Laser-Assisted Electron-Beam Inspection for Semiconductor Devices

• US 20190333733A1
• Filed: 08/27/2018
• Published: 10/31/2019
• Est. Priority Date: 04/27/2018
• Status: Active Grant

• Current Assignee: Zhongke Jingyuan Electron Limited
• Original Assignee: Zhongke Jingyuan Electron Limited
• Inventors: Li, Shiguang, Zhao, Yan, Guo, Jie, Zong, Mingcheng
• Granted Patent: US 10,553,393 B2
• Time in Patent Office: Days
• CPC Class Codes: G02B 27/0955 Lenses lenses per se G02B3/00
• CPC Class Codes: G02B 27/0961 Lens arrays lens arrays per se G02B3/0006
• CPC Class Codes: G02B 27/0966 Cylindrical lenses cylindrical lenses per se G02B3/06
• CPC Class Codes: G02B 27/30 Collimators
• CPC Class Codes: G02B 5/122 cube corner, trihedral or triple reflector type
• CPC Class Codes: H01J 2237/24475 Scattered electron detectors
• CPC Class Codes: H01J 2237/2448 Secondary particle detectors
• CPC Class Codes: H01J 2237/24592 Inspection and quality control of devices
• CPC Class Codes: H01J 2237/2817 Pattern inspection
• CPC Class Codes: H01J 37/147 Arrangements for directing or deflecting the discharge along a desired path H01J37/045 take precedence; lenses H01J37/10
• CPC Class Codes: H01J 37/226 Optical arrangements for illuminating the object; optical arrangements for collecting light from the object
• CPC Class Codes: H01J 37/228 whereby illumination and light collection take place in the same area of the discharge
• CPC Class Codes: H01J 37/244 Detectors; Associated components or circuits therefor
• CPC Class Codes: H01J 37/265 Controlling the tube; circuit arrangements adapted to a particular application not otherwise provided, e.g. bright-field-dark-field illumination
• 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
• CPC Class Codes: H01L 27/0924 including transistors with a horizontal current flow in a vertical sidewall of a semiconductor body, e.g. FinFET, MuGFET

Abstract

Methods and apparatuses for laser-assisted electron-beam inspection (EBI) are provided. The apparatus includes an EBI device and a laser illumination device. The EBI device includes an e-beam source configured to emit an incident e-beam, a deflector configured to deflect the incident e-beam to be projected onto a surface of a semiconductor device, and an electron detector configured to detect emergent electrons generated by the incident e-beam projected onto the surface. The laser illumination device includes a laser source configured to generate a laser, and a guiding device configured to guide the laser to be projected onto the semiconductor device. The laser changes the emergent electrons to cause, in a positive mode of the EBI apparatus, a PN junction of an NMOS of the semiconductor device to be in a conduction state.

Claims

1. An apparatus for laser-assisted electron-beam inspection, comprising:

an electron-beam (e-beam) inspection device, comprising;

an e-beam source, configured to emit an incident e-beam;

a deflector, configured to deflect the incident e-beam to be projected onto a surface of a semiconductor device; and

an electron detector, configured to detect emergent electrons generated by the incident e-beam projected onto the surface; and

a laser illumination device, comprising;

a laser source, configured to generate a laser; and

a guiding device, configured to guide the laser to be projected onto the semiconductor device, wherein the laser changes the emergent electrons by a photovoltaic effect to cause, in a positive mode of the EBI apparatus, a PN junction of an N-type metal-oxide semiconductor (NMOS) of the semiconductor device to be in a conduction state.

2. The apparatus of claim 1, wherein the guiding device comprises:

a beam shaper, configured to shape the laser as a shaped laser to form a laser spot, wherein the laser spot is uniform and in a predetermined shape; and

a first reflector, arranged downstream the beam shaper and configured to reflect the shaped laser to the surface in a predetermined range of angles.

3. The apparatus of claim 2, wherein the guiding device further comprises:

an optical retroreflector, configured to retroreflect an emergent laser from the surface to form a retroreflected laser; and

a second reflector, arranged between the surface and the optical retroreflector, and configured to reflect the emergent laser toward the optical retroreflector, and reflect the retroreflected laser toward the surface.

4. The apparatus of claim 3, wherein the optical retroreflector comprises:

a pyramid prism; and

a second lens, arranged between the second reflector and the pyramid prism, wherein

the pyramid prism is configured to change a position and an incident angle of the emergent laser reflected off the second reflector through the second lens to retroreflect the emergent laser through the second lens back to the second reflector; and

the second lens is configured to converge the emergent laser reflected off the second reflector toward the pyramid prism.

5. The apparatus of claim 4, wherein the pyramid prism is shaped to be symmetrical about an optical axis of the pyramid prism and arranged to be coaxial with the second lens, and the pyramid prism is configured to retroreflect, symmetrically about the optical axis of the pyramid prism, the emergent laser reflected off the second reflector back to the second reflector.

6. The apparatus of claim 3, wherein the optical retroreflector comprises:

a hollow corner cube made by a mirror group; and

a second lens, arranged between the second reflector and the hollow corner cube, wherein

the hollow corner cube is configured to change a position and an incident angle of the emergent laser reflected off the second reflector through the second lens to retroreflect the emergent laser through the second lens back to the second reflector; and

the second lens is configured to converge the emergent laser reflected off the second reflector toward the hollow corner cube.

7. The apparatus of claim 2, wherein the beam shaper comprises:

a first microlens array configured to uniformize the laser, comprising multiple microlenses arranged in a plane orthogonal to an optical axis of the laser.

8. The apparatus of claim 7, wherein the beam shaper further comprises:

a second microlens array, comprising multiple microlenses arranged in the plane orthogonal to the optical axis of the laser, arranged downstream the first microlens array, and configured to function as a field lens.

9. The apparatus of claim 8, wherein the beam shaper further comprises:

a first lens, arranged between the second microlens array and the first reflector, and configured to converge the shaped laser toward the test surface.

10. The apparatus of claim 9, wherein the guiding device further comprises:

a scattering piece, arranged between the second microlens array and the first lens.

11. The apparatus of claim 8, wherein the first lens is a Fourier lens configured to change the laser spot to be of a predetermined size on a rear focal plane of the Fourier lens.

12. The apparatus of claim 7, wherein the beam shaper comprises:

a collimating lens configured to collimate the laser, arranged between the laser source and the first microlens array.

13. The apparatus of claim 2, wherein the beam shaper comprises:

a pair of cylindrical lenses, arranged coaxially and configured to uniformize the laser.

14. The apparatus of claim 13, wherein the pair of cylindrical lenses are orthogonal.

15. The apparatus of claim 14, wherein the beam shaper further comprises:

a first lens, arranged between the pair of cylindrical lenses and the first reflector, and configured to converge the shaped laser toward the test surface.

16. The apparatus of claim 15, wherein the guiding device further comprises:

a scattering piece, arranged between the pair of cylindrical lenses and the first lens.

17. The apparatus of claim 2, wherein the beam shaper comprises at least one of a light-uniformizing plate and a compound-eye lens.

18. The apparatus of claim 1, wherein the laser is projected onto the surface.

19. The apparatus of claim 1, wherein the emergent electrons comprise at least one of secondary electrons and backscattered electrons, wherein the secondary electrons and the backscattered electrons are generated by the incident e-beam projected onto the surface.

20. A method for laser-assisted electron-beam inspection, comprising:

detecting, using an apparatus in a simultaneous manner, whether an open-circuit defect exist in a metal contact hole corresponding to a P-type metal-oxide semiconductor (PMOS) of a semiconductor device or a metal contact hole corresponding to an N-type metal-oxide semiconductor (NMOS) of the semiconductor device, wherein the apparatus comprises an electron detector and the EBI apparatus is in a positive mode, and the apparatus further comprises

an electron-beam (e-beam) inspection device, comprising;

an e-beam source, configured to emit an incident e-beam;

a deflector, configured to deflect the incident e-beam to be projected to a surface of the semiconductor device; and

the electron detector, configured to detect emergent electrons generated by the incident e-beam projected onto the surface; and

a laser illumination device, comprising;

a laser source, configured to generate a laser; and

a guiding device, configured to guide the laser to be projected to the semiconductor device, wherein the laser changes the emergent electrons to cause a PN junction of the NMOS to be in a conduction state.