JP4463224B2 - Convex structure base and manufacturing method thereof, master for recording medium comprising convex structure base and manufacturing method thereof - Google Patents

Description

  The present invention relates to a convex structure base having a convex structure on a support substrate that can be applied to various devices such as an optical device and a biological device, and in particular, with high accuracy at a laser beam feeding period or less in a laser exposure apparatus. The present invention relates to a convex structure base having a convex structure on a support substrate, a manufacturing method thereof, a recording medium master comprising the convex structure base, and a manufacturing method thereof.

An optical disk manufacturing master is manufactured by procedures such as photoresist exposure using a laser beam, resist patterning by development, and substrate etching using the patterned resist as a mask. In order to cope with higher density (miniaturization of the uneven pattern), electron beam exposure has been studied.
However, in the case of electron beam exposure, a reduction in throughput is inevitable because the sensitivity of the photoresist is insufficient and a vacuum process is required. In addition, the electron beam drawing apparatus is very expensive and requires an enormous initial investment. In addition, the maintenance of the apparatus is difficult and the running cost is high. As described above, in the case of electron beam exposure, the process cost increases due to a decrease in throughput, an increase in initial investment, and an increase in running cost. Under such circumstances, a method for forming a fine concavo-convex pattern (structure) with a laser beam for the purpose of cost reduction is disclosed.

For example, a thermosensitive recording layer containing at least Sb and O is formed on a substrate, and this thermosensitive recording layer is irradiated with a laser beam, utilizing the difference in etching rate between an exposed portion and an unexposed portion. A master manufacturing method for forming an uneven pattern has been proposed (see, for example, Patent Document 1).
Further, there has been proposed a fine pattern forming method in which a concave portion inducing layer made of a dielectric or metal oxide provided in a resin layer is focused and irradiated with a light beam to form pits and / or guide grooves in the resin layer. (For example, refer to Patent Document 2).
Alternatively, a resist layer containing an incomplete oxide of a transition metal such as W or Mo is formed on the substrate, and the resist layer is exposed to ultraviolet light, visible light, or laser light, and then developed to form an uneven pattern. A method of manufacturing an optical disc master to be formed has been proposed (see, for example, Patent Document 3).
Further, a method for manufacturing an optical disc stamper is proposed in which a phase change film formed on a substrate is irradiated with laser light to perform thermal recording, and this is etched to form irregularities (see, for example, Patent Document 4). .)

As described above, a method for forming a fine pattern using a thermal change of a material by laser heating has been proposed. Such a method is referred to as “heat mode lithography” in the following description.
In the case of pattern formation by heat mode lithography, a thermal reaction layer in which the material structure is changed by laser heating is provided. Since the structural change of the thermal reaction layer occurs with a threshold value with respect to temperature, a region smaller than the laser beam spot diameter can be changed. For this reason, a fine concavo-convex pattern can be formed by etching the thermal reaction layer after laser irradiation. For example, when manufacturing an optical disc master by heat mode lithography, a laser exposure apparatus for manufacturing a low-density master is used. There is an advantage that the density can be increased.

  However, the manufacturing method using the heat mode lithography proposed above has the following problems. That is, when manufacturing an optical disc master, the accuracy of the period of the structure in the radial direction of the disc, that is, the accuracy of the track pitch, depends on the laser beam feed accuracy of the laser exposure apparatus. Therefore, when manufacturing an optical disc master having a reduced track pitch using a laser exposure apparatus (for example, a laser exposure apparatus of the previous generation) with insufficient laser beam feed accuracy, sufficient track pitch accuracy cannot be ensured. There is a problem. In other words, it is necessary to devise a technique for increasing the accuracy of the track pitch. If such a problem can be solved, the laser exposure apparatus of the previous generation can be applied and the life of the apparatus can be extended, so that no capital investment is required and the process cost can be reduced.

In addition, the present applicant forms a first dielectric layer, a light absorption layer, and a second dielectric layer (for example, including silicon oxide) sequentially on the support substrate in advance or by laser beam irradiation. A method of manufacturing an optical recording medium including a step of removing an unrecorded portion of the second dielectric layer by etching and processing it into a convex shape has been proposed (see, for example, Patent Document 5).
With this proposal, it is possible to form an uneven pattern by a simple process that does not use photolithography. However, it is difficult to ensure a sufficient track pitch accuracy when a track is reduced by using a laser exposure apparatus with insufficient laser beam feeding accuracy.

JP 2005-100602 A JP 2005-71564 A JP 2004-152465 A JP-A-9-115190 JP 2005-158191 A

The present invention has been made in view of the above prior art, and has a fine and high-precision convex structure on a support substrate that is equal to or shorter than a laser beam feeding period in a laser exposure apparatus, and includes an optical device, a biological device, and the like. It is an object of the present invention to provide a convex structure base applicable to the various devices described above and a method for manufacturing the same, a recording medium master made of the convex structure base, and a method for manufacturing the same.
The laser exposure apparatus uses an apparatus with insufficient laser beam feeding accuracy (hereinafter sometimes referred to as “one-generation-preceding laser exposure apparatus”) while suppressing the increase in process cost. The goal is to achieve.

As a result of intensive studies, the present inventor has found that the above problems can be solved by the inventions described in (1) to (14) below, and has reached the present invention. However, (7) and (8) are provided as reference examples. Hereinafter, the present invention will be specifically described.

(1): On the support substrate , the convex structure is composed of a mixture of the A layer and the A layer / B layer stack, and the A layer and the A layer / B layer stack are alternately formed. A convex structure substrate,
The convex structure is
In a laminate in which a heat-changeable A layer containing silicon oxide and a heat-changeable B layer that generates heat by absorbing laser light are sequentially provided on a support substrate,
A convex structure substrate characterized by being formed by performing laser beam irradiation and etching treatment with a predetermined feed cycle, and having an interval equal to or shorter than the laser beam feed cycle.

  The convex structure substrate has a convex structure formed on a support substrate formed at intervals of a laser beam feeding cycle in a laser exposure apparatus or at a reduced interval (for example, half of the laser beam feeding cycle). Yes, it can be used as a master for recording media such as various devices and optical disks such as optical devices such as photonics crystal devices and biological devices such as biochips. In particular, it is possible to form a fine and highly accurate convex structure using a laser exposure apparatus of the previous generation, so that no capital investment is required and process costs can be reduced.

  (2): The convex structure according to (1), wherein the B layer provided on the support substrate contains a single element selected from Sb, Si, Ge, and Sn or a compound containing these elements. It is a substrate.

  By using the B layer containing the element simple substance or the compound, the heat is effectively generated by the irradiation of the laser beam to cause a thermal change at the threshold temperature. For example, the region smaller than the laser beam spot diameter is changed and this heat is changed. By etching the reaction layer, convex structures can be formed at intervals equal to or shorter than the laser beam irradiation feed period.

  (3): A state of the A layer and the B layer provided on the support substrate before laser light irradiation is all scattered when the diffraction angle in X-ray diffraction measurement using copper Kα rays is 2θ. The convex structure substrate according to (1) or (2), wherein the half-width (FWHM) of the diffraction peak is in an amorphous state showing 1.5 ° or more.

  By making each of the A layer and the B layer amorphous (noncrystalline), the residual stress of each layer (film) can be reduced. By reducing the residual stress, it is possible to form a film uniformly on a large-area support substrate, for example, a large-area substrate such as a recording medium master, without causing defects such as cracks. Further, it is preferable in heat treatment of the A layer and / or B layer by laser light irradiation, etching treatment of the thermal reaction layer, and the like because a convex structure can be formed accurately and uniformly.

(4): A recording medium master comprising the convex structure substrate according to any one of (1) to (3),
The recording medium master is characterized in that the support substrate of the convex structure base is disk-shaped, and the convex structure is spiral or concentric.

By using the convex structure base as described above, a master for a recording medium such as an optical disk is provided.
That is, the convex structure in the convex structure base can be formed with an interval equal to or shorter than the laser beam irradiation feed period in the laser exposure apparatus as described above. For this reason, for example, even when the period of the convex structure in the master disc for optical disk recording media is reduced, it is possible to compensate for and improve the lack of accuracy of the previous generation exposure apparatus with insufficient laser beam feeding accuracy. It is. Therefore, it is not necessary to update the equipment, so that the process cost can be reduced.

  (5): The convex structure is composed of a mixture of an A layer and an A layer / B layer stack, and the structures of the A layer and the A layer / B layer stack are alternately formed. And (4).

  Each laminated structure is formed by subjecting the laminated body to irradiation with a laser beam having a predetermined feeding period and etching treatment to alternately form the A layer and the A layer / B layer laminated structure to form a hybrid structure. Can be set to half (1/2) of the laser beam feeding period. Thus, it can be used as a recording medium master with high density and high accuracy.

  (6): The recording medium according to (5), wherein a difference in height from the surface of the support substrate in each of the structures of the A layer and the A layer / B layer laminate is in the range of 5 to 50 nm. This is a master disc.

  By adopting the above configuration, it is possible to stabilize the tracking by irradiating each convex structure with laser light.

(7): A method for producing a convex structure substrate having a convex structure on a support substrate,
The following process:
(A) Power adjustment having a predetermined feeding period in a laminate in which a heat-changeable A layer containing silicon oxide and a heat-changeable B layer that generates heat by absorbing laser light are sequentially provided on a support substrate Irradiating the laser beam and heating the B layer so as to spread over the entire B layer,
(B) a step of thermally changing a part of the A layer by heat conduction from the B layer;
(C) an etching step of removing the entire region of the thermally changed B layer with an etching solution 1 that dissolves only the thermally changed B layer;
(D) an etching step of removing the non-thermally changing A layer exposed on the surface with an etching solution 2 that dissolves only the non-thermally changing A layer;
Thus, a convex structure body made of only the A layer formed at intervals corresponding to the laser beam irradiation feed period is formed on the support substrate.

  As described above, it is possible to easily manufacture a convex structure base having a highly accurate convex structure having an interval corresponding to the laser beam irradiation feed period using the laser exposure apparatus of the previous generation.

(8): A method for producing a convex structure substrate having a convex structure on a support substrate,
The following process:
(E) Power adjustment having a predetermined feeding period in a laminate in which a heat-changeable A layer containing silicon oxide and a heat-changeable B layer that generates heat by absorbing laser light are sequentially provided on a support substrate Irradiating the laser beam and heating the B layer to thermally change a part of the B layer;
(F) A step of preventing the A layer from being thermally changed by suppressing the temperature rise associated with the heat conduction from the B layer by adjusting the power of the laser beam,
(G) an etching step of removing the thermally changed B layer with an etching solution 1 that dissolves only the thermally changed B layer;
(H) A laser beam irradiation feed period on the support substrate by an etching process in which the A layer whose surface is not thermally changed is removed by an etching solution 2 that dissolves only the A layer that is not thermally changed. A convex structure base body is formed by forming a convex structure composed only of an A-layer / B-layer stack formed at intervals corresponding to.

  As described above, it is possible to easily manufacture a convex structure base having a highly accurate convex structure having an interval corresponding to the laser beam irradiation feed period, using the laser exposure apparatus of the previous generation.

(9): A method for producing a convex structure substrate having a convex structure on a support substrate,
The following process:
(I) Power adjustment having a predetermined feeding period in a laminate in which a heat-changeable A layer containing silicon oxide and a heat-changeable B layer that generates heat by absorption of laser light are sequentially provided on a support substrate Irradiating the laser beam and heating the B layer to thermally change a part of the B layer;
(J) a step of thermally changing a part of the A layer by heat conduction from the B layer;
(K) an etching step of removing the thermally changed B layer with an etching solution 1 that dissolves only the thermally changed B layer;
(L) A laser beam irradiation feed period on the supporting substrate by an etching process in which the A layer whose surface is not thermally changed is removed with an etching solution 2 that dissolves only the A layer that is not thermally changed. A method of manufacturing a convex structure substrate, comprising forming a convex structure formed by mixing an A layer and an A layer / B layer stack formed at the following intervals.

  According to the above, a convex structure base having a high-density and high-precision convex structure having an interval that is half the laser beam feeding cycle can be easily manufactured using the laser exposure apparatus of the previous generation.

  (10) The method for producing a convex structure substrate according to any one of (7) to (9), wherein the etching solution 1 is an alkaline aqueous solution and the etching solution 2 is a hydrofluoric acid aqueous solution.

  When an alkaline aqueous solution is used as the etching solution 1 and a hydrofluoric acid aqueous solution is used as the etching solution 2, a structure in which only the A layer is formed on the support substrate by utilizing the thermal change of the A layer and the B layer by laser light irradiation Alternatively, any convex structure having a configuration in which only the A layer / B layer stack is formed or a configuration in which the A layer and the A layer / B layer stack are mixed can be easily formed with high accuracy.

(11): A method of manufacturing a recording medium master comprising a convex structure substrate having a spiral or concentric convex structure on a disk-shaped support substrate,
The manufacturing method is based on the manufacturing method according to any one of (7) to (9), and is a method for manufacturing a recording medium master.

  As described above, a master for a recording medium such as an optical disk having an interval equal to or shorter than the laser beam irradiation feed cycle is manufactured at low cost using a laser exposure apparatus one generation before.

  (12): The convex structure is composed of a mixture of an A layer and an A layer / B layer stack, and the structures of the A layer and the A layer / B layer stack are alternately formed. (11) is a manufacturing method of a recording medium master.

  As described above, a recording medium master with high density and high accuracy can be easily manufactured using the laser exposure apparatus of the previous generation.

(13): A method of manufacturing a recording medium master having spiral or concentric irregularities on the surface of a disk-shaped support substrate,
The following process:
(I) A laminated body in which a heat-changeable A layer containing silicon oxide and a heat-changeable B layer that generates heat by absorbing laser light are sequentially provided on a disk-shaped support substrate with a predetermined feeding period. Irradiating a laser beam having a power adjusted and heating the layer to thermally change a part of the B layer;
(J) a step of thermally changing a part of the A layer by heat conduction from the B layer;
(K) an etching step of removing the thermally changed B layer with an etching solution 1 that dissolves only the thermally changed B layer;
(L) an etching step of removing the non-thermally changing A layer exposed on the surface with an etching solution 2 that dissolves only the non-thermally changing A layer;
(M) an etching process for forming irregularities on the surface of the support substrate using the convex structure composed of the A layer and the A layer / B layer alternately formed in a spiral shape or concentric shape as described above as an etching mask;
(N) a step of completely removing the convex structure by etching to form the irregularities;
Thus, a spiral or concentric concavity and convexity formed at intervals equal to or shorter than the laser beam irradiation feed period is formed on the surface of the support substrate.

According to the above, a recording medium master having a concavo-convex shape made only of the support substrate material is manufactured.
Since the recording medium master is composed of a single material, for example, in the transfer process when creating the stamper, the convex structure is not detached or peeled off, so that the durability of the master can be increased.

  (14) The method for manufacturing a master for a recording medium according to claim 13, wherein the etching for forming the irregularities is dry etching.

  By dry etching, for example, fine and highly accurate irregularities are satisfactorily formed on the surface of an inorganic support substrate such as quartz, and the etching rate of the convex structure used as a mask is controlled in a well-balanced manner and completely removed.

The convex structure substrate of the present invention has a fine and highly accurate convex structure and can suppress the increase in cost. Therefore, optical devices such as photonic crystal devices, biological devices such as biochips, various devices, optical disks, etc. It can be used as a recording medium master.
Further, according to the method for manufacturing a convex structure substrate of the present invention, a highly accurate convex structure having an interval equal to or shorter than the laser beam irradiation feed period is applied to a laser exposure apparatus (one laser beam feed accuracy is insufficient). It can also be manufactured using a pre-generation laser exposure apparatus). For this reason, an increase in process cost can be suppressed.
Furthermore, according to the recording medium master of the present invention, a structure in which the interval between the convex structures is half the irradiation feed period of the laser beam can be obtained, so that a fine and highly accurate stamper can be formed and is inexpensive. In addition, a high-density optical disk can be easily produced.
In addition, according to the method for manufacturing a recording medium master of the present invention, a recording medium master having a highly accurate convex structure having an interval equal to or shorter than the laser beam feeding period uses a laser exposure apparatus one generation before. And cheaply. Furthermore, a recording medium master made of a single material having a convex structure as an etching mask and having irregularities on the surface of the support substrate by dry etching can be manufactured, and the durability of the master can be increased.

As described above, the convex structure base body in the present invention is such that the convex structure is a mixture of the A layer and the A layer / B layer laminate on the support substrate , and each of the A layer and the A layer / B layer laminate is provided. The structure is a convex structure substrate formed alternately ,
The convex structure is
In a laminate in which a heat-changeable A layer containing silicon oxide and a heat-changeable B layer that generates heat by absorbing laser light are sequentially provided on a support substrate,
It is formed by performing laser beam irradiation and etching treatment with a predetermined feed cycle, and is configured with an interval equal to or shorter than the laser beam irradiation feed cycle.

Here, irradiation of the record laser light as "following Interval sending period" refers to "distance corresponding to the sending period or less, (e.g., half the feed period)".

That is, the convex structure base is formed by supporting a convex structure formed with a laser beam irradiation feed period (substantially, “laser light feed period”) in a laser exposure apparatus or with a feed period interval reduced more than that. I have on top. Since it has a fine and highly accurate convex structure, it can be used as an optical device such as a photonics crystal device, a biological device such as a biochip, various devices, or a master for a recording medium such as an optical disk. In particular, a process structure can be reduced because a fine and highly accurate convex structure can be formed even if an existing laser exposure apparatus of one generation before the laser beam feeding accuracy is insufficient.
Hereinafter, the convex structure substrate of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic cross-sectional view showing a laminate in which an A layer and a B layer are sequentially provided on a support substrate in the present invention.
In FIG. 1, reference numeral 101 denotes a supporting substrate, 102 denotes a heat-changeable A layer containing silicon oxide, and 103 denotes a heat-changeable B layer that generates heat by absorbing laser light.

  As a material of the support substrate 101, glass, quartz, or the like can be used. Moreover, the board | substrate used for semiconductor manufacture, such as Si, can also be used. Also, an HDD (hard disk) substrate such as an Al substrate can be used. In addition, a resin substrate such as polycarbonate, acrylic resin, polyolefin, epoxy, vinyl ester, or pet can be used.

As the heat-changeable A layer 102 containing silicon oxide, a material containing silicon oxide is used. Here, the silicon oxide is represented by SiOx, and x is 2 or less. The A layer is preferably a mixture of SiOx and other materials.
Various materials can be used as the other materials, but an etching solution such as a hydrofluoric acid solution (hereinafter sometimes referred to as “etching solution 2”) used when the silicon oxide is etched. A material that does not dissolve is preferred.

  Moreover, it is preferable that the material can produce a sputtering target mixed with SiOx. Furthermore, a material that can be formed at room temperature by a sputtering method is preferable. As described above, a material in which the thermal change in the deposited state is in an amorphous state (amorphous state) is used for the A layer.

The amorphous state here indicates the following state.
That is, when the diffraction angle in X-ray diffraction measurement using copper Kα rays is 2θ, it indicates a state in which the full width at half maximum (FWHM) of all scattering and diffraction peaks is 1.5 ° or more. That is, the state in which the diffraction peak is broad is defined as an amorphous state. Therefore, even if it is in a crystalline state in an extremely fine region, it may be in a state where it is a fine crystal grain and a diffraction peak becomes broad when measured by an X-ray diffraction method.

  By using a material in which the film is formed in an amorphous state, the residual stress of the film can be reduced. Since the residual stress can be reduced, it can be formed with good uniformity on a large-area substrate such as a recording medium master without causing defects such as cracks.

The A layer is preferably a material that is inherently strong in crystal orientation and grows by heat treatment to increase the crystal grain size. For example, examples of the other material include ZnS, ZnSe, and CaF ₂ .
The other materials to be mixed with SiOx are not limited to ZnS, ZnSe, CaF _{2 and the} like, and various materials that satisfy the above requirements can be used.

When the mixing ratio of SiOx and other materials is represented by the mixing ratio of the sputtering target, it is preferably in the range of SiOx: 10 mol%-other materials: 90 mol% to SiOx: 40 mol%-other materials: 60 mol%.
In the above, if the SiOx content is too small, pattern formation by etching processing cannot be performed. If the SiOx content is too large, the edge roughness of the pattern increases even if the pattern can be formed.

  The thickness of the A layer is set in the range of 5 to 200 nm. If it is 5 nm or less, it is difficult to form a uniform thin film, and if it is 200 nm or more, heat is diffused and it is difficult to form a fine pattern.

  As the B layer 103, a material that absorbs laser light and generates heat is used. In addition, a material that does not dissolve in a silicon oxide etching solution (hereinafter sometimes referred to as “etching solution 1”) such as a hydrofluoric acid aqueous solution is used. A material that can be formed at room temperature by sputtering as in the case of the A layer is preferable.

And as a B layer, it is preferable to use the material whose phase state in the formed film state is an amorphous state. The amorphous state here is a state in which the half-value width (FWHM) of all scattering and diffraction peaks is 1.5 ° or more when the diffraction angle in X-ray diffraction measurement using copper Kα rays is 2θ. Point to. That is, the state in which the diffraction peak is broad is defined as an amorphous state.
Therefore, even if it is in a crystalline state in an extremely fine region, it may be in a state where it is a fine crystal grain and a diffraction peak becomes broad when measured by an X-ray diffraction method.
Similar to the A layer, by making the B layer in an amorphous state, the residual stress of the A layer (film) can be reduced, and the film is uniformly formed on a large-area support substrate without causing defects such as cracks. be able to. In addition, it is also preferable in the etching process of the thermal reaction layer formed by laser light irradiation because it is simple and can reliably form a convex structure with high accuracy.

Examples of the material used for the B layer that satisfies the above conditions include a single element selected from Sb, Si, Ge, and Sn or a compound containing these elements. For example, SbTe, GeSbTe, AgInSbTe, etc. are illustrated as a compound containing Sb.
In addition, it is not limited to the element simple substance of the illustration, or the compound containing those elements, What kind of material can be used if it is the material which satisfies the said requirements.

  By using the B layer containing the element simple substance or the compound, the heat is effectively generated by the irradiation of the laser beam to cause a thermal change at the threshold temperature. For example, the region smaller than the laser beam spot diameter is changed and this heat is changed. By etching the reaction layer, convex structures can be formed at intervals equal to or shorter than the laser beam irradiation feed period.

  The film thickness of the B layer is set in the range of 5 nm to 100 nm. If it is 5 nm or less, it is difficult to form a uniform thin film, and if it is 100 nm or more, heat diffuses and it is difficult to form a fine pattern.

If the support substrate in the convex structure base is disk-shaped and the convex structure is spiral or concentric, it can be suitably used as a master for a recording medium such as an optical disk.
Here, if the convex structure has a structure in which the A layer and the A layer / B layer stack are alternately formed, the interval is less than or equal to the laser beam feeding period (half the laser beam feeding period). Therefore, a high density recording medium master can be obtained. Therefore, even when the period of the convex structure in the master disc for optical disk recording media is reduced, it is possible to use a one-generation previous exposure apparatus with insufficient laser beam feeding accuracy, thereby suppressing an increase in process cost. can do.

When the height difference from the surface of the support substrate in each of the structures of the A layer and the A layer / B layer stack is set to a range of 5 to 50 nm, the tracking is performed by irradiating the convex structure with laser light. Can be stabilized.
That is, when a recording medium master is irradiated with a laser beam and the laser beam is tracked with respect to the structure, if the difference in the height of the structure is less than 5 nm, the tracking error signal is lowered and the tracking is unstable. become. On the other hand, when the difference in height between the structures is higher than 50 nm, the amount of reflected light decreases due to an increase in diffracted light by the structures.

  If a stamper is made of Ni or the like using the recording medium master of the present invention, and this is used as a mold and transferred to a resin, a high-density and high-precision optical recording medium (optical disk) can be produced at low cost. Examples of the resin include polycarbonate, acrylic resin, polyolefin, epoxy resin, vinyl ester resin, and ultraviolet curable resin. Examples of the transfer (replication) method include a compression molding method, an injection molding method, and a photocuring method ( 2P transfer method) is applied.

Next, the manufacturing method of the convex structure base | substrate which has a convex structure on the support substrate in this invention is demonstrated. In other words, on the support substrate, each of the convex structure bases having a convex structure having a configuration of only the A layer, a configuration of only the A layer / B layer lamination, or a configuration in which the A layer and the A layer / B layer lamination are mixed. This will be described with reference to the drawings. However, a convex structure base body having a convex structure having a structure of only the A layer or a structure of only the A layer / B layer stack on the supporting substrate is used as a reference example.

[Method for Producing Convex Structure Base Consisting of A Layer Only]
A method for manufacturing a convex structure base body that forms a convex structure consisting only of the A layer is manufactured according to the schematic process diagram shown in FIG.
In FIG. 2, the code | symbol 200 shows a laminated body. 201 indicates a support substrate, 202 indicates an A layer, and 203 indicates a B layer.
That is, by the following process, a convex structure composed of only the A layer formed at intervals corresponding to the laser beam irradiation feed period is formed on the support substrate.
(A) Power adjustment having a predetermined feeding period in a laminate in which a heat-changeable A layer containing silicon oxide and a heat-changeable B layer that generates heat by absorbing laser light are sequentially provided on a support substrate (B) a step of thermally changing a part of the A layer by heat conduction from the B layer (c) a thermal change Etching step of removing the entire B layer with the etching solution 1 that dissolves only the thermally changed B layer (d) Dissolving the non-thermally changing A layer with the exposed surface only the A layer that has not been thermally changed Etching process to remove with etchant 2

Reference numeral 204 in the steps (a) and (b) indicates the direction of laser light irradiation. Reference numeral 205 denotes a portion where the B layer is thermally changed. That is, the B layer generates heat due to absorption of the laser light and changes heat. In the case of forming a structure with a narrow pitch, if the interval between the laser light irradiation points is narrowed, the entire area of the B layer is thermally changed by heat conduction in the B layer as shown in FIG.
Reference numeral 206 denotes a thermally changed portion of the material A layer. Part of the A layer undergoes thermal change due to heat conduction from the B layer. Reference numeral 207 denotes a portion of the A layer that is not thermally changed.
Next, in the etching step (c), an alkaline aqueous solution that dissolves only the B layer that has been thermally changed is used as the etching solution 1. That is, since the B layer thermally changed by laser heating is made of a material whose etching resistance to the alkaline aqueous solution becomes weak, the thermally changed B layer whole area 205 is removed. In the layer A, the portion 206 that has undergone thermal change and the portion 207 that has not undergone thermal change remain without being etched. As the alkaline aqueous solution, a sodium hydroxide aqueous solution (NaOH + H ₂ O) or a potassium hydroxide aqueous solution (KOH + H ₂ O) can be used.
Next, in the etching step (d), an aqueous hydrofluoric acid solution (HF + H ₂ O) that dissolves only the A layer that is not thermally changed is used as the etching solution 2. That is, since the A layer thermally changed by the heat conduction from the B layer is a material having high etching resistance to the hydrofluoric acid aqueous solution, the non-thermally changed portion 207 of the A layer that is not thermally changed is removed.
In addition, in order to advance an etching process (c) and an etching process (d) continuously, alkaline aqueous solution and hydrofluoric acid aqueous solution can also be used together.

  The following Table 1 shows the etching resistance to each etching solution 1 (alkaline aqueous solution) and etching solution 2 (etching solution 2) after each film formation of the A layer and B layer (before heat change) and after heat change by laser heating. Show. “Strong” in the table indicates that etching is difficult, and “weak” indicates that etching is easy.

That is, the heat-changeable A layer containing silicon oxide has high etching resistance to an alkaline aqueous solution. With respect to a hydrofluoric acid aqueous solution, the etching resistance is weak in a film formation state (before heat change), and the etching resistance is strong in a state where heat is changed by laser irradiation. On the other hand, the heat-changeable B layer that generates heat by absorbing laser light has a strong etching resistance to a hydrofluoric acid aqueous solution. With respect to an alkaline aqueous solution, the etching resistance is strong in a film formation state (before heat change), and the etching resistance is weak in a state where heat is changed by laser irradiation.
Through the steps (a) to (d), a convex structure composed only of the A layer is formed.

  A semiconductor laser is used as the laser light source. The wavelength of the semiconductor laser is usually 370 to 780 nm, preferably 390 to 410 nm. For example, a GaN based semiconductor laser is used. By using a semiconductor laser, an inexpensive exposure apparatus can be obtained, and the process cost can be reduced. In the case of a semiconductor laser, the power level of laser light can be modulated at high speed, so that a convex structure can be formed at a high speed with respect to a large-area laminate.

Furthermore, since a minute laser spot can be formed by using a short wavelength laser and a fine structure can be formed, even if a shorter wavelength laser light source having a wavelength of about 240 to 270 nm is used. Good.
For example, a short wavelength laser light source using a solid laser and SHG (second harmonic) or a short wavelength laser light source using the semiconductor laser and SHG can be used. By using a short wavelength laser in the ultraviolet region, a finer structure can be formed.

As shown in FIG. 2, the laser beam is irradiated from the B layer 203 side which is the uppermost layer of the laminate. That is, the B layer 203 film surface is directly irradiated without passing through the support substrate 201. In the following description, “film surface incidence” is described. By making the film surface incident, it is possible to suppress the occurrence of aberration by the support substrate.
Further, by increasing the numerical aperture (NA) of the objective lens of the laser beam irradiation optical system, the laser beam can be condensed and a finer structure can be formed. The numerical aperture (NA) of the objective lens used in the optical system is 0.5 to 1.0, preferably 0.8 to 0.95.

  When irradiating the laser beam, the laminate (medium) may be rotated. While rotating the medium, the laser beam may be irradiated while applying focus servo to the medium. Further, the laser beam may be irradiated while applying focus servo and tracking servo to the medium while rotating the medium.

[Producing method of convex structure substrate comprising only layer A / layer B]
A method of manufacturing a convex structure base body that forms a convex structure composed of only the A-layer / B-layer stack is manufactured according to the schematic process diagram shown in FIG.
In FIG. 3, the code | symbol 300 shows a laminated body. Reference numeral 301 denotes a support substrate, 302 denotes an A layer, and 303 denotes a B layer.
That is, by the following steps, a convex structure composed of only the A layer / B layer stack formed at intervals corresponding to the laser beam irradiation feed period is formed on the support substrate.
(E) Power adjustment having a predetermined feeding period in a laminate in which a heat-changeable A layer containing silicon oxide and a heat-changeable B layer that generates heat by absorbing laser light are sequentially provided on a support substrate A step of irradiating the laser beam and heating the B layer to thermally change a part of the B layer. (F) A temperature increase caused by heat conduction from the B layer is suppressed by adjusting the power of the laser beam. (G) An etching step in which the thermally changed B layer is removed with an etching solution 1 that dissolves only the thermally changed B layer. (H) The non-thermally changed A layer whose surface has been exposed, Etching process which removes with etching liquid 2 which dissolves only A layer which has not changed heat

Reference numeral 304 in the steps (e) and (f) indicates the direction of laser light irradiation. Reference numeral 305 denotes a portion where the B layer is thermally changed. Reference numeral 306 denotes a portion where the B layer is not thermally changed. The irradiation power of the laser light is set lower than the level in FIG. 2 so that the A layer does not change heat due to heat conduction from the B layer. That is, the layer B is irradiated with a laser power level at which the temperature rise of the layer A due to heat conduction from the layer B does not reach the threshold temperature causing the thermal change of the layer A. Reference numeral 305 denotes a portion where the B layer is thermally changed. Reference numeral 306 denotes a portion where the B layer is not thermally changed. Reference numeral 307 denotes a portion of the A layer that is not thermally changed.
Next, in the etching step (g), an alkaline aqueous solution that dissolves only the thermally changed layer B is used as the etching solution 1. As shown in Table 1, since the B layer thermally changed by the laser heating has a weak etching resistance to the alkaline aqueous solution, the thermally changed B layer 305 is removed, and the 306 not thermally changed remains. In addition, the A layer 307 that has not been thermally changed remains without being etched.
Next, in the etching step (h), a hydrofluoric acid aqueous solution (HF + H ₂ O) that dissolves only the A layer that is not thermally changed is used as the etching solution 2. As shown in Table 1 above, the portion 307 of the layer A where the surface is not thermally changed is removed by the hydrofluoric acid aqueous solution. In the layer 308 covered with the portion 306 where the B layer is not thermally changed, 306 serves as an etching mask, and the lower A layer 308 remains.
Through the steps (e) to (f), a convex structure composed only of the A layer / B layer stack is formed.

[Production method of convex structure substrate comprising A layer and A layer / B layer laminate]
The manufacturing method of the convex structure base body which forms the convex structure body which consists of A layer, A layer, and B layer lamination | stacking is manufactured according to the schematic process drawing shown in FIG.
In FIG. 4, the code | symbol 400 shows a laminated body. Reference numeral 401 denotes a support substrate, 402 denotes an A layer, and 403 denotes a B layer.
That is, a convex structure formed by alternately mixing the A layer and the A layer / B layer stack is formed by the following steps.
(I) Power adjustment having a predetermined feeding period in a laminate in which a heat-changeable A layer containing silicon oxide and a heat-changeable B layer that generates heat by absorption of laser light are sequentially provided on a support substrate (J) a step of thermally changing a part of the B layer by heat conduction from the B layer (k) a step of thermally changing B Etching step for removing the layer with an etching solution 1 that dissolves only the heat-changed B layer (l) An etching solution that dissolves only the A layer that has not been heat-changed and the A layer that has not been subjected to heat-change. Etching process removed by 2

Reference numeral 404 in the steps (i) and (j) indicates the direction of laser light irradiation. Reference numeral 405 denotes a laser beam feeding period. Reference numeral 406 denotes a portion where the B layer is thermally changed, and reference numeral 407 denotes a portion where the B layer is not thermally changed. Reference numeral 408 denotes a portion where the A layer is thermally changed by heat conduction from the B layer, and 409 denotes a portion where the A layer is not thermally changed.
Next, in the etching step (k), an alkaline aqueous solution that dissolves only the B layer that has been thermally changed is used as the etching solution 1. As shown in Table 1, since the B layer thermally changed by the laser heating has a weak etching resistance to the alkaline aqueous solution, the thermally changed B layer 406 is removed, and the 407 not thermally changed remains. Further, the portion 408 of the A layer that has undergone thermal change and the portion 409 of the A layer that has not undergone thermal change remain without being etched.
Next, in the etching step (l), an aqueous hydrofluoric acid solution (HF + H ₂ O) that dissolves only the A layer that is not thermally changed is used as the etching solution 2. As shown in Table 1, the portion 410 where the surface of the portion 409 of the A layer where the heat does not change is exposed by the hydrofluoric acid aqueous solution. In 409 covered with the portion 407 where the B layer is not thermally changed, 407 serves as an etching mask, and the lower A layer 409 remains.
By the above steps (i) to (l), a convex structure having a length equal to or shorter than the laser light feed period (half of the feed period) composed of a mixture of the A layer and the A layer / B layer stack is formed.

In any one of the above methods for producing a convex structure base, a recording medium master can be formed by using a support substrate as a disk-shaped substrate and a convex structure in a spiral or concentric shape. That is, the manufacturing method of the convex structure substrate can be suitably applied as a manufacturing method of a recording medium master.
In particular, according to the manufacturing method of the master for recording medium in which the A layer and the A layer / B layer lamination are alternately mixed, the convex structure having an interval equal to or shorter than the laser beam feeding period (half of the feeding period) (Track pitch in the recording medium)) is formed. Therefore, it is possible to manufacture a recording medium master such as an optical disk with high density and high accuracy at low cost by using a laser exposure apparatus (for example, a laser exposure apparatus one generation before) in which the laser beam feeding period is not sufficient. is there.

In FIG. 4L, reference numeral 412 denotes the height of the structure composed of the A layer from the surface of the support substrate 401, and 413 denotes the height of the structure composed of the A layer / B layer stack from the surface of the support substrate 401. It shows. The difference in height is preferably in the range of 5 to 50 nm. That is, the structure composed of the A layer / B layer stack is higher than the structure composed of the A layer by the amount of the B layer.
As described above, by setting the height difference in the range of 5 to 50 nm, it is possible to stabilize the tracking by irradiating each convex structure of the recording medium master disk with laser light. If the difference in height between the structures is less than 5 nm, the track error signal is lowered and tracking becomes unstable. On the other hand, when the difference in height between the structures is higher than 50 nm, the amount of reflected light decreases due to an increase in diffracted light by the structures.
In the step of manufacturing a laminate in which a heat-changeable A layer containing silicon oxide and a heat-changeable B layer that generates heat by absorption of laser light are sequentially formed on a support substrate, the thickness of the B layer is set to 5 By setting the thickness within the range of ˜50 nm, it is possible to easily produce a recording medium master having a structure with a predetermined height.

[Method for producing master for recording medium using convex structure as mask]
A recording medium master having spiral or concentric irregularities on the surface of a disk-shaped support substrate is manufactured according to a schematic process diagram shown in FIG. (FIG. 5 is a schematic process diagram for producing a recording medium master having spiral or concentric irregularities on the surface of a disk-shaped support substrate.)
In FIG. 5, reference numeral 500 indicates a disk-shaped support substrate having a convex structure in which A layers and A layers and B layers are alternately formed. The convex structure is formed in a spiral shape or a concentric shape.
That is, the convex structure 500 is formed by the following steps (i) to (l) (similar to the steps shown in FIG. 4).
(I) Power adjustment having a predetermined feeding period in a laminate in which a heat-changeable A layer containing silicon oxide and a heat-changeable B layer that generates heat by absorption of laser light are sequentially provided on a support substrate (J) a step of thermally changing a part of the B layer by heat conduction from the B layer (k) a step of thermally changing B Etching step for removing the layer with an etching solution 1 that dissolves only the heat-changed B layer (l) An etching solution that dissolves only the A layer that has not been heat-changed and the A layer that has not been subjected to heat-change. Etching process removed by 2

  In FIG. 5, reference numeral 501 denotes a disk-shaped support substrate, 502 denotes a portion where the A layer is thermally changed by heat conduction from the B layer, 503 denotes an unchanged portion of the A layer, and 504 denotes a portion where the B layer does not change heat. , 505 shows a laminated structure of an A layer 503 that does not change heat and a B layer 504 that does not change heat.

In the next step (m), the supporting substrate is formed using the convex structure composed of the A layer and the A layer / B layer alternately formed spirally or concentrically by the above (i) to (l) as an etching mask. 501 is a dry etching process for forming irregularities on the surface. The step (m) is a step in the middle of dry etching, and the disk-shaped support substrate 501 is etched and the convex structure is gradually etched.
In the step (n), the etching is stopped when the structures 502 and 505 used as an etching mask are completely removed and no longer exist. Therefore, the convex structure is completely removed by etching, and only the disk-shaped support substrate 501 having spiral or concentric irregularities is obtained. Here, it is preferable that the etching for forming irregularities on the surface of the support substrate is dry etching.

As an etching method in the steps (m) and (n), a dry etching method can be preferably used. As such a dry etching method, an RIE method (Reactive Ion Etching), an ICP method (Inductively Coupled Plasma), a sputter etching method, or the like can be used.
According to dry etching, the etching rate of a convex structure used as a mask and the etching rate of an inorganic support substrate such as quartz can be controlled in a well-balanced manner. Can be formed.

  Through the steps (i) to (n), a recording medium master having spiral or concentric concavities and convexities formed on the support substrate surface with an interval equal to or shorter than the laser beam irradiation feed period is formed. Since such a recording medium master is composed of only the support substrate material, the structure body is not detached or peeled off in the transfer process, so that the master can be used repeatedly.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by these examples.
In order to produce the recording medium masters of Example 1 and Example 2, first, laminates each having an A layer and a B layer having the structure shown in FIG. 1 were sequentially produced.
As the support substrate 101, a disk-shaped quartz substrate having a thickness of 0.5 mm was used.
As the thermally changeable A layer 102 containing silicon oxide, ZnS—SiO ₂ having a thickness of 40 nm formed by a sputtering method was used. The composition of the sputtering target is ZnS (80 mol%)-SiO ₂ (20 mol%). Film formation was performed under the conditions of film formation temperature: room temperature, RF power: 1.5 kW, film formation atmosphere: argon (Ar). As a result of measuring the deposited ZnS—SiO ₂ film by an X-ray diffraction method using copper Kα rays, the half-value width (FWHM) of the diffraction peak was 4 °, indicating that the film was in an amorphous state.
As the thermally changeable B layer 103 that generates heat by absorbing laser light, AgInSbTe with a thickness of 20 nm formed by sputtering was used. The composition of the sputtering target is Ag (4 at%)-In (7 at%)-Sb (61 at%)-Te (28 at%). Film formation temperature: room temperature, RF power: 300 W, film formation atmosphere: Ar was formed under the conditions of Ar. As a result of measuring the formed AgInSbTe film by the X-ray diffraction method using copper Kα rays, it was shown to be in an amorphous state.

Example 1
Using the above laminate, a recording medium master was produced by the method for manufacturing a recording medium master in accordance with the process shown in FIG.
That is, in the laser irradiation steps of steps (i) and (j), the laser beam 404 is directly irradiated from the B layer 403 (AgInSbTe) side. The numerical aperture of the objective lens in the optical system of the laser beam 404 is 0.85, and the wavelength of the laser beam is 405 nm. The feed period (405) of the laser beam in the radial direction is 320 nm. The laser power level was 3 mW, and a certain level of power was irradiated.

Reference numeral 406 denotes a portion where the B layer is thermally changed by laser irradiation (thermally changed AgInSbTe), and 407 denotes an unchanged portion of the B layer and AgInSbTe which does not change thermally. Reference numeral 408 denotes a portion where the A layer is thermally changed by heat conduction from the B layer (thermally changed ZnS—SiO ₂ ), and 409 denotes an unchanged portion of the A layer, which is ZnS—SiO ₂ which is not thermally changed.

Next, in the step (k) which is the first etching step, an alkaline aqueous solution, that is, an aqueous sodium hydroxide solution (NaOH + H ₂ O) was used as the etching solution 1. The solution ratio is [NaOH]: [H ₂ O] = 1: 2. The laminate subjected to the laser light irradiation treatment with an aqueous sodium hydroxide solution was etched for 5 minutes.
B layer 406 (thermally changed AgInSbTe) was removed by etching with an aqueous sodium hydroxide solution, and B layer 407 (thermally unchanged AgInSbTe) remained. In addition, the A layer 408 (ZnS—SiO ₂ thermally changed) and the A layer 409 (ZnS—SiO ₂ not thermally changed) remained without being etched.

Next, in the step (l) as the second etching step, a hydrofluoric acid aqueous solution (HF + H ₂ O) was used as the etching solution 2. The solution ratio is [HF]: [H ₂ O] = 1: 20. The laminated body which passed through the said 1st etching process was etched for 10 second with hydrofluoric acid aqueous solution.
Etching with a hydrofluoric acid aqueous solution removed the portion 410 where the surface of the A layer 409 (ZnS—SiO ₂ which does not change heat) was exposed. In the A layer 409 covered with the B layer 407 (AgInSbTe which does not change heat), the B layer 407 serves as an etching mask, the lower A layer 409 remains, and a structure having a stacked structure of 407 and 409 is formed.
Reference numeral 411 denotes the period of each structure of the A layer and the A layer / B layer stack in the radial direction, that is, the track pitch is 160 nm. Since the feed period (405) of the laser beam in the radial direction is 320 nm, the track pitch is half of the feed cycle 405 of the laser beam.
Further, the height (412) of the A layer 408 (thermally changed ZnS—SiO ₂ ) from the surface of the quartz substrate 401 was 40 nm. On the other hand, the height (413) from the surface of the quartz substrate of the laminated structure composed of the B layer 407 (AgInSbTe that does not change thermally) and the lower A layer 409 ((ZnS—SiO ₂ that does not change thermally)) was 60 nm. The difference in height between the adjacent A layer and each structure of the A layer / B layer stack is 20 nm, which is different by the film thickness of the B layer 407 (AgInSbTe that does not thermally change).

  The recording medium master produced as described above was irradiated with laser light, and the generation state of the tracking error signal was examined. The wavelength of the laser beam used is 405 nm, the numerical aperture of the objective lens is 0.85, and the laser power is 0.2 mW.

  As a result of the evaluation, the laser beam could be tracked with respect to the structure, and a good push-pull signal could be observed. That is, since it is a highly accurate convex structure and there is a difference in height of 20 nm between adjacent structures, it was possible to track even at a narrow track pitch (high density) of 160 nm.

(Example 2)
Using the laminate, a recording medium master was produced by a method for producing a recording medium master in accordance with the process shown in FIG.
That is, the recording medium master 500 in which the A layer and the A layer / B layer stack are alternately mixed in a spiral shape is obtained by the steps shown in the first embodiment.
In the next step (m), irregularities were formed on the surface of the support substrate 501 by etching using the convex structure formed on the recording medium master 500 as an etching mask. The etching process was performed by sputter etching. The etching atmosphere was Ar, and the RF power was 1 kW. Etching was completed when the structure was completely etched away as shown in step (n) of FIG.
As described above, a recording medium master having only a disk-shaped support substrate 501 having spiral irregularities was formed. The height difference 506 between the convex portions adjacent in the radial direction was 10 nm.

  The recording medium master produced as described above was irradiated with laser light in the same manner as in Example 1 to examine the occurrence state of the tracking error signal. The wavelength of the laser beam used is 405 nm, the numerical aperture of the objective lens is 0.85, and the laser power is 0.2 mW.

  As a result of the evaluation, the laser beam could be tracked with respect to the structure, and a good push-pull signal could be observed. That is, since it is a highly accurate convex structure and there is a difference in height of 10 nm between adjacent structures, tracking was possible even at a narrow track pitch (high density) of 160 nm.

  As can be seen from the above-described embodiments, the manufacturing method of the present invention can be used for a recording medium composed of a fine and high-precision convex structure substrate that is equal to or shorter than the laser beam feed cycle even if an apparatus with insufficient laser beam feed accuracy is used. The master is obtained. Since the laser exposure apparatus of the previous generation can be applied, an increase in process cost can be suppressed. The fine and highly accurate convex structure substrate of the present invention can also be applied to various devices such as optical devices and biological devices.

It is a schematic sectional drawing which shows the laminated body by which A layer and B layer were sequentially provided on the support substrate in this invention. It is a general | schematic process figure for manufacturing the convex structure base | substrate which consists only of A layer on a support substrate. It is a schematic process diagram for manufacturing a convex structure base composed of only an A layer / B layer laminate on a support substrate. It is a general | schematic process drawing for manufacturing the convex structure base | substrate which consists of A layer and A layer and B layer lamination | stacking on a support substrate. It is a schematic process diagram for manufacturing a recording medium master having spiral or concentric irregularities on the surface of a disk-shaped support substrate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Laminated body 101 Support substrate 102 Thermally changeable A layer containing silicon oxide 103 Thermally changeable B layer generated by absorption of laser light 200 Laminated body 201 Support substrate 202 A layer 203 B layer 204 Laser light irradiation Direction 205 A portion where the B layer is thermally changed 206 A portion where the material A is thermally changed 207 A portion where the A layer is not thermally changed 300 Laminated body 301 Support substrate 302 A layer 303 B layer 304 Laser beam irradiation direction 305 B layer is Thermally changed portion 306 B layer is not thermally changed 307 A layer is not thermally changed 308 Portion covered by 306 400 Laminated body 401 Support substrate 402 A layer 403 B layer 404 Laser light irradiation direction 405 Laser light feed period 406 Portion where the B layer is thermally changed 407 Portion where the B layer is not thermally changed 40 8 A part where the A layer is thermally changed by heat conduction from the B layer 409 A part where the heat of the A layer is not changed 410 A part where the surface of the 409 is exposed 411 Track pitch 412 Height of the A layer 408 from the surface of the quartz substrate 413 Height from the surface of the quartz substrate of the laminated structure composed of the B layer 407 and the A layer 409 500 Disc-shaped support substrate in which A layers and A layers and B layers are alternately formed 501 Disc-shaped support substrate 502 From the B layer Part 503 where the A layer is thermally changed due to thermal conduction of 503 Part where the A layer is not thermally changed 504 Part where the B layer is not thermally changed 505 A layer 503 which is not thermally changed and B layer 504 which is not thermally changed Laminated structure 506 Difference in height between adjacent convex parts in the radial direction

Claims (12)

Convex structure base body in which convex structure is composed of A layer and A layer / B layer stack, and each structure of A layer and A layer / B layer stack is alternately formed on a support substrate The convex structure is a laminate in which a heat-changeable A layer containing silicon oxide and a heat-changeable B layer that generates heat by absorbing laser light are sequentially provided on a support substrate. A convex structure substrate formed by performing laser beam irradiation and etching treatment with a predetermined feed period and having an interval equal to or shorter than the laser beam irradiation feed period.   2. The convex structure base according to claim 1, wherein the B layer provided on the support substrate contains a single element selected from Sb, Si, Ge, and Sn or a compound containing these elements.   The state of the A layer and the B layer provided on the support substrate before laser light irradiation is as follows. When the diffraction angle in X-ray diffraction measurement using copper Kα rays is 2θ, all scattering and half of the diffraction peaks are obtained. The convex structure substrate according to claim 1 or 2, wherein the convex structure substrate is in an amorphous state in which a value width (FWHM) is 1.5 ° or more.   A recording medium master comprising the convex structure base according to any one of claims 1 to 3, wherein a support substrate of the convex structure base has a disk shape, and the convex structure has a spiral shape or a concentric shape. A recording medium master.   The convex structure is composed of a mixture of an A layer and an A layer / B layer stack, and the structures of the A layer and the A layer / B layer stack are alternately formed. 4. A recording medium master according to 4.   6. The master for recording medium according to claim 5, wherein a difference in height from the surface of the support substrate in each of the structures of the A layer and the A layer / B layer stack is in the range of 5 to 50 nm. A method for producing a convex structure substrate having a convex structure on a support substrate,
The following process:
(I) Power adjustment having a predetermined feeding period in a laminate in which a heat-changeable A layer containing silicon oxide and a heat-changeable B layer that generates heat by absorption of laser light are sequentially provided on a support substrate Irradiating the laser beam and heating the B layer to thermally change a part of the B layer;
(J) a step of thermally changing a part of the A layer by heat conduction from the B layer;
(K) an etching step of removing the thermally changed B layer with an etching solution 1 that dissolves only the thermally changed B layer;
(L) A laser beam irradiation feed period on the supporting substrate by an etching process in which the A layer whose surface is not thermally changed is removed with an etching solution 2 that dissolves only the A layer that is not thermally changed. A method for producing a convex structure substrate, comprising forming a convex structure formed by mixing an A layer and an A layer / B layer stack composed of the following intervals. The method for producing a convex structure substrate according to claim 7, wherein the etching solution 1 is an alkaline aqueous solution and the etching solution 2 is a hydrofluoric acid aqueous solution. A method for producing a master for a recording medium comprising a convex structure substrate having a convex structure that is spiral or concentric on a disk-shaped support substrate,
A manufacturing method of a master for recording medium, wherein the manufacturing method is based on the manufacturing method according to claim 7 . The convex structure is composed of a mixture of an A layer and an A layer / B layer stack, and the structures of the A layer and the A layer / B layer stack are alternately formed. A method for producing a recording medium master according to claim 9 . A method for producing a recording medium master having spiral or concentric irregularities on the surface of a disk-shaped support substrate,
The following process:
(I) A laminated body in which a heat-changeable A layer containing silicon oxide and a heat-changeable B layer that generates heat by absorbing laser light are sequentially provided on a disk-shaped support substrate with a predetermined feeding period. Irradiating a laser beam having a power adjusted and heating the layer to thermally change a part of the B layer;
(J) a step of thermally changing a part of the A layer by heat conduction from the B layer;
(K) an etching step of removing the thermally changed B layer with an etching solution 1 that dissolves only the thermally changed B layer;
(L) an etching step of removing the non-thermally changing A layer exposed on the surface with an etching solution 2 that dissolves only the non-thermally changing A layer;
(M) an etching process for forming irregularities on the surface of the support substrate using the convex structure composed of the A layer and the A layer / B layer alternately formed in a spiral shape or concentric shape as described above as an etching mask;
(N) a step of completely removing the convex structure by etching to form the irregularities;
Thus, a spiral or concentric concavity and convexity formed at intervals equal to or shorter than the laser beam irradiation feed period is formed on the surface of the support substrate. 12. The method for manufacturing a master for recording medium according to claim 11 , wherein the etching for forming the unevenness is dry etching.

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