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Membrane Head

Keltech Membrane Head
Keltech Membrane Head on Lapper

Grooved-Membrane Head Function

The grooved-membrane head is used to polish silicon semiconductor

wafers on a rotary lapper machine. Wafers are quickly attached to the

flexible membrane with vacuum, using shallow grooves on the flat

surface of the membrane. The rotating head positions the wafers in

abrading contact with rotating fixed-abrasive discs that are attached to

the precision-flat rotating platen.


Micron-Sized Abrasive Particles

Small abrasive particles having selected sizes of 3 micron or smaller

can be chosen from a wide range of abrasive materials to uniformly

remove nanometer amounts of material from the polished silicon wafers.

Rigid Retainer Ring Eliminated

The rigid retainer ring used on conventional membrane-type wafer polishing heads is eliminated. Instead of capturing the wafer within the rotating retainer ring, the wafer is attached to the flexible membrane with vacuum. The membrane is held in place on the head to resist lateral friction type abrading forces by an annular system of pins that slide vertically in matching pin-hole receptacles in the head.  The flexible elastomeric membrane “floats” in a vertical direction while controlled abrading pressure is applied uniformly across the full abraded surface of the wafer.

High Speed Wafer Polishing

Abrasive discs having abrasive coated islands allow a large increase in the abrading speeds of the wafers. These water mist cooled fixed-abrasive discs can be operated at much higher abrading speeds than conventional liquid abrasive slurry abrading systems. The disc islands prevent hydroplaning of the wafers at the high abrading speeds.


Multiple Pressure Chamber Head

Multiple annular pressure chambers in the head can provide different abrading pressures in different portions of the flexible elastomer membrane. These independent pressure chambers allow the amount of material removed from selected portions of a wafer to be controlled by simply adjusting the abrading air pressure supplied to each chamber.

Use with CMP Slurry Pads

The grooved-membrane heads can also be used with resilient chemical mechanical planarization (CMP) pads and liquid abrasive slurries to polish silicon wafers.


Retrofit Grooved -Membrane Heads

These grooved-membrane heads can be retrofitted on the many conventional flexible membrane wafer polishing heads that are in widely used today. These relatively inexpensive heads can provide superior performance at any abrading speeds.

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