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Choosing a raised platform for semiconductor facilities

 

Which Quiet Island is right for you?


Most semiconductor facilities have raised floors to handle the cleanliness requirements in the fab. Air flows down from the ceiling and is drawn out under the raised floor along with any particles that might be generated. While raised floors are easily capable of supporting humans walking about and small pieces of equipment, they are typically not used to support environmentally sensitive processing equipment commonly used in chip manufacturing. Instead, these tools are often installed on raised pedestals. How is a semiconductor manufacturer to know what kind of raised pedestal to use for different pieces of equipment?

In this video, Mike Georgalis, TMC’s North American Sales Manager, discusses the options to consider when choosing a raised floor pedestal.


The problem:


Is your piece of equipment sensitive to vibration? If so, how much vibration can it tolerate?

Some semiconductor processing equipment, such as ion implanters or deposition machines, are fairly insensitive to floor vibration and don’t need special vibration isolated pedestals when being installed or used. Other semiconductor equipment like scanning electron microscopes, transmission electron microscopes, CD inspection tools, lithography tools and many others are susceptible to floor vibrations, which can greatly diminish their performance. How do you know what tools are sensitive to floor vibration?

Ask your vendor


If your vendor doesn’t have a vibration specification for their tool, that probably means it is relatively insensitive to vibration and could be installed on a rigid Quiet Island. What is a rigid Quiet Island?

The raised floor platform is a TMC designed and manufactured 4 inch (100 mm) thick lamination of steel plates sandwiched around a lightweight, incompressible, damped core material. The layering effect of rigid steel plates and core, epoxy bonded into a seamless, stainless-steel pan provides an extremely high level of stiffness and structural damping. The large cross-section and steel content yield a very high level of overall rigidity. The top and sides are a continuous, one-piece, stainless steel shell to preserve cleanliness, appearance, and integrity. TMC designs and manufactures the platforms specific to the application incorporating cutouts, special shapes, tiedown holes, and lifting bolts as required.

Figure 1 Rigid Quiet Island

The Survey

If your tool manufacturer does have a vibration specification, then it’s important to have a vibration survey done of your facility. TMC can be contracted to do a survey, or you can hire a local vibration consultant to do it for you. In either case an engineer will use vibration sensors and data acquisition equipment to monitor your facility for vibration.

If your facility vibration is HIGHER than the tool specification, then you should place the tool on a Quiet Island with STACIS® active vibration isolation. STACIS is the most effective platform for minimizing low frequency floor vibration.
  

raised floor 3d rendering setup

Figure 2 STACIS Quiet Island

If your facility vibration is LOWER than the tool specification, then you have a choice to make. You can install a rigid Quiet Island which should be fine in the near term. However, studies have shown that as facilities ramp up and get busier the vibration in the facility tends to get higher over time. If you are concerned about rising vibration in your facility, it might be prudent to install a Quiet Island with STACIS active vibration isolation right away, or you could start with a rigid Quiet Island and upgrade if necessary.

Quiet Islands come in many shapes and sizes. It’s best to consult with your TMC applications engineer to determine what Quiet Island is best for you.


 

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