Inspection system and apparatus

• US 7,103,482 B2
• Filed: 08/05/2004
• Issued: 09/05/2006
• Est. Priority Date: 02/03/2003
• Status: Expired due to Fees

• Current Assignee: Qcept Investments, LLC
• Original Assignee: Qcept Technologies, Inc.
• Inventors: Steele, M. Brandon, Hawthorne, Jeffrey Alan, Kim, Chunho, Sowell, David C.
• Primary Examiner(s): Bui, Bryan
• Assistant Examiner(s): Walling, Meagan S
• Application Number:
  US10/710,836
• Publication Number:
  US 20050059174A1
• Time in Patent Office: 761 Days
• Field of Search: 702/35, 702/36, 324/765, 438/12, 438/200, 438/906, 134/1.2, 134/1.3
• US Class Current: 702/35
• CPC Class Codes: G01N 2033/0095 Semiconductive materials
• CPC Class Codes: G01N 27/002 by investigating the work function voltage

Abstract

A method and system for identifying a defect or contamination on a surface of a material. The method and system involves providing a material, such as a semiconductor wafer, using a non-vibrating contact potential difference sensor to scan the wafer, generate contact potential difference data and processing that data to identify a pattern characteristic of the defect or contamination.

Claims

1. A method of inspecting a sample'"'"'s surface with an inspection system, comprising the steps of:

providing a sample having a surface;

providing a non-vibrating contact potential probe;

scanning the sample'"'"'s surface with the non-vibrating contact potential probe by causing relative motion between the non-vibrating contact potential probe and the sample'"'"'s surface;

measuring contact potential difference between the sample'"'"'s surface and the non-contact potential probe;

generating a first signal portion characteristic of a topographical feature of the sample'"'"'s surface and further having a second signal portion representing chemical features of the sample'"'"'s surface.

2. The method of inspecting a sample'"'"'s surface of claim 1 further comprising the step of amplifying the topographical signal relative to the chemical signal.

3. The method of inspecting a sample'"'"'s surface of claim 1 further comprising the step of biasing a portion of the inspection system.

4. The method of inspecting a sample'"'"'s surface of claim 3 further comprising the steps of:

providing a negative bias voltage to a portion of the inspection system chosen from the group consisting of the non-vibrating contact potential difference probe, the sample, and combinations thereof;

providing a positive bias voltage of substantially equal but opposite charge as the negative bias voltage to the portion of the inspection system to which the first bias voltage was applied; and

subtracting the negative bias signal from the positive bias signal.

5. The method of inspecting a sample'"'"'s surface of claim 1, wherein the relative motion is accomplished by rotating the sample about a central axis with the probe tracing tracks of data at varying radii.

6. The method of inspecting a sample'"'"'s surface of claim 5, further comprising the step of decreasing rotational velocity in proportion with the motion of the probe to provide the probe with substantially even data density.

7. The method of inspecting a sample'"'"'s surface of claim 1 further comprising the step of providing a plurality of non-vibrating contact potential difference probes.

8. The method of inspecting a sample'"'"'s surface of claim 7, wherein the plurality of probes are arranged in a linear array.

9. The method of inspecting a sample'"'"'s surface of claim 7, wherein the plurality of probes are arranged in a two-dimensional array.

10. The method of inspecting a sample'"'"'s surface of claim 7 further comprising the step of providing the plurality of probes at a plurality of heights.

11. The method of inspecting a sample'"'"'s surface of claim 7 further comprising the step of providing a voltage bias to the plurality of probes.

12. The method of inspecting a sample'"'"'s surface of claim 1, wherein the relative motion is provided by moving the non-contact potential difference probe with respect to the sample which is maintained substantially stationary.

13. The method of inspecting a sample'"'"'s surface of claim 1, wherein the relative motion is provided by moving the sample with respect to the non-vibrating contact potential probe which is substantially stationary.

14. The method of inspecting a sample'"'"'s surface of claim 1 further including the step of providing a height sensor.

15. The method of inspecting a sample'"'"'s surface of claim 1, further including the step of calibrating the height of the non-vibrating contact potential difference probe to measurements made by the height sensor.

16. The method of inspecting a sample'"'"'s surface of claim 1, wherein the step of calibrating the height of the non-vibrating contact potential difference probe to measurements made by the height sensor further comprises the steps of:

positioning the height sensor above a reference surface so that the distance between the reference surface and the height sensor is within a range of detection for the height sensor;

recording the height of the sensors as z1;

recording the height of the height sensor reading above a reference point as h1;

moving the non-vibrating contact potential sensor to a position above the reference point on the reference surface;

slowly moving the non-vibrating contact potential sensor down towards the reference surface while monitoring the level of the non-contact potential difference probe signal; and

recording as z2 the height when the non-vibrating contact potential difference probe contacts the reference surface as indicated by a significant change in the output of the non-vibrating contact potential difference probe.

17. The method of inspecting a sample'"'"'s surface of claim 16 further comprising the step of positioning the non-vibrating contact potential difference probe at a desired height of h* by the steps of:

positioning the height sensor above the surface so that the surface is within a measurement range of the height sensor;

recording this height as z3 and the height sensor reading as h3;

positioning the non-vibrating contact potential probe above the point z3; and

adjusting the height to z*=z3−

(h3−

h1)−

(z1−

z2)+h*, wherein the height of the non-vibrating contact potential difference probe is located above the surface of point z3 at height h*.

18. The method of inspecting a sample'"'"'s surface of claim 1, wherein the sample comprises an liquid crystal panel.

19. The method of inspecting a sample'"'"'s surface of claim 1, wherein the sample comprises a semiconductor wafer.

20. A system for identifying features on the surface of a sample comprising:

a non-vibrating contact potential difference sensor;

a mechanism for causing relative motion between the sample and the non-vibrating contact potential difference sensor;

a mechanism for measuring contact potential difference between the sample and the non-vibrating contact potential probe;

a generated signal representing the contact potential difference; and

a generated bias voltage applied to a portion of the system chosen from the group consisting of the sample, the non-vibrating contact potential probe, and combinations thereof.

21. The system for identifying features on the surface of a sample of claim 20 further comprising a plurality of non-vibrating contact potential probes.

22. The system for identifying features on the surface of a sample of claim 20 further comprising a height sensor.

23. The system for identifying features on the surface of a sample of claim 20, further comprising a voltage bias applied to a portion of the system.

24. A system for inspecting the surface of a sample comprising:

a non-vibrating contact potential difference sensor;

a chuck for rotating the sample about a central axis;

the chuck having a variable speed control mechanism for changing rotational velocity in proportion with the motion of the probe to provide the probe with substantially even data density; and

a source of data representing a contact potential difference between the non-vibrating contact potential difference sensor and the surface of the sample.