JPH07152149A - aperture - Google Patents

Abstract

PURPOSE:To eliminate the charge-up of an aperture and to facilitate production by imparting a layer consisting of a material having the electric conductivity higher than the electric conductivity of a main material forming the aperature to a first region. CONSTITUTION:A metallic film 8 is formed atop an Si single crystal substrate 1 by a vacuum vapor deposition method. The film thickness of this metallic film 8 is the thickness of a pattern forming region shielding electron beams at the time of completion. The metallic film 8 consists preferably of the material which has the electric conductivity higher than the electric conductivity of the main material of the aperture, i.e. Si which is a supporting substrate, and is not attacked by an etching liquid 4 for the Si. Ti is used in this embodiment. Next, the formation of the metallic film pattern 8a is executed and back etching is executed with the heated etching liquid 4 which is a KOH soln. from the rear surface side of the substrate 1. Further, the substrate is immersed into the heated KOH soln. which is the etching liquid 4 for the Si. Peeling of the masking pattern 2 is thereafter executed and the pattern is washed by pure water and dried, by which the aperture 9 is completed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aperture in a so-called batch exposure type charged beam exposure apparatus used for forming a fine pattern of a semiconductor integrated circuit or the like. The present invention relates to an aperture of a charged beam exposure apparatus in which a beam forming means is improved for the purpose of improvement.

[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. 4 (j), a thick Si substrate 12 is used as a supporting substrate and chemical etching is performed from the back in accordance with the azimuth plane. 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. 4, as shown in FIG. 4A, 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. 5, a Si substrate 1 which is a supporting substrate is prepared as shown in FIG. 5A, and a masking pattern 2 is formed on the back surface as shown in FIG.
Chemical etching is then performed, and then the upper surface is chemically etched or polished until the upper surface has an appropriate thickness as shown in (c), and the resist 14 is formed thereon as shown in (d).
And then patterning this as shown in (e) to form a resist pattern 15, and then etching the substrate on the upper surface as shown in (f) to remove the resist. In any of the methods shown in FIGS. 4 and 5, complicated steps are required.

In the method of FIG. 4, the Si substrate 11 on the upper surface is also 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 systems shown in FIGS. 4 and 5, the upper surface is thinned and then etching is performed. Therefore, the thickness is several tens to several hundreds of μm. 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 at the time of 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.

Further, when the aperture having this structure is incorporated into the charged beam exposure apparatus to perform exposure, the portion shielded by this aperture, that is, the portion having no pattern is
The charged beam is irradiated. Therefore, when the material of the aperture is a substance having poor electric conductivity, charge-up may occur.

In particular, since the conventional aperture is made of only Si, its electrical resistivity is about 2.3 × at room temperature.
It is as high as 10 ⁴ Ω · cm. Further, in the case of the bonding method as shown in FIG. 4, it is a well-known fact that the electrical resistivity is significantly higher than that of Si because the Si oxide film is interposed in the bonding portion.

Therefore, if charge-up occurs,
There is a problem that the beam formed by the aperture is deformed and is displaced from an intended position, and in a severe case, a pattern is not drawn at all.

[0011]

SUMMARY OF THE INVENTION Therefore, the present invention has a problem with the aperture for a charged beam exposure apparatus that has been conventionally used in a so-called collective exposure method of a charged beam exposure method, that is, the conductivity of the aperture is poor. Therefore, the problem that charge-up occurs, the beam formed by the aperture is deformed, and the pattern is not drawn at all, is solved, and the aperture for a charged beam exposure apparatus that is easy to manufacture and has high accuracy is solved. Is intended to provide.

[0012]

In order to achieve the above object, the aperture of the present invention is used in an exposure method using a charged beam, and has a first film region having an opening and the first film region.
A second film region thicker than the first film region and supporting the film region of the first film region, the first film region having a higher conductivity than a main material forming the aperture. Is added to at least one layer.

Further, the aperture of the present invention is characterized in that the layer made of a substance having a conductivity higher than that of the main material is a material which is not etched when the main material is etched.

Further, in the aperture of the present invention, the first film region is composed only of a layer made of a substance having a conductivity higher than that of the main material, and the second film region is composed of the main material. Is characterized by.

The aperture of the present invention is characterized in that the second film region is made of Si single crystal.

Further, the aperture of the present invention is characterized in that the main material is Si single crystal.

Further, in the aperture of the present invention, the substances having higher conductivity than the main material are Cu, Pt, Ag,
W, Mo, Fe, Cr, Pd, Ti, Nb, In, Sn
Alternatively, it is characterized by being at least one selected from compounds containing them as one component.

[0018]

According to the aperture of the present invention, the aperture is composed of the first film region having the opening and the second film region which is the supporting substrate of the first film region, and is more than the main material forming the aperture. At least one layer made of a material having high conductivity,
Since it is provided in the first film region, when the main material is Si and the material of the layer having high conductivity is Ti, for example, the conductivity of Ti is about 5 × 10 ⁸ times that of Si. Since the electrons generated during beam irradiation flow from the layer having high conductivity to the ground, charge-up does not occur.

Further, in the aperture of the present invention, the step of thinning the upper surface of the aperture and the step of patterning the thinned portion, which have been conventionally performed, can be simplified and can be easily manufactured.

[0020]

Embodiments Embodiments of the aperture of the present invention will be described below with reference to the drawings, but it goes without saying that the present invention is not limited to the embodiments.

<Embodiment 1> FIG. 1 is a sectional view showing an aperture according to an embodiment of the present invention in the order of manufacturing steps.

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

Next, as shown in FIG. 1B, a metal film 8 is formed on the upper surface of the above-mentioned substrate 1 by a vacuum evaporation method. The thickness of the metal film 8 is generally 20 μm or less, preferably 5 to 1
It is 5 μm. The film thickness of the metal film 8 becomes the thickness of the pattern formation region that shields the electron beam when completed. It is desirable that the metal film 8 has higher conductivity than the main material of the aperture, that is, Si that is the supporting substrate, and that it is not exposed to the Si etching solution 4. In this embodiment, Ti is used. Besides Ti, Cu, Pt, W, Mo, Fe, Cr,
Pd, Ag, Nb, In, Sn or a compound containing them as one component can also be used. For forming the metal film 8, a conventionally known method such as a sputtering method, an ion plating method, or a plating method may be used.

Next, as shown in FIG. 1C, the metal film pattern 8a is formed. In this embodiment, the metal film pattern 8a is formed by partially removing the metal film 8 based on the pattern data produced by CAD by using a conventionally used focused ion beam device (FIB611 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 metal film pattern 8a 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 an etching solution 4 of a heated KOH solution. 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 the opening is arbitrary, but if the area is too large, the opening is likely to break at the time of completion. Therefore, it is preferably about 500 μm square. At this time, since the plane orientation of the substrate is (100), the etching progresses in the thickness direction with respect to the substrate as shown in FIG. There is no so-called anisotropic etching. For etching, the thickness of the opening is 100 μm
The thickness is set so that it does not easily break in the subsequent steps. After that, cleaning is performed with pure water. The masking pattern 2 other than the openings is masked,
It does not peel at this stage.

This back etching step may be performed before the above-mentioned metal film pattern 8a 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 8 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 the Si of the substrate is exposed in the holes of the metal film pattern 8a, the etching solution 4 permeates and dissolves.

On the other hand, with respect to the rear 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. Metal film pattern 8a
Only remains.

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).

When the aperture prepared in the present embodiment was mounted on a charged particle beam exposure apparatus and writing was performed, charge-up which was conventionally generated does not occur even when performing drawing for a long time, and the drawing pattern is deformed. Was not confirmed.

Further, according to the present embodiment, since there is no bonding step which has been conventionally performed, 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 series of steps of coating a resist, baking the pattern with light or an electron beam, developing it, etching the substrate underneath, and peeling the resist is performed by using an ion beam or the like. The process is greatly simplified because only drawing is completed.

<Embodiment 2> FIG. 2 is a sectional view showing an aperture according to another embodiment of the present invention in the order of manufacturing steps. In addition, the same parts as those in FIG.

First, as shown in FIG. 2A, the thickness 500
A substrate 1 of Si single crystal of μm is prepared. The plane orientation of this substrate is (1, 0, 0).

Next, back etching is performed from the back surface side of the substrate 1 with an etching solution 4 of a heated KOH solution. At this time, as shown in FIG. 2B, the masking pattern 2 is formed in a portion other than the opening. At this time, since the plane orientation of the substrate is (1, 0, 0), so-called anisotropic etching is performed on the substrate as shown in FIG. For etching, the thickness of the opening is 100 μm
The thickness is set so that it does not easily break in the subsequent steps. After that, cleaning is performed with pure water. The masking pattern 2 other than the openings is masked,
It does not peel at this stage. This completes the aperture blank 5 as shown in FIG. 2 (d).

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

Next, as shown in FIG. 2E, an electron beam resist 6 (C manufactured by Tosoh Co., Ltd.) is formed on the surface of the blank 5 opposite to the opening.
Apply MS-EX (R). The film thickness at this time is 20
μm or less. The thickness is preferably 5 to 15 μm. This film thickness becomes the thickness of the pattern formation region that shields the electron beam when completed.

After the predetermined pre-baking process, a conventionally used electron beam drawing apparatus (HL-700 manufactured by Hitachi, Ltd.) is used to draw a pattern, and a predetermined developing and post-baking process is performed. As a result, a resist pattern 7 is completed on the upper surface of the blank 5, as shown in FIG.

Next, on the resist pattern 7 described above, as shown in FIG.
As shown in (g), the metal film 8 is formed by the vacuum evaporation method.
In this embodiment, Ti is used as the material of the metal film 8 as in the previous embodiments. At this time, the thickness of the metal film 8 is about the thickness of the resist pattern 7, that is, vacuum deposition is performed until the openings of the resist pattern 7 are filled with the metal film 8. The metal film 8 may be formed by the above-mentioned sputtering method, ion plating method, plating method or the like.

Next, as shown in FIG. 2H, the substrate on which the above-mentioned metal film 8 has been formed is dipped 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.

Regarding the upper surface, the metal film 8 is also formed on the resist pattern 7, but the metal film 8 is not attached at the boundary between the resist pattern 7 and the opening filled with the metal film 8. It is a thin film, and the etching liquid 4 penetrates from that portion. Since the etching solution 4 is strongly alkaline, it dissolves the resist pattern 7, that is, the electron beam resist 6. Therefore, the resist pattern 7 and the metal film 8 on it are peeled off, and Si underneath is dissolved. However, since the metal film 8, that is, Ti, is insoluble in the etching solution 4, the metal film 8 other than on the resist pattern 7 remains and forms the metal film pattern 8a.

On the other hand, regarding the lower surface, the blank 5 described above is used.
The back etching in the manufacturing process of 1), that is, anisotropic etching is performed, and finally Si remains only in the masking pattern 2 portion, and only the metal film 8 formed from the upper surface remains in the opening of the blank 5.

After this, 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).

When the apertures produced in this example were mounted on a charged particle beam exposure apparatus and writing was performed, charge-up that had been conventionally caused did not occur even when writing was performed for a long time, and the drawing pattern was deformed. Was not confirmed.

In these embodiments, the thin film portion above the aperture is made of only a substance having a high conductivity, but the aperture of the present invention has at least one layer made of a substance having a high conductivity in the thin film portion. I don't care. For example, a polysilicon film and Ti or A having higher conductivity
A laminated structure composed of g and Ti may be used.

<Embodiment 3> FIG. 3 is a sectional view showing an aperture according to another embodiment of the present invention in the order of manufacturing steps. In addition, the same parts as those in FIG.

First, as shown in FIG. 3A, the thickness 500
A substrate 1 of Si single crystal of μm is prepared. The plane orientation of this substrate is (1, 0, 0).

Next, back etching is performed from the back surface side of the substrate 1 with the etching solution 4. At this time, as in the case of FIG.
As shown in (b), a masking pattern is formed in advance in a portion other than the opening. At this time, since the plane orientation of the substrate 1 is (1, 0, 0), so-called anisotropic etching is performed on the substrate as shown in FIG. For etching, the thickness of the opening is 100μ
Stop at a thickness of about m, that is, a thickness that does not easily break in the subsequent steps. After that, cleaning is performed with pure water. The masking pattern 2 masked except for the openings is not peeled off. With this, the blank 5 is completed as shown in FIG. Similar to the above embodiment, this step may be performed after formation of a pattern described later.

Next, as shown in FIG. 3E, the electron beam resist 6 (CMS-EX (R) manufactured by Tosoh Corporation) is applied to the surface of the blank 5 opposite to the opening. The film thickness at this time is
It was 5 μm.

Next, after a predetermined pre-baking process, a pattern is drawn by the electron beam drawing device (HL-700 manufactured by Hitachi, Ltd.), and a predetermined development and post-baking process are performed, as shown in FIG. 3 (f). A resist pattern 7 is formed on the upper surface of the blank 5.

Next, a metal film 8 is formed on the resist pattern 7 as shown in FIG. 3 (g). The thickness of this metal film 8 was 5 μm. The total film thickness of the metal film 8 and the Si below it becomes the thickness of the pattern forming region that shields the electron beam when completed. The thickness is preferably 5 to 15 μm.

As the material of the metal film 8, Ti is used as in the above embodiment.

At this time, the thickness of the metal film 8 is the thickness of the resist pattern 7, that is, the opening of the resist pattern 7 is filled with the metal film 8. As described above, the metal film 8 is formed by the vacuum evaporation method, the sputtering method, the ion plating method, the plating method, or the like.

Next, the above substrate is immersed in a stripping solution for the electron beam resist 6 as shown in FIG. 3 (h). Then, only the resist pattern 7 is dissolved, the metal film 8 in a portion where the resist pattern 7 is not formed is not dissolved, and the metal film pattern 8a is formed.

Next, as shown in FIG.
A certain Si is etched. That is, the above metal
The substrate on which the film pattern 8a is formed is conventionally used.
Reactive ion etching equipment (made by Nippon Vacuum Technology Co., Ltd.
CSE-1110) and a 10 μm deep etch
Perform At this time, in this embodiment, the power is set to 200.
W and Cl ₂To SF ₆Use a gas with 10% added
It

At this time, the portion where the metal film 8 is formed is not chemically etched by the etching gas and is not etched. However, the holes of the metal film pattern 8a are
Since i is exposed, only this portion is etched.

Next, the substrate is taken out from the above-mentioned ion etching apparatus and immersed in the Si etching solution 4 as shown in FIG. 3 (j). On the upper surface, the etching liquid 4 permeates through the openings of the metal film pattern 8a 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 8a 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 Si was 15 μm. The cross-sectional shape thereof was tapered as shown in FIGS. 3 (j) and 3 (k).

Then, 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. 3 (k).

When the apertures produced in this example were also mounted on the charged particle beam exposure apparatus and writing was performed, the charge-up that had been conventionally caused did not occur even when the writing was performed for a long time, and the writing pattern No deformation was confirmed.

[0062]

As described in detail above, according to the aperture of the present invention, a substance having a higher conductivity than the main material forming the aperture is formed in the first film region which is the pattern formation region above the aperture. Since at least one layer consisting of is formed, the charge-up of the aperture, which has conventionally occurred when the beam exposure is performed, does not occur, and as a result, the deformation of the drawing pattern does not occur.

According to the aperture of the present invention, when the main material of the aperture is, for example, Si, the conductivity is high as the first film region which is the pattern formation region, and Si is
By using a substance that is not chemically attacked during the etching of (1), it is possible to pattern the first film region at the same time when etching the main material, and it is possible to simplify the manufacturing process. There is also an effect that an easy and highly accurate aperture can be provided.

[Brief description of drawings]

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

FIG. 2 is a sectional view showing an aperture according to another embodiment of the present invention in the order of manufacturing steps.

FIG. 3 is a sectional view showing an aperture according to another embodiment of the present invention in the order of manufacturing steps.

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

FIG. 5 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 etching liquid 5 Aperture blank 6 Resist 7 Resist pattern 8 Metal film 8a Metal film pattern 9 Aperture of the present invention 10 Si oxide film 11 Upper Si plate 12 Lower Si plate

Claims (6)

[Claims] 1. A first film region used in an exposure method using a charged beam and having an opening, and a second film region supporting the first film region and thicker than the first film region. In the aperture having, the aperture is characterized in that the first film region is provided with at least one layer made of a substance having a conductivity higher than that of a main material forming the aperture. 2. The aperture according to claim 1, wherein the layer made of a substance having a conductivity higher than that of the main material is a material that is not etched when the main material is etched. 3. The first film region is composed only of a layer made of a substance having a conductivity higher than that of the main material, and the second film region is composed of only the main material. The aperture according to Item 1. 4. The aperture according to claim 1, wherein the second film region is made of Si single crystal. 5. The aperture according to claim 1, wherein the main material is Si single crystal. 6. The substance having a higher conductivity than the main material is Cu, Pt, Ag, W, Mo, Fe, Cr, Pd,
The aperture according to any one of claims 1 to 3, which is at least one selected from Ti, Nb, In, Sn, or a compound containing them as one component.