A version of our Rigid Quiet Island^® meets the most stringent wafer scanner floor stiffness specifications.

TMC Quiet Island® sub-floor platforms are a modular vibration control solution to the problem of supporting vibration sensitive and/or large, heavy floor-mounted equipment in a raised-floor cleanroom environment.

Because the primary considerations in designing raised floors are access to electrical cabling and the facilitation of air flow, structural rigidity and damping of vibration are generally secondary design goals. Raised floors routinely amplify the relatively quiet sub-floor vibration levels by a factor of 100 to 1,000. In addition, the high acoustic noise levels generated by sophisticated air handling systems further excite raised floors. The result is a vibration environment that is incompatible with sub-micron wafer manufacturing and inspection equipment.

Conventional solutions to this problem include poured-in-place concrete pedestals and costly, needlessly complex, custom-engineered structures.

Both approaches suffer from a lack of portability, adaptability and performance.

TMC Quiet Island sub-floor platforms consist of a high-stiffness, high-damping stainless steel floor platform supported by one of our interchangeable support stands. The stand may be our non-resonant rigid tripod or rigid square tube type leveling jack stand, patented Gimbal Piston™ Air Isolators or patented STACIS® Active Piezoelectric Vibration Cancellation System. The vibration sensitivity of your application will determine whether rigid stands are appropriate or a passive or active vibration isolation system is required.

Platform
The platform is a 2 1/2 in. (60 mm) or 4 in. (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 structural damping. The large cross-section and steel content yield a very high level of overall rigidity. For a complete discussion of this laminated construction, see the Top Plate Design Alternatives page.

Support Stands
The modular design of Quiet Island support stands adapts to changing requirements. The supports may be field upgraded at any time without moving the platform or supported instrument.

Rigid Leveling Stands 
Instruments with less sensitivity to mechanical vibration or effective internal vibration isolation may be adequately supported on rigid leveling stands. TMC rigid stands are designed to minimize amplification of sub-floor vibration levels, provide a foundation that is much stiffer and less resonant than the raised floor and allow the option of upgrading to an isolator in the future. The stands consist of square posts with
a rigid screw jack mechanism and jam nut to support the platform. A heavy-duty tripod leveling stand is preferred for taller floors and applications requiring the stiffest support structure. A rigid leveling stand version of our Quiet Island is ideal for applications where the sub-floor vibration levels meet the tool vibration criteria. Our Rigid-Damped Tripod is a new offering that requires no platform but rather can be placed under individual feet of the tool.
See the Rigid-Damped Tripod page for a complete discussion.

A number of tripods, quads stands and square post designs exist. Our recommendations will depend on your floor height, sub-floor geometry and application..

Some vibration sensitive applications will require Gimbal Piston™ Isolators, which offer effective passive vibration isolation. These isolators have low vertical and horizontal natural frequencies and can achieve excellent vibration control isolation above 5-10 Hz. Isolators for raised floors above 30 in. (750 mm) are rigidly connected with tiebars for safety and stability. Shorter posts are independent, with oversized baseplates for increased stability. Standard features include rugged aluminum height control valves, internal piston travel restraints, thin-wall dacron reinforced rubber diaphragms and non-oil based pneumatic damping techniques. See the Gimbal Piston Isolator page for a complete discussion. Note that a Gimbal Piston version of Quiet Island may be incompatible with the internal vibration isolation system of the tool being supported.

STACIS^®
For the ultimate in vibration control beneath a raised floor the STACIS® Active Piezoelectric Active Vibration Cancellation System may be combined with our platform laminations. STACIS provides vibration isolation actively from 0.2 Hz to 250 Hz and passively at higher frequencies. The improvement in vibration control isolation performance in comparison to an air isolator is two orders-of-magnitude at 2 Hz. The STACIS system will not only bring a noisy sub-floor back to within spec, but is compatible with all tool internal vibration isolation systems and has been shown to possibly increase stepper yield in quiet environments. See the STACIS page for a complete discussion of STACIS.

STACIS^® 2100

Counter-Mass
Loaded platforms on passive air isolators, may require a counter-mass to maintain stability. The minimum separation between the isolator centers must meet certain criteria (see the Technical Background), or self-oscillation may occur. To maintain a low center of mass, a counter-mass is generally required. Quiet Islands with rigid mounts or STACIS active piezoelectric supports DO NOT require a counter-mass


How to Order
Because of the complexity, vibration sensitivity, and value of the equipment installed on our Quiet Island sub-floor platforms, we do not maintain standard catalog numbers for ordering. We consider each installation to be a custom-engineered solution. The recommended procedure for ordering is as follows:

Gimbal Piston™ Air Isolator version of
Quiet Island^® (with counter-mass)  

• Tell us what equipment or instrument you want to isolate. Because of our installed base, it is likely that we have already engineered a platform design to the requirements of your application. In addition, we maintain close contact with stepper, aligner, SEM, and other tool manufacturers to keep current with size, shape, weight changes, and floor vibration specifications.
• Alternatively, you may want a system to fit within the raised floor grid system. Specifiers often opt for a 47 x 47 in. (1190 x 1190 mm) platform to replace an even number of floor tiles.
• Tell us the height of your raised floor above the solid sub-floor.
• Describe to us or provide an illustration showing any hole pattern in your sub-floor or the steel beam/waffle slab geometry.
• Provide us with floor vibration data or discuss with us how to arrange to have this data measured.
• Consider the vibration sensitivity of the instrument. Many tools are adequately supported by our rigid, non-resonant post design. More vibration sensitive applications will require air or piezoelectric support.