Method and apparatus for inspection of patterned semiconductor wafers

• US 6,317,514 B1
• Filed: 09/09/1998
• Issued: 11/13/2001
• Est. Priority Date: 09/09/1998
• Status: Expired due to Term

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Almogy, Gilad, Reinhorn, Silviu
• Primary Examiner(s): Bella, Matthew C.
• Assistant Examiner(s): CHAWAN, SHEELA C
• Application Number:
  US09/150,296
• Time in Patent Office: 1,161 Days
• Field of Search: 382/143, 382/145, 382/147, 382/318, 382/149, 250/224, 250/225, 250/305, 250/306, 250/310, 250/396.R, 250/492.2, 250/559.45, 250/358.1, 348/126, 348/128, 348/131, 378/143
• US Class Current: 382/147
• CPC Class Codes: G01N 21/95692 Patterns showing hole parts, e.g. honeycomb filtering structures
• 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

Novel method and apparatus are disclosed for inspecting a wafer surface to detect the presence thereon of exposed conductive material, particularly for determining the integrity of contact holes and vias, in semiconductor wafer manufacturing. The method comprises the steps of irradiating a spot of the wafer surface with a beam having a wavelength sufficiently shorter than the working function of the metal, such as deep UV light beam, collecting the electrons released by the irradiated wafer, generating an electrical signal that is a function of the collected electrons, and inspecting the signal to determine whether the contact holes or vias within the irradiated wafer spot are open. The apparatus comprises a vacuum chamber having therein a stage and chuck for supporting the wafer. An illumination source generates irradiating energy which is formed into a beam using appropriate optics so as to obtain the desired beam spot of the wafer'"'"'s surface. an electron detector collects electrons released from the wafer surface and sends a corresponding signal to a processor for processing the signal to determine whether the metal at the bottom of the hole is exposed. Optionally, the light scattered by the wafer is detected by detectors arranged around the illuminating beam.

Claims

1. A method of detecting defects on a wafer surface, wherein the defect detection is based on classifying a surface material, the method comprising the steps of:

(a) generating an illumination beam;

(b) impinging said illumination beam upon the wafer surface to release electrons therefrom;

(c) collecting the electrons emitted from the wafer surface due to the impingement of said beam;

(d) generating a signal corresponding to the amount of electrons collected from the wafer in step (c);

(e) analyzing the signal generated in step (d) to determine the presence of defects on the wafer based on the material classification.

2. The method according to claim 1, wherein the step of generating an illumination beam comprises generating a deep UV light beam.

3. The method according to claim 1, wherein the analyzing step comprises comparing the signal to a reference signal chosen from among a database signal and a corresponding signal produced from adjacent die or cell.

4. The method according to claim 1, wherein the step of analyzing comprises using the signal to determine the working function of inspected material on the substrate.

13. The method according to claim 1, wherein metal defects are detected on the wafer surface.

14. The method according to claim 1, wherein the wafer surface includes high aspect ratio structures.

15. The method according to claim 1, further comprising the step of:

(f) moving the wafer to a review tool for further investigation when the defect is detected.

16. The method according to claim 1, wherein the defect detection based is performed in real-time.

5. A method of determining the presence of exposed metal on a semiconductor wafer based on classifying a surface material, comprising the steps of:

(a) producing an illumination beam;

(b) irradiating a spot on the wafer surface with the illumination beam to release electrons therefrom;

(c) collecting electrons released from the wafer surface by the illumination beam;

(d) generating an electrical signal that is a function of the collected electrons in step (c); and

,

(e) using the signal generated in step (d) to determine whether an exposed metal is present within the illuminated spot based on the material classification.

6. The method according to claim 5, wherein the step of generating an illumination beam comprises generating a deep UV light beam.

7. The method according to claim 5, wherein the step of using the signal to determine whether an exposed metal is present within the illuminated spot comprises comparing the signal to a reference signal chosen from among a database signal and a corresponding signal produced from adjacent die or cell.

8. The method according to claim 5, wherein the step of using the signal to determine whether an exposed metal is present within the illuminated spot comprises using the signal to determine the working function of inspected material on the substrate.

17. The method according to claim 5, wherein the semiconductor wafer surface includes high aspect ratio structures.

18. The method according to claim 5, further comprising the step of:

(f) moving the wafer to a review tool for further investigation when exposed metal is detected.

19. The method according to claim 5, wherein the defect detection based is performed in real-time.

9. An apparatus for inspection of substrates, comprising:

a substrate support in a vacuum chamber;

a source of radiation generating an irradiating beam;

an optical system directing the beam to produce a desired illumination pattern on the substrate;

electron sensor positioned to collect electrons released from the wafer surface;

a processor receiving a signal obtained from said sensor to determine whether conductive matter is present within said illumination pattern based on classification of a surface material.

10. The apparatus according to claim 9, further comprising an electrode mounted above the substrate and held at a positive potential with respect to the wafer.

11. The apparatus according to claim 9, further comprising light detectors arranged around the irradiating beam for detecting light scattered from the illuminated substrate.

12. The apparatus according to claim 10, further comprising light detectors arranged around the irradiating beam for detecting light scattered from the illuminated substrate.