JP2000100369A - Charged particle beam system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a lowering in the accuracy of pattern observation or inspection on the basis of information signals from a target via the irradiation of each charged particle beam, and an electron beam property measurement or the like. SOLUTION: This charged particle beam device has a shielding cylinder fitted to a column support member 8 so as to surround each of detector support members 10i, 10j and 10k, and reflected electron detectors 11i, 11j and 11k laid immediately below each of electron beam columns 1i, 1j and 1k. In this case, the length of the shading cylinder in the optical axis direction is set approximately so that an electron beam irradiation zones on a target in a certain column and the detection plane of reflected electron detector in an adjacent column are not visible to each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a multi-beam type charged particle beam apparatus.

[0002]

2. Description of the Related Art A scanning electron microscope scans a target with an electron beam, detects secondary electrons (reflected electrons, secondary electrons, etc.) from the target by the scanning, and displays the same on a display device (for example, a cathode ray tube). The target image based on the secondary electronic signal is displayed on the screen. Recently, such a scanning electron microscope has been applied to pattern observation and pattern inspection using a target material (eg, wafer) on which a pattern is drawn.

Now, in such an electron beam apparatus,
There is a multi-beam type in which each of a plurality of beams is irradiated onto each of the shared areas on the target, and secondary electrons generated by each irradiation are detected independently.

FIG. 1 is a conceptual diagram showing an example of a multi-beam type electron beam apparatus. In the figure, 1a, 1b, ..., 1
n is an electron beam column, and each column is provided with, for example, an electron gun 2, a focusing lens 3, a deflector 4, an objective lens 5, and the like as shown in FIG. Reference numeral 6 denotes a stage on which a target 7 such as a wafer is placed. Each column, target 7 and stage 6
Are all located in a main vacuum column (not shown). Each of the columns is fitted into through holes 9a to 9n of a common column support member 8 as shown in FIG. 3, for example, so that an appropriate distance is maintained between the lower end of each column and the target 7. Then, the support member is attached to an inner wall of a main column (not shown). Now, a backscattered electron detector is provided below each electron beam column. For example, as shown in FIG. 4, each column 1i, 1j, 1
The backscattered electron detectors 11i, 11j, 11k are attached to the column support member 8 via the detector support members 10i, 10j, 10k so as to face the lower end of k.

In such an apparatus, each column 1a, 1
b,..., 1n, the electron beam from the electron gun 2 is focused on the target 7 by the focusing lens 3 and the objective lens 5, and the deflector 4 assigns each area on the target 7 (for example, In the case of a wafer, a predetermined range within, for example, a chip area) is scanned. The backscattered electrons generated from the target 7 by the scanning are detected by respective backscattered electron detectors provided opposite to the lower end of each column, and based on the information signal based on the backscattered electrons, the respective regions of the target are detected. Pattern observation, pattern inspection, and the like are performed simultaneously. As described above, the multi-beam type significantly increases the speed of pattern observation and pattern inspection as compared with pattern observation and pattern inspection using one electron beam column.

In the above example, the pattern observation and the pattern inspection have been described. However, the electron beam focused on the material to be drawn is deflected to a predetermined position on the material to be drawn to draw a pattern. However, if a multi-beam type is used and a pattern is simultaneously drawn on each dedicated area on the material to be drawn, a remarkable speed of pattern drawing can be similarly increased. The electron beam apparatus such as the electron beam lithography apparatus is also provided with a detector for detecting secondary electrons in each column similarly to the electron beam apparatus for pattern observation and pattern inspection, The properties and the like of each electron beam are measured simultaneously based on the signal from the instrument.

[0007]

As described above, each column of the multi-beam type electron beam apparatus is provided with a dedicated secondary electron beam detector, which is generated by irradiating each column with the electron beam. The captured secondary electrons are captured by dedicated detectors, respectively.Because the electron beam columns are close to each other, the detectors of a certain electron beam column are used to detect the electrons in the vicinity of the electron beam column. Secondary electrons generated by electron beam irradiation in the beam column are also mixed. For this reason, the SN ratio of the detection signal from each detector is deteriorated, and the accuracy of pattern observation, pattern inspection, or electron beam property measurement of a target portion handled by each electron beam column is reduced.

An object of the present invention is to solve such problems and to provide a novel charged particle beam device.

[0009]

A charged particle beam apparatus according to the present invention for achieving the above object has an electron optical system for irradiating a target with each charged particle beam passing through an independent optical path. In a charged particle beam apparatus, a detector for detecting secondary electrons generated by irradiating the target with each beam is provided exclusively for each charged particle beam.
A member is provided for blocking secondary electrons generated from the target by irradiation with another charged particle beam from entering a dedicated detector.

Further, the charged particle beam apparatus according to the present invention includes a plurality of columns having an electron optical system, and detects secondary electrons generated from a target by irradiation of the charged particle beam passing through each column. In a charged particle beam device in which a detector is provided exclusively for each column, secondary electrons generated from the target due to irradiation of the charged particle beam passing through other columns are mixed into the dedicated detector. Characterized in that a member for shutting off is provided.

Further, the charged particle beam apparatus of the present invention is characterized in that a negative potential is applied to the shielding member for electrons from the target.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 5 schematically shows a main part of an electron beam apparatus according to the present invention. In the figure, components denoted by the same reference numerals as those used in FIG. 4 are the same components.

In FIG. 1, reference numerals 1i, 1j, and 1k denote electron beam columns. Actually, as shown in FIG. 1, there are 1a to 1n, and only some of them are shown for convenience of explanation. 12 in the figure
i, 12j, 12k are the electron beam columns 1i, 1
j, 1k, each detector support member 10i,
10j, 10k and backscattered electron detectors 11i, 11j, 11
k is a shielding cylinder attached to the column supporting member 8 so as to surround the electron beam irradiation area on the target in one column and the reflected electron detector in the adjacent column. Are so long that they cannot be seen from each other.

In the electron beam apparatus having such a configuration, the electron beam from the electron gun 2 is focused on the target 7 by the focusing lens 3 and the objective lens 6 in each of the columns 1i, 1j, 1k,. At the same time, the deflector 4 scans a predetermined range in each assigned area on the target 7 (for example, when the target is a wafer, for example, a chip area). The backscattered electrons generated from the target 7 by the scanning are respectively provided to the dedicated backscattered electron detectors 11i, 11j, 1 provided opposite to the lower end of each column.
, 11n, and the pattern observation and pattern inspection of each target area are simultaneously performed based on the information signal based on the reflected electrons.

At this time, when attention is paid to a certain electron beam column 1j, a target portion immediately below the column, that is, most of the reflected electrons generated from the electron beam irradiation area shared by the column, is replaced by the column. Dedicated, ie, backscattered electron detector 11 provided directly above the electron beam irradiation area
It goes in the j direction, but a part goes in the direction of the backscattered electron detector of another column. However, the backscattered electrons directed in this direction are blocked by the shielding tube 12j, and are not detected by the dedicated backscattered electron detector in a column around the column.

As described above, the reflected electrons generated from the target 7 by the irradiation of the electron beam from each electron beam column are detected by the reflected electron beam detector dedicated to each column, and mixed into the reflected electron detector dedicated to other columns. I will not do it.

As a result, the SN of the detection signal from each detector
The ratio is not deteriorated, and the accuracy of pattern observation and pattern inspection of the target portion handled by each electron beam column does not decrease. In the above embodiment,
Although the detection of reflected electrons has been described as an example, the present invention is also applicable to the case of detecting secondary electrons from a target.

Further, in the above-described embodiment, the electron beam apparatus in which the dedicated detector of each electron beam column is provided immediately below each column is shown, but each dedicated detector is provided inside each column or outside each column. Therefore, the present invention can be naturally applied to an electron beam device provided near the optical axis of the column.

In the above embodiment, an electron beam apparatus for observing a pattern or inspecting a pattern has been described as an example.
The present invention is also applicable to an electron beam apparatus for performing pattern drawing, an ion beam apparatus for performing pattern observation, and the like.

Each of the shielding cylinders 12i, 12j, 12k
By applying a negative potential to the electrons from the target, the electrons coming toward the shielding cylinder can be repelled, and the shielding effect that does not mix with the detector dedicated to the surrounding column, and to the own detector Detection efficiency is improved.

Further, in the above embodiment, the shielding cylinder is used as the shielding member. However, if the secondary electron generated by the irradiation of the other column with the electron beam can be prevented from being mixed into the detector, the above embodiment may be used. It is not limited to the shape shown in the example. For example, the shape may be empty and square.

Further, in the above embodiment, a multi-column type electron beam apparatus has been described as an example of a multi-beam type electron beam apparatus, but a plurality of electron guns and an electron optical system are provided. To the electron beam from one electron beam source into multiple electron beams, and pass each electron beam through multiple electron optical systems. The present invention is applicable.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing an example of a multi-beam electron beam device.

FIG. 2 shows a configuration inside an electron beam column.

FIG. 3 shows an example of a column support member.

FIG. 4 schematically shows a main part of a multi-beam electron beam apparatus.

FIG. 5 schematically shows a main part of a multi-beam electron beam apparatus as one embodiment of the present invention.

[Explanation of symbols]

1a to 1n: electron beam column, 7: target, 8 ...
Column support members, 9a to 9n ... through holes, 10a to 10n
... detector support members, 11a to 11n ... backscattered electron detectors
12a-12n ... shielding cylinder

Claims (3)

[Claims] An electron optical system is provided for irradiating a target with each charged particle beam passing through an independent optical path, and secondary electrons generated by irradiating the target with each beam are generated. In a charged particle beam device in which a detector for detecting is provided exclusively for each charged particle beam, secondary electrons generated from the target by irradiation of another charged particle beam are mixed into the dedicated detector A charged particle beam device, comprising a member for blocking the radiation. 2. A plurality of columns having an electron optical system are provided, and a detector for detecting secondary electrons generated from a target by irradiation of a charged particle beam passing through each column is dedicated to each column. In the charged particle beam device provided in the above, a member for blocking secondary electrons generated from the target by irradiation of the charged particle beam passing through the other column from being mixed into the dedicated detector is provided. Characterized charged particle beam device. 3. The charged particle beam apparatus according to claim 1, wherein a negative potential is applied to the shielding member with respect to electrons from a target.