JPS5812700B2 - electron beam equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electron beam device such as an electron microscope or an X-ray microanalyzer.

In general, in electron microscopes and the like, in order to quickly exchange samples, a preliminary chamber is provided adjacent to the sample chamber and separated by an air lock valve, and the sample is taken in and taken out from the atmosphere through the preliminary chamber.

That is, a so-called air lock method is adopted in which the preliminary evacuation chamber is evacuated by a roughing pump such as an oil rotary pump, and then an air lock valve is opened to send the sample into a sample chamber which is constantly maintained in a vacuum.

In this case, since the ultimate pressure by the oil rotary pump is relatively high (e.g. 10-3 Torr), after evacuating the preliminary chamber with the oil rotary pump, the air lock valve is opened to directly communicate with the sample chamber maintained at a high vacuum of about 10-6 Torr. Then, gas molecules from the preliminary chamber flow into the sample chamber, causing sample contamination.

Furthermore, gas molecules adhering to the sample exchange rod and the surface of the sample in the preliminary chamber cannot be sufficiently exhausted, increasing sample contamination.

Furthermore, the gas molecules that have flowed into the sample chamber also flow into the electron gun chamber through the exhaust pipe, resulting in the inconvenience of damaging the electron source (emitter).

By the way, recently, in order to solve such problems, the pressure in the preliminary chamber can be evacuated to approximately the same level as the pressure in the sample chamber by connecting a high vacuum pump such as an oil diffusion pump or an ion pump to the preliminary chamber. Devices have also been proposed that allow this to occur.

However, in such an apparatus, a new high vacuum exhaust system must be installed near the sample chamber, which may make it difficult to attach various attachments.

Furthermore, the entire exhaust system becomes complicated, which causes an increase in cost, and also causes other inconveniences such as vibration.

The present invention is intended to solve such inconveniences, and will be explained in detail below with reference to the drawings.

The attached drawings are schematic diagrams showing an embodiment of the present invention, and 1
is the mirror body of an electron microscope.

Inside the mirror body, an electron gun chamber 2, a focusing lens 3, a sample chamber 4, an objective lens 5, a projection lens 6, an observation chamber 7, and a camera chamber 8 are installed in order. and observation room 7 communicating with camera room 8 are main exhaust pipes 9a and 9, respectively.
The air is evacuated by separate high-vacuum pumps 10a and 10b such as oil diffusion pumps and ion pumps via b.

This is to prevent gas molecules generated within the camera chamber 8 from flowing into the sample chamber or electron gun chamber through the main exhaust pipe.

At this time, since the magnetic pole piece of the imaging lens and the diaphragm are placed on the electron beam path inside the mirror body, the exhaust conductance between the sample chamber 4 and the observation chamber is very small, and therefore, the exhaust conductance between the sample chamber 4 and the observation chamber is very small. The flow of gas molecules into the sample chamber through the electron beam path is negligible.

Reference numeral 11 denotes a preparatory chamber communicating with the sample chamber 4, and an air lock valve 12 is installed at the boundary between the preparatory chamber and the sample chamber to shut off both chambers under vacuum.

The preliminary chamber is communicated with the observation chamber through an exhaust pipe 14 equipped with a valve 13, and a sample chamber (not shown) is provided in the preliminary chamber to transport the sample placed in the preliminary chamber to the sample chamber. Built-in exchange mechanism.

15 is a roughing pump such as an oil rotary pump for roughing the inside of the preliminary chamber 11 via the exhaust pipe 16; 17 is a valve provided in the exhaust pipe 16; and 18 is a pump for making the inside of the preliminary chamber 11 atmospheric. It is a leak valve for.

When inserting a speculum sample into the sample chamber 4, the air lock valve 12, valves 13 and 17 are closed, and the leak valve 18 is opened to bring the preliminary chamber 11 to atmospheric pressure.

In this state, a lid (not shown) provided in the preliminary chamber is opened, the sample is placed in a predetermined position in the preliminary chamber, and then the lid is closed again.

Next, the valve 17 is opened and the preliminary chamber 11 is pumped by the roughing pump 15.
is evacuated to a pressure of approximately 0.1 Torr.

Thereafter, the preliminary chamber 11 is communicated with the observation chamber 7 by closing the valve 17 and then opening the valve 13.

At this time, the observation chamber 7 is kept at a high vacuum (approximately 10-5 Torr) and its volume is extremely large compared to the preliminary chamber 11, so the gas molecules in the preliminary chamber are quickly diffused into the observation chamber and diluted. Within a short time, the pressure in the preliminary chamber is 1
It reaches the order of 0-5 Torr.

Thereafter, the valve 13 is closed, the air lock valve 12 is opened, the sample is moved to the sample chamber 4 by a sample moving mechanism (not shown), and the air lock valve 12 is closed again.
The pressure immediately reaches the required level, for example, about 10-7 Torr.

In this embodiment, when oil diffusion pumps are used as the high vacuum pumps 10a and 10b, the back pressure side of the oil diffusion pump that exhausts the sample chamber 4 etc. is evacuated by the other oil diffusion pump that exhausts the observation chamber 7. It may be configured as follows.

Also, we have described the case where the preliminary room is connected to observation room 7,
It could also be a camera room.

By configuring as described above, the present invention can evacuate the preliminary chamber to a high vacuum without newly connecting a high vacuum pump to the preliminary chamber as in the past, so various attachments can be easily attached, and The exhaust system can be simplified, costs can be reduced, and the influence of vibration can be reduced.

Furthermore, since the volume of the observation chamber connected to evacuate the preliminary chamber to high vacuum is extremely large compared to the volume of the preliminary chamber, even if the pressure in the preliminary chamber 11 caused by the roughing pump 15 is high, the preliminary chamber can be evacuated within a short period of time. The pressure reaches high vacuum.

This can reduce the evacuation time by the roughing pump, thereby reducing the amount of oil vapor flowing back into the preliminary chamber from the oil rotary pump as a roughing pump.

It should be noted that the above description is an illustration of the present invention, and many modifications can be made in implementing the present invention.

For example, in the above-mentioned embodiments, an electron microscope has been described, but the present invention is not limited thereto, and can also be implemented with, for example, an X-ray microanalyzer.

That is, in an X-ray microanalyzer, a spectroscopic crystal is used to disperse the energy of characteristic X-rays generated by irradiating a sample with an electron beam, and this spectroscopic crystal is formed adjacent to the sample chamber in which the sample is mounted. placed in a spectroscopic chamber.

At this time, the spectroscopic chamber and the sample chamber are vacuum-blocked by an X-ray extraction window having a mylar film provided at the boundary between the spectroscopic chamber and the sample chamber.

Therefore, if the spectroscopic chamber and the preliminary chamber provided in the sample chamber are connected by an exhaust pipe having a valve, the same effect as described above can be obtained.

[Brief explanation of the drawing]

The accompanying drawings are schematic diagrams showing an embodiment of the present invention. In the figure, 1 is the mirror body of the electron microscope, 2 is the electron gun chamber, 3 is the focusing lens, 4 is the sample chamber, 5 is the objective lens, 6 is the projection lens, 7 is the observation chamber, 8 is the camera chamber, 9a, 9b, 14 and 16 are exhaust pipes, 10a and 10b are high vacuum pumps,
11 is a preliminary chamber, 12 is an air lock valve, 13 and 17 are valves, 15 is a roughing pump, and 18 is a leak valve.

Claims (1)

[Claims] 1 a sample chamber, a first high vacuum evacuation means for evacuating the sample chamber, and a second chamber connected to the sample chamber via an electron beam passage hole and having a larger evacuation space than the sample chamber; a second high vacuum evacuation means for evacuating the second chamber; a preliminary chamber attached to the sample chamber so as to be able to communicate through an air lock valve; and a roughing pump for roughing the preliminary chamber. An electron beam apparatus comprising: an exhaust pipe for connecting the preliminary chamber and the second chamber; and a vacuum valve provided on the exhaust pipe.