Wafer surface inspection method

• US 6,724,474 B1
• Filed: 09/28/2000
• Issued: 04/20/2004
• Est. Priority Date: 09/30/1999
• Status: Expired due to Fees

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Cho, Kyoo-chul, Heo, Tae-yeol, Kang, Kyong-rim, Choi, Soo-yeul
• Primary Examiner(s): Rosenberger, Richard A.
• Assistant Examiner(s): Barth, Vincent P.
• Application Number:
  US09/670,817
• Time in Patent Office: 1,300 Days
• Field of Search: 356/335, 356/336, 356/338, 356/343, 356/237.1, 356/237--23, 250/559.44
• US Class Current: 356/237.4
• CPC Class Codes: G01N 2021/8822 Dark field detection
• CPC Class Codes: G01N 21/94 Investigating contamination, e.g. dust G01N21/85 takes precedence
• CPC Class Codes: G01N 21/9501 Semiconductor wafers manufacturing processes per se of semiconductor devices implementing a measuring step H01L22/10
• CPC Class Codes: H01L 21/3065 Plasma etching; Reactive-ion etching
• CPC Class Codes: H01L 22/12 for structural parameters, e.g. thickness, line width, refractive index, temperature, warp, bond strength, defects, optical inspection, electrical measurement of structural dimensions, metallurgic measurement of diffusions electrical measurement of diffusions H01L22/14

Abstract

Types of defects on a wafer are discriminated according to defect measurements obtained from a wafer inspection system which includes a plurality of dark field detectors. Using the wafer measurement system, it is determined whether first, second and third conditions are satisfied. The first condition is when a size of a defect on the wafer measured by the wafer inspection system is smaller than a limit value denoting a maximum size of crystal originated particles. The second condition is when a correlation between a plurality of defect light intensity values detected by a plurality of dark field detectors of the wafer measurement system satisfies a reference value. The third condition is when a location of the defect measured by the wafer inspection system is within a vacancy-rich area of the wafer. The type of the defect is then determined to be a crystal originated particle when the first, second and third conditions are all satisfied. On the other hand, the type of defect is determined to be an actual particle when any one or more of the first, second and third conditions is not satisfied.

Claims

1. A wafer surface inspection method for discriminating among types of defects on a wafer according to defect measurements obtained from a wafer inspection system which includes a plurality of dark field detectors, said method comprising:

determining whether a first condition is satisfied in which a size of a defect on the wafer measured by the wafer inspection system is smaller than a limit value denoting a maximum size of crystal originated particles;

determining whether a second condition is satisfied in which a correlation between a plurality of defect light intensity values detected by the plurality of dark field detectors satisfies a reference value;

determining whether a third condition is satisfied in which a location of the defect measured by the wafer inspection system is within a vacancy-rich area of the wafer; and

determining that the type of the defect is a crystal originated particle when the first, second and third conditions are all satisfied, and determining that the type of defect is an actual particle when any one or more of the first, second and third conditions is not satisfied.

2. The wafer surface inspection method of claim 1, wherein the limit value is 0.16 μ

m.

3. The wafer surface inspection method of claim 1, wherein a scatterometric particle measurement system is used as the wafer inspection system.

4. The wafer surface inspection method of claim 3, wherein each of the dark field detectors comprises a wide angle photo-multiplier tube for detecting light scattered from the defect at a wide angle and a narrow angle photo-multiplier tube for detecting light scattered from the defect at a narrow angle.

5. The wafer surface inspection method of claim 4, wherein the plurality of defect light intensity values include a defect intensity value S_W obtained from the wide angle photo-multiplier tube and a defect intensity value S_N obtained from the narrow angle photo-multiplier tube, and wherein the second condition is where an intensity ratio S_N/S_W of the intensity value S_N to the intensity value S_W exceeds the reference value.

6. The wafer surface inspection method of claim 3, wherein each of the dark field detectors comprises a small angle detector for detecting light components scattered forward from the defect at a small angle, a medium angle detector for detecting light components scattered perpendicularly from the defect at a medium angle and a large angle detector for detecting light components scattered backwardly from the defect at a large angle.

7. The wafer surface inspection method of claim 6, wherein the plurality of defect light intensity values include a defect light intensity value S_S obtained from the small angle detector, a defect light intensity value S_M obtained from the medium angle detector and a defect light intensity value S_L obtained from the large angle detector, and wherein the second condition is where both (a) an intensity ratio S_M/S_L of the intensity value S_M to the intensity value S_L exceeds a first reference value and (b) an intensity ratio S_M/S_S of the intensity value S_M to the intensity value S_S exceeds a second reference value.

8. A wafer surface inspection method for discriminating among types of defects on a wafer, said method comprising:

using a wafer inspection system to measure a size of a defect on the wafer;

determining whether a first condition is satisfied in which a size of the defect on the wafer is smaller than a limit value denoting a maximum size of crystal originated particles;

using a plurality of dark field detectors of the wafer inspection system to respectively detect a plurality of defect light intensity values of the defect;

determining whether a second condition is satisfied in which a correlation between the plurality of defect light intensity values satisfies a reference value;

using the wafer inspection system to determine a location of the defect;

determining whether a third condition is satisfied in which the location of the defect is within a vacancy-rich area of the wafer; and

determining that the type of the defect is a crystal originated particle when the first, second and third conditions are all satisfied, and determining that the type of defect is an actual particle when any one or more of the first, second and third conditions is not satisfied.

9. The wafer surface inspection method of claim 8, wherein the limit value is 0.16 μ

m.

10. The wafer surface inspection method of claim 8, wherein a scatterometric particle measurement system is used as the wafer inspection system.

11. The wafer surface inspection method of claim 10, wherein each of the dark field detectors comprises a wide angle photo-multiplier tube for detecting light scattered from the defect at a wide angle and a narrow angle photo-multiplier tube for detecting light scattered from the defect at a narrow angle.

12. The wafer surface inspection method of claim 11, wherein the plurality of defect light intensity values include a defect intensity value S_W obtained from the wide angle photo-multiplier tube and a defect intensity value S_N obtained from the narrow angle photo-multiplier tube, and wherein the second condition is where an intensity ratio S_N/S_W of the intensity value S_N to the intensity value S_W exceeds the reference value.

13. The wafer surface inspection method of claim 10, wherein each of the dark field detectors comprises a small angle detector for detecting light components scattered forward from the defect at a small angle, a medium angle detector for detecting light components scattered perpendicularly from the defect at a medium angle and a large angle detector for detecting light components scattered backwardly from the defect at a large angle.

14. The wafer surface inspection method of claim 13, wherein the plurality of defect light intensity values include a defect light intensity value S_S obtained from the small angle detector, a defect light intensity value S_M obtained from the medium angle detector and a defect light intensity value S_L obtained from the large angle detector, and wherein the second condition is where both (a) an intensity ratio S_M/S_L of the intensity value S_M to the intensity value S_L exceeds a first reference value and (b) an intensity ratio S_M/S_S of the intensity value S_M to the intensity value S_S exceeds a second reference value.