Massively parallel inspection and imaging system

• US 6,208,411 B1
• Filed: 09/28/1998
• Issued: 03/27/2001
• Est. Priority Date: 09/28/1998
• Status: Expired due to Term

• Current Assignee: KLA-Tencor Corporation (KLA Corporation)
• Original Assignee: KLA-Tencor Corporation (KLA Corporation)
• Inventors: Vaez-Iravani, Mehdi
• Primary Examiner(s): Rosenberger, Richard A.
• Application Number:
  US09/161,864
• Time in Patent Office: 911 Days
• Field of Search: 356/354, 356/237.4, 356/237.5, 356/376, 356/237.2, 356/237.3
• US Class Current: 356/237.2
• CPC Class Codes: G01N 2021/8905 Directional selective optics, e.g. slits, spatial filters
• CPC Class Codes: G01N 21/8806 Specially adapted optical and illumination features
• CPC Class Codes: G01N 21/9501 Semiconductor wafers manufacturing processes per se of semiconductor devices implementing a measuring step H01L22/10
• CPC Class Codes: G01N 21/956 Inspecting patterns on the surface of objects contactless testing of electronic circuits G01R31/308; testing currency G07D; manufacturing processes per se of semiconductor devices implementing a measuring step H01L22/10

Abstract

A massively parallel inspection and imaging system is provided which employs multiple focused beams to illuminate a specimen. Laser light energy passes through a relatively low resolution diffraction grating or digital optical element, which is either one or two dimensional, and concentrates the transmitted energy into multiple discrete directions or orders. The beams split by the diffraction grating pass through a beam expander or telescope and are recombined onto an optical element and diverted toward the specimen. On reflection toward the specimen, the beams diverge again toward a focusing objective. The resultant light thus comprises multiple focused beams, and a relatively large area of the specimen is illuminated simultaneously by these beams. Upon reflection of the light from the sample, light passes back through the focusing objective in multiple beams, and the beams converge toward the optical element and diverge outward in collimated beams. The collimated beams pass through a focusing lens, which brings all beams onto foci on a detector array. Scanning of patterned wafers by the system may occur using coordinated motion of both the scanning beam and the wafer. To achieve proper orientation and observation, the stage speed in the cross direction is set at the ratio of the distance between the first and last lines divided by the period of the scanner.

Claims

1. A system for inspecting a specimen, comprising:

a light generating device;

a diffractive element receiving light energy transmitted by said light generating device;

a telescopic lensing arrangement receiving light energy transmitted by said diffractive element;

a beamsplitter for splitting light received from said telescopic lensing arrangement;

an objective receiving light energy from said beamsplitter;

a focusing lens receiving light energy from said objective, said focusing lens having a focal plane and an apparent plane of splitting of light, wherein the focusing lens focal plane substantially coincides with the apparent plane of splitting of light; and

a detector arrangement;

wherein said diffractive element splits light energy received from said light generating device thereby providing multiple light beams, and wherein multiple light beams contact said specimen.

2. The system of claim 1, wherein said diffractive element comprises a diffractive element from the group including a one dimensional grating and a two dimensional grating.

3. The system of claim 1, wherein said detector arrangement comprises a detector from the group comprising a CCD detector, a photodiode array, and a multiple PMT array.

4. The system of claim 1, wherein inspection comprises linear scanning.

5. The system of claim 1, wherein said diffractive element comprises an optical element from the group including a diffraction grating and a digital optical element.

6. A system for inspecting a specimen, comprising:

a light generating device;

a diffractive element receiving light energy transmitted by said light generating device;

a telescopic lensing arrangement receiving light energy transmitted by said diffractive element;

a beamsplitter for splitting light received from said telescopic lensing arrangement;

an objective receiving light energy from said beamsplitter;

a focusing lens receiving light energy from said objective, and

a detector arrangement;

wherein said diffractive element splits light energy received from said light generating device thereby providing multiple light beams, and wherein multiple light beams contact said specimen, and wherein light energy passes from said diffractive element through said telescopic lensing arrangement and subsequently contacts said beamsplitter and passes through said objective and is imparted in multiple beams onto said specimen.

7. The system of claim 6, wherein light energy further passes from said sample through said objective and said beamsplitter and through said focusing lens onto said detector arrangement.

8. A method for inspecting a specimen, comprising the steps of:

splitting light provided by a light generating source into a first plurality of beams,

telescopically recombining said first plurality of beams;

optically arranging said recombined beams such that a second plurality of beams are applied to said specimen using a focusing lens having a focal plane that substantially coincides with the apparent plane of splitting of light; and

receiving multiple images of said specimen;

wherein said arranging step comprises;

telescoping said beams;

converging said beams toward an optical element;

reflecting said beams from said optical element; and

refining said beams through an objective.

9. The method of claim 8, wherein said optical element comprises an optical element from a group comprising a beamsplitter and a reflector.

10. The method of claim 8, wherein said arranging step further comprises:

passing multiple beams from said specimen through said objective;

passing said beams to said optical element; and

focusing said beams.

11. The method of claim 10, wherein said second passing step comprises one step from the group of:

(a) passing said beams through a beamsplitter; and

(b) reflecting said beams off a reflector.

12. A method for inspecting a specimen, comprising the steps of:

splitting light provided by a light generating source into a first plurality of beams;

telescopically recombining said first plurality of beams;

optically arranging said recombined beams such that a second plurality of beams are applied to said specimen using a focusing lens having a focal plane that substantially coincides with the apparent plane of splitting of light; and

receiving multiple images of said specimen;

wherein said splitting step comprises passing light received from said light generating source through a diffractive element.

13. A method for inspecting a specimen having multiple orthogonal paths located thereon, said inspection method including using an observation process, comprising the steps of:

applying a plurality of observation beams onto said specimen;

orienting said specimen at a first substantially nonparallel angle with respect to said multiple orthogonal paths;

positioning said specimen at a second substantially nonparallel angle with respect to a linear advancing of said observation beams;

wherein said linear advancing of said observation beams is substantially orthogonal to said passing of specimen linearly,

passing said oriented and positioned specimen linearly at an angle substantially parallel to said first substantially nonparallel angle; and

linearly advancing said observation beams in an orientation orthogonal to said passing of said oriented and positioned specimen,

wherein said passing step occurs simultaneously with said linearly advancing step.

14. The method of claim 13, wherein said linearly advancing step is performed in a direction offset from the orientation of said orthogonal angle.

15. The method of claim 13, wherein said first substantially nonparallel angle is a function of specimen passing rate and beams advance rate.

16. The method of claim 13, wherein said specimen comprises a semiconductor wafer and said paths comprise rows of orthogonal wiring located thereon.

17. A device for inspecting a specimen, comprising:

a light emitting source;

a light splitting arrangement, wherein said light splitting arrangement divides light received from said light emitting source into multiple beams; and

a lensing arrangement for imparting a plurality of beams to said specimen, comprising;

combining optics for recombining said multiple beams received from said light splitting arrangement; and

a focusing lens having a focal plane and apparent plane of splitting of light, wherein the focusing lens focal plane substantially coincides with the apparent plane of splitting of light and receiving light energy from said combining optics;

wherein said light splitting arrangement comprises one from the group of;

(a) a diffraction grating; and

(b) a digital optical element.

18. A device for inspecting a specimen, comprising:

a light emitting source;

a light splitting arrangement, wherein said light splitting arrangement divides light received from said light emitting source into multiple beams;

a lensing arrangement for imparting a plurality of beams to said specimen, comprising;

combining optics for recombining said multiple beams received from said light splitting arrangement; and

a focusing lens having a focal plane and apparent plane of splitting of light, wherein the focusing lens focal plane substantially coincides with the apparent plane of splitting of light and receiving light energy from said combining optics;

wherein said lensing arrangement comprises;

a telescoping lens group;

a beamsplitting element; and

an objective;

wherein light energy passes from said light splitting arrangement through said telescoping lens group and subsequently contacts said beamsplitter, passes through said objective and is imparted in multiple beams onto said sample.