JPH02222524A - Electron beam exposure process - Google Patents

Abstract

PURPOSE:To enable specific drawing patterns to be accurately formed on a substrate as a work by a method wherein the first exposure evenly exposing the whole drawing pattern and the second exposure duplicatively exposing only the corner parts of the drawing patterns with the said first exposure are performed. CONSTITUTION:Within the electron beam exposure process wherein a glass substrate as a work 10 coated with a resist is irradiated with electron beams to draw specific drawing patterns 20, the first exposure evenly exposing the whole drawing pattern 20 and the second exposure duplicatively exposing only the corner parts 21 of the drawing patterns 20 with the said first exposure are performed. For example, in order to form a square drawing pattern 20, the said second exposure is performed only on the four corner parts 21 of the drawing patterns 20. At this time, the corner parts 21 of the drawing patterns 20 are irradiated with electron beams in the intensity so as to make the corner parts 21 square. The said intensity of the electron beams in the second exposure shall be specified to make the corner parts 21 square by previous simulation etc., in consideration of the sensitivity of the resist.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to the production of photomasks used, for example, in the process of gluing semiconductor devices, and to an electron beam exposure method for directly drawing on silicon wafers.

<Prior Art> A conventional electron beam exposure method will be described with reference to FIGS. 5 and 6. In the following description, a glass substrate serving as an original plate of a photomask will be exemplified as a substrate to be processed.

The electron beam exposure method is an exposure method in which a desired drawing pattern is formed on a glass substrate coated with an EB (electron beam) resist by converging an electron beam with an electromagnetic coil and scanning the substrate with a deflector. means.

When forming a square drawing pattern 20 as shown in FIG. 6(a) on a glass substrate 10 coated with an EB resist, the entire surface of the drawing pattern 20 is uniformly irradiated with an electron beam for exposure. Then, etching is performed to form a drawing pattern 20 on the glass substrate 10.

<Problems to be Solved by the Invention> With the recent development of process technology, the drawing pattern 20 is becoming more and more submicron. In the submicron drawing pattern 20, the corner portions 21 may be rounded instead of the desired drawing pattern 20 having square corners (see FIG. 6(c)). When forming a comparatively finer drawing pattern 20, there is a limit to how thin the electron beam can be, so the drawing pattern 20 tends to be formed approximately round as shown in FIG. 6(C). be.

For example, to improve capacity area efficiency, D
In the trench structure (see FIG. 5) often used for RAM, etc., the capacity is determined by the shape and depth of the trench hole 30, that is, the surface area, so the corner portion 21 is formed round for the reasons mentioned above. If a photomask is used, a trench hole 30 with rounded corners 301 as shown by broken lines in FIG. 5(b) is formed, making it impossible to obtain a predetermined capacity.

In FIG. 5, 31 is the LOGO3 film, 32 is the polysilicon, 33 is the insulating film, 34 is the diffusion layer, and 3 is the LOGO3 film.
5 indicates gate polysilicon.

Also, a drawing pattern 20 formed on the glass substrate 10
In an inspection method that detects a defect in the drawing pattern 20 by directly comparing the data for forming the drawing pattern 20, it is found that the rounded corner 21 is not actually a defect, but is a pseudo-defect. May be detected as a defect. Since such pseudo defects lead to a decrease in productivity, it is necessary to reduce them as much as possible.

As described above, the inability to accurately expose a glass substrate with a desired drawing pattern involves many problems including those mentioned above.

The present invention was devised in view of the above circumstances, and an object of the present invention is to provide an electron beam exposure method that can accurately form a desired drawing pattern on a substrate to be processed.

Means for Solving the Problem> The electron beam exposure method according to claim 1 is an electron beam exposure method that exposes a desired drawing pattern by irradiating an electron beam onto a substrate to be processed whose surface is coated with a resist. hand,
It consists of a first exposure that uniformly exposes the entire drawn pattern, and a second exposure that exposes only the corner portions of the drawn pattern overlapping the first exposure.

The electron beam exposure method according to claim 2 is an electron beam exposure method in which a substrate to be processed whose surface is coated with a resist is irradiated with an electron beam to expose a desired drawing pattern,
It consists of a first exposure that uniformly exposes the entire drawing pattern, and a second exposure that exposes only the outer corners of the drawing pattern.

The electron beam exposure method according to claim 3 is an electron beam exposure method in which a substrate to be processed whose surface is coated with a resist is irradiated with an electron beam to expose a desired drawing pattern,
It consists of a first exposure that exposes only the base pattern in the drawing pattern, and a second exposure that exposes only the edge portion of the base pattern.

<Function> In the electron beam exposure method according to claim 1, double exposure is performed by uniformly exposing the entire drawn pattern in the first exposure and performing the second exposure only on the corner portions so that the corner portions become square. .

Further, in the electron beam exposure method according to the second aspect, the first exposure uniformly exposes the entire drawing pattern, and the second exposure is performed only on the outside of the corner so as to form the corner into a square.

Furthermore, in the electron beam exposure method according to claim 3,
After the first exposure is applied only to the base pattern in the drawn pattern, the second exposure is applied only to the edge portions of the base pattern to form square corner portions of the drawn pattern.

<Example> Hereinafter, an example according to the present invention will be described with reference to the drawings.

FIG. 1 is an explanatory diagram showing an embodiment of the electron beam exposure method according to claim 1, FIG. 2 is an explanatory diagram showing an embodiment of the electron beam exposure method according to claim 2, and FIG. 3 is an explanatory diagram showing an embodiment of the electron beam exposure method according to claim 2. FIG. 4 is an explanatory diagram showing an embodiment of the electron beam exposure method according to the present invention. FIG. 4 is an explanatory diagram of a drawn pattern exposed by the electron beam exposure method according to the present invention. Note that the explanation will be given with the same reference numerals attached to the conventional one and the parts between the paths. Furthermore, in the following description, a glass substrate serving as an original for a photomask will be exemplified as a substrate to be processed. Further, the electron beam exposure method according to the present invention utilizes the low sensitivity of an EB resist for electron beams. That is, it utilizes the property that not all parts irradiated with the electron beam are exposed, but only the parts irradiated with a certain amount of electron beam or more are exposed.

The electron beam exposure method according to claim 1 is an electron beam exposure method in which a glass substrate 10, which is a substrate to be processed and whose surface is coated with a resist, is irradiated with an electron beam to expose a desired drawing pattern 20. The first exposure uniformly exposes the entire surface of the drawing pattern 20, and the corner portion 2 of the drawing pattern 20.
1, and a second exposure in which only 1 is exposed over the first exposure.

When forming a square drawing pattern 20 on the glass substrate 10 whose surface is coated with a resist that responds to electron beam irradiation, the electron beam is irradiated in a shape corresponding to the drawing pattern 20, that is, a square shape. Perform 1 exposure.

This first exposure is performed by uniformly irradiating the entire surface of the desired drawing pattern 20 with an electron beam.

Next, the second exposure is performed only on the four corner portions 21 of the drawing pattern 20 (the portions indicated by diagonal lines in FIG. 1). That is, only the corner portion 21 is subjected to double exposure. Then, since the corner portion 21 is irradiated with more electron beams than other portions of the drawing pattern 20, it is exposed over a wider range than the other portions. Note that the electron beam in the second exposure is irradiated with such intensity that the corner portion 21 of the drawing pattern 20 becomes square.

The intensity of the electron beam in this second exposure is determined in advance by simulation or the like, taking into account the sensitivity of the resist, so that the corner portion 21 becomes square.

When etching is performed after the second exposure is completed, a drawing pattern 20 in which the corner portions 21 are square, that is, a desired drawing pattern 20 can be obtained on the surface of the glass substrate 10.

Further, an electron beam exposure method according to a second aspect is an electron beam exposure method in which a glass substrate 10 whose surface is coated with a resist is irradiated with an electron beam to expose a desired drawing pattern 20. It consists of a first exposure that uniformly exposes the entire area, and a second exposure that exposes only the outside of the corner portion 21 of the drawn pattern 20.

The first exposure is no different from the electron beam exposure method according to the first aspect, but in the second exposure, only the outside of the corner portion 21 is irradiated with the electron beam. Therefore, in the second exposure, only the outside of the corner portion 21 of the drawn pattern 20 is exposed, as indicated by diagonal lines in FIG. In FIG. 2(a), the corner portion 21 is irradiated with an electron beam that irradiates the same area as the drawing pattern 20.
By irradiating only the outside of the drawing pattern 20
The corner portion 21 of is formed into a square shape. Also, the second
In Figure (b), the corner part 21 of the drawing pattern 20 is squared by irradiating only the outside of the corner part 21 with an electron beam that irradiates a narrower area than the electron beam irradiated on the drawing pattern 20 with the first n light. is formed. Furthermore,
In FIG. 2(C), the second exposure is performed to overlap the path light (exposed corner part 21) slightly by the first exposure, and the corner part 21 is formed into a square shape. In this case, as shown in FIG. 4(b), a wider area than the drawing pattern 20 is exposed to the outside of the corner portion 21, but the intensity of the electron beam in the second exposure is By setting the value such that the corner portions 21 are etched squarely, it is possible to obtain a desired drawing pattern 20 in which the corner portions 21 are formed squarely.

Furthermore, the electron beam exposure method according to claim 3 is similar to the above-mentioned two electron beam exposure methods, by irradiating the glass substrate 10 on the surface of which a resist is coated with an electron beam to expose a desired drawing pattern 20. An electron beam exposure method in which a base pattern 22 in a drawing pattern 20 is
It consists of a first exposure in which only the edge portion 221 of the base pattern 22 is exposed, and a second exposure in which only the edge portion 221 of the base pattern 22 is exposed.

The first exposure of this electron beam exposure method differs from the first exposure of the two electron beam exposure methods described above in that the entire drawing pattern 20 is not exposed, but the drawing pattern 20 is
Base pattern 2 set larger or smaller
Expose 2. Since the base pattern 22 includes most of the drawn pattern 20 regardless of its size,
When the base pattern 22 is exposed, most of the drawing pattern 20 is exposed. After the first exposure, a second exposure is performed to expose the edge portion 221 of the base pattern 22. In this second exposure, the drawing pattern 20
The edge portion 221 of the base pattern 22 is exposed to light so as to include the corner portion 21 of the base pattern 22 . It is assumed that the intensity of the electron beam in the second exposure is set to such a value that the corner portion 21 is formed into a square shape by etching, as in the two cases described above.

If the base pattern 22 is larger than the drawn pattern 20, the second exposure is performed only on the portion of the edge portion 221 corresponding to the corner portion 21, as shown by diagonal lines in FIG. 3(a). Pattern 22 is drawing pattern 2
If the value is smaller than 0, the entire edge portion 221 of the base pattern 22 is subjected to the second exposure, as indicated by diagonal lines in FIG. 3(b). By these first and second exposures, at least a portion wider than the portion corresponding to the drawing pattern 20 is exposed, and the corner portion 21 of the drawing pattern 20 is exposed.
Since the portion corresponding to , is irradiated with more electron beams than other portions, the desired drawing pattern 20, that is, the drawing pattern 20 in which the corner portions 21 are square, can be obtained by subsequent etching. .

In the above embodiment, the photomask is manufactured using a glass substrate coated with a resist as an original plate, but the present invention is not limited to the above embodiment, and a silicon wafer is directly irradiated with an electron beam. It can also be applied to so-called direct writing in which a drawing pattern is formed by

<Effects of the Invention> According to the electron beam exposure method according to the present invention, the corner portions of the drawing pattern can be formed square in any case. In other words, the desired drawing pattern can be formed accurately, so there is no difference in capacity due to the rounded corners of the trench hole, and a drawing pattern that actually has no defects is treated as a pseudo defect. Various problems such as being detected do not occur.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an embodiment of the electron beam exposure method according to claim 1, FIG. 2 is an explanatory diagram showing an embodiment of the electron beam exposure method according to claim 2, and FIG. 3 is an explanatory diagram showing an embodiment of the electron beam exposure method according to claim 2. An explanatory diagram showing an example of such an electron beam exposure method, FIG. 4 is an explanatory diagram of a drawing pattern exposed by the electron beam exposure method according to the present invention, and FIG. 5 is a photomask formed by a conventional electron beam exposure method. FIG. 6 is an explanatory diagram showing the problems of the conventional electron beam exposure method. 10...Glass substrate (substrate to be processed), 20...Drawing pattern, 21...Corner part (of the drawing pattern),
22...Base pattern, 221... Edge portion (of the base pattern).

Claims (3)

[Claims] (1) In an electron beam exposure method in which a substrate to be processed with a resist coated on its surface is irradiated with an electron beam to expose a desired drawing pattern, the first exposure uniformly exposes the entire drawing pattern; An electron beam exposure method comprising: a second exposure in which only a corner portion is exposed overlapping the first exposure. (2) In an electron beam exposure method in which a substrate to be processed with a resist coated on its surface is irradiated with an electron beam to expose a desired drawing pattern, the first exposure uniformly exposes the entire drawing pattern; An electron beam exposure method comprising a second exposure of exposing only the outside of a corner. (3) In an electron beam exposure method in which a substrate to be processed whose surface is coated with resist is irradiated with an electron beam to expose a desired drawing pattern, the first exposure exposes only the base pattern in the drawing pattern; an electron beam exposure method comprising: a second exposure for exposing only the edge portion of the electron beam;