Electron beam inspection method and apparatus and semiconductor manufacturing method and its manufacturing line utilizing the same

• US 5,986,263 A
• Filed: 03/26/1997
• Issued: 11/16/1999
• Est. Priority Date: 03/29/1996
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Watanabe, Masahiro, Hiroi, Takashi, Nozoe, Mari, Takagi, Yuji, Tanaka, Maki, Kuni, Asahiro, Sugimoto, Aritoshi, Shinada, Hiroyuki, Matsuyama, Yukio
• Primary Examiner(s): Anderson, Bruce C.
• Application Number:
  US08/824,413
• Time in Patent Office: 965 Days
• Field of Search: 250/310, 250/397, 250/492.2
• US Class Current: 250/310
• 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

An electron beam inspection method and apparatus. The method includes controlling acceleration voltage of electron beam and electric field on a sample, beam current, beam diameter, image detection rate, image dimensions, precharge, discharge, or a combination of them, exposing an object to the electron beam, detecting in a sensor a physical change generated from the object, and inspecting or measuring the object on the basis of a signal representing the detected physical change. The apparatus includes an electron source (potential E2) for generating an electron beam, a deflector for scanning generated electrons, an objective lens for focusing the electron beam upon the object, a grid (potential E1) disposed between the object and the objective lens, a wafer holder (potential E0) for holding the object, a sensor for detecting generated secondary electrons, a potential controller for controlling the potential E0, E1 and E2, and a storage for storing optimum potential conditions. By changing conditions of an electron optic system such as potential E0, E1 and E2, the acceleration voltage and electric field on the object are controlled. For a material located at least in an upper layer of a plurality of materials forming the object, the secondary electron yield ratio can be made nearly unity and appropriate contrast of an obtained image can be provided with minimized influence of charge up.

Claims

1. An electron beam inspection method comprising the steps of:

irradiating an electron beam to an object to be inspected;

detecting at least one of a secondary electron and a reflected electron emanated from the object by the irradiation of the electron beam;

obtaining an image of the object from the detected electron;

controlling at least one of an acceleration voltage of the electron beam and an electric field in a neighborhood of the object based on the obtained image of the object so as to control the contrast of the image;

exposing the object to the electron beam with the controlled acceleration voltage;

detecting at least one of a secondary electron and reflected electron emanated from the object by the irradiation of the electron beam in the controlled electric field; and

conducting inspection or measurement of the object on the basis of a detected signal of the detection in the controlled electric field.

2. An electron beam inspection method according to claim 1, wherein said acceleration voltage of the electron beam is in the range of 0.3 to 5 kV.

3. An electron beam inspection method according to claim 1, wherein said electric field in the neighborhood of the object is 5 kV/mm or less.

4. An electron beam inspection method according to claim 1, wherein the steps of detecting include detecting the secondary electron emanated from the object, and the step of obtaining an image of the object is obtained from the detected secondary electron.

5. An electron beam inspection method according to claim 1, further comprising the steps of:

displaying a signal representing the detected signal by the detection in the controlled electric field on a display means.

6. An electron beam inspection method according to claim 1, further comprising the steps of detecting a height of the object, and controlling a focus of the electron beam irradiating the object based on the detected height of the object.

7. An electron beam inspection method according to claim 1, wherein the step of controlling further includes at least one of controlling an electric field on the object, a beam current, an image detection rate, image dimensions, pre charge of the surface of the object and discharge of the surface of the object.

8. An electron beam inspection apparatus comprising:

an electron source;

a beam deflector for deflecting an electron beam emitted from said electron source;

a height detector for detecting a height of a surface of an object to be inspected;

an objective lens for focusing the electron beam emitted from said electron source upon the object using an output from the height detector;

potential control means for controlling at least one of an acceleration voltage of the electron beam and an electric field in a neighborhood of the object;

a sensor for detecting at least one of a secondary electron and reflected electron emanated from the object by the irradiation of the electron beam; and

image processing means for conducting inspection or measurement of the object using an output from the sensor.

9. An electron beam inspection apparatus according to claim 8, further comprising display means for displaying a signal of an output from the sensor.

10. An electron beam inspection apparatus according to claim 8, wherein the potential control means controls at least one of an acceleration voltage of the electron beam and an electric field in a neighborhood of the object on a basis of an output of the image processing means.

11. An electron beam inspection apparatus according to claim 8, wherein the control means controls at least one of an acceleration voltage of the electron beam, an electric field in a neighborhood of the object, a current of the electron beam, a diameter of the electron beam, an image detection rate of the sensor, image dimensions in the control means, pre-charge on the surface of the object and discharge on the surface of the object.

12. An electron beam inspection apparatus comprising:

an electron source;

a beam deflector for deflecting an electron beam emitted from said electron source;

a height detector for detecting a height of a surface of an object to be inspected;

an objective lens for focusing the electron beam emitted from said electron source upon the object using an output from the height detector;

a sensor for detecting a at least one of a secondary electron and reflected electron emanated from the object, upon exposure of the object to the electron beam;

an inspection condition creation means for creating inspection conditions corresponding to a charge-up phenomenon on a surface of the object;

image processing means for conducting inspection or measurement of the object using an output from the sensor.

13. An electron beam inspection apparatus according to claim 12, wherein the inspection condition creation means provides the surface of the object with a pre-charge or discharge.

14. A semiconductor fabrication method comprising the steps of:

controlling at least one of an acceleration voltage of an electron beam and an electric field in a neighborhood of an object;

detecting a height of a surface of the object by a height detection unit;

adjusting a focus of the electron beam using a result of the detection by the height detection unit;

exposing the object to the electron beam with the controlled acceleration voltage;

detecting in a sensor at least one of a secondary electron and reflected electron emanated from the object generated from a semiconductor substrate as the object in response to said controlled electric field; and

conducting inspection or measurement of the semiconductor substrate on the basis of a signal representing the detected at least one of a secondary electron and reflected electron emanated from the object and thereby fabricating the semiconductor substrate.

17. A semicondutor fabrication method according to one of claims 14, 15, or 16, wherein a result of said inspection or measurement is analyzed and fed back to a predetermined process.

15. A semiconductor fabrication method comprising the steps of:

controlling an acceleration voltage of an electron beam on a sample, an electric field on the sample, a beam current, a beam diameter, an image detection rate, image dimensions, pre-charge, discharge or a combination of them;

detecting a height of a surface of the sample by a height detection unit;

adjusting a focus of the electron beam using a result of the detection by the height detection unit;

exposing a semiconductor substrate as the sample to the electron beam;

detecting in a sensor at least one of a secondary electron and reflected electron emanated from the semiconductor substrate; and

conducting inspection or measurement of the semiconductor substrate on the basis of a signal representing the detected at least one of a secondary electron and reflected electron emanated from the object and thereby fabricating the semiconductor substrate.

16. A semiconductor fabrication method comprising the steps of:

detecting a height of a surface of the semiconductor substrate by a height detection unit;

adjusting a focus of the electron beam using a result of the detection by the height detection unit;

exposing the semiconductor substrate to the electron beam;

detecting in a sensor at least one of a secondary electron and reflected electron emanated from the semiconductor substrate; and

conducting inspection or measurement of the semiconductor substrate on the basis of a signal representing the detected at least one of a secondary electron and reflected electron emanated from the object under inspection conditions corresponding to a charge-up phenomenon on the surface of the semiconductor substrate and thereby fabricating the semiconductor substrate.

18. An electron inspection method, comprising the steps of:

utilizing an object to be inspected comprising a conductive member and a dielectric member, at least one of the conductive member and the dielectric member being subjected to charge up when an electron beam is incident on the object;

setting an accelerating voltage of the electron beam and an electric field in a neighborhood of the object so as to substantially prevent the at least one of the conductive member and the dielectric member from being charged up when the electron beam is incident on the object;

exposing the object to the electron beam so that the electron beam is incident on the object;

detecting at least one of a secondary electron and reflected electron emanated from the object in response to the electron beam being incident on the object; and

conducting inspection or measurement of the object in accordance with the detected at least one of a secondary electron and reflected electron.

19. An electron beam inspection method, comprising the steps of:

utilizing an object to be inspected comprising at least two members thereon;

setting an accelerating voltage of the electron beam so that secondary electron yield ratios of each of the at least two members is substantially equal to 1 when the electron beam is incident on the object;

exposing the object to the electron beam so that the electron beam is incident on the object;

detecting a secondary electron emanated from the object in response to the electron beam being incident on the object; and

conducting inspection or measurement of the object in accordance with the detected secondary electron.

20. An electron beam inspection method according to claim 19, wherein the step of setting an accelerating voltage of the electron beam is based on a detected secondary electron emanated from the object by the incidence of the electron beam.

21. An electron beam inspection method according to claim 19, wherein the step of setting further includes setting an electric field in a neighborhood of the object.