Method for measuring stress induced leakage current and gate dielectric integrity using corona discharge
First Claim
1. A method of characterizing a dielectric layer disposed on a semiconductor wafer, the method comprising:
- positioning the semiconductor wafer relative to a test device;
depositing on a surface of the dielectric layer a corona ionic charge at a rate and fluence sufficient to change a tunneling current between the semiconductor wafer and the dielectric layer; and
measuring with the test device, a stress induced leakage current characteristic across the dielectric layer.
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Abstract
SILC characteristics and density of GOI defects of silicon wafers with thin dielectric films (e.g. SiO2) are determined using a non-contact method that does not require any test structures on the wafer. The method includes stressing a dielectric with a corona discharge and measuring the dielectric current-dielectric voltage (I-V) characteristics by monitoring under illumination the corona charge neutralization after stress. An I-V measurement done as function of corona fluence gives SILC characteristics of the wafer. The SILC characteristics are then compared at a constant dielectric field to provide a measure of GOI defect density. The I-V characteristic corresponding to low fluence that does not generate measurable SILC are used to determine a thickness of dielectric film.
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Citations
30 Claims
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1. A method of characterizing a dielectric layer disposed on a semiconductor wafer, the method comprising:
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positioning the semiconductor wafer relative to a test device;
depositing on a surface of the dielectric layer a corona ionic charge at a rate and fluence sufficient to change a tunneling current between the semiconductor wafer and the dielectric layer; and
measuring with the test device, a stress induced leakage current characteristic across the dielectric layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of measuring gate oxide integrity of a dielectric layer disposed on a semiconductor wafer, the method comprising:
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illuminating the dielectric layer with a light source to remove a voltage drop across the space charged region of the semiconductor wafer, and applying a charge to the dielectric layer with a deposition rate sufficient to stress the semiconductor wafer to induce a tunneling current flow. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A method of measuring gate oxide integrity of a dielectric layer disposed on a semiconductor wafer, the method comprising:
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moving the wafer into position below a charge source, illuminating an area of the wafer under the source with a first light source, setting charging conditions of the charge source, turning on the charge source to stress the area of the wafer, turning off the charge source and the first light source, moving a probe above the wafer over the area stressed by the charge source, illuminating the area of the wafer under the probe with a second light source, measuring the contact potential as a function of time after turning off the charge source, and calculating oxide current density as a function of oxide field. - View Dependent Claims (25)
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26. A method of measuring the gate oxide integrity of a dielectric layer disposed on a semiconductor wafer, the method comprising:
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measuring a stress induced leakage current across the dielectric layer on the wafer, determining a magnitude of the stress induced leakage current as a function of an oxide electric field strength, and comparing the magnitude of stress induced leakage current to a standard magnitude of stress current at an oxide electric field strength, wherein the stress results from a corona ionic charge being deposited on a surface of the dielectric layer at a rate and a fluence sufficiently high to change a tunneling current between the semiconductor wafer and the dielectric layer. - View Dependent Claims (27, 28, 29)
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30. A method of measuring a thickness of a dielectric layer disposed on a semiconductor wafer, the method comprising:
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applying a charge to the dielectric layer at a level sufficient to stress the semiconductor wafer to produce a tunneling current between the semiconductor wafer and the dielectric layer, the tunneling current being related to the thickness of the dielectric layer, measuring a current-voltage characteristic of the semiconductor wafer after applying the charge to the dielectric layer, calculating an oxide current density as a function of oxide field, and determining the dielectric thickness from the calculated oxide current density and oxide field.
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Specification