I SL Annual Conference 2013 · I2SL is a Registered Provider with The American Institute of Architects Continuing Education Systems. Credit earned on completion of this program will

I2SL Annual Conference2013

Minneapolis, Minnesota

Nano-Scaled Interdisciplinary Research: No Small Task

Nanotechnology Cleanroom Environmental Conditions and

Energy Efficiency

September 25, 2013Session D3

Paul Lemestre, PE, LEED AP

Research Facilities Design

I2SL is a Registered Provider with The American Institute of Architects Continuing Education Systems. Credit earned on completion of this program will be reported to CES Records for AIA members. Certificates of Completion for non-AIA members are available on request.

This program is registered with the AIA/CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any material or product. Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation.

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© Research Facilities Design

LEARNING OBJECTIVES

1. Learn about nanotechnology research work in the cleanroom for semiconductor research facilities.

2. Learn about the stringent environmental requirements for personnel and equipment inside the cleanroom and their impact on design and energy.

3. Discuss design and operation strategies to help achieve energy savings for cleanroom operations.

LEARNING OBJECTIVES




NANOTECHNOLOGY CLEANROOM RESEARCH

How small is small?


How small is small?

1 Micron (micrometer) = 0.001 millimeter = 1x10-6 meter


How small is small?



How small is small?


ISO Cleanroom Classification

Source: 2007 ASHRAE Handbook – HVAC Applications


How small is small?

1 nanometer = 0.001 micron = 1x10-9 meter

� formally known as millimicron (1/1000 micron)� one billionth of a meter� 10 Angstroms (1x10-10 meter)


E-Beam

Lithography

Deposition

Coating

Bake

Wafer

Handling

Etching

Resolution <20nm

Some down to 8-10nm

45nm IC chip processing

32nm IC chip processing


How small is small?

20 nanometer = 0.020 micron = 1/5 of 0.1micron particle size

LEARNING OBJECTIVES




CLEANROOM ENVIRONMENTAL CONDITIONS

Stringent environmental parameter to support research activities

� Airborne particulate concentration� Temperature� Dewpoint / relative humidity� Light level intensity� Light wavelength spectrum� Sound levels� Air velocity / air currents� Electromagnetic fields� Vibration



� Airborne particulate concentration

Typical testing down to 0.2 micron particle size for certification

ISO Cleanroom Classification

Source: 2007 ASHRAE Handbook – HVAC Applications



� Airborne particulate concentration

� More stringent ISO Class areas require higher air change rates for dilution and filtering

� Higher air change rates = more fan energy� Higher air change rates = more sensible cooling (fan heat)

ISO Class

Direction of

Air Flow

Air Velocity at

Table Level (fpm)

Air Changes Rate

per Hour (10’

ceiling)

HEPA Coverage %

of Ceiling Area

2 Unidirectional 85-100 510-600 100



5 Unidirectional 45-55 270-330 90-100

6 Mixed 25-35 150-210 40-60

7 Mixed 8-16 48-96 20-30

8 Non-Directional 4-6 24-36 10-15

Airflow Requirements for Clean Spaces



� Temperature

� Common operating setpoint range: 66°F – 70°F (19°C – 21°C)� Most process equipment can handle broader range for setpoint� Personnel gowning requires “cooler” setpoint for comfort� Temperature Stability

� Some process equipment very sensitive to temperature “drift”� Chemical “recipes” for research susceptible to temperature

changes� Effect on control instrumentation and PID loop commissioning

� High resolution RTD temperature instrumentation� Example E-Beam Lithography Tool:

� Temperature 21± 1°C� Stability within 0.25°C/hour� Relative Humidity 40% to 70%



� Dewpoint / relative humidity

� Common operating setpoint range: 45% – 50% rh� Most process equipment can handle broad range for setpoint� Personnel gowning requires lower humidity setpoint for comfort� Humidity Stability

� Chemical “recipes” for research susceptible to humidity changes

� Common stability requirement of ±5% rh� Even down to ± 2% rh for some limited areas

� Effect on control instrumentation and PID loop commissioning� Chilled mirror dewpoint sensor

� Example E-Beam Lithography Tool:� Temperature 21± 1°C� Stability within 0.25°C/hour� Relative Humidity 40% to 70%



� Dewpoint / relative humidity (continued)

Make-up

Wet Bulb: 50°F

Dewpoint: 46°F

46 grains/lbm air

Room: 68°F / 45%rh

Make-up

Dry Bulb: 55°F



� Dewpoint / relative humidity (continued)

� Make-up air controls cleanroom humidity with outside air treatment� Dehumidification:

� Low dew point temperature requirement� Lower chilled water system temperature� Separate dehumidification process coil and cooling loop� Depending upon region, significant removal of outside air

moisture during design cooling months� Humidification:

� Clean steam-to-steam / atomizing humidification� Depending upon region, significant loads during design winter

periods.



� Light level intensity� Common design requirement of 80 – 105 fc (860 – 1130 lux) at 30”� Lighting controls for occupancy

� Light wavelength spectrum� UV filtration of light waves (250 – 500 nm range)



� Sound levels� Common design requirement <NC60 at 72” (octive band)

� Air velocity / air currents� Typically average room air velocity dictated by ISO class design� Air currents may induce vibration to sensitive electron optical

columns



� Electromagnetic fields

� Fields through the cleanroom area:� Originating from outside building

� Site electrical� Vehicular traffic� Rail traffic

� Influence inside building� Electrical distribution� Electric motors, elevators

� Site selection and site EMI measurements� Example E-Beam Lithography Tool:

� Magnetic DC Fields vary <80nT (0.8 milligauss) over 2 hours� Horizontal plane stray-fields <0.5 milligauss� Vertical plane stray-fields <0.5 milligauss

Electromagnetic Fields (EMI)


EMI Analysis – AC Magnetic Site Measurements

SE

M

Building Simulation for AC Magnetic Fields



� Vibration

� Common target design of structural slab of VC-E (125 µin/s) or better� Further equipment base isolation as needed

Sample Equipment Site Vibration Requirement

LEARNING OBJECTIVES




CLEANROOM ENERGY REDUCTION STRATEGIES

University of Minnesota Physics and Nanotechnology Building

� ISO Classification of clean spaces� Demand control recirculation airflow rates� Process wet bench and fume hood design� Process cooling water loop for equipment� Envelope design� Lighting controls


University of Minnesota Physics and Nanotechnology Cleanroom Facility

Clean Corr (860 sf)

Clean Bays (4,000 sf)

Support (400 sf)

Gowning (370 sf) Service Chase (4,370 sf)

Total Size=10,000 sf Filtered Area = 52%



� ISO Classification of clean spaces

� Clean Bays 1 – 3: ISO Class 6 (upgradeable to ISO 5 future)� Clean Bays 4 – 5: ISO Class 5� Gowning: ISO Class 6



� Demand control recirculation airflow rates

� Use of in-situ active particle monitoring system� Monitor real-time particle levels in clean bays� Interface with air-handling controls� Enable demand control airflow sequences for recirculating air-

handling units (RAUs)� Reduction in RAU airflow down to 50% design values� Monitor temperature in space – override for sequence to ensure

setpoint stability for research equipment







Source: Berkeley Lab Cleanroom Energy Benchmarking



� Process wet bench and fume hood design

� Limit quantity of exhausted benches and hoods� Eleven (11) wet bench process hoods� One (1) maintenance fume hood

� Limit quantity of exhausted laminar flow benches and hoods� One (1) laminar flow process wet bench� For 8-ft bench, 1,900 cfm (laminar) vs. 1,200 cfm (exhaust only)

� Design opening of wet bench� 16-inch opening� Rotating “flip” face shield to increase opening for maintenance



� Process cooling water loop for equipment

� Closed loop cooling water for equipment connection in service chases

� Dedicated heat exchangers, pumps, accessories for cleanroom� Elevated supply water temperature above dewpoint (60°F – 65°F)� Variable speed pump flow to match system demand



� Envelope design

� Focus on moisture barrier at cleanroom perimeter� Limit migration of moisture in/out of cleanroom through envelope� Reduce need for humidification/dehumidification from make-up� Exterior walls (for outside air extreme conditions)� Interior walls to adjacent spaces (corridor, lobby)

� Vapor barrier� High performance epoxy paint system� Foamed wall insulation� Caulked sealed joints (necessary for space pressurization)

� Lighting controls

� Several systems evaluated in design� Owner settled on adjustable countdown timers (simple!)



� ISO Classification of clean spaces� Demand control recirculation airflow rates� Process wet bench and fume hood design� Process cooling water loop for equipment� Envelope design� Lighting controls

Thank you for your time.

Questions?

This concludes The American Institute of Architects Continuing Education Systems Program

Paul Lemestre, PE, LEED AP

Research Facilities Design

Documents

I SL Annual Conference 2013 · I2SL is a Registered Provider with The American Institute of Architects Continuing Education Systems. Credit earned on completion of this program will