William H Howland

US Patent:

6522158, Feb 18, 2003

Filed:

Apr 30, 1997

Appl. No.:

08/847644

Inventors:

Min-Su Fung - Lagrangeville NY
Roger L. Verkuil - Wappinger Falls NY
Gregory S. Horner - Santa Clara CA
William H. Howland - Cortland OH

Assignee:

Keithley Instruments, Inc. - Cleveland OH

International Classification:

G01R 3100

US Classification:

324765, 324767

Abstract:

Corona charges are used to bias a wafer to push down mobile charges and then pull them up during temperature cycles. Mobile charge is measured from the drops in the corona voltage due to the mobile charges. Corrections are made in the measurements for dipole potentials, leakage and silicon band-bending.

US Patent:

6632691, Oct 14, 2003

Filed:

Apr 11, 2002

Appl. No.:

10/120734

Inventors:

William H. Howland - Wexford PA

Assignee:

Solid State Measurements, Inc. - Pittsburgh PA

International Classification:

G01R 3126

US Classification:

438 17, 438 18, 324754

Abstract:

An apparatus for measuring at least one electrical property of a semiconductor wafer includes a probe including a shaft having at a distal end thereof a conductive tip for electrically communicating with an object area of the semiconductor wafer. The apparatus further includes a device for applying an electrical stimulus between the conductive tip and the object area, and a device for measuring a response of the semiconductor wafer to the electrical stimulus and for determining from the response the at least one electrical property of the object area of the semiconductor wafer. A probe guard is included and surrounds the shaft of the probe adjacent the distal end of the probe. The probe guard also insulates the conductive tip from the semiconductor wafer.

US Patent:

6657454, Dec 2, 2003

Filed:

Mar 15, 2002

Appl. No.:

10/099207

Inventors:

William H. Howland - Wexford PA

Assignee:

Solid State Measurements, Inc. - Pittsburgh PA

International Classification:

G01R 2726

US Classification:

324765, 3241581

Abstract:

A method for measuring threshold voltage and average surface doping concentration of a semiconductor wafer begins by exposing a measurement site to a high intensity light immediately before a measurement sweep begins. A CV measurement sweep is made with the voltage increasing to a maximum voltage, and the response of the semiconductor wafer to CV measurement sweep is recorded. When the voltage is at the maximum voltage, the light is turned off and the capacitance of the measurement site in the absence of light is measured until the capacitance reaches equilibrium. From the recorded response, the threshold voltage and the average surface doping concentration are determined.

US Patent:

6741093, May 25, 2004

Filed:

Mar 18, 2002

Appl. No.:

10/100437

Inventors:

William H. Howland - Wexford PA
Robert J. Hillard - Avalon PA

Assignee:

Solid State Measurements, Inc. - Pittsburgh PA

International Classification:

G01R 3102

US Classification:

324765

Abstract:

A product semiconductor wafer has integrated circuits separated by scribe lines. A probe having an elastically deformable, electrically conductive tip is moved into contact with one of the scribe lines thereby forming a test structure. A suitable electrical stimulus is applied to the test structure and a response of the test structure to the electrical stimulus is measured. At least one property of the product semiconductor wafer is determined from the response.

US Patent:

6771092, Aug 3, 2004

Filed:

Nov 18, 2002

Appl. No.:

10/298778

Inventors:

Min-Su Fung - Lagrangeville NY 12540
Roger L. Verkuil - Wappinger Falls NY 12590
Gregory S. Horner - Santa Clara CA 95051
William H. Howland - Cortland OH 44410

International Classification:

G01R 3102

US Classification:

324765, 324750

Abstract:

Corona charges are used to bias a wafer to push down mobile charges and then pull them up during temperature cycles. Mobile charge is measured from the drops in the corona voltage due to the mobile charges. Corrections are made in the measurements for dipole potentials, leakage and silicon band-bending.

US Patent:

6788076, Sep 7, 2004

Filed:

Jul 9, 2003

Appl. No.:

10/616641

Inventors:

William H. Howland - Wexford PA

Assignee:

Solid State Measurements, Inc. - Pittsburgh PA

International Classification:

G01R 2708

US Classification:

324717, 324658

Abstract:

An apparatus for measuring at least one electrical property of a semiconductor wafer includes a probe including a shaft having at a distal end thereof a conductive tip for electrically communicating with an object area of the semiconductor wafer. The apparatus further includes a device for applying an electrical stimulus between the conductive tip and the object area, and a device for measuring a response of the semiconductor wafer to the electrical stimulus and for determining from the response the at least one electrical property of the object area of the semiconductor wafer. A probe guard is included and surrounds the shaft of the probe adjacent the distal end of the probe. The probe guard also insulates the conductive tip from the semiconductor wafer.

US Patent:

6836139, Dec 28, 2004

Filed:

Oct 22, 2002

Appl. No.:

10/277689

Inventors:

William H. Howland - Wexford PA

Assignee:

Solid State Measurments, Inc. - Pittsburgh PA

International Classification:

G01R 3126

US Classification:

324766, 3241581

Abstract:

A charge carrier lifetime of a semiconductor wafer is measured by contacting an electrically conductive measurement probe to a surface of a semiconductor wafer to form a capacitor. A DC voltage having an AC voltage superimposed thereon is applied to the capacitor and the DC voltage is swept between a first voltage and a second voltage. At the second voltage, the semiconductor wafer adjacent the contact between the measurement probe and the surface of the semiconductor wafer is exposed to a light pulse. After the light pulse terminates, a change in the capacitance of the capacitor over time is determined. From the thus determined change in capacitance, a charge carrier lifetime of the semiconductor wafer is determined.

US Patent:

6842029, Jan 11, 2005

Filed:

Apr 11, 2002

Appl. No.:

10/120661

Inventors:

William H. Howland - Wexford PA, US

Assignee:

Solid State Measurements, Inc. - Pittsburgh PA

International Classification:

G01R 3102

US Classification:

324765

Abstract:

A multi-probe assembly includes a chuck assembly configured to receive a back or front surface of a semiconductor wafer. A multi-probe holder has a plurality of probes each having an elastically deformable conductive tip movable into contact with a front surface of a dielectric or a front surface of a semiconducting material. A means applies an electrical stimulus to each tip, measures a response to the electrical stimulus, and determines at least one electrical property of the dielectric and/or the semiconducting material. A method for measuring at least one electrical property applies a probe (or plurality of probes) having an elastically deformable conductive tip to a scribe line(s). An electrical stimulus is applied to the probe or one of the probes with the remaining probes grounded. A response to the electrical stimulus is measured and at least one electrical property of the semiconductor wafer is determined from the response.