JPH0551136B2 - - Google Patents

Description

[Detailed Description of the Invention] [Summary] The present invention relates to a secondary electron detector, which detects secondary electrons generated by an electron beam irradiated onto a sample by an electron beam device, etc. When detecting secondary electrons with the detection means, the high voltage supplied to the scintillators of the plurality of detection means is supplied all at once using a ring-shaped electrode, thereby facilitating inspection and replacement of the detection means.

[Industrial application field]

TECHNICAL FIELD The present invention relates to a secondary electron detector, and particularly to a secondary electron detector.
The present invention relates to a secondary electron detector used in an electron beam device or the like, which performs quantitative measurements by disposing a detection means for detecting secondary electrons in a plane parallel to a sample surface irradiated with an electron beam.

In an electron beam apparatus, a secondary electron detector used to detect secondary electrons generated by an electron beam irradiated onto a sample is often inspected for replacement. There has been a demand for such a secondary electron detector that is easy to replace and inspect.

[Conventional technology]

In electron beam devices, such as electron beam testers or current-flowing electron microscopes, which perform quantitative measurements, a sample is irradiated with an electron beam, and the secondary electrons emitted from the sample are detected by a secondary electron detector. Ta.

In this case, one secondary electron detector was used, but recently, as shown in FIG.
The secondary electrons 3 emitted from the sample were added to a scintillator 4, passed through a light pipe 6, and multiplied by a photomultiplier tube 7, thereby converting them into electronic signals.

Secondary electron detector 2a for detecting secondary electrons
As for the configuration of ~2d, the through hole 11 is
Secondary electrons are incident on the scintillator 4, which is placed opposite to the scintillator 4. A scintillator electrode 8 for receiving secondary electrons 3 is provided on the outer periphery of the scintillator 4, and a wire 10 connected to this electrode for applying a high voltage of about 10 Kv is connected to one high voltage introduction terminal 9.

A light pipe 6 is placed on the opposite side of the scintillator 4 to the opposing through hole 11, receives the secondary electrons incident on the scintillator 4, emits light, and transmits this optical signal through the light pipe 6 to a photomultiplier tube 7. The electrical signal is extracted by multiplying the Normally, a voltage of about -200 to 500V is applied to the collector electrode 5.

[Problem that the invention seeks to solve]

In the secondary electron detector having the above-mentioned conventional configuration, the chamber 1 is kept in a vacuum, but since a plurality of wires 10 for supplying high pressure are routed within the vacuum vessel, the number of wires becomes large and long. Also, 2
When replacing the next electron detectors 2a to 2d, particularly the scintillators, etc., the wire 10 must be removed from the scintillator electrode 8 inserted into the collector electrode 5. However, it is very complicated to remove the wires 10 of the plurality of secondary electron detectors within the narrow chamber 1. These things apply not only to replacement but also to inspection, etc.

In addition, since the collector electrode 5 covers the scintillator electrode 8 and the scintillator 4, the scintillator 4
It had the disadvantage that replacing and inspecting it became more and more troublesome.

This invention has been developed in view of the above-mentioned drawbacks of the present invention, and its purpose is to provide a secondary electron detector that can be extremely easily maintained, inspected, and replaced.

[Means for solving problems]

As shown in FIG. 1, the secondary electron detector of the present invention has a scintillator 4 having a scintillator cap 23 functioning as a scintillator electrode 8, and a secondary electron detector having a photomultiplier tube 7 on the opposite side of a light pipe 6 disposed facing the scintillator 4. A plurality of detection means 12a to 1 for detecting electrons
2d is placed in the scintillator cap 23 so as to face the through hole 16 made in the cylindrical part of the cylindrical collector electrode 14 through which the electron beam 15 passes through the cylindrical center part.
A high voltage (10Kv) is applied through the ring 13 so that the scintillator 4 and the like can be easily replaced.

[Effect]

In the secondary electron detector of the present invention, a plurality of detection means 12a to 12d of the present invention are inserted into through holes 1a to 1d (FIG. 2) bored in a chamber 1, and a common ring 13 is inserted into a groove 17 within the chamber. The wire 1 can be supplied with high pressure just by dropping it into the container and pressing it with a spring etc.
By setting it to 0, maintenance of the scintillator becomes easy.

〔Example〕

The secondary electron detector of the present invention will be described in detail below with reference to FIGS. 1 to 5 a, b, and c.

Although the electron beam device of the present invention is not shown, the electron beam emitted from the electron gun is placed in a vacuum chamber 1.
At the final stage, the light is focused onto a sample 19 by an objective lens coil 18 forming an objective lens.
Secondary electrons 3 emitted from the sample 19 by electron beam irradiation are transmitted through the through hole 1 formed in the cylindrical collector electrode (focusing grid) 14 of the present invention.
6 and enters the scintillator 4 of the detection means 12a to 12d.

As shown in FIG.
A number of through holes 16 are bored in the outer peripheral surface of the cylindrical portion 22 so as to face each other. One side of the cylindrical portion 22 is closed with a flange portion 20, and a through hole 21 is bored in the center of the flange portion 20 through which the electron beam 15 passes. The through hole 21 may be small enough to allow the electron beam 15 to pass through. In this way, unnecessary secondary electrons reaching the scintillator 4 from above can be absorbed. A voltage of about -200V to 500V is applied to this collector electrode.

The configuration of the plurality of detection means 12a to 12d arranged opposite to the cylindrical collector electrode 14 is as shown in FIG. That is, the scintillator 4 is 2
When the next electron 3 is incident, it is converted into light and transmitted through the light pipe 6 to the electron multiplier 7 (see FIG. 1) as shown by arrow B.

For this purpose, the scintillator 4 is brought into contact with the light pipe 6 on the side opposite to the photocathode, and a female thread 25 provided on the inner periphery of the scintillator cap 23 is screwed into a male thread 26 provided on the outer periphery of the tip of the light pipe 6. At the same time, the scintillator 4 is brought into contact with the end surface of the tight pipe 6.

The scintillator cap 23 serves as the scintillator electrode 8, and is composed of a U-shaped metal cap, and an opening 24 is bored in the front lid portion 23a.
The secondary electrons 3 that have passed through the through hole 16 of the cylindrical collector electrode 14 and the opening 24 of the scintillator cap 23 are incident on the scintillator 4.

Although not shown in FIG. 3, a flange 27 is fitted in the middle of the light pipe 6 as shown in FIG. electron multiplier tube 7
and the flange 27 are covered.

Through holes 1a to 1d are bored in the chamber 1 constituting the electron lens barrel at four equal positions on the circumference, a disc-shaped insulating member 29 is fixed inside the lens barrel, and a cylindrical collector electrode 14 is provided in the center. A center hole 31 into which the cylindrical portion 22 can be inserted is bored, and four through holes 30 penetrating from the outer periphery toward the center hole 31 are formed at the center position in the thickness direction of the disc-shaped tax salt member 29 at positions dividing the circumference into four equal parts. The drilled through holes 30 are the through holes 1a to 1d drilled in the lens barrel.
Matches the position.

The tips of the detection means 12a to 12d described above are inserted into the through holes 1a to 1d and the through hole 30. In addition, 32 is an O-ring placed in the through holes 1a to 1d to connect the chamber 1.
Airtightness between the detection means and the detection means is maintained. Flange 2
7 is integrated with the detection species, so chamber 1
It is integrated with the chamber by fixing it to the outer wall of the chamber with screws 33. The insulating member 29 has a cylindrical groove 17.
is formed to have the same diameter as the ring 13, and the ring 13 is inserted into the groove 17. The depth of the groove 17 at the portion in contact with at least four scintillator caps 23 reaches the outer peripheral surface of the scintillator cap 23. If the depth of the groove 17 is made uniform until it reaches the scintillator cap 23, there is no need to provide a convex portion 34 as shown in FIG. A ring 13 with a flat bottom as shown in FIG. 5b can be used. In this case, by forming a part of the lower surface of the ring 13 into a tapered surface 35, as shown in the cross section of FIG. The ring 13 is connected to the high voltage introduction terminal 9 which is airtightly attached to the chamber 1. Furthermore, the ring 13 is electrically connected by being pressed to the scintillator cap 23 within the groove 17 via a spring or the like (not shown). ing. Further, if the springiness of the ring 13 itself is utilized, a spring is not necessary.

Since the secondary electron detector of the present invention is constructed as described above, when inspecting or replacing it, it is only necessary to take out the ring from the groove and pull out the detection means from the through hole drilled in the chamber. It became possible to exchange.

〔Effect of the invention〕

Since the present invention is constructed and operates as described above, in case of scintillator failure or inspection of the detection means, the detection means can be easily pulled out by simply removing the ring, and there is no need to route long wires inside the chamber. It has many characteristics of

[Brief explanation of drawings]

FIG. 1 is a plan view of the secondary electron detection device of the present invention;
Fig. 2 is a cross-sectional view taken along line A-A' in Fig. 1, Fig. 3 is a partially enlarged side sectional view of the secondary electron detection means used in the present invention, and Fig. 4 is a perspective view of the collector electrode used in the present invention. Figures 5a and 5b are perspective views showing the appearance of the ring used in the present invention, Figure 5c is a sectional view of the ring of the present invention, and Figure 6 is a plan view of a conventional secondary electron detector. . 1...Chamber, 2a-2d...Secondary electron detector, 4...Scintillator, 5...Collector electrode, 6...Light pipe, 7...Photomultiplier tube,
8...Scintillator electrode, 9...High voltage introduction terminal, 10...Wire, 12a to 12d...Detection means, 13...Ring, 14...Cylindrical collector electrode, 16...Through hole, 17...Groove , 23... scintillator cap, 29... insulating member.

Claims (1)

[Scope of Claims] 1. A cylindrical collector electrode 14 having a plurality of openings provided opposite to the outer circumferential surface, and a light pipe opposite to a scintillator 4 having a scintillator electrode and facing the openings. A plurality of detection means 12a, 12b, 12 for detecting secondary electrons having a photomultiplier tube 7 on the surface
c, 12d; and a ring-shaped electrode 13 that collectively supplies high voltage to the scintillator electrodes of the plurality of detection means.