JPH04129147A - Charged particle ray device - Google Patents

Abstract

PURPOSE:To easily maintain the proper degree of vacuum in a lens barrel by providing an evacuation device in such a way as to bypass space formed around an objective lens for inclining a sample. CONSTITUTION:An electron beam after a hole at the lower ends of objective lenses 1, 2 and 3 reaches a sample 9 via the holes 7 and 6 of an evacuation tube (evacuation tube device) 4. Reflective electrons or secondary electrons are generated at the sample 9 and travel toward a detector 8, while ionizing gas molecules in a sample chamber 5. As a result, electrons generated due to the ionization of gas in the sample chamber 5 reach the detector 8, in addition to the reflective or secondary electrons from the sample 9. Consequently, secondary electrons are amplified by the gas molecules in the sample chamber 5. In this case, space covering an area where an electron beam emitted through an opening at the objective lenses 1, 2 and 3 comes in contact with the sample 9, is via the evacuated tube 4 and, therefore, the degree of vacuum in a lens barrel can be effectively restrained, regardless of the introduction of gas into the sample chamber 5.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a charged particle beam apparatus having a conical or truncated conical objective lens in order to secure a space for tilting a sample in a sample chamber.

[Conventional technology]

This type of charged particle beam device has a conical or truncated conical objective lens, which provides a wide space around the objective lens, allowing the sample to be tilted within the sample chamber. When the tilt angle of the sample is increased, the angle of the cone becomes smaller, and the space around the objective lens becomes thicker.

[Problem to be solved by the invention]

In the conventional technique as described above, the vacuum level inside the lens barrel connected to the sample chamber cannot be maintained well, so there is a problem that the pump configuration connected to the lens barrel becomes [i]. SUMMARY OF THE INVENTION An object of the present invention is to provide a charged particle beam device that can easily increase the degree of vacuum inside a lens barrel with a simple pump configuration.

[Means to solve problems]

In order to solve the above problem, the present invention as set forth in claim (1) includes:
In order to secure a space for tilting the sample (9) in the sample chamber (5), in a charged particle beam device having a conical or truncated conical objective lens (1, 2, 3),
, 2.3) The charged particle beam emitted from the aperture of sample (9)
An exhaust device (4) is installed around the objective lens (l, 2.3) and around the sample (9).
), and the present invention according to claim (2) is characterized in that a space for tilting the sample (9) is provided in the sample chamber (5). A conical or truncated conical objective lens (l, 2.3
) in the charged particle beam device having the sample chamber (5);
A gas introduction device (5a, 5b) is provided to introduce low-pressure gas into the space, and the space until the charged particle beam emitted from the aperture of the objective lens (l, 2.3) contacts the sample (9) is evacuated. The exhaust device (4) is connected to the objective lens (1,
2, 3) and is provided outside of the sample (9) while avoiding a space for tilting the sample (9), the present invention according to claim (3) ) or (2), in the charged particle beam device, the exhaust device has a space for the charged particle beam from the sample to travel;
The charged particle beam apparatus is characterized in that a small room portion is formed to secure a space for arranging a detector for the charged particle beam.

[Effect]

In the invention described in claims (1) and (2), an exhaust device is provided in the space around the objective lens, and the space until the charged particle beam emitted from the aperture of the objective lens comes into contact with the sample is evacuated. This can prevent the degree of vacuum inside the lens barrel connected to the sample chamber from decreasing from the sample chamber side.

Therefore, a complicated pump configuration is not required to maintain a good degree of vacuum inside the lens barrel. Further, since the exhaust device of the present invention is disposed in a space around the objective lens that has not been used conventionally, there is no need to make the charged particle beam device particularly large.

Furthermore, in the invention set forth in claim (3), the exhaust device has a small room for securing a traveling space for the charged particle beam from the sample and for securing a space for arranging a detector for the charged particle beam. Since a part is provided, charged particle beams from a sample can be detected without any problems even though an exhaust device is provided.

〔Example〕

FIGS. 1(a) and 1(b) show an E S EM-Environmental device, which is an embodiment of the charged particle beam device of the present invention.
Scanning l! 1electro+s Micro
Scopy (a microscope that uses low-pressure gases such as water vapor and nitrogen into the sample chamber, and utilizes the electron amplification effect by ionizing these gases with reflected electrons and secondary electrons from the sample)... FIG. 2 is an explanatory diagram of the vicinity of the objective lens.

FIG. 1(a) is a cross-sectional view (A-A' arrow sectional view in FIG. 1(b)), and FIG. 1(b) is a cross-sectional view taken along B-B in FIG. 1(a).
'It is a sectional view taken in the direction of arrows.

In Figures 1(a) and (b), the objective lenses are upper pole 1, lower pole 2,
It consists of a coil 3 and is designed in the shape of a truncated cone so that the sample can be tilted up to about 60 degrees. An exhaust pipe 4 for exhaust is provided outside the lower pole 2 of the objective lens. Drain pipe 4
As shown in FIGS. 1(a) and (b), in order to secure a space for tilting the sample, the detector 8 to which a positive voltage is applied is
In order to secure a space for the secondary electrons to travel up to the detection 3, the first small chamber 4a (corresponding to the former) is provided in the direction (Y direction) perpendicular to the exhaust direction (X direction).
This exhaust pipe 4, which serves as the second small chamber part 4b (corresponding to the latter), is provided with a hole 7 (on the sample side) and a hole 7 (on the objective lens side) through which the electron beam passes. It is being These holes 6 and 7 are used to obtain low magnification SEM images, so hole 7 is
- Medium, hole 6 has a size of 21 medium. This drain pipe 4
The exhaust conductance of is almost determined by the narrowest space 10,
A rotary pump (not shown) connected to the end of the exhaust pipe 4 is sufficient to achieve the purpose. The sample chamber 5 is evacuated through pipes 5a and 5b, and low-pressure gas such as water vapor and nitrogen is introduced into the sample chamber 5. A sample 9 is introduced into the electron beam irradiation position of the sample chamber 5 by a transport device (not shown). The transfer device is a known device including a transfer arm (not shown) and a moving stage.

Here, the function of the exhaust pipe 4 is as follows. That is, if the exhaust conductance of the small hole 6.7 and the exhaust port 10 in FIG.

Pea-PBX G.

Since the exhaust conductance is almost proportional to the opening area, G, - is -π・1", G+a-K・2×5×π
×4 (where K is a constant determined by the type of gas, etc.), then C,1 ζ G,. It becomes 40.

That is, the pressure between holes 6.7 is 1/40 of the sample chamber pressure.

Therefore, compared to the conventional ESEM, the vacuum inside the lens barrel can be increased to 1,740 degrees. Alternatively, it can operate at 40 times higher pressure with the same vacuum inside the lens barrel. Or, from another perspective, the capacity of the exhaust pump for exhausting the lens barrel can be increased to 1740.

With such a configuration, the electron beam exiting the hole at the lower end of the objective lens 1.2.3 passes through the hole 7.6 in the exhaust tube 4 and reaches the sample 9. Reflected electrons and secondary electrons are generated from sample 9,
These electrons head toward the detector 8 while ionizing gas molecules within the sample chamber 5 .

As a result, in addition to the reflected electrons and secondary electrons from the sample 9, electrons generated by ionization within the sample chamber 5 also reach the detector 8. As a result, secondary electron amplification is performed by gas molecules in the sample chamber 5 (USP 47
851B2).

At this time, the inside of the lens barrel must be maintained at a high vacuum, but the space before the electron beam emitted from the aperture of the objective lens 1.2.3 comes into contact with the sample is evacuated by the exhaust pipe 4. Even though gas is introduced into the sample chamber 5, the degree of vacuum inside the lens barrel can be effectively suppressed.

Furthermore, if you want to tilt the sample 9, you can do so using the space inside the sample chamber 5 formed outside the first small chamber 4a of the drain pipe 4.The sample 9 can only be tilted in one direction. It is enough.

〔Effect of the invention〕

The present invention improves the degree of vacuum inside the lens barrel by providing an exhaust device in a space outside the conical or truncated conical objective lens, which has not been used for any purpose in the past. Alternatively, if the degree of vacuum is the same, it will work even if the degree of vacuum in the sample chamber is increased. From another point of view, the ability of the pump to exhaust the lens barrel may be low.

In addition to the ESEM, the present invention is also applicable to an apparatus that processes a sample or performs selective deposition by introducing a reactive gas into a sample chamber.

Furthermore, it is also effective when no gas is introduced into the sample chamber.

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) are diagrams showing an embodiment of the present invention, and FIG. 1(a) is a cross-sectional view of the embodiment (A in FIG. 1(b)).
- A'' arrow sectional view), Figure 1 (b) is B of Figure 1 (b)
-B' arrow sectional view. [Explanation of symbols of main parts] 4... Exhaust pipe, 4a, 4b... Slit portion.

Claims (3)

[Claims] (1) To secure space for tilting the sample in the sample chamber,
In a charged particle beam device having a conical or truncated conical objective lens, an exhaust device is provided around the objective lens and in the space up to the point where the charged particle beam emitted from the aperture of the objective lens contacts the sample. A charged particle beam device characterized by being provided to avoid a space for tilting a sample. (2) To secure space for tilting the sample in the sample chamber,
In a charged particle beam device having a conical or truncated conical objective lens, a gas introduction device is provided for introducing low-pressure gas into the sample chamber, and the charged particle beam ejected from the aperture of the objective lens contacts the sample. An exhaust system that exhausts the space of
A charged particle beam device characterized in that it is provided outside the objective lens and away from a space for tilting the sample. (3) In the charged particle beam device according to claim (1) or (2), the exhaust device secures a traveling space for the charged particle beam from the sample and is provided with a detector for the charged particle beam. A charged particle beam device characterized in that a small room is formed to secure a space for installation.