JPH07140643A - Aperture manufacturing method - Google Patents

Abstract

(57) [Summary] [Object] To provide a method of manufacturing an aperture for a charged beam exposure apparatus which is easy to manufacture and has high accuracy. A method for manufacturing an aperture 9 used in an exposure method using a charged beam, which has conductivity such as S
On the supporting substrate 1 made of i single crystal, a material having a thermal expansion coefficient substantially equal to that of the supporting substrate, high conductivity, and not chemically immersed in the etching solution of the supporting substrate, for example, a metal film 6 such as Pt is formed. Then, the metal film 6 is partially removed by the ion beam 13 to form a metal film pattern 7, and then back etching is performed from the back surface side of the support substrate 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an aperture in a so-called collective exposure type charged beam exposure apparatus used for forming a fine pattern of a semiconductor integrated circuit or the like, and particularly, a high density repetitive pattern preparation. The present invention relates to a method for manufacturing an aperture of a charged beam exposure apparatus in which the beam forming means is improved in order to improve the drawing speed.

[0002]

2. Description of the Related Art The pattern of a semiconductor integrated circuit tends to be miniaturized year by year and has become complicated. In order to draw and form such a pattern with a charged beam exposure apparatus, a method of drawing repeatedly used figures and figure groups in one shot, so-called collective exposure method, block exposure method, character projection method, etc. Has been proposed.

In this system, the aperture in the charged beam exposure apparatus is changed to one in which a round hole is formed in the conventional point beam system and a rectangular hole is formed in the variable shaped beam system, and a figure or a pattern used repeatedly is used. A drastic improvement in throughput is expected with the idea that drawing is performed in a single shot by creating a group of figures.

By the way, in the aperture used in this system, conventionally, for example, as shown in FIG. 3 (j), a thick Si substrate 12 is used as a supporting substrate to perform chemical etching according to the azimuth plane from the back side, and the upper surface thereof is subjected to chemical etching. A thin Si substrate 11 bonded together, or a thick Si substrate as shown in FIG.
The substrate 1 is chemically etched from the back according to the azimuth plane, the upper surface is made thin, and a figure and a figure group that are repeatedly used are formed in that portion.

However, in the method of FIG. 3, as shown in FIG. 3A, first, the Si substrate 1 which is a supporting substrate is prepared,
As shown in (b), a masking pattern 2 is formed on the back surface of the supporting substrate, and as shown in (c), chemical etching is performed using a Si etching solution 4 (reference numeral 3 is an etching bath) to obtain Si. An upper surface Si substrate 11 is bonded onto the substrate 12 via the Si oxide film 10 as shown in (f), and the Si substrate 11 on the upper surface is polished or etched to an appropriate thickness, as shown in (g). A resist 14 is applied thereon, and a pattern is exposed with light or an electron beam as shown in (h), followed by development treatment to form a resist pattern 15, and then as shown in (i). There is a step of etching the Si substrate 11 and removing the resist. Further, in the method of FIG. 4, the Si substrate 1 which is a supporting substrate is prepared as shown in FIG. 4A, and the masking pattern 2 is formed on the back surface as shown in FIG.
Chemical etching is carried out, and then this chemical etching is carried out until the upper surface has an appropriate thickness as shown in (c), a resist 14 is applied thereon as shown in (d), and as shown in (e). After patterning this to form a resist pattern 15, there is a step of etching the substrate on the upper surface and stripping the resist as shown in (f), which is complicated in both the methods of FIG. 3 and FIG. Required a different process.

Further, in the method of FIG. 3, the Si substrate 11 on the upper surface is used.
Heating at the time of bonding the Si substrate 12 and the lower Si substrate 12, and the Si oxide film 1 between the Si substrate 11 and the Si substrate 12.
Since stress is generated by passing through 0, the pattern is distorted, and there is a problem that the bonding process is complicated due to the stress control.

In both of the methods shown in FIGS. 3 and 4, the upper surface is thinned and then etching is performed. Therefore, the thickness is several tens to several hundreds of μm, so that handling should be performed with particular care, especially in resist coating. There is a problem that the thin film portion on the upper surface is easily broken due to the weight of the resist at this time, the weight of the etching solution at the time of wet etching, the vibration and the impact during the handling during the process. Also, when thinning the upper surface by chemical etching, the film thickness of the upper surface varies depending on when etching is stopped,
There is a problem in that very precise etching control is required.

By the way, the distortion of the pattern is caused by deformation of the pattern, that is, a pattern different from the intended pattern is formed on the aperture and is formed as a transfer pattern, or the positional deviation of the pattern, that is, the intended pattern on the aperture. For example, a pattern may be formed at a position different from the position and may be formed as a transfer pattern, and the degree of the deviation may be several tenths of μm to several μm. If the pattern is transferred onto the semiconductor wafer in this state, it becomes a serious defective product, and it is obvious that the manufactured product does not operate as an integrated circuit.
Therefore, conventionally, the flatness of the finished substrates is measured one by one after the bonding is completed.

Further, when the aperture is incorporated in the charged beam exposure apparatus to perform exposure, the portion shielded by the aperture, that is, the portion having no pattern is irradiated with the charged particle beam. Therefore, when the material of the aperture is a substance having poor electric conductivity, charge-up may occur. When the charge-up occurs, the beam formed by the aperture is deformed, and the beam is displaced from the intended position. In the worst case, there is a problem that no pattern is drawn.

Particularly, in the case of the bonding method shown in FIG.
Charge-up is an unavoidable problem because it is via the oxide film 10. Therefore, conventionally, a method such as forming a conductive film on the upper or lower part has been taken, but since the film has a multi-layer structure, the problem that the process becomes complicated occurs,
In addition, since the coefficient of thermal expansion differs for each layer, there is a problem that stress is applied and the pattern is distorted as described above.

[0011]

Therefore, in the present invention, there is a problem with the aperture for a charged beam exposure apparatus that has been used in the conventional exposure method for a charged beam, which is a so-called collective exposure method, that is, a portion where a pattern is formed. Since it is a thin film, stress is generated during production, the pattern to be formed is distorted or requires careful handling, and after taking measures to prevent the thin film portion from being easily shaken during pattern production, A so-called lithography process is performed to create a pattern, which makes the process complicated.
There is a possibility that charge-up may occur during irradiation of the charged particle beam, and the upper and lower support substrates are made of the same material S.
Therefore, it is an object of the present invention to provide a method of manufacturing an aperture for a charged beam exposure apparatus, which is easy to manufacture and has high accuracy, by solving problems such as a complicated step required for pattern etching because of i.

[0012]

In order to achieve the above object, the method for manufacturing an aperture according to the present invention is used in an exposure method using a charged beam, and includes a first film region having an opening and the first film region. A second film region that supports the first film region and is thicker than the first film region, and a main material that forms the first film region and a main material that forms the second film region. In the manufacturing method of the aperture made of different materials,
(A) forming the first film region on the second film region, (b) forming a pattern by partially removing the first film region, and (c) the first film region. It is characterized in that the second film region is etched.

The method of manufacturing the aperture of the present invention is
The pattern formed in the first film region is formed by an ion beam or a laser beam.

The aperture manufacturing method of the present invention is
The first film region is not etched when the second film region is etched.

The method of manufacturing the aperture of the present invention is
It is characterized in that the first film region is made of a conductive metal.

The method of manufacturing the aperture of the present invention is
The difference in the coefficient of linear thermal expansion between the materials used in the first film region and the second film region is 273K to 373.
It is characterized in that it is 5 × 10 ⁻⁶ K ⁻¹ or less in the temperature range of K.

Furthermore, the aperture manufacturing method of the present invention is characterized in that the second film region is made of Si single crystal.

[0018]

According to the present invention, a metal film, such as Pt, which has a high conductivity and is chemically conductive when the supporting substrate is etched, is formed on the second film region which is the supporting substrate made of single crystal Si or the like. Patterning area using a material that is not
Forming a pattern by partially removing the first film region with an ion beam or the like to form a pattern, the thickness control of the first film region on the upper surface is simplified, Since it is not necessary to form a resist pattern when patterning the first film region, the process can be simplified and the substrate can be easily handled during the process.

Further, since there is no step of bonding by thermal adhesion, it is possible to reduce the generation of stress and prevent the distortion of the pattern due to it.

Further, according to the present invention, since the insulator is not included, it is possible to realize a configuration in which charge-up due to irradiation of an electron beam or the like does not occur.

[0021]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of the present invention in the order of steps.

First, as shown in FIG. 1 (a), the thickness is 500 μm.
m Si single crystal substrate 1 was prepared. The plane orientation of this substrate was (100).

Next, as shown in FIG. 1B, a metal film 6 is formed on the upper surface of the above-mentioned substrate 1 by a vacuum evaporation method. The thickness of the metal film 6 is generally 20 μm or less, preferably 5 to 1
It is 5 μm. The film thickness of the metal film 6 becomes the thickness of the pattern formation region that shields the electron beam when completed. The metal film is a material whose thermal expansion coefficient is as close as possible to that of Si which is a supporting substrate, specifically, a material whose difference in thermal expansion coefficient is 5 × 10 ^-6 K ^-1 or less in the temperature range of 273K to 373K. And S
It is desirable that it is not exposed to the etching solution of i, and Pt is used in this embodiment. Besides Pt, Pd, an alloy of Pt and Pd, or the like can be used. For forming the metal film 6, a conventionally known method such as a sputtering method or an ion plating method may be used.

Next, as shown in FIG. 1C, the metal film pattern 7 is formed. In this embodiment, the metal film pattern 7 is formed by partially removing the metal film 6 based on the pattern data produced by CAD by using a conventionally used focused ion beam device (FIB 611 made by FEI). Form.

In the figure, reference numeral 13 indicates an ion beam.

In the present invention, it is particularly preferable to use an ion beam focused to a diameter of 1 μm or less because fine and free machining can be performed. The feature of the focused ion beam method lies in the ion source used, but in a focused ion beam apparatus using, for example, a liquid metal ion source as this ion source, an ion beam of up to 100 KV is focused to a diameter of about 0.1 μm and is used as a target. Can be driven into.

The metal film pattern 7 can be formed by converging a high-power excimer laser or the like instead of the above-mentioned ion beam.

Next, back etching is performed from the back surface side of the substrate 1 with a heated KOH solution, that is, the etching solution 4.
At this time, as shown in FIG. 1D, a masking pattern 2 is previously formed on the back surface in a portion other than the opening.
The size of this opening is arbitrary, but if the area is too large, it will break easily when completed, so 500 μm
A corner is preferable. At this time, the plane orientation of the substrate is (10
Therefore, as shown in FIG. 1D, so-called anisotropic etching is performed in which the etching progresses in the thickness direction with respect to the substrate, but does not progress so much in the lateral direction. Become. The thickness of the opening is 10 for etching.
Stop at a thickness of about 0 μm, that is, a thickness that does not easily break in the subsequent steps. After that, cleaning is performed with pure water. The masked portion other than the opening, that is, the masking pattern 2 is not peeled off at this stage.

This back etching step may be performed before the above-mentioned metal film pattern 7 is formed.

Next, as shown in FIG. 1E, the above-mentioned substrate is immersed in a heated KOH solution which is an etching solution 4 for Si. The etching liquid 4 permeates from the upper surface and the lower surface of the substrate. Although the metal film 6 is formed on the upper surface,
Since this portion is not chemically attacked by the etching solution 4, the lower substrate Si is not etched. However, since Si of the substrate is exposed in the holes of the metal film pattern 7 described above,
The etching solution 4 permeates and dissolves.

On the other hand, with respect to the back surface, the back etching in the step (d) is continued, and finally Si of the substrate remains only in the portion where the masking pattern 2 is formed, and the opening is formed from the upper surface. Only the formed metal film pattern 7 remains to form a pattern region 8.

After that, the masking pattern 2 is peeled off, washed with pure water and dried to complete the aperture 9 of the present invention as shown in FIG. 1 (f).

According to the present embodiment, since there is no conventional bonding step, it is not necessary to apply high heat to the substrate, so that stress is not generated and the pattern is neither distorted nor displaced. At the time of pattern formation, conventionally, a resist is applied,
A series of steps of baking a pattern with light or an electron beam, developing it, etching the substrate below it, and peeling off the resist is completed by only drawing with an ion beam. Simplified to.
Further, the back etching process of the substrate does not require precise control of etching as in the conventional case, so that the process is simplified as compared with the conventional case.

Further, when the aperture prepared in this example was attached to a charged particle beam exposure apparatus and drawing was performed,
Even when the pattern was drawn for a long time, the charge-up that had occurred in the past did not occur, and no pattern distortion or displacement due to stress was confirmed.

FIG. 2 is a sectional view showing another embodiment of the present invention in the order of steps.

The same parts as those in FIG. 1 are designated by the same reference numerals, and the duplicate description will be omitted as appropriate.

First, as shown in FIG. 2A, the thickness is 500 μm.
An m single-crystal Si substrate 1 is prepared. The plane orientation of this substrate is (100).

Next, back etching is performed from the back surface side of the substrate 1 with the etching solution 4. At this time, as shown in FIG. 2B, the masking pattern 2 is formed in advance in a portion other than the opening. At this time, the plane orientation of the substrate 1 is (1
00), the so-called anisotropic etching described above is performed as shown in FIG. The etching is stopped at a plate thickness of the opening portion of about 100 μm, that is, a thickness that does not easily break in the subsequent steps. afterwards,
Wash with pure water. The masking pattern 2 is not peeled off because it is required in a later step. With this,
Aperture blank 5 is completed as shown in (d).

Note that this step may be performed after the formation of a pattern described later.

Next, as shown in FIG. 2E, a metal film 6 is formed on the surface of the blank 5 opposite to the opening, by the same method as in the above-mentioned embodiment.

Next, as shown in FIG. 2F, the metal film pattern 7 is formed. The metal film pattern 7 is formed using the above-mentioned focused ion beam device or the like.

Next, as shown in FIG. 2 (g), Si, which is the support substrate 1, is etched. A reactive ion etching apparatus (CSE-1 manufactured by Nippon Vacuum Technology Co., Ltd.) which has been conventionally used for a substrate on which the above-described metal film pattern 7 is formed
110) is used to etch to a depth of 10 μm. At this time, in this embodiment, the power is set to 200 W and Cl
A gas obtained by adding 10% of SF ₆ to ₂ is used.

At this time, the portion where the metal film pattern 7 is formed is not chemically etched by the etching gas and is not etched. However, since Si of the substrate is exposed in the hole of the metal film pattern 7, only this portion is etched.

Next, the substrate is taken out from the above-mentioned ion etching apparatus and immersed in a Si etching solution 4 as shown in FIG. On the upper surface, the etching solution 4 permeates through the openings of the metal film pattern 7 and the etching proceeds in the vertical direction. Also in this case, since the etching is anisotropic as described above, the etching does not proceed so much in the lateral direction. For the back surface, back etching is continued in the manufacturing process of the blank 5 described above. When the opening of the upper surface metal film pattern 7 and the opening of the back surface are finally connected, the etching is stopped. At this time, the total thickness of the metal film remaining without being etched and the supporting substrate Si was 15 μm. Further, the cross-sectional shape thereof was tapered as shown in FIGS. 2 (h) and 2 (i).

After that, the masking pattern 2 is peeled off, washed with pure water and dried to complete the aperture 9 of the present invention as shown in FIG. 2 (i).

According to this embodiment, like the above-mentioned embodiments,
Since there is no bonding step that has been conventionally performed, it is not necessary to apply high heat to the substrate, so that stress is not generated and pattern distortion or displacement does not occur. Since the pattern production is completed only by drawing with an ion beam or the like, the process is simplified. In addition, the blank production process does not require precise control of the back etching of the substrate, which also simplifies the process. It was

Further, when the apertures produced in this example were also mounted on a charged particle beam exposure apparatus and writing was performed, the charge-up that was conventionally caused does not occur even when writing is performed for a long time, and it is caused by stress. No pattern distortion or deviation was confirmed.

[0049]

According to the aperture manufacturing method of the present invention, the pattern of the first film region made of a metal film or the like can be formed without forming a resist pattern, and the support substrate made of Si or the like can be formed. Since the film thickness can be easily controlled during etching of the second film region, the process can be simplified, which is an excellent effect.

The first pattern forming region on the upper surface
Since the film region has a property that it is not attacked by the etching liquid or etching gas of Si, which is the supporting substrate, the supporting substrate can be etched using the pattern as a mask. In this respect also, the process can be shortened. Produce an effect.

Further, since there is no conventional bonding step by thermocompression bonding, it is possible to reduce stress generation and prevent pattern distortion.

Further, according to the present invention, since the insulator is not included, even if the aperture is mounted in the charged beam exposure apparatus and exposure is performed, the charge-up of the aperture does not occur.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention in the order of steps.

FIG. 2 is a cross-sectional view showing another embodiment of the present invention in the order of steps.

FIG. 3 is a cross-sectional view showing an example of a conventional aperture manufacturing method in process order.

FIG. 4 is a cross-sectional view showing another example of the conventional method of manufacturing an aperture in the order of steps.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Si substrate 2 Masking pattern 3 Etching tank 4 Si etchant 5 Aperture blank 6 Metal film 7 Metal film pattern 8 Pattern area 9 Aperture 10 Si oxide film 11 Upper Si plate 12 Lower Si plate 13 Ion beam 14 Resist 15 Resist pattern

Claims (6)

[Claims] 1. A first film region having an opening, which is used in an exposure method using a charged beam, and a second film which supports the first film region and is thicker than the first film region. And a main material forming the first film region and a main material forming the second film region are made of different materials. (A) The second film region Forming a pattern by forming the first film region on the upper surface, and (b) partially removing the first film region,
(C) After that, the method for manufacturing an aperture is characterized in that the second film region is etched. 2. The method for manufacturing an aperture according to claim 1, wherein the pattern formed in the first film region is formed by an ion beam or a laser beam. 3. The method of manufacturing an aperture according to claim 1, wherein the first film region is not etched when the second film region is etched. 4. The method for manufacturing an aperture according to claim 1, wherein the first film region is a metal having conductivity. 5. The first film region and the second film region
The difference in linear expansion coefficient due to the heat of the materials used is 27
5 × 10 in the temperature range of 3K to 373K^-6 K^-1Since
It is below, It is in any one of Claim 1 thru | or 4 characterized by the above-mentioned.
A method for manufacturing the described aperture. 6. The method for manufacturing an aperture according to claim 1, wherein the second film region is made of Si single crystal.