JP3079547B2 - Charged particle beam equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charged particle beam apparatus having a conical or frustoconical objective lens in order to secure a space for tilting a sample in a sample chamber.

[Conventional technology]

This type of charged particle beam apparatus has a conical or frustoconical objective lens, so that a wide space can be obtained around the objective lens, so that the sample can be tilted in the sample chamber. If the inclination angle of the sample can be made large, the angle of the cone becomes small, and the space around the objective lens becomes large.

[Problems to be solved by the invention]

In the prior art as described above, there is a problem that the structure of the pump connected to the lens barrel becomes complicated because the degree of vacuum inside the lens barrel connected to the sample chamber cannot be maintained satisfactorily. Therefore, an object of the present invention is to provide a charged particle beam apparatus in which the degree of vacuum inside the lens barrel is easily increased with a simple pump configuration.

[Means for solving the problem]

In order to solve the above problems, the present invention according to claim (1) provides a conical or frustoconical objective lens (1, 1) in order to secure a space for tilting a sample (9) in a sample chamber (5). 2,
In the charged particle beam device having the above (3), an exhaust device (4) for exhausting a space until the charged particle beam emitted from the openings (1, 2, 3) of the objective lens comes into contact with the sample (9).
Is a charged particle beam device provided around the objective lens (1, 2, 3) and avoiding a space for tilting the sample (9). According to the present invention, in order to secure a space for tilting the sample (9) in the sample chamber (5), a conical or frustoconical objective lens (1,
In the charged particle beam apparatus having the above (2) and (3), gas introducing devices (5a, 5b) for introducing a low-pressure gas into the sample chamber (5).
And an exhaust device (4) for exhausting a space until the charged particle beam emitted from the opening of the objective lens (1, 2, 3) comes into contact with the sample (9). The charged particle beam apparatus is provided outside of (3) and avoiding a space for tilting the sample (9). The present invention described in claim (3) is characterized by claim (1).
Alternatively, in the charged particle beam device according to (2), the exhaust device is configured to secure a traveling space for the charged particle beam from the sample and to secure a space for disposing a detector for the charged particle beam. A charged particle beam apparatus characterized by forming a small chamber.

[Action]

In the inventions described in claims (1) and (2), an exhaust device is provided in a space around the objective lens to exhaust the space until the charged particle beam emitted from the opening of the objective lens comes into contact with the sample. Therefore, it is possible to 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 vacuum inside the lens barrel. Further, since the exhaust device of the present invention is disposed in the space around the objective lens which has not been used conventionally, the charged particle beam device does not have to be particularly large.

Furthermore, in the invention described in claim (3), a small room for securing a traveling space for charged particle beams from the sample and a space for disposing a detector for the charged particle beams in the exhaust device. Since the unit is provided, it is possible to detect the charged particle beam from the sample without any trouble even though the exhaust device is provided.

〔Example〕

FIGS. 1 (a) and 1 (b) show an ESEM as an embodiment of the charged particle beam apparatus of the present invention.
Microscopy (a microscope that uses the electron amplification effect of introducing low-pressure gas such as water vapor and nitrogen into the sample chamber and reflecting electrons from the sample and secondary electrons ionizing these gases) FIG. FIG. 1A is a transverse sectional view (a sectional view taken along the line AA 'in FIG. 1B), and FIG. 1B is a sectional view taken along the line BB' in FIG. 1A. It is sectional drawing.

1 (a) and 1 (b), the objective lens comprises an upper pole 1, a lower pole 2, and a coil 3, and is designed to have a truncated cone shape so that the sample can be tilted up to about 60 °. An exhaust pipe 4 for exhaust is provided outside the lower pole 2 of the objective lens. As shown in FIGS. 1 (a) and 1 (b), the exhaust tube 4 has a space for tilting the sample, a space for a detector 8 to which a positive voltage is applied, and a secondary electron detector. In order to secure a space for traveling to the vehicle, the first small room portion 4a (corresponding to the former) and the second small room portion 4b (the latter) in a direction (Y direction) orthogonal to the exhaust direction (X direction). Corresponding).
The exhaust pipe 4 for this exhaust has holes 6 through which electron beams pass.
(The sample side) and the hole 7 (the objective lens side). These holes 6 and 7 are used to obtain a low-magnification SEM image.
Has a size of 1 mmφ, and the hole 6 has a size of 2 mmφ. The exhaust conductance of the exhaust pipe 4 is substantially determined in the narrowest space 10,
A rotary pump (not shown) is connected to the end of the discharge pipe 4 to sufficiently achieve the purpose. The sample chamber 5 is evacuated through tubes 5a and 5b, and a low-pressure gas such as water vapor or nitrogen is introduced. The sample 9 is introduced into the electron beam irradiation position of the sample chamber 5 by a transfer device (not shown). The transfer device is a known device including a transfer arm or the like (not shown) and a moving stage.

Here, the operation of the exhaust pipe 4 is as follows. That is, the pressure P _{10 in} the space between the holes 6 and 7 where the exhaust conductance of the small holes 6 and 7 and the exhaust port 10 in FIG. 1 is G ₆ , G ₇ and G ₁₀ and the sample chamber pressure is P ₉ , respectively. Becomes The exhaust conductance is approximately proportional to the opening area, if _{G 6 = K · π · 1} 2, G 10 = K · 2 × 5 × π × 4 ( where K is determined constants type of gas, etc.), Becomes

That is, the pressure between the holes 6 and 7 is 1/40 of the sample chamber pressure.

Therefore, the inside vacuum of the lens barrel can be increased to 1/40 as compared with the conventional ESEM. Alternatively, it can operate at a pressure 40 times higher in the same lens barrel vacuum. Or, from another perspective, the capacity of the exhaust pump that exhausts the lens barrel can be reduced to 1/40.

With such a configuration, the electron beam that has exited the holes at the lower ends of the objective lenses 1, 2, and 3 reaches the sample 9 through the holes 7 and 6 of the exhaust tube 4. Reflected electrons and secondary electrons are generated from the sample 9, and these electrons travel toward the detector 8 while ionizing gas molecules in the sample chamber 5. As a result, in addition to reflected electrons and secondary electrons from the sample 9, electrons generated by ionization in 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 (see US Pat. No. 4,781,182).

At this time, the inside of the lens barrel must be maintained at a high vacuum. However, since the space until the electron beam emitted from the openings of the objective lenses 1, 2, and 3 comes into contact with the sample is exhausted by the exhaust pipe 4, Even though gas is introduced into the sample chamber 5, it is possible to effectively reduce the degree of vacuum inside the lens barrel.

When the sample 9 is to be tilted, the sample 9 may be tilted by using a space in the sample chamber 5 formed outside the first small chamber portion 4a of the exhaust pipe 4. Only one direction of the inclination of the sample 9 is sufficient.

〔The invention's effect〕

According to the present invention, the degree of vacuum inside the lens barrel can be improved by providing the exhaust device in a space outside the conical or frustoconical objective lens, which has not been conventionally used. Alternatively, if the degree of vacuum is the same, the apparatus operates even if the degree of vacuum in the sample chamber is increased. From another viewpoint, the pump capable of exhausting the lens barrel may have a low capacity.

The present invention can be applied to an apparatus for processing a sample by introducing a reactive gas into a sample chamber and performing a selective deposition in addition to the ESEM.

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

[Brief description of the drawings]

1 (a) and 1 (b) are views showing an embodiment of the present invention, and FIG. 1 (a) is a cross-sectional view of the embodiment (a cross section taken along line AA 'in FIG. 1 (b)). FIG. 1B is a cross-sectional view taken along the line BB ′ of FIG. 1A. [Description of Signs of Main Parts] 4... Exhaust tube, 4a, 4b.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-1-309243 (JP, A) JP-A-56-38756 (JP, A) JP-A-59-143249 (JP, A) JP-A-2- 210748 (JP, A) Japanese Utility Model Sho 61-77543 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01J 37/141 H01J 37/18 H01J 37/20

Claims (2)

(57) [Claims] An object lens and a charged particle beam detector,
In a charged particle beam apparatus for observing a sample surface by introducing a low-pressure reactive gas into a sample chamber and utilizing an electron amplifying action by reflected electrons or secondary electrons from the sample ionizing these gases, A charged particle beam apparatus characterized by performing selective deposition on a sample surface. 2. A pressure-reducing aperture, an objective lens, and a charged particle beam detector provided outside the lens at a position farther than a distance from a sample surface to the pressure-restriction aperture. A gas is introduced, and the reflected electrons or secondary electrons from the sample utilize the electron amplification effect of ionizing these gases to observe and process the sample surface, or place a selective depot on the sample surface. A charged particle beam apparatus characterized by performing.