JPS5935501B2 - electron beam equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an electron beam apparatus for observing a sample and exposing an electron-sensitive material using an electron beam.

An electron beam device is a device that uses electron beams to observe samples and expose electron-sensitive materials, but it is not always necessary to irradiate the sample with the electron beam, and the electron beam may sometimes be interrupted. The method is carried out using an electrode placed near the electron beam path and a diaphragm placed in the path. When cutting off the electron beam to the sample, a voltage is applied to the J electrode to change the direction of the electron beam so that it cannot pass through the aperture located below the electrode.

FIG. 1A shows an example of the structure of an electron beam lithography system, which is one of the five types of electron beam systems. In the figure, 1 is a filament, 2 is a magnet, 3 is an anode, 5 is a lens system for reducing the diameter of the electron beam, 6 is an electrode for cutting off the electron beam, and 1 is an electrode for cutting off the electron beam. A diaphragm 8 for cutting is a sample to which an electron beam is irradiated. 4 shows the approximate path of the electron beam.

A method of cutting the electron beam in this structure will be explained with reference to FIG. 1b. (In the figure, the aperture 7 and the structure outside part 2 of the electrode 6 are omitted for explanation.) When no voltage is applied to the thin-cut electrode 6, the electron beam 4 (the spread of the electron beam is omitted in the figure). , only the center line is shown) can pass through the aperture 7. When a suitable voltage is applied to the electrode 6, the electron beam is deflected as shown by 4' and cannot pass through the aperture 7, so that the sample indicated by 8 in FIG. 1a is not irradiated. The disadvantage of this method is that the electron beam 4r narrows the aperture 7 or the electron beam backscattered by the aperture 7 irradiates the inner wall 9 of the passage, and if the device is used for a long time, This is the point where it gets dirty.

These contaminants are usually non-conductive and therefore easily become charged during use of the device, and the position of the regular electron beam 4 fluctuates due to the charged charges.
This becomes a major problem for electron beam lithography systems that aim for accuracy of micrometers or less. The present invention has been made with attention to the above points, and an object of the present invention is to provide an electron beam device configured to prevent the positional fluctuation of an electron beam due to the above-mentioned charging.

Hereinafter, the present invention will be explained in detail with reference to Examples.

FIG. 2 is a sectional view illustrating the structure of the aperture portion in one embodiment of the present invention. As shown in the figure, the electron beam that is cut off and reflected by the diaphragm 11 is transmitted to the diaphragm 10.
and 11, and by irradiating only a small part of the inner wall 9 of the electron beam passage,
The area contaminated by the electron beam can be reduced.

That is, when the voltage of the electrode 6 is 0V, the electron beam 4
The sample 8 is irradiated after passing through 0 and heading in the direction of 12.

When voltage is applied to electrode 6, the direction of the electron beam is bent and
′ direction. This electron beam 1 is cut off by a diaphragm 10. Electron beam 4 backscattered by the aperture 10
is cut off by the diaphragm 11 and trapped between the diaphragms 10 and 11. Therefore, the inner wall 9 of the electron beam passage
The electron beam 12 can be prevented from being contaminated by the electron beam, and even if the electron beam device is used for a long period of time, the position of the regular electron beam 12 will not change due to charging. When considering the structure of the aperture, the direction of the electron beam that hits the aperture and is reflected is important.

The main part of the scattered electron beam is reflected in a direction symmetrical to the direction of incidence and the vertical axis (electron optical axis), similar to when a ball hits a wall. Particularly in an electron beam device such as an electron beam lithography device, very high precision is required, so it is necessary to shield even the scattering of a part of the electron beam that deviates from the main direction. By shielding the electron beam 4' by applying it to the slope of the conical structure shown in FIG. 2 &ζ, the electron beam is effectively scattered toward the inner wall 9 of the electron beam passage. is possible. The electron beam 1 cut off by this is completely confined between the apertures 10 and 11.

Note that the inner wall 9 of the electron beam passage between the apertures 10 and 11 and the parts of the aperture 10 that are irradiated by the electron beam 1 become dirty, but since these are hidden from the original electron beam 4, they are not affected by charging. There is almost no influence. FIG. 3 is a diagram illustrating the size of such a diaphragm structure with reference to the example of FIG. 2.

Let Lb be the distance from the crimp electrode 6 to the aperture 11, L1 be the distance from the crimp electrode 6 to the aperture 10, and La be the distance from the crimp electrode 6 to the surface of the aperture 10 on which the electron beam is reflected.
Let R1 and R be the radius of the apertures 10 and 11, respectively.
Moreover, parameter A is defined as follows.

A=R1/L1 Here, A means the tangent of the blanked electron beam to the electron optical axis.

At this time, the minimum value of the radius R of the aperture 11 can be made small enough to not block the blasted electron beam, so R
>A-Lb condition is determined.

On the other hand, the radius R of the aperture 11 can be increased to the extent that the electron beam reflected by the aperture 10 can be shielded by the aperture 11.

Therefore, the distance from the optical axis of the electron beam when it hits the aperture 11 is such that the travel length projected on the optical axis of the electron beam from blanking until it hits the aperture 11 is the distance from the shriveled electrode 6 to the aperture 10. Since it is the sum (2La-Lb) of the distance La and the distance (La-Lb) from the aperture 10 to the aperture 11, it was multiplied by the tangent and the running length. A・(2La-Lb)
becomes. Therefore, the radius R of the diaphragm 11 and the ζ diaphragm 10 are allowed to reach the above values.

That is, R<A・(2La−Lb) It is.

Therefore, the permissible range of the radius R of the diaphragm 11 is as follows.

That is, the radius R of the aperture 11 is adjusted so as to satisfy the above conditions.
By determining this, it is possible to prevent positional fluctuations of the electron beam due to charging. As an example, L1=100mJ! T
．． If La=11072Lb=98藺 and R1=0.25u, the range of R is 0.24577!1W<R<0.3
It will be 05. FIG. 4 is a graph showing an example of the effect of the present invention. The horizontal axis narrows down the broken electron beam 10
The temperature elapsed time from the start of irradiation to the sample 11 through the rays is shown, and the vertical axis shows the amount of variation in the electron beam position during that time. The solid line a shows the results for the conventional structure, and the dotted line b shows the results for the structure of the present invention shown in FIG.

As can be seen from this, conventionally the position fluctuated by about 0.8 μm over 10 minutes, but by using the aperture according to the present invention, the settling time can be reduced to less than 0.2 μm in about 2 minutes. was completed. Note that the present invention is not limited to the aperture structure, arrangement location, specific numerical values, etc. in the above-described embodiments, but can be appropriately selected and applied depending on setting conditions.

Further, even if the apertures 10 and 11 are made into an integrated structure to facilitate handling, the effects of the present invention do not change. Furthermore, the application of the present invention is not limited to electron beam drawing apparatuses, but can be widely applied to various electron beam application apparatuses that require cutting off of electron beams.

[Brief explanation of drawings]

1A and 1B are diagrams illustrating an example of a conventional electron beam device, FIG. 2 is a diagram illustrating an embodiment of the present invention, and FIG. 3 is a diagram illustrating the size of the aperture structure in the present invention. ,
and FIG. 4 are diagrams showing an example of the effects of the present invention. 1... Filament, 2... Wehnelt, 3... Anode, 4, 4', 4〃, 12.
...Electron beam, 5...Lens system, 6...
・･･･････････････････････････････････････････････････････････････････････････････････････････････････････････････････････････････････････････････････････････････････････････････････』
...Sample, 9...Inner wall of electron beam passage.

Claims (1)

[Claims] 1. A device comprising a means for cutting off an electron beam emitted from a cathode using an electrode and a diaphragm member installed near the path of the electron beam, and using the electron beam to In an electron beam apparatus configured to perform observation of electron beams, exposure of electrophotosensitive materials, etc., the aperture member has a structure including a conical portion having an aperture at the top thereof through which the electron beam can pass; Another member is installed in front of the diaphragm member in the vicinity of the wire path so that the electron beam shredded by the severing means is separated between the diaphragm member and the another member. 1. An electron beam device characterized in that it is configured such that it can be confined between two devices. 2. The diaphragm member and the other member both have a shape with an aperture through which the electron beam irradiated onto the sample can pass, and the diameter R of the aperture of the another member and the aperture of the diaphragm member are the same. The diameter R_1 of the opening and the following relational expression (L_b)/
(L_1)<R/(R_1)<(2L_a-L_b)/
(L_1) (In the above formula, L_a is the distance from the electrode to the surface of the aperture member on which the electron beam is reflected, L_1 is the distance from the electrode to the aperture member, and L_b is the distance from the electrode to the another member. 2. The electron beam apparatus according to claim 1, wherein the electron beam apparatus is configured to satisfy the following.