Surface scanning

• US 7,397,553 B1
• Filed: 10/24/2005
• Issued: 07/08/2008
• Est. Priority Date: 10/24/2005
• Status: Active Grant

• Current Assignee: Kla-Tencor Technologies Corporation (KLA Corporation)
• Original Assignee: Kla-Tencor Technologies Corporation (KLA Corporation)
• Inventors: Meeks, Steven W., Rosengaus, Eliezer, Mehanian, Courosh
• Primary Examiner(s): Pham; Hoa Q
• Application Number:
  US11/257,234
• Time in Patent Office: 988 Days
• Field of Search: 3562371-2375, 356/239.8, 356/369, 250/559.41, 250/559.14
• US Class Current: 356/237.2
• CPC Class Codes: G01B 11/0641 with measurement of polarization
• CPC Class Codes: G01B 11/303 using photoelectric detection means
• CPC Class Codes: G01N 21/8851 Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges G01N21/8806 and G01N21/93 - G01N21/95692 take precedence; optical measurement of dimensions G01B11/00; optical scanning G02B26/10; image transformation G06T3/00; computerised image enhancement G06T5/00; image processing per se for flaw detection G06T7/0002
• CPC Class Codes: G01N 21/9501 Semiconductor wafers manufacturing processes per se of semiconductor devices implementing a measuring step H01L22/10

Abstract

In one embodiment, a surface scanning system comprises a radiation directing assembly that scans a surface using a Cartesian scanning pattern; and a radiation collecting assembly that collects radiation reflected from the surface. A scattered radiation collection system is included that measures the scattered light from the surface.

Claims

1. A surface scanning system, comprising:

a radiation directing assembly to scan a surface using a Cartesian scanning pattern; and

a radiation collecting assembly that collects radiation reflected from the surface, the radiation collecting assembly comprising;

a quarter-wave plate; and

a polarizing beam splitter oriented at an oblique angle relative to the plane of incidence, such that a portion of the radiation reflected from the surface is split into a first mixed component and a second mixed component, each mixed component comprising both P-polarized and S-polarized radiation.

2. The system of claim 1, wherein:

the radiation directing assembly directs at a constant azimuth angle.

3. The system of claim 1, wherein the radiation directing assembly comprises:

a radiation source;

a rotating polygonal mirror that reflects radiation from the radiation source;

a parabolic mirror to reflect radiation from the rotating polygonal mirror onto the surface.

4. The system of claim 3, wherein the radiation collecting assembly comprises a planar mirror to direct radiation reflected from the surface onto the surface of the parabolic mirror.

5. The system of claim 1, wherein the radiation collecting assembly includes one or more transparent sheets of material that transmit radiation reflected from the surface to a radiation detector.

6. The system of claim 1, further comprising a scan lens that focuses radiation from the radiation source onto the surface.

7. The system of claim 1, wherein the radiation collecting assembly comprises:

a first radiation collecting assembly to collect radiation specularly reflected from the surface; and

a second radiation collecting assembly to collect radiation scattered from the surface.

8. The system of claim 7, wherein the second radiation collecting assembly comprises a Fresnel lens.

9. The system of claim 7, further comprising:

a processor coupled to the first radiation collecting assembly;

a memory module coupled to the processor and comprising logic instructions which, when executed by the processor, configure the processor to;

generate a first signal from radiation reflected from the surface; and

use the first signal to determine a characteristic of the surface.

10. A surface analysis method, comprising:

scanning a radiation beam across a surface along a Cartesian scanning path;

collecting radiation reflected from the surface, and radiation scattered from the surface, wherein collecting radiation comprises a splitting a portion of the radiation with a polarizing beam splitter oriented at an oblique angle relative to the plane of incidence, such that a portion of the radiation reflected from the surface is split into a first mixed component and a second mixed component, each mixed component comprising both P-polarized and S-polarized radiation;

and

using at least one of the radiation reflected from the surface or the radiation scattered from the surface to detect profile variations in the surface.

11. The method of claim 10, wherein scanning a radiation beam across a surface along a Cartesian scanning path comprises impinging radiation on the surface at a constant azimuth angle.

12. The method of claim 10, wherein scanning a radiation beam across a surface along a Cartesian scanning path comprises traversing the radiation beam across the surface in a serpentine pattern.

13. The method of claim 10, wherein scanning a radiation beam across a surface along a Cartesian scanning path comprises reflecting the radiation beam from a rotating mirror onto a parabolic mirror.

14. The method of claim 10, wherein scanning a radiation beam across a surface along a Cartesian scanning path comprises reflecting radiation from a rotating mirror onto a scan lens.

15. The method of claim 10, wherein collecting radiation reflected from the surface comprises splitting the reflected radiation into a first radiation beam having a first polarization and a second radiation beam having a second polarization.