Title : OPTIMISATION OF AIR FLOW IN MINI-ENVIRONMENT

Authors : Adam GREEN, PHOENICS North America George TANNOUS, ASYST Technologies USA

Date: 1997 - PHOENICS CFD Software

Details:

• Within the semiconductor industry CFD may be applied to aid an engineer in contaminatiom control, for example when optimising the airflow within an enclosure, such as a minienvironment.

• Contaminating particles are either introduced in a process tool through the fan filter unit or produced by the process itself.

• The mini-environment should be designed to eliminate recirculation regions that can lead to contamination build-up in stagnant areas, and to create a positive internal pressure to eliminate cross contamination.

• The mini-environment include an enclosure with a fan filter unit at the top supplying clean air, a porous plate with 10% porosity that supports a process tool and a lower air removal system. (Note that within this environment the particles of concern are considered small enough to ignore inertial and gravitational effects.)

• Three different models were considered, each with the following location for the inlet fan filter unit: Model 1: one quarter of the top of the domain Model 2: left hand side of the domain Model 3: whole of the top of the upper chamber The fan velocity in each case is the same, hence the volume flow rate is different for each model due to the different size of each fan.

Fig 1: Geometric arrangement

Fig 2: Velocity vectors through the mid plane, for Model 1

Fig 3: Velocity vectors through the mid plane, for Model 2

Fig 4: Velocity vectors through the mid plane, for Model 3

Fig 5: Pressure (Pa) at the mid plane, for Model 1

Fig 6: Pressure (Pa) at the mid plane, for Model 2

Fig 7: Pressure (Pa) at the mid plane, for Model 3

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