Semiconductor wafer inspection system

• US 6,957,154 B2
• Filed: 07/29/2003
• Issued: 10/18/2005
• 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
• Primary Examiner(s): Nghiem, Michael
• Assistant Examiner(s): Walling, Meagan S
• Application Number:
  US10/631,469
• Publication Number:
  US 20040152250A1
• Time in Patent Office: 812 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. An in-line analysis method for identifying a chemical defect present on a surface of a semiconductor wafer being processed in a clean room for production, comprising the steps of:

providing an in-line semiconductor wafer processing system including a semiconductor wafer scanning system for analyzing chemical defects;

providing a semiconductor wafer having a surface;

fixing the semiconductor wafer upon a wafer stage of the semiconductor wafer scanning system;

providing a non-vibrating contact potential difference sensor;

engaging a positioning mechanism in communication with the non-vibrating contact potential sensor whereby the non-vibrating contact potential difference sensor is positionable in relation to the wafer stage via the positioning mechanism and the non-vibrating contact potential difference sensor is positioned in the in-line semiconductor wafer processing system;

continuously radially scanning the non-vibrating contact potential difference sensor about a circumferential track of the semiconductor wafer;

generating contact potential difference track data from the non-vibrating contact potential difference sensor during at least the radial scanning of the semiconductor wafer relative to the sensor the track data being representative of changes along the circumferential track of contact potential difference of the semiconductor wafer surface relative to the non-vibrating contact potential difference sensor;

outputting the track data for the track to a computer system for determining whether the track was a last track;

assembling the contact potential difference track data for each scanned track to form representative contact potential difference track data representative of the semiconductor wafer surface;

processing the non-vibrating contact potential difference track data to automatically detect a pattern that represents a chemical defect or chemical non uniformity present on the semiconductor wafer surface and

outputting a large area spatial image, having a resolution of at least about 60 microns, of the semiconductor wafer surface, illustrating spatial location of the chemical defect or chemical non uniformity on the semiconductor wafer surface.

2. The method as defined in claim 1, further including the steps of:

displaying the contact potential difference data on a display to generate a characteristic wafer image; and

comparing the characteristic wafer image with standard images of chemical defects or chemical non uniformities to identify a category of the chemical defect of chemical non uniformity present on the surface of the semiconductor wafer.

3. The method as defined in claim 2 wherein the standard images of chemical defects or chemical non uniformities are selected from the group of a metal contaminated wafer image, an alcohol contaminated wafer image, a vacuum pick up damaged wafer image, a latex contaminated wafer image, and a human fingerprint contaminated wafer image.

4. The method as defined in claim 1, wherein the step of processing the sensor data includes assembling of the sensor data into an image that is displayed to the user for evaluation by the user.

5. The method as defined in claim 1 wherein the step of processing the sensor data includes automatically processing the sensor data to identify the category of defect or non uniformity detected.

6. The method as defined in claim 1 wherein the step of continuously radially scanning the semiconductor wafer comprises spinning the wafer.

7. The method as defined in claim 1 wherein the semiconductor wafer includes at least one additional layer disposed on a base silicon wafer.

8. A method of detecting the chemical cleanliness of a semiconductor wafer surface during an in-line processing of the semiconductor wafer, comprising the steps of:

providing an in-line semiconductor wafer processing system including a semiconductor wafer scanning system;

providing a semiconductor wafer having a surface;

positioning the semiconductor wafer in the semiconductor wafer scanning system;

positioning a non-vibrating contact potential difference sensor in operational relationship with the semiconductor wafer;

moving the non-vibrating contact potential difference sensor and the semiconductor wafer relative to each other in a scanning manner;

generating from the movement of the semiconductor wafer relative to the non-vibrating contact potential difference probe a signal output representative of the changes in contact potential between the non-vibrating contact potential difference sensor and the semiconductor wafer as the relative motion occurs thereby providing data representative of the changes in the contact potential difference across the semiconductor relative to the non-vibrating contact potential difference sensor;

processing the data to locate areas of high contact potential difference variability characteristic of changes in a chemical state of the semiconductor wafer; and

comparing the data to known contact potential difference data sets to determine whether the semiconductor wafer contains any chemical contaminants.

9. The method as defined in claim 8 wherein the step of processing comprises performing a pattern recognition methodology to determine a category of the chemical contaminants.

10. The method as defined in claim 9 further including the step of processing the wafer with a treatment for ameliorating the category of the chemical contaminants identified.

11. The method as defined in claim 8 further including the step of performing a supplementary analysis.

12. The method as defined in claim 11 wherein the step of performing a supplementary analysis includes analyzing chemical contaminants.

13. The method as defined in claim 8 further including the step of applying a computerized decisional methodology to reject selected ones of the semiconductor wafers having selected ones of the chemical contaminants.

14. A system for inline semiconductor wafer processing comprising:

a semiconductor wafer processing system to identify chemical contaminants or chemical non uniformities on a semiconductor wafer, the processing system including a wafer scanning system;

a semiconductor wafer;

a semiconductor wafer stage of the wafer scanning system for receiving the semiconductor wafer;

the semiconductor wafer stage which is rotatable and engageable with the semiconductor wafer;

a non-vibrating contact potential difference semiconductor sensor system having,

a non-vibrating contact potential difference probe;

a mechanism for securing the semiconductor wafer on the semiconductor wafer stage;

a positioning assembly in communication with the non-vibrating contact potential difference probe whereby the non-vibrating contact potential difference probe can be positioned relative to the semiconductor wafer secured on the semiconductor wafer stage;

the non-vibrating contact potential difference probe adapted to produce a signal characteristic of the chemical contaminants on the semiconductor wafer in response to a change in the contact potential difference generated by the relative motion of the non-vibrating contact potential difference probe and the semiconductor wafer;

a computer system in communication with the non-vibrating contact potential difference probe of the scanning system, whereby relative contact potential difference data is output by the probe to the computer;

a visual image characteristic of the chemical contaminants and their spatial distribution on the semiconductor wafer generated by the computer system and representative of the contact potential difference data.

15. The system as defined in claim 14 further including a data base of contact potential difference data for standard defects, the computer including computer software which can analyze the relative contact potential difference data and compare with the standard defect contact potential data to generate identification information about the type of defect and the spatial distribution present on the surface of the wafer.

16. The system as defined in claim 14 further including a transport device to move selected ones of the semiconductor wafers to a secondary processing system if the category of defect is one which can be remedied.

17. The system as defined in claim 14 further including a plurality of the sensors with one of the sensors disposed immediately downstream from each of a plurality of cleaning systems, thereby enabling monitoring of the semiconductor wafer after processed at each of the cleaning systems.

18. The system as defined in claim 14 that includes a mechanism for automatically determining the cleanliness of wafers and modifying cleaning parameters to improve the cleaning process.