JPS5824009B2 - Electron beam exposure equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electron beam exposure apparatus having a mask with holes.

FIG. 1 is a schematic diagram of the simplest exposure apparatus.
The electron beam emitted from is irradiated by the irradiation lens 2 onto a mask 3m having, for example, a rectangular hole 3h.

The electron beam, which has a rectangular cross section and has passed through the hole 3h of the mask, is focused onto the sample 5 by the focusing lens 4, and deflected to an arbitrary position on the sample by the deflector 6, thereby performing exposure.

Now, in such an exposure apparatus, the resolution of the electron beam irradiated onto the sample and the linearity of the cross section of the electron beam are important factors that greatly influence the exposure accuracy.

These depend in part on the thickness of the mask and the straightness of the holes in the mask.

In other words, if the mask 3m is thick as shown in Fig. 2, the electron beam emitted from the upper part P of the hole in the mask will be imaged at point P', and the electron beam emitted from the lower part Q will be imaged at point Q'. Therefore, the resolution of the electron beam on the sample deteriorates, so the mask must be made as thin as possible.

In addition, the linearity of the cross section of the electron beam is a feeding condition for drawing accurate patterns on the sample, and for this purpose the linearity of the hole in the mask must be improved as much as possible.

By the way, the mask just described is realized as described below.

That is, a mask is made by mechanically polishing the cross sections of a plurality of thin plates of high melting point metal and combining the thin plates so that each cross section forms a hole.

However, such mechanical polishing requires a considerable amount of time, and it is difficult to improve linearity.
As a result, it is quite expensive, and furthermore, it is difficult to remove stains by electron beam irradiation.

Another method is to apply a resist on a silicon wafer, irradiate it with light of a certain size, develop it, and then use dry etching or chemical etching to make holes. Etching must be repeated many times, resulting in rounded corners of the holes, the wafer itself becoming brittle, and the cost is quite high.

Recently, a method has been proposed for making a mask using a material that can be easily made extremely thin, for example, a semiconductor single crystal plate such as a silicon single crystal plate.

That is, by folding a silicon single crystal plate of several 100 μm,
A silicon plate having a folded surface with extremely good linearity was obtained, and this was prepared as a surrounding plate, and the concave silicon plate 8a, 8b,
8c and 8d are overlapped.

Since the mask created in this way can be made extremely thin and the holes have extremely high linearity, exposure accuracy is significantly improved.

Also, such a mask can be easily created.

Now, in order for an electron beam exposure apparatus to be used as a practical machine for manufacturing IC elements, LSI elements, VLSI elements, etc. (hereinafter abbreviated as elements), it goes without saying that exposure accuracy must be improved, but in any case, the above-mentioned The goal is to improve device manufacturing speed.

However, if the above-mentioned mask is used, an improvement in the manufacturing speed cannot be expected.

This is because the holes in the mask and the holes become contaminated by electron beam irradiation, and the linearity of the electron beam cross section deteriorates due to uneven charge-up of electrons. This is because each time, the vacuum in the exposure chamber must be broken, the mask must be taken out, and after cleaning, it must be returned to its original position and the exposure chamber must be evacuated to high vacuum again.

A considerable amount of time is spent on breaking the vacuum in the exposure chamber, evacuation to a high vacuum, cleaning the mask, and adjusting the position of the mask.

In particular, high vacuum evacuation and mask position adjustment take a considerable amount of time, so even if you use a new mask without cleaning, the wasted time will hardly be solved, and new cost problems will arise. .

This mask cleaning process (the process of removing the mask from the exposure chamber and attaching it to the exposure chamber) is frequently performed in the actual device manufacturing (mass production), so the time required for the entire device manufacturing is This waste of time may endanger the life of the electron beam exposure apparatus as a practical device manufacturing device.

The present invention has been made in view of these points, and provides a novel electron beam exposure apparatus. Figure 5 of the box is an embodiment of a mask showing the characteristic portions of the present invention.

A mask like this is made as follows.

A semiconductor, such as a single crystal of silicon, is used as the mask material.

First, a silicon single crystal rod having a cross section of (100) or (110) is cut into rings to obtain silicon plates having a thickness of about 100 μm as shown in FIG. 4a.

The cross section of this silicon plate is polished to a thickness of approximately several tens of micrometers.

Since the (100) or (110) crystal plane has the property of being easily interosseous at right angles to this plane, as shown in Figure 4,
Utilizing this characteristic, the silicon plate is folded into a band-shaped piece 9a and semicircular pieces 9b and 9c.

However, the length of the strip-shaped piece 9a in the longitudinal direction is at least twice as long as the length of the hole side of the resulting mask, so that the strip-shaped piece 9a is obtained.

Through such an operation, four strip-shaped inter-fold pieces are obtained, and the inter-fold surfaces of the respective pleat pieces face each other to form a hole 10 to form a strip-shaped inter-fold piece 11a.

11b, 11C, and 11d are combined in a grid pattern as shown in FIG. 5, and this is used as a mask.

This mask is mounted on a mask holder 12a as shown in FIG.

It is supported by 12b, 12c, 12d, 12a', 12b', 12be and 12d' and placed at the position of mask 3m of the electron beam exposure apparatus as shown in FIG.

Note that the holder includes pressing bodies 13a and 13b for longitudinally moving the belt-shaped fold pieces supported respectively.

13c, 13d, 13a', 13b', 13c', and 13d' are provided, and the band-shaped interfold piece can be moved in the longitudinal direction by operating the pressing body from outside the exposure chamber.

Then, the electron beam emitted from the electron gun is irradiated onto the sample through such a mask to draw a desired pattern.

Now, after repeating such exposure many times and reaching the number of exposures required for cleaning, which has been confirmed in advance, the pressing bodies 13a and 13b provided on the mask holder are removed from outside the exposure chamber without breaking the vacuum of the exposure chamber. , 13c.

13d or 13a', 13b', 13c', 13d
' by manipulating either or both of the band-like interfold pieces 11.
a.

Each of the band-like fold pieces is moved in its longitudinal direction so that a hole 10 is formed between the portions 11b, 11c, and 11d that are not hit by the electron beam.

Then start exposing again.

The above process is repeated several times, and only when there is no clean part in the band-like folds, the vacuum in the exposure chamber is broken and the mask is cleaned or replaced with a new mask member.

In addition, it goes without saying that the mechanism for moving the band-shaped interfold piece in the above description is not limited to the above-described pressing body, and that various mechanisms can be considered.

FIG. 6 shows another embodiment of a mask showing the characteristic parts of the present invention.

This is done by preparing two pieces of silicone band-shaped inter-fold pieces as described above, and as shown in FIG. The orthogonal strip-shaped inter-fold pieces are made perpendicular to each other at each end, and the conductor or semiconductor 15a, 16b is orthogonal to each other as shown in the figure, so that a hole 15 is formed by the perpendicular inter-fold planes. Combine with.

It is fixed to the conductor or semiconductor and is perpendicular to the conductor or semiconductor, and supported by mask holders 17a, 17b, 17a', 17b'.

On the other hand, the band-like fold pieces 14a, 14b are supported by mask holders 18a, 18b, 18a, '18b', respectively, and the pressing body 1 provided on the holders 18a, 18b is
9a and 19b are orthogonally arranged so as to be movable in the longitudinal direction.

For such a mask, a focusing lens 22 and a deflector 23 are arranged between two upper and lower masks 20m and 21m having rectangular holes 20h and 21h, respectively, as shown in FIG. The electron beam EB1 from the electron gun (not shown) that has passed through the hole 20h is directed to the focusing lens 2.
2 to focus on the lower mask 21m (at this time,
The electron beam having a rectangular cross section that has passed through the hole 20h passes through the lens 22.
is inverted and imaged onto the mask 21m.

) At the same time, the electron beam EB2 is arbitrarily deflected by the deflector 23 to obtain an electron beam EB2 having an arbitrary cross section from the hole 21h of the mask 21m, and is irradiated onto a sample (not shown) to draw a pattern. It is used for the upper and lower masks 20m and 21m of the electron beam exposure apparatus to be used.

Therefore, the areas where contamination by electron beams is a problem in the respective holes of the upper and lower masks are two sides 24X of the four sides of the upper mask.

24y, and in the lower mask, there are only two sides 25x and 25y, so when the number of exposures required for cleaning is reached, press body 19
It is only necessary to move only the band-like interfold pieces 14a and 14b in the longitudinal direction by a and 19b, respectively.

Of course, at this time, the electron beam EB2, which has a rectangular cross section and passes through the hole 21h of the lower mask 21m, passes along the side 24X of the hole formed by the interfold surface of the strip-like pleated piece.

Since it is formed by 24y, 25x, and 25y, its linearity and resolution are extremely good.

That is, by using a mask, which is a characteristic part of the present invention, as shown in FIG. 6 in such an exposure apparatus, further effects can be obtained.

In addition, in the example, a semiconductor single crystal interfold piece is used as an example of the material of the mask, but the invention is not limited to this.
Any belt-shaped object with low electrical resistance that can be made thin and has a surface with good linearity can be used.

According to the present invention, in electron beam exposure, whenever mask contamination due to electron beam irradiation progresses, the vacuum in the exposure chamber is broken, the mask is cleaned or a new one is prepared, and the mask is returned to its original position for exposure. Simply move some or all of the strips that make up the mask and replace the mask with uncontaminated parts of the strip, without going through the time-consuming process of pumping the room to a high vacuum. Since the holes are formed, the time required for the entire device fabrication is greatly shortened, and an electron beam exposure apparatus using such a mask is suitable as a practical device for fabricating devices.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of an electron beam exposure device using a mask, Figure 2
The figure is a partially enlarged view, FIG. 3 is a conventional mask making diagram, FIG. 4 is an example diagram showing the mask making process of the present invention, FIG. 5 is an example diagram of an embodiment of the mask of the present invention, and FIG. The figure is a diagram of another embodiment of the mask of the present invention, and FIG. 7 is a schematic diagram of an electron beam exposure apparatus having two masks in which the cross-sectional shape and size of the electron beam from an electron gun can be varied. . 1... Electron gun, 5... Sample, 9a...
...Strip-like piece of silicon plate, 10 ...holes,
11a, 11b. 11c, 11d... Band-like interfold pieces, 12a, 12
b12c, 12d, 12a', 12b',
12c', 12d'...Mask holder, 13
a, 13b, 13c. 13d, 13a', 13b', 13c', 1
3d'..." Pressing body, 14a, 14b... Band-shaped fold piece, 15... Hole, 18 a, 18b
, 18a', 18b'-...mask holder, 1
9a, 19b... Pressing body.

Claims (1)

[Claims] 1. A device that irradiates an electron beam emitted from an electron beam generator onto a mask with polygonal holes and focuses the electron beam that has passed through a reading tag at an arbitrary position on a sample. An electron beam exposure apparatus characterized in that the mask is formed by crossing a plurality of band-like objects, and all or part of the band-like objects are movable in the longitudinal direction. 2. An electron beam exposure apparatus according to claim 1, wherein the mask is formed of a plurality of semiconductor single crystal interfold pieces such that the interfold surface of each interfold piece forms an edge of a hole. 3. A patent claim in which a plurality of masks are provided at intervals in the optical axis direction, so that only the strip-shaped objects forming the mask can be moved in the longitudinal direction, where contamination due to inner basket ray irradiation is a problem. Electron beam exposure equipment according to range 1 of