US3668523A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrical testing of dielectric layers, exhibiting voltage dependent capacitance, with linear ramp voltages
Assignee: AT&T Inc
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Filing: 1969-05-07
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Granted: 1972-06-06
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Expires: 1989-05-07
Abstract
Abstract In order to test a dielectric layered structure exhibiting a voltage dependent capacitance, a metal-insulator-semiconductor (M-I-S) structure for example, a linear ramp (sawtooth) voltage is applied across the structure initially in thermal equilibrium, but at a temperature below which the insulator allows ionic impurities to become mobile. The profile of current vs. time, which thereby flows through the structure, constitutes a signal which can be rapidly electronically processed to yield information about the quality and properties of the structure.
Inventors
- 👤 Matthew Kuhn
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 13:17
CPC Classifications
G; G01; G01R; G01R27/00; G01R27/02; G01R27/26; G01R27/2605; G01R27/2617; G01R27/2623; G01R31/00; G01R31/26; G01R31/2607; G01R31/2637
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
82 words
The method of electrically testing a two terminal structure having a voltage dependent capacitance in response to voltages applied across the structure, which comprises the steps of: a. maintaining said structure in a state which is essentially devoid of significantly mobile charges; b. applying a linear ramp voltage across said structure in said state; c. monitoring the instantaneous current through the structure in said state while said voltage is applied thereto in the absence of any other time varying voltage applied thereto.
Claim 2
Independent Claim
82 words
The method of electrically testing a two terminal structure having a voltage dependent capacitance in response to voltages applied across the structure, which comprises the steps of: a. maintaining said structure in a state which is essentially devoid of significantly mobile charges; b. applying a linear ramp voltage across said structure in said state; c. monitoring the instantaneous current through the structure in said state while said voltage is applied thereto in the absence of any other time varying voltage applied thereto.
Claim 3
Dependent Claim
15 words
The method recited in claim 1 in which the structure is a metal-insulator-semiconductor layered structure.
Claim 4
Dependent Claim
32 words
The method recited in claim 2 in which the insulator is characterized by a voltage independent capacitance, and the semiconductor is characterized by a voltage dependent capacitance in response to applied voltages.
Claim 5
Dependent Claim
50 words
The method of testing a structure in accordance with claim 2 in which the period of a single ramp of the linear ramp voltage is sufficient for the formation of an inversion layer in the semiconductor at some time while the linear ramp voltage is being applied to the structure.
Claim 6
Dependent Claim
54 words
The method of testing a structure in accordance with claim 2 which includes the added step of applying to the structure a flat voltage pulse, prior to the step of applying the linear ramp voltage, sufficient to create an inversion layer in the semiconductor when the linear ramp voltage is applied to the structure.
Claim 7
Dependent Claim
45 words
The method of testing a structure in accordance with claim 2 which comprises the further step of shining light upon the structure prior to the step of applying the linear ramp voltage, sufficient to create an inversion layer when the linear ramp voltage is applied.
Claim 8
Dependent Claim
31 words
The method recited in claim 2 in which the semiconductor is essentially silicon and the linear ramp voltage is characterized by a slope of less than approximately 1 volt per second.
Claim 9
Dependent Claim
37 words
The method of electrically testing a structure according to claim 1 in which the step of monitoring is performed by means which include an electronic current monitoring device whose output is fed to a cathode ray oscilloscope.
Claim 10
Independent Claim
122 words
The method of electrically testing a two-terminal, metal-insulator-semiconductor, layered structure in which the insulator is characterized by a voltage independent capacitance and the semiconductor is characterized by a voltage dependent capacitance in response to applied voltages, which comprises the steps of: a. maintaining said structure in a state which is essentially devoid of significantly mobile charges; b. applying a linear ramp voltage across said structure in said state; c. monitoring the instantaneous current through the structure in said state while said voltage is applied thereto; d. monitoring the difference between the instantaneous current and the initial value thereof, to produce a time-dependent electric signal which is proportional to said difference; and e. integrating electrically said signal over a predetermined period of time.
Claim 11
Independent Claim
122 words
The method of electrically testing a two-terminal, metal-insulator-semiconductor, layered structure in which the insulator is characterized by a voltage independent capacitance and the semiconductor is characterized by a voltage dependent capacitance in response to applied voltages, which comprises the steps of: a. maintaining said structure in a state which is essentially devoid of significantly mobile charges; b. applying a linear ramp voltage across said structure in said state; c. monitoring the instantaneous current through the structure in said state while said voltage is applied thereto; d. monitoring the difference between the instantaneous current and the initial value thereof, to produce a time-dependent electric signal which is proportional to said difference; and e. integrating electrically said signal over a predetermined period of time.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-06-06 | 1975-12-06 | 1976-06-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-06-06 | 1979-12-06 | 1980-06-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-06-06 | 1983-12-06 | 1984-06-06 | $7700.00 | Window Closed / Lapsed |