JPH05258702A - Sample holding mechanism - Google Patents

Abstract

PURPOSE:To provide a sample holding mechanism which enables sample replacement irrespective of a surrounding pressure and to enhance through put. CONSTITUTION:In the case of conveying, observing or beam drawing of a sample 51, a holding body 35 fixed to a tip of lever is pressed to a sample end face by means of a coil spring to hold the sample 51. In the case of sample replacement, a bar 38 is displaced by a pad plate 22 in the direction to push a lever, and the holding body 35 is separated from the sample end face against the coil spring to release holding of the sample 51.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sample holding mechanism such as a semiconductor wafer (hereinafter referred to as a wafer), and more particularly to a sample holding mechanism suitable for holding a sample such as a wafer in a vacuum.

[0002]

2. Description of the Related Art When observing a sample such as a wafer with a scanning electron microscope or an electron beam drawing apparatus or drawing an electron beam on the surface of the sample, a sample such as a wafer in the atmosphere is mounted on a sample table. A method of introducing this into a vacuum and observing or drawing a sample such as a wafer under vacuum is adopted.

As a conventional sample holding device of this type, as shown in Japanese Patent Laid-Open No. 167245/1985, a holding body for holding the sample end face mounted on a supporting member together with the holding member is provided at the tip. It has means for displacing due to a change in ambient pressure. As a displacement means, a metal bellows is used, and it is known that when the ambient pressure changes from atmospheric pressure to vacuum pressure, it is displaced to a position where the holder at the tip presses the sample end face.

[0004]

SUMMARY OF THE INVENTION In the above prior art,
The metal bellows is displaced when the sample exchange chamber is in a vacuum,
Since the holder presses the sample end surface, there is a problem that the sample exchange must be performed after the pressure in the sample exchange chamber is set to the atmospheric pressure.

An object of the present invention is to provide a sample holding mechanism capable of exchanging samples regardless of ambient pressure.

[0006] Another object of the present invention is to improve the throughput by achieving the above object.

[0007]

A feature of the present invention is that a lever having a coil spring is used as a pressing means for the sample holder, and a contact plate for displacing the holder is fixedly provided in the sample exchange chamber. ..

[0008]

When the sample is transported, observed or drawn, the holding body fixed to the tip of the lever presses the sample end surface by the coil spring to hold the sample. Also, when exchanging samples,
The bar causes the bar to be displaced in the direction of pushing the lever, the holder is separated from the sample end face against the coil spring, and the sample is released.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view of a sample exchanging device in a wafer observing device such as a scanning electron microscope including a sample holding mechanism according to the present invention, and FIG. 2 is a partial sectional plan view of a sample holding mechanism portion.
Is a vertical sectional view.

In FIG. 1, reference numeral 21 denotes a sample exchange chamber, which is closed or communicated with the sample chamber 11 in a vacuum by a partition valve 12.

Further, 31 is a base of the sample table, and a supporting member 33 for mounting the sample wafer 51 and a holding member 32 for holding the end surface of the wafer 51 are fixedly provided. Further, a lever 34 having a holder 35 for holding the end surface of the wafer 51 mounted on the supporting member 33 together with the holding member 32 at the tip is attached to the base 31 by a shaft 37.
The lever 34 has a tension spring 36, and
The end face of No. 1 is displaced in the direction of pressing.

The inside of the sample exchange chamber 21 is under vacuum pressure, and the base 3
1 is in the position shown in FIG.
At this time, the bar 38 pushes the lever 34, so that the holding body 35 is separated from the end surface of the wafer 51, and the wafer can be exchanged. In this state, the arm 28 provided in the sample exchange chamber 21 rotates and the already-observed wafer is transferred to the base 31.
To the base 41. Similarly, the arm 29 rotates to transfer the next observation wafer from the base 41 to the base 31.

The feed mechanism for moving the base 31 into and out of the sample chamber 11 is composed of a feed screw 23, a nut 25 fitted on the feed screw 23, and a straight guide 24, and the motor 26 located outside rotates the feed screw 23. The nut 25 is configured to move linearly along the linear guide 24. The nut 25 can chuck / unchuck the base 31, and carries the base 31 into and out of the sample chamber 11. The guide 24 for guiding the base 31 may be, for example, a sliding guide member made of a material such as tetrafluoroethylene resin, or a rolling guide member having ball bearings arranged therein.

When the base 31 is conveyed in the direction of the sample chamber 11, the bar 38 is separated from the contact plate 22, and the tension spring 36 causes the holder 35 to press the end surface of the wafer 51 to hold the wafer.

After the wafer is loaded into the sample chamber 11 from the sample exchange chamber 21 through the partition valve 12, the partition valve 12 is closed, the sample exchange chamber 21 is set to the atmospheric pressure, and the observed wafer on the base 41 is next observed outside. Replace with wafer. Sample exchange room 2 again
When 1 is evacuated and the observation of the wafer in the sample chamber 11 is completed, the partition valve 12 is opened and the base 31 is returned to the position shown in FIG.

According to the above sample exchange procedure, since another wafer is being observed while the wafer is being exchanged in the atmosphere, two wafers in total are provided in the sample exchange chamber 21 and the sample chamber 11. Exists. Therefore, the throughput is improved about twice as compared with the conventional case where wafers are transferred one by one from the atmosphere to the atmosphere again through the sample chamber.

In the above embodiment, as shown in FIGS. 4 to 5, the same effect as in the above embodiment can be obtained by using the bar 61 connected to the lever 37 by the shaft 62 instead of the bar 38. In this case, the problem of friction in the contact between the side surface of the lever 34 and the tip of the bar 38, which is a concern in the above embodiment, is solved.

Further, by adopting a coil spring 36 having a diameter smaller than that of the metal bellows conventionally used,
The base 31 can be thinned. This is effective for downsizing the sample transport mechanism.

[0019]

As described above in detail, according to the present invention, the sample can be exchanged in the sample exchange chamber by only moving the sample table regardless of the ambient pressure. Moreover, the throughput is improved by using this mechanism.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional plan view of a sample exchange device including a sample holding mechanism showing an embodiment of the present invention.

FIG. 2 is a partial cross-sectional plan view of a sample holding mechanism portion showing an embodiment of the present invention.

FIG. 3 is a vertical sectional view of a sample holding mechanism portion showing an embodiment of the present invention.

FIG. 4 is a partial cross-sectional plan view of a sample holding mechanism portion showing another embodiment of the present invention.

FIG. 5 is a vertical sectional view of a sample holding mechanism portion showing another embodiment of the present invention.

[Explanation of symbols]

11 ... Sample chamber, 12 ... Gate valve, 21 ... Sample exchange chamber, 2
2 ... Patch plate, 23 ... Feed screw, 24 ... Straight guide, 25
... nuts, 26 ... motors, 27 ... guides, 28,29 ...
Arms, 31, 41 ... Base, 32 ... Holding member, 33 ... Support member, 34 ... Lever, 35 ... Holding body, 36 ... Tension spring, 37, 62 ... Shaft, 38, 61 ... Bar, 51, 52 ...
Wafer.

Claims (2)

[Claims] 1. A sample table on which a sample such as a wafer is placed, a holder for holding an end face of the sample, a lever having the holder at its tip, and a holder attached to the lever. A sample holding mechanism comprising a spring for displacing the lever and a bar for pushing the lever and displacing the holder in a direction away from the end face of the sample against the spring. 2. A sample chamber that holds a vacuum state, a feed mechanism that moves the sample stage forward and backward in the direction of the sample chamber, and a sample exchange chamber that is shut off and communicated with the sample chamber via a gate valve. 2. The sample holding mechanism according to claim 1, further comprising a backing plate fixedly arranged to displace the holding body by pressing the lever mounted on the table.