Method and system for measuring bumps based on phase and amplitude information

• US 9,147,102 B2
• Filed: 01/02/2012
• Issued: 09/29/2015
• Est. Priority Date: 01/02/2012
• Status: Active Grant

• Current Assignee: Camtek Limited (Hexagon AB)
• Original Assignee: Camtek Limited (Hexagon AB)
• Inventors: Koren, Shimon, Shur, Or, Malinovich, Yacov, Golan, Gilad
• Primary Examiner(s): Patel, Jayesh A
• Assistant Examiner(s): Thomas, Mia M
• Application Number:
  US13/342,119
• Publication Number:
  US 20130170712A1
• Time in Patent Office: 1,366 Days
• US Class Current: 1/1
• CPC Class Codes: G01B 11/0608 Height gauges
• CPC Class Codes: G01N 21/95607 using a comparative method
• CPC Class Codes: G01N 21/95684 Patterns showing highly reflecting parts, e.g. metallic elements
• CPC Class Codes: G02B 21/0016 Technical microscopes, e.g. for inspection or measuring in industrial production processes
• CPC Class Codes: G02B 21/0056 based on optical coherence, e.g. phase-contrast arrangements, interference arrangements
• CPC Class Codes: G06V 20/69 Microscopic objects, e.g. biological cells or cellular parts

Abstract

A method and device for measuring a height of a microscopic structure such as solder bumps. For simplicity of explanation, the invention is described with respect to phase information and amplitude information wherein phase detection and calculation algorithms are being used.

Claims

1. A device for measuring a height of a microscopic structure, the device comprises:

a storage circuit arranged to store information that comprises amplitude information and phase information, wherein the stored information is indicative of a shape and a size of the microscopic structure;

a mask generation circuit arranged to threshold pixels of the amplitude information to provide a mask that comprises masked amplitude pixels that have amplitude values above an amplitude threshold;

a phase information circuit arranged to apply the mask on the phase information to provide masked phase pixels;

select, out of the masked phase pixels, selected phase pixels that form a part of the masked phase pixels and correspond to a phase criterion, the selected phase pixels have selected phase pixels attribute values;

find, out of the phase information, elected phase pixels that have the selected phase pixel attribute values; and

a height calculation circuit arranged to generate a height measurement result based the elected phase pixels.

2. The device according to claim 1, wherein the mask generation circuit is arranged to check whether the mask has at least a predetermined number of pixels;

wherein if the mask does not have the at least predetermined number of pixels then the mask generation circuit is arranged to lower the amplitude information to provide a modified amplitude threshold; and

wherein the phase information circuit is arranged to threshold the pixels of the amplitude information using the modified amplitude threshold.

3. The device according to claim 1, wherein the microscopic structure is a solder bump.

4. The device according to claim 3, wherein the mask generation circuit is arranged to check whether the mask has at least a predetermined number of pixels;

wherein if the mask does not have the at least predetermined number of pixels then;

(a) the mask generation circuit is arranged to lower the amplitude information to provide a modified amplitude threshold and

(b) the phase information circuit is arranged to threshold the pixels of the amplitude information using the modified amplitude threshold.

5. The device according to claim 3, wherein the phase criterion represent a statistical criterion selected out of an average, a standard deviation, a weight average or a median.

6. The device according to claim 3, wherein the height calculation circuit is arranged to generate a height measurement result based on a predefined approximation of the shape of the microscopic structure and on the elected phase pixels.

7. The device according to claim 1, wherein the phase criterion represent a statistical criterion selected out of an average, a standard deviation, a weight average or a median.

8. The device according to claim 1, wherein the height calculation circuit is arranged to generate the height measurement result based on a predefined approximation of the shape of the microscopic structure and on the elected phase pixels.

9. A method for measuring a height of a microscopic structure, the method comprises:

receiving or generating information that comprises amplitude information and phase information, wherein the stored information is indicative of a shape and a size of the microscopic structure;

thresholding pixels of the amplitude information to provide a mask that comprises masked amplitude pixels that have amplitude values above an amplitude threshold;

applying the mask on the phase information to provide masked phase pixels;

selecting, out of the masked phase pixels, selected phase pixels that form a part of the masked phase pixels and correspond to a phase criterion, the selected phase pixels have selected phase pixels attribute values;

finding, out of the phase information, elected phase pixels that have the selected phase pixel attribute values; and

generating a height measurement result based the elected phase pixels.

10. The method according to claim 9, comprising:

checking whether the mask has at least a predetermined number of pixels;

wherein if the mask does not have the at least predetermined number of pixels then lowering the amplitude information to provide a modified amplitude threshold; and

thresholding the pixels of the amplitude information using the modified amplitude threshold.

11. The method according to claim 9, wherein the microscopic structure is a solder bump.

12. The method according to claim 11, comprising:

checking whether the mask has at least a predetermined number of pixels;

wherein if the mask does not have the at least predetermined number of pixels then;

(a) lowering the amplitude information to provide a modified amplitude threshold and

(b) thresholding the pixels of the amplitude information using the modified amplitude threshold.

13. The method according to claim 11, wherein the phase criterion represent a statistical criterion selected out of an average, a standard deviation, a weight average, a median.

14. The method according to claim 11, comprising generating a height measurement result by generating an approximation of the shape and size of the microscopic structure based on a predefined approximation of the shape of the microscopic structure and on the elected phase pixels.

15. The method according to claim 9, wherein the phase criterion represent a statistical criterion selected out of an average, a standard deviation, a weight average, a median.

16. The method according to claim 9, comprising generating the height measurement result by generating an approximation of the shape and size of the microscopic structure based on a predefined approximation of the shape of the microscopic structure and on the elected phase pixels.