Semiconductor manufacturers weigh 'dense pack' retrofitting
03/01/2004
By Ray House
Microchips are getting smaller and circuits more efficient at an amazingly rapid rate. But while chips are tinier than ever, the tools that handle their manufacture are getting larger. They can measure above eight feet high and can weigh more than 20,000 pounds.
At the same time, prominent Silicon Valley semiconductor companies are suffering financial setbacks. The sustained slide in profits has led to running some of the tightest manufacturing ships in microchip-making history. Ironically, while many of the tools are increasingly bigger in size, many companies are downsizing their work forces and workspaces.
Many of the large companies are not seeking to lease new space but instead are retrofitting existing spaces. They are hiring specialized design teams that can skillfully reconfigure spaces to be tighter and more efficient with a minimum of bare space. Ultimately, many are finding retrofitting/upgrading is more cost-effective than leasing new properties, though the practice is not without its drawbacks.
Frequently, chip manufacturers are maintaining a presence in the Valley, then shifting the bulk of their "fab" facilities to less-expensive real estate, sometimes just a few miles away, or to other regions here and abroad where rent is cheaper.
When they do choose to stay put, they may consolidate the work force into less space and sell or lease excess space. They may reconfigure office space into lab space or vice versa. In fact, some may end up with lab space that is half its former size, yet equipment that is heavier and larger than anything they've needed in the past. So, what are they doing to conform to such changes?
To accommodate equipment weighing 10-tons or more, most need to beef up their existing structures. This requires reinforcing the entire moving path a tool will travel, from loading dock to resting place. One Fortune 500 company's facility installed steel beams and girders to brace an existing second floor structure. In other areas, where installation of new beams was not practical, due to location of existing equipment, ductwork, piping, conduits, etc., the concrete floor was chopped out, to allow installation of welded studs on top of the existing beams to provide additional stiffening. The existing access floor above this sub floor was modified as well, with new struts and diagonal bracing along the identified tool move-in path.
Due to the height and width clearances required and increasing weights of larger tools, planners often need to raise ceilings, widen door openings and/or use tools that break down and can be reassembled in the place they will be used.
It is not always possible to increase a building's tool move in path. In the same project noted earlier, a temporary exterior lift was installed to gain access to the second level of the fab, where the tool was to be placed. The building's exterior skin and loading dock was modified as well to allow move-in.
Effective design
Often, a facility can gain space by examining and reducing circulation paths and placing tools and personnel in a minimal area. One of the challenges to this type of "dense pack" planning is providing required employee amenities, as well as placing all tools and equipment with required operational clearances. As tools are shuffled, original circulation paths and even exit corridors can be reconfigured to a minimum, or can be eliminated completely, provided an alternative egress plan can be implemented (as approved by the local building and fire department). To conduct proper maintenance, an access space surrounding a piece of equipment is typically required.
It's essential to provide a flexible infrastructure that allows for changing utility needs in functional areas. Items include process and building utilities, support equipment locations (rooftops, service pads) and general and scrubbed exhaust.
When reviewing budget and schedule impacts regarding dense packing tools and equipment, be aware that squeezing more machinery and open chemicals into a smaller area may precipitate a change in the occupancy definition of a space. For example, space that was once a B (office) or F1 (fabrication) occupancy may become an H (hazardous) occupancy due to the increased amount of chemicals/gasses within a control area. Building construction requirements are more restrictive in an H occupancy (i.e., increased fire/ life safety requirements, number of exits and exit devices, fire-rated assemblies, construction materials, structure, etc.).
How to plan
It may sound obvious, but the key to an efficient, cost-effective operation is a detailed, long-term plan for the facility, which provides adequate access to all fab and support areas, as well as an infrastructure that can accommodate expansion, reduction and other changes with regard to the functional areas of the building equipment move-in path. Reconfiguring of space at even the largest and most sophisticated semiconductor facilities is typical due to technology, economy, and market changes.
To achieve the most cost-effective design, therefore, a team must strike a fine balance between programming for adequate space and avoiding over-programming. Since it is not cost-effective to retrofit a space each time a new piece of equipment is added,. a good planner will aid the client in identifying future needs (to the extent possible), and how to design for flexibility. To maintain the company's quarterly earnings, the space must accommodate future needs but should not be constructed over and above anticipated future needs.
Drawbacks to retrofitting
At first glance, it may seem that dense packing a fab space will cut costs, yet it also has repercussions. Support equipment on the roof or in the service yard may need to be upgraded, or a larger service yard could be required to accommodate more or larger equipment. Also, condensing more equipment (and subsequently chemicals) into a tighter space could require the area of improvement to become an H occupancy which may, in turn, raise the cost of building upgrades and operation.
Increased support equipment could be relegated to an already tight-fitting service yard, and, especially in a clean environment, additional rooftop units could precipitate strengthening the roof to accommodate increased structural loads.
With more heat typically generated by the dense-packing addition and by adding new tools and equipment, adding increased cooling capacity becomes necessary.
In reality, many fabrication facilities do not have a large enough expansion space to augment the huge tools that are becoming more commonplace. Management must analyze every inch of space when deciding what should remain and what can be eliminated. The cost to buy or lease a new space vs. the expense of a retrofit must be evaluated before making a decision.
Many intricacies dictate the type of plan that is best for an individual company. This determination can be made only after an extensive evaluation is completed, which takes into consideration the full scope of the project—including a detailed budget and a schedule. This report may be used as a tool to evaluate costs and to raise capital for the project. Commissioning such a report is crucial to any company wishing to set a proper course for its business.
Keeping these factors in mind when expanding or retrofitting a semiconductor facility will contribute to running a tight ship.
RAY HOUSE is a project manager, based in Mountain View, Calif. for HDR Inc.—an architectural, engineering, planning and consulting firm.