JPS6034785B2 - Sample exchange device for electron beam equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sample exchange device for an electron beam apparatus, and more particularly to an improvement of vacuum leak means into the sample exchange device.

Recently, a technology has been developed to draw fine and precise patterns on the surface of a semiconductor sample using an electron beam. However, if dust or metal powder adheres to the sample using this electron beam drawing device, that part will be exposed to the electron beam. Since it is blocked, it is not drawn and becomes a defective product.

Even if such adhered particles are extremely small, on the order of 0.1 French, they can become a problem, and therefore sufficient care must be taken. Such electron beam equipment is equipped with a sample exchange chamber connected to the sample chamber where the sample is processed, and after performing predetermined preliminary processing in the sample exchange chamber, the sample is introduced into the sample chamber by opening the sample introduction valve. . That is, the sample exchange chamber is evacuated until a predetermined degree of vacuum is reached after a sample is placed in the sample introduction device. At this time, of course, the sample is cleaned, and in particular, the sample exchange chamber is cleaned to prevent dust from adhering to the surface. However, since the sample exchange chamber is provided with a sample introduction valve and a mechanism for moving the sample horizontally and vertically, it is impossible to completely eliminate the generation of metal powder and dust from these mechanisms. Therefore, when air is rapidly introduced into the sample exchange chamber to cause a leak, the introduced air blows up dust and the like in the sample exchange chamber and deposits it on the cleaned sample. Conventional leak valves pose such a risk because they cannot control the leak rate. Further, in some cases, the closing area of the leak valve is made smaller in order to slow down the leak speed, but this increases the time required for the leak to occur, which is not practical.
The conventional method was to insert the sample into the sample exchange chamber after injecting the IJ with the leak valve and waiting until the suspended particles settled down, but this greatly reduced the operating rate of the device.

Furthermore, in this case, undrawn samples must be inserted into the sample exchange chamber one by one, which further reduces the operating rate. The purpose of the present invention is to provide a sample exchange device for an electron beam device that can obtain high-quality products with high efficiency. The reason is that the leak speed of the leak valve is controlled by the output signal.

FIG. 1 is a system diagram of a sample exchange device which is an embodiment of the present invention.

A sample introduction valve 4 is installed between the sample chamber 1 and the sample exchange chamber 2, and by pushing the sample 3a, which has been re-placed on the vertical mechanism 6 in the sample exchange chamber 2, with the transfer mechanism 5, The sample can be introduced into the sample chamber 1 via the sample introduction valve 4 . Further, the other sample 3b on the vertical mechanism 6 is introduced into the sample chamber 1 after the sample 3a is processed and pulled out, and processed in the same manner. After performing electron beam lithography on the two samples 3 in this way, close the valve 7 provided in the exhaust passage of the vacuum exhaust device 8 that was evacuating the inside of the sample exchange chamber 2, and then open the leak valve. The valve 11 is gradually opened to return the inside of the sample exchange chamber 2 to atmospheric pressure, and the upper lid is opened to take out the processed sample 3. The above operations are the same as those of conventional sample exchange devices, but in the device of this embodiment, in order to rationally open the leak valve 11 and control the degree of vacuum in the sample exchange chamber 2, the following steps are performed. We have put in place measures to

That is, a vacuum gauge 18 is installed in the sample exchange chamber 2, and its output signal is connected to the processing device 17 via a vacuum detection circuit 19. Further, an output signal from a leak detector 12 attached to the leak valve 11 is supplied to a processing device 17 via a leak detection circuit 13. The processing device 17 that inputs and calculates the detection signals of the operating states of the vacuum gauge 18 and the leak valve 11 in this way outputs them to the control circuit 16 and outputs them to the transmitting circuit 1.
5 generates a signal, and the opening period of the electromagnetic valve 10 is adjusted by the output of the drive circuit 14. Solenoid valve 10 is air source 9
The compressed air is sent to the air cylinder of the leak valve 11, and the amount of leakage is adjusted by changing the degree of opening of the leak valve 11. The sample exchange device configured in this way is
By setting the leak rate so that air leaks into the sample exchange chamber 2 does not stir up dust in the chamber, the leak state of the leak valve 11 can be detected by the leak detector 1.
2 and the vacuum gauge 18, the pressure inside the sample exchange chamber 2 can be automatically raised to atmospheric pressure.

In this way, an extremely small amount of air is introduced at the beginning of the leak, but as the pressure rises, the amount introduced can be increased to reach atmospheric pressure in a short time, improving the experimental efficiency of this sample exchange device. can be done. Now, if the closed area of the leak valve 11 is S, the atmospheric pressure is P, and the pressure inside the container is P2, then the leak rate of this leak valve 11 is S(
P, - P2).

Therefore, since the pressure inside the sample exchange chamber 2 gradually increases as P2 increases by introducing air, even if the entrance area of the leak valve 11 is increased by the amount that P2 increases, the leak rate is not affected. That is, by experimentally determining in advance a leak rate that does not cause particles in the sample exchange chamber 2 to fly up, and controlling the entrance area of the leak valve 11, it is possible to exchange samples without causing defects. The above solenoid valve 10
The leak valve 11 is opened intermittently by a pulse current generated by a processing device 15 using a microcomputer or the like.
The opening degree is adjusted.

The leak valve 11 does not operate when the pulse frequency is high, but when the frequency decreases, it operates in the middle of the air cylinder's full stroke, for example, at 1/10, 1/5, etc., and the leak valve becomes half open accordingly. , the opening area of the valve is changed by changing the frequency. Note that the leak valve 11 shown in FIG. 1 may be the same as that conventionally used. The sample exchange device of this example is as follows:
The efficiency of sample exchange can be improved by introducing air through the IJ leak valve 11 at a leak rate that does not cause dust or the like to fly up inside the sample chamber while detecting the pressure inside the sample exchange chamber. can.

Moreover, effects such as being able to accommodate a plurality of samples in the sample exchange chamber and increasing experimental efficiency can be obtained. In the above embodiment, compressed air was introduced into the air cylinder to operate the leak valve 11, but the same effect can be obtained by adjusting the rotation of a commonly used needle slow leak stool using a pulse motor.

Note that a servo motor or a motor with a constant rotation speed may be used instead of the pulse motor. In this case, since the process is performed electrically without using compressed air, the configuration is even simpler. The sample exchange device of the electron beam apparatus of the present invention improves experimental efficiency by shortening the leak time for introducing air into the sample exchange chamber, and efficiently processes high-quality processed samples without causing dust or the like to adhere to the sample. You can get the effect that you can.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a sample exchange device which is an embodiment of the present invention. 1...Sample room, 2...Sample exchange room, 3
...Sample, 4...Sample introduction valve, 5
...Transfer mechanism, 6...Vertical mechanism, 7...
・・・Valve, 8...''・Vacuum exhaust layer, 9...
...Air source, 10...Solenoid valve, 11...
Leak valve, 12... Leak detector, 13... Leak detection circuit, 14... Drive circuit, 15... Transmission circuit, 16... Control circuit, 17...・・・・・・
Processing device, 18... Vacuum gauge, 19...
Vacuum detection circuit.

Claims (1)

[Claims] 1 In a sample exchange device for an electron beam device having a sample exchange chamber that communicates with the sample chamber via a sample introduction valve, communicates with the vacuum exhaust device via a valve, and is equipped with a leak valve and a sample transfer mechanism, the above-mentioned A sample exchange device for an electron beam apparatus, characterized in that the leak rate of the leak valve is controlled by an output signal indicating the degree of vacuum from a vacuum gauge installed in the sample exchange chamber.