Publications

It Takes a Team to Make it Clean

by Jeff Schantz

May 17, 2017

Many of the cleanrooms for nanofabrication, bioengineering and tissue processing are among the most technically complex and costly core facilities to build. Whether you're researching compound semiconductors or nanofabrication for commercial devices, or trying to develop new therapies through biomedical discovery, creating high-performance validated environments is a challenge. We're all fascinated by the "gee-whiz" factor and pace of innovation that occurs in cleanrooms. We’ve enjoyed helping academic researchers, government agencies, and industry alike find creative ways to accelerate project delivery schedules and drive down the expense of these project types. Regardless of size or complexity, cleanrooms require a team approach. We collaborate with our clients and professional partners when creating these unique, special environments.

Designing, engineering, and constructing these environments is truly a collective effort. At EYP, we take a "best of breed" approach, engaging with industry-leading experts, each with a keen understanding of how building systems affect overall performance. Our knowledge and experience – integrating mechanical, electrical, plumbing, fire protection, structural, civil, geotechnical, vibration, electromagnetic interference (EMI), cleanroom systems, hazardous materials and safety specialists – will provide a value to your project's success.

Cleanrooms for Research

Many of the cleanroom projects we’ve contributed to have been focused on compound semiconductor development for prototyping, materials science, molecular engineering, and instrument development. Research-grade facilities tend to offer a specific, targeted microcosm of fabrication capabilities with the goal of producing prototypes of new devices. Often the goal is to produce one or a few, not millions, of copies, as in a production cleanroom. The types of processes might include support for:

  • Etching
  • Deposition
  • Lithography
  • MBE
  • Thin Film
  • E-Beam
  • Steppers
  • Chemistry
  • Instrument Development
  • Metrology
  • Imaging
  • Prototyping and Assembly
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Computer Chip Commercialization Center, fan filter units for air filtration and positive pressure

Building-as-Instrument

Over the years, we’ve witnessed advances in nanotechnology, molecular engineering and bioengineering. These changes have driven the need for the highest-performing environments for imaging equipment. Many national laboratories have buildings where the building itself is considered part of the instrument. This is more typical where the research involves tool-making; for which the highest-performing operating environments are critical to getting the best results. This model is exemplified by our experience with designing to support the latest generation of STEM/AFM/Optical technologies including aberration/chromatic/spherically corrected STEMs; dual photon optical microscopy; and adaptive AFM devices for surface characterization of organic and inorganic materials. In partnership with our electromagnetic interference (EMI) and vibration consultants, we have engineered facilities that outperform NIST-A vibration requirements, with EMF/RFI performance below .5 Mg, and temperature, thermal performance with >.1% temperature variation and acoustic performance >20 Db. Frequently, when assessing existing facilities for performance, we conduct an ambient conditions analysis to set an engineering baseline. This data is used to analyze site data and identify any site adjacencies or challenges that could impact the precision of fabrication equipment or characterization instrumentation.

Floor Capacity and Performance

We all know how important the right foundation is to any high-performance project under construction. A high-capacity floor slab that is very flat is crucial in compound semiconductor facilities. Some operations and optical calibrations require great precision, making flatness critical. For example, a 10-ton capacity at the floor – whether raised or slab on grade – requires engineering in a safety factor. In slab-on-grade construction, it is essential to properly prepare the application of a static-free, high-durability epoxy floor. This process requires a fully cured slab that can be properly prepared through mechanical abrasion, acid wash, and final cleaning prior to application of the final epoxy surface. The flatter the concrete slab, the better the application of the epoxy floor. Early onboarding of the Construction Manager is critical for this and many other reasons. If a raised slab is used, the precision of concrete placement for overall vibration performance can be achieved with waffle slabs that offer frequent slab openings for floor penetrations, allowing easy routing of utilities between fabrication level and sub-fab areas. Bringing your CM partner in early in planning and design can help ensure the necessary level of slab precision is specified and executed.

The design of the floor slab must also consider the inclusion of isolation slabs for shakers, cryogenic chambers, EMI testing chambers and other critical test-bed systems. In raised-floor systems designed for laminar flow, the floor-loading arrangement will affect the overall design of the slab below. Typically, these systems create the return-air plenum at the floor to provide laminar flow over most of the space. This system allows for greater flexibility in the layout and positioning of equipment within the space, making the high bay more adaptable to mission requirements.

Cleanroom Configuration

Knowledgeable MEP partners are invaluable to the success of cleanroom projects. To achieve optimal results, cleanroom systems for rapid prototyping and high-bay facilities must meet certain configuration requirements. For example, since the location of the supply and return air diffusers, as well as the diffuser type, is critical to systems performance, locating supply air registers high and their returns low will create a laminar flow, but not over large areas. A raised floor with a return-air plenum provides better performance in a ballroom configuration, because most activity will likely take place in the center of the room. Proper location of filter banks in relation to air handlers also impacts cleanroom performance and operation: “staging” the sequence of clean to cleanest can help ensure protocols. For instance, if a high-bay space is operating at Class 100, the loading dock might operate at Class 100 and higher, while sub-assembly spaces, prototyping, test labs, and optical labs adjacent to the high bay would be at 10,000, 1,000, or even 100 with certain equipment. Such a staged approach is economical and operationally viable. A gowning sequence that goes through the sub-assembly and test labs before entering the high bay allows staff to enter into different levels of cleanliness by passing through separate airlocks. The difference between levels is reflected in the level of PPE worn.

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Brookhaven National Laboratory, photo credit: Rebecca Coles

Hazardous Process Materials

Safety and hazardous materials handling and disposal are also a necessary consideration in programming and planning workflows for cleanroom environments. Cleanroom processes, especially related to compound semiconductors and materials science, frequently involve hazardous chemicals and other materials. A complete and thorough gas and chemical analysis – involving user input from the cleanroom technicians and researchers, as well as process recommendations from tool vendors – is crucial to the success of the ultimate design. Equipment and tools can require that hazardous gas be piped in, waste then piped out and treated. In addition, acid neutralization, a standard procedural need, and flammable/corrosive exhaust must be made safe. Depending on the program, cleanrooms can further require hazardous gas monitoring and control system design and specification, which involves both sensing capabilities and a plan for response to hazardous situations. EYP’s partners for toxic gas monitoring perform gas and chemical usage analysis and provide trusted design and consulting services on critical support systems for facilities using hazardous process materials.

Our in-house Fire Protection and Life Safety Specialists review codes for project and industry safety standards and utilize best practices such as SEMI and FM Global Guidelines. Our consultants also help craft operational policies and procedures – including process and procedure specifications for handling, use, storage, processing and reclaim/abatement of hazardous process materials – for high-technology industrial and university laboratories and cleanrooms.

Temperature, Humidity and Airflow Stability

Maintaining narrow ranges of temperature and humidity is critical in assembly areas. Some components, especially composite materials, can be sensitive to environmental changes. The design of clean and stable air systems is required for both assembly and testing. In the sub-assembly areas, tolerances may be tighter, so the system design needs to offer flexibility and diversity. The best way to do this is to design capacity (CFM and BTU) and flexibility (controls and components) into the primary plant components. Having enough diversity is a key component to creating versatility. In configurations with multiple high bays, it is useful for each area to have its own AHU and exhaust systems. This separation provides redundancy and reliability in the operation and control of each space and also makes the facility easier to validate, as the operation of one side will not impact the operation of the other side.

Vibration, EMI and RFI Performance

We can’t overstate the importance of vibration, EMI and Radiofrequency Interference (RFI) in cleanroom facilities. Interestingly, vibration performance requirements will likely vary in different parts of a given facility depending on the research being conducted and the equipment in use. It is likely that performance might range from VC-A (100 microns/sec) to NIST-A (>3 microns/sec) or lower to accommodate optical, imaging, or test equipment. The use of shakers, mechanical equipment, or certain tools may require isolation slabs. Minimizing (or avoiding) EMI is critical both for testing and validation purposes and to the design and “cleanliness” of electrical power systems, IT Infrastructure, test bed equipment (Helmholz Chambers) and most important, security systems to meet classified DoD or SCIF requirements. If required, power may need to be conditioned with motor control centers that are either shielded or isolated from the test bed areas to avoid interference. RFI performance is equally important to maintaining a secure environment. Depending on schedule and budget, using Faraday cages around sensitive equipment is a common, less expensive, solution than whole-facility shielding.

Laboratories, Sub-assembly, Prototyping and Testing Areas

Workflow adjacencies and support spaces are also important considerations in holistic cleanroom facility design. Immediately adjacent to the cleanroom areas, there may be related (typically clean) areas, perhaps including high bays, where components can be assembled, tested and integrated. Test functions may include performance validation of certain components under stress conditions, such as extreme cold, high vacuum, or EMI and RFI stability. Testing facilities must be clean and flexible, with stringent levels of vibration performance, temperature, and humidity stability; many include smaller crane rails designed to move sub-components or aid with sub-assemblies. To achieve a high degree of flexibility, we often see sub-assembly facilities designed to accommodate a variety of functions, from optical testing to assembly. The basic concept involves ceiling-mounted utilities, mobile casework, and equipment that can easily be reconfigured. Areas can be equipped with a robust utility infrastructure, clean power systems, and utilities and controls that are accessible in a mezzanine above the ceiling.

The Team Advantage

It takes a village to address the many complex considerations involved in designing and constructing successful cleanrooms. Once the facility itself is complete, the team must turn its focus to commissioning and validation of the facility and equipment. It is critical to validate the precise installation of tools and finely detailed engineering of piping for hazardous materials, high-purity gases, and specialized power systems to ensure operation to design intent. And all of this takes time. In our experience, planning the schedule backwards (pull-plan), from the validation master plan to the project start, is critical to achieving on-time, on-budget project delivery. This process, best done collaboratively, creates an actionable schedule by building in the required commissioning and validation milestones.

Successfully delivering complex facilities with long occupancy lead times requires project management as well as technical skills. A collaborative team that can run your project on schedule and on budget is absolutely necessary to achieving your goals. With the right partners in place on Day One for your project kickoff, you’ll have a clear (and clean) advantage.

Jeff Schantz

Jeff Schantz, AIA

Science & Technology Sector Leader