Wafer inspection system and wafer inspection process using charged particle beam

• US 20020134936A1
• Filed: 01/04/2002
• Published: 09/26/2002
• Est. Priority Date: 03/23/2001
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Nozoe, Mari, Takafuji, Atsuko, Matsui, Miyako
• Granted Patent: US 6,700,122 B2
• Time in Patent Office: Days
• US Class Current: 250/310
• CPC Class Codes: H01J 2237/281 Bottom of trenches or holes
• CPC Class Codes: H01J 2237/2817 Pattern inspection
• CPC Class Codes: H01J 37/28 with scanning beams H01J37/268, H01J37/292, H01J37/2955 take precedence

Abstract

The present invention provides a wafer inspection technique capable of detecting a defect in a wafer on which a pattern having a large step such as a contact hole being subjected to a semiconductor manufacturing process is formed and obtaining information such as the position and kind of a defect such as a hole with open contact failure caused in dry etching process at high speed. A wafer on which a pattern having a large step being subjected to a semiconductor manufacturing process is formed is scanned and irradiated with an electron beam having irradiation energy which is in a range from 100 eV to 1,000 eV, and a defect is detected at high speed from an image of secondary electrons generated. Before the secondary electron image is captured, the wafer is irradiated with an electron beam at high speed while being moved to thereby charge the surface of the wafer with a desired charging voltage. The kind of the defect is determined from the captured secondary electron image, and a distribution of defects in the plane of the wafer is displayed.

Claims

1. A wafer inspection system using a charged particle beam, comprising:

a charged particle source;

an objective lens for irradiating a wafer on which a pattern including a hole pattern is formed with a primary charged particle beam from said charged particle source;

a sample stage for holding said wafer;

a charged particle generator for positively charging the surface of said wafer placed on said sample stage;

a deflector for irradiating a predetermined area in said wafer positively charged with a primary charged particle beam; and

a detector for detecting a secondary charged particle from said wafer positively charged,

wherein an inspection is conducted on said hole pattern on the basis of a signal from said detector.

2. The wafer inspection system using a charged particle beam according to claim 1, wherein an electron source is provided as said charged particle generator.

3. A wafer inspection system using a charged particle beam, comprising:

a charged particle source;

an objective lens for irradiating a wafer on which a pattern including a hole pattern is formed with a primary charged particle beam from said charged particle source;

a sample stage for holding said wafer;

a charged particle generator for positively charging the surface of said wafer placed on said sample stage;

a deflector for scanning and irradiating a predetermined area in said wafer charged by said charged particle generator with a primary charged particle beam;

a detector for detecting a secondary charged particle from said wafer charged;

an energy filter disposed between said sample stage and said detector so as to select and pass an energy of the secondary charged particle; and

a control unit for controlling said charged particle generator on the basis of a signal from said detector.

4. A wafer inspection system using a charged particle beam, comprising:

a charged particle source;

a first deflector for scanning a wafer on which a pattern including a contact hole is formed with a primary charged particle beam from said charged particle source;

an objective lens for irradiating said wafer on which the pattern including the contact hole is formed with the primary charged particle beam;

a sample stage for holding said wafer;

a positive charged particle generator for positively charging the surface of said wafer placed on said sample stage;

a deflector for irradiating a predetermined area in said wafer positively charged;

a detector for detecting a secondary charged particle from said wafer positively charged;

a decelerator which is provided for said sample stage and operates so as to decelerate the primary charged particle beam and accelerate the secondary charged particle; and

a second deflector filter disposed between said first deflector and said objective lens, for separating the primary charged particle and the secondary charged particle from each other,

wherein an inspection is conducted on said contact hole on the basis of a signal from said detector.

5. The wafer inspection system using a charged particle beam according to claim 4, wherein said decelerator supplies a negative voltage.

6. The wafer inspection system using a charged particle beam according to claim 4, wherein said second deflector is an EXB type deflector.

7. A wafer inspection system using a charged particle beam, comprising:

a sample stage for holding a sample;

a first charged particle beam source for supplying a first charged particle beam to a sample having a hole pattern;

a second charged particle beam source for supplying a second charged particle beam;

a switch for making a switch between said first charged particle beam and said second charged particle beam to irradiate said sample having the hole pattern with the selected charged particle beam;

an objective lens for irradiating said sample irradiated with said first or second charged particle beam with a third charged particle beam; and

a detector for detecting a fourth charged particle from said sample,

wherein an inspection is conducted on said hole pattern on the basis of a signal from said detector.

8. A wafer inspection process using a charged particle beam, comprising:

a step of holding a wafer on which a pattern including a hole pattern is formed on a sample stage;

a step of charging the surface of said wafer placed on said sample stage with a positive charged particle;

a deflecting step of scanning and irradiating said wafer with a primary charged particle beam;

a step of detecting a secondary charged particle from said wafer positively charged by a detector; and

a step of determining whether said hole pattern is good or not on the basis of a signal from said detector.

9. The wafer inspection process using a charged particle beam according to claim 8, wherein as said charging step, a step of setting a voltage of the surface of said wafer to a range from 5 volts to 50 volts is included.

10. The wafer inspection process using a charged particle beam according to claim 8, wherein as said charging step, a step of controlling irradiation energy of said positive charged particle to a range from 100 electron volts to 1,000 electron volts is included.