EC Vacuum Chucks
Mechanical Locating Flat Surface Design

These vacuum chucks are used with the PWM32 Spinner Series and the EC101/PM101 Spinner Series. The flat surface chuck holds thin, flat substrates such as silicon, germanium, gallium arsenide wafers, etc. They fit the 3/8" D-shaft.

Four mechanical locating fingers, 90 degrees apart, provide locating guides for a substrate, either round or rectangular. They are generally used with heavier square or rectangular substrates. The guide fingers are attached to the underside of the chuck and are adjustable in pairs, over the range shown. Different pairs of alignment fingers are used for rectangular substrates. The ends of the alignment fingers bend upward and come above the surface of the chuck. If a substrate is improperly placed sitting on one of the fingers, it will prevent a vacuum seal and the spinner vacuum interlock will prevent spinning the substrate. For the stronger substrates, see the O-ring type mechanical locating chucks. Many special Mechanical Locating chucks are made for special purposes, some with fixed non-adjustable fingers. Also see the recessed chuck designs for substrates with consistent dimensions, where better film uniformity and backside protection is necessary.

If the fingers project above the surface of the substrate, air turbulence can cause local non-uniformity of the coating film, near each finger.

When using flat-surface, or o-ring type chucks, the substrate should overhang the chuck by 1/4" or more, to prevent fluid reaching the surface of the chuck. If fluid reaches the substrate/chuck interface, capillary forces will wick the fluid between the substrate and chuck, thereby fouling the backside of the substrate and the surface of the chuck. Due to the screws holding the fingers, the mechanical locating flat-surface and o-ring chucks are not provided with a plastic disc mounted below the surface of the chuck, with a larger diameter than the substrate, as are the non-mechanical locating designs. The fingers provide the necessary alignment.

The recommended vacuum is 23 "/Hg or more. HRI spinner interlocks are typically set at the factory to operate at about 17 "/Hg, and drop out approximately 1-1/2 "/Hg below the operate point. 23"/Hg or more provides for quickly passing through the operate point, and therefore provides a quick consistent response. The interlock set-point is adjustable, and can be adjusted to a much lower level if necessary, for thin fragile substrates. An accessory vacuum regulator may be required to operate at a consistent vacuum, lower than the source.

Features:

• Flat Surface Finish
• O-Ring Chuck-to-Shaft Seal
• Surface Design Minimizes Substrate Deformation

The chart below shows a variety of mechanical locating flat surface chuck sizes and materials. We have or can custom design chucks of many other sizes and possibly other materials upon request.

Select Below for Information on All Chucks