Objective lens

Patent metadata

Field	Value
Publication number	US-10598607-B2
Application number	US-201815881777-A
Country	US
Kind code	B2
Filing date	Jan 28, 2018
Priority date	Jun 14, 2017
Publication date	Mar 24, 2020
Grant date	Mar 24, 2020

Abstract

An inspection system for inspecting a semiconductor substrate, the inspection system may include an inspection unit that comprises a partially blocking bright field unit and a non-blocking bright field unit; wherein the partially blocking bright field unit is configured to block any specular reflection that fulfills the following: (a) the specular reflection is caused by illuminating, along a first axis, of an area of the wafer, (b) the specular reflection propagates along a second axis, (c) the first axis and the second axis are symmetrical about a normal to the area of the wafer, and (d) the normal is parallel to an optical axis of the partially blocking bright field unit; and wherein the non-blocking bright field unit is configured to pass to the image plane any specular reflection that fulfills the following: (a) the specular reflection is caused by illuminating, along the first axis, of an area of the wafer, (b) the specular reflection propagates along the second axis, (c) the first axis and the second axis are symmetrical about the normal, and (d) the normal is parallel to the optical axis of the partially blocking bright field unit.

First claim

We claim:

1. An inspection system for inspecting a semiconductor substrate, that comprises:
an inspection unit that comprises a partially blocking bright field unit and a non-blocking bright field unit;
wherein the partially blocking bright field unit is configured to (i) block any specular reflection that fulfills the following: (a) the specular reflection is caused by illuminating, along a first axis, of an area of the wafer, (b) the specular reflection propagates along a second axis, (c) the first axis and the second axis are symmetrical about a normal to the area of the wafer, and (d) the normal is parallel to an optical axis of the partially blocking bright field unit; and to (ii) allow transmission, through the partially blocking bright field unit, of some other specular reflected beams; and
wherein the non-blocking bright field unit is configured to pass to the image plane any specular reflection that fulfills the following: (a) the specular reflection is caused by illuminating, along the first axis, of an area of the wafer, (b) the specular reflection propagates along the second axis, (c) the first axis and the second axis are symmetrical about the normal, and (d) the normal is parallel to the optical axis of the partially blocking bright field unit.

2. The inspection system according to claim 1 , wherein the non-blocking bright field unit and the partially blocking bright field unit do not share any optical components.

3. The inspection system according to claim 1 , comprising a black and white camera that is positioned in the image plane.

4. The inspection system according to claim 1 , wherein the partially blocking bright field unit comprises a partially blocking aperture stop.

5. The inspection system according to claim 4 , wherein the partially blocking aperture stop is positioned in an objective lens exit pupil plane.

6. The inspection system according to claim 1 , wherein the partially blocking aperture stop comprises first type segments and second type segments that differ from each other by polarization.

7. The inspection system according to claim 1 , wherein the partially blocking aperture stop comprises first type segments and second type segments that differ from each other by spectral transmission.

8. The inspection system according to claim 1 , wherein the partially blocking aperture stop comprises first type segments and second type segments that differ from each other by transparency.

9. The inspection system according to claim 1 , comprising a group of aperture stops that comprise multiple aperture stops that virtually form a partially blocking aperture stop, wherein the multiple aperture stops comprises a first aperture stop and a second aperture stop, wherein the first aperture stop is located upstream to a second aperture stop.

10. The inspection system according to claim 9 , wherein when the aperture stops of the group when oriented at different orientations form different partially blocking aperture stops.

11. The inspection system according to claim 9 , wherein when the aperture stops of the group when positioned at different positions form different partially blocking aperture stops.

12. The inspection system according to claim 9 , wherein a first aperture stop of the multiple aperture stops is located in an illumination path and a second aperture stop of the multiple aperture stops is located in a collection path and downstream of an objective lens.

13. The inspection system according to claim 9 , wherein a first aperture stop of the multiple aperture stops is located in an illumination aperture stop plane and a second aperture stop of the multiple aperture stops is located in a re-imaged exit pupil plane.

14. The inspection system according to claim 1 , wherein the non-blocking bright field unit and the partially blocking bright field unit share at least one optical component.

15. The inspection system according to claim 14 , wherein the at least one optical component is a configurable spatial light modulator.

16. The inspection system according to claim 1 , comprising an objective changing unit that is configured to automatically replace objective lens that are used during an inspection process.

17. The inspection system according to claim 1 , comprising an aperture stop changing unit configured to replace aperture stops used during the inspection process changing the field blocking stops of the partially blocking bright field unit.

18. The inspection system according to claim 1 further comprising a processor for processing images acquired by at least one of the non-blocking bright field unit and the partially blocking bright-field unit.

19. The inspection system according to claim 18 , wherein the processor is configured to process the images and detect at least one defect out of inner cracks, bumps defects, epi pillar defects, bonded wafers inner layers defects.

20. The inspection system according to claim 18 , wherein the processor is configured to process the images and measure at least one dimension or at least one element that appears in one or more of the images.

21. An inspection method for inspecting a semiconductor substrate, the method comprises:
operating an inspection unit in a first mode, wherein the inspection unit comprise an exit pupil, an illumination module and an image sensor; wherein the operating in the first mode comprise illuminating an entirety of the exit pupil, and receiving by the image sensor light from the entirety of the exit pupil; and
operating the inspection unit in a second mode, wherein the operating in the second mode comprises positioning an aperture stop in the exit pupil thereby preventing the illumination module from illuminating the entirety of the exit pupil, and prevents, by blocking at least one specular reflectance, the image sensor from receiving light from the entirety of the exit pupil;
wherein when operating in the second mode the aperture stop is configured to (i) block any specular reflection that fulfills the following: (a) the specular reflection is caused by illuminating, along a first axis, of an area of the wafer, (b) the specular reflection propagates along a second axis, (c) the first axis and the second axis are symmetrical about a normal to the area of the wafer, and (d) the normal is parallel to an optical axis of the aperture stop, and (ii) allow transmission, through a partially blocking bright field unit, of some other specular reflected beams; and when operating in the first mode the aperture stop is configured to pass to the image plane any specular reflection that fulfills the following: (a) the specular reflection is caused by illuminating, along a first axis, of an area of the wafer, (b) the specular reflection propagates along the second axis, (c) the first axis and the second axis are symmetrical about the normal, and (d) the normal is parallel to the optical axis of the aperture stop.

22. The inspection method according to claim 21 , wherein the inspection unit comprises a group of aperture stops that comprise multiple aperture stops that virtually form a partially blocking aperture stop, wherein the multiple aperture stops comprises a first aperture stop and a second aperture stop, wherein the first aperture stop is located upstream to a second aperture stop.

23. A non-transitory computer readable medium that stores instructions for inspecting a semiconductor substrate by: performing a first inspecting session that comprises inspecting a first region of a first

Assignees

• Camtek Ltd

Inventors

• Ben Ezer Zehava
• Regensburger Menachem
• Koren Shimon
• Gilad Tomer
• Shapira Shy

Classifications

• H10P74/203

  Structural properties, e.g. testing or measuring thicknesses, line widths, warpage, bond strengths or physical defects · CPC title

• H10P72/0612

  Production flow monitoring, e.g. for increasing throughput · CPC title

• G01N21/9505 Primary

  Wafer internal defects, e.g. microcracks · CPC title

• G01N21/95623

  using a spatial filtering method (per se G02B) · CPC title

• G01N2021/557

  Detecting specular reflective parts on sample · CPC title