Acoustic temperature and film thickness monitor and method
OwnerYong J. Lee, Butrus T. Khuri-Yakub +1inventors
InventorsYong J. Lee, Butrus T. Khuri-Yakub, Krishna C. Saraswat
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Abstract
An acoustic temperature and/or film thickness monitoring system for semiconductor wafers in which the velocity of acoustic waves in the wafer is employed to measure temperature and/or thickness.
Claims17
The method of measuring a characteristic of a semiconductor wafer during processing which comprises the steps of
- launching an acoustic wave in the wafer at one location so that the acoustic wave propagates through the wafer,
- measuring the elapsed time required for the acoustic wave to travel between two spaced locations on the wafer, and
- converting said elapsed time to a measure of said characteristic between said two locations;
- wherein the elapsed time is measured between a number of spaced locations and wherein said elapsed times are converted into a profile of the characteristic of said wafer.
The method of measuring a characteristic of a semiconductor wafer while the wafer is being processed in a processing chamber, comprising
- supporting the wafer in the processing chamber on one end of spaced support rods,
- launching an incident longitudinal or shear acoustic wave at the other end of a first of said support rods whereby said incident acoustic wave induces a travelling acoustic wave in the wafer at said one end, said travelling acoustic wave propagating through the wafer,
- measuring the velocity of said travelling acoustic wave between two spaced locations in said wafer, and
- converting said velocity to an indication of said characteristic between said two spaced locations.
The method of measuring one of temperature, thickness, or temperature and thickness of a semiconductor wafer while the wafer is being processed in a processing chamber, comprising
- supporting the water in the processing chamber on one end of spaced support rods,
- launching incident longitudinal or shear acoustic waves at the other end of at least two of said support rods, at different frequencies, whereby said incident acoustic waves induce travelling acoustic waves of different frequencies in the wafer at said one end of said rods, said travelling acoustic waves propagating through the wafer,
- measuring the velocity of said travelling acoustic waves of said different frequencies between two spaced locations in said wafer, and
- converting said velocities to an indication of one of temperature, thickness, or temperature and thickness of the wafer between said two spaced locations.
The method of measuring a characteristic of a semiconductor wafer while the wafer is being processed in a processing chamber, comprising
- supporting the wafer in the processing chamber on one end of spaced support rods,
- launching an incident longitudinal or shear acoustic wave at the other end of at least one of said support rods whereby said incident acoustic wave induces a Lamb wave in the wafer at said one end, said Lamb wave propagating as a fan beam through the wafer,
- measuring the velocity of said Lamb wave in a plurality of directions along said fan beam between two spaced locations in each of said directions in said wafer,
- repeating velocity measurements in a plurality of directions along the fan beam for fan beams launched from different radial positions, and
- processing said velocities to provide a tomographic image of said characteristic.
A system for monitoring a characteristic of a semiconductor wafer during processing, comprising
- a plurality of spaced support rods for supporting the wafer from one end,
- a longitudinal or shear wave transducer mounted on the other end of at least one support rod for inducing incident longitudinal or shear acoustic waves of predetermined frequency in said rod, whereby said incident acoustic waves launch travelling acoustic waves in the wafer,
- means for measuring the velocity of said travelling acoustic waves between two spaced locations, and
- means for converting said velocity to an indication of said characteristic of the wafer between said two spaced locations.
Dependencies are inferred from the claim text.