JP2002365787A - Projection mask, electron beam exposure method, electron beam aligner, semiconductor device and production method for semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the dimensional accuracy of a pattern formed on a board by suppressing the reflection of a dimensional error on the board being an object to be exposed during the production of a projection mask. SOLUTION: This projection mask 3 for transmitting a electron ray and selectively exposing the board 1 is provided with a plurality of exposure regions 4a, 4b, 4c, 4d, etc., where the predetermined pattern for exposing the board 1 formed, and marks 6 for dimensional measurement formed in correspondence with the exposure regions 4a, 4b, 4c, 4d, etc. The pattern with a uniform line width can be exposed by correcting an electronic radiation dosage of the basis of the measured result of the line width of the mark 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection mask, an electron beam exposure method, an electron beam exposure apparatus, a semiconductor device, and a method for manufacturing a semiconductor device. The present invention is suitable for use in a projection mask to be used, an electron beam exposure method using the projection mask, an electron beam exposure apparatus, a semiconductor device manufactured using the projection mask, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, in the manufacture of semiconductor integrated circuits, a transfer technique using light using a mask has been mainly used. This is because transfer using a mask has a very high throughput and is rich in mass productivity.

[0003] On the other hand, the electron beam direct writing technology is used for advanced trial production of advanced devices and for manufacturing semiconductor integrated circuits for small-scale production due to its high resolution, but its throughput is slower than that of light exposure. At present, it has not been put to practical use in the manufacturing process of mass-produced semiconductor integrated circuits.

An exposure method called a partial batch method has been proposed to overcome the drawback of a delay in throughput in the electron beam direct writing technique. This method is based on the character projection method,
Although various names such as a cell projection method and a block exposure method are given, the essential methods are the same. To improve the throughput of electron beam direct writing method,
It is important to reduce the actual number of shots. For this reason, in the partial batch method, a mask in which a pattern that repeatedly appears is stored in a predetermined area range is created, and the pattern section that repeatedly appears is exposed using a mask in this range. . Patterns that appear less frequently are exposed with a variable shaped beam using a pattern creation function, which is also a special feature of the direct electron beam drawing method, without creating a mask in advance. According to such a partial batch method, the number of shots can be reduced as compared with the case where all patterns are exposed by the pattern creation function, and this can contribute to an improvement in throughput.

[0005] However, even if the partial batch method is used, the processing speed that can be realized is at most several per hour for an 8-inch wafer, and it is not practically practical from the viewpoint of productivity. Was enough.
Therefore, in electron beam lithography, there is a growing tendency to introduce a mask having an image completely the same as that of a chip in the same manner as in optical lithography. The electron beam projection lithography technique is a technique developed from such a viewpoint, and is intended to realize a processing speed comparable to that of photolithography by collectively transferring a mask image. This technology is being embodied as a technology called SCALPEL by a group of AT & T Bell Laboratories (now Lucent Technologies) and as a PREVAIL technology by a joint research and development organization of Nikon and IBM.

Here, in a technique called SCALPEL, a mask pattern made of a heavy metal material obtained by enlarging a semiconductor integrated circuit pattern several times is arranged on a continuous supporting film to form a scatterer, and a projection mask is formed by using this as a pattern source. are doing. In the technology called PREVAIL,
A hole is formed through the film itself of the projection mask, and a mask pattern obtained by enlarging the circuit pattern by several times is used as a scatterer depending on the presence or absence of the hole, and a mask (stencil mask) is configured using this as a pattern source. In these methods, although there is a difference in the structure of the scatterer of the mask, pattern formation is performed at high speed by reducing and projecting the semiconductor integrated circuit pattern using such a mask.

The projection mask used here has a structure in which a beam is inserted to support the film due to structural restrictions (mechanical strength), and a silicon wafer is usually used as a substrate of the projection mask. In the electron beam projection lithography technique, a semiconductor integrated circuit pattern is divided into a large number of fields, and exposure is performed by changing a mask pattern on a projection mask for each field. In this exposure, connection for each field is difficult. Accordingly, there is a problem that a difference in Coulomb effect due to a difference in pattern density causes a connection deviation, and a change (enlargement and reduction) in a pattern dimension for each subfield due to an improper exposure amount.

In order to prevent such a problem, when exposing each subfield, a table for correcting rotation components, magnification components, and the like for preventing connection deviation, and a dimensional variation due to the magnitude of the pattern density. A table for adjusting the amount of exposure to prevent the exposure is required.
These tables usually use marks pre-formed at the time of mask production, and before exposure, before exposure, an exposure device or a measurement device (for overlay, for example, an interference type coordinate measuring machine) or data conversion software (sub-field) Aperture ratio: corresponding to the pattern density), and is referred to by exposure control software of an exposure machine at the time of exposure. This is designed so that a uniform chip pattern with no connection deviation can be exposed.

[0009]

However, in the above-described method, it is possible to reduce the connection deviation for each field and the dimensional fluctuation that occurs when an appropriate exposure amount is not given. The generated error could not be suppressed. The error factors described above are based on the premise that the pattern of the projection mask is formed as designed, and the conventional method only reduces the error that occurs in the process when an appropriate projection mask is used. Did not.

On the other hand, it is very difficult to prevent the dimensional error of the mask pattern itself which occurs in the process of manufacturing the projection mask, and it is necessary to suppress the deterioration of the pattern accuracy caused by the dimensional error of the projection mask itself. Could not. For this reason, there has been a problem that a dimensional error of the projection mask itself is directly reflected on a substrate such as a silicon wafer to be exposed.

The mask exposure for manufacturing a projection mask is realized by a resist process of electron beam exposure. For example, on an 8-inch wafer used for the mask, the in-plane dimensional distribution of the etching rate of the mask pattern is uniform. Not necessarily, and a distribution always occurs in the etching rate. This distribution is often distributed concentrically within the wafer surface, but the distribution of the etching rate causes variations in mask pattern dimensions over the entire surface of the projection mask. In the conventional method, a dimensional error of a mask pattern caused by such a dimensional variation of a projection mask is directly reflected on a substrate to be exposed, so that dimensional accuracy of a pattern formed on the substrate is deteriorated. Had become.

SUMMARY OF THE INVENTION It is an object of the present invention to improve the dimensional accuracy of a pattern formed on a substrate by preventing a dimensional error in manufacturing a projection mask from being reflected on a substrate to be exposed. .

[0013]

A projection mask according to the present invention is a projection mask for selectively exposing a substrate by transmitting an electron beam, wherein a predetermined pattern for exposing the substrate is formed. A plurality of exposure regions, and a pattern for dimension measurement formed in proximity to each of the plurality of exposure regions.

A thin film on which the plurality of exposure regions are formed; and a beam formed at a boundary portion between the adjacent exposure regions, wherein the pattern for dimension measurement is provided within the region of the thin film. Is formed outside the.

[0015] Further, there is provided a thin film on which the plurality of exposure regions are formed, and a beam formed at a boundary portion between the adjacent exposure regions, wherein the pattern for dimension measurement is formed at the position of the beam. Things.

Further, the pattern for dimension measurement is formed in a convex shape or a concave shape.

Further, the pattern for dimension measurement is constituted by holes penetrating the thin film.

Further, the dimension measurement pattern is a linear pattern, a block pattern, or a pattern in which a plurality of these patterns are arranged.

Further, the dimension measurement pattern corresponding to one exposure area is constituted by at least two or more patterns having different line widths.

An electron beam exposure method according to the present invention is a method for selectively exposing a substrate using a projection mask having a plurality of exposure regions, wherein a representative pattern corresponding to a pattern formed in the exposure region is provided. The method includes a first step of detecting a dimension for each of the exposure areas, and a second step of correcting an electron dose applied to each of the exposure areas based on the detected representative dimension.

Further, in the first step, the representative dimension is detected by using a dimension measuring pattern formed corresponding to each of the plurality of exposure regions.

In the first step, the representative dimension corresponding to each of the plurality of exposure regions is detected at once, and the corrected electron beam of the electron dose is sequentially applied to each of the plurality of exposure regions. Irradiation.

Further, each time the representative dimension corresponding to one exposure area is detected in the first step,
The correction in the second step is performed, and the exposure area is irradiated with an electron beam.

An electron beam exposure apparatus according to the present invention irradiates an electron beam onto a substrate using the above-mentioned projection mask.

A semiconductor device according to the present invention is manufactured using the above-described projection mask.

A method of manufacturing a semiconductor device according to the present invention is to manufacture a semiconductor device by using the above-described electron beam exposure method.

[0027]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows that an electron beam is applied to a substrate 1 such as a silicon wafer by an electron beam projection lithography technique using an electron beam projection exposure apparatus provided with a reticle (projection mask) 3 according to an embodiment of the present invention. It is a schematic perspective view which shows a state.

As shown in FIG. 1, the electron beam emitted from the electron gun passes through the first shaping aperture 2 and is irradiated on the reticle 3. On the reticle 3, sub-fields (exposure areas) 4a, 4b, 4
., 4d,... are formed separately. Substrate 1
The one-chip pattern above shows these subfields 4
A pattern is formed by irradiating a predetermined position on the substrate 1 with an electron beam transmitted through a, 4b, 4c, 4d,... sequentially as a subfield image.

FIG. 2 is a sectional view showing in detail the periphery of the subfield 4b shown in FIG. 1, and is a view corresponding to the section taken along the one-dot chain line II 'shown in FIG. Here, FIG. 2 shows the state of the reticle 3 shown in FIG. 1 upside down. As shown in FIG. 2, the reticle 3 is a thin film 3 integrally formed from a substrate made of silicon.
a and a beam 3b (not shown in FIG. 1) projecting from the thin film 3a. The beam 3b is formed in a lattice pattern between the subfields 4a, 4b, 4c, 4d,.

Each subfield 4a, 4b, 4c, 4d
, And between the beams 3b, the subfields 4a, 4b,
Non-exposure area (skirt) 5 adjacent to 4c, 4d,.
Are formed. The non-exposure region 5 is formed so as to surround each of the subfields 4a, 4b, 4c, 4d,... Along the lattice beam 3b.

Each subfield 4a, 4b, 4c, 4d
.. Have a predetermined circuit pattern formed on the substrate 1 for forming a semiconductor integrated circuit. When the reticle 3 is formed of a stencil mask, a circuit pattern is formed in the thin films 3a of the subfields 4a, 4b, 4c, 4d,. Also, SCALP
In the case of an EL projection mask, a circuit pattern made of a heavy metal film or the like is formed on the surface of the thin film 3a.

FIG. 3 is a schematic perspective view showing a state in which the reticle 3 is overlooked from above in FIG. As described above, each of the non-exposure areas 5 is composed of each of the subfields 4a, 4b, 4c, 4d.
... are formed. .. Between the subfields 4a, 4b, 4c, 4d,.
An unexposed region (hereinafter, referred to as a back side portion of the beam 3b) is formed corresponding to the upward extension of the shape of (3).

Each subfield 4a, 4b, 4c, 4d
.. Are formed in a 1000 μm × 1000 μm square area, and a predetermined circuit pattern is formed in this area. Here, since the reticle 3 is a four-fold reticle, the subfield image corresponding to each of the subfields 4a, 4b, 4c, 4d, etc. irradiated onto the substrate 1 has an area of 250 μm × 250 μm. Become. That is, the pattern of the reticle 3 is 1 /
The projection is reduced to four times.

In this embodiment, as shown in FIGS. 1 and 2, each of the subfields 4a, 4b, 4c,
A dimension control mark 6 is provided in the non-exposure area 5 close to 4d... Or the back side of the beam 3b. In FIG.
Although the mark 6 has a convex shape, the mark 6 may be concave as described later, or the mark 6 may be formed as a hole penetrating the thin film 3a. In particular, when the reticle 3 is a stencil mask, the thin film 3a in the non-exposed region 5
It is preferable to form the mark 6 by a hole penetrating through.

The dimensional accuracy, in particular, the subfields 4a, 4
b, 4c, 4d... In order to improve the variation in the size of the subfield image caused by the difference in the pattern size between them, it is desirable to minimize the difference in the finished size of the reticle 3, which is the original plate. It is impossible to make this dimensional difference zero. Therefore, in this embodiment, each subfield 4a, 4b, 4c, 4d,.
, A mark 6 as a pattern indicating a typical resolution is provided.

The position where the mark 6 is to be inserted is desirably formed on the thin film 3a of the reticle 3 which does not cover each of the subfields 4a, 4b, 4c, 4d. That is,
The mark 6 is formed of each subfield 4a, 4b, 4c, 4d of the membrane having the same thickness as the pattern to be actually exposed.
... It is preferable to arrange in the non-exposure area 5 at the end (arrangement at the mark position (1) shown in FIGS. 2 and 3). on the other hand,
When there is a restriction on the arrangement of the mark 6 in the non-exposure area 5, or when the arrangement itself is prohibited, the beam 3b
(Arrangement at the mark position (2) shown in FIGS. 2 and 3). Mark 6 on the back side of beam 3b
In this case, since the thickness of the beam 3b is larger than the thickness of the thin film 3a, it is necessary to consider the influence of backscattering and the influence of an environment difference from the actual pattern area at the time of etching.

When the marks 6 inserted in this manner are inserted one by one into each of the subfields 4a, 4b, 4c, 4d,..., For example, 1600 locations for a 4-inch reticle, In the case of an 8-inch reticle, it will be placed at 8000 places.

It is desirable that these marks 6 are relatively close to the pattern size of the device drawn by the reticle 3 and are simplified patterns. For example, when the pattern of the reticle 3 corresponds to a line-type pattern, the reticle 3 is of a slit type assuming that a process is finally performed using a negative resist in electron beam projection lithography. In this case,
It is desirable that the mark 6 be a combination of a group of lines and spaces, a combination of isolated lines (slits), and the like. If the reticle 3 corresponds to a hole-based pattern, the reticle will be a hole type assuming that a process is finally performed with a positive resist in electron beam projection lithography. In this case, a combination of holes by groups, a combination of isolated holes, and the like is desirable.

It is more desirable that these marks 6 are inserted not only with one line width but also with two or more line widths as typical line widths. By inserting two or more line widths, preferably a large line width and a small line width, it becomes possible to further remove the correction residual component of the proximity effect correction in the electron beam drawing at the time of manufacturing the reticle. That is, 1
In the case where the mark 6 is configured with the line width of the type, the design value (the reticle size × (1 in the case of the 4 × mask) and the reticle size × (1 / 4) Exposure is performed so as to be close to ()). In this case, if the finished dimension of the reticle pattern having a line width much smaller than that of the mark 6 having one kind of line width is a slit smaller than the line width of the mark 6, the 1
Since the exposure is performed based on the line width of the type, a much thinner pattern is finished finer. If there are two types of line width information, by increasing the exposure amount by a certain ratio based on the information of the small line width, although a certain dimension becomes thicker,
The size of the minute width can be made closer to the target size.

The inserted mark 6 needs to have a line width that can be measured by a line width measuring device or a line width measuring function incorporated in an exposure device. Generally, electron beam projection lithography uses a reticle 3 having a pattern four times as large as the actual circuit pattern on the substrate 1, so that measurement using these measuring devices or measuring functions is relatively easy.

FIGS. 4A to 4D are plan views showing examples of typical mark 6 pattern shapes used in this embodiment. Here, FIG. 4A shows an example in which the mark 6 is formed by dense dots or holes, and FIG. 4B shows an example in which the mark 6 is formed by isolated dots or holes. I have. Here, the dot means the mark 6 as shown in FIGS.
Refers to a pattern formed so as to protrude from the surroundings.
The hole refers to a pattern formed so that the mark 6 is more concave than the periphery, and particularly includes a case where a through hole is formed in the non-exposed area 5 of the thin film 3a.

FIG. 4C shows an example in which the mark 6 is formed by dense lines or grooves, and FIG. 4D shows an example in which the mark 6 is formed by isolated lines or grooves. Here, the line refers to a pattern formed so that the mark protrudes from the periphery. The groove refers to a pattern formed so that the mark 6 is more concave than the surroundings, and particularly includes a case where a through hole is formed in the non-exposed area 5 of the thin film 3a. The space refers to a region between lines or between grooves.

When these marks 6 are measured by the line width measuring apparatus or the line width measuring function incorporated in the exposure apparatus, the respective edges of lines, grooves, spaces, holes, and dots are detected. It can be carried out.

The mark 6 may be a pattern other than the shape shown in FIG. For the X direction and Y
The directions may be inserted separately along the edges of different subfields.

The mark 6 inserted here corresponds to the reticle 3
Through a resist process (developing etc.) for forming the reticle 3, an etching process for forming the reticle 3, a cleaning process, etc.
.. are formed through the same history as the circuit patterns a, 4b, 4c, 4d,. Therefore, in a process in which the size varies between subfields, the mark 6 is finished in a manner that reflects the variation and indirectly reflects the line width of the final circuit pattern. This is because each mark 6 has a subfield 4a, 4
This is because they are arranged as close as possible to b, 4c, 4d,.

Since the finished mark 6 reflects the line width variation in the reticle 3 of each of the subfields 4a, 4b, 4c, 4d,... The line width of the mark 6 is measured as a representative dimension of each of the subfields 4a, 4b, 4c, 4d,. It is possible. When the electron beam projection exposure apparatus itself has such a line width measurement function of the mark 6, it is also possible to sequentially acquire these data just before the actual exposure.

If the line width of the mark 6 is measured by a line width measuring machine before exposure, for example, the line width slit is narrower than this average value based on the average value of the obtained data. When exposing the sub-field corresponding to the mark 6 having the mark 6, the exposure amount is increased in accordance with the degree of finishing, and the mark 6 having a line width thicker than the average value is finished.
In the case of exposing a subfield corresponding to (1), an operation of reducing the exposure amount according to the degree of finishing is performed. This makes it possible to perform ideal exposure independent of the line width distribution in the reticle plane. The measurement may be performed before mounting the reticle 3 on the electron beam projection exposure apparatus, or may be performed by mounting a line width measuring machine below the reticle 3 after mounting the reticle 3 on the electron beam exposure apparatus. good. As shown in FIGS. 1 and 2, when the reticle 3 is mounted on the electron beam projection exposure apparatus, the mark 6 is located on the lower surface side of the reticle 3, so that the measurement can be performed from below by the line width measuring device. . As described above, when the line width is measured in advance, after correcting the electron dose based on the table in which the line width data of all the marks 6 are recorded, the corrected amount of the electron beam is sequentially transmitted to each of the marks. Irradiate the sub-fields 4a, 4b, 4c, 4d,.

More specifically, in a subfield in which the reticle line width (for example, a film removal pattern) is finished smaller than the average value, a larger amount of electron beam irradiation than the average value is applied to increase the size shift. (In the case of a negative resist). On the other hand, in a subfield in which the reticle line width is larger than the average value, the electron beam irradiation amount is set to be smaller than the average, so as to promote a narrower size shift. For example, when the exposure with the electron beam is performed on both the subfield patterned with a thickness of −10 nm thinner than the designed value and the subfield patterned with a thickness of +10 nm as it is, when the MEF is 1, Although a dimensional error of ± 10 nm occurs on the substrate 1, this method can approach the design value in either case.

Such a mark 6 is formed on the electron beam projection exposure apparatus.
In the case where the line width measuring function is provided, a certain target standard is set, and the exposure amount can be increased or decreased by the difference between the target standard and the measured mark size. In such an exposure apparatus, after measuring the line width of the mark 6 corresponding to one subfield, the electron dose applied to the subfield is corrected based on comparison with a target reference, and based on the corrected value. By irradiating an electron beam, each subfield 4a, 4
.., 4c, 4d,... can be corrected in real time. Then, the same effect as in the case where the line width of the mark 6 is collectively measured by the line width measuring device in advance can be obtained. In this case, since the exposure amount to be corrected depends on the type and process of the resist used for the actual exposure, it is necessary to collect basic data relating to the line width linearity in advance and reflect it in the actual exposure. Needless to say.

The bias amount of the exposure amount corresponding to the dimensional error of the reticle line width varies depending on the type and process of the electron beam resist used and the pattern shape. Basic data relating to the relationship between the exposure amount and the dimension (which is approximately linear) and the linearity of the line width in the line width used for the mark 6 of a space, an isolated line, an isolated space, a dot, a dot array, a hole, a hole array, etc. Must be obtained, and this must be fed back to the electron beam projection exposure apparatus.

As described above, according to this embodiment, each subfield 4a, 4b, 4c, 4d,.
By correcting the electron dose applied to each subfield in accordance with the line width of the mark 6 formed by reflecting the manufacturing process of (1), exposure for each subfield, which is the greatest feature of electron beam projection lithography, is performed. Accordingly, it is possible to correct the dimensional error between the subfields. Therefore, the merit of the exposure for each sub-field can be maximized, and the reliability of the dimensions for each sub-field, which cannot be achieved by batch transfer using a mask such as photolithography, can be improved.

Therefore, it is possible to suppress a minute dimensional variation in the reticle surface due to a macro production error of the reticle 3, and to suppress the subfields 4a, 4b, 4c, 4d.
It is possible to utilize the advantage of electron beam projection lithography that various controls can be performed for each shot.
Thereby, the variation of the circuit line width transferred onto the substrate 1 can be minimized by a method which cannot be performed in principle by optical projection lithography in one shot.

Therefore, it is possible to form a circuit pattern with higher line width accuracy without being affected by the pattern line width distribution in the plane of the reticle 3 during the manufacture of the reticle 3. This makes it possible to control, for example, the gate length with higher precision in the line-type pattern, and to suppress the occurrence of characteristic variations among the elements in the semiconductor integrated circuit. Also, in the hole pattern,
Since the dimensional controllability of the connection holes can be further improved, it is possible to suppress the occurrence of variations in the contact resistance, and it is possible to manufacture a semiconductor integrated circuit by more accurately controlling wiring delay and the like. .

In the above-described embodiment, an example in which the present invention is applied to exposure with an electron beam has been described. However, the present invention is not limited to this, and other charged particle beams such as an ion beam, X-rays, etc. The present invention can be applied to various types of exposure, including exposure by the following method.

[0055]

An embodiment in which this embodiment is specifically verified will be described below. The present invention is not limited by the following embodiments. At present, there is no device capable of performing the electron beam projection exposure while automatically correcting the exposure amount using the reticle 3. Therefore, in the embodiment described below, a single subfield (100 reticles on the reticle) is used.
0 μm × 1000 μm 250 in wafer exposure image
(μm × 250 μm).

The verification was performed using a reticle 3 whose line width was intentionally shifted by 10 nm (positive direction and negative direction, values on both sides) as a projection mask. FIG. 5 shows the reticle 3 used in the experiment. In FIG. 5, the pattern of the central sub-field 7 is a pattern having a reference line width,
The pattern of subfield 8 on the left has a line width of +10 nm
The shifted pattern and the pattern of the right subfield 9 are obtained by shifting the line width by -10 nm. That is, this reticle 3 has three subfields 7, 8,
9 is in the same reticle. In addition, EP
In an actual 8-inch wafer EPL reticle used for an L (Electron Beam Projection Lithograph) device,
Approximately 8000 subfields are arranged on one 8-inch wafer.

The reticle 3 is for a 100-nm device, and is in a state where no dimensional shift is performed, that is, in the central subfield 7 in FIG.
A logic gate pattern corresponding to the nm width is formed. Since the exposure uses a reticle four times the size of the pattern actually formed, the dimension on the reticle is 400 nm.

Hereinafter, Examples and Comparative Examples will be described. In the following Examples and Comparative Examples, Example 1 and Comparative Example 1 show the results using the reticle 3 in which the mark 6 is arranged in the non-exposed area 5 of the thin film 3a. Further, Example 2 and Comparative Example 2 show the results of using the reticle 3 in which the mark 6 is arranged at a portion on the back side of the beam 3b.

(Example 1) NEB-22 (a chemically amplified resist for a negative electron beam manufactured by Sumitomo Chemical Co., Ltd.) was placed on a 4-inch silicon wafer (substrate 1) which had been subjected to a surface hydrophobizing treatment with hexamethyldisilazane vapor. ) Was spin-coated so that the film thickness became 0.3 μm, and then soft-baked at a temperature of 110 ° C. for 90 seconds.

Then, using the electron beam projection exposure apparatus equipped with the reticle 3 described above, first, using the left sub-field 8, from the orientation flat side to the opposite side of the orientation flat, the left vertical 1. 0.5mm while increasing the exposure amount in a row
Exposure was performed at intervals. Here, the start exposure amount is 1
Exposure was increased to 1 μC / cm ² in one step at 5 μC / cm ² , and exposure was performed for a total of 25 shots.
Next, using the central sub-field 7, exposure is performed in the vertical direction in the center of the wafer in the same manner as in the case of the left side of the wafer. Exposure was performed in the same manner as in the center.

After the completion of the exposure, the wafer is heated to a temperature of 105 ° C. for 9 hours.
Post-exposure baking was performed for 0 second, paddle development was performed for 60 seconds with NMD-W (a developer containing a surfactant, manufactured by Tokyo Ohka), rinsed with pure water, and then post-baked at a temperature of 100 ° C. for 60 seconds.

The resist 3 has a thickness of 100 n on the substrate 1.
For a line width near m, the dimension per exposure dose 1 μC / cm ² is 3
The increase / decrease in nm was obtained as basic data. Among the patterns of the marks 6 placed in the non-exposed area 5 of the thin film 3b, the actual measured values of the 400 nm width pattern on the reticle 3 corresponding to the 1: 1.5 100 nm line & space on the substrate 1 were measured. Long SEM (S-8000 Pallet with attachment for mounting reticle manufactured by Hitachi, Ltd.)
409 nm in the left subfield 8, 398 nm in the center subfield 7,
In subfield 9 on the right side, it was 390 nm. Based on the measured values, of the 25 shots at the center of the wafer, the left column from the position of the optimum exposure amount of 30 μC / cm ² is 4 μC / cm ^2.
cm ² less adopted shot exposure and is 26μC / cm ^2, also the right column adopts ^shot 3 .mu.C / cm ² exposure intensive 33μC / cm ^2, the resist pattern in each shot (100 nm Logic (Gate pattern) was measured.

As a result, the following measurement data was obtained. Pattern in left subfield 8 (average of 10 points) 100 nm Pattern in center subfield 7 (average of 10 points) 100 nm Pattern in right subfield 9 (average of 10 points) 101 nm By shifting the amount, a pattern with less line width variation can be formed.

(Comparative Example 1) In Comparative Example 1, when performing electron beam projection exposure processing, as described in Embodiment 1, a shot whose exposure amount has been corrected based on the completed reticle line width is measured. Instead, the line width was measured without correction. That is, after the mark 6 for line width control placed on the reticle 3 is created, the exposure amount correction for line width control for each subfield based on the line width data is not performed at all, and the same exposure amount ( The line width of the shot exposed at 30 μC / cm ² ) was measured. Other conditions are
Data measurement was performed under the same conditions as in Example 1.

As a result, the following measurement data was obtained. Pattern in left subfield 8 (average of 10 points) 103 nm Pattern in center subfield 7 (average of 10 points) 100 nm Pattern in right subfield 9 (average of 10 points) 97 nm In the case where no was added, the variation (dimension error) of the line width clearly increased from that in Example 1.

(Embodiment 2) Next, Embodiment 2 will be described. In Example 2, the measurement was performed by arranging the mark 6 on the back side of the beam 3b without arranging the mark 6 to be used in the non-exposed area 5 of the actual film portion. Other conditions were the same as those in Example 1, and processing and measurement were performed.

Of the patterns of the marks 6 arranged on the back side of the beam 3b, 400 nm on the reticle 3 corresponding to a line and space of 1: 1.5 on the substrate 1 and 100 nm.
When the actual measurement value of the width pattern was measured by a length measuring SEM (using a pallet with an attachment for mounting a reticle manufactured by Hitachi S-8000), the left subfield 8 was measured.
402 nm, and 393n in the center subfield 7.
m, 381 nm in subfield 9 on the right.
Left column from the position of the optimum dose 30 .mu.C / cm ² of the 25 shots of the wafer center based on this measurement 3μ
C / cm ² less adopted shot exposure and is 27μC / cm ^2, also the right column employs a shot 4μC / cm ² exposure intensive 34μC / cm ^2, the resist pattern in each shot ( The line width of a 100 nm logic gate pattern) was measured.

As a result, the following measurement data was obtained. Pattern in left subfield 8 (average of 10 points) 101 nm Pattern in center subfield 7 (average of 10 points) 100 nm Pattern in right subfield 9 (average of 10 points) 102 nm Also in Example 2, the dimensional error was able to be suppressed to a range almost comparable to that of Example 1.

(Comparative Example 2) In Comparative Example 2, when performing electron beam projection exposure processing, as described in Example 2, a shot whose exposure amount was corrected based on the completed reticle line width was measured. Instead, the line width was measured without correction. That is, after creating the line width control mark 6 placed on the reticle 3, the exposure amount correction for line width control for each subfield based on the line width data is not performed at all, and the same exposure amount ( The line width of the shot exposed at 30 μC / cm ² ) was measured. Other conditions are
Data measurement was performed under the same conditions as in Example 2.

As a result, the following measurement data was obtained. Pattern in left subfield 8 (average of 10 points:
104 nm Pattern in the center subfield 7 (average of 10 points:
101 nm Pattern in right subfield 9 (average of 10 points:
(Point different from Example 1) 98 nm As described above, in the state where no correction is applied, the variation (dimension error) of the line width clearly increased from that of Example 2.

[0071]

Since the present invention is configured as described above, it has the following effects.

By providing a pattern for dimension measurement reflecting the manufacturing process of the exposure area corresponding to each of the exposure areas, it is possible to measure the dimensional error of the pattern formed in each exposure area. . This makes it possible to perform exposure with an appropriate electron dose corresponding to each exposure area. Therefore, it is possible to prevent a mutual error between the exposure regions of the projection mask from being reflected on the substrate to be exposed, and to form a pattern on the substrate with high accuracy.

By providing the pattern for dimension measurement in close proximity to each of the plurality of exposure areas, it is possible to ensure that the error factor in the process when forming the pattern of each exposure area of the projection mask is determined by the pattern for dimension measurement. And the pattern width of the exposure area can be accurately represented by the pattern for dimension measurement.

Further, by forming a pattern for dimension measurement outside the exposure region in the thin film region where the exposure region is formed, an error factor of the pattern width when forming the pattern of the exposure region is reduced. It can be reflected on the pattern for dimension measurement with very high accuracy.

By providing a pattern for dimension measurement at the position of the beam dividing each exposure area, even when there is a restriction in providing a pattern for dimension measurement in a thin film portion close to the exposure area, a projection mask is required. A pattern for dimension measurement can be provided thereon.

By forming the pattern for dimension measurement into a convex shape or a concave shape, it becomes possible to form the pattern for dimension measurement simultaneously with the process of forming the pattern of the exposure region by etching.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a state in which a substrate is irradiated with an electron beam using a projection mask according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the vicinity of a subfield shown in FIG. 1 in detail.

FIG. 3 is a schematic perspective view showing a state in which a projection mask is overlooked from above in FIG. 2;

FIG. 4 is a plan view showing a pattern shape of a representative dimension measurement mark.

FIG. 5 is a plan view showing a reticle used in a specific embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 1 substrate, 2 first forming aperture, 3 reticle (projection mask), 3 a beam, 3 b thin film, 4 a,
4b, 4c, 4d, 7, 8, 9 subfields, 5
Unexposed area, 6 marks.

Claims (14)

[Claims] 1. A projection mask for selectively exposing a substrate by transmitting an electron beam, comprising: a plurality of exposure regions in which a predetermined pattern for exposing the substrate is formed; A dimension measurement pattern formed close to each of the regions. 2. A thin film on which the plurality of exposure regions are formed, and a beam formed on a boundary between adjacent exposure regions, wherein the pattern for dimension measurement is the exposure region in a region of the thin film. The projection mask according to claim 1, wherein the projection mask is formed outside. 3. A thin film on which the plurality of exposure regions are formed, and a beam formed at a boundary between the adjacent exposure regions, wherein the pattern for dimension measurement is formed at a position of the beam. The projection mask according to claim 1, wherein: 4. A pattern according to claim 1, wherein said pattern for dimension measurement is formed in a convex shape or a concave shape.
The projection mask according to any one of the above. 5. The projection mask according to claim 2, wherein the pattern for dimension measurement is constituted by holes penetrating the thin film. 6. The pattern according to claim 1, wherein the pattern for dimension measurement is a linear pattern, a block-shaped pattern, or a pattern in which a plurality of these patterns are arranged. A projection mask according to any of the above. 7. The pattern for dimension measurement corresponding to one exposure area is formed of at least two or more patterns having different line widths.
7. The projection mask according to any one of claims 1 to 6. 8. A method for selectively exposing a substrate using a projection mask having a plurality of exposure regions, wherein a representative dimension corresponding to a pattern formed in the exposure regions is detected for each of the exposure regions. An electron beam exposure method, comprising: a first step; and a second step of correcting an electron dose to be applied to each of the exposure regions based on the detected representative dimension. 9. The electronic device according to claim 8, wherein, in the first step, the representative dimension is detected by using a dimension measurement pattern formed corresponding to each of the plurality of exposure regions. Line exposure method. 10. In the first step, the representative dimensions corresponding to each of the plurality of exposure regions are collectively detected, and the electron beam of the corrected electron dose is sequentially applied to each of the plurality of exposure regions. 10. The electron beam exposure method according to claim 8, wherein irradiation is performed. 11. Each time the representative dimension corresponding to one exposure area is detected in the first step, the correction in the second step is performed, and the exposure area is irradiated with an electron beam. The electron beam exposure method according to claim 8 or 9, wherein 12. An electron beam exposure apparatus for irradiating an electron beam onto a substrate using the projection mask according to claim 1. Description: 13. A semiconductor device manufactured using the projection mask according to claim 1. Description: 14. A method of manufacturing a semiconductor device, comprising manufacturing a semiconductor device using the electron beam exposure method according to claim 8.