Hydrostatic pad pressure modulation in a simultaneous double side wafer grinder
AssigneeMEMC Electronic Materials, Inc.
InventorsSumeet S. Bhagavat, Roland R. Vandamme, Tomomi Komura
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Abstract
Systems and methods are disclosed for modulating the hydrostatic pressure in a double side wafer grinder having a pair of grinding wheels. The systems and methods use a processor to measure the amount of electrical current drawn by the grinding wheels. Pattern detection software is used to predict a grinding stage based on the measured electrical current. The hydrostatic pressure is changed by flow control valves at each stage to change the clamping pressure applied to the wafer and to thereby improve nanotopology in the processed wafer.
Claims10
A method of processing a semiconductor wafer using a double side grinder of the type that holds the wafer between a pair of grinding wheels and a pair of hydrostatic pads during a grinding operation, the method comprising:
- establishing a first hydrostatic pressure in the hydrostatic pads to initially clamp the wafer during a first stage of the grinding operation,
- measuring the amount of electrical current used by the grinding wheels of the double side grinder,
- determining the stage of the grinding operation based on the measured amount of electrical current used by the grinding wheels of the double side grinder,
- reducing the hydrostatic pressure to a second hydrostatic pressure lower than the first pressure during grinding of the wafer in a second stage of the grinding operation, and
- increasing the hydrostatic pressure to a third hydrostatic pressure during a third stage of the grinding operation to clamp the wafer and to thereby improve nanotopology in the processed wafer.
A double side grinder comprising a pair of grinding wheels, a processor, a pair of hydrostatic pads, and flow control valves,
- the grinding wheels and hydrostatic pads being operable to hold a generally flat wafer in a plane with a first part of the wafer positioned between the grinding wheels and a second part of the wafer positioned between the hydrostatic pads,
- the processor being operable to measure the amount of electrical current used by the grinding wheels,
- the hydrostatic pads including water flowing therethrough to maintain a hydrostatic pressure,
- the flow control valves operable to controll the water flow rate through the pads and to thereby control the hydrostatic pressure,
- the processor including pattern detection software for detecting various stages of a grinding process based on the measured amount of electrical current used by the grinding wheels,
- the processor operable to control water flow rate through the flow control valves in response to the stage detected by the pattern detection software.
Dependencies are inferred from the claim text.