Method of determining the doping concentration and defect profile across a surface of a processed semiconductor material

• US 6,320,403 B1
• Filed: 08/10/1998
• Issued: 11/20/2001
• Est. Priority Date: 08/10/1998
• Status: Expired due to Fees

• Current Assignee: Advanced Micro Devices, Inc.
• Original Assignee: Advanced Micro Devices, Inc.
• Inventors: Tsui, Ting Yiu, Liu, Yowjuang William, Shabde, Sunil N.
• Primary Examiner(s): Metjahic, Safet
• Assistant Examiner(s): Hollington, Jermele M.
• Application Number:
  US09/131,588
• Time in Patent Office: 1,198 Days
• Field of Search: 324/766, 324/765, 324/762, 324/158.1, 324/719, 324/758, 324/724, 324/252
• US Class Current: 324/754.27
• CPC Class Codes: G01R 31/2648 Characterising semiconductor materials testing of materials or semi-finished products G01R31/2831; testing during manufacture H01L22/00
• CPC Class Codes: Y10S 977/854 Semiconductor sample

Abstract

A method (100) of determining a doping type and a doping concentration of a semiconductor material (101) includes the steps of moving carriers (103) in the material, wherein a number of carriers is a function of the doping concentration of the material (101) and a type of carriers is a function of the doping type of the material (101). The carriers are deflected (130) toward a surface (110) of the material (101) and an accumulated charge profile on the surface of the material, due to the deflected carriers, is detected (140) and used to calculate (180) the doping concentration across a surface (110) of the material (101).

Claims

1. A method of determining a doping type and a doping concentration of a processed semiconductor material, comprising the steps of:

moving carriers in the material, wherein a number of carriers is a function of the doping concentration of the material and a type of carriers is a function of the doping type of the material;

deflecting the carriers toward a surface of the material; and

detecting an accumulated charge on the surface of the material due to the deflected carriers.

2. The method of claim 1, wherein moving carriers comprises forcing a current in the material.

3. The method of claim 1, further comprising determining the doping type based on a polarity of the accumulated charge.

4. The method of claim 1, wherein detecting an accumulated charge comprises:

(a) initializing a scanning coordinate of a detection apparatus;

(b) detecting a charge amount at a first point on the material surface;

(c) moving the detection apparatus to another point on the material surface;

(d) detecting the charge amount at the other point; and

(e) repeating steps (c) and (d) until the surface of the material is substantially scanned and an accumulated charge profile is detected.

5. The method of claim 1, wherein detecting an accumulated charge comprises:

(a) initializing a scanning coordinate for a charge detector;

(b) scanning a first row in a first direction and detecting the accumulated charge at a plurality of points in the first row with the charge detector;

(c) moving the charge detector in a direction perpendicular to the first row to a next row;

(d) scanning the next row in the first direction and detecting the accumulated charge at a plurality of points in the next row with the charge detector;

(e) repeating steps (c) and (d) until the surface of the material is substantially scanned and an accumulated charge profile is detected.

6. The method of claim 1, wherein detecting an accumulated charge comprises:

(a) initializing a scanning coordinate for an atomic force microscope tip;

(b) placing the atomic force microscope tip at the initialized coordinate near the surface;

(c) detecting a charge amount at the initialized point on the material surface;

(d) moving the atomic microscope tip in a first direction to another point near the material surface;

(e) detecting the charge amount at the other point;

(f) repeating steps (d) and (e) until the atomic force microscope tip has scanned a predetermined number of points in the first direction, thereby scanning a row;

(g) moving the tip in a second direction substantially perpendicular to the first direction to another row;

(h) detecting a charge amount at the point of the atomic force microscope tip location;

(i) repeating steps (d) and (e) until the atomic force microscope tip has scanned the predetermined number of points in the first direction, thereby scanning another row; and

(j) repeating steps (g), (h) and (i) until the atomic force microscope has scanned substantially the entire surface of the material.

7. The method of claim 1, further comprising calculating the doping concentration at a point on the material surface using the detected accumulated charge at the point on the material surface.

8. The method of claim 7, further comprising:

scanning the surface of the material; and

calculating the doping concentration at each point on the scanned material surface using the detected accumulated charge at each respective point on the material surface.

9. The method of claim 1, wherein deflecting the carriers comprises subjecting the material to a magnetic field.

10. The method of claim 9, wherein a direction of the magnetic field is perpendicular to a direction of flow of the carriers, wherein the magnetic field exerts a force on the carriers due to a Hall effect.

11. The method of claim 9, wherein the magnetic field comprises a generally static magnetic field.

12. The method of claim 1, wherein detecting the accumulated charge on the material surface comprises:

placing a probe at a point near the material surface; and

measuring a voltage at the point.

13. The method of claim 12, wherein the probe is an atomic force microscope tip.

14. The method of claim 13, wherein measuring the voltage with the tip comprises detecting an amount of deflection of the tip due to an electrostatic force exerted on the tip by the accumulated charge.

15. The method of claim 13, wherein measuring the voltage with the tip comprises detecting an amount of variation in a vibrating frequency of the tip due to an electrostatic force exerted on the tip by the accumulated charge.