JP2002008577A - Electron microscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a high-speed sample replacement with an electron microscope for inspecting and observing silicon wafer for semiconductors. SOLUTION: A Z movement mechanism 4 is arranged inside a vacuum chamber 2, from which an already-observed sample 12 is moved sideways to take it out, and a standby sample 11 held by the Z movement mechanism 4 is moved downward and is placed on a sample stage 3. Also, an opening 21 for sending in a sample into the vacuum chamber 2 is separately provided above an opening 22 for taking out a sample. Further, a shield member 7 is provided between the Z movement mechanism 4 and the sample stage 3 free to move toward a sample-taking-out direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron microscope, and more particularly to an electron microscope for inspection and observation in a semiconductor device manufacturing field.

[0002]

2. Description of the Related Art Since a high throughput is required for an electron microscope for inspection and observation in the field of manufacturing semiconductor devices, techniques for speeding up sample exchange have been proposed in the past. For example, those described in JP-A-10-261377 and those described in JP-A-10-302699 correspond to this.

Japanese Patent Application Laid-Open No. Hei 10-261377 discloses a method in which a sample standby chamber having two separate sample standby positions is provided on the side of a vacuum chamber. By using this method, the sample to be exchanged can be prepared in one of the standby positions in advance, so that the sample exchange time can be reduced.

Further, in the apparatus described in Japanese Patent Application Laid-Open No. 10-302699, a feed arm is provided for transferring a sample from a standby position to a wafer holder for placing the sample on a sample stage, and transferring the sample from the wafer holder to the standby position. A method is disclosed in which a return arm is used to predict a transfer start command and perform control to move these arms to necessary positions in advance. According to this method, the time spent for the preparation operation of the feed arm and the return arm can be eliminated, so that the sample exchange time can be reduced.

[0005]

In recent years, electron microscopes have been widely used for inspection and observation in the field of manufacturing semiconductor devices. In the manufacture of semiconductor devices, there is a strong demand for improving the throughput of the device because the throughput, that is, the processing capacity per unit time of the device is directly related to the manufacturing cost.

In the inspection and observation process using an electron microscope, not only the time during which the sample is actually observed,
Since the sample exchange time also greatly affects the above-mentioned throughput, shortening the sample exchange time is an important technical issue.

In the method disclosed in Japanese Patent Application Laid-Open No. 10-261377, the sample to be exchanged can be prepared in another sample standby position in advance, so that the sample exchange time can be reduced. After placing the inspected / observed wafer, there is a problem that the sample stage must be moved to another sample standby position. In other words, extra time is required for moving the sample stage,
There is a limit to reducing the sample exchange time.

On the other hand, the method disclosed in Japanese Patent Application Laid-Open No. 10-302699 can eliminate the time spent for the preparation operation of the arm used for exchanging the sample, thereby shortening the time for exchanging the sample. However, with this method,
Since the time required for the sample to move from the wafer holder to the sample stage or vice versa is included in the sample exchange time, there is also a problem that the reduction of the sample exchange time is limited.

An object of the present invention is to solve these problems and to realize a structure of an electron microscope with a short sample exchange time.

[0010]

According to the present invention, in an electron microscope provided with a vacuum chamber, a sample stage, and a sample exchange device, a sample or a pallet on which a sample is fixed, which is installed inside the vacuum chamber, is moved downward. A Z-moving mechanism installed on the sample stage, a sample feeding mechanism for sending a sample or a pallet holding the sample from outside the vacuum chamber to the Z-moving mechanism, and a pallet holding the sample or the sample mounted on the sample stage A sample exchanging device is constituted by a sample take-out mechanism for moving the sample laterally out of the vacuum chamber.

In another aspect of the present invention, the sample is taken out of the vacuum chamber by the sample take-out mechanism by passing the opening of the vacuum chamber through which the sample is fed into the vacuum chamber by the sample feed mechanism. It is provided above the opening of the vacuum chamber through which it passes.

In still another embodiment of the present invention, a shield member is provided between the Z moving mechanism and the sample stage, the shield member being movable in the direction of feeding and taking out the sample.

The operation of the present invention will be described below. In order to shorten the sample exchange time in the electron microscope, it is effective to shorten the time from taking out the sample whose observation has been completed to placing the next sample on the sample stage. For this reason, generally, in an electron microscope for semiconductor observation aiming at high throughput, a method is adopted in which a sample standby position is provided near a sample outlet of a vacuum chamber and the next sample is standby. In this case, sample transport to the standby position
Since it can be performed while observing the previous sample in the vacuum chamber,
This is because the sample exchange time can be saved.

In the present invention, in order to make the time from the above-mentioned sample removal to the setting of the next sample as short as possible, FIG.
As shown in (1), a sample standby position is provided above a sample stage position for sample exchange in a vacuum chamber. The observed sample is moved laterally by the take-out mechanism and taken out, while the waiting sample is placed on the sample stage from above. This method allows for fast sample exchange without any waiting time to avoid mechanical interference.

In one embodiment of the present invention, the opening of the vacuum chamber for feeding the sample into the vacuum chamber and the sample for taking out the sample are not shared but are provided separately. Specifically, an opening for feeding the sample is provided above the opening for removing the sample. With this configuration, the above-described method of taking out the observed sample in the lateral direction and placing the standby sample on the sample stage from above can be performed more easily.

It is necessary to avoid the attachment of small dust or foreign matter having a size of several microns or less in the sample of the semiconductor element. However, since a mechanism for performing a moving operation such as a Z moving mechanism has a sliding portion, It is said that dust and foreign matter like this are easily generated. Further, since the inside of the vacuum chamber is kept at a vacuum, dust and foreign matter are rarely scattered by air and move in the horizontal direction, and it is considered that the dust or foreign matter falls directly below the place where the dust or foreign matter is generated. Therefore, if the Z moving mechanism is provided above the sample stage, there is a possibility that dust and foreign matter adhere to the sample.

In another embodiment of the present invention, a shield member is provided between the sample stage and the Z moving mechanism to prevent the above problem. This shield member is movable in the direction of taking out the observed sample so as not to be in the way of lowering the standby sample by the Z movement mechanism and placing it on the sample stage.
When removing the observed sample, the sample is simultaneously moved so as to cover the observed sample. With this structure, a sample exchange mechanism that does not contaminate the sample even when foreign matter or the like is generated from the sliding portion of the Z movement mechanism can be realized.

[0018]

FIG. 3 is a side view showing an electron microscope according to an embodiment of the present invention. The present embodiment has an object to be used for inspection and observation in a semiconductor manufacturing process, and has a function of using a silicon wafer as a sample without cutting it and performing observation as it is.

The entire electron microscope is composed of an electron optical system column 1,
It comprises a vacuum chamber 2, a sample stage mechanism 3, and a sample exchange mechanism including a Z moving mechanism 4, a sample feed mechanism 5, and a sample removal mechanism 6.

The Z moving mechanism 4 has a function of receiving and holding the sample sent by the sample feeding mechanism 6, moving the sample downward, and placing the held sample on the sample stage mechanism 3. In addition, the sample feeding mechanism 5 moves the sample to be observed next from the outside of the vacuum chamber 2 to the sample feeding opening 2.
1 to the vacuum chamber 2 and the Z moving mechanism 4
Has the ability to pass to Further, the sample removal mechanism 6
Has a function of taking out an observed sample from the sample stage mechanism 3 to the outside of the vacuum chamber 2 through the sample taking-out opening 22.

When the sample is to be exchanged, the standby sample 11 is sent by the sample feed mechanism 6 to the Z moving mechanism 4 in the vacuum chamber 2 through the feed opening 21 in advance, and is made to stand by. Since this step can be performed while observing the sample placed on the sample stage, it is irrelevant to the sample exchange time.

FIG. 4 shows a procedure for exchanging samples according to an embodiment of the present invention. In FIG. 4A, the sample 12 under observation is shown.
Is completed, the sample stage 3 moves to the sample exchange position as shown in FIG. Next, FIG.
As shown in (1), the observed sample 12 is taken out laterally through the take-out opening 22 by the sample take-out mechanism 6. As soon as the observed sample 12 is removed from the sample stage 3, the Z moving mechanism 4 places the standby sample 11 on the stage. Sample exchange is now complete.
As shown in FIG. 4D, the sample stage 3 moves to the observation position and starts observation of the sample. Next, as shown in FIG. 4E, the standby sample 11 is moved to the sample feeding mechanism 5 during the observation of the sample.
Is transferred to the Z moving mechanism 4 by using.

When such a structure is used, the observed sample 1
2 does not mechanically interfere with the standby sample 11,
Waiting sample 11 without waiting for handling of observed sample 12
Can be installed on the sample stage 3 immediately,
Sample replacement time can be greatly reduced.

FIG. 1 is a side view showing an electron microscope according to another embodiment of the present invention. The schematic structure of this embodiment is the same as that of the embodiment shown in FIG. 3, except that a shield member 7 and a shield moving mechanism 8 are provided in order to prevent sample contamination due to dust generation from the Z moving mechanism 4. Are different.

FIG. 2 shows a procedure for exchanging samples in this embodiment. 2A, when the observation of the sample 12 is completed, the sample stage 3 moves to the sample exchange position as shown in FIG. Next, as shown in FIG. 2C, the observed sample 12 is taken out laterally through the taking-out opening 22 by the sample taking-out mechanism 6. At this time, the shield member 7 also moves together in the sample removal direction at the same time.

As soon as the observed sample 12 is removed from the sample stage 3, the Z-movement mechanism 4 causes the standby sample 11 to move.
Is set on the stage. Thus, the sample exchange is completed, and the sample stage 3 moves to the observation position as shown in FIG. Thereafter, as shown in FIG. 2E, the shield member 7 is returned to the original position during the observation of the sample, and the next standby sample 11 is evacuated by the sample feeding mechanism 6 through the sample feeding opening 21. It is sent to the Z movement mechanism 4 in the chamber 2 and is kept on standby.

According to this structure, the sample exchange time can be greatly reduced, and even if dust is generated from the Z moving mechanism 4 provided above the sample stage 3, the sample can be prevented from being contaminated by the dust. .

[0028]

According to the present invention, it is possible to realize an electron microscope in which a sample can be exchanged in a short time.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an electron microscope according to one embodiment of the present invention.

FIG. 2 is a sectional view showing a procedure for exchanging samples according to one embodiment of the present invention.

FIG. 3 is a sectional view showing an electron microscope according to one embodiment of the present invention.

FIG. 4 is a sectional view showing a procedure for exchanging samples according to one embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electronic optical column, 2 ... Vacuum chamber, 3 ... Sample stage mechanism, 4 ... Z moving mechanism, 5 ... Sample feeding mechanism, 6 ...
Sample taking-out mechanism, 7: Shield member, 8: Shield moving mechanism, 11: Stand-by sample, 12: Observed sample, 21: Sample sending opening, 22: Sample taking opening.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshie Kurosaki 882 Ma, Hitachinaka-shi, Ibaraki Prefecture Within the Hitachi Measuring Instruments Group (72) Inventor Kazuo Aoki 882 Maomo, Hitachinaka-shi, Ibaraki Hitachi, Ltd. F-term in the Measuring Instruments Group of the Works (Reference) 5C001 AA01 AA02 CC01 CC04

Claims (3)

[Claims] 1. An electron microscope comprising a vacuum chamber, a sample stage, and a sample exchange device, wherein the sample exchange device comprises:
A Z-movement mechanism for moving a sample or a pallet on which the sample is fixed, which is installed inside the vacuum chamber, downward and installing it on the sample stage; A sample feeding mechanism for feeding a pallet with a fixed pallet, and a sample removal mechanism for laterally moving a sample or a pallet on which the sample is fixed on the sample stage and taking the sample out of the vacuum chamber. Electron microscope. 2. The electron microscope according to claim 1, wherein the opening of the vacuum chamber through which the sample is fed into the vacuum chamber by the sample feeding mechanism is provided.
An electron microscope, which is located above an opening of the vacuum chamber through which a sample is taken out of the vacuum chamber by the sample taking out mechanism. 3. The electron microscope according to claim 1, wherein a shield member is provided between the Z moving mechanism and the sample stage, the shield member being movable in a sample feeding and sample removing direction. An electron microscope to be characterized.