Memory disk plant goes from concept to production in 7 months
HMT Technology builds two new facilities to keep disk drive manufacturers supplied with top-quality, low-cost memory disks.
By Sheila Galatowitsch
To meet the demand for computer memory disks — the heart of a disk drive — HMT Technology in a record seven months designed, constructed and brought online a 124,000-square-foot facility at its Fremont, CA, headquarters. The company`s production in the past few years has gone from half a million disks per month to four million disks per month, and the new $87 million site will allow HMT to double its capacity.
The enormous demand for more storage capacity and higher quality thin film disks, driven by memory-intensive software applications such as Windows 95 and Windows NT, multimedia and digital imaging, has prompted HMT to make ongoing investments in capital equipment, facilities and employees to meet its customers` needs, says George Berberis, HMT`s director of manufacturing.
Whereas 500- to 600-Mbyte disks were adequate in the recent past, today`s computers require 2- to 3-Gbytes of memory. In this business environment, it was necessary for HMT to take swift action to meet demand on the high-end market.
“We felt now was the time to capitalize on the industry with high-end, high-quality products and establish our leadership in technology and cost,” Berberis says. “The demand was there, driven by customers looking for a high-end product that wasn`t available at the time. There was no time for lengthy studies or reengineering. It was simply a matter of building factory capacity to meet the demand.”
The company was able to cut nearly a year from the project by working closely with its prime contractor, ICOM Mechanical Inc. (San Jose, CA). HMT and ICOM have been working together for more than 10 years on various cleanroom projects and both are ISO-certified. The new Fremont building, which includes a 60,000-square-foot cleanroom, augments another new facility in Eugene, OR, constructed by ICOM in 1996.
In both cases, ICOM played a key role in helping to design the final layout and make on-site decisions to meet the schedule, Berberis says. ICOM made “thousands of decisions on the fly with the full trust and cooperation from HMT,” he says.
The 105,000-square-foot building in Eugene handles raw material, plating and polishing operations, while the Fremont site conducts texturing through certification of the memory disks. Combined, the two sites cover the entire manufacturing process from beginning to end, with some plating and polishing operations duplicated.
Work on the Fremont project began in July 1996. By January 1997, all the Phase I equipment was installed and qualified, and the facility was online, more than doubling the company`s production capability.
The largest part of the facility is a 60,000-square-foot cleanroom, which features 40,000 square feet of Class 10 space and 20,000 square feet of Class 1,000 space. Four modular cleanroom bays are configured to perform the same process sequence. Each bay measures 15,000 square feet, combining 10,000 square feet of Class 10 space with 5,000 square feet of Class 1,000. The bays share the same facilities.
The process advances from texturing (the first step) to washing and laser texturing (the second step), then to sputtering, lubing and buffing. Each disk is then fully tested for electrical parameters and head fly-ability, which is a “glide” test where the glide head flies over the disk surface at approximately one microinch.
The texturing is performed in the Class 1,000 area and the remaining processes in Class 10. The certified disks are bagged in a 3,000-square-foot, Class 10 bag-in area, then shipped to disk drive manufacturers worldwide. HUNTAIR (Tigard, OR) supplied the cleanroom modules used throughout both the Fremont and Eugene sites.
Stringent cleanliness is key to an operation that requires the certification heads to fly at one-millionth-of-an-inch over spinning disks. Berberis likens the process to “flying a 747 one foot over the ground, hoping you will not crash. Any asperity on the disk can render the drive inoperable.” The industry is headed toward even lower flying heights, Berberis says, to about 0.8 millionths of an inch. With the new facility in place, HMT will be able to respond on time to its customers` increasingly demanding expec tations, he says.
Extreme cleanliness is most critical between the washing and sputtering operations. “Once the product is sputtered, you are done,” Berberis says. “Any damage on the substrate before sputtering will stay with it and you can`t recover it.” Losses due to contamination are unacceptable in an industry that relies on high yields for profitability. “The reason we are going so clean is to capitalize on these yields. We cannot be the low-cost producer if we have low yields.”
According to Berberis, the Fremont facility incorporates the latest in cleanroom technology. The facility has full ULPA filtration coverage and automatic temperature and humidity controls with humidity at 45 percent ۬ percent and temperature at 68 degrees ۪.5 degree Fahrenheit. Particle counts are monitored continuously; the HUNTAIR modules recirculate air throughout the cleanroom; and anti-static bars cover the entire cleanroom ceiling.
“On the process side, we took a three-prong approach to the contamination problem,” Berberis explains. “We designed the cleanroom floor with a focus on improving product flow, redesigning process equipment and investing in automation and MIS [manufacturing information systems].”
By simplifying the product flow, HMT was able to reduce the total process cycle time, thus reducing the time the product is exposed to the environment. The approach also helped keep product inventories to a minimum, he adds. “There is not much work-in-progress product in the line to obstruct air flows. The floor is clean and orderly and uncluttered,” he says. The four distinct bays help facilitate the product flow, which flows in one direction only. Each bay can produce a different product family.
By redesigning and appropriately positioning the process equipment on the cleanroom floor, HMT was able to reduce contamination introduced into the cleanroom by equipment. “We did things like vacuum out moving cylinders, vacuum debris from the buffing operation, position the bulk of the equipment out of the cleanroom, and leave a small opening for the product to get into and out of the machine,” he says.
“By automating, we have reduced the number of people in the cleanroom — the major source of uncontrolled contamination — by as much as 50 percent. Automation and MIS afforded us to go to a paperless factory, thus removing another source of contamination. All product is tracked through radio frequency identification read/write tags to which data is written and read from. All process control charts are on-line and can be accessed by operators and engineers alike from any place within the company or from home through a modem connection.”
Berberis says that HMT also pays close attention to employee training. New employees are cleanroom trained and certified before they enter the cleanroom and re-certified annually. The company`s quality assurance department monitors employee behavior within the cleanroom and issues corrective action requests if necessary.
Concrete slab construction
One of the biggest challenges for the contractor was construction of a two-foot thick, 94,000-square-foot concrete slab while the facility was still being designed, according to Dan Littleton, vice president of engineering at ICOM. The concrete slab “allowed us to do a minimal amount of excavation on-site,” he says. “It saved three weeks on the project schedule to go with a mat slab as opposed to other types of foundations. It also allowed us to overcome a shallow water table and highly expansive soil condition problems that were on the site.”
The slab will also give the facility a high degree of structural integrity so that HMT will have the flexibility to relocate equipment, and expand or modify the cleanroom with no major structural constraints. A three-foot-high modular cleanroom access floor was built on top of the slab. The floor is perforated in the cleanroom and grated in the service chases.
The concrete pour for the slab was the single largest pour in Fremont history, Littleton says: 9,000 cubic yards of concrete in one single pour over a 14-hour time period. “There was a steady line of trucks and three concrete batch plants on-line to do the work, and three concrete delivery companies,” he says. “For 14 hours, trucks were showing up every four and a half minutes.”
Littleton credits the City of Fremont for granting permits for pieces of the project, including the concrete slab, while the building design was still underway. “It`s unusual to get that level of cooperation,” he says. Part of the complications were due to an existing water line that was ultimately relocated. “We built two-thirds of the mat slab first while getting the easement scheduled to be relocated. We continued construction instead of waiting for final approval of relocation of the easement.”
Other problems also threatened the fast-track construction. When a rainy period ensued before the roof was erected, ICOM`s design team quickly designed and installed a temporary roof to beat the weather. Meeting the stringent one-hour wall and roof fireproofing specification also proved difficult because the construction was not performed in a logical sequence, Littleton says. “We were putting sheet rock on building columns and the underside of the roof while we were installing process piping and cleanroom modules,” he explains. “We had an exceptional amount of out-of-sequence work. We were installing cleanroom modules while we still didn`t have outside walls on the building.”
ICOM minimized the confusing construction activities by creative problem- solving. For example, to avoid spending time removing it, the temporary roof was ultimately incorporated into the final roof design. Instead of placing insulation underneath the permanent roof, ICOM sandwiched it between the temporary and permanent roofing. “That allowed us to begin to do the sheet rock sooner to get to the one-hour rating. It also allowed that part of the project to go faster and minimized the damage we would have had installing the insulation in the rain,” Littleton says.
Off-site prefabrication of many of the construction elements also helped to meet the schedule. The secondary structural steel systems for the cleanroom modules, the process piping assembles, the mechanical hydronic systems and the cleanroom modules themselves were designed and built off-site, then brought in and erected in place. The prefabrication was done at the same time as the building and roof construction.
The facility features several miles of pipe installed in a short period of time, Littleton says. It also has 2,500 kVA emergency generator power for the process systems, three different types of chilled water, process cooling water, two vacuum systems, process and condensate drains, a hot water boiler system, nitrogen, clean-dry air and argon. ICOM performed all the process piping installation, as well as the equipment installation, rigging, attachment and seismic installation.
The first three bays are now operating at close to full automation. The fourth bay will be operational by June. “Once all four bays are complete, it will basically be one wide open cleanroom — 60,000 square feet all in common,” Littleton says.
The raw material operation
In Eugene, ICOM built a 105,000-square-foot facility around an existing 40,000-square-foot aluminum substrate factory. The existing building was cut in half, with cleanroom operations continuing on one side, while demolition and construction were performed on the other side. Office personnel were temporarily housed in trailers set up on the parking lot during the construction. When the first half of the facility was completed, the cleanroom operations were moved and construction began on the second half.
The $40 million structure has a 10,000-square-foot cleanroom to accommodate full-scale automatic disk plating and polishing. The cleanroom includes 2,000 square feet of Class 100 space and 8,000 square feet of Class 10,000 space. “The cleanrooms are basically for plating operations,” Littleton says. The automatic plating line is within the Class 100 space; the support area surrounding it is Class 10,000. An additional 2,000 square feet of Class 1,000 space handles incoming product and inspection. Temperature is controlled at 68 degrees ۫ degree Fahrenheit.
One critical design element for the Eugene operation is that the velocity on the ULPA filtration had to match the scrub exhaust volume on the automatic plating line. “We needed to maintain a clean environment within the plating line chamber, so we had to balance the flows perfectly between the clean airflow and exhaust,” Littleton says.
The chemicals used in Eugene made the process piping design challenging and called for a sophisticated acid waste neutralization system. “There are 15 different types of drain lines from the automatic plating line,” Littleton says. “All of them had to be treated differently in the waste neutralization process.”
The plant was the first automatic nickel plating system in Eugene, so obtaining permits was tricky, Littleton says. “It took about five months to get through permitting and four months to build.” Completed in December 1996, ICOM added a second plating line last month and is in the process of expanding office and lab areas.
On both the Fremont and Eugene projects, hundreds of personnel worked around the clock to meet the schedules. The Santa Clara-based general contractor for the Fremont project, E. A. Hathaway and Co., and the Eugene general contractor, Hyland Construction, deserve credit for coordinating the on-site personnel and helping to meet the schedule, according to Littleton.
Although designed for Class 10 requirements, HMT`s Fremont facility has been certified as a Class 1 cleanroom, setting it clearly above the industry standard, Littleton says. “We believe these facilities are ahead of the curve and will easily accommodate future needs.”
Construction at the HMT site included installation of a 94,000-square-foot slab, on which a three-foot-high modular cleanroom access floor was built. (Photo Copyright 1997 Upshots.)
This photo shows the area in the service chase that supports the sputtering process, which is performed in a Class 10 area.
This photo depicts an MD 08 in the texture area of the support cleanroom. The texturing is performed in a Class 1,000 area.