Calibration of non-vibrating contact potential difference measurements to detect surface variations that are perpendicular to the direction of sensor motion

• US 7,752,000 B2
• Filed: 05/02/2008
• Issued: 07/06/2010
• Est. Priority Date: 05/02/2008
• Status: Expired due to Fees

• Current Assignee: Qcept Investments, LLC
• Original Assignee: Qcept Technologies, Inc.
• Inventors: Schulze, Mark A., Usry, William R.
• Primary Examiner(s): Dunn, Drew A
• Assistant Examiner(s): VO, HIEN XUAN
• Application Number:
  US12/151,054
• Publication Number:
  US 20090276176A1
• Time in Patent Office: 795 Days
• Field of Search: 702/85, 324/158.1, 731/04, 731/05
• US Class Current: 702/85
• CPC Class Codes: G01N 27/002 by investigating the work function voltage
• CPC Class Codes: H01L 22/14 for electrical parameters, e.g. resistance, deep-levels, CV, diffusions by electrical means

Abstract

A method and system for determining the contact potential difference of a wafer surface using a non-vibrating contact potential difference probe and a vibrating contact potential difference probe. The method and system involves scanning the wafer surface with a non-vibrating contact potential difference sensor, integrating and scaling the resulting data, and applying offsets to individual tracks of data to match the integrated scaled data to measurements made using a vibrating contact potential difference sensor.

Claims

1. A method of determining the contact potential difference of a surface of a material to characterize properties of the surface, comprising the steps of:

providing a surface of a material;

providing a contact potential difference sensor having a sensor probe tip;

scanning the surface and contact potential difference sensor relative to one another;

generating laterally-scanned sensor data representative of changes in contact potential difference between the sensor probe tip and the surface of the material as the sensor probe tip scans laterally relative to the surface of the material;

processing the laterally-scanned sensor data to provide relative contact potential difference values;

using a vibrating contact potential difference sensor to make at least one measurement of the absolute contact potential difference of the laterally-scanned surface; and

using the absolute contact potential difference data to calculate offsets which are added to the relative contact potential values to generate characteristic data which is representative of the contact potential difference between the sensor probe tip and all points on the laterally scanned surface, thereby characterizing properties of the surface of the material.

2. The method as defined in claim 1 wherein the step of processing the laterally scanned sensor data comprises integrating the laterally-scanned sensor data to produce integrated data.

3. The method as defined in claim 2 wherein the step of processing the laterally-scanned sensor data comprises multiplying the integrated data by a scaling factor to convert the laterally-scanned sensor data to the relative contact potential difference values.

4. The method as defined in claim 1 where the lateral scanning motion is generated by rotating the wafer.

5. The method as defined in claim 1 where the laterally scanned sensor data is provided as concentric circular tracks data.

6. The method as defined in claim 1 where the step of making vibrating contact potential difference measurements comprises accumulating data on different tracks.

7. The method as defined in claim 1 further including the step of analyzing the characteristic data to determine variation in surface contact potential difference perpendicular to the direction of travel of the probe tip during scanning.

8. The method as defined in claim 1 further including the step of subjecting the surface of the material to a plurality of different treatments and characterizing the surface of the material to accumulate correlation data associated with each of the different treatments to enable producing predetermined surface qualities for the material.

9. The method as defined in claim 8 wherein the correlation data is further used to pre-program production of a plurality of types of the material having the predetermined surface qualities.

10. The method as defined in claim 8 wherein the different treatments are selected from the group of a cleaning process, a chemical treatment process and a physical treatment process.

11. The method as defined in claim 10 wherein the cleaning process is selected from the group of cleaning by applying a deionized wash and by applying a plasma processing step.

12. A method of determining the contact potential difference of a surface of a material to characterize properties of the surface, comprising the steps of:

providing a surface of a material;

providing a contact potential difference sensor having a sensor probe tip;

scanning the surface and contact potential difference sensor relative to one another;

generating a first set of laterally-scanned sensor data representative of changes in contact potential difference between the sensor probe tip and the surface of the material as the sensor probe tip scans laterally relative to the surface of the material;

generating a second set of laterally-scanned sensor data representative of changes in contact potential difference across the surface of the material, the second set of sensor data being generated by moving the contact potential difference sensor perpendicular to the direction of the laterally scanning of the first set of sensor data;

processing the first and second set of sensor data to determine relative contact potential difference values;

using a vibrating contact potential difference sensor to make at least one measurement of the absolute contact potential difference of the laterally-scanned surface using a vibrating contact potential difference sensor; and

using the absolute contact potential difference data to calculate offsets which are added to the integrated, scaled non-vibrating relative contact potential difference data values to generate characteristic data which is representative of the contact potential difference between the sensor probe tip and all points on the laterally scanned surface, thereby characterizing properties of the surface of the material.

13. The method as defined in claim 12 wherein the step of processing the laterally scanned sensor data comprises integrating the laterally-scanned sensor data to produce integrated data.

14. The method as defined in claim 12 wherein the step of processing the laterally-scanned sensor data comprises multiplying the integrated data by a scaling factor to convert the laterally-scanned sensor data to the relative contact potential difference values.

15. A semiconductor wafer prepared for use in an electronic component, at least one of the methods of processing including the steps of:

providing a semiconductor wafer having a surface;

providing a contact potential difference sensor having a sensor probe tip;

scanning the surface of the semiconductor wafer and contact potential difference sensor relative to one another;

generating laterally-scanned sensor data representative of changes in contact potential difference between the sensor probe tip and the surface of the semiconductor wafer as the sensor probe tip scans laterally relative to the surface of the semiconductor wafer;

processing the laterally-scanned sensor data to provide relative contact potential difference values;

using a vibrating contact potential difference sensor to make at least one measurement of the absolute contact potential difference of the laterally-scanned surface; and

using the absolute contact potential difference data to calculate offsets which are added to the relative contact potential values to generate characteristic data which is representative of the contact potential difference between the sensor probe tip and all points on the laterally scanned surface, thereby characterizing properties of the surface of the semiconductor wafer.

16. The method as defined in claim 15 wherein the step of processing the laterally scanned sensor data comprises integrating the laterally-scanned sensor data to produce integrated data.

17. The method as defined in claim 16 wherein the step of processing the laterally-scanned sensor data comprises multiplying the integrated data by a scaling factor to convert the laterally-scanned sensor data to the relative contact potential difference values.

18. The method as defined in claim 15 further including the step of analyzing the characteristic data to determine variation in surface contact potential difference perpendicular to the direction of travel of the probe tip during scanning.

19. The method as defined in claim 15 further including the step of subjecting the surface of the semiconductor wafer to a plurality of different treatments and characterizing the surface of the semiconductor wafer to accumulate correlation data associated with each of the different treatments to enable producing predetermined surface qualities for the semiconductor wafer.

20. The method as defined in claim 19 wherein the correlation data is further used to pre-program production of a plurality of types of the semiconductor wafer having the predetermined surface qualities.