JP2011159824A - Method for forming resin pattern by nanoimprinting method and method for forming diffraction grating - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming a resin pattern by the nanoimprinting method that can reduce the height of burr, and the like. <P>SOLUTION: The method for forming a resin pattern includes a step S3-1 for preparing a mold 21 with a raised section 25 where a master pattern 25P is formed; a step S3-2 for changing wettability; a step S3-3 for forming a resinous portion 33 on a base substrate 19; a step S3-5 for pressing the mold 21 onto the resinous portion 33; a step S3-7 for transferring the master pattern 25P to the resinous portion 33, by making the resinous portion 33 cure; and a step S3-9 for forming the resin pattern 33P1 in the resinous portion 33 by isolating the mold 21 from the resinous portion 33. In step S3-2, wettability is increased for the resinous portion 33 on the upper surface 19u of the substrate 19, and/or the wettability is reduced for the resinous portion 33, on the side surface 25S of the raised section 25 of the mold 21. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a resin pattern forming method by a nanoimprint method and a diffraction grating forming method.

  The following Patent Document 1 and Non-Patent Document 1 describe a fine pattern forming method by a nanoimprint method. In the fine pattern forming method based on the nanoimprint method described in Patent Document 1 below, a mold made of a light transmissive material and provided with a position reference mark and a wafer on which a mark corresponding to the mark is formed are used. ing. Thus, it is described that the mold and the wafer can be aligned during patterning by the nanoimprint method.

  Non-Patent Document 1 below describes a microfabrication method using a nanoimprint transfer method called a step-and-repeat method. In this fine processing method, a mold having a flat plate-shaped mold base portion and a raised portion provided on the mold base portion and having a transfer master pattern formed on the upper surface is used. When pattern transfer is performed by this method, first, a resin portion made of a liquid ultraviolet curable resin is formed on a substrate to be processed. Then, the partial region of the resin part and the master pattern of the mold are opposed to each other, the master pattern is pressed against the partial region, the partial region is irradiated with light to cure the partial region, and the mold is separated from the optical resin layer. A series of steps are repeated in order for each partial region. Thereby, the master pattern of the mold is transferred to the resin part.

JP 2000-323461 A

M. Miller, et. Al., “Fabrication of Nanometer Sized Features on Non-Flat Substrate Using a Nano-Imprint Lithography Process”, Proc. SPIE 5751,994, pp.995-998, (2005)

  The fine processing by the nanoimprint method using the step-and-repeat method described above is used, for example, for forming a diffraction grating pattern of a distributed feedback semiconductor laser. In this step-and-repeat nanoimprint method, when the transfer pattern of the raised part of the mold is pressed against a partial region of the resin part made of ultraviolet curable resin, a part of the ultraviolet curable resin constituting the resin part becomes the mold and resin. It is pushed out of the contact area with the part. The extruded ultraviolet curable resin may form a “burr” from the upper surface of the substrate coated with the ultraviolet curable resin to the side surface of the raised portion of the mold. In the subsequent process, this burr is also cured by light irradiation. Since the burrs thus cured cause deterioration of the yield of a finished product (for example, a distributed feedback semiconductor laser), it is preferable to remove the burrs. Since the hardened burrs are difficult to remove by wet etching using an organic solvent, it is necessary to use a dry etching method such as oxygen plasma treatment.

  However, if the height of this burr is high, it takes time to remove the burr. Therefore, when the burr is removed, the area around the burr (for example, the diffraction grating layer of the distributed feedback semiconductor laser) may be damaged. is there. In order to reduce such damage, it is necessary to reduce the height of burrs formed when the master pattern of the mold is transferred to the resin portion.

  The present invention has been made in view of such problems, and provides a resin pattern forming method by a nanoimprint method capable of reducing the height of burrs, and a method of forming a diffraction grating using the resin pattern forming method. With the goal.

  In order to solve the above-described problems, a resin pattern forming method according to the present invention is a resin pattern forming method by a nanoimprint method, and is provided with a mold base part and a master pattern for nanoimprint that is provided on the mold base part and includes a concavo-convex pattern. A mold preparing step for preparing a mold having a raised portion formed on the upper surface, a wettability changing step for changing wettability, and a resin portion forming step for forming a resin portion made of an ultraviolet curable resin on the substrate, A pressing process for pressing the mold against the resin part, a curing process for transferring the master pattern to the resin part by irradiating the resin part with ultraviolet rays while the mold is pressed against the resin part, and a resin molding the mold A separation step of forming a resin pattern on the resin portion by separating the portion from the portion, and changing wettability. In the step, it increases the wettability to the resin portion of the upper surface of the substrate, and / or, wherein the reducing wettability to the resin portion of the side surface of the raised portion of the mold.

  In the resin pattern forming method according to the present invention, in the wettability changing step, the wettability with respect to the resin portion on the upper surface of the substrate is increased and / or the wettability with respect to the resin portion on the side surface of the raised portion of the mold is decreased.

  When the wettability with respect to the resin part on the upper surface of the substrate is increased, the protruding part of the resin part that is pushed out of the contact area between the master pattern of the mold and the resin part in the pressing process has a smaller contact angle. It contacts the upper surface of the substrate. Thereby, it is suppressed that the protrusion part reaches from the upper surface of a base | substrate to the side surface of the raised part of a mold. As a result, even if the protruding portion is hardened and becomes a burr, the burr can be prevented from reaching the side of the raised portion of the mold from the upper surface of the base, and hence the height of the burr is suppressed.

  In addition, when the wettability to the resin part on the side surface of the raised part of the mold is reduced, in the pressing process, the protruding part pushed out of the contact area between the mold master pattern and the resin part in the resin part is It can contact the side surface of the mold only when the contact angle with the side surface of the raised portion of the mold is large. As a result, the protruding portion is less likely to come into contact with the side surface of the raised portion of the mold, so that the protruding portion is prevented from reaching the side surface of the raised portion of the mold from the upper surface of the base. As a result, even if the protruding portion is hardened and becomes a burr, the burr can be prevented from reaching the side of the raised portion of the mold from the upper surface of the base, and hence the height of the burr is suppressed. As described above, according to the resin pattern forming method of the present invention, it is possible to reduce the height of burrs generated when the resin pattern is formed.

  Furthermore, in the resin pattern forming method according to the present invention, in the wettability changing step, the difference between the wettability with respect to the resin part on the upper surface of the substrate and the wettability with respect to the resin part on the side surface of the raised part of the mold is increased. It is preferable to increase the wettability with respect to the resin part on the upper surface of the substrate.

  The smaller the difference between the wettability with respect to the resin part on the upper surface of the substrate and the wettability with respect to the resin part on the side surface of the raised part of the mold, the contact area between the master pattern of the mold and the resin part in the pressing part. The protruding part pushed out to the outside of the substrate tends to come into contact with both the upper surface of the base and the side surface of the raised part of the mold, that is, the protruding part tends to reach from the upper surface of the base to the side of the raised part of the mold. . Therefore, by increasing the difference between the wettability with respect to the resin part on the upper surface of the substrate and the wettability with respect to the resin part on the side surface of the raised part of the mold in the wettability changing step, the height of burrs generated when forming the resin pattern is increased. It is possible to further reduce the thickness.

  Furthermore, in the resin pattern forming method according to the present invention, in the wettability changing step, it is preferable to increase the wettability of the upper surface of the substrate with respect to the resin portion by performing oxygen plasma treatment on the upper surface of the substrate. Thereby, the wettability with respect to the resin part of the upper surface of a base | substrate can be increased easily.

  Further, in the resin pattern forming method according to the present invention, in the wettability changing step, the difference between the wettability with respect to the resin part on the side surface of the raised part of the mold and the wettability with respect to the resin part on the upper surface of the base is increased. It is preferable to reduce the wettability of the side surface of the raised portion of the mold to the resin portion.

  The smaller the difference between the wettability with respect to the resin part on the side surface of the raised part of the mold and the wettability with respect to the resin part on the upper surface of the base, the contact area between the master pattern of the mold and the resin part in the pressing part The protruding part pushed out to the outside of the substrate tends to come into contact with both the upper surface of the base and the side surface of the raised part of the mold, that is, the protruding part tends to reach from the upper surface of the base to the side of the raised part of the mold. . Therefore, by increasing the difference between the wettability with respect to the resin portion on the side surface of the raised portion of the mold and the wettability with respect to the resin portion on the upper surface of the base in the wettability changing step, the height of burrs generated when forming the resin pattern is increased. It is possible to further reduce the thickness.

  Further, in the resin pattern forming method according to the present invention, in the wettability changing step, the side surface of the raised portion of the mold is coated with a coating material having lower wettability with respect to the resin portion than wettability with respect to the resin portion on the side surface. It is preferable to reduce wettability with respect to the resin portion on the side surface of the raised portion of the mold. Thereby, the wettability with respect to the resin part of the side surface of the raised part of a mold can be reduced easily.

  Further, in this case, the coating material is preferably a fluororesin. Thereby, the wettability with respect to the resin part of the side surface of the raised part of a mold can be reduced easily.

  Further, the method for forming a diffraction grating according to the present invention is a method for forming a diffraction grating by a nanoimprint method, and a substrate forming step of forming a substrate having a substrate body and an insulating layer provided on the substrate body. And a resin pattern forming step of forming a resin pattern on the resin portion on the substrate by any one of the resin pattern forming methods described above after the substrate forming step, and a resin portion formed on the silicon-containing resin layer after the resin pattern forming step. And using the silicon-containing resin layer as a mask after the resin pattern exposing step of exposing the convex portions of the resin pattern of the resin portion by etching a part of the silicon-containing resin layer and etching the part of the silicon-containing resin layer By etching the convex part of the resin pattern of the exposed resin part and forming a hole that penetrates the resin part and reaches the insulating layer, the resin pattern After the reverse concavo-convex pattern forming step for forming the reverse concavo-convex pattern, which is the concavo-convex reverse pattern, and the reverse concavo-convex pattern forming step, by etching the insulating layer using the silicon-containing resin layer and the resin portion as a mask, An insulating layer uneven pattern forming step for forming an insulating layer uneven pattern corresponding to the inverted uneven pattern of the resin portion on the insulating layer, and a removing step for removing the silicon-containing resin layer and the resin portion after the insulating layer uneven pattern forming step, After the insulating layer concavo-convex pattern forming step, the substrate main body portion is etched using the insulating layer as a mask to form a diffraction grating corresponding to the insulating layer concavo-convex pattern on the substrate main body portion, and UV curing The resin is a silicon-free resin, and the insulating layer is made of a material different from the material of the upper surface of the base body. In the resin pattern exposure step, the part of the silicon-containing resin layer is etched by an etching method in which the etching rate for the silicon-containing resin layer is higher than the etching rate for the resin portion. Etching the resin pattern protrusions of the resin part exposed by the etching method with a higher etching rate for the resin part than the etching rate, and in the insulating layer uneven pattern forming step, the etching rate for the material on the upper surface of the substrate body part The insulating layer is etched by an etching method having a higher etching rate with respect to the insulating layer.

  According to the method for forming a diffraction grating according to the present invention, since the resin pattern is formed by any one of the resin pattern forming methods described above, the height of burrs generated when the resin pattern is formed can be reduced. It becomes possible. As a result, it is possible to reduce defects caused by the presence of burrs when forming the diffraction grating.

  Furthermore, in the method for forming a diffraction grating according to the present invention, the diffraction grating is formed on the base body by etching the base body using the insulating layer on which the insulating layer uneven pattern is formed as a mask. Here, the formation of the concave / convex pattern of the insulating layer is performed by selectively etching the silicon-containing resin layer, the resin portion, and the insulating layer in order after forming the resin pattern on the resin portion in the resin pattern forming step. ing. Therefore, even if the flatness of the upper surface of the base body portion is poor and the thickness of the resin pattern of the resin portion varies due to the poor flatness, this variation is caused by the diffraction grating formed on the base body portion. The influence on the shape is reduced. In addition, the depth of the concave portion of the diffraction grating formed in the base body portion in the base body etching step can be accurately controlled by the etching time of the base body portion using the insulating layer as a mask.

  The diffraction grating forming method according to another aspect of the present invention is a method for forming a diffraction grating by a nanoimprint method, and a resin pattern is formed on a resin portion on a substrate by any one of the resin pattern forming methods described above. And a substrate etching step of forming a diffraction grating corresponding to the resin pattern on the substrate by etching the resin portion and the substrate after the resin pattern forming step.

  According to the diffraction grating forming method of another aspect of the present invention, since the resin pattern is formed by any of the above-described resin pattern forming methods, the height of burrs generated when forming the resin pattern is reduced. It can be reduced. As a result, it is possible to reduce defects caused by the presence of burrs when forming the diffraction grating.

  Further, in the above-described method for forming each diffraction grating according to the present invention, the base body may include a semiconductor material, and the diffraction grating formed in the base body etching step may be a diffraction grating of a distributed feedback semiconductor laser.

  ADVANTAGE OF THE INVENTION According to this invention, the resin pattern formation method by the nanoimprint method which can reduce the height of a burr | flash, and the formation method of a diffraction grating using the same are provided.

It is a flowchart which shows the formation method of the diffraction grating of 1st Embodiment. It is a flowchart which shows the resin pattern formation method of 1st Embodiment. FIG. 3A is a plan view of the base body portion for explaining the base body forming step. FIG. 3B is a view showing a cross section of the base body portion along the line IIIB-IIIB in FIG. It is a figure which shows the cross section of the base | substrate for demonstrating a base | substrate formation process. FIG. 5A is a diagram showing a cross section of a mold prepared in the mold preparation process. FIG. 5B is a plan view showing the mold prepared in the mold preparation process. FIG. 6A is a diagram showing a cross-section of the substrate and the like for explaining the wettability changing step. FIG. 6B is a diagram showing a cross section of the base body and the like for explaining the resin pattern forming step. FIG. 7A is a diagram illustrating a cross section of the base, the mold, and the like for explaining the pressing step. FIG. 7B is a diagram showing a cross section of the base, the mold, and the like for explaining the curing process. FIG. 8A is a diagram showing a cross section of the base and the mold for explaining the separation step. FIG. 8B is a diagram showing a cross section of the base body and the like for explaining the step of covering with the silicon-containing resin layer. FIG. 9A is a view showing a cross section of a base body and the like for explaining the resin pattern exposure step. FIG. 9B is a diagram showing a cross-section of the base body and the like for explaining the reverse concavo-convex pattern forming step. FIG. 10A is a diagram showing a cross-section of the base body and the like for explaining the insulating layer unevenness pattern forming step. FIG. 10B is a view showing a cross section of the base body portion and the like for explaining the removing step. FIG. 11A is a view showing a cross section of the base body portion and the like for explaining the base body etching step. FIG. 11B is a view showing a cross section of the base body portion for illustrating the step of removing the insulating layer. It is a fragmentary sectional perspective view of the distributed feedback type semiconductor laser manufactured using the resin pattern formation method by the nanoimprint method and diffraction grating formation method concerning a 1st embodiment. It is a figure which shows the cross section of the mold for demonstrating the wettability change process of 2nd Embodiment. It is a figure which shows the cross section of the base | substrate etc. for demonstrating the pressing process of 2nd Embodiment. It is a figure which shows the cross section of the base | substrate etc. for demonstrating a hardening process. It is a flowchart which shows the formation method of the diffraction grating of 3rd Embodiment. FIG. 17A is a view showing a cross section of the base body portion and the like for explaining the resin pattern forming step of the third embodiment. FIG. 17B is a view showing a cross section of a part of the substrate main body for illustrating the substrate etching process of the embodiment.

  Hereinafter, a resin pattern formation method and a diffraction grating formation method by a nanoimprint method according to an embodiment will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used for the same elements when possible. In addition, the dimensional ratios in the components in the drawings and between the components are arbitrary for easy viewing of the drawings.

(First embodiment)
First, a manufacturing method of a distributed feedback semiconductor laser using a resin pattern forming method by a nanoimprint method and a diffraction grating forming method according to the first embodiment will be described.

  FIG. 1 is a flowchart showing a method for forming a diffraction grating according to this embodiment, and FIG. 2 is a flowchart showing a resin pattern forming method according to this embodiment.

  As shown in FIG. 1, the method of forming a diffraction grating according to the present embodiment includes a base body forming step S1, a resin pattern forming step S3, a step S5 covered with a silicon-containing resin layer, a resin pattern exposing step S7, and an inversion unevenness. A pattern forming step S9, an insulating layer uneven pattern forming step S11, a removing step S13, and a substrate etching step S15 are provided. Here, the resin pattern forming method of the present embodiment corresponds to the resin pattern forming step S3. As shown in FIG. 2, the resin pattern forming step S3 includes a mold preparing step S3-1, a wettability changing step S3-2, a resin part forming step S3-3, a pressing step S3-5, and a curing step S3. -7, separation step S3-9, and determination step S3-11. Details of these steps will be described below.

(Substrate formation process)
3A is a plan view of the base body portion for explaining the base body forming step, and FIG. 3B is a cross-sectional view of the base body portion taken along the line IIIB-IIIB in FIG. FIG.

  In the substrate forming step S1, first, as shown in FIG. 3B, the first cladding layer 3, the first optical confinement layer 5, the active layer 7, the first layer are formed on the semiconductor substrate 1 by, eg, metal organic vapor phase epitaxy. The two-light confinement layer 9 and the semiconductor layer 11 are formed in this order. The semiconductor substrate 1, the first cladding layer 3, the first light confinement layer 5, the active layer 7, the second light confinement layer 9, and the semiconductor layer 11 form the base body 13. 3A and 3B, an orthogonal coordinate system 2 is shown, and the Z axis is set in the thickness direction of the semiconductor substrate 1, and the X axis and the Y axis are set in directions perpendicular thereto. is doing. The main surface and the back surface of the semiconductor substrate 1 are respectively parallel to the XY plane, and the stacking direction of the first cladding layer 3, the first light confinement layer 5, the active layer 7, the second light confinement layer 9, and the semiconductor layer 11 is , Along the Z axis. In addition, also in each figure after FIG. 3 (A) (B), the orthogonal coordinate system 2 is shown as needed.

  The semiconductor substrate 1 is a first conductivity type (for example, n-type) semiconductor substrate, and is made of, for example, a III-V group compound semiconductor such as InP or GaN. The first cladding layer 3 is made of a first conductivity type III-V group compound semiconductor such as InP or GaN. The first optical confinement layer 5 is made of a first conductivity type III-V group compound semiconductor such as GaInAsP. The active layer 7 has, for example, an MQW (multiple quantum well) structure or an SQW (single quantum well) structure. The active layer 7 is made of, for example, a III-V group compound semiconductor such as GaInAsP or AlGaInAs. The second optical confinement layer 9 is made of a III-V group compound semiconductor such as GaInAsP of the second conductivity type (p-type when the first conductivity type is n-type). The semiconductor layer 11 is made of a second conductivity type III-V group compound semiconductor such as GaInAsP. In the semiconductor layer 11, a diffraction grating 11P is formed in a later process (see FIG. 11A). The first light confinement layer 5 and the second light confinement layer 9 may not be formed.

  As shown in FIG. 3A, the semiconductor layer 11 has a plurality of virtual regions 11A. As will be described later, in the resin portion on the semiconductor layer 11, the master pattern of the mold is transferred in order by the nanoimprint method for each region on each virtual region 11A (that is, the resin pattern 33 is formed). When the semiconductor substrate 1 has a disk shape with a diameter of 2 inches, for example, the length in the X-axis direction and the length in the Y-axis direction of the virtual region 11A can be set to, for example, 10 mm and 10 mm, respectively.

  FIG. 4 is a view showing a cross section of a base for explaining the base formation step. After the base body portion 13 is formed as described above, the insulating layer 15 and the adhesion layer 17 are formed in this order on the base body portion 13 as shown in FIG. The insulating layer 15 can be formed by, for example, a plasma chemical vapor deposition method. The adhesion layer 17 can be formed by, for example, a spin coating method. In this way, the base 19 composed of the base body 13, the insulating layer 15, and the adhesion layer 17 is formed. Note that the adhesion layer 17 may not be formed. In this case, the base body portion 13 and the insulating layer 15 form the base body 19.

The insulating layer 15 is made of a material different from the material of the upper surface 13 u of the base body 13, that is, the material constituting the uppermost semiconductor layer 11 of the base body 13 in this embodiment. As a material constituting the insulating layer 15, for example, a silicon compound such as silicon oxide (SiO ₂ ), silicon nitride oxide (SiON), or silicon nitride (SiN) can be used. The thickness of the insulating layer 15 is preferably 30 nm or more and 50 nm or less. If the thickness of the insulating layer 15 is 30 nm or more, the width of the line portion 11M of the diffraction grating 11P is narrower than the width of the line portion 15M of the insulating layer 15 in the substrate etching step S15 as will be described later. It can be sufficiently suppressed (see FIGS. 10A and 11A). If the thickness of the insulating layer 15 is 50 nm or less, in the insulating layer uneven pattern forming step S11 described later, the insulating layer 15 is removed while the silicon-containing resin layer 37 remains, and the insulating layer uneven pattern 15P. Can be easily formed (see FIG. 10A).

  The adhesion layer 17 is a layer provided to improve adhesion between the insulating layer 15 and a resin portion 33 (see FIG. 6B) described later. As a material constituting the adhesion layer 17, for example, a novolac resin such as DUV40 manufactured by Brewer Science can be used. The thickness of the adhesion layer 17 is preferably 50 nm or more and 80 nm or less. If the thickness of the adhesion layer 17 is 50 nm or more, even if the surface flatness of the semiconductor substrate 1 is low, the surface flatness of the adhesion layer 17 can be sufficiently increased. Further, if the thickness of the adhesion layer 17 is 80 nm or less, the inversion concavo-convex pattern 33P2 is formed by removing the adhesion layer 17 while the silicon-containing resin layer 37 remains in a reverse concavo-convex pattern forming step S9 described later. (See FIG. 9B).

(Resin pattern forming process)
As described above, the resin pattern forming step S3 includes the mold preparing step S3-1, the wettability changing step S3-2, the resin part forming step S3-3, the pressing step S3-5, and the curing step S3-7. And a separation step S3-9 and a determination step S3-11.

(Mold preparation process)
FIG. 5A is a diagram showing a cross section of the mold prepared in the mold preparation process, and FIG. 5B is a plan view showing the mold prepared in the mold preparation process. In the mold preparation step S3-1, a mold used for pattern transfer by the nanoimprint method is prepared.

  As shown in FIGS. 5A and 5B, the mold 21 prepared in the mold preparation step S3-1 includes a rectangular flat plate-shaped mold base portion 23 extending along the XY plane, and a mold base portion. And a raised portion 25 that swells in the thickness direction of the mold base portion 23 (the direction along the Z axis). In the present embodiment, the mold base portion 23 and the raised portion 25 are integrally formed, but in FIG. 5A, for convenience, the boundary between them is indicated by a broken line.

  The upper surface of the raised portion 25, that is, the Z-axis negative side surface of the raised portion 25 is a pattern surface 25F extending along the XY plane. On the pattern surface 25F, there is formed a master pattern 25P for nanoimprint made of a concavo-convex pattern. A surface from the end portion of the pattern surface 25F to the mold base portion 23 is a side surface 25S of the raised portion 25.

  In the present embodiment, the master pattern 25P includes a plurality of line portions 25M that are convex portions protruding in a direction along the Z axis, and a plurality of space portions 25V that are concave portions recessed in a direction along the Z axis. The master pattern 25P is a line and space pattern in which the line portions 25M and the space portions 25V are alternately and periodically arranged in the direction along the X axis.

  The plurality of line portions 25M have substantially the same shape, and each extend in a direction along the Y axis. The cross section along the XZ plane of each line portion 25M is rectangular. The width L25M in the direction along the X axis of each line portion 25M is such that the width of the line portion 11M of the diffraction grating 11P corresponds to an oscillation wavelength generally used in an optical communication semiconductor laser, as will be described later. (See FIG. 11A), the thickness can be set to 100 nm to 150 nm. The plurality of space portions 25V have substantially the same shape, and each extend in a direction along the Y axis. The cross section along the XZ plane of each space portion 25V is rectangular. The width L25V in the direction along the X axis of each space portion 25V can be set to, for example, 70 nm to 150 nm. If the width L25V is 70 nm or more, the resin portion 33 cured in the master pattern 25P can be easily separated from the mold 21 in the later-described separation step S3-9 (see FIG. 8A). If the width L25V is 150 nm or less, as described later, the width of the space portion 11V of the diffraction grating 11P is set to a width corresponding to an oscillation wavelength generally used in an optical communication semiconductor laser. it can.

  In the present embodiment, the width L25M of the line portion 25M and the width L25V of the space portion 25V are substantially equal, and the height D25L of the line portion 25M along the Z axis is the height of the space portion 25V along the Z axis. Is almost equal. In order to keep the shape of the space portion 25V rectangular, the aspect ratio of the space portion 25V is preferably 2 or less. From this viewpoint, the height D25L can be set to 140 nm to 300 nm. The irregular pattern period λ25 in the direction along the X axis of the master pattern 25P (that is, the total value of the width L25M of one line portion 25M and the width L25V of one space portion 25V) is a diffraction grating as will be described later. The period λ11 of 11P can be set to 200 nm to 250 nm so as to be a period corresponding to an oscillation wavelength generally used in a semiconductor laser for optical communication. The length in the X-axis direction and the length in the Y-axis direction of the master pattern 25P can be set to, for example, 5 mm to 20 mm and 5 mm to 20 mm, respectively, in consideration of the flatness of the general semiconductor substrate 1.

  The height in the direction along the Z axis of the raised portion 25 (that is, the length from the pattern surface 25F to the mold base portion 23) can be, for example, 10 μm to 20 μm. The internal angle θ25 formed by the pattern surface 25F and the side surface 25S can be, for example, 60 degrees to 75 degrees.

  The mold base part 23 and the raised part 25 are made of a material such as quartz or silicone resin, for example. Quartz and silicone resin are preferable because they transmit ultraviolet rays 35 (see FIG. 7B) as described later.

(Wettability change process)
FIG. 6A is a diagram showing a cross-section of the substrate and the like for explaining the wettability changing step. In the wettability changing step S3-2 of the present embodiment, as shown in FIG. 6A, the wettability of the upper surface 19u of the base 19 with respect to a resin portion 33 (see FIG. 6B) described later is increased. Process. Specifically, for example, as shown in FIG. 6A, the wettability of the upper surface 19u of the base 19 with respect to the resin portion 33 is increased by surface-treating the upper surface 19u of the base 19 with the oxygen plasma 31. According to the surface treatment with the oxygen plasma 31, the wettability of the upper surface 19u of the base 19 with respect to the resin portion 33 can be easily increased. The increase in wettability in this case is considered to be caused by the formation of a hydroxyl group, which is a hydrophilic group, on the upper surface 19 u by the surface treatment with the oxygen plasma 31. In addition to the surface treatment with the oxygen plasma 31, wettability of the upper surface 19u of the substrate 19 with respect to the resin portion 33 can be increased by wet cleaning with a mixed solution of sulfuric acid and hydrogen peroxide or alkali treatment with ammonia. Thereafter, in order to facilitate the separation of the resin part 33 and the mold 21 in the separation step S3-9 described later, HMDS (hexamethyl gin lazan) may be coated on the upper surface 19u in a gas phase or a liquid phase (FIG. 8 (A)). Further, the same effect (an effect of easily separating the resin part 33 and the mold 21) can be obtained by adding fluorine to the resin part 33.

(Resin pattern forming process)
Resin pattern formation process S3 is performed after the above-mentioned wettability change process S3-2. FIG. 6B is a diagram showing a cross section of the base body and the like for explaining the resin pattern forming step. In the resin pattern forming step S3, as shown in FIG. 6B, a resin portion 33 made of an ultraviolet curable resin is formed on the upper surface 19u of the base body 19. The resin part 33 is in a state having fluidity such as liquid. Further, unlike the silicon-containing resin layer 37 (see FIG. 8B) described later, the resin portion 33 is an ultraviolet curable resin that does not substantially contain silicon. Here, if the silicon content rate of the resin part 33 is 0.1 atomic% or less, it can be considered that the resin part 33 does not contain silicon substantially. As the ultraviolet curable resin constituting the resin portion 33, for example, an acrylic resin or an epoxy resin can be used.

  In the present embodiment, the resin portion 33 is formed on the upper surface 19u of the base 19 on the surface above one virtual region 11A. The resin portion 33 can be formed by, for example, dropping a liquid ultraviolet curable resin onto the upper surface 19 u of the base 19. In the present embodiment, the resin part 33 is composed of a plurality of parts separated from each other, but the resin part 33 may be composed of one part.

(Pressing process)
A pressing step S3-5 is performed after the resin portion forming step S3-3. FIG. 7A is a diagram illustrating a cross section of the base, the mold, and the like for explaining the pressing step.

  In the pressing step S3-5, the pattern surface 25F of the mold 21 is opposed to the surface on one virtual region 11A in the upper surface 19u of the base body 19, and then, as shown in FIG. Is pressed against the resin portion 33. At this time, the upper surface 19u of the base 19 and the pattern surface 25F are made to be substantially parallel. The distance between the mold 21 and the base 19 when the pattern surface 25F is pressed against the resin portion 33, that is, the distance from the pattern surface 25F to the upper surface 19u is raised by excavation by wet etching of a plate-like substrate such as quartz. In consideration of a margin for side etching that occurs when the portion 25 is formed, the thickness can be set to, for example, 100 μm to 200 μm. A part of the resin portion 33 against which the pattern surface 25F is pressed is pushed out of the contact area between the master pattern 25P and the resin portion 33, and becomes a protruding portion 33b1.

  In the above-described wettability changing step S3-2, the wettability with respect to the resin portion 33 of the upper surface 19u of the base 19 is increased, so that the upper surface 19u is compared with the case where the wettability changing step S3-2 is not performed. The contact angle θ33 of the protruding portion 33b1 is small. Moreover, it is preferable that wettability change process S3-2 is performed so that contact angle (theta) 33 may be 5 degree | times or more and 10 degrees or less. This is because when the contact angle θ33 is 5 degrees or more, the width of the protruding portion 33b1 in the direction along the X axis can be sufficiently shortened, and the burr 33b2 (see FIG. 7B) to be formed later can be formed. This is because the width in the direction along the X axis can be made sufficiently short, and when the contact angle θ33 is 10 degrees or less, the height of the protruding portion 33b1 in the direction along the Z axis is sufficiently low. This is because the height in the direction along the Z-axis of the burr 33b2 to be formed later can be sufficiently reduced.

(Curing process)
A curing step S3-7 is performed after the pressing step S3-5. FIG. 7B is a diagram showing a cross section of the base, the mold, and the like for explaining the curing process.

  In the curing step S3-7, the resin portion 33 is cured by irradiating the resin portion 33 with ultraviolet rays while the pattern surface 25F is pressed against the resin portion 33. When the mold 21 is composed of a member that transmits ultraviolet rays, in the curing step S3-7, as shown in FIG. 7B, the ultraviolet rays 35 may be irradiated from above the mold 21 toward the resin portion 33. it can. The ultraviolet rays 35 pass through the mold 21 and reach the resin part 33 to cure the resin part 33. As a result, the protruding portion 33b1 is also cured and becomes a burr 33b2. In this manner, the resin pattern 33P1, which is a transfer pattern of the master pattern 25P, is fixed to the resin portion 33.

(Separation process)
After the curing step S3-7, a separation step S3-9 is performed. FIG. 8A is a diagram showing a cross section of the base and the mold for explaining the separation step.

  In the separation step S3-9, the mold 21 is separated from the resin portion 33 as shown in FIG. In this manner, the resin pattern 33P1 is formed in the resin portion 33. Since the resin pattern 33P1 is a transfer pattern of the master pattern 25P, in the present embodiment, the resin pattern 33P1 is a line and space pattern. Specifically, the resin pattern 33P1 includes a plurality of line portions 33M1 that are convex portions protruding in the direction along the Z axis, and a plurality of space portions 33V1 that are concave portions recessed in the direction along the Z axis. The resin pattern 33P1 is a line and space pattern in which the line portions 33M1 and the space portions 33V1 are alternately and periodically arranged in the direction along the X axis.

  Each line portion 33M1 has substantially the same shape, and extends in the direction along the Y axis. The cross section along the XZ plane of each line portion 33M1 is rectangular. The width in the direction along the X axis and the height in the direction along the Z axis of each line portion 33M1 are substantially equal to the width L25V and the height D25L of the space portion 25V of the master pattern 25P, respectively (FIG. 5A). B)). The plurality of space portions 33V1 have substantially the same shape, and each extend in a direction along the Y axis. The cross section along the XZ plane of each space portion 33V1 is rectangular. The width L in the direction along the X axis of each space portion 33V1 and the height in the direction along the Z axis are substantially equal to the width L25M and the height D25L of the line portion 25M of the master pattern 25P, respectively (FIG. 5A). (See (B)). Further, the period λ331 of the uneven shape in the direction along the X axis of the resin pattern 33P1 (that is, the total value of the width of one line portion 33M1 and the width of one space portion 33V1) is equal to the period λ25 of the master pattern 25P ( Equivalent to FIG. 5 (B).

(Judgment process)
As described above, after the resin pattern 33P1 is formed on the resin portion 33 above one virtual region 11A, the resin pattern 33P1 is formed on the resin portion 33 above the other virtual region 11A in the determination step S3-11. It is determined whether there is an area to be left. When the region where the resin pattern 33P1 is to be formed remains, as shown in FIG. 2, a series of steps from the wettability changing step S3-2 to the separation step S3-9 are performed for the region where the resin pattern 33P1 is to be formed. repeat. Here, when the wettability changing step S3-2 has already been performed for the other virtual region 11A, the region from the resin part forming step S3-3 to the separation step S3-9 is performed for the region where the resin pattern 33P1 is to be formed. A series of steps may be repeated. Further, when the wettability changing step S3-2 and the resin part forming step S3-3 are already performed for the other virtual region 11A, the step of separating the pressing region S3-5 from the pressing step S3-5 for the region where the resin pattern 33P1 is to be formed. What is necessary is just to repeat a series of process to S3-9. If there is no region where the resin pattern 33P1 is to be formed, the resin pattern forming step S3 is completed. A step of removing the burr 33b2 may be performed between the separation step S3-9 and the determination step S3-11 or between the determination step S3-11 and the step S5 covered with the silicon-containing resin layer. For removal of the burr 33b2, for example, a dry etching method such as an oxygen plasma treatment method can be used.

(Process of covering with silicon-containing resin layer)
After the resin pattern forming step S3, a step S5 of covering with the silicon-containing resin layer is performed. FIG. 8B is a diagram showing a cross section of the base body and the like for explaining the step of covering with the silicon-containing resin layer. In step S5 of covering with the silicon-containing resin layer, the resin portion 33 is covered with the silicon-containing resin layer 37. Thereby, the resin pattern 33P1 is embedded by the silicon-containing resin layer 37.

As the silicon-containing resin constituting the silicon-containing resin layer 37, for example, an organic silicon compound or the like can be used. Further, the ratio of silicon (Si) in the silicon-containing resin constituting the silicon-containing resin layer 37 is preferably 10 atomic% or more and 30 atomic% or less. This is because if the ratio of silicon in the silicon-containing resin is 10 atomic% or more, the etching selectivity with respect to the resin portion 33 of the silicon-containing resin layer 37 can be 10 or more in the resin pattern exposure step S7. If the proportion of silicon in the silicon-containing resin is 30 atomic% or less, the silicon-containing resin layer 37 becomes brittle due to oxidation of silicon in the silicon-containing resin layer 37 to form SiO _2. This is because it can be sufficiently suppressed.

(Resin pattern exposure process)
Subsequently, a resin pattern exposure step S7 is performed. FIG. 9A is a view showing a cross section of a base body and the like for explaining the resin pattern exposure step. In the resin pattern exposing step S7, a part of the silicon-containing resin layer 37 is etched to expose the line portion 33M1 of the resin pattern 33P1 of the resin portion 33. At this time, an etching method in which the etching rate for the silicon-containing resin layer 37 is higher than the etching rate for the resin portion 33 is used. In such an etching method, for example, as shown in FIG. 9 (A), a reaction using a mixed gas plasma of CF ₄ (tetrafluoromethane) gas and O ₂ (oxygen) gas as an etching gas 32. Ion etching method. Since an etching method is used in which the etching rate for the silicon-containing resin layer 37 is higher than the etching rate for the resin portion 33, this etching can be easily stopped when the line portion 33M1 is exposed.

The mixing ratio of CF ₄ (tetrafluoromethane) gas and O ₂ (oxygen) gas when etching a part of the silicon-containing resin layer 37 by the reactive ion etching method using the mixed gas plasma as the etching gas 32 is as follows: The partial pressure ratio is preferably in the range of 10: 1 to 5: 1. This is because when these mixing ratios are 5: 1 in terms of partial pressure ratio, or when the proportion of O ₂ (oxygen) gas is smaller than when the mixing ratio is 5: 1, the silicon-containing resin layer This is because it is possible to sufficiently suppress the silicon-containing resin layer 37 from becoming brittle due to oxidation of silicon in 37 to form SiO ₂ , and the mixing ratio thereof is 10: 1 or when the proportion of CF ₄ (tetrafluoromethane) gas is smaller than when the mixing ratio thereof is 10: 1, the etching of the silicon-containing resin layer 37 is hindered by the fluorocarbon-based product. Can be sufficiently suppressed.

(Inverted uneven pattern forming process)
Subsequently, a reverse concavo-convex pattern forming step S9 is performed. FIG. 9B is a diagram showing a cross-section of the base body and the like for explaining the reverse concavo-convex pattern forming step. In the reverse concavo-convex pattern forming step S9, the line portion 33M1 of the resin pattern 33P1 of the resin portion 33 is etched using the silicon-containing resin layer 37 as a mask. At this time, an etching method in which the etching rate for the resin portion 33 is higher than the etching rate for the insulating layer 15 is used. As such etching, for example, a reactive ion etching method using O ₂ (oxygen) gas as the etching gas 34 can be used. Since an etching method is used in which the etching rate for the resin portion 33 is higher than the etching rate for the insulating layer 15, this etching can be easily stopped when the insulating layer 15 is exposed.

  By this etching, as shown in FIG. 9B, a part of the resin portion 33 and the adhesion layer 17 is removed, and a hole 33h that penetrates the resin portion 33 and the adhesion layer 17 and reaches the insulating layer 15 is formed. . As a result, the inverted concavo-convex pattern 33P2 is formed in the resin portion 33. The inverted concavo-convex pattern 33P2 includes a plurality of line portions 33M2 that are convex portions protruding in the direction along the Z axis, and a plurality of space portions 33V2 that are concave portions recessed in the direction along the Z axis. Each line portion 33M2 has substantially the same shape, and extends in the direction along the Y axis. The cross section along the XZ plane of each line portion 33M2 is rectangular. Each space portion 33V2 has a substantially same shape, and extends in the direction along the Y-axis. The cross section along the XZ plane of each space portion 33V2 is rectangular. The inverted concavo-convex pattern 33P2 is a line and space pattern in which the line portions 33M2 and the space portions 33V2 are alternately and periodically arranged in the direction along the X axis.

  The reverse concavo-convex pattern 33P2 is the concavo-convex reverse pattern of the resin pattern 33P1 (see FIGS. 8A and 8B and FIG. 9A). Specifically, the space portion 33V2 of the inverted uneven pattern 33P2 is formed below the line portion 33M1 of the resin pattern 33P1, and the line portion 33M2 of the inverted uneven pattern 33P2 is formed below the space portion 33V1 of the resin pattern 33P1. ing. The period λ 332 of the concavo-convex shape in the direction along the X axis of the inverted concavo-convex pattern 33P2 (that is, the total value of the width of one line portion 33M2 and the width of one space portion 33V2) is the period λ 331 of the resin pattern 33P1. (See FIG. 8A).

(Insulating layer uneven pattern forming process)
After the inverted concavo-convex pattern forming step S9, an insulating layer concavo-convex pattern forming step S11 is performed. FIG. 10A is a diagram showing a cross-section of the base body and the like for explaining the insulating layer unevenness pattern forming step. In the insulating layer uneven pattern forming step S11, the exposed region of the insulating layer 15 is etched using the silicon-containing resin layer 37 and the resin portion 33 as a mask.

At this time, an etching method in which the etching rate for the insulating layer 15 is higher than the etching rate for the material of the upper surface 13u of the base body 13 (that is, the material constituting the uppermost layer (semiconductor layer 11) of the base body 13). Use. As such etching, for example, a reactive ion etching method using CF ₄ (tetrafluoromethane) gas as the etching gas 36 can be used. Since an etching method is used in which the etching rate for the insulating layer 15 is higher than the etching rate for the material of the upper surface 13 u of the base body 13, the etching can be easily stopped when the base body 13 is exposed. .

  By this etching, as shown in FIG. 10A, a part of the insulating layer 15 is removed, and an insulating layer uneven pattern 15P is formed in the insulating layer 15. The insulating layer concavo-convex pattern 15P includes a plurality of line portions 15M that are convex portions protruding in the direction along the Z axis, and a plurality of space portions 15V that are concave portions recessed in the direction along the Z axis. Each line portion 15M has a substantially same shape, and extends in the direction along the Y axis. The cross section along the XZ plane of each line portion 15M is rectangular. Each space portion 15V is substantially the same shape, and extends in the direction along the Y axis. The cross section along the XZ plane of each space portion 15V is rectangular. The insulating layer uneven pattern 15P is a line-and-space pattern in which the line portions 15M and the space portions 15V are alternately and periodically arranged in the direction along the X axis.

  The insulating layer uneven pattern 15P corresponds to the inverted uneven pattern 33P2 (see FIG. 9B). Specifically, the line portion 15M of the insulating layer uneven pattern 15P is formed below the line portion 33M2 of the inverted uneven pattern 33P2, and the space portion 15V of the insulating layer uneven pattern 15P is the space portion 33V2 of the inverted uneven pattern 33P2. Formed below. The period λ15 of the uneven shape in the direction along the X-axis of the insulating layer uneven pattern 15P (that is, the total value of the width of one line portion 15M and the width of one space portion 15V) is equal to that of the inverted uneven pattern 33P2. It is equal to the period λ332 (see FIG. 9B).

(Removal process)
After the insulating layer uneven pattern forming step S11, a removing step S13 is performed. FIG. 10B is a view showing a cross section of the base body portion and the like for explaining the removing step. As shown in FIG. 10B, in the insulating layer uneven pattern forming step S11, the silicon-containing resin layer 37, the resin portion 33, and the adhesion layer 17 are removed. The removal of the silicon-containing resin layer 37, the resin portion 33, and the adhesion layer 17 is performed by etching the silicon-containing resin layer 37, the resin portion 33, and the adhesion layer 17 rather than the etching rate for the semiconductor layer 11 and the insulating layer 15, for example. It can be performed by etching using an etching method having a higher rate. As such an etching method, for example, as shown in FIG. 10B, a reactive ion etching method using an O ₂ (oxygen) gas as an etching gas 38 can be cited.

(Substrate etching process)
Substrate etching step S15 is performed after removal step S13. FIG. 11A is a view showing a cross section of the base body portion and the like for explaining the base body etching step.

As shown in FIG. 11A, in the base body etching step S15, the base body body portion is etched by etching the semiconductor layer 11 of the base body portion 13 using the insulating layer 15 with the insulating layer uneven pattern 15P formed as a mask. The diffraction grating 11P is formed on the 13 semiconductor layers 11. Examples of the etching method used at this time include a reactive ion etching method using a mixed gas plasma of CH ₄ (methane) gas and H ₂ (hydrogen) gas as the etching gas 40.

  The diffraction grating 11P includes a plurality of line portions 11M that are convex portions projecting in the direction along the Z axis, and a plurality of space portions 11V that are concave portions recessed in the direction along the Z axis. Each line part 11M is substantially the same shape, and extends in the direction along the Y axis. The cross section along the XZ plane of each line portion 11M is rectangular. Each space part 11V is substantially the same shape, and extends in the direction along the Y axis. The cross section along the XZ plane of each space portion 11V is rectangular. The diffraction grating 11P is a line and space pattern in which the line portions 11M and the space portions 11V are alternately and periodically arranged in the direction along the X axis.

  The diffraction grating 11P corresponds to the insulating layer uneven pattern 15P. Specifically, the line part 11M of the diffraction grating 11P is formed below the line part 15M of the insulating layer uneven pattern 15P, and the space part 11V of the diffraction grating 11P is below the space part 15V of the insulating layer uneven pattern 15P. Is formed. The period λ11 of the uneven shape in the direction along the X axis of the diffraction grating 11P (that is, the total value of the width of one line portion 11M and the width of one space portion 11V) is the period of the insulating layer uneven pattern 15P. It is equal to λ15 (see FIG. 10A).

  The base body etching step S15 may be performed between the insulating layer uneven pattern forming step S11 and the removing step S13.

  The diffraction grating 11P is formed through the above steps.

  FIG. 11B is a view showing a cross section of the base body portion for illustrating the step of removing the insulating layer. When the insulating layer 15 is not necessary after the base body etching step S15, a step of removing the insulating layer 15 is performed as shown in FIG. The insulating layer 15 can be removed by cleaning with a hydrofluoric acid aqueous solution, for example.

  FIG. 12 is a partial cross-sectional perspective view of a distributed feedback semiconductor laser manufactured by using a resin pattern forming method by a nanoimprint method and a diffraction grating forming method according to the present embodiment.

  After the series of steps described above, as shown in FIG. 12, a buried layer 41 is formed on the semiconductor layer 11 on which the diffraction grating 11P is formed, for example, by metal organic vapor phase epitaxy. The buried layer 41 embeds the diffraction grating 11P. The buried layer 41 is made of a second conductivity type III-V group compound semiconductor such as InP. The buried layer 41 may be made of the same material as the semiconductor layer 11 or may be made of a different material. The semiconductor layer 11 and the buried layer 41 form a second cladding layer 42.

  Thereafter, the second cladding layer 42, the second optical confinement layer 9, the active layer 7, the first optical confinement layer 5 and the first cladding layer 3 are wet-etched to form a semiconductor mesa. Further, after forming the mesa buried layer 43 embedding the semiconductor mesa, the third cladding layer 45 is formed on the mesa buried layer 43 and the second cladding layer 42. The mesa buried layer 43 is made of, for example, a semi-insulating III-V compound semiconductor such as InP doped with Fe. The mesa buried layer 43 has a stacked structure in which a III-V group compound semiconductor layer made of a first conductivity type InP or the like and a III-V group compound semiconductor layer made of a second conductivity type InP or the like are stacked. Also good. The third cladding layer 45 is made of a III-V group compound semiconductor such as second conductivity type InP, for example. Note that the third cladding layer 45 may not be formed.

  Thereafter, the contact layer 47 and the upper electrode 49 are formed in this order on the third cladding layer 45. The contact layer 47 is made of a III-V group compound semiconductor such as a second conductivity type GaInAs. The upper electrode 49 has a laminated structure made of, for example, Ti / Pt / Au. A lower electrode 51 is formed on the back surface of the semiconductor substrate 1. The lower electrode 51 is made of, for example, an AuGeNi alloy. Through the above steps, the distributed feedback semiconductor laser 60 having the diffraction grating 11P can be manufactured.

  In the resin pattern forming method according to this embodiment as described above, in the wettability changing step S3-2, the wettability with respect to the resin portion 33 of the upper surface 19u of the base 19 is increased (FIGS. 2 and 6A). )reference).

  Therefore, in the pressing step S3-5, the protruding portion 33b1 pushed out of the contact area between the master pattern 25P of the mold 21 and the resin portion 33 in the resin portion 33 is the upper surface of the base 19 with a smaller contact angle θ33. 19u (see FIG. 7A). Thereby, it is suppressed that the protrusion part 33b1 reaches from the upper surface 19u of the base | substrate 19 to the side surface 25S of the raising part 25 of the mold 21. FIG. Therefore, even if the protruding portion 33b1 is cured and becomes a burr 33b2, it is possible to suppress the burr 33b2 from reaching the side surface 25S of the raised portion 25 of the mold 21 from the upper surface 19u of the base body 19, so that the burr 33b2 The height is suppressed (see FIG. 7B). As a result, according to the resin pattern forming method according to the present embodiment, it is possible to reduce the height of the burr 33b2 generated when the resin pattern 33P1 is formed.

  Furthermore, in the resin pattern forming method according to the present embodiment, in the wettability changing step S3-2, the wettability with respect to the resin portion 33 of the upper surface 19u of the base 19 and the raised portion 25 of the mold 21 are as follows. It is preferable to increase the wettability with respect to the resin part 33 of the upper surface 19u of the base 19 so that the difference between the wettability with respect to the resin part 33 of the side surface 25S increases (see FIGS. 6A and 7A). .

  That is, the smaller the difference between the wettability of the upper surface 19u of the base body 19 with respect to the resin portion 33 and the wettability of the side surface 25S of the raised portion 25 of the mold 21 with respect to the resin portion 33, the more the resin portion 33 is pressed in the pressing step S3-5. Of these, the protruding portion 33b1 pushed out of the contact area between the master pattern 25P of the mold 21 and the resin portion 33 tends to contact both the upper surface 19u of the base 19 and the side surface 25S of the raised portion 25 of the mold 21, in other words. Then, the tendency that the protruding portion 33b1 extends from the upper surface 19u of the base 19 to the side surface 25S of the raised portion 25 of the mold 21 is increased. Therefore, by increasing the difference between the wettability with respect to the resin portion 33 of the upper surface 19u of the base body 19 and the wettability with respect to the resin portion 33 of the side surface 25S of the raised portion 25 of the mold 21 in the wettability changing step S3-2. It is possible to further reduce the height of the burr 33b2 generated when the pattern 33P1 is formed (see FIG. 7B).

  Further, according to the method for forming a diffraction grating according to the present embodiment, the resin pattern 33P1 is formed by the resin pattern forming method according to the present embodiment as described above, and thus occurs when the resin pattern 33P1 is formed. It becomes possible to reduce the height of the burr 33b2. As a result, it is possible to reduce problems caused by the presence of the burr 33b2 when forming the diffraction grating 11P.

  Furthermore, in the method for forming a diffraction grating according to the present embodiment, the base body portion 13 is etched using the insulating layer 15 on which the insulating layer uneven pattern 15P is formed as a mask, so that the diffraction grating 11P is formed on the base body portion 13. (See FIGS. 10B and 11A). Here, the formation of the insulating layer uneven pattern 15P is performed by selectively forming the silicon-containing resin layer 37, the resin portion 33, and the insulating layer 15 in this order after forming the resin pattern 33P1 on the resin portion 33 in the resin pattern forming step S3. This is performed by etching (see FIGS. 7A to 11A). Therefore, even if the flatness of the upper surface 13u of the base body 13 is poor and the thickness of the resin pattern 33P1 of the resin part 33 varies due to the poor flatness (see FIG. 8A), The influence of the variation on the shape of the diffraction grating 11P formed in the base body 13 is reduced. In addition, the depth of the concave portion (in this embodiment, the space portion 11V) of the diffraction grating 11P formed in the base body portion 13 in the base body etching step S15 is such that the base body portion 13 is etched using the insulating layer 15 as a mask. It can be accurately controlled by time (see FIG. 11A).

(Second Embodiment)
Next, a distributed feedback semiconductor laser manufacturing method using the resin pattern forming method by the nanoimprint method and the diffraction grating forming method according to the second embodiment will be described. In the following description of each embodiment, the same reference numerals as those in the first embodiment are attached, and the detailed description thereof may be omitted.

  This embodiment is different from the first embodiment in terms of the content of the wettability changing step S3-2.

(Wettability change process)
FIG. 13 is a view showing a cross section of a mold for explaining the wettability changing step of the present embodiment. In the wettability changing step S <b> 3-2 of the present embodiment, a process of reducing wettability with respect to the resin portion 33 of the side surface 25 </ b> S of the raised portion 25 of the mold 21 is performed. Specifically, in the present embodiment, as shown in FIG. 13, the side surface 25 </ b> S of the raised portion 25 of the mold 21 is a coating material whose wettability with respect to the resin portion 33 is lower than the wettability with respect to the resin portion 33 of the side surface 25 </ b> S. Coat with 63. In this way, the mold 21B in which the side surface 25S is coated with the coating material 63 is prepared. In this case, the surface of the coating material 63 newly becomes the side surface 25S2 of the raised portion 25 of the mold 21B.

  As the coating material 63, for example, fluorine such as OPTOOL DSX manufactured by Daikin Industries, Ltd., fluorine resin such as 3M NovecEGC-1720 and Teflon (registered trademark), or the like can be used. In particular, when a fluorine-based resin is used as the coating material 63, the leakage of the side surface 25S2 of the raised portion 25 of the mold 21 to the resin portion 33 can be easily reduced.

(Pressing process)
FIG. 14 is a view showing a cross section of a base body and the like for explaining the pressing step of the present embodiment. As shown in FIG. 14, in the pressing step S <b> 3-5 of the present embodiment, the pattern surface 25 </ b> F of the mold 21 </ b> B is opposed to the surface on one virtual region 11 </ b> A of the upper surface 19 u of the base 19. As shown in FIG. 16, the pattern surface 25 </ b> F is pressed against the resin portion 33. A part of the resin portion 33 against which the pattern surface 25F is pressed is pushed out to the outside of the contact area between the pattern surface 25F and the resin portion 33 to become a protruding portion 33b1.

(Curing process)
The curing step S3-7 of the present embodiment is the same as the curing step S3-7 of the first embodiment. That is, the curing step S3-7 is performed after the pressing step S3-5. FIG. 15 is a view showing a cross section of a substrate and the like for explaining the curing step.

  As shown in FIG. 15, in the curing step S <b> 3-7, the resin part 33 is irradiated with ultraviolet rays to cure the resin part 33 in a state where the pattern surface 25 </ b> F is pressed against the resin part 33. As a result, the protruding portion 33b1 is also cured and becomes a burr 33b2. In this manner, the resin pattern 33P1, which is a transfer pattern of the master pattern 25P, is fixed to the resin portion 33.

  In the resin pattern forming method according to the present embodiment as described above, in the wettability changing step S3-2, the wettability of the side surface 25S of the raised portion 25 of the mold 21 with respect to the resin portion 33 is reduced (see FIG. 13). ).

  Therefore, in the pressing step S <b> 3-5, in the resin portion 33, the protruding portion 33 b 1 pushed out of the contact area between the master pattern 25 </ b> P of the mold 21 and the resin portion 33 is the side surface 25 </ b> S <b> 2 of the raised portion 25 of the mold 21. Can contact the side surface 25S2 of the mold 21 only when the contact angle is large (see FIG. 15). As a result, the protruding portion 33b1 is unlikely to come into contact with the side surface 25S2 of the raised portion 25 of the mold 21, so that the protruding portion 33b1 is prevented from extending from the upper surface 19u of the base body 19 to the side surface 25S2 of the raised portion 25 of the mold 21. The As a result, even if the protruding portion 33b1 is hardened to become a burr 33b2, it is possible to suppress the burr 33b2 from reaching the side surface 25S2 of the raised portion 25 of the mold 21 from the upper surface 19u of the base body 19; Is suppressed (see FIG. 17). As a result, according to the resin pattern forming method according to the present embodiment, it is possible to reduce the height of the burr 33b2 generated when the resin pattern 33P1 is formed.

  Furthermore, in the resin pattern forming method according to the present embodiment, in the wettability changing step S3-2, the wettability with respect to the resin portion 33 of the side surface 25S of the raised portion 25 of the mold 21 and the base 19 is changed for the following reasons. It is preferable to reduce the wettability of the side surface 25S of the raised portion 25 of the mold 21 with respect to the resin portion 33 so that the difference between the wettability of the upper surface 19u and the resin portion 33 increases.

  That is, the smaller the difference between the wettability of the side surface 25S of the raised portion 25 of the mold 21 with respect to the resin portion 33 and the wettability of the upper surface 19u of the base 19 with respect to the resin portion 33, the more the resin portion 33 is pressed in the pressing step S3-5. Among these, the protruding portion 33b1 pushed out of the contact area between the master pattern 25P of the mold 21 and the resin portion 33 is both the upper surface 19u of the base 19 and the side surface 25S (or side surface 25S2) of the raised portion 25 of the mold 21. In other words, the tendency that the protruding portion 33b1 extends from the base body 19 of the base body 19 to the side surface 25S (or the side surface 25S2) of the raised portion 25 of the mold 21 is increased. Therefore, the resin pattern is increased by increasing the difference between the wettability with respect to the resin part 33 of the side surface 25S of the raised portion 25 of the mold 21 and the wettability with respect to the resin part 33 of the upper surface 19u of the base body 19 in the wettability changing step S3-2. It is possible to further reduce the height of the burr 33b2 generated when forming 33P1 (see FIG. 17).

  Further, according to the diffraction grating forming method according to the present embodiment as described above, the resin pattern 33P1 is formed by the resin pattern forming method according to the present embodiment as described above, and thus the resin pattern 33P1 is formed. It is possible to reduce the height of the burr 33b2 that is generated during the process. As a result, it is possible to reduce problems caused by the presence of the burr 33b2 when forming the diffraction grating 11P.

  Furthermore, for the same reason as the method for forming a diffraction grating according to the first embodiment, the flatness of the upper surface 13u of the base body 13 is poor, and the thickness of the resin pattern 33P1 of the resin part 33 due to the poor flatness. Even if there is a variation in the thickness (see FIG. 8A), the influence of this variation on the shape of the diffraction grating 11P formed in the base body 13 is reduced. In addition, the depth of the concave portion (space portion 11V) of the diffraction grating 11P formed in the base body portion 13 in the base body etching step S15 is accurately controlled by the etching time of the base body portion 13 using the insulating layer 15 as a mask. It is possible (see FIG. 11A).

  In the present embodiment, in the wettability changing step S3-2, in addition to the process of reducing the wettability of the side surface 25S of the raised portion 25 of the mold 21 with respect to the resin portion 33 as described above, The same process as in the wettability changing step S3-2, that is, a process of increasing the wettability of the upper surface 19u of the base 19 with respect to the resin portion 33 may be further performed. Thereby, it is possible to further reduce the height of the burr 33b2 generated when the resin pattern 33P1 is formed.

(Third embodiment)
Next, a distributed feedback semiconductor laser manufacturing method using the resin pattern forming method by the nanoimprint method and the diffraction grating forming method according to the third embodiment will be described.

  FIG. 16 is a flowchart showing a method for forming a diffraction grating according to this embodiment.

  As shown in FIG. 16, the diffraction grating forming method of the present embodiment includes a step S5 of covering with a silicon-containing resin layer, a resin pattern exposing step S7, a reverse concavo-convex pattern forming step S9, an insulating layer concavo-convex pattern forming step S11, and The method is different from the diffraction grating forming method of the first embodiment in that the removal step S13 is not included (see FIG. 1). The resin pattern formation method of this embodiment is the same as the resin pattern formation method of 1st Embodiment (refer FIG. 2).

(Substrate formation process)
In the substrate forming step S1 of the present embodiment, the substrate main body portion 13 is formed as in the case of the substrate forming step S1 of the first embodiment, but the insulating layer 15 and the adhesion layer 17 are formed on the substrate main body portion 13. No (see FIG. 4 and FIG. 17A). Therefore, in the present embodiment, the base body portion 13 also corresponds to the base body 19. In order to improve the adhesion between the semiconductor layer 11 and the resin part 33, the adhesion layer 17 may be formed between the semiconductor layer 11 and the resin part 33.

(Resin pattern forming process)
FIG. 17A is a view showing a cross section of the base body portion and the like for explaining the resin pattern forming step of the present embodiment. The resin pattern forming step S3 of the present embodiment is the same as the resin pattern forming step S3 of the first embodiment, except that the base body 19 is changed to the base body portion 13. In the present embodiment, as shown in FIG. 17A, the resin portion 33 having the resin pattern 33P1 is formed on the semiconductor layer 11 of the base body portion 13.

(Substrate etching process)
FIG. 17B is a view showing a partial cross section of the base body portion for illustrating the base body etching process of the present embodiment. As shown in FIG. 17B, in the substrate etching step S15 of the present embodiment, the resin portion 33 and the semiconductor layer 11 are etched to form a shape corresponding to the resin pattern 33P1 in the semiconductor layer 11. For example, the resin part 33 is etched until the semiconductor layer 11 is exposed in a region corresponding to the space part 33V1 of the resin pattern 33P1 by a reactive ion plasma etching method using O ₂ (oxygen) gas, and then CH ₄ ( This is achieved by etching the semiconductor layer 11 by a reactive ion etching method using a mixed gas of methane) and H ₂ (hydrogen). Thereby, the diffraction grating 11 </ b> P is formed in the semiconductor layer 11.

  The diffraction grating 11P has an uneven shape corresponding to the resin pattern 33P1, but due to the difference in etching rate between the resin portion 33 and the semiconductor layer 11, the length of the uneven shape of the diffraction grating 11P in the Z-axis direction is the resin. It may be different from the length in the Z-axis direction of the uneven shape of the pattern 33P1.

  According to the resin pattern forming method according to the present embodiment as described above, the height of the burr 33b2 generated when the resin pattern 33P1 is formed is reduced for the same reason as in the resin pattern forming method according to the first embodiment. (See FIG. 17A). As a result, it is possible to reduce problems caused by the presence of burrs during pattern formation.

  Further, according to the diffraction grating forming method according to the present embodiment as described above, the resin pattern 33P1 is formed by the resin pattern forming method according to the present embodiment as described above, and thus the resin pattern 33P1 is formed. It is possible to reduce the height of the burr 33b2 that is generated during the process. As a result, it is possible to reduce problems caused by the presence of the burr 33b2 when forming the diffraction grating 11P.

  Furthermore, for the same reason as the method for forming a diffraction grating according to the first embodiment, the flatness of the upper surface 13u of the base body 13 is poor, and the thickness of the resin pattern 33P1 of the resin part 33 due to the poor flatness. Even if there is a variation in the thickness (see FIG. 8A), the influence of this variation on the shape of the diffraction grating 11P formed in the base body 13 is reduced. In addition, the depth of the concave portion (space portion 11V) of the diffraction grating 11P formed in the base body portion 13 in the base body etching step S15 is accurately controlled by the etching time of the base body portion 13 using the insulating layer 15 as a mask. It is possible (see FIG. 11A).

  Furthermore, according to the method for forming a diffraction grating according to the present embodiment as described above, the number of steps required is smaller than that for the method for forming a diffraction grating according to the first embodiment, and therefore a series of steps necessary for pattern formation is performed. It can be simplified.

  In addition, in the resin pattern formation method of this embodiment, in addition to the process which increases the wettability with respect to the resin part 33 of the upper surface 19u of the base | substrate 19 in wettability change process S3-2, it replaces with this process. The same process as in the wettability changing process S3-2 of the second embodiment, that is, the process of reducing the wettability of the side surface 25S of the raised part 25 of the mold 21 with respect to the resin part 33 may be performed.

  DESCRIPTION OF SYMBOLS 19 ... Base | substrate, 13 ... Base | substrate main-body part, 19u ... Upper surface, 21 ... Mold, 25 ... Raised part, 25P ... Master pattern, 33 ... Resin part, 33P1 ... -Resin pattern, S1 ... Substrate formation step, S3 ... Resin pattern formation step, S3-1 ... Mold preparation step, S3-2 ... Wetting property change step, S3-3 ... Resin part Formation process, S3-3-1 ... wettability increasing process, S3-5 ... pressing process, S3-7 ... curing process, S3-9 ... separation process, S3-11 ... determination Step, S5: Covering with silicon-containing resin layer, S7: Resin pattern exposing step, S9: Inverted concave / convex pattern forming step, S11 ... Insulating layer concave / convex pattern forming step, S13 ... Removing step , S15... Substrate etching process.

Claims (9)

A resin pattern forming method by a nanoimprint method,
A mold preparation step of preparing a mold having a mold base part and a raised part provided on the upper surface of a master pattern for nanoimprint, which is provided on the mold base part and formed of a concavo-convex pattern,
A wettability changing step for changing the wettability;
A resin part forming step of forming the resin part made of an ultraviolet curable resin on a substrate;
A pressing step of pressing the mold against the resin part;
A curing step of transferring the master pattern to the resin portion by irradiating the resin portion with ultraviolet rays while the mold is pressed against the resin portion, and curing the resin portion;
A separation step of forming the resin pattern on the resin portion by separating the mold from the resin portion;
With
In the wettability changing step, the wettability of the upper surface of the base with respect to the resin portion is increased and / or the wettability of the side surface of the raised portion of the mold with respect to the resin portion is reduced. Pattern forming method.   In the wettability changing step, the difference between the wettability of the upper surface of the base with respect to the resin portion and the wettability of the side surface of the raised portion of the mold with respect to the resin portion is increased. The resin pattern forming method according to claim 1, wherein wettability of the upper surface with respect to the resin portion is increased.   3. The resin pattern according to claim 1, wherein in the wettability changing step, wettability of the upper surface of the substrate with respect to the resin portion is increased by performing oxygen plasma treatment on the upper surface of the substrate. Forming method.   In the wettability changing step, the mold of the mold is increased such that a difference between the wettability of the side surface of the raised portion of the mold with respect to the resin portion and the wettability of the upper surface of the base with respect to the resin portion is increased. The resin pattern forming method according to any one of claims 1 to 3, wherein wettability of the side surface of the raised portion to the resin portion is reduced.   In the wettability changing step, the side surface of the raised portion of the mold is coated with a coating material whose wettability with respect to the resin portion is lower than the wettability with respect to the resin portion of the side surface. The resin pattern forming method according to claim 1, wherein wettability of the side surface of the portion with respect to the resin portion is reduced.   The method for forming a resin pattern according to claim 5, wherein the coating material is a fluororesin. A method of forming a diffraction grating by a nanoimprint method,
A base body forming step of forming a base body having a base body portion and an insulating layer provided on the base body portion;
A resin pattern forming step of forming the resin pattern on the resin portion on the substrate by the resin pattern forming method according to any one of claims 1 to 6 after the substrate forming step;
After the resin pattern formation step, the step of covering the resin portion with a silicon-containing resin layer,
A resin pattern exposing step of exposing a convex portion of the resin pattern of the resin portion by etching a part of the silicon-containing resin layer;
After the resin pattern exposing step, etching the convex portion of the resin pattern of the resin portion exposed using the silicon-containing resin layer as a mask, and penetrating the resin portion to reach the insulating layer A reversal concavo-convex pattern forming step of forming a reverse concavo-convex pattern, which is a concavo-convex reverse pattern of the resin pattern, on the resin portion
After the reverse concavo-convex pattern forming step, the insulating layer concavo-convex pattern corresponding to the reverse concavo-convex pattern of the resin portion is insulated by etching the insulating layer using the silicon-containing resin layer and the resin portion as a mask. An insulating layer uneven pattern forming step to be formed on the layer;
After the insulating layer uneven pattern forming step, a removal step of removing the silicon-containing resin layer and the resin portion,
Substrate etching step for forming the diffraction grating corresponding to the insulating layer concavo-convex pattern in the base body portion by etching the base body portion using the insulating layer as a mask after the insulating layer concavo-convex pattern forming step. When,
With
The ultraviolet curable resin is a silicon-free resin,
The insulating layer is made of a material different from the material of the upper surface of the base body portion,
In the resin pattern exposing step, etching the part of the silicon-containing resin layer by an etching method having a higher etching rate for the silicon-containing resin layer than an etching rate for the resin portion,
In the inverted concavo-convex pattern forming step, etching the convex portions of the resin pattern of the resin portion exposed by an etching method having an etching rate higher than that of the insulating layer relative to the resin portion,
In the insulating layer uneven pattern forming step, the insulating layer is etched by an etching method in which an etching rate for the insulating layer is higher than an etching rate for the material of the upper surface of the base body portion. Forming method. A method of forming a diffraction grating by a nanoimprint method,
A resin pattern forming step of forming the resin pattern on the resin portion on the base by the resin pattern forming method according to claim 1,
Substrate etching step of forming the diffraction grating corresponding to the resin pattern on the substrate by etching the resin portion and the substrate after the resin pattern forming step;
A method of forming a diffraction grating, comprising: The substrate comprises a semiconductor material;
9. The method of forming a diffraction grating according to claim 7, wherein the diffraction grating formed in the substrate etching step is a diffraction grating of a distributed feedback semiconductor laser.

Images