JPS6119040A - Manufacture of aperture diaphragm - Google Patents

Abstract

PURPOSE:To manufacture an aperture diaphragm having a rectangular opening with high dimensional accuracy by forming an etching protective mask pattern in an area corrresponding to the opening of the aperture diaphragm and then removing the thin metallic film and the silicon air film. CONSTITUTION:While only one surface of a silicon monocrystal 301 is exposed by using a silicon nitride film 302 as a protective mask, anisotropic etching is performed in a potassium hydroxide solution. Next, after a resist 305 is applied to a thin tungsten film 304, a desired aperture shape is transcribed on the resist 305 by electron beam exposeure to form a resist pattern. Next, thus formed resist pattern is used as a protective mask and the thin tungsten film 304 and a second silicon nitride film 303 are subjected to reactive plasma etching using SFe gas. After that, the resist 305 remaining on the thin tungsten film 304 is removed by O2 plasma, by the means mentioned above, it is possible to manufacture an aperture diaphragm having a rectangular opening with high dimensional accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a number of apertures that define the cross-sectional shape of a charged particle beam in a charged particle beam irradiation device, and a method for manufacturing the same.

(Prior art and its problems) Various charged particle beam irradiation devices are used in the semiconductor device manufacturing process, and the aperture diaphragm plays an important role in forming the cross-sectional shape of the charged particle beam. .

Among these, in electron beam exposure equipment, particularly in so-called variable area exposure type equipment that performs exposure by variable control of a tube with a rectangular cross-sectional shape of the electron beam, the rectangular cross-sectional shape of the electron beam is defined by the opening of an aperture diaphragm for exposure. Therefore, if there is an error in the aperture size of the aperture diaphragm, the rectangular shape of the exposure pattern will be distorted, and the connections between the rectangular patterns will become poor. Figure 1 shows the configuration of a variable area exposure system. Of the two aperture stops 104 and 107 having openings, only the electron beam passing through the opening of the first aperture stop 104 irradiates the electron beam onto the top surface of the first aperture stop 104. , second aperture diaphragm, and illuminates the upper surface of j 107. first and second aperture diaphragm p104,
When the direction of the electron beam is controlled by the shaping deflector 105 placed between the diaphragms 107 and 107, the way the electron beam image projected onto the second aperture diaphragm 107 overlaps with the aperture of the second aperture diaphragm 107 is controlled. By changing the electron beam, an electron beam having a rectangular cross section with a desired area is obtained. Reduce the electronic edge with the lens 1
08 and the projection lens 109, an exposure pattern is formed at an arbitrary position on the material 111 using the positioning deflector 110.

In order to improve the accuracy of the rectangular pattern exposed by the variable area fin light method, and to improve the accuracy of connecting rectangular patterns, it is necessary to improve the processing accuracy of the large number of apertures, for example, the parallelism of the oval-shaped opening. It is necessary to establish a manufacturing method that can form high-precision shapes and orthogonality.

In particular, regarding the orthogonality error of the rectangular opening portion of the aperture diaphragm 9, even if the rectangular cross section of the electron beam is reduced, the orthogonality error will be
Since the original value is maintained as it is, it is one of the factors that must be formed with the highest accuracy among the many apertures.

On the other hand, in the background as described above, the conventional structure with a large number of apertures is shown in FIG.
．． 202t-, the respective blade-like portions were made into a pair so as to face each other, and as shown in FIG. 2(C), two pairs were used and overlapped from above and below to form an opening with a large number of apertures.

However, in a structure like this, errors tend to occur in the parallelism of the rectangular opening depending on how the two opposing blade plates are arranged, and also, depending on how the two pairs of blade plates are stacked, the rectangular opening (Objective of the Invention) The present invention eliminates the drawbacks of the prior art and provides a method for manufacturing a large number of apertures having rectangular openings with high dimensional accuracy. It is about providing.

(Structure of the Invention) According to the present invention, after forming an insulating film on the surface of either one of the semiconductor single crystal substrates, a portion of the insulating film that includes an opening with a large number of apertures and is wider than the opening size is removed. forming a silicon nitride film on the other surface of the substrate and forming a metal thin film thereon; and forming a large number of apertures using the pattern of the insulating film as a protective mask. forming an etching protective mask pattern at a location corresponding to the opening of the aperture diaphragm on the metal thin film, and then removing the metal thin film and the silicon nitride film; A method for manufacturing a large number of apertures is obtained, which is characterized by including the steps of:

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIGS. 3(a) to 3(h) are cross-sectional views showing the main manufacturing steps of the aperture restrictor according to the present invention in the order of the steps.

Figure 3 (,) has the (100) plane as the surface, and 100 to 50
This is a silicon single crystal substrate 301 having a thickness of 0 μm. Both sides of the substrate will be processed in a later process, so both sides should be mirror polished.

In FIG. 3(b), after forming a first silicon nitride film 302 on one surface of a silicon single crystal substrate 301 by CVD' method, a first silicon nitride film 302 is formed on a portion including a large number of apertures. Since the film 302 is removed, the length of one side of the rectangular opening is 11 in order to include a large number of apertures, and the thickness of the silicon single crystal substrate 301 is d, then l+1/ The first silicon nitride film 3 is formed into a rectangular shape with sides equal to or longer than rd.
02 needs to be removed.

FIG. 3(c) shows Si H4, NH,, N! on the other surface of the silicon single crystal substrate 301. A second silicon nitride film 303'i is formed by a plasma CVD method using gas.
It is formed to have a thickness of about 1 μm. The second silicon nitride film 303 needs to have an appropriate tensile stress), and the plasma CVD method has the advantage of being easy to adjust the stress. The tungsten thin film 304 is formed on the nitride film 303 to a desired thickness using the RF sputtering method.The tungsten thin film 304 serves as an electron beam absorption layer, but its thickness is For example, for 20 kV, a thickness of about 12 μm is required. Also, the tungsten thin film 304 is formed under the same conditions as the second silicon nitride film 303 so that it has an appropriate tensile stress. .

In FIG. 3(e), only one surface of a silicon single crystal substrate 301 is exposed and anisotropic etching is performed in a potassium hydroxide solution using the first silicon nitride film 302 as a protective mask. The side of the substrate 301 with the tungsten pattern is protected with a jig so that the etching solution does not come into contact with it. Figure 3 (r) shows the tungsten thin film 304.
A resist 305 tl- is applied thereon, and a desired aperture shape is transferred by electron beam exposure to form a resist pattern.

When a charged particle beam is generally used, such as in a beam exposure, FIG. 3(g) shows a pattern of resist 305 used as a protective mask.
The tungsten thin film 304 and the second silicon nitride film 303i are reactive plasma etched using 8F6 gas.

As shown in FIG. 3 (hl is the resist 305 left on the tungsten thin film 304 removed by 02 plasma), a highly accurate aperture diaphragm can be completely manufactured.

In this example, an EN substrate was used as the semiconductor single crystal substrate, a silicon nitride film was used as the insulating film used as a mask when etching the substrate, and a W film was used as the metal thin film.
An As substrate or the like, a silicon oxide film, or MO# may also be used.

(Effects of the Invention) The large number of apertures for an electron beam exposure apparatus obtained by the present invention has higher dimensional accuracy than the conventional large number of apertures, and more specifically, the degree of orthogonality is higher by one order of magnitude or more. Also, the method of the present invention can be applied only to electron beam exposure.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of an apparatus using variable area exposure method, Figure 2
Figure (aL (bL) (C) is a perspective view showing a conventional structure with multiple apertures, and Figures 3 (, 1 to (h) are cross-sectional views of the main steps of the method for manufacturing multiple apertures for electron beam exposure equipment. In the diagram showing the order of manufacturing steps, 101...electron gun, 102...blanking electrode,
103... Irradiation lens, 104... L-th aperture diaphragm % 105... Shaping deflector, 106... Shaping lens, 107... Second aperture diaphragm fi, 108...
Reduction lens, 109... Projection lens, 110... Positioning deflector, 111... Material, 201... Upper blade-like plate pair, 202... Lower blade-like plate pair, 3o1...・
Silicon single crystal substrate, 302... silicon nitride film, 3
03...Silicon nitride film, 304...Tungsten film, 305...Resist Figure 1 Figure 2 (α) (b) (C) Figure 3 (α) (b) (C1 (ci) ( e)

Claims (1)

[Claims] After forming an insulating film on one surface of the semiconductor single crystal substrate, removing a portion of the insulating film that includes the opening of the aperture diaphragm and is wider than the opening size, and the other surface of the substrate. forming a silicon nitride film thereon and forming a metal thin film thereon; and using the pattern of the insulating film as a protective mask, removing the portion of the substrate including the opening of the aperture diaphragm. , a step of forming an etching protective mask pattern on the metal thin film at a location corresponding to the opening of the aperture stop, and then removing the metal thin film and the silicon nitride film. Production method.