Special Report

Advanced microelectronics industries thrive in Twin Cities region

Tom Cheyney

Although it's sometimes overlooked as a semiconductor and advanced microelectronics hub, the Minneapolis/St. Paul area is home to a significant concentration of manufacturers, suppliers, and research institutions. Seagate, 3M, Honeywell, Medtronics, Cypress Semiconductor, VTC, FSI International, and Fluoroware are some of the companies either based in the region or with major facilities there, while the University of Minnesota is a world-class microtechnology research center. An annual tally of the revenues generated by the companies' facilities in the region totals billions of dollars, while graduates of the university have landed jobs with leading semiconductor and disk-drive companies around the world.

When I toured the area in May, the long Minnesota winter had finally ended. The arrival of spring signaled a time of new growth in the local microelectronics industry. The facilities I visited were either adding on new space or renovating existing space. Cypress was bringing in the last process tools to its new Fab IV-A and was fitting out Fab IV-B. VTC was putting the finishing touches on its new 40,000-sq-ft addition, with plans to break ground on a $100-million building in 1998. FSI's state-of-the-art Class 1 process lab was nearing completion, while across the street Fluoroware was gearing up to add an impressive multilayer blow molding unit for high-purity chemical containers. Physical Electronics (PHI) was keeping up with a surge in orders for its advanced analytical metrology tools. The old engineering building at the University of Minnesota was scheduled to be demolished within the year and a $22-million one built in its place.

Historical links connect the corporate lineages of several of these organizations. Control Data played a role in both VTC's and Cypress's respective legacies. VTC was originally the bipolar division of Control Data, bought for $10.6 million by current CEO Larry Jodsaas and partner Greg Peterson. Cypress purchased what is now its Fab III building from Control Data in 1991 for a song (about $15 million) and has turned the campus into one of the company's main breadwinners. FSI and Fluoroware are more than just business park neighbors in Chaska, they share a common ancestry: FSI was spun off from Fluoroware in 1973. PHI's founders were either professors or alumni of the University of Minnesota, and some of its technologies were developed at the school's labs.

Cypress, VTC Blossom in Bloomington

Space is at a premium at Cypress's Bloomington fabs, with tool density a driving force in the kinds of creative design solutions implemented or planned there, says Mark Vilchuck, site facilities manager. Office areas are being changed into cleanrooms, and subfab space is metamorphosing into regular fab space. As many other fabs have done, the company decided to isolate its new CMP area, creating a fab within a fab with its own change room and air supply. As many as 40 tools will eventually be installed, notes Vilchuck. He describes a "mezzanine approach" to isolating Fab IV's new lithography tools and deep UV tunnel.

Taken together, Fabs III and IV and the separate CMP area take up some 52,000 sq ft, with a total of 111,000, including subfab areas, under HEPA-filtered air. One of the unusual aspects of these fabs is the use of minienvironments on a large scale. Vilchuck estimates that the older facility is "about 85% SMIF'ed," with more than 90% of the new Fab IV areas using isolation technology.

One of the reasons for Cypress's space limitations is not something one usually finds in an engineering manual. A look through the windows of the company lunchroom reveals seven unusually large lumps in the earth outside, which are Ojibwa burial mounds protected by law from desecration. Vilchuck says when the company rededicated the plant, it brought in shamans from the tribe to reconsecrate the ground.

One interesting statistic pointed out by Vilchuck is a comparison of airflows at Cypress's facilities and the amount used at the nearby Mall of America. Cypress circulates about 3.5 million cu ft/min versus 3 million for the consumer mecca. Makeup air and the task of keeping humidity stable are challenges, says Vilchuck, because of the rapid shifts in outside air temperature that the region is prone to. Since Minnesota also has to deal with an inordinate number of thunderstorms--the state ranks number three in the United States for lightning ground strikes, he notes--Cypress has three different utility power feeds with uninterruptible switchover backing up the critical loads in case of a hit on the electrical grids.

Cypress organizes its teams by process, Vilchuck says, with a major initiative on defect reduction. "I'd have to say we're somewhat outside of the norm, especially this facility. We've reinvented layouts, changed our tool sets numerous times, and the denser the tool sets get, the harder it is. . . . It's a challenge for the guys upstairs to not only keep the equipment running but also to stay ahead of the defect group. They've made some real good strides in the last few months."

VTC's fab is a few minutes away from the Cypress campus, and a generation or two away in terms of the processes being run. The market leader in supplying ICs to the data storage industry started production of 0.7-µm processes earlier this year, with plans for 0.5µm by early 1998, according to process engineering manager Hamid Berenjian. In the older part of the fab, the company still runs 1.25-µm processes.

Berenjian notes that VTC does not use in situ particle monitors. "We do a daily check of particles on all of our equipment; basically, they process the wafer through the machine and . . . do a surface scan and read the particles and every machine in the fab is spec'ed. So every machine in the fab gets checked daily at least, with the exception of the epi reactors. With them, after so many shots, every shot is monitored." VTC has purchased a KLA-Tencor 7700 AIT tool to help detect repeating defects that have not been picked up until the end of the line. Particle and moisture levels in the gas and chemical lines are also checked continuously.

Both VTC and Cypress are turning out chips 24 hours a day, 7 days a week, with three shifts covering the workload at VTC and four at Cypress. This kind of manufacturing pressure creates a demand for high-quality operators and technicians. "The big problem we're having now that lead times on tools have come back to reasonable levels," notes Vilchuck, "is getting the bodies." Both companies have well-developed training programs for new hires. Videos on cleanroom protocol, safety, and the like are shown during orientation, then the trainees are taken through the gowning process and into the fab.

Once they are there, Cypress assigns dedicated trainers to the new employees. Peggy Pasillas, the company's training manager, explains. "Once they've gone through orientation, they're assigned to a trainer for four weeks. The trainer will continually reinforce what the cleanroom protocol is, making sure that they're gowned properly every day. Every time they come in and go out of the fab, they're with the trainer, so there's somebody to verify that they're doing it correctly. . . . Our focus has been on hands-on training, getting people to know how to run their equipment and know what to look for in the specific process they'll be running. That seems to work pretty well."

VTC's manufacturing systems manager Patrice Nordstrom explains the slightly different method used at her company. "We don't have dedicated trainers. We have a certain group of operators that we tend to use but anybody who's been at a job for a certain length of time is qualified as a trainer. It's up to the supervisors whom they choose." VTC starts new hires on third shift, typically for six weeks or so, with the rookies and their trainers always together. After the new hires get their engineering audit they're allowed to operate on their own, says Nordstrom.

Pasillas, who began as an operator in Sperry's old 3-in. fab, has also done many wafer-handling studies in conjunction with the defect reduction engineers at Cypress. "We did some data analysis and some test lots, looking at the yields, seeing where we could change our handling procedures to reduce particles. In Fab IV, because it's much more automated, we don't have as much human involvement so it's a little less of an issue, so we make sure people are following all the standard protocols and see how they recover from errors, things like that." In a recent effort to expand the homegrown workforce, Cypress, VTC, and other local companies began cooperating with Normandale Community College to develop a two- year vacuum technology program, including a wafer-fab laboratory at the junior college.

Fluoroware, FSI Flourish in Chaska

Ultraclean processing and machine-shop plastic molding coexist side by side at Fluoroware, and both aspects of the company's manufacturing are highly computerized and automated. Hundreds of thousands of square feet of testing, manufacturing, and assembly floor space is used to produce the end products, be they chemical containers, valves, wafer carriers, or other items. The company is the largest converter of Teflon PFA in the world, according to John Goodman, vice president of engineering, who adds that 90% of all IC devices ever made have been touched by a Fluoroware product.

One of Goodman's favorite tools is an advanced, 3-D rapid prototyping tool. "We can literally have a design meeting with people one day and, depending on the run time for the machine, a day or two later we can sit down at the table with the finished part and take a look at it. We take the 3-D model and the computer slices planes of whatever thicknesses we want to use, and this thing"--pointing at the system--"has a little extrusion head up in here. It draws one plane at a time; we can make the most intricate shapes." This design testing ability came in handy during SEMI's early discussions of 300-mm carriers, where Fluoroware showed prototypes that the committee members could evaluate, saving the company a lot of time and energy on the tooling front as well.

The technical research group at Fluoroware has a well-equipped analytical lab at its disposal, where the team can perform inspection and control of incoming raw materials and other tasks. The lab includes a Class 1 cleanroom, in which, says Goodman, "we have the capability to do all kinds of particulate or organic microcontamination research." One of the current projects couples high-end contamination control specs with the level of flame retardancy now demanded by insurance carriers. "We're developing materials that will not contaminate the wafers and that will continue to protect them like they do today but will also meet the flame retardancy and fire safety codes the insurance companies like," explains Goodman.

As Goodman notes, their customers expect ultraclean and reliable products. "Productivity is absolutely what our customers are on us for. Cleanliness is kind of a given now, you have to be at a certain level, but you better make the customers more productive. That's what our emphasis is: raising our mean time between failures and making the product more reliable. Wanting to have bigger distribution systems, getting more flow through the same size package, things like that." This move to greater productivity is at the heart of Fluoroware's current strategies, especially in light of the ramp-up to 300 mm.

FSI's facility was "built strategically. . . we intended it to have extra capacity the day we moved in," says the company's executive vice president of operations, J. Wayne Stewart. "Our objective throughout the last several years has been to be in a position to respond to our customers. We want to be ahead of the market in terms of capability, viewpoint, processes, and capacities." As he watches technicians working on an Aries cleaning tool within an enclosed Class 10 space on the manufacturing floor, Stewart notes that "cleanliness begins with customer requirements. This facility was designed with [the potential for] a very easy upgrade of an order-of-magnitude cleanliness," with ULPA filtration in place throughout the space.

Because all tests on the production floor are performed with DI water during manufacturing of FSI's surface conditioning and chemical distribution equipment and even more water is required for its new process lab, the company has had to triple the capacity of its DI-water plant and come up with ways to improve reuse. "We use so much water that we have to reclaim it once it goes through the tools, or this would be prohibitively expensive," explains Cam Williams, manager of the facilities and environmental services department. "We have both a distribution system where we clean up the water, to get it to the specs that are needed, and a reclaim system. We're reclaiming about 95% of the water that we use on the production floor," in some cases making it cleaner than it was before. Analytical tools routinely monitor TOC, temperature, pH, particles, and the like throughout the system, with the technical staff often performing correlations of the different parameters, says Williams. As for the disposal of chemicals used in the facility, all of them flow through a three-tank pretreatment setup before being discharged under permit into the sewer system, she notes.

Known for its technical staff's ability to work with customers and the research community formally and informally, FSI actively pursues applications and development in the surface conditioning and chemical management areas. Dan Syverson, marketing manager in the surface conditioning division, says the company is working on a three-year plan to develop a "common platform approach" for its Excalibur and Aries cleaning systems, with modules for each tool and process coexisting in one cluster. He says the first prototype is scheduled for completion in late 1998.

When asked about the imminent 300-mm and 0.18-µm eras, Don Deal, process technology manager, foresees various possibilities in the surface cleaning equipment industry, depending on the process: batch systems with wet and vapor capabilities, and single-wafer systems with wet and vapor cleaning options as well. Both managers agree that getting key customers to provide input "right up front" during the design and development phases has become essential during the creation of next generation tools. FSI also sends process engineers out into the field to "improve processes and equipment, develop new modules for the equipment," where, as Deal notes, "we are living with our customer and the rest of the equipment."

A test bed for the evaluation and quantification of different types of chemical-delivery systems, which FSI claims to be an industry first, has been set up in the company's lab. "One of the problems with an existing installation," explains Todd Myers of the chemical management division (CMD), "is when you try to put in different filters, different technologies, you're messing with a fab that's manufacturing, and the customers are not going to let you do that. It's also difficult to get side-by-side, real comparisons with the same chemicals, same purity, same conditions. To find a cause-and-effect relationship, you really need to do it in the lab."

The kind of information such a lab provides is crucial as chip linewidths plummet. "One of the points we make is that when you get down to 0.13µm and below," says John Delebo, CMD sales and marketing manager, "what's going to happen on the wet chemical side is dependent on the process. For the ultracritical clean chemicals that we produce in gas-chemical generation, where we're taking an electronics-grade gas and blending it with fab DI water with parts-per-trillion levels of water and gas and less than parts per trillion in metals and particles, then putting a small gas-chemical generator underneath the tool, with very short distribution tubing length, and voila, you have your very, very ultrapure chemical for the etch-and-clean process. I think the ultimate goal is to have wet chemical etch-rate control at the tool."

PHI Likes Moore's Law

"Each design-rule step will increase the applications of our technologies," notes Marlin Braun, semiconductor fab business manager of Eden Prairie­based PHI. "We view that we're really at the beginning of our semiconductor fab support market." The company, recently purchased by High Voltage Engineering Corp. of Boston, supplies ultra-high-vacuum, precision optics analytical tools for a variety of industries. Some 85% of its products' contents are made at the Twin Cities facility, says Braun. One of the company's instruments for the microchip market is the Smart-200 microanalysis review tool, which combines scanning electron microscopy and Auger emission spectroscopy capabilities.

"We're focused more on the submicron and sub-half-micron particles, so we tend to zero in on those during the demonstrations in the applications lab," says Stephen Clough, company director. A recent study done with a customer found a defect picked up by a KLA-Tencor tool that turned out to be a 500­600-Åpiece of photoresist residue. "We got a clear Auger signature for both the carbon and the sulfur in the photoresist. We could quickly obtain a survey of it and actually get unattended images of it overnight. We're really pushing the small-particle capabilities of the tool," Clough adds. He credits Sematech's lab managers working group for a lot of the impetus to develop the tool in the first place.

Gophers' Particle Lab Prospers

The University of Minnesota's Particle Technology Lab is one of the leading centers for research on the measurement and behavior of gasborne particles or aerosols. Benjamin Liu, director of the lab, says the research program includes cleanroom and microcontamination control, filtration, and air quality and air pollution studies as well as basic aerosol research and instrumentation. Access to the university's supercomputers allows students and faculty to run complex simulations of particle behavior and the like as well as perform advanced data analysis, the Regents' professor notes.

One new tool developed by Peter McMurry, one of Liu's fellow professors, shows promise for advanced microelectronics applications. "It's a PBMS, or particle beam mass spectrometer," explains Liu. "It allows you to sample particles from the vacuum system of a CVD machine and then eject them through an aerosol lens to form a beam of particles, and these particles can be as small as a few nanometers in size. They're injected into the vacuum system . . . and we can detect not only the size of the particle, but the electrical charge. The detection limit of the instrument is from about 3­5 nm to about 30 nm. It's the only instrument around that can detect particles of that size in vacuum systems." With a third-generation prototype in place at the lab, units for Sandia National Labs and an unnamed company are also being built. "The PBMS is getting pretty close to the commercialization phase," says Liu.

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