JP2008123574A - Stamper original plate for optical information recording medium, and method for manufacturing stamper for optical information recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a stamper original plate for an optical information recording medium having two or more fine rugged shapes, and also to manufacture a stamper. <P>SOLUTION: A resist layer 52 is formed on a silicon wafer 51, the resist layer 52 is irradiated with an electron beam to form a prescribed pattern, the resist layer 52 is developed to remove a part irradiated with the electron beam and reactive ion etching is performed to the surface of the silicon wafer 51 exposed by development, so that the two or more rugged shapes having ≤60 nm depths different from each other are formed on the surface of the silicon wafer 51. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical information recording medium stamper master and an optical information recording medium stamper manufacturing method.

  2. Description of the Related Art In recent years, with the demand for higher density optical information recording media, high-density optical information recording media that perform recording and / or reproduction using laser light of 450 nm or less have been developed. This high-density optical information recording medium is manufactured by applying a dye on a resin substrate on which grooves used for laser beam tracking are formed, and further attaching a substrate for protecting the dye recording layer. The resin substrate at this time can be manufactured by using, as one of the molds, a metal stamper having a surface shape obtained by inverting the groove pattern when performing resin injection molding.

  Further, this stamper is duplicated based on the uneven pattern of the stamper original. Therefore, it is necessary to form a concavo-convex pattern necessary for a resin substrate for an optical information recording medium on the stamper master. The concave / convex pattern becomes finer as the density of the optical information recording medium increases, and with the diversification of information recorded in advance on the optical information recording medium, it is required to form a plurality of types of fine concave / convex patterns.

Until now, as a fine processing technique, a technique for forming a minute uneven pattern on a substrate by irradiating an electron beam is known (for example, Patent Documents 1 to 3).
Further, Patent Document 4 discloses a technique for performing fine processing by forming a pattern with an electron beam on a recording layer of a phase change optical disc and removing the Si film by RIE (Reactive Ion Etching). ing.

JP 2001-277200 A JP 2002-298448 A JP 2004-163698 A JP-A-2005-100526

  By the way, according to detailed studies by the inventors, when data is recorded on a dye-based optical information recording medium with a laser beam having a short wavelength as described above, the signal of the recording medium depends on the groove shape of the resin substrate. It was found that the characteristics changed greatly. Further, according to the research, in a dye-based optical information recording medium using a laser beam with a short wavelength, it is necessary to form two or more groove shapes having a depth of 60 nm or less and different depths on the substrate. However, it is not easy to form such an uneven shape.

  The present invention has been made in view of the background as described above, and provides a stamper for an optical information recording medium having two or more groove shapes that are extremely fine and different in depth, and a method for manufacturing a stamper master. Is an issue.

  A method of manufacturing a stamper master for an optical information recording medium that solves the above-described problems includes a resist layer forming step of forming a resist layer on a Si-containing substrate, and irradiating the resist layer with an electron beam to draw a predetermined pattern An electron beam irradiation step, developing the resist layer, removing a portion irradiated with the electron beam or a portion not irradiated, and the surface of the Si-containing substrate exposed by the development step, And an etching step of forming a concavo-convex shape including two or more kinds of grooves having a depth of 60 nm or less and different depths on the surface of the Si-containing substrate by performing reactive ion etching.

  In this manner, fine drawing can be performed by irradiating the resist layer formed on the Si substrate with the electron beam. Then, by performing reactive ion etching, an uneven shape having a size corresponding to the drawing can be formed.

  Here, the optical information recording medium stamper and the optical information recording medium stamper manufactured by the manufacturing method of the present invention are used for manufacturing a dye-based optical information recording medium with a short wavelength laser beam. For example, in the currently proposed Blu-ray Disc specification, a management information recording area (for example, a BCA area) in which information such as disc information is recorded is formed on the inner periphery of the optical information recording medium. The BCA area is an area corresponding to an area where a BCA signal is recorded. FIG. 1 is a plan view of a stamper master for producing this optical information recording medium, and hatching indicates a region. As shown in FIG. 1, the disk-shaped stamper master 50 has a data storage area A1 in which a first pregroove is formed in a spiral shape (not shown) in a donut-shaped area. A BCA area A2 is formed on the inner peripheral side of the data storage area A1. A spiral (not shown) second pregroove is also formed in the BCA region.

  In an optical information recording medium manufactured using the stamper master 50 (specifically, manufactured using a stamper manufactured from the stamper master 50), a BCA signal is transmitted to the dye recording layer and / or the reflective layer by a laser. It is formed into a barcode by light. A pre-groove (second pre-groove) needs to be formed in the BCA area, but the groove depth is preferably formed shallower than the pre-groove (first pre-groove) in the data recording area.

  As described above, the two or more types of grooves having different depths include a first pregroove formed in a spiral shape and a second pregroove formed in a spiral shape on the inner peripheral side of the first pregroup. In addition, when the depth of the first pregroove is a and the depth of the second pregroove is b, it is desirable that a> b is satisfied.

The first pregroove may be formed as a data storage area, and the second pregroove may be formed as a management information storage area (BCA).
The depth a of the first pregroove is preferably 30 to 50 nm, and the depth b of the second pregroove is preferably 5 to 30 nm.

  In the electron beam irradiation step, it is desirable to draw the pattern with two or more different line widths. By doing in this way, the groove | channel of 2 or more types of different depths according to the said line | wire width can be formed in the said etching process.

  The method of manufacturing a stamper for an optical information recording medium using the stamper original plate for an optical information recording medium manufactured by the above-described method forms a conductive layer on the surface on which the concavo-convex shape of the stamper original plate for an optical information recording medium is formed. A thin film forming step, a plating step of forming a metal plate including the conductive layer by electroplating on the conductive layer, a peeling step of peeling the metal plate from the stamper master for the optical information recording medium, And a punching step of punching the peeled metal plate into a predetermined shape.

After the metal plate is formed, it is desirable to peel the metal plate in a liquid having the same temperature as the plating solution used in the plating step.
The temperature of the liquid is preferably within ± 5 ° C. with respect to the temperature of the plating solution.

  Furthermore, after applying and drying a protective film on the surface of the metal plate punched in the punching process, the back surface of the metal plate is polished and smoothed by a dry or wet method. desirable.

  In addition, after the plating process, in order to confirm the state of the formed groove shape, it is preferable to provide an inspection process for inspecting the metal plate by an electric signal inspection apparatus.

  In the inspection step, it is desirable to provide a cover layer on the surface of the metal plate before the inspection is performed. After the inspection step, the cover layer is removed and oxygen plasma treatment is performed on the surface of the metal plate. Is desirable.

  In the optical information recording medium stamper manufacturing method described above, the optical information recording medium stamper may be manufactured a plurality of times from one optical information recording medium stamper master. That is, by using a plate obtained by transferring a stamper original plate as a stamper for an optical information recording medium, it is possible to increase the accuracy of the uneven shape of the stamper.

  According to the present invention, an optical information recording medium stamper master and a stamper having two or more kinds of fine irregularities can be manufactured with high accuracy.

  Next, the optical information recording medium stamper (hereinafter simply referred to as “stamper”) manufacturing method and the optical information recording medium stamper original plate (hereinafter simply referred to as “stamper original plate”) manufacturing method of the present invention. Such an embodiment will be described in detail with reference to the drawings as appropriate.

First, an example of a stamper original plate manufactured by the manufacturing method of the present invention or an optical information recording medium manufactured by a stamper will be described.
In the drawings to be referred to, FIG. 2 is a diagram for explaining a groove depth, and FIG. 3 is a cross-sectional view showing a layer structure of an optical information recording medium using a stamper original plate or a stamper manufactured by the manufacturing method of the present invention. FIG.

  As shown in FIG. 3, the optical information recording medium 10 includes a write-once recording layer 14 containing a dye and a cover layer having a thickness of 0.01 to 0.5 mm on a substrate 12 having a thickness of 0.7 to 2 mm. 16 in this order. Specifically, for example, the light reflection layer 18, the write-once recording layer 14, the barrier layer 20, the adhesive layer 22, and the cover layer 16 are provided on the substrate 12 in this order.

[Substrate 12]
As shown in FIG. 3, the substrate 12 of the preferred optical information recording medium 10 has a first pregroove 34 (guide groove) having a shape in which the track pitch, groove width, groove depth, and wobble amplitude are in the following ranges. A second pregroove 35 is formed.
As shown in FIG. 2, the groove depth is measured by a width W (half-value width) at a half depth position when the depth is H.
The first pregroove 34 is provided in order to achieve a higher recording density than CD-R and DVD-R. For example, the optical information recording medium 10 is used as a medium corresponding to a blue-violet laser. It is suitable for use.
The second pregroove 35 has a slightly smaller groove width and groove depth than the first pregroove 34, and is provided on the inner circumference side of the optical information recording medium 10 when it is disc-shaped. The second pregroove 35 is used as a BCA area in which, for example, manufacturer information of the optical information recording medium 10 and other management information are recorded. In the BCA area, the reflectivity needs to be lower than that of the data storage area in terms of signal characteristics, so that the groove width is shallower than that of the data storage area.

  The track pitch of the first pregroove 34 is, for example, about 320 nm, and can be appropriately changed according to the specifications of the optical information recording medium.

The groove width (half width) of the first pregroove 34 is desirably in the range of 90 to 180 nm.
If the groove width of the first pregroove 34 is less than 90 nm, the groove may not be sufficiently transferred during molding or the recording error rate may increase. If it exceeds 180 nm, the pits formed during recording spread. As a result, crosstalk may occur or a sufficient degree of modulation may not be obtained.

  The groove depth a of the first pregroove 34 is 60 nm or less, preferably 30 to 50 nm, more preferably 35 to 45 nm. If the groove depth of the first pre-groove 34 is less than 5 nm, a sufficient recording modulation degree may not be obtained, and if it exceeds 60 nm, the reflectance may be significantly lowered.

Further, the upper limit of the groove inclination angle of the first pregroove 34 is preferably 80 ° or less, more preferably 70 ° or less, further preferably 60 ° or less, and 50 ° or less. It is particularly preferred. Further, the lower limit value is preferably 20 ° or more, more preferably 30 ° or more, and further preferably 40 ° or more.
If the groove inclination angle of the first pregroove 34 is less than 20 °, a sufficient tracking error signal amplitude may not be obtained. If it exceeds 80 °, it is difficult to mold the substrate 12 (such as injection molding).

  The groove depth b of the second pregroove 35 is in the range of 5 to 30 nm, and more preferably in the range of 8 to 17 nm.

  The groove width (half-value width) of the second pregroove 35 is appropriately set within a range in which the groove depth can be obtained.

  A preferable groove inclination angle of the second pregroove 35 is the same as that of the first pregroove 34.

  As the substrate 12 used in the optical information recording medium 10, various materials used as substrate materials for conventional optical information recording media can be arbitrarily selected and used.

Among the substrate materials, thermoplastic resins such as amorphous polyolefin and polycarbonate are preferable, and polycarbonate is particularly preferable from the viewpoints of moisture resistance, dimensional stability, and low cost.
When these resins are used, the substrate 12 can be manufactured by injection molding.

Moreover, the thickness of the board | substrate 12 is the range of 0.7-2 mm, it is preferable that it is the range of 0.9-1.6 mm, and it is more preferable to set it as 1.0-1.3 mm.
In addition, it is preferable to form an undercoat layer on the surface of the substrate 12 on the side where the light reflecting layer 18 described later is provided for the purpose of improving the flatness and the adhesive force.

[Write-once recording layer 14]
The write-once recording layer 14 of the preferred optical information recording medium 10 is prepared by dissolving a dye in a suitable solvent together with a binder or the like to prepare a coating solution, and then applying this coating solution on a substrate or a light reflecting layer 18 described later. It is formed by applying a coating film on the top and then drying. Here, the write-once recording layer 14 may be a single layer or a multilayer. In the case of a multilayer structure, the step of applying the coating liquid is performed a plurality of times.
Examples of the coating method include a spray method, a spin coating method, a dip method, a roll coating method, a blade coating method, a doctor roll method, and a screen printing method.

  The thickness of the write-once recording layer 14 formed in this manner is preferably 300 nm or less, more preferably 250 nm or less, and more preferably 200 nm or less on the groove 38 (convex portion in the substrate 12). More preferably, it is particularly preferably 180 nm or less. The lower limit is preferably 30 nm or more, more preferably 50 nm or more, further preferably 70 nm or more, and particularly preferably 90 nm or more.

  Further, the thickness of the write-once recording layer 14 is preferably 400 nm or less, more preferably 300 nm or less, and further preferably 250 nm or less on the land 40 (a concave portion in the substrate 12). The lower limit is preferably 70 nm or more, more preferably 90 nm or more, and further preferably 110 nm or more.

  Further, the ratio (t1 / t2) between the thickness t1 of the write-once recording layer 14 on the groove 38 and the thickness t2 of the write-once recording layer 14 on the land 40 is preferably 0.4 or more, It is more preferably 0.5 or more, further preferably 0.6 or more, and particularly preferably 0.7 or more. The upper limit value is preferably less than 1, more preferably 0.9 or less, further preferably 0.85 or less, and particularly preferably 0.8 or less.

[Cover layer 16]
The cover layer 16 of the preferred optical information recording medium 10 is bonded to the write-once recording layer 14 described above or a barrier layer 20 described later via an adhesive layer 22 made of an adhesive, an adhesive, or the like.

The cover layer 16 used in the optical information recording medium 10 is not particularly limited as long as it is a transparent film, but is not limited to acrylic resins such as polycarbonate and polymethyl methacrylate; chlorides such as polyvinyl chloride and vinyl chloride copolymers. It is preferable to use vinyl resin; epoxy resin; amorphous polyolefin; polyester; cellulose triacetate. Among them, it is more preferable to use polycarbonate or cellulose triacetate.
Note that “transparent” means that the transmittance is 80% or more with respect to light used for recording and reproduction.

  The cover layer 16 may contain various additives as long as the effects of the present invention are not hindered. For example, a UV absorber for cutting light having a wavelength of 400 nm or less and / or a dye for cutting light having a wavelength of 500 nm or more may be contained.

Further, as the surface physical properties of the cover layer 16, it is preferable that both the two-dimensional roughness parameter and the three-dimensional roughness parameter have a surface roughness of 5 nm or less.
Further, from the viewpoint of the concentration of light used for recording and reproduction, the birefringence of the cover layer 16 is preferably 10 nm or less.

  The thickness of the cover layer 16 is appropriately determined by the wavelength of the laser beam 46 irradiated for recording and reproduction and the NA of the objective lens 45. In the optical information recording medium 10, the thickness of the cover layer 16 is 0.01-0. Within the range of 0.5 mm, more preferably within the range of 0.05 to 0.12 mm.

  Further, the total thickness of the cover layer 16 and the adhesive layer 22 is preferably 0.09 to 0.11 mm, and more preferably 0.095 to 0.105 mm.

  The light incident surface of the cover layer 16 may be provided with a hard coat layer 44 (protective layer) for preventing the light incident surface from being damaged when the optical information recording medium 10 is manufactured.

  As the adhesive used for the adhesive layer 22, for example, a UV curable resin, an EB curable resin, a thermosetting resin or the like is preferably used, and in particular, a UV curable resin is preferably used.

  When using a UV curable resin as an adhesive, prepare the coating solution by dissolving the UV curable resin as it is or in an appropriate solvent such as methyl ethyl ketone or ethyl acetate, and supply it to the surface of the barrier layer 20 from the dispenser. Also good. Further, in order to prevent warping of the optical information recording medium 10 to be produced, it is preferable that the UV curable resin constituting the adhesive layer 22 has a small curing shrinkage rate. Examples of such UV curable resins include UV curable resins such as “SD-640” manufactured by Dainippon Ink and Chemicals, Inc.

  For example, a predetermined amount of the adhesive is applied onto the bonding surface including the barrier layer 20, and the cover layer 16 is placed thereon. Then, the adhesive is applied by spin coating to the bonding surface and the cover layer. It is preferable to cure the film after it has been uniformly spread between the two.

  The thickness of the adhesive layer 22 made of such an adhesive is preferably in the range of 0.1 to 100 μm, more preferably in the range of 0.5 to 50 μm, and still more preferably in the range of 10 to 30 μm.

  As the pressure-sensitive adhesive used for the adhesive layer 22, acrylic, rubber-based, and silicon-based pressure-sensitive adhesives can be used. From the viewpoints of transparency and durability, acrylic-based pressure-sensitive adhesives are preferable.

The pressure-sensitive adhesive may be uniformly applied in a predetermined amount on the surface to be bonded comprising the barrier layer 20, and the cover layer 16 may be placed thereon and then cured. A predetermined amount may be uniformly applied to one surface to form a pressure-sensitive adhesive coating, and the coating may be bonded to the surface to be bonded, and then cured.
Moreover, you may use the commercially available adhesive film in which the adhesive layer was previously provided for the cover layer 16. FIG.
The thickness of the adhesive layer 22 made of such a pressure-sensitive adhesive is preferably in the range of 0.1 to 100 μm, more preferably in the range of 0.5 to 50 μm, and still more preferably in the range of 10 to 30 μm.

[Other layers in the optical information recording medium 10]
The preferred optical information recording medium 10 may have other arbitrary layers in addition to the above-described layers. Examples of such other optional layers include a label layer having a desired image formed on the back surface of the substrate 12 (the back surface with respect to the formation surface of the write-once recording layer 14), the substrate 12 and the write-once recording layer 14, and the like. A light reflecting layer 18 (described later) provided between the barrier layer 20 (described later) provided between the write-once recording layer 14 and the cover layer 16, and provided between the light reflecting layer 18 and the write-once recording layer 14. And an interface layer. Here, the label layer is formed using an ultraviolet curable resin, a thermosetting resin, a heat drying resin, or the like.
Note that each of the above layers may be a single layer or may have a multilayer structure.

[Light reflecting layer 18]
In the optical information recording medium 10, a light reflecting layer 18 is formed between the substrate 12 and the write-once recording layer 14 in order to increase the reflectivity with respect to the laser light 46 and to give the function of improving the recording / reproducing characteristics. It is preferable.

The light reflecting layer 18 can be formed on the substrate 12 by vacuum deposition, sputtering or ion plating of a light reflecting material having a high reflectance with respect to the laser light 46.
The layer thickness of the light reflecting layer 18 is generally in the range of 10 to 300 nm and preferably in the range of 50 to 200 nm.
The reflectance is preferably 70% or more.

  As the material of the reflective layer, Mg, Se, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Co, Ni, Ru, Rh, Pd, Ir, Pt , Cu, Ag, Au, Zn, Cd, Al, Ga, In, Si, Ge, Te, Pb, Po, Sn, Bi, and other metals and semi-metals or stainless steel.

[Barrier layer 20 (intermediate layer)]
In the optical information recording medium 10, it is preferable to form a barrier layer 20 between the write-once recording layer 14 and the cover layer 16.
The barrier layer 20 is used for improving the storability of the write-once recording layer 14, improving the adhesion between the write-once recording layer 14 and the cover layer 16, adjusting the reflectance, adjusting the thermal conductivity, etc. Provided.

The material used for the barrier layer 20 is not particularly limited as long as it is a material that transmits light used for recording and reproduction and can express the above functions. Is a material with low permeability of gas and moisture, and is preferably a dielectric.
The barrier layer 20 can be formed by a vacuum film formation method such as vacuum deposition, DC sputtering, RF sputtering, or ion plating. Among these, it is more preferable to use sputtering, and it is more preferable to use RF sputtering.
The thickness of the barrier layer 20 is preferably in the range of 1 to 200 nm, more preferably in the range of 2 to 100 nm, and still more preferably in the range of 3 to 50 nm.

<Optical information recording method>
In the optical information recording medium 10, first, while rotating the optical information recording medium 10 at a constant linear velocity (0.5 to 10 m / second) or a constant angular velocity, the optical information recording medium 10 is used for recording semiconductor laser light or the like from the cover layer 16 side. Laser light 46 is irradiated through an objective lens 45 having a numerical aperture NA of, for example, 0.85. By the irradiation of the laser beam 46, the write-once recording layer 14 absorbs the laser beam 46 and the temperature rises locally, causing a physical or chemical change (for example, generation of pits) to change its optical characteristics. Thus, it is considered that information is recorded.

  As the recording laser beam 46, a semiconductor laser beam having an oscillation wavelength in the range of 390 to 450 nm is used. As a preferable light source, a blue-violet semiconductor laser beam having an oscillation wavelength in the range of 390 to 415 nm and an infrared semiconductor laser beam having a center oscillation wavelength of 850 nm are made a half wavelength using an optical waveguide device, and a blue-violet color having a center oscillation wavelength of 425 nm is used. SHG laser light can be mentioned. In particular, it is preferable to use a blue-violet semiconductor laser beam having an oscillation wavelength in the range of 390 to 415 nm in terms of recording density. Reproduction of information recorded as described above is performed by irradiating a semiconductor laser beam from the substrate side or the protective layer side while rotating the optical information recording medium 10 at the same constant linear velocity as described above, and detecting the reflected light. Can be done.

  As the laser light 46, a near-infrared laser light (usually a laser light having a wavelength near 780 nm), a visible laser light (630 nm to 680 nm), a laser light having a wavelength of 530 nm or less (a 405 nm blue laser), or the like is used. It is also possible to use visible laser light (630 nm to 680 nm) and laser light having a wavelength of 530 nm or less (405 nm blue laser), and in particular, laser light having a wavelength of 530 nm or less (405 nm blue laser). Preferably there is.

  Next, a stamper for manufacturing the substrate 12 of the optical information recording medium 10 as described above and a method for manufacturing a stamper original plate for manufacturing the stamper will be described.

[Method of manufacturing stamper master]
The stamper master is a mold for manufacturing a stamper, and is manufactured as follows.
In the drawings to be referred to, FIG. 4 is a diagram showing a manufacturing process of the stamper original plate.

(Resist layer formation process)
First, a silicon wafer 51 (for example, an 8-inch dummy wafer manufactured by Fujimi Fine Technology) as a silicon-containing substrate having a smooth surface is prepared. Next, a pretreatment for forming an adhesion layer on the silicon wafer 51 is performed. Then, as shown in FIG. 4A, an electron beam resist solution is applied by a method such as spin coating to form a resist layer 52 and baked. For the electron beam resist solution, FEP-171 manufactured by Fuji Film Electromaterials Co., Ltd. is used, and the film thickness can be 100 nm.

(Electron beam irradiation process)
Next, as shown in FIG. 4B, the resist layer 52 is irradiated with an electron beam modulated in accordance with various signals such as an address by an electron beam exposure apparatus having a high-precision rotary stage, and a desired pattern is formed on the resist layer 52. Draw by exposure. At this time, if the pattern to be drawn is drawn with the first exposure line 531 corresponding to the first pre-groove 34 and the second exposure line 532 corresponding to the second pre-groove 35 and thinner than the first exposure line 531. Good.

The line width by electron beam exposure is 100 to 180 nm, and more preferably 120 to 140 nm. For example, the first exposure line 531 (data area) may be drawn at 140 nm, and the second exposure line (BCA area) 532 may be drawn at 100 nm. The address recorded in the first pregroove 34 or the second pregroove 35 can be recorded by modulating the first exposure line 531 or the second exposure line 532 in a wave shape. The wave amplitude (wobble width) at this time can be 14 to 24 nm, more preferably 15 to 17 nm.
As an electron beam for drawing the first exposure line 531 and the second exposure line 532, one having an acceleration voltage of 50 kV can be used.
The first exposure line 531 and the second exposure line 532 may be lines in which dots are arranged.

(Development process)
Thereafter, as shown in FIG. 4C, the resist layer 52 is developed with a developer, and the exposed portions (first exposure line 531 and second exposure line 532) are removed. By this processing, openings 54 (541, 542) having a predetermined pattern are formed in the resist layer 52. Specifically, a first opening 541 is formed corresponding to the first exposure line 531 having a large width, and a second opening 542 is formed corresponding to the second exposure line 532 having a narrow width. Note that FHD-5 manufactured by FUJIFILM ELECTRO MATERIALS can be used as the developer.

(Etching process)
Next, as shown in FIG. 4D, an etching gas is made to collide with the silicon wafer 51 from the opening 54 of the resist layer 52 by etching, so that the silicon wafer 51 has a desired depth, for example, 30 to 50 nm, most preferably. Remove about 40 nm. In this etching, anisotropic etching is desirable in order to minimize undercutting, that is, etching in a direction perpendicular to the depth direction. As such anisotropic etching, RIE (Reactive Ion Etching) in which the etching gas has high straightness can be used.
By the etching process, a wide first groove 551 corresponding to the first opening 541 and a narrow second groove 552 corresponding to the second opening 542 are formed in the silicon wafer 51. The depths of the first groove 551 and the second groove 552 are also different depending on the size of the opening 54, and the depth a of the first groove 551 is 60 nm or less, which is deeper than the second groove 552, preferably 30 to About 50 nm, More preferably, it is 35-45 nm. The depth b of the second groove 552 is shallow and is about 5 to 30 nm, preferably 8 to 17 nm. That is, it is formed in a relationship of a> b.
The angles of the side walls of the first groove 551 and the second groove 552 are preferably in the range of 40 to 80 degrees with respect to the surface of the silicon wafer 51, and more preferably in the range of 55 to 65 degrees.
For RIE, E620 manufactured by Panasonic Factory Solutions can be used. Further, CHF ₃ can be used as an etching gas.
Further, the angle of the side wall can be controlled by a reaction product of Si and etching gas. For example, the test is performed by changing the state of the reaction product by changing the gas flow rate, pressure, or the like by using gases with different generation amounts of the reaction product, and setting the side wall of the formed groove to a desired angle.

(Resist removal process)
Next, the resist layer 52 remaining in the etching process is removed. For example, as a dry method, the resist layer 52 can be removed by irradiating oxygen plasma to remove organic substances (ashing). Note that the resist layer 52 may be removed by a wet method such as a stripping solution.
As shown in FIG. 4E, the stamper master 50 is manufactured by the above steps.
In this way, the stamper original plate 50 is formed with two types of grooves (first groove 551 and second groove 552) that are extremely fine but have different sizes with high accuracy.

[Method of manufacturing stamper]
Next, a method for manufacturing a stamper from the stamper master 50 will be described.
FIG. 5 is a diagram showing a stamper manufacturing process.

(Thin film formation process)
In order to manufacture the stamper 60 (see FIG. 5E) from the stamper master 50, the stamper master 50 is electroformed (electroplated) to make a metal plate 63 having a shape in which the surface of the stamper master 50 is inverted.
First, as shown in FIG. 5A, as a pretreatment for electroforming the stamper master 50, a metal thin film 61 having a thickness of several tens of nm, for example, about 18 nm is formed as a conductive layer by a method such as sputtering. . Thereby, conductivity is imparted to the surface of the silicon wafer 51. For example, Ni can be used as the material of the metal thin film 61.

(Plating process)
Next, the stamper original plate 50 on which the metal thin film 61 is formed is placed in, for example, a plating solution (temperature 55 ° C.) mainly composed of nickel sulfamate, and the metal is 295 ± 5 μm as shown in FIG. The electroplating layer 62 is formed by electroplating to a certain thickness. The same material as the metal thin film 61 can be used for the electroplating layer 62.

(Peeling process)
Next, as shown in FIG. 5C, the metal plate 63 composed of the metal thin film 61 and the electroplating layer 62 is peeled off from the stamper original plate 50. At the time of peeling, the stamper original plate 50 is immersed in a liquid that is substantially the same temperature as the plating solution used in the plating process, for example, within ± 5 ° C. with respect to the temperature of the plating solution, and the metal plate 63 is washed away while washing the plating solution. It is advisable to inject pure hot water between the stamper master 50 and the stamper master 50. As the liquid at this time, pure water (pure warm water) can be used.

(Punching process)
The produced metal plate 63 is punched with a press machine having an outer diameter of 138 mm and an inner diameter of 22 mm, and the inner and outer diameters are machined.

  A protective agent such as Shirotite made by Hirotec Co., Ltd. is applied to the surface of the metal plate 63 formed by machining (the surface on which the concavo-convex shape is formed) and dried, and the surface is protected as shown in FIG. A film 64 is formed.

Then, the back surface of the metal plate 63 is polished and smoothed by a rotary polishing apparatus. As for the surface roughness at this time, Ra should be about 0.5 to 1 μm.
Next, as shown in FIG. 5E, the protective film 64 is removed by ashing or the like by irradiation with oxygen plasma, whereby the stamper 60 is completed.

(Inspection process)
After the stamper 60 is completed, a cover layer similar to the cover layer 16 of the optical information recording medium 10 is attached to the surface to protect the surface, and then the groove quality of the stamper 60 is confirmed by an electrical signal inspection device.
As the electrical signal inspection apparatus, a conventionally known apparatus can be used. As inspection contents, groove reflectivity and its fluctuation, push-pull signal (wobble shape) confirmation, and address error rate by a signal detector. It is recommended to perform measurement and inspection of foreign matter with a dust inspection machine.

In this way, the stamper 60 to which the uneven shape on the surface of the stamper master 50 is transferred is formed. The stamper master 50 after the metal plate 63 is peeled off is washed with a cleaning solution such as a strong acid, and then the thin film forming step, the plating step, and the peeling step are performed to produce a plurality of stampers 60 from one original plate. can do.
Since the stamper 60 is produced by directly transferring from the stamper master 50, fine irregularities are formed with high accuracy.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention can be appropriately modified and implemented without departing from the gist of the present invention.
For example, in the embodiment, the case where two different types of uneven shapes are formed on the stamper master 50 and the stamper 60 has been described, but the present invention can also be applied to the case where three or more types of uneven shapes are formed. That is, in the case of deep and large grooves, the resist layer is irradiated with a thick beam diameter when irradiating the electron beam, and in the case of shallow and small grooves, the resist layer is irradiated with an electron beam with a thin beam diameter. For example, the depth of the groove can be adjusted.

  In the above-described embodiment, a positive resist that removes the resist layer 52 irradiated with the electron beam is used. However, a negative resist that removes the resist layer 52 that is not irradiated with the electron beam may be used. it can. Even in this case, the size of the opening formed in the resist layer 52 is changed by changing the beam diameter of the electron beam or changing the distance (pitch) between adjacent circles of the spiral drawn by the electron beam, The depth of the groove formed in the silicon wafer 51 during etching can be changed.

  For example, in the above-described embodiment, the metal thin film 61 and the electroplating layer 62 are made of the same material (nickel). However, the electroplating layer 62 may be a metal thin film as long as the adhesion to the metal thin film 61 is good. A material different from the material of 61 may be used.

It is a top view of the stamper original plate for manufacturing an optical information recording medium. It is a figure explaining groove depth. It is sectional drawing which shows the layer structure of the optical information recording medium in which the stamper original plate manufactured by the manufacturing method of this invention or a stamper is utilized. It is a figure which shows the manufacturing process of a stamper original plate. It is a figure which shows the manufacturing process of a stamper.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Optical information recording medium 34 1st pregroove 35 2nd pregroove 50 Stamper original plate 51 Silicon wafer 52 Resist layer 54 Opening 60 Stamper 61 Metal thin film 62 Electroplating layer 63 Metal plate 64 Protective film 531 1st exposure line 532 2nd Exposure line 541 First opening 542 Second opening 551 First groove 552 Second groove

Claims (15)

A resist layer forming step of forming a resist layer on the Si-containing substrate;
An electron beam irradiation step of irradiating the resist layer with an electron beam and drawing a predetermined pattern;
Developing the resist layer, and removing the portion irradiated or not irradiated with the electron beam;
Etching to perform reactive ion etching on the surface of the Si-containing substrate exposed by the development step to form a concavo-convex shape including two or more kinds of grooves having a depth of 60 nm or less and different depths on the surface of the Si-containing substrate. Process,
A method for producing a stamper master for an optical information recording medium, comprising: The two or more types of grooves having different depths include a first pregroove formed in a spiral shape, and a second pregroove formed in a spiral shape on the inner peripheral side of the first pregroup,
When the depth of the first pregroove is a and the depth of the second pregroove is b,
a> b
The method for producing a stamper master for an optical information recording medium according to claim 1, wherein:   3. The optical information recording medium stamper master according to claim 2, wherein the first pre-groove is formed as a data storage area, and the second pre-groove is formed as a management information storage area (BCA). Manufacturing method.   4. The method for manufacturing a stamper master for an optical information recording medium according to claim 2, wherein the depth a of the first pregroove is 30 to 50 nm.   5. The method for producing a stamper master for an optical information recording medium according to claim 2, wherein a depth b of the second pregroove is 5 to 30 nm. 6.   6. The method for producing a stamper original plate for an optical information recording medium according to claim 1, wherein a portion irradiated with the electron beam is removed in the developing step.   In the electron beam irradiation step, the pattern is drawn with two or more different line widths, thereby forming grooves with two or more different depths according to the line width in the etching step. The method for producing a stamper master for an optical information recording medium according to any one of claims 1 to 6. A thin film forming step of forming a conductive layer on the surface on which the concavo-convex shape of the stamper original plate for an optical information recording medium manufactured by the method according to any one of claims 1 to 7 is formed;
A plating step of forming a metal plate including the conductive layer by electroplating on the conductive layer;
A peeling step of peeling the metal plate from the stamper master for the optical information recording medium;
A punching step of punching the peeled metal plate into a predetermined shape;
A method for manufacturing a stamper for an optical information recording medium, comprising:   9. The method of manufacturing a stamper for an optical information recording medium according to claim 8, wherein after the formation of the metal plate, the metal plate is peeled in a liquid having the same temperature as the plating solution used in the plating step.   The method of manufacturing a stamper for an optical information recording medium according to claim 9, wherein the temperature of the liquid is within ± 5 ° C with respect to the temperature of the plating solution.   A protective film is applied to the surface of the metal plate punched in the punching step and dried, and then the back surface of the metal plate is polished and smoothed by a dry or wet method. A method for manufacturing a stamper for an optical information recording medium according to any one of claims 8 to 10.   12. The optical information recording medium stamper according to claim 8, further comprising an inspection step of inspecting the metal plate by an electrical signal inspection device after the plating step. 12. Method.   13. The method of manufacturing a stamper for an optical information recording medium according to claim 12, wherein a cover layer is provided on the surface of the metal plate before the inspection is performed in the inspection step.   14. The method for manufacturing a stamper for an optical information recording medium according to claim 13, wherein the cover layer is removed after the inspection step, and the surface of the metal plate is subjected to an oxygen plasma treatment.   15. The method of manufacturing an optical information recording medium stamper according to claim 8, wherein the optical information recording medium stamper is manufactured a plurality of times from one optical information recording medium stamper master. A method for manufacturing a stamper for an optical information recording medium.

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