JP2005327788A - Mold for forming fine pattern and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly productive fine pattern forming mold that can be used for forming a highly accurate fine pattern on a semiconductor surface and a method for manufacturing the same.
In a mold for forming a fine pattern in which irregularities 11d and 11e are formed on the surface of a mold 11c in order to transfer a fine pattern to the surface of a semiconductor substrate, the mold body on which the irregularities 11d and 11e are formed is formed of quartz glass. A mold 7 for forming a fine pattern, in which a thin film 15a having a photocatalytic action is formed on the surface of the mold 11c on the unevenness 11d, 11e side, and a manufacturing method thereof.
[Selection] Figure 2

Description

  The present invention relates to formation of a fine pattern of an integrated circuit using reactive ion etching, and more particularly to a mold for forming a fine pattern used in a nanoimprint method and a manufacturing method thereof.

  Conventionally, formation of a fine pattern on a semiconductor surface is important in forming a semiconductor element (device) using a quantum effect (see, for example, Patent Documents 1 and 2).

  The pattern dimension developed by the quantum effect is in the range of several nm to several tens of nm. Since this dimensional range is a value similar to the wavelength of light, it is difficult to accurately perform processing in this dimensional range using photolithography. Therefore, EB lithography that exposes a resist film with an electron beam is used as a method for substituting photolithography for fine processing in this dimension range.

  This method using EB lithography has a problem of low throughput.

  Therefore, a nanoimprint method is also used as an alternative to photolithography and EB lithography (see, for example, Non-Patent Document 1).

In this nanoimprint method, a SiO ₂ mold (mold) with a concavo-convex pattern formed on it is pressed against a resist that has been applied to the semiconductor surface in advance. This is a method of forming a fine pattern by processing by reactive ion etching (RIE).

  FIG. 4 is a sectional view showing steps 1 to 6 of conventional fine pattern formation using this method.

FIG. 4A shows a mold 27 prepared in advance. This mold 27 is a mold for forming a fine pattern made of SiO ₂ having a pattern of convex portions 27a formed on the surface (step 1).

  Next, as shown in FIG. 4B, a resist is applied to the surface of the semiconductor substrate 21 to be processed to form a resist film 28 (step 2).

As shown in FIG. 4C, the convex portion 27a of the SiO ₂ mold 27 is pressed against the resist film 28 formed by coating on the surface of the semiconductor substrate 21. The convex portion 27a of the mold 27 is pressed against the semiconductor substrate 21 with a pressure of about 1.3 × 10 ⁻⁷ Pa, and the fine pattern of the convex portion 27a is transferred to the resist film 28 (step 3).

  FIG. 4D shows a state of the semiconductor substrate 21 in which the pattern of the convex portions 27 a is transferred to the resist film 28 and the indentation 29 is formed on the resist film 28.

  The resist film 28 disappears in the portion where the convex portion 27a of the mold 27 is pressed, and an indentation 29 is formed. The resist film 28 remains in the portion where the convex portion 27a of the mold 27 is not pressed (step 4).

  FIG. 4E is a diagram showing a state in which reactive ion etching processing in which oxygen is introduced is performed on the surface of the semiconductor substrate 21 on which the indentation 29 is formed in the above-described step 4. This etching process is performed on the side of the semiconductor substrate 21 where the resist film 28 is formed. In the portion masked by the resist film 28, the semiconductor substrate 21 is not etched, and the portion masked by the resist film 28 remains as a convex portion. By this reactive ion etching process, a fine concave pattern 30 is obtained on the surface of the semiconductor substrate 21 (step 5).

  FIG. 4F shows the semiconductor substrate 20 from which the masked resist film 28 has been removed after the etching process is completed (step 6).

  In order to remove the resist film 28, the resist film 28 is irradiated with UV, and the resist film 28 is oxidized and decomposed. Oxidized and decomposed substances are exhausted.

  Thus, the semiconductor substrate 20 in which the fine concave pattern 30 is formed on the surface of the semiconductor substrate 21 is obtained through the steps 1 to 6.

  The mold used for the processing shown in FIG. 4 (a) is a mold 27 having a square or cylindrical convex portion 27a as shown in FIG. 5 (a), or a cone as shown in FIG. 5 (b). A mold 37 having a convex portion 37a is a known example.

  The prior art document information related to the invention of this application includes the following.

Japanese Patent Laid-Open No. 11-40548 JP 2000-91555 A S.Y.Chou, et.all., Science, vol.272, p85-87,5April, 1996

However, these molds 27, 37 are pressed against the resist film 28 with a pressure of about 1.3 × 10 ⁻⁷ Pa, so that the surfaces of the molds 27, 37, particularly the convex portions 27 a, 37 a contacting the resist film 28 are resisted. Adheres.

  When the resist adheres to the convex portions 27a and 37a, it is necessary to remove the adhered resist by washing in order to ensure the dimensional accuracy of the fine concave pattern 30 (see FIG. 4) to be formed. This cleaning generally requires the following steps.

  (1) The molds 27 and 37 mounted from a fine pattern forming apparatus (not shown) are removed.

  (2) The molds 27 and 37 are washed with an organic solvent or the like.

  (3) The washed molds 27 and 37 are dried.

  (4) The molds 27 and 37 are mounted again on the fine pattern forming apparatus.

  For this reason, there is a problem that time loss due to the cleaning of the molds 27 and 37 is large, which hinders improvement in throughput of semiconductor manufacturing.

  Accordingly, an object of the present invention is to provide a mold for forming a fine pattern with high productivity that can be used for forming a fine pattern with high precision on a semiconductor surface and a method for manufacturing the same.

  The present invention was devised to achieve the above object, and the first invention is a fine pattern forming mold in which irregularities are formed on the surface of a mold body to transfer a fine pattern to the surface of a semiconductor substrate. This is a mold for forming a fine pattern in which a mold body on which irregularities are formed is formed of quartz glass, and a thin film having a photocatalytic action is formed on the mold surface on the irregularities side.

In the second invention, the thin film is made of TiO ₂ .

In a third invention, the thin film is made of SiO ₂ doped with TiO ₂ .

  According to a fourth aspect of the present invention, there is provided a method for manufacturing a mold for forming a fine pattern in which irregularities are formed on the surface of a mold body so as to transfer a fine pattern to the surface of a semiconductor substrate. This is a method for producing a mold for forming a fine pattern, in which a thin film having a photocatalytic action is formed on the mold surface on the uneven side.

  A fifth invention is a manufacturing method in which the thin film is formed by a forming method such as a plasma CVD method, an EB vapor deposition method, or a coating method.

A sixth invention is a manufacturing method using a material in which the thin film is made of SiO ₂ doped with TiO ₂ or TiO ₂ .

  ADVANTAGE OF THE INVENTION According to this invention, the mold for fine pattern formation with high productivity which can be used in order to form a highly accurate fine pattern in the semiconductor surface, and its manufacturing method can be obtained.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings.

  FIG. 1A is a cross-sectional view showing a fine pattern forming mold 7 having a cylindrical or rectangular convex portion 55 formed according to the present embodiment.

As shown in the drawing, the fine pattern forming mold 7 has a TiO ₂ thin film 15a or TiO ₂ formed on the surface of the mold on the concave and convex side of the mold 11c in which a concave and convex pattern is formed on the surface of the mold body made of quartz glass. A thin film made of doped SiO ₂ is provided.

  In the fine pattern forming mold 7, the thin film 15 a is formed on the surface of the concave portion 54 and the convex portion 55 provided in the mold 11 c. The convex portion 55 provided with the thin film 15a is a fine convex pattern 56 for forming a fine pattern on the surface of the semiconductor substrate.

  The fine pattern forming mold 7 is a fine concave pattern 30 on the surface of the semiconductor substrate 21 shown in FIG. 4, instead of the conventional fine pattern forming mold 27 (see FIGS. 4A and 5A). It can be used for forming.

  That is, the mold 7 for forming a fine pattern has the same fine convex pattern 56 as the convex part 27 a of the mold 27. Therefore, when the fine pattern forming mold 7 is pressed against the semiconductor substrate 21 shown in step 3 of FIG. 4C, a fine pattern similar to the conventional one can be transferred to the resist film 28 of the semiconductor substrate 21. it can.

  FIG. 1B is a cross-sectional view showing a fine pattern forming mold 17 having a conical convex portion formed according to the present embodiment.

Forming a fine pattern mold 17, the uneven side of the mold surface of the mold 11m irregularities shaped pattern is formed on the surface of the mold body which is formed of quartz glass, SiO ₂ doped with thin 15a or TiO ₂ of TiO ₂ The thin film which consists of is provided.

  In the fine pattern forming mold 17, a thin film 15 a is formed on the surface of the concave and convex portions 65 provided in the mold 11 m. The convex portion 65 provided with the thin film 15a is a fine convex pattern 66 for forming a fine pattern on the surface of the semiconductor substrate.

  The fine pattern forming mold 17 can be used for forming a fine concave pattern on the surface of the semiconductor substrate, instead of the conventional fine pattern forming mold 37 (see FIG. 5B).

  That is, the fine pattern forming mold 17 has a fine convex pattern 66 similar to the convex portion 37a of the mold 37 shown in FIG. Therefore, when the fine pattern forming mold 17 is pressed against the semiconductor substrate 21 shown in step 3 of FIG. 4C, the fine convex pattern 66 is transferred to the resist film 28 on the semiconductor substrate 21 as in the prior art. can do.

  As described above, the fine pattern forming molds 7 and 17 are formed by forming irregularities on the surfaces of the molds 11c and 11m in order to transfer the fine pattern onto the surface of the semiconductor substrate.

  The fine pattern forming molds 7 and 17 have a structure in which the mold body of the molds 11c and 11m provided with unevenness is formed of quartz glass, and a thin film 15a having a photocatalytic action is formed on the surfaces of the molds 11c and 11m on the unevenness side. It has become.

  The concave / convex shapes of the fine pattern forming molds 7 and 17 are formed corresponding to the fine patterns formed on the surface of the semiconductor substrate, and are limited to the shapes shown in FIGS. 5 (a) and 5 (b). It is not a thing.

  FIG. 2 shows a process of manufacturing a mold for forming a fine pattern showing a preferred embodiment of the present invention shown in FIG.

  As shown in the figure, mold formation is performed sequentially by steps 1-5.

  As shown in FIG. 2A, a resist solution is applied to the surface of the quartz glass substrate 11 to form a resist film 12 for processing the quartz glass substrate. The quartz glass substrate 11 is a member for forming a mold body. The resist film 12 is a resist layer provided for forming a pattern by EB lithography (step 1).

  Next, a resist pattern is formed on the surface of the upper resist film 12.

  As shown in FIG. 2B, the resist film 12 formed on the surface of the quartz glass substrate 11 is subjected to pattern exposure with an electron beam by EB lithography. The exposed resist film is oxidized and decomposed by exposure, and the exposed resist film 12 is removed.

  In this way, a resist pattern for processing the quartz glass substrate patterned on the resist film 12 is formed by electron beam exposure (step 2).

  Reactive ion etching is performed as shown in FIG. 2C by an RIE apparatus (not shown) using the resist film 12 having a resist pattern formed on the surface of the quartz glass substrate 11 as a mask.

  When reactive ion etching is performed with the resist pattern formed on the resist film 12, the quartz glass in the portion without the resist film 12 is eroded by etching, and the concave pattern 11d is formed.

  When reactive ion etching is performed by the resist pattern formed by the resist film 12, a portion where the resist film 12 is present remains, and the remaining portion is formed on the semiconductor substrate 11 with a substantially cylindrical or square convex portion 11e (FIG. 2). (See (d)) is formed (step 3).

  Here, when forming the conical convex portion 65 of the fine pattern forming mold 17 as shown in FIG. 1B, the following process is further added during the reactive ion etching process. Perform in step 3.

  When the reactive ion etching process is performed, the quartz glass substrate 11 is cooled, so that the reaction product of the etching gas used during the etching adheres to the etched side surface of the quartz glass substrate 11. The reaction product adhering to the side surface acts as a protective film, and when the reactive ion etching proceeds with the reaction product adhering in this way, the etched surface is inclined as shown in FIG. A portion 65 is formed, and the convex portion 65 has a conical shape.

  The mold formed by etching in this way is in the shape of a mold 11m having a convex portion 65 that becomes the main body of the mold 17 for forming a fine pattern shown in FIG. 1B (step 3).

  FIG. 2D shows a state in which the resist film 12 has been removed from the quartz glass substrate 11 that has been subjected to reactive ion etching.

  By removing the resist film 12 on the surface of the quartz glass substrate 11 on which the concave pattern 11d is formed, a quartz glass mold 11c having a substantially cylindrical or square convex portion 11e formed on the quartz glass substrate 11 is obtained. Is obtained.

  The removal of the resist film 12 is performed by oxidizing and decomposing the resist film 12 by performing UV irradiation, and exhausting the material after the oxidation and decomposition.

  In the mold 11c, a recess pattern 11d having a depth of about 100 nm is formed in a portion not masked by the resist film 12. In other words, the quartz glass substrate 11 has the shape of the mold 11c which is the main body of the mold for forming a fine pattern by forming the concave pattern 11d and the convex part 11e (step 4).

  In the reactive ion etching process performed here, the depth of the recess pattern 11d is preferably in the range of about 20 to 300 nm.

  In consideration of the application conditions of the mold to be formed, the depth of the concave pattern 11d may be appropriately set so that the fine pattern is formed with high accuracy and sufficient strength of the mold 11c is obtained.

As shown in FIG. 1E, for example, a TiO ₂ thin film 15a is formed to a thickness of about 10 nm on the surface of the mold 11c on which the convex portions 11e and the concave pattern 11d are provided by a plasma CVD method (step 5).

In the formation of the thin film 15a by the plasma CVD method performed here, the film thickness of the TiO ₂ thin film 15a is in the range of about 5 to 20 nm, taking into account the application conditions of the mold to be formed, a highly accurate pattern and sufficient photocatalytic action. It is advisable to set the film thickness appropriately so as to obtain the above.

The TiO ₂ thin film 15a is a thin film having photocatalytic action by TiO ₂ . Due to this photocatalytic action, when UV irradiation is performed with the resist attached to the convex portion 11e, the resist attached to the surface of the convex portion 11e is oxidized and decomposed.

Instead of forming the TiO ₂ thin film 15a, a SiO ₂ thin film doped with TiO ₂ may be formed by plasma CVD. Also the TiO ₂ in the thin film of doped SiO _2, similar photocatalytic effects as the TiO ₂ thin film 15a is obtained.

Further, the thin film 15a may be formed by EB deposition in addition to the plasma CVD method, or by applying SiO ₂ doped with TiO ₂ or TiO ₂ to the surface of the mold 11c. The photocatalytic effect similar to that of the thin film 15a formed by the plasma CVD method is also obtained by the thin film 15a formed by the EB vapor deposition method and the coating method.

Through the above steps, the fine pattern forming mold 7 in which a thin film made of SiO ₂ is provided doped thin film 15a or TiO ₂ of the TiO ₂ is formed on the surface of the mold 11c. The fine pattern forming mold 7 corresponds to the pattern forming mold 27 shown in FIG.

  The operation of this fine pattern forming mold 7 obtained in steps 1 to 6 shown in FIG. 2 will be described with reference to FIGS.

Since the fine pattern forming mold 7 is provided with the TiO ₂ thin film 15a (or a thin film made of SiO ₂ doped with TiO ₂ ) on the uneven surface formed as already described with reference to FIG. 15a has a photocatalytic action.

  The fine pattern forming mold 7 is pressed against the resist film 28 of the semiconductor substrate 21 in the same manner as the mold 27 in step 3 of FIG. 4C, so that the fine convex pattern of the fine pattern forming mold 7 is formed on the surface of the resist film 28. 56 is transferred.

  At this time, a part of the resist film 28 adheres as a resist 16 as shown in FIG. 3A to the tip of the partial convex pattern 56 where the fine pattern forming mold 7 is in contact with the resist film 28.

  Even after the fine pattern forming mold 7 is separated from the resist film 28, most of the resist 16 attached to the fine convex pattern 56 of the fine pattern forming mold 7 remains attached.

  FIG. 3B is a diagram illustrating a state in which UV irradiation is performed on the fine pattern forming mold 7 to which the resist 16 is attached.

  The illustrated ultraviolet ray 19 is an ultraviolet ray generation source for irradiating the surface of the fine pattern forming mold 7 with UV, and is attached to an apparatus (not shown) for forming a fine pattern on the semiconductor substrate 21. Good.

  The ultraviolet ray 19 is preferably mounted at a position where UV irradiation is performed without shadow on the uneven surface of the fine pattern forming mold 7, particularly the fine convex pattern 56 in contact with the resist film 28. However, it is preferable to provide a uniform UV irradiation, not limited to the position of the projections and depressions provided in the fine pattern forming mold 7.

  By irradiating the fine pattern forming mold 7 with UV using an ultraviolet ray 19, the resist 16 attached by the photocatalytic action of the thin film 15a is oxidized and decomposed. The oxidized and decomposed material is exhausted from a device that forms a fine pattern (not shown).

  In this way, the resist 16 attached as shown in FIG. 3C is removed from the surface of the fine pattern forming mold 7.

  In the present embodiment, the removal of the resist 16 attached to the fine pattern forming mold 7 can be processed by performing UV irradiation without washing with an organic solvent or the like as in the prior art.

  For this reason, even if the resist 16 adheres by pressing the fine pattern forming mold 7 on the semiconductor surface, the resist 16 attached by UV irradiation can be decomposed and removed. For this reason, the clear fine convex pattern 56 can be maintained, and a reproducible fine pattern with high dimensional accuracy can be obtained in the semiconductor substrate 21 shown in FIG.

  Further, according to this embodiment, the resist 16 can be removed by providing an ultraviolet ray 19 for UV irradiation in an apparatus for forming a fine pattern. For this reason, it is not necessary to remove the mold 7 for forming a fine pattern from the apparatus for forming a fine pattern each time the resist 16 is removed as in the prior art.

  As described above, since the mold 7 for forming a fine pattern according to the present embodiment does not need to be detached from the apparatus, attached, dried, etc., in a semiconductor manufacturing process for forming a fine pattern on a semiconductor surface, a large throughput can be obtained. Improvement can be realized.

  In the case where a fine pattern is transferred and formed on the semiconductor surface using the fine pattern forming mold 17 instead of the fine pattern forming mold 7 as described above, the same as the fine pattern forming mold 7 described above. The following effects can be obtained.

  By applying the fine pattern formed by the fine pattern forming mold of the present invention to various circuits, it has industrial applicability that can realize an electromagnetic circuit, an optical waveguide, and the like.

Fig.1 (a) is sectional drawing which shows the mold for fine pattern formation which has the column-shaped or square-shaped convex part formed by this Embodiment. FIG.1 (b) is sectional drawing which shows the mold for fine pattern formation which has the cone-shaped convex part formed by this Embodiment. It is process drawing which shows process 1-5 of manufacture of the mold for fine pattern formation by this Embodiment. FIG. 3A is a cross-sectional view showing a state in which a resist is attached to the fine pattern forming mold of the present embodiment. FIG. 3B is a diagram showing a state in which UV irradiation is performed on the mold for forming a fine pattern. FIG. 3C is a cross-sectional view showing a state in which the resist attached by UV irradiation is decomposed. It is process drawing which shows the processes 1-6 which form a pattern in the semiconductor substrate surface using the conventional mold. Fig.5 (a) is sectional drawing which shows the mold which has the conventional cylindrical or square-shaped convex part. FIG.5 (b) is sectional drawing which shows the mold which has the conventional cone-shaped convex part.

Explanation of symbols

7 Mold for forming fine pattern 11 Quartz glass substrate 11c Mold 11d Recess pattern 11e Protrusion 11m Mold 12 Resist film 15a Thin film 17 Mold for forming fine pattern 54 Recess 55 Protrusion 56 Fine convex pattern 65 Protrusion 66 Fine convex pattern

Claims (6)

  In a mold for forming a fine pattern in which irregularities are formed on the surface of a mold body to transfer a fine pattern to the surface of a semiconductor substrate, the mold body on which the irregularities are formed is formed of quartz glass, and a photocatalyst is formed on the mold surface on the irregularity side. A mold for forming a fine pattern, wherein a thin film having an action is formed. Said thin film, forming a fine pattern mold according to claim 1, wherein comprising a TiO _2. Said thin film, forming a fine pattern mold according to claim 1, wherein composed of SiO ₂ doped with TiO _2.   In a method for manufacturing a mold for forming a fine pattern in which irregularities are formed on the surface of a mold body to transfer a fine pattern to the surface of a semiconductor substrate, the mold body on which the irregularities are formed is formed of quartz glass, and the mold on the irregularity side is formed. A method for producing a mold for forming a fine pattern, comprising forming a thin film having a photocatalytic action on a surface.   The method for producing a mold for forming a fine pattern according to claim 4, wherein the thin film is formed by a forming method such as a plasma CVD method, an EB vapor deposition method, or a coating method. 6. The method for producing a mold for forming a fine pattern according to claim 4, wherein the thin film is made of a material made of SiO ₂ doped with TiO ₂ or TiO ₂ .

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