Method for non-destructive, non-contact measurement of dielectric constant of thin films
AssigneeTexas Instruments Incorporated
InventorsKelly J. Taylor, Wei-Yung Hsu
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Abstract
A method for measurement of dielectric constant of a thin film is disclosed which is non-destructive and avoids contact with the film and the substrate carrying it. A first characteristic of the substrate is measured using a capacitance measuring device. Then, the thin film is deposited on the substrate. The first characteristic of the substrate is measured a second time after the film has been deposited. Thereafter, the true film thickness is measured. A ratio of the measurements made with the capacitance measuring device is then established with the actual thickness measurement. The dielectric constant can then be derived from a lookup table or graph calibrated for the tools being used for the measurements.
Claims4
A method for non-contact, non-destructive measuring of the dielectric constant of a thin film on a semiconductor wafer comprising the steps of:
- (a) measuring a first characteristic of said wafer using a capacitance measuring tool;
- (b) depositing a thin film of a dielectric material on said wafer;
- (c) measuring said first characteristic of said wafer with said thin film deposited thereon using a capacitance measuring tool;
- (d) measuring the true thickness of said thin film;
- and
- (e) forming a ratio of said measurement in step c minus the measurement in step a divided by the measurement in step d and deriving the dielectric constant for said deposited thin film from a calibrated table as a function of said ratio.
A method for non contact, nondestructive measuring of the dielectric constant of a thin film on a semiconductor wafer comprising the steps of:
- placing a wafer between the probes of a capacitive measuring tool and measuring the capacitance C.sub.i therebetween;
- placing a thin film of a dielectric on said wafer;
- placing the film coated wafer between the probes of a capacitive measuring tool and measuring the capacitance C.sub.f therebetween;
- measuring the true thickness t.sub.d of the film deposited on the wafer;
- and calculating the dielectric constant for said thin film using the formula
- K=[1-.beta.(C.sub.f -C.sub.i)/C.sub.f C.sub.i t.sub.d ].sup.-1
- where
- .beta. is a constant which has been determined by experiment to validate said formula for the tools utilized to make said measurements.
A method for non-contact, nondestructive measuring of the dielectric constant of a thin film on a semiconductor wafer comprising the steps of:
- measuring the thickness of said wafer T.sub.prior using a capacitance measuring tool;
- depositing a thin film of a dielectric material on said wafer;
- measuring the thickness of said wafer with said thin film thereon T.sub.post using a capacitance measuring tool;
- measuring the true thickness T.sub.actual of said thin film thereon;
- and
- calculating the dielectric constant for said thin film using the formula
- K=[1-.alpha.(T.sub.post -T.sub.prior)/T.sub.actual ].sup.-1
- where .alpha. is a constant greater than zero and less than or equal to 1 which has been determined by experiment to validate said formula for the tools utilized to make said measurements.
Dependencies are inferred from the claim text.