JP2006018097A - Fine grid manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fine grid manufacturing method where the surface of a base material is not oxidized even when a metal pattern film is formed on the base material, and consequently, etching processing is not affected. <P>SOLUTION: The fine grid manufacturing method for forming the fine grid 12 by etching the surface of the base material 10, comprises processes of: depositing a thin film on the surface of the base material 10 and forming a protective film 20; depositing a metal film 30a on the protective film 20, anodic-oxidizing the metal film 30a and forming the pattern film 30 having a hole pattern constituted of many fine holes 31 corresponding to the fine grid 12; etching the protective film 20 exposed through the fine holes 31 and making the fine holes 31 to reach the base material 10; and etching the base material 10 exposed through the fine holes 31 and forming the fine grid 12. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a fine lattice on a substrate, and more particularly to a method for producing a fine lattice on a substrate by etching.

  At present, optical members such as lenses and diffraction gratings are generally manufactured by electroforming a model material of the optical member to produce a mold, and manufacturing by injection molding using this mold. ing.

  Here, in order to prevent reflection of light, an antireflection grating having a grating interval (period) of half or less of the wavelength of incident light may be provided on the optical surface of the optical member. In order to form such an antireflective grating on the optical surface of the optical member, it is necessary to form a fine grating corresponding to the antireflective grating in the model material of the optical member for producing the mold as well. .

  As a method of forming such a fine lattice on the surface of the substrate, there is a method of forming the substrate by etching the substrate. Here, in order to etch the substrate, it is necessary to form an etching mask on the surface of the substrate. As a method of forming this etching mask, for example, as described in Patent Document 1, there is a method of forming an etching mask using a metal film.

In order to form a fine lattice by etching as described above, a metal film such as an aluminum film is first formed on a base material, and a pattern composed of fine holes corresponding to the fine lattice is formed on the metal film. Form. By etching the base material using the pattern film as an etching mask, the exposed portion of the base material is etched to form a large number of holes. Thereby, a fine lattice is formed.
Japanese Patent Laid-Open No. 10-096808

  By the way, an anodic oxidation method is used to form a pattern on the metal film. A conventional method for producing a fine lattice is shown in FIG. FIG. 2a shows the base material 100 before processing, and this base material 100 is made of silicon (Si). As shown in FIG. 2b, an aluminum film 105 is formed on the surface of the substrate 100. As shown in FIG. 2c, a large number of fine holes regularly arranged by anodization are formed in the aluminum film 105. Then, the pattern film 110 is formed.

  At this time, the exposed surface of the substrate 100 is also oxidized, and a silicon dioxide (SiO 2) film 130 is formed. Thus, when the surface of the base material 100 is oxidized, the etching state during the etching process changes. This is because silicon dioxide has a characteristic that it is less likely to be etched in the width direction than silicon.

  As shown in FIG. 2D, when the etching process is performed in a state where the surface of the base material 100 is oxidized, the oxidized film 130 of the base material 100 is silicon dioxide, and thus is etched in the thickness direction. When the etching is further advanced, as shown in FIG. 2e, the silicon portion of the substrate 100 is reached and etched in the width direction in addition to the thickness direction. When the etching process is finished, as shown in FIG. 2f, the pattern film 110 is removed to complete the fine lattice.

  As a result, the hole 120 to be formed has a shape having a reversely-inclined reverse inclined portion as shown in FIG. When the hole 120 has such a reverse inclined portion, when the die is formed by electroforming the base material 100, an undercut portion in which the reverse inclined portion is inverted is formed in the die. . When injection molding is performed using this mold, the material of the optical member is also filled in the undercut portion, so that it becomes difficult to release the mold. Therefore, it is desirable to have a shape that does not have an inversely inclined portion in the production of a fine lattice.

  The present invention has been made in view of the above problems, and even if a metal pattern film is formed on a substrate, the surface of the substrate is not oxidized and does not affect the etching process. The purpose is to provide.

In order to solve the above problems, a method for producing a fine lattice according to the present invention is a method for producing a fine lattice by etching a surface of a substrate.
Forming a thin film on the surface of the substrate to form a protective film;
Forming a metal film on the protective film, anodizing the metal film to form a pattern film having a hole pattern composed of a large number of micropores corresponding to the fine lattice;
Etching and etching the protective film exposed by the micropores, allowing the micropores to reach the substrate; and
And a step of etching and etching the base material exposed by the fine holes to form the fine lattice.

  The method for producing a fine lattice according to the present invention is characterized in that the protective film is formed of an oxide.

  The method for producing a fine lattice according to the present invention is characterized in that the protective film is formed of silicon dioxide.

  In addition, the fine lattice manufacturing method according to the present invention is characterized in that the pattern film is formed of aluminum.

  According to the method for producing a fine lattice according to the present invention, a thin film is formed on the surface of a substrate to form a protective film, a pattern film is formed on the protective film, etching is performed, and etching is performed. The substrate is covered with a protective film when anodizing the metal film by etching and forming a fine lattice after reaching the substrate, so that the substrate surface is not oxidized. Therefore, the reverse inclined portion is not formed on the upper portion of the hole formed in the base material.

  In addition, according to the method for producing a fine lattice according to the present invention, since the protective film is formed of an oxide, the protective film is already oxidized, so that it is not oxidized by anodization and the composition does not change. The material can be protected.

  Further, according to the method for producing a fine lattice according to the present invention, since the protective film is formed of silicon dioxide, the silicon dioxide has a characteristic that it is easily etched in the thickness direction and difficult to be etched in the width direction. Can be made to reach the surface of the base material with substantially the same width, and an etching mask having a mask pattern made of fine holes with a desired width can be easily formed.

  Further, according to the method for producing a fine lattice according to the present invention, since the pattern film is formed of aluminum, the formation of the fine holes is facilitated, and the size of the fine holes, the arrangement interval, etc. can be easily controlled. It becomes possible to form a hole pattern composed of a large number of fine holes corresponding to the fine lattice.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a process of forming an antireflection grid on a model material 10 according to an embodiment of the present invention. The model material 10 is made of silicon and is used to form a mold for injection molding of an optical member (FIG. 1a). The mold is formed by electroforming the model material 10.

  In the step of forming the antireflection grating 12 on such a model material 10, first, a protective film 20 made of silicon dioxide is formed on the surface of the model material 10 by sputtering, CVD, or the like (FIG. 1b). The protective film 20 plays a role of protecting the model material 10 from the electrolyte when anodizing.

  Next, an aluminum film 30a is formed on the protective film 20 (FIG. 1c). Then, the pattern material 30 is formed by immersing the model material 10 in the acidic electrolytic solution together with the aluminum film 30a and anodizing the aluminum film 30a. That is, the electrolytic solution is electrolyzed using the aluminum film 30a as an anode.

  When the aluminum film 30a is anodized in an acidic electrolytic solution, an oxide film is first formed on the surface of the aluminum film 30a, and a highly ordered array of recesses is formed on the surface of the oxide film by the action of acid. When the electrolysis is further continued, the formation of the recesses is promoted to erode the aluminum film 30a, and finally, the regularly arranged microscopic holes 31 and 31 are formed in the aluminum film 30a. Form.

  Since the size and arrangement interval of the fine holes 31 and 31 can be controlled by changing the applied voltage, the type of electrolyte, the concentration, and the like, here, the antireflection is achieved by anodizing the aluminum film 30a. A pattern film 30 having a hole pattern composed of micro holes 31 and 31 corresponding to the lattice 12 is formed (FIG. 1d). Here, since the surface of the model material 10 is covered by the protective film 20 made of silicon dioxide, the characteristics are not changed by being oxidized when the aluminum film 30a is anodized.

  Next, using the pattern film 30 as an etching mask, the model material 10 whose surface is covered with the protective film 20 is dry-etched with an etching gas (FIG. 1e). Thereby, first, the protective film 20 exposed from the aluminum film 30a of the model material 10 is etched.

  Since the protective film 20 made of silicon dioxide has a characteristic of being easily etched in the thickness direction and difficult to be etched in the width direction, the second mask film 50 is etched substantially uniformly in the thickness direction. As a result, the fine holes reach the surface of the model material 10 with substantially the same width.

  Etching is continued after the fine holes reach the surface of the model material 10 (FIG. 1f). Since silicon is easily etched in the width direction as well as in the thickness direction, when the etching on the model material 10 proceeds, an inclined surface 11 that gradually becomes narrower in the thickness direction is formed, and the spindle-shaped microhole 31 is formed. Form. Many of these are formed on the surface of the model material 10 to form the antireflection grating 12. Finally, the protective film 20 and the pattern film 30 are removed using a hydrofluoric acid treatment apparatus (FIG. 1g).

  Since the protective film 20 is formed on the surface of the model material 10 before forming the aluminum film 30a, the protective film 20 is formed on both the lower part of the exposed part of the model material 10 and the lower part of the unexposed part. Therefore, when the protective film 20 is etched by etching, the protective film 20 is prevented from being etched in the width direction, and a desired shape can be formed without forming a reverse inclined portion when the fine hole 31 is formed. Can be obtained.

  Therefore, when the mold is formed by subjecting the model material 10 to electroforming, a mold having no undercut portion can be obtained. When injection molding is performed using this mold, since there is no undercut part, it is easy to release and the manufacture of the optical member can be facilitated.

  The embodiment of the present invention has been described above. In the said embodiment, the case where the reflection preventing grid was formed in the surface of the model material of an optical member was mentioned as an example, and was demonstrated. However, in addition to this, the present invention can be widely applied when a fine lattice is formed on a substrate.

It is a figure which shows the process of forming an antireflection grating in the model material in the embodiment of the present invention. It is a figure which shows the process of forming an antireflection grating in the model material in the past.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Model material 11 Inclined surface 12 Antireflection grating 20 Protective film 30 Pattern film 30a Aluminum film 31 Micropore

Claims (4)

In the fine lattice manufacturing method of forming a fine lattice by etching on the surface of the substrate,
Forming a thin film on the surface of the substrate to form a protective film;
Forming a metal film on the protective film, anodizing the metal film to form a pattern film having a hole pattern composed of a large number of micropores corresponding to the fine lattice;
Etching and etching the protective film exposed by the micropores, allowing the micropores to reach the substrate; and
And a step of etching and etching the base material exposed by the fine holes to form the fine lattice.   2. The method for producing a fine lattice according to claim 1, wherein the protective film is formed of an oxide.   3. The method for producing a fine lattice according to claim 2, wherein the protective film is made of silicon dioxide.   The method for producing a fine lattice according to claim 1, wherein the pattern film is formed of aluminum.

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