System for inspecting a backside of a wafer

Patent metadata

Field	Value
Publication number	US-10215707-B2
Application number	US-201615207537-A
Country	US
Kind code	B2
Filing date	Jul 12, 2016
Priority date	Jul 12, 2015
Publication date	Feb 26, 2019
Grant date	Feb 26, 2019

Abstract

An inspection system for inspection a surface of a substrate, the inspection system may include an interface for holding the substrate; a movement mechanism for moving the interface, thereby moving the substrate between different positions; a bright field light source that is configured to illuminate different bright field illuminated parts of the surface of the substrate when the substrate is positioned at the different positions; at least one dark field light source that is configured to illuminate different dark field illuminated parts of the surface of the substrate when the substrate is positioned at the different positions; and a camera that is configured to: (a) generate bright field detection signals in response to light that is detected by the camera as a result of the illumination of the different bright field illuminated parts; and (b) generate dark field detection signals in response to light that is detected by the camera as a result of the illumination of the different dark field illuminated parts; and wherein light that is detected by the camera as the result of the illumination of the different bright field illuminated parts and as the result of the illumination of the different dark field illuminated parts does not include an image of the camera.

First claim

We claim:

1. An inspection system for inspection a surface of a substrate, the inspection system comprises:
an interface for holding the substrate;
a moving mechanism for moving the interface, thereby moving the substrate between different positions;
a bright field light source that is configured to illuminate different bright field illuminated parts of the surface of the substrate when the substrate is positioned at the different positions;
at least one dark field light source that is configured to illuminate different dark field illuminated parts of the surface of the substrate when the substrate is positioned at the different positions; and
a camera that is configured to: (a) generate bright field detection signals in response to light that is detected by the camera as a result of the illumination of the different bright field illuminated parts; and (b) generate dark field detection signals in response to light that is detected by the camera as a result of the illumination of the different dark field illuminated parts;
wherein light that is detected by the camera as the result of the illumination of the different bright field illuminated parts and as the result of the illumination of the different dark field illuminated parts does not include an image of the camera;
wherein the surface of the substrate is a backside of the substrate; and
wherein at least one of the following is true:
a. the multiple dark field light sources are a first dark field source, a second dark field source, a third dark field source, and a fourth dark field source; wherein the first dark field source is parallel to the third dark field source; wherein the second dark field source is parallel to the fourth dark field source; and wherein the first dark field source is is perpendicular to the second dark field source;
b. an axis of rotation of the interface virtually crosses the bright field light source at a second crossing point that is spaced apart from a center of the bright field light source;
c. the camera and the bright field light source are positioned at substantially a same distance from a substrate backside plane in which the backside of the substrate is located; and
d. a distance between the dark field light source and the substrate backside plane is smaller than a distance between the camera and the substrate backside plane and is smaller than the distance between the bright field light source and the substrate backside plane.

2. The inspection system according to claim 1 wherein the moving mechanism is a rotating mechanism for rotating the interface thereby rotating the substrate between different positions.

3. The inspection system according to claim 1 , wherein the at least one dark field light source and the bright field light source are configured to illuminate the backside of the substrate in a non-overlapping manner.

4. The inspection system according to claim 1 , wherein the substrate is positioned at the different positions during different time periods; and wherein during at least one time period the bright field light source and the at least one dark field light source are configured to concurrently illuminate the backside of the substrate.

5. The inspection system according to claim 1 , wherein for each bright field illuminated part of the different bright field illuminated parts, when the bright field illuminated part is illuminated, an optical axis of the camera virtually crosses a substrate backside plane the at a first crossing point that is located outside the bright field illuminated part; and wherein the backside of the substrate is located within the substrate backside plane.

6. The inspection system according to claim 1 , wherein for each dark field illuminated part of the different dark field illuminated parts, when the dark field illuminated part is illuminated, an optical axis of the camera virtually crosses a substrate backside plane the at a crossing point that is located outside the dark field illuminated part; and wherein the backside of the substrate is located within the substrate backside plane.

7. The inspection system according to claim 1 , wherein the interface comprises different interface portions for supporting substrates of different sizes.

8. The inspection system according to claim 1 , wherein the different interface portions are coaxial and are positioned at different heights.

9. The inspection system according to claim 1 , comprising an alignment sensor and a controller; wherein the interface comprises an alignment target; wherein alignment sensor is configured to detect the alignment target; and wherein the controller is configured to control the movement mechanism in response to detection signals from the alignment sensors.

10. The inspection system according to claim 9 , wherein the controller is configured to maintain an alignment between an orientation of the substrate when the substrate is received by the inspection system and between an orientation of the substrate at an end of an inspection of the substrate.

11. The inspection system according to claim 1 , wherein the bright field light source is a flat dome that faces the backside of the substrate.

12. The inspection system according to claim 1 , wherein the at least one dark field light source comprises multiple dark field light sources.

13. The inspection system according to claim 12 , wherein multiple dark field light sources are configured to illuminate the backside of the substrate from different directions.

14. The inspection system according to claim 1 , wherein the multiple dark field light sources are the first dark field source, the second dark field source, the third dark field source, and the fourth dark field source; wherein the first dark field source is parallel to the third dark field source; wherein the second dark field source is parallel to the fourth dark field source; and wherein the first dark field source is is perpendicular to the second dark field source.

15. The inspection system according to claim 12 , wherein the multiple dark field light sources, the bright field light source and the camera are mechanically coupled to a supporting structure.

16. The inspection system according to claim 15 , wherein the supporting structure is a frame; wherein most of the bright field light source is positioned within the frame; and wherein the camera and at least one of the multiple dark field light sources are positioned outside the frame.

17. The inspection system according to claim 15 , wherein the substrate, when held by the interface, is positioned directly above a portion of the bright field light source.

18. The inspection system according to claim 12 , wherein multiple dark field light sources are arranged in an asymmetrical manner in relation to an axis of rotation of the interface.

19. The inspection system according to claim 1 , wherein the axis of rotation of the interface virtually crosses the bright field light source at the second crossing point that is spaced apart from the center of the bright field light source.

20. The inspection system according to claim 19 , wherein the bright field light source has a first side and a second side that are opposite to each other; wherein the camera is closer to the first side of the bright field light source; and wherein a distance between the second crossing point and the camera is a fraction of a distance between the second crossing point and the second side of the bright field light source.

21. The inspection system according to claim 1 , wh

Assignees

• Camtek Ltd

Inventors

• Ben Ezer Zehava
• Kafry Guy
• Koren Shimon
• Langmans Eldad
• Deutsch Natan

Classifications

• G01N2021/8825

  Separate detection of dark field and bright field · CPC title

• H04N7/183

  for receiving images from a single remote source · CPC title

• G01N21/9501

  Semiconductor wafers (manufacturing processes per se of semiconductor devices implementing a measuring step H10P74/20) · CPC title

• G01N21/8806 Primary

  Specially adapted optical and illumination features · CPC title

• H04N23/56

  provided with illuminating means · CPC title