Charged particle beam apparatus

• US 9,177,757 B2
• Filed: 06/21/2013
• Issued: 11/03/2015
• Est. Priority Date: 08/03/2012
• Status: Active Grant

• Current Assignee: Hitachi High-Tech Company Limited (Hitachi, Ltd.)
• Original Assignee: Hitachi High-Technologies Corporation (Hitachi, Ltd.)
• Inventors: Ban, Naoma, Obara, Kenji, Hirai, Takehiro
• Primary Examiner(s): IPPOLITO, NICOLE MARIE
• Application Number:
  US14/417,647
• Publication Number:
  US 20150170875A1
• Time in Patent Office: 865 Days
• Field of Search: 250/305, 250/306, 250/307, 250/309, 250/310, 250/311, 250/492.1, 250/492.2, 250/492.3
• US Class Current: 1/1
• CPC Class Codes: H01J 2237/049 Focusing means
• CPC Class Codes: H01J 2237/063 Electron sources
• CPC Class Codes: H01J 2237/221 Image processing
• CPC Class Codes: H01J 2237/2448 Secondary particle detectors
• CPC Class Codes: H01J 2237/24585 Other variables, e.g. energy, mass, velocity, time, temperature
• CPC Class Codes: H01J 2237/24592 Inspection and quality control of devices
• CPC Class Codes: H01J 2237/2602 Details
• CPC Class Codes: H01J 2237/2803 characterised by the imaging method
• CPC Class Codes: H01J 2237/2817 Pattern inspection
• CPC Class Codes: H01J 37/04 Arrangements of electrodes and associated parts for generating or controlling the discharge, e.g. electron-optical arrangement or ion-optical arrangement H01J37/32009, H01J37/32623, H01J37/3266, H01J37/32697 take precedence; electron or ion-optical systems for localised treatment of objects H01J37/3007
• CPC Class Codes: H01J 37/222 Image processing arrangements associated with the tube
• CPC Class Codes: H01J 37/261 Details
• 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 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

The present invention relates to a defect inspection apparatus based on the fact that contrasts of a grain and a void of a semiconductor copper interconnect in a scanning electron microscope are changed depending on electron beam irradiation accelerating voltages. A charged particle beam apparatus of the present invention irradiates the same portion of a specimen with electron beams at a plurality of accelerating voltages, and differentiates a grain (65, 66) from a void (67) on the basis of a contrast change amount of the same portion in a plurality of images (61, 62) acquired so as to respectively correspond to the plurality of accelerating voltages. Consequently, it is possible to automatically detect a grain and a void in a differentiation manner at a high speed without destructing a specimen.

Claims

1. A charged particle beam apparatus comprising:

an electron optical system that focuses electron beams and irradiates a specimen with the electron beams;

a detector that detects secondary electrons or reflected electrons generated from the specimen due to irradiation with the electron beams; and

an image processing unit that compares a plurality of images with each other so as to detect a defect,

wherein the electron optical system irradiates the same portion of the specimen with the electron beams at a plurality of accelerating voltages, and

wherein the image processing unit differentiates a grain from a void on the basis of a contrast change amount of the same portion in a plurality of images which are acquired so as to respectively correspond to the plurality of accelerating voltages.

2. The charged particle beam apparatus according to claim 1,

wherein the plurality of accelerating voltages are determined on the basis of a difference between contrast dependency of the grain on an accelerating voltage change of the electron beams and contrast dependency of the void on an accelerating voltage change of the electron beams.

3. The charged particle beam apparatus according to claim 1,

wherein the plurality of images include at least a first image captured at a first accelerating voltage and a second image captured at a second accelerating voltage different from the first accelerating voltage,

wherein a contrast difference between the void and the grain at the first accelerating voltage is larger than a contrast difference between the void and the grain at the second accelerating voltage, and

wherein the image processing unit obtains a difference between the first image and the second image by comparing the first image with the second image, and determines that a region of the difference is the void.

4. A charged particle beam apparatus comprising:

an electron optical system that focuses electron beams and irradiates a specimen with the electron beams;

a detector that detects secondary electrons or reflected electrons generated from the specimen due to irradiation with the electron beams; and

an image processing unit that compares a plurality of images with each other so as to detect a defect,

wherein the electron optical system irradiates the same portion of the specimen with the electron beams at a plurality of accelerating voltages, and

wherein the image processing unit identifies a void located at a depth designated in advance from a surface of the specimen on the basis of a contrast change amount of the same portion in a plurality of images which are acquired so as to respectively correspond to the plurality of accelerating voltages.

5. The charged particle beam apparatus according to claim 4,

wherein the plurality of accelerating voltages are determined on the basis of a difference between contrast dependency of avoid located at a first depth on an accelerating voltage change of the electron beams and contrast dependency of a void located at a second depth different from the first depth on an accelerating voltage change of the electron beams.

6. The charged particle beam apparatus according to claim 4,

wherein the plurality of images include at least a first image captured at a first accelerating voltage and a second image captured at a second accelerating voltage different from the first accelerating voltage,

wherein the first image and the second image include at least an image of a first void and an image of a second void located at a depth different from a depth of the first void,

wherein a contrast difference between the first void and the second void at the first accelerating voltage is larger than a contrast difference between the first void and the second void at the second accelerating voltage, and

wherein the image processing unit obtains a difference between the first image and the second image by comparing the first image with the second image, and determines that a region of the difference is the first void or the second void.