JP4581047B2 - Pattern forming material, pattern forming method, and optical disc - Google Patents

Description

  The present invention relates to a pattern forming material, a pattern forming method, and an optical disc using the pattern forming method, and more particularly to a pattern forming material capable of forming a fine pattern, a pattern forming method, and an optical disc using the pattern forming method.

  In recent years, optical discs such as DVDs (Digital Versatile Disks) have become widespread as high-density information recording media for recording video information and computer data. In particular, read-only optical discs (e.g., DVD-ROMs) pre-recorded with movies and computer programs are increasingly used on a daily basis as a means for easily distributing large amounts of information.

  Such a read-only optical disc has a fine pattern called a pit indicating information to be stored. Such a fine pattern formed on the optical disc is formed by transferring the patterning of the master disc of the optical disc.

  For example, an optical disc master is created by forming a pattern on a pattern forming material on a substrate to be processed using, for example, a lithography method. Next, an intermediate called a stamper is formed to which the master pattern is transferred, and the stamper pattern is transferred to produce an optical disc on which pits are formed.

  In the optical disk formed in this way, there is a method for reducing the shape of pits formed on the optical disk in order to increase the recording capacity. As described above, the pit shape of the optical disc is a transfer of the fine pattern of the master disc of the optical disc. To increase the recording capacity, the fine pattern formed on the master disc is made smaller and further miniaturized. It is preferable to do.

  For this reason, in the lithography method used for pattern formation of the master, various methods for miniaturizing the pattern to be formed have been proposed.

For example, the limit of the width of patterning that can be miniaturized by a conventional lithography method is sometimes called a so-called diffraction limit. For example, the diffraction limit D is expressed by the following formula.
D = λ / (2 × NA) (Formula 1)
In this case, the wavelength of the light source used for lithography is λ, and the numerical aperture of the objective lens is NA. That is, in order to reduce the diffraction limit D and form fine pits, the above formula 1 preferably uses a light source with a short wavelength and preferably has a large numerical aperture of the objective lens of the light source. Show.

  However, light sources with short wavelengths and optical systems with light sources with short wavelengths are often expensive, and depending on the wavelength, it is necessary to use them in a reduced pressure state. . In addition, if the numerical aperture is increased, the depth of focus becomes shallower, so that there is a concern that the patterning shape may not be able to cope with slight fluctuations in the processing target, and the lithography equipment needs to be reviewed, increasing the cost of optical disc production. There is a problem that leads to

  In addition, in the lithography method using an electron beam, although a fine pattern can be formed, it is necessary to accelerate and deflect electrons in a vacuum, and the equipment becomes expensive.

  On the other hand, the light in the visible range is inexpensive, and an inexpensive optical system generally used can be used. For this reason, a method of forming a fine pattern below the diffraction limit using active light in the visible range has been proposed (see, for example, Non-Patent Document 1).

  Non-Patent Document 1 describes a pattern forming material for forming a fine pattern. A pattern forming material including a first reaction layer and a second reaction layer formed on a substrate is irradiated with a laser. It is disclosed that a fine pattern is formed because the volume is expanded by reacting by heating.

  FIG. 1 schematically shows a pattern forming material disclosed in Non-Patent Document 1.

Referring to FIG. 1, the pattern forming material shown in figure, for example, on a substrate 400 made of silicon oxide (SiO _2), for example, zinc oxide, silicon sulfide (ZnS-SiO _2), the first reaction A layer 100 and a first reaction layer 300 are formed, and a second reaction layer made of, for example, terbium iron cobalt (TbFeCo) is formed and configured so as to be sandwiched between the two first reaction layers.

  In order to form a fine pattern using the pattern forming material thus configured, the temperature of the first reaction layer or the second reaction layer is increased by irradiating active light, for example, laser light, By reacting the first reaction layer and the second reaction layer, the volume is expanded and a fine pattern is formed.

In this case, the pattern is formed by irradiating the laser so that the temperature region that reaches the threshold at which the first reaction layer and the second reaction layer react with each other is smaller than the spot diameter of the laser beam. It is possible to reduce the width. For this reason, it becomes possible to form a pattern finer than the diffraction limit with respect to the wavelength of the laser beam.
Microelectornic Engineering 73-74 (2004) 69-73

  However, in the pattern forming method using the first reaction layer and the second reaction layer, there is a limit to the height of the pattern to be formed. For example, the limit of the height of a fine pattern formed by the above method is about 20 nm, and there is a problem that the pattern height preferable for manufacturing an optical disk is not satisfied.

  Accordingly, an object of the present invention is to provide a new and useful pattern forming material, a pattern forming method, and an optical disc that solve the above-described problems.

  A specific problem of the present invention is to provide a pattern forming material and a pattern forming method capable of forming a fine pattern by an inexpensive method, and to provide an optical disc that is inexpensive and has a large recording capacity. It is.

In the first aspect of the present invention, the above-described problem is a pattern forming material formed on a substrate, and when heated, the first reaction layer and the second are expanded in volume by reacting with each other. a reaction layer of, by being heated, possess a third reaction layer expands volume, a, the third reaction layer, platinum oxide, silver oxide, palladium oxide, and tungsten oxide Among these, the problem is solved by a pattern forming material characterized by containing any one metal oxide .

  According to the pattern forming material, in addition to the first reaction layer and the second reaction layer, by providing the third reaction layer whose volume expands when heated, the height of the pattern to be formed is increased. The height can be increased.

  In addition, when a thermal buffer layer is formed between the first reaction layer, the second reaction layer, the reaction layer portion including the third reaction layer, and the substrate, the substrate is heated. It is protected from damage caused by the above.

Further, the heat buffer layer is formed on the substrate, wherein the third reaction layer is formed on the skilled heat buffer layer, the to the third reaction layer on the second reaction layer is formed, the It is preferable that the first reaction layer is formed on the second reaction layer.

  Further, the first reaction layer is formed on the substrate, the second reaction layer is formed on the first reaction layer, and the third reaction layer is formed on the second reaction layer. It is preferable that

  In addition, it is preferable that a protective layer is formed on the third reaction layer because the loss of volume expansion of the third reaction layer is suppressed.

Further, the first reaction layer, to include sulfate zinc and silicon dioxide, the reaction volume expansion of the first reaction layer and second reaction layer is improved, which is preferable.

  Further, it is preferable that the second reaction layer contains at least two kinds of metals including a transition metal because the volume expansion reaction between the first reaction layer and the second reaction layer becomes good.

  In addition, it is preferable that the second reaction layer contains Tb, Fe, and Co because the volume expansion reaction between the first reaction layer and the second reaction layer is good.

  Further, it is preferable that the third reaction layer contains a metal oxide because the volume expansion reaction of the third reaction layer becomes good.

  In addition, when the metal oxide includes any one of platinum oxide, silver oxide, palladium oxide, and tungsten oxide, the volume expansion reaction of the third reaction layer becomes favorable, which is preferable. It is.

  In the second aspect of the present invention, the above problem is a pattern forming method using the pattern forming material, wherein the first reaction layer is irradiated with active light. And the second reaction layer are reacted to expand the volume and the volume of the third reaction layer is expanded to form a protruding pattern on the pattern forming material. ,Resolve.

  According to the pattern formation method, in addition to the first reaction layer and the second reaction layer, the third reaction layer whose volume is expanded by being heated is provided, thereby increasing the height of the pattern to be formed. The height can be increased.

  Further, when the active light is a laser beam in the visible range, a fine pattern can be formed at low cost.

  Further, if the width of the protruding pattern is equal to or less than the diffraction limit of the active light, a fine pattern can be formed at low cost.

  In addition, it is preferable that the height of the protruding pattern is 30 nm or more.

An optical disk formed by using the above pattern forming method is manufactured at a low cost and has a large recording capacity because of its fine pit shape.

  According to the present invention, a pattern forming material and a pattern forming method capable of forming a fine and high aspect ratio pattern by an inexpensive method are provided, and an inexpensive optical disk having a large recording capacity is provided. It becomes possible to do.

  Next, embodiments of the present invention will be described below with reference to the drawings.

  FIG. 2 is a cross-sectional view schematically showing a pattern forming material according to Example 1 of the present invention.

  Referring to FIG. 2, the pattern forming material shown in this drawing has a structure in which a reaction layer that causes a reaction by heating is laminated on a substrate 5. For example, the first reaction layer 4 and the second reaction layer 3 laminated so as to be in contact with the first reaction layer 4 are configured to react by heating and expand in volume.

  For example, when the active light such as laser is irradiated and heated, the first reaction layer 4 and the second reaction layer 3 made of the mixture each cause diffusion of the mixture, and further, the first reaction layer. It is considered that interdiffusion occurs between 4 and the second reaction layer 3, and the volume is considered to expand due to reactions including these diffusion reactions.

For example, the first reaction layer 4, when such a layer of vulcanized zinc (ZnS) and silicon dioxide mixture comprising _{(SiO 2) (ZnS-SiO} 2), the reaction is as good as is the reaction volume expansion Has been confirmed to be good.

  Further, when the second reaction layer 3 contains at least two kinds of metals including transition metals, the reaction is preferably good, and the second reaction layer includes Tb, Fe, and When Co (TbFeCo) is contained, the reaction is further improved and the reaction of the deposition expansion is improved, which is further preferable.

  By such volume expansion due to the mutual reaction between the first reaction layer 4 and the second reaction layer 3, a protruding fine pattern is formed which is convex upward when viewed from the first reaction layer 4 side. It is possible. However, conventionally, there is a problem that the height of the pattern that can be formed is not sufficient.

  Therefore, in the present embodiment, in addition to the first reaction layer and the second reaction layer that react with each other in this way, a third reaction layer 2 in which a reaction in which the volume expands due to heating is generated is provided. The first reaction layer and the second reaction layer react with each other by heating, whereas the third reaction layer 2 is heated substantially by the third reaction layer alone. It is formed so that a reaction occurs and the volume expands. For this reason, the height of the third reaction layer is increased by the volume expansion of the third reaction layer in addition to the interaction between the first reaction layer and the second reaction layer. It is possible. For this reason, it is possible to form a pattern having a fine pattern width and a high pattern height, that is, a so-called high aspect ratio.

  For example, the third reaction layer is formed so as to contain a compound, and is configured such that the volume expands when the compound is decomposed by heating. As an example of such a compound, for example, when the third reaction layer contains a metal oxide, a reaction in which oxygen is released from the metal occurs when heated, so that the volume expansion reaction is good. It is preferable. In addition, it is more preferable that such a metal oxide includes any one of platinum oxide, silver oxide, palladium oxide, and tungsten oxide because the reaction becomes further favorable.

  Further, in the patterning material according to the present embodiment, at least the first reaction layer and the second reaction layer configured to react with each other by heating and the third reaction layer that reacts substantially in a single layer are provided. Although it is configured to include other layers, it may be configured to include other layers, and the structure in which the above layers are stacked can be arbitrarily changed and used.

  For example, as shown in the figure, between the substrate 5 and a reaction layer portion including the first reaction layer 4, the second reaction layer 3, and the third reaction layer 2, which reacts by heating. Further, a heat buffer layer 1 for protecting the substrate from heat may be provided. Various materials can be used for such a thermal buffer layer, but in this embodiment, the thermal buffer layer is formed using the same material as the first reaction layer 4. For this reason, for example, equipment for forming the thermal buffer layer (a sputtering apparatus, a target of the sputtering apparatus, etc.) can be shared with that for forming the first reaction layer, so that the thermal buffer layer can be formed at low cost.

As an example in which a patterned material, in this figure, the substrate 5 said heat buffer layer 1 on it is formed, the third reaction layer 2 is formed on those thermal buffer layer 1, the first 3 shows an example in which the second reaction layer 3 is formed on the third reaction layer 2 and the first reaction layer 4 is formed on the second reaction layer 3. It is not limited. For example, as shown in FIG. 3, the configuration of FIG. 2 may be changed next.

  FIG. 3 shows a modification of the pattern forming material shown in FIG. However, in the figure, the same reference numerals are given to the parts described above, and the description thereof is omitted.

  In the pattern forming material shown in this figure, the third reaction layer 2 and the second reaction layer 3 in the pattern forming material shown in FIG. 2 are interchanged.

  Therefore, the heat buffer layer 1 functions as a first reaction layer in the case shown in the figure, and reacts with the second reaction layer 3 by heating. The first reaction layer 4 functions as a protective layer for the third reaction layer 2. For example, when the third reaction layer is expanded by heating, a large number of pores are formed in the layer due to decomposition of the compound, for example, desorption of oxygen. There is a problem that when such a hole is inserted into the atmosphere side, that is, when the hole bursts, volume expansion does not occur or the volume expansion rate decreases. Therefore, a protective layer is required on the third reaction layer 2 to protect the rupture of vacancies formed, and the first reaction layer 4 functions as a protective layer. Moreover, although the said protective layer can be formed with various materials, since equipment can be shared with the case where the 1st reaction layer is formed if it forms with the material similar to the 1st reaction layer, the cost which forms a protective layer It will be cheap.

  As described above, the pattern forming material according to the present invention has various configurations such as the first reaction layer, the second reaction layer, the third reaction layer, and the thermal buffer layer or the protective layer provided as necessary. However, the present invention is not limited to the above configuration example.

  In addition, the patterning material according to this example causes volume expansion and pattern formation when heated, but it is possible to form a fine pattern by controlling a region where reaction occurs due to heating. For example, when a laser beam is used, it is possible to form a fine pattern below the diffraction limit of the laser beam.

FIG. 4 shows the temperature distribution of the second reaction layer 3 when the pattern forming material shown in FIG. 2 is heated using a red laser in the visible region. In the case of red laser light, the beam spot diameter is approximately 1 μm, and it is difficult to make it smaller than this. In FIG. 4, the vertical axis represents temperature and the horizontal axis represents the position in the horizontal direction, but the temperature distribution is substantially Gaussian. Here, by controlling the intensity of the laser light applied to the pattern forming material, the temperature of a part of the region can be made higher than a predetermined threshold value T ₀ . At the portion where the temperature is higher than a predetermined threshold value T ₀ , the first reaction layer 4 and the second reaction layer 3 interact with each other, resulting in volume expansion. In this case, since the first reaction layer 4 has a relatively high transmittance of laser light, a temperature increase due to laser heating mainly occurs in the second reaction layer 3, and the second reaction layer 3 The first reaction layer 4 is indirectly heated by the heat conduction. In this case, since the width W of the region where the temperature is equal to or higher than the threshold is smaller than the beam spot diameter of the laser light, in this embodiment, it is possible to process a fine pattern having a width equal to or smaller than the diffraction limit. Further, the volume expansion due to the reaction between the first reaction layer 4 and the second reaction layer 3 is approximately when, for example, ZnS—SiO ₂ is used for the first reaction layer and TbFeCo is used for the second reaction layer. Although it occurs at 200 ° C. or higher, when it is 400 ° C. or higher, the reaction is favorable, and the volume expansion is further increased at 500 ° C. or higher, which is more preferable.

  Similarly, the volume expansion generated in the third reaction layer 2 is controlled so that a region smaller than the spot diameter of the laser beam becomes the threshold value of the reaction temperature as in the above reaction. Can be formed. For example, when platinum oxide (PtOx) is used for the third reaction layer, the volume expansion increases at 500 ° C. or higher.

  For this reason, it is preferable to irradiate a laser beam so that the area | region which pattern-forms in the said 2nd reaction layer 3 and the 3rd reaction layer 2 may be 500 degreeC or more. Further, the width of the pattern can be controlled by adjusting the intensity of the laser beam.

  Next, a method for performing pattern formation by irradiating the pattern forming material with active light, for example, laser, will be specifically described. FIG. 5 schematically shows a method for forming a fine pattern by irradiating the pattern forming material shown in FIG. 2 with laser light. However, in the figure, the same reference numerals are given to the parts described above, and the description thereof is omitted.

  The patterning material is irradiated with laser light L collected by the lens F from the substrate 5 side. Here, the second reaction layer 3 is heated, the second reaction layer 3 and the first reaction layer 4 react to expand the volume, and the expansion portion 34a is formed. Further, the third reaction layer 2 is heated, the volume expands, and the expanded portion 2a is formed. Thus, since the expansion part 34a and the expansion part 2a are formed, a protruding pattern is formed on the surface of the patterning material opposite to the substrate. In addition, since the pattern height H1 receives the effect of volume expansion of the expanded portion 34a and the expanded portion 2a, it can be made higher than before, can be set to 30 nm or more, and can be formed to approximately 40 nm. ing. In this case, the pattern width W1 can be set to 150 nm or less, and it is confirmed that the pattern width W1 can be formed up to about 100 nm.

  That is, according to the present embodiment, it is possible to form a fine pattern by using an inexpensive laser beam in the visible range, and it is possible to further increase the pattern height compared to the conventional case. It is possible to form a fine pattern with a high so-called aspect ratio.

  Further, the active light used in this embodiment is not limited to the red laser, and it is obvious that various other active lights can be used.

  Moreover, in the structure shown in this figure, the preferable thickness of each layer is such that the thermal buffer layer 1 is 10 to 500 nm, the third reaction layer 2 is 2 to 50 nm, and the second reaction layer 3 is 10-100 nm, the said 1st reaction layer 4 is 10-500 nm.

  Next, the result of processing a fine pattern using the method shown in FIG. 5 is shown. FIG. 6 (A) shows the surface of the pattern material after pattern processing is measured by an atomic force microscope (AFM) and the result is displayed on a computer screen. 6B shows the cross-sectional shape of FIG.

  The conditions for forming the pattern are as follows.

The pattern forming material was rotated so that the linear velocity was 3 m / s, and irradiated with a pulse laser having a frequency of 15 MHz, an output of 9 mW, and a duty ratio of 30%. A material made of ZnS—SiO ₂ is used for the first reaction layer 4 and the thermal buffer layer 1, a material made of TbFeCo is used for the second reaction layer 3, and the third reaction layer is also made. For this, a material made of PtOx was used, and a substrate made of SiO ₂ was used.

  6A and 6B, it is confirmed that a dot having a diameter of approximately 110 nm is formed on the pattern forming material, and that the height of the dot is approximately 40 nm. It has been confirmed that a pattern height of about 20 nm in the past can be formed at a height approximately twice as high.

  Next, an example of a method for forming an optical disc using the pattern forming method shown in FIG. 5 will be described.

  FIG. 7 is a flowchart showing a so-called mastering process when the pattern forming method shown in FIG. 5 is applied to the production of an optical disc master.

  In the mastering process, the master uses a glass disk or the like as a substrate (step S1). After polishing the glass disk (step S2), inspecting (step S3), and cleaning (step S4), the pattern forming material that is the multilayer structure shown in FIG. 2 is formed by a film forming method such as sputtering. (Step S5) and inspection (Step S6).

  On the other hand, the information to be recorded on the master is edited in advance as information to be written on the optical disc by the editing device (step S7). The edited information is sent out by the signal sending device (step S8) and recorded as pits which are fine patterns on the pattern forming material formed in a glass disk shape (step S9). The signal sending device converts information sent from the editing device into an intensity signal of the laser beam, and irradiates the pattern forming material with the laser beam. Pits are formed in the pattern forming material by irradiation with laser light. By applying the pattern forming method shown in FIG. 5 in step S9, it is possible to form pits that are smaller than the diffraction limit of the signal sending device.

  After forming pits in the pattern forming material with laser light, a step of etching the patterning material may be provided (step S10). By selectively etching a region where no pit is formed, the aspect ratio of the master can be improved. Next, the electrode for a plating process is apply | coated to a glass disk (step S11), and it test | inspects (step S12). A stamper is formed on the master by plating or the like (step S13), and the stamper is separated from the master (step S14). The above is the so-called mastering process of the optical disc.

  FIG. 8 is a diagram showing a so-called replication process for producing an optical disk using a stamper created by the mastering method.

  Using the stamper created in the mastering process (step S20), polycarbonate or the like is injection molded by an injection molding machine (step S21). A reflective film is applied to the injection molded product (step S22), and a protective film is further applied (step S23). As described above, a large-capacity optical disk having a fine pattern can be produced at low cost.

  Further, it is apparent that the pattern forming material and the pattern forming method according to the present invention are not limited to the production of optical discs and can be applied to recording media and devices having various fine patterns.

  Although the present invention has been described with reference to the preferred embodiments, the present invention is not limited to the specific embodiments described above, and various modifications and changes can be made within the scope described in the claims.

  According to the present invention, a pattern forming material and a pattern forming method capable of forming a fine and high aspect ratio pattern by an inexpensive method are provided, and an inexpensive optical disk having a large recording capacity is provided. It becomes possible to do.

It is sectional drawing which showed the conventional pattern formation material typically. 2 is a cross-sectional view schematically showing a pattern forming material according to Example 1. FIG. It is a figure which shows the modification of the pattern formation material of FIG. It is the figure which showed typically the temperature distribution of the pattern formation material at the time of irradiating a laser. It is the figure which showed typically the pattern formation method by Example 1. FIG. (A) is the image which measured the pattern formed by the pattern formation method of FIG. 5 with AFM, (B) is a figure which shows the profile of the cross-sectional structure. FIG. 6 is a flowchart (part 1) in which the pattern forming method of FIG. 5 is applied to an optical disc production method. FIG. 6 is a flowchart (part 2) in which the pattern forming method of FIG. 5 is applied to an optical disc production method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thermal buffer layer 2 3rd reaction layer 3,200 2nd reaction layer 4,100,300 1st reaction layer 5,400 Substrate L Laser beam F Lens W1 Pattern width H1 Pattern height

Claims (13)

A pattern forming material formed on a substrate,
A first reaction layer and a second reaction layer whose volumes expand by reacting with each other;
A third reaction layer whose volume expands when heated,
The pattern forming material, wherein the third reaction layer includes any one metal oxide of platinum oxide, silver oxide, palladium oxide, and tungsten oxide.   The thermal buffer layer is formed between the reaction layer part including the first reaction layer, the second reaction layer, and the third reaction layer, and the substrate. 1. The pattern forming material according to 1.   The thermal buffer layer is formed on the substrate, the third reaction layer is formed on the thermal buffer layer, the second reaction layer is formed on the third reaction layer, and the second reaction layer is formed. The pattern forming material according to claim 2, wherein the first reaction layer is formed on the reaction layer.   The first reaction layer is formed on the substrate, the second reaction layer is formed on the first reaction layer, and the third reaction layer is formed on the second reaction layer. The pattern forming material according to claim 1, wherein:   The pattern forming material according to claim 4, wherein a protective layer is formed on the third reaction layer.   The pattern forming material according to claim 1, wherein the first reaction layer contains zinc sulfide and silicon dioxide.   The pattern forming material according to claim 1, wherein the second reaction layer includes at least two kinds of metals including a transition metal.   The pattern forming material according to claim 1, wherein the second reaction layer contains Tb, Fe, and Co. A pattern forming method using the pattern forming material according to any one of claims 1 to 8,
By irradiating the pattern forming material with active light, the first reaction layer and the second reaction layer are reacted to expand the volume, and the volume of the third reaction layer is expanded to form the pattern. A pattern forming method comprising forming a projection-like pattern on a material.   The pattern forming method according to claim 9, wherein the active light is a visible laser beam.   The pattern forming method according to claim 9, wherein a width of the protruding pattern is equal to or less than a diffraction limit of the active light.   The pattern forming method according to claim 9, wherein a height of the protruding pattern is 30 nm or more.   An original disc of an optical disk formed by using the method according to any one of claims 9 to 12.

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