Metrology System of Fine pattern for Process Control by Charged Particle Beam

Abstract

The present invention provides a pattern inspection technique that enables measurement and inspection of a fine pattern by a charged particle beam to be performed with high throughput. A metrology system of fine pattern according to the pattern inspection technique has: a the column that includes a charged particle source, an electron optics for scanning a desired observation area on a sample with a charged particle beam emitted from the charged particle source, and a detector for detecting charged particles generated secondarily from the sample scanned by the charged particle beam; information processing means for measuring information about geometry of a pattern formed on the sample based on information on the intensity of the charged particles obtained by the detector; and a sample introduction unit for introducing the sample into the inside of the column; wherein a charge neutralizer unit for generating ions and charge neutralizing the sample with the ions and surface potential measuring means for measuring a surface potential of the sample surface are provided on a path that is inside the sample introduction unit and transports the sample to the column.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, objects and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings wherein:

FIG. 1A is a diagram for explaining a structure of a sample introduction unit of a metrology system of fine pattern according to a first embodiment of the present invention;

FIG. 1B is a diagram for explaining a structure of a sample introduction unit of a metrology system of fine pattern according to a second embodiment of the present invention;

FIG. 2 is a diagram for explaining a configuration of a column of the metrology system of fine pattern using an electron beam to which the present invention is applied;

FIG. 3 is a diagram for explaining another example of structure of the sample introduction unit in the embodiment shown in FIG. 1B;

FIG. 4A is a diagram for explaining a change of the form of the electron beam on the sample by charge neutralization and an effect of the charge neutralization;

FIG. 4B is a diagram for explaining a change of the form of the electron beam on the sample by the charge neutralization and an effect of the charge neutralization;

FIG. 4C is a diagram for explaining a change of the form of the electron beam on the sample by the charge neutralization and an effect of the charge neutralization;

FIG. 4D is a graph for explaining a change of the form of the electron beam on the sample by the charge neutralization and an effect of the charge neutralization;

FIG. 4E is a graphical representation for explaining a change of the form of the electron beam on the sample by the charge neutralization and an effect of the charge neutralization;

FIG. 4F is a graphical representation for explaining a change of the form of the electron beam on the sample by the charge neutralization and an effect of the charge neutralization;

FIG. 5A is a diagram for explaining an installation method of a charge neutralizer of a soft x-ray irradiation type (hereinafter referred to as a soft x-ray irradiating charge neutralizer) in the embodiment shown in FIG. 3;

FIG. 5B is a diagram for explaining an installation method of the soft x-ray irradiating charge neutralizer in the embodiment shown in FIG. 3;

FIG. 5C is a diagram for explaining a structure of a charge neutralizer unit in the embodiment shown in FIG. 1;

FIG. 6 is a diagram for explaining a structure of a sample introduction unit of a metrology system of fine pattern according to a third embodiment of the present invention;

FIG. 7 is a diagram for explaining another example of structure of the sample introduction unit in the embodiment shown in FIG. 7;

FIG. 8 is a diagram for explaining further another example of structure of the sample introduction unit in the embodiment shown in FIG. 7;

FIG. 9 is a view showing a cross-section taken along a line B-B′ illustrated in FIG. 6;

FIG. 10A is a graph showing an example of an irradiation time of the soft x-ray irradiating charge neutralizer in the second embodiment;

FIG. 10B is a graph showing one example of a potential distribution before and after the charge neutralization of a sample; and

FIG. 11 is a diagram showing a configuration of arrangement of electrodes in the third embodiment of the present invention.

Claims

1. A metrology system of fine pattern for process control by charged particle beam, comprising: a column that includes a charged particle source, an electron optics for scanning a desired observation area on a sample with a charged particle beam emitted from the charged particle source, and a detector for detecting the charged particles generated secondarily from the sample scanned by the charged particle beam; information processing means for measuring information about geometry of a pattern formed on the sample based on information on the intensity of the charged particles obtained by the detector; anda sample introduction unit for introducing the sample into the inside of the column,wherein a charge neutralizer unit for generating ions and charge neutralizing the sample with the ions and surface potential measuring means for measuring a surface potential of the sample surface are provided on a path that is inside the sample introduction unit and transports the sample to the column.

2. The metrology system of fine pattern for process control by charged particle beam according to claim 1, Wherein the charge neutralizer unit has a charge neutralizer for generating ions by corona discharge and a rotation stage allowing the sample to be placed and held thereon and capable of rotation with the sample, andthe charge neutralizer is installed to place above the rotation stage.

3. The metrology system of fine pattern for process control by charged particle beam according to claim 2, Wherein the charge neutralizer unit is installed at a position whose distance to the sample mount plane of the rotation stage is not more than one half times the radius of the wafer.

4. The metrology system of fine pattern for process control by charged particle beam according to claim 1, Wherein mechanical arm means for wafer transportation that is inside the sample introduction unit and transports the sample to the rotation stage and the surface potential measuring means are provided.

5. A metrology system of fine pattern for process control by charged particle beam, comprising: a column that includes a charged particle source, an electron optics for scanning a desired observation area on a sample using a charged particle beam emitted from the charged particle source, and a detector for detecting charged particles generated secondarily from the sample scanned by the charged particle beam;information processing means for measuring information about geometry of a pattern formed on the sample based on information on the intensity of the charged particles obtained by the detector; anda sample introduction unit for introducing the sample into the inside of the column;wherein soft x-ray irradiating means for charge neutralizing the sample by irradiating soft x-ray onto the sample and charge neutralizing the sample, and surface potential measuring means for measuring a surface potential of a sample surface are provided on a path that is inside the sample introduction unit and transports the sample to the column.

6. The metrology system of fine pattern for process control by charged particle beam according to claim 5, Wherein the soft x-ray irradiating means has a plurality of soft x-ray irradiators and a rotation stage allowing the sample to be placed and held thereon and capable of rotation with the sample, andthe metrology system of fine pattern for process control by charged particle beam is so configured that the plurality of soft x-ray irradiators may be placed above the rotation stage.

7. The metrology system of fine pattern for process control by charged particle beam according to claim 6, Wherein the plurality of soft x-ray irradiators are placed at respective different distances from the center of the rotation stage and are installed at respective different heights to the sample mount plane of the rotation stage.

8. The metrology system of fine pattern for process control by charged particle beam according to claim 6, Wherein among the plurality of soft x-ray irradiators, the soft x-ray irradiators placed at short distance from the center of the rotation stage is installed at a higher position to a sample mount plane of the rotation stage than the soft x-ray irradiators placed at long distance from the center of the rotation stage.

9. The metrology system of fine pattern for process control by charged particle beam according to claim 5, Wherein the surface potential measuring means has at least one static probe and is configured to determine irradiation times of the plurality of soft x-ray irradiators using a measurement result of the at least one static probe.

10. The metrology system of fine pattern for process control by charged particle beam according to claim 5, Wherein the surface potential measuring means has two static probes on a path that is inside the sample introduction unit and transports the sample to the column, the two static probes being installed in previous and subsequent stages of the soft x-ray irradiating means, respectively, andthe metrology system is configured to determine an irradiation time of soft x-ray of the soft x-ray irradiating means using a measurement result by the static probe placed in the previous stage and is configured to determine focusing of the charged particle beam using a measurement result by the static probe placed in the subsequent stage.

11. The metrology system of fine pattern for process control by charged particle beam according to claim 5, further comprising: mechanical arm means for wafer transportation that is inside the sample introduction unit and transports the sample to the soft x-ray irradiating means and the surface potential measuring means.

12. A metrology system of fine pattern for process control by charged particle beam, comprising: a column that includes a charged particle source, an electron optics for scanning a desired observation area on a wafer sample using a charged particle beam emitted form the charged particle source, and a detector for detecting charged particles generated secondarily from the sample scanned by the charged particle beam;information processing means for measuring information about geometry of a pattern formed on the sample based on information on the intensity of the charged particles obtained by the detector; anda sample introduction unit for introducing the sample into the inside of the column;wherein charge neutralizing means for charge neutralizing the sample by impressing voltages on a plurality of electrodes and surface potential measuring means for measuring a surface potential of the sample surface are provided on a path that is inside the sample introduction unit and transports the sample to the column.

13. The metrology system of fine pattern for process control by charged particle beam according to claim 12, Wherein the charge neutralizing means has a rotation stage allowing the sample to be placed and held thereon and capable of rotation with the sample, and the plurality of electrodes are arranged at positions such that inter-electrode distances are equal to the length of a radius of the sample.

14. The metrology system of fine pattern for process control by charged particle beam according to claim 13, Wherein among the plurality of electrodes, the electrode placed at the center of the rotation stage and the electrode placed in surrounding of the center are impressed voltages of different polarities, respectively.

15. The metrology system of fine pattern for process control by charged particle beam according to claim 12, Wherein the surface potential measuring means has at least one static probe and determines impressed voltages and voltage impression times of the plurality of electrodes using a measurement result by the at least one static probe.

16. The metrology system of fine pattern for process control by charged particle beam according to claim 12, Wherein the surface potential measuring means has two static probes, the two static probes being installed in previous and subsequent stages of the charge neutralizing means, respectively, on a path that is inside the sample introduction unit and transports the sample to the column, andthe metrology system is configured to determine impressed voltages and voltage impression times of the plurality of electrodes using a measurement result by the static probe placed in the previous stage and is configured to determine focusing of the charged particle beam using a measurement result by the static probe placed in the subsequent stage.

17. The metrology system of fine pattern for process control by charged particle beam according to claim 12, further comprising: mechanical arm means for wafer transportation that is inside the sample introduction unit and transports the sample to the charge neutralizing means and the surface potential measuring means.

18. The metrology system of fine pattern for process control by charged particle beam according to any one of claims 1, 5, and 12, Wherein the metrology system is configured to correct focusing by feeding back to a retarding voltage a value of the surface potential of the sample measured by the surface potential measuring means before transportation of the sample to the column.

19. The metrology system of fine pattern for process control by charged particle beam according to claim 12, Wherein the plurality of electrodes of the charge neutralizing means are arranged, being opposed to the sample, at positions whose spacings to the sample plane are larger than the diameter of the sample.

20. The metrology system of fine pattern for process control by charged particle beam according to claim 12, wherein, while the charge neutralizing means is charge neutralizing the sample, the sample is grounded or the sample is connected to an electrically conductive member grounded near the sample.