime by 47%. The product cycle time was reduced by 27%, and the cost per wafer was cut by 25%, he said.
Cutting variability is key
In an afternoon workshop by management consultant James Ignizio at the ISMI symposium, fab managers were told to focus on the role that good maintenance can play in improving cycle times. “The fixation on cost reduction involves a failure to comprehend the importance of fast cycle times,” said Ignizio, an author of nine books.
Although an automobile assembly line is synchronous, with tightly coupled workflows, a semiconductor fab is asynchronous in how wafers move from tool to tool, Ignazio said. Thus, keeping any unevenness in the fab — which he defined as variability — to a minimum is key to reducing cycle times. “Variability is one of the enemies of factory performance. Remember that a factory is a non-linear, dynamic, stochastic system with feedback,” he told a group of ~20 fab managers.
In his various consulting stints at chip fabs around the world, Ignizio said there are striking differences in maintenance procedures. Some U.S. companies don’t have a formal maintenance department, indicating the lack of clout that maintenance holds at those companies.
“Maintenance impacts cycle time and variability, which determines to a great degree the performance of the factory,” he said. The ratio between scheduled downtime for regular maintenance and unscheduled downtime is an important indicator, with a typical fab experiencing one-third of its downtime as unscheduled. “In some fabs, one-half is unscheduled downtime, and that is a tremendous opportunity to reduce variability.”
Adventa-Lam Research PM program
Rebecca Cooper, deputy director of manufacturing control systems at Adventa Control Technologies Inc. (ACT, Plano, Texas), and Chung-Ho Huang, vice president of software at Lam Research Corp. (Fremont, Calif.), described a predictive maintenance program.
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| Preventive and predictive maintenance are part of the Next Generation Factory program at ISMI. |
The Adventa-Lam project created a tool that automates a variety of maintenance processes, including a warning when a part needs replacement and parts inventories. The tool anticipated several of the maintenance automation recommendations in the 19 guidelines in the ISMI Next Generation Factory (NGF) program, Cooper said.
