Laminates, imprint molds, optical elements, and electronic devices

Abstract

The present invention provides a laminate that can suppress damage to the glass surface when etching a thin film formed on a glass substrate. [Solution] The laminate comprises a substrate and a protective film formed on the substrate. The total content of lanthanum oxide, barium oxide, strontium oxide, calcium oxide, and magnesium oxide in the substrate is 0% by mass or more and 20.0% by mass or less. The silicon dioxide content of the substrate is 0% by mass or more and 50% by mass or less. The protective film contains at least one selected from the group of metals consisting of scandium, manganese, yttrium, zirconium, nickel, lanthanum, cerium, neodymium, vanadium, chromium, iron, gallium, silver, indium, tin, tantalum, hafnium, lead, ruthenium, palladium, iridium, platinum, and thallium.

Description

[Technical Field]

[0001] The present invention relates to a laminate, an imprint mold, an optical element, and an electronic device including an optical element, which are particularly suitable for use as a substrate for imprint molds or as a substrate for optical elements such as diffraction gratings. [Background technology]

[0002] With the advancement of AR (Augmented Reality) technology, goggle-type or glasses-type display devices have been developed as AR devices (Patent Documents 1, 2, etc.). For example, goggle-type or glasses-type display devices preferably use lenses with a high refractive index and low specific gravity, and there is a growing demand for glass that can be used for such lenses. Conventionally, the following method is used to manufacture the above-mentioned lenses using such glass.

[0003] For example, cut pieces are prepared by cutting, grinding, and polishing a desired plate-shaped glass material as appropriate. These cut pieces are heated and softened, then press-formed. After press-forming, the cut pieces are annealed, and further ground and polished. This allows for the production of the lens described above. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2010-243787 [Patent Document 2] International Publication No. 2017 / 018375 [Overview of the project] [Problems that the invention aims to solve]

[0005] Furthermore, diffraction gratings are used as part of the lenses in the goggle-type or glasses-type display devices described above. These diffraction gratings are obtained, for example, by forming an uneven pattern on a thin film with a high refractive index formed on the surface of glass. This uneven pattern is obtained by partially removing the thin film using a predetermined etching material.

[0006] The inventors considered using glass with a high refractive index and low specific gravity as described above for use in diffraction gratings. As a result, the inventors discovered a new problem: when etching a thin film formed on the surface of such glass, the exposed glass surface can be damaged. This damage to the exposed glass surface significantly degrades the optical performance of the fabricated diffraction grating. Conventionally, glass with a high refractive index and low specific gravity as described above was manufactured with the intention of being used as a lens obtained by annealing, grinding, and polishing cut pieces after press molding. Therefore, the problem of the glass surface being exposed to the etching material when forming an uneven pattern on a thin film formed on the glass surface was not considered conventionally.

[0007] The inventors of this invention have newly discovered a problem in that when etching a thin film formed on the surface of such high refractive index and low specific gravity glass, the exposed glass surface may be damaged by exposure to the etching material for the thin film. The present invention aims to solve this problem.

[0008] In other words, the object of the present invention is to provide a laminate that can suppress damage to the glass surface when etching a thin film formed on a glass substrate. Another object is to provide an imprint mold, optical element, and electronic device using this laminate as a substrate. [Means for solving the problem]

[0009] As a result of diligent research to solve the above problems, the inventors have completed an invention having the following configuration.

[0010] (Composition 1) A laminate comprising a substrate and a protective film formed on a first main surface of the substrate, wherein the total content of lanthanum oxide, barium oxide, strontium oxide, calcium oxide, and magnesium oxide in the substrate is 0% by mass or more and 20.0% by mass or less, the silicon dioxide content in the substrate is 0% by mass or more and 50% by mass or less, and the protective film is made of a material containing at least one selected from the group of metals consisting of scandium, manganese, yttrium, zirconium, nickel, lanthanum, cerium, neodymium, vanadium, chromium, iron, gallium, silver, indium, tin, tantalum, hafnium, lead, ruthenium, palladium, iridium, platinum, and thallium.

[0011] (Configuration 2) The laminate according to configuration 1, characterized in that the protective film contains oxygen or nitrogen. (Composition 3) The laminate according to configuration 1 or 2, characterized in that the protective film is formed in contact with the first main surface.

[0012] (Composition 4) A laminate according to any one of configurations 1 to 3, characterized in that it has a first film on the protective film. (Composition 5) The laminate according to any one of configurations 1 to 4, characterized in that the silicon dioxide content of the substrate is 10% by mass or less.

[0013] (Composition 6) The laminate according to any one of configurations 1 to 5, characterized in that the protective film is formed to cover 80% or more of the first main surface of the substrate. (Composition 7) The laminate according to any one of configurations 1 to 6, characterized in that the region on the substrate on which the protective film is laminated has a transmittance of 50% or more for light in the wavelength range of 400 nm to 700 nm.

[0014] (Configuration 8) An imprint mold, wherein a pattern including a concave portion is formed on the first film described in Configuration 4.

[0015] (Configuration 9) An optical element comprising a substrate, a protective film formed on a first main surface of the substrate, a first film provided with a pattern including a concave portion and formed on the protective film, wherein in the substrate, the total content of lanthanum oxide, barium oxide, strontium oxide, calcium oxide and magnesium oxide is 0 mass% or more and 20.0 mass% or less, the content of silicon dioxide in the substrate is 0 mass% or more and 50 mass% or less, and the protective film is made of a material containing at least one selected from the group of metals consisting of scandium, manganese, yttrium, zirconium, nickel, lanthanum, cerium, neodymium, vanadium, chromium, iron, gallium, silver, indium, tin, tantalum, hafnium, lead, ruthenium, palladium, iridium, platinum and thallium.

[0016] (Configuration 10) The optical element according to Configuration 9, wherein the protective film contains oxygen or nitrogen. (Configuration 11) The optical element according to Configuration 9 or 10, wherein the protective film is formed in contact with the first main surface.

[0017] (Configuration 12) The optical element according to any one of Configurations 9 to 11, wherein the content of silicon dioxide in the substrate is 10 mass% or less. (Configuration 13) The optical element according to any one of Configurations 9 to 12, wherein the protective film is formed so as to cover 80% or more of the first main surface of the substrate.

[0018] (Configuration 14) The optical element according to any one of configurations 9 to 13, characterized in that the region on the substrate in which the protective film and the first film are laminated has a transmittance of 50% or more for light in the wavelength range of 400 to 700 nm.

[0019] (Composition 15) An electronic device characterized by including an optical element as described in any of configurations 9 to 14. [Effects of the Invention]

[0020] According to the present invention, when etching a thin film formed on a glass substrate, it is possible to provide a laminate that can suppress damage to the glass surface from the etching material. Furthermore, by using this laminate as a substrate, the present invention can provide high-precision and high-performance imprint molds, optical elements, and electronic devices. [Brief explanation of the drawing]

[0021] [Figure 1] This is a cross-sectional view showing the layer structure of one embodiment of the laminate according to the present invention. [Figure 2] This is a cross-sectional view showing the layer configuration of another embodiment of the laminate according to the present invention. [Figure 3] This is a cross-sectional view showing one embodiment of the optical element according to the present invention. [Figure 4] (a) to (c) are cross-sectional views illustrating the manufacturing process of an optical element according to one embodiment of the present invention. [Figure 5] This is a cross-sectional view showing the layer structure of a laminate used in the fabrication of optical elements of other embodiments. [Figure 6] This is a cross-sectional view showing an optical element of another embodiment. [Modes for carrying out the invention]

[0022] The embodiments for carrying out the present invention will be described in detail below with reference to the drawings.

[0023] [Laminated structure] The laminate of the present invention will now be described. The laminate of the present invention is suitably used, for example, as a substrate for optical elements such as diffraction gratings, or as a substrate for imprint molding.

[0024] Figure 1 is a cross-sectional view showing the layer structure of one embodiment of the laminate according to the present invention. As shown in Figure 1, the laminate 10 of one embodiment of the present invention comprises a substrate 1 and a protective film 2 formed on the first main surface of the substrate 1.

[0025] In the present invention, the substrate 1 has two opposing main surfaces (a first main surface and a second main surface) and an end surface located between the two main surfaces. The substrate 1 can be a glass substrate containing at least one of lanthanum oxide (La2O3), barium oxide (BaO), strontium oxide (SrO), calcium oxide (CaO), magnesium oxide (MgO), and silicon dioxide (SiO2). Preferably, the total content of lanthanum oxide (La2O3), barium oxide (BaO), strontium oxide (SrO), calcium oxide (CaO), and magnesium oxide (MgO) in the substrate 1 is 0% by mass or more and 20.0% by mass or less. Preferably, the content of silicon dioxide (SiO2) in the substrate 1 is 0% by mass or more and 50% by mass or less. The substrate 1 described above does not necessarily have to contain any of lanthanum oxide (La2O3), barium oxide (BaO), strontium oxide (SrO), calcium oxide (CaO), magnesium oxide (MgO), or silicon dioxide (SiO2). Furthermore, in order to better achieve the effects of the present invention, the substrate 1 is preferably a glass substrate with a high refractive index and low specific gravity. The following describes one embodiment of the substrate 1 described above, specifically the case where it is a glass substrate.

[0026] <Glass substrate (substrate 1)> In this specification, glass composition is expressed on an oxide basis unless otherwise specified. Here, "glass composition on an oxide basis" refers to the glass composition obtained by calculating it as if all glass raw materials were decomposed during melting and existed as oxides in the glass. The total content of all glass components expressed on an oxide basis (excluding Sb (Sb2O3), Ce (CeO2), and Sn (SnO2) added as clarifying agents) shall be 100% by mass. Each glass component shall be written as SiO2, TiO2, etc., following convention.

[0027] The content of glass components can be quantified by known methods, such as inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS). In this specification, a content of 0% by mass of a component means that the component is substantially absent, and it is permissible for the component to be present at an unavoidable impurity level.

[0028] The following describes the glass components contained in the substrate 1 mentioned above. As described above, in the present invention, the total content of La2O3, BaO, SrO, CaO, and MgO in the substrate 1 is preferably 0% by mass or more and 20.0% by mass or less. These components have the function of lowering the melting temperature of the glass and improving the thermal stability of the glass. By setting the total content of La2O3, BaO, SrO, CaO, and MgO in the range of 0% by mass or more and 20.0% by mass or less, a glass substrate with a high refractive index, high stability, and low specific gravity can be obtained. In the present invention, the total content of La2O3, BaO, SrO, CaO, and MgO is more preferably 15% by mass or less, and even more preferably 10% by mass or less.

[0029] The following are non-limiting examples of the content, ratio, and properties of glass components other than those mentioned above in the optical glass according to this embodiment.

[0030] The optical glass according to this embodiment is substantially free of F (fluorine). That is, in the optical glass according to this embodiment, the anionic component is mainly O (oxygen). When expressed as a mass % relative to the total amount of glass based on oxides, the F content is preferably less than 1.0% on an external basis, and more preferably 0.5% or less, 0.2% or less, and 0.1% or less, in that order.

[0031] Here, "external division" refers to the amount of F component expressed in mass percentage, assuming that all the cationic components constituting the glass are oxides bonded with oxygen in sufficient quantities to balance the charge, and that the total amount of material in the glass made of these oxides is 100%.

[0032] Furthermore, in this embodiment, the SiO2 content of the substrate 1 is preferably 0% by mass or more and 50% by mass or less. By setting the SiO2 content within this range, a glass substrate with a high refractive index, high stability, and low specific gravity can be obtained. SiO2 is a network-forming component of glass and improves the thermal stability, chemical durability, and weather resistance of the glass, increases the viscosity of the molten glass, and makes the molten glass easier to mold. By having the SiO2 content within the above range, a desired refractive index can be obtained. In the present invention, the SiO2 content is preferably 30% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less, and particularly preferably 3% by mass or less. The substrate 1 does not have to contain SiO2. In this embodiment, the substrate 1 is a glass substrate with a high refractive index and low specific gravity.

[0033] In this embodiment, the La2O3 content of the substrate 1 is preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less, and particularly preferably 3% by mass or less. La2O3 can increase the refractive index of the glass. By having the La2O3 content within the above range, it is possible to suppress an increase in the specific gravity of the glass, a decrease in the thermal stability of the glass, and an increase in the melting temperature of the glass. Note that the substrate 1 does not have to contain La2O3.

[0034] In this embodiment, the BaO content of the substrate 1 is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 8% by mass or less. Furthermore, the BaO content of the substrate 1 is preferably 3% by mass or more. BaO can lower the melting temperature of the glass and improve its thermal stability and devitrification resistance. By keeping the BaO content within the above range, an increase in specific gravity can be suppressed, and a desired refractive index can be obtained. Furthermore, a decrease in the thermal stability and devitrification resistance of the glass can be suppressed. Note that the substrate 1 does not necessarily have to contain BaO.

[0035] In this embodiment, the SrO content of the substrate 1 is preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less, and particularly preferably 3% by mass or less. SrO can lower the melting temperature of the glass and improve its thermal stability and devitrification resistance. By keeping the SrO content within the above range, an increase in specific gravity can be suppressed and a desired refractive index can be obtained. Furthermore, a decrease in the thermal stability and devitrification resistance of the glass can be suppressed. Note that the substrate 1 does not necessarily have to contain SrO.

[0036] In this embodiment, the CaO content of the substrate 1 is preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less, and particularly preferably 3% by mass or less. Furthermore, the substrate 1 does not need to contain CaO. CaO can lower the melting temperature of the glass and improve its thermal stability and devitrification resistance. By having a CaO content within the above range, a desired refractive index can be obtained, and a decrease in the thermal stability and devitrification resistance of the glass can be suppressed.

[0037] In this embodiment, the MgO content of the substrate 1 is preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less, and particularly preferably 3% by mass or less. Note that the substrate 1 does not have to contain MgO. MgO can lower the melting temperature of the glass and improve its thermal stability and devitrification resistance. By having an MgO content within the above range, a desired refractive index can be obtained, and a decrease in the thermal stability and devitrification resistance of the glass can be suppressed.

[0038] In this embodiment, the P2O5 content of the substrate 1 is preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 40% by mass or less. Furthermore, the P2O5 content of the substrate 1 is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more. P2O5 is a network-forming component of glass and is effective in containing a large amount of highly dispersed components in the glass. By setting the P2O5 content within the above range, it becomes easier to obtain the desired refractive index and to control the melting temperature within an appropriate range.

[0039] In this embodiment, the Li2O content of the substrate 1 is preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less, and particularly preferably 3% by mass or less. Note that the substrate 1 does not have to contain Li2O. By setting the Li2O content within the above range, the melting temperature can be reduced, the specific gravity can be lowered, and the thermal stability of the glass can be improved. In addition, Li2O contributes to a higher refractive index among alkaline components. By keeping the Li2O content within the above range, a desired refractive index can be obtained, and a decrease in thermal stability, chemical durability, and weather resistance can be suppressed.

[0040] In this embodiment, the Na2O content of the substrate 1 is preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less, and particularly preferably 3% by mass or less. Note that the substrate 1 does not necessarily have to contain Na2O. Na2O can lower the melting temperature, improve the thermal stability of the glass, and contribute to lowering the specific gravity. By having a Na2O content within the above range, a desired refractive index can be obtained.

[0041] In this embodiment, the K2O content of the substrate 1 is preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less, and particularly preferably 3% by mass or less. Note that the substrate 1 does not necessarily have to contain K2O. K2O can lower the melting temperature, improve the thermal stability of the glass, and contribute to lowering the specific gravity. By having a K2O content within the above range, a desired refractive index can be obtained.

[0042] In this embodiment, the TiO2 content of the substrate 1 is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. Furthermore, the TiO2 content of the substrate 1 is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more. TiO2 greatly contributes to high refractive index and high dispersion. In addition, TiO2 contributes to low specific gravity among the high refractive index components. By setting the TiO2 content within the above range, both high refractive index and low specific gravity can be achieved, and chemical durability can also be improved. Furthermore, by setting the TiO2 content within the above range, the decrease in transparency of the glass due to crystal formation within the glass during the process of obtaining the glass substrate (clouding) can be suppressed. It can also suppress discoloration of the glass.

[0043] In this embodiment, the Nb2O5 content of the substrate 1 is preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less. Furthermore, the Nb2O5 content of the substrate 1 is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more. Nb2O5 contributes to high refractive index and high dispersion. By setting the Nb2O5 content within the above range, the thermal stability and chemical durability of the glass can be improved. By keeping the Nb2O5 content within the above range, it is possible to suppress an increase in melting temperature, a decrease in the thermal stability of the glass, and discoloration of the glass. It is also possible to suppress an increase in the specific gravity of the glass.

[0044] In this embodiment, the WO3 content of the substrate 1 is preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 3% by mass or less, and particularly preferably 1% by mass or less. Note that the substrate 1 does not have to contain WO3. WO3 can increase the refractive index of the glass. By keeping the WO3 content within the above range, an increase in specific gravity and a decrease in thermal stability can be suppressed.

[0045] In this embodiment, the B2O3 content of the substrate 1 is preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less. Note that the substrate 1 does not necessarily have to contain B2O3. B2O3 can increase the refractive index of the glass. By keeping the B2O3 content within the above range, discoloration and an increase in specific gravity of the glass can be suppressed.

[0046] In this embodiment, the ZnO content of the substrate 1 is preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 3% by mass or less, and particularly preferably 1% by mass or less. Note that the substrate 1 does not necessarily have to contain ZnO. ZnO can lower the melting temperature of the glass and improve its thermal stability and devitrification resistance. By keeping the ZnO content within the above range, an increase in specific gravity can be suppressed, and a desired refractive index can be obtained. Furthermore, a decrease in the thermal stability and devitrification resistance of the glass can be suppressed.

[0047] In this embodiment, the Bi2O3 content of the substrate 1 is preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 3% by mass or less, and particularly preferably 1% by mass or less. Note that the substrate 1 does not have to contain Bi2O3. Bi2O3 can increase the refractive index of the glass. By keeping the Bi2O3 content within the above range, discoloration and an increase in specific gravity of the glass can be suppressed.

[0048] In this embodiment, the Al2O3 content of the substrate 1 is preferably 2.0% by mass or less, more preferably 1.5% by mass or less, even more preferably 1.0% by mass or less, and particularly preferably 0.5% by mass or less. Note that the substrate 1 does not have to contain Al2O3. Al2O3 is a network-forming component of glass and can improve the thermal stability, chemical durability, and weather resistance of the glass. By having the Al2O3 content within the above range, a desired refractive index can be obtained. Furthermore, it is possible to suppress the decrease in devitrification resistance of the glass due to an increase in the melting temperature and the decrease in thermal stability due to an increase in the glass transition temperature Tg.

[0049] In this embodiment, the ZrO2 content of the substrate 1 is preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 3% by mass or less, and particularly preferably 1% by mass or less. Note that the substrate 1 does not have to contain ZrO2. ZrO2 can increase the refractive index of the glass and improve its thermal stability and devitrification resistance. By keeping the ZrO2 content within the above range, it is possible to suppress an increase in specific gravity, an increase in melting temperature, and a decrease in the thermal stability of the glass.

[0050] In this embodiment, the Y2O3 content of the substrate 1 is preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 3% by mass or less, and particularly preferably 1% by mass or less. Note that the substrate 1 does not have to contain Y2O3. Y2O3 can increase the refractive index of the glass. By having the Y2O3 content within the above range, it is possible to suppress an increase in the specific gravity of the glass, a decrease in the thermal stability of the glass, and an increase in the melting temperature of the glass.

[0051] In addition, Sb(Sb2O3), Ce(CeO2), and Sn(SnO2) are substances that can be optionally added as fining agents. When the total content of all glass components other than Sb2O3, CeO2, and SnO2 is 100% by mass, the content of Sb2O3, CeO2, and SnO2 is preferably 2% by mass or less, respectively, but may be 0%.

[0052] Note that the refractive index n of the substrate 1 with respect to the d-line (wavelength 587.56 nm) d is preferably 1.5 or more, more preferably 1.7 or more, and even more preferably 1.95 or more. Also, the refractive index n of the substrate 1 with respect to the d-line d is preferably 2.5 or less, more preferably 2.3 or less, and even more preferably 2.2 or less. Also, the Abbe number ν of the substrate 1 d is preferably 20.0 or less, more preferably 19.0 or less, and even more preferably 18.0 or less. Also, the Abbe number ν of the substrate 1 d is preferably 15.0 or more, more preferably 16.0 or more. The Abbe number ν d is ν d =(n d -1) / (n F -n C ) and can be obtained. Here, n F is the refractive index of the substrate 1 with respect to the F-line (wavelength 486.13 nm), and n C is the refractive index of the substrate 1 with respect to the C-line (wavelength 656.27 nm).

[0053] The substrate 1 according to the present embodiment is a high refractive index glass but does not have a large specific gravity. If the specific gravity of the glass can be reduced, the weight of the lens can be decreased. On the other hand, if the specific gravity is too small, it may cause a decrease in thermal stability.

[0054] Therefore, in the substrate 1 according to the present embodiment, the upper limit of the specific gravity is preferably 4.20, and may further be 4.15, 4.10, 4.05, 4.00, 3.95, 3.90, 3.85, or 3.80.

[0055] In the substrate 1 according to this embodiment, the lower limit of the ratio of refractive index nd to specific gravity d (nd / d) is preferably 0.48, and may further be 0.49, 0.50, 0.51, or 0.52. The upper limit of the ratio (nd / d) is preferably 0.60, and may further be 0.59, 0.58, or 0.57. By satisfying the above ranges for refractive index nd and specific gravity d, a glass with a high refractive index and relatively reduced specific gravity can be obtained.

[0056] In the substrate 1 according to this embodiment, the upper limit of the glass transition temperature Tg is preferably 800°C, and may further be 780°C, 750°C, 730°C, or 700°C, from the viewpoint of lowering the temperature at which the glass is slowly cooled, the temperature at which it is heated and softened, or the press temperature. The lower limit of the glass transition temperature Tg is not particularly limited, but may be 380°C. Furthermore, from the viewpoint of making the network structure of the glass stronger and suppressing glass cracking, or from the viewpoint of reducing the thermal expansion of the glass and improving the heat resistance of the glass, the lower limit of the glass transition temperature Tg is preferably 390°C, and may further be 400°C, 410°C, 420°C, 430°C, or 440°C. In particular, for glass with a high refractive index, in order to improve heat resistance, the lower limit of the glass transition temperature Tg can be preferably 460°C, and may further be 480°C, 500°C, 510°C, 520°C, 530°C, or 535°C. The glass transition temperature (Tg) can be controlled primarily by adjusting the content of Li, Na, and K, their total content, the Zn content, the molar ratio [P / Al], and the molar ratio [Ba / P].

[0057] The light transmittance of the substrate 1 according to this embodiment can be evaluated by the degree of coloration λ70 and λ5. For a glass sample with a thickness of 10.0 mm ± 0.1 mm, the spectral transmittance is measured in the wavelength range of 200 to 700 nm, and the wavelength at which the external transmittance is 70% is defined as λ70, and the wavelength at which the external transmittance is 5% is defined as λ5.

[0058] The upper limit of λ70 of the substrate 1 according to this embodiment is preferably 650 nm, and may further be 640 nm, 630 nm, 620 nm, 610 nm, or 600 nm. The upper limit of λ5 of the substrate 1 is preferably 450 nm, and may further be 440 nm, 430 nm, 420 nm, 410 nm, or 400 nm.

[0059] <Manufacturing of glass substrates> The glass substrate constituting the above substrate 1 can be manufactured by blending glass raw materials to achieve a predetermined refractive index and composition, and then using the blended glass raw materials according to a known glass manufacturing method. For example, several types of compounds can be blended and thoroughly mixed to form a batch raw material, which can then be roughly melted in a quartz or platinum crucible. The molten material obtained from the rough melting is rapidly cooled and pulverized to produce cullet. The cullet is then heated in a platinum crucible and remelted to produce molten glass, which is then clarified and homogenized before being molded and slowly cooled to obtain a glass substrate. Known methods can be applied to the molding and slow cooling of the molten glass.

[0060] Furthermore, the compounds used when preparing the batch raw materials are not particularly limited, as long as the desired glass components can be introduced into the glass in the desired amounts. Examples of such compounds include oxides, carbonates, nitrates, hydroxides, and fluorides.

[0061] <Protective film> Next, I will explain the protective film. As shown in Figure 1, in the laminate 10 of one embodiment of the present invention, a protective film 2 is formed on the first main surface of the substrate 1. Preferably, the protective film 2 is formed in contact with the substrate 1 on the first main surface (one of the main surfaces) of the substrate 1. In other words, it is preferable that no other layers or films are interposed between the protective film 2 and the substrate 1. This makes it possible to protect the substrate 1 while maintaining a high light transmittance of the imprint mold, optical element, etc. obtained from the substrate 1.

[0062] In this embodiment, the protective film 2 is preferably made of a material containing at least one selected from the group of metals consisting of scandium (Sc), manganese (Mn), yttrium (Y), zirconium (Zr), nickel (Ni), lanthanum (La), cerium (Ce), neodymium (Nd), vanadium (V), chromium (Cr), iron (Fe), gallium (Ga), silver (Ag), indium (In), tin (Sn), tantalum (Ta), hafnium (Hf), lead (Pb), ruthenium (Ru), palladium (Pd), iridium (Ir), platinum (Pt), and thallium (Tl).

[0063] The protective film 2 preferably contains 20 atomic percent or more of a metal selected from the above group of metals, and more preferably contains 25 atomic percent or more. This allows the substrate 1 to be well protected from the etching material of the thin film when the thin film formed on the laminate 10 is etched.

[0064] Furthermore, in order to increase the transmittance of the protective film 2 to visible light (wavelength 400 nm to 700 nm), the protective film 2 preferably contains 80 atomic percent or less of a metal selected from the above group of metals, more preferably 75 atomic percent or less, and even more preferably 50 atomic percent or less.

[0065] On the other hand, as will be described in more detail later, when a substrate etched type optical element is manufactured by using a protective film 2 with a pattern formed on it as a mask to etch into the substrate 1, the protective film 2 preferably contains 98 atomic percent or less of a metal selected from the above group of metals, more preferably 95 atomic percent or less, and even more preferably 80 atomic percent or less.

[0066] Furthermore, the protective film 2 may include one or more elements selected from oxygen, nitrogen, carbon, and boron, in addition to the metal selected from the metal group. If it is preferable that the protective film 2 be transparent to visible light (wavelength 400 nm to 700 nm), the protective film 2 is preferably made of an oxide of the metal selected from the metal group, but it may also be a nitride of a metal that is transparent to visible light.

[0067] The protective film 2 preferably contains 30 atomic percent or more of oxygen. This ensures sufficient transparency to visible light. In particular, if the protective film 2 is made of an oxide of a metal selected from the above group of metals other than silver, it is preferable that it contains 40 atomic percent or more of oxygen. Furthermore, it is preferable that the protective film 2 contains 80 atomic percent or less of oxygen. This allows the protective film 2 to effectively protect the substrate 1.

[0068] When the protective film 2 is made of a metal nitride (e.g., GaN), it is preferable that the protective film 2 contains 30 atomic percent or more of nitrogen, more preferably 40 atomic percent or more, and even more preferably 45 atomic percent or more. In this case, it is preferable that the protective film 2 contains 60 atomic percent or less of nitrogen. This ensures sufficient transparency to visible light and allows the protective film 2 to effectively protect the substrate 1. When the protective film 2 is made of a material other than a metal nitride, it does not need to contain nitrogen, but if it does contain nitrogen, it is preferable that it contains 3 atomic percent or more of nitrogen, and more preferably 50 atomic percent or less. This ensures that the protective film 2 effectively protects the substrate 1.

[0069] When increasing the transmittance of the protective film 2 to visible light, the total content of nitrogen, carbon, and boron in the protective film 2 is preferably 70 atomic% or less, more preferably 60 atomic% or less, and even more preferably 55 atomic% or less. The protective film 2 does not need to contain nitrogen, carbon, and boron.

[0070] In this embodiment, the region on the substrate 1 on which the protective film 2 is laminated can have a transmittance of 50% or more for visible light (wavelength range of 400 nm to 700 nm).

[0071] Furthermore, the protective film 2 can be formed using a noble gas. Therefore, the protective film 2 may contain a noble gas. In this case, the noble gas content of the protective film 2 is preferably 5 atomic percent or less, and more preferably 3 atomic percent or less.

[0072] In this embodiment, the material for the protective film 2 is preferably, for example, Sc2O3, MnO, Mn2O4, Mn2O3, MnO2, Y2O3, ZrO2, NiO, Ni2O3, La2O3, Ce2O3, CeO2, Nd2O3, V2O3, V2O5, Cr2O3, Cr3O4, FeO, Fe2O3, Fe3O4, Ga2O3, Ag2O, In2O3, SnO, SnO2, HfO2, TaO2, Ta2O5, PbO, Pb2O3, Pb3O4, PbO2, RuO2, PdO, Ir2O3, IrO2, PtO, PtO2, Tl2O3, GaN, and mixtures of two or more of these.

[0073] The protective film 2 is preferably formed to cover 80% or more, more preferably 90% or more, and particularly preferably 100% of the first main surface of the substrate 1. When an optical element such as a diffraction grating is manufactured using the laminate 10, it is preferable that at least the pattern formation region on the first main surface of the substrate 1 is covered with the protective film 2.

[0074] The protective film 2 described above is preferably a single layer. The thickness of the protective film 2 is not particularly restricted, but for example, it can be 5 nm or more and 20 nm or less, more preferably 15 nm or less, and even more preferably 12 nm or less. By setting the thickness of the protective film 2 to 5 nm or more, when etching the thin film formed on the laminate 10, the substrate 1 can be well protected from the etching material of the thin film. On the other hand, by setting the thickness of the protective film 2 to 20 nm or less, the decrease in the transmittance of the laminate 10 to visible light can be suppressed, and when removing the finally exposed protective film 2, the protective film 2 can be removed without damaging the substrate 1.

[0075] The method for forming the protective film 2 on the substrate 1 is not particularly restricted, but sputtering deposition is preferred. Sputtering deposition is preferable because it allows for the formation of a uniform film with a consistent thickness.

[0076] Furthermore, when transferring a mold pattern to a transfer target (object to be transferred) using an imprint mold made using the laminate 10 of this embodiment as a master plate, the resin (transfer target) is cured while the imprint mold is pressed against it, for example, a substrate for optical elements. In the process of curing the resin, the resin is generally cured by light irradiation or heating. In particular, when light irradiation is performed from the back side of the imprint mold (the main surface opposite the first main surface), it is preferable that the imprint mold has light transmittance. Therefore, when light irradiation is performed from the back side of the imprint mold, the region on the substrate 1 where the protective film 2 is laminated has a transmittance of, for example, 50% or more, more preferably 70% or more, for light with a wavelength of 365 nm.

[0077] Next, other embodiments of the laminate according to the present invention will be described. Figure 2 is a cross-sectional view showing the layer configuration of another embodiment of the laminate according to the present invention. As shown in Figure 2, the laminate 20 of another embodiment of the present invention comprises a substrate 1 and a protective film 2 formed on the first main surface of the substrate 1, a first film 3 on the protective film 2, and an etching mask film 4 on the first film 3.

[0078] The details of the substrate 1 and the protective film 2 in this embodiment are the same as those for the laminate 10 in the previously described embodiment, so a redundant explanation will be omitted here.

[0079] <First membrane> The following describes the first membrane 3 mentioned above. The first film 3 described above becomes a thin film for pattern formation when using the laminate 20 of this embodiment to manufacture, for example, optical elements such as diffraction gratings or imprint molds.

[0080] The first film 3 is preferably provided on the surface of the protective film 2 in contact with the protective film 2. In other words, it is preferable that no other layers or films are interposed between the first film 3 and the protective film 2.

[0081] Furthermore, although the first film 3 can consist of multiple layers, it is preferable that it be a single layer. This is because if the first film 3 is a single layer, the side surfaces of the recesses obtained by etching the first film 3 can be formed into a desired cross-sectional shape without any steps along the way.

[0082] Furthermore, it is preferable that the first film 3 has a uniform composition in the film thickness direction, except for the interface with the protective film 2 and the surrounding region (first interface region), and the interface with the etching mask film 4 and the surrounding region (second interface region). The first interface region can extend, for example, from the interface between the protective film 2 and the first film 3 to a film thickness of 5 nm of the first film 3. The second interface region can extend, for example, from the interface between the etching mask film 4 and the first film 3 to a film thickness of 5 nm of the first film 3. If the first film 3 has a uniform composition in the film thickness direction, except for the first and second interface regions, the cross-section of the recess obtained by etching the first film 3 can be formed into a desired cross-sectional shape without steps in between, and the etching conditions of the first film 3 can be easily controlled. On the other hand, if it is difficult to obtain a good cross-sectional shape of the recess due to the material of the first film 3 or the dimensions of the recess, the first film 3 can be a compositionally graded film in which the composition constituting the first film 3 changes stepwise or continuously in the film thickness direction. In other words, if the cross-sectional shape of the recess can be improved, the composition of the first film 3 may change continuously or stepwise in the film thickness direction.

[0083] In this embodiment, the first film 3 can be made of a material that can be etched with a fluorine-containing gas. Any material that can be etched with such a fluorine-containing gas is acceptable and can be used without particular restrictions. Examples of fluorine-containing gases include perfluorocarbon gases such as F2 gas and CF4, hydrofluorocarbon gases such as CFH3, SF6 gas, NF3 gas, SiF4 gas, and HF gas. These fluorine-containing gases may also contain noble gases and / or oxygen. The noble gas is not particularly limited, but for example, argon (Ar) can be used. Etching with a fluorine-containing gas is preferred because it exhibits high anisotropy and can produce a good shape for the recesses.

[0084] Examples of materials that can be etched with fluorine-containing gases include silicon-containing materials. Preferably, these are materials containing silicon and at least one of oxygen and nitrogen. Specific examples of silicon-containing materials include SiO2, SiNx, Si3N4, and SiON. Materials containing titanium are also preferred. Specific examples of titanium-containing materials include TiO2. Other materials containing niobium (Nb), such as Nb2O5, can also be used.

[0085] Furthermore, if the protective film 2 has high resistance to chlorine-containing gases, the first film 3 can also be made of a material that can be etched with chlorine-containing gases. Any material that can be etched with chlorine-containing gases can be used without any particular restrictions. For example, materials containing aluminum or materials containing hafnium can be used. Examples of materials containing aluminum include Al2O3 and aluminum silicate (Al2O3). x Si y Examples include HfO, HfSiO, and HfAlO. Materials containing hafnium include HfO, HfSiO, and HfAlO, with the composition ratio adjusted as appropriate.

[0086] When etching the first film 3 with a fluorine-containing gas, the etching selectivity ratio of the first film 3 to the protective film 2 is preferably 2.5 or higher, more preferably 3.0 or higher, and even more preferably 3.5 or higher.

[0087] Furthermore, when patterning the etching mask film 4 provided on the first film 3 by etching, it is preferable that the first film 3 is resistant to the etching conditions of the etching mask film 4 in order to prevent damage to the first film 3. As will be described later, the etching mask film 4 is preferably made of a material containing chromium, for example. When patterning the etching mask film 4 made of a chromium-containing material, the etching gas usually used is a gas containing chlorine (for example, Cl2, SiCl2, CHCl3, CH2Cl2, CCl4, BCl3) or a mixed gas of at least one of the above chlorine-containing gases and oxygen. Therefore, when the etching mask film 4 is made of a chromium-containing material, it is preferable that the first film 3 is resistant to the above chlorine-containing gases or a mixed gas of at least one of the above chlorine-containing gases and oxygen.

[0088] The materials listed above as preferred materials for the first film 3, such as materials containing silicon or materials containing titanium, are materials that are resistant to the chlorine-containing gas and the mixed gas of this chlorine-containing gas and oxygen.

[0089] There are no particular restrictions on the thickness of the first film 3 described above. In short, when fabricating an optical element such as a diffraction grating using the laminate 20 of this embodiment, the thickness of the first film 3 can be designed and deposited according to the depth of the recess formed by etching the first film 3.

[0090] The method for forming the first film 3 on the protective film 2 is not particularly restricted, but sputtering deposition is preferred. Sputtering deposition is preferable because it allows for the formation of a uniform film with a consistent thickness.

[0091] <Etching mask film> The etching mask film 4 described above will be explained below. The etching mask film 4 is preferably provided on the first film 3 in contact with the first film 3. In other words, it is preferable that no other layers or films are interposed between the etching mask film 4 and the first film 3.

[0092] The etching mask film 4 functions as a hard mask film when etching (engraving) the first film 3 to form, for example, a pattern for an optical element or a pattern for an imprint mold on the first film 3. Therefore, the material of the etching mask film 4 has etching selectivity with respect to the first film 3 under the etching conditions for forming the pattern on the first film 3. As described above, since the first film 3 is etched with a fluorine-containing gas or a chlorine-containing gas, it is preferable that the etching mask film 4 is resistant to these etching conditions. In this embodiment, it is preferable that the etching mask film 4 is formed from a material containing one or more selected from, for example, chromium, tantalum, zirconium, hafnium, and tungsten. When the first film 3 is etched with a chlorine-containing gas, it is preferable that the etching mask film 4 is formed from a material that can be etched with a fluorine-containing gas, for example, SiO2, SiN, SiN x It can also be formed from silicon-containing materials such as Si3N4.

[0093] The etching mask film 4 is preferably formed from a material containing chromium, for example. When a fluorine-containing gas is used for dry etching of the first film 3, the chromium-containing material exhibits etching selectivity for the first film 3. Furthermore, the chromium-containing material is preferred because it can be easily etched with a chlorine-containing gas and has excellent processability.

[0094] Examples of materials containing chromium (Cr) (chromium-based materials) include chromium metal, chromium nitride, chromium carbide, chromium carbinite, and chromium oxide carbinite. In this case, the etching mask film 4 can be etched with a chlorine-containing gas. Preferably, the most abundant metal in the chromium-based material is chromium. Preferably, the chromium-based material contains 5 atomic percent or less of metals other than chromium, and more preferably contains no metals other than chromium. Since the etching rate when etching a chromium-based material with a chlorine-containing gas is higher than the etching rate when etching a silicon-containing material with a fluorine-containing gas, productivity can be improved by using a chromium-based material as the etching mask layer 3.

[0095] In addition to materials containing chromium, other examples include materials containing tantalum, zirconium, hafnium, tungsten, etc. (alloys, oxides, nitrides, carbides, oxynitrides, carbonitrides, oxidized nitride carbides, and similarly oxides, nitrides, carbides, oxynitrides, carbonitrides, and oxidized nitride carbides of alloys). Furthermore, materials containing tantalum are preferred because they can be easily etched with chlorine-containing gases and / or fluorine-containing gases and have excellent processability.

[0096] Such etching mask films 4 may be single-layer or multi-layer. For example, the etching mask film 4 may consist of a single layer of the chromium-based material. Alternatively, the etching mask film 4 may consist of at least an upper and lower laminated film, with the upper layer formed from the chromium-based material and the lower layer formed from a material mainly composed of tantalum (Ta). Examples of materials mainly composed of tantalum in this case include Ta compounds such as TaHf, TaZr, and TaHfZr, or materials that use these Ta compounds as a base material and add auxiliary materials such as B, Ge, Nb, Si, C, and N. Furthermore, materials mainly composed of tantalum are preferable because they can possess the necessary conductivity to prevent charge-up during electron beam lithography for forming resist patterns on the etching mask film 4 and to enable mold pattern inspection using a scanning electron microscope (SEM). The etching mask film 4 may also be a composition gradient film in which its composition changes continuously or stepwise in the film thickness direction. Of course, the examples of the configuration and materials of the etching mask film 4 are merely illustrative, and the present invention is not limited to these examples.

[0097] The thickness of the etching mask film 4 is not particularly restricted, but for example, it can be between 2 nm and 80 nm, more preferably 70 nm or less, and even more preferably 60 nm or less. By setting the thickness of the etching mask film 4 to 2 nm or more, when etching the first film 3 using the pattern of the etching mask film 4 as a mask, the pattern of the etching mask film 4 can be sufficiently preserved until the etching is complete. The thickness of the etching mask film 4 is more preferably 5 nm or more, and even more preferably 10 nm or more. On the other hand, by setting the thickness of the etching mask film 4 to 80 nm or less, the shape of the fine pattern can be improved. Furthermore, the etching mask film 4 can be removed at the end without damaging the material of the first film 3.

[0098] The method for forming the etching mask film 4 on the first film 3 is not particularly restricted, but sputtering deposition is preferred. Sputtering deposition is preferable because it can form a film with a uniform quality and a consistent film thickness.

[0099] Furthermore, the laminate 20 in this embodiment may be in a form in which a resist film, described later, is formed on the etching mask film 4.

[0100] According to the laminates 10 and 20 of the embodiments described above, when etching a thin film for pattern formation formed on a glass substrate, damage to the glass surface by the etching material to the thin film can be suppressed.

[0101] [Optical elements] Next, we will describe the optical element of the present invention that uses this laminate as a substrate. As described above, the optical element of the present invention comprises a substrate, a protective film formed on a first main surface of the substrate, and a first film formed on the protective film, the first film having a pattern including recesses, wherein the total content of lanthanum oxide, barium oxide, strontium oxide, calcium oxide, and magnesium oxide in the substrate is 0% by mass or more and 20.0% by mass or less, the silicon dioxide content in the substrate is 0% by mass or more and 50% by mass or less, and the protective film is characterized by being made of a material containing at least one selected from the group of metals consisting of scandium, manganese, yttrium, zirconium, nickel, lanthanum, cerium, neodymium, vanadium, chromium, iron, gallium, silver, indium, tin, tantalum, hafnium, lead, ruthenium, palladium, iridium, platinum, and thallium.

[0102] Figure 3 is a cross-sectional view showing one embodiment of the optical element according to the present invention. As shown in Figure 3, an optical element 30 according to one embodiment of the present invention comprises a substrate 1, a protective film 2 formed on a first main surface of the substrate 1, and a first film 3a formed on the protective film 2, wherein the first film 3a includes a pattern for an optical element (for example, a pattern for a diffraction grating) including recesses. Here, the total content of lanthanum oxide, barium oxide, strontium oxide, calcium oxide, and magnesium oxide in the substrate 1 is preferably 0% by mass or more and 20.0% by mass or less, and the silicon dioxide content of the substrate 1 is preferably 0% by mass or more and 50% by mass or less. Furthermore, the protective film 2 is preferably made of a material containing at least one selected from the group of metals consisting of scandium, manganese, yttrium, zirconium, nickel, lanthanum, cerium, neodymium, vanadium, chromium, iron, gallium, silver, indium, tin, tantalum, hafnium, lead, ruthenium, palladium, iridium, platinum, and thallium.

[0103] The details of the substrate 1 and the protective film 2 in the optical element 30 of this embodiment are the same as those for the laminate 10 in the previously described embodiment, so a redundant explanation will be omitted here. Furthermore, the details of the first film 3a in the optical element 30 of this embodiment are the same as those of the laminate 20 in the previously described embodiment, so a redundant explanation will be omitted here.

[0104] In the optical element 30 described above, the protective film 2 is formed in contact with the substrate 1. Furthermore, the first film 3a is formed in contact with the protective film 2. In this embodiment as well, the protective film 2 is formed to cover at least 80% or more of the first main surface of the substrate 1. Furthermore, in this embodiment as well, in the optical element 30, it is preferable that the region on the substrate 1 in which the protective film 2 and the first film 3a are laminated has a transmittance of 50% or more for light in the wavelength range of 400 to 700 nm.

[0105] Next, the manufacturing process of the above-mentioned optical element will be described. Figures 4(a) to 4(c) are cross-sectional views illustrating the manufacturing process of the optical element 30 according to one embodiment of the present invention. The optical element 30 of one embodiment of the present invention shown in Figures 3 and 4 can be manufactured, for example, using the laminate 20 described above.

[0106] A manufacturing process for the optical element 30 of one embodiment of the present invention includes the steps of: preparing the above-described laminate 20 and forming a desired resist pattern on the laminate 20; forming an etching mask pattern on the etching mask film 4 of the laminate 20 using the resist pattern as a mask; etching the first film 3 of the laminate 20 using the etching mask pattern as a mask; and removing the etching mask pattern.

[0107] The manufacturing process will be explained in detail below. A resist film made of, for example, a liquid photocurable resin is applied to the upper surface of the laminate 20 described above. In this case, a negative-type resist is preferred, but a positive-type resist may also be used.

[0108] Next, an optical element pattern (for example, a pattern for a diffraction grating) is laser-drawn onto the resist film. After drawing, the resist film is developed to form the resist pattern 5 (see Figure 4(a)).

[0109] Next, the laminate 20 on which the resist pattern 5 is formed is introduced into an etching apparatus, and etching is performed using an etching gas or etching solution to etch the etching mask film 4 using the resist pattern 5 as a mask. This forms an etching mask pattern 4a as shown in Figure 4(b). For example, if the etching mask film 4 is made of a chromium-based material, dry etching using the chlorine-containing gas or a mixed gas of chlorine-containing gas and oxygen, or wet etching using an etching solution containing ammonium hydrogen fluoride and hydrogen peroxide can be applied.

[0110] Here, the laminate on which the etching mask pattern 4a has been formed is temporarily removed from the etching apparatus, and the remaining resist pattern 5 is removed. However, the next step may be carried out without removing the remaining resist pattern 5. For the sake of clarity, the laminate 20 in which the etching mask pattern 4a, etc., has been formed will also be referred to as the "laminated structure" below.

[0111] Next, if, for example, the first film 3 is made of a titanium-based material that can be etched with a fluorine-based gas, the first film 3 is etched using a fluorine-based gas (such as CHF3 or CF4) with the etching mask pattern 4a as a mask until the surface of the protective film 2 is exposed, thereby forming recesses. This forms an optical element pattern (first film pattern) 3a with an uneven structure on the protective film 2, as shown in Figure 4(c). For etching the first film 3, an etching solution containing, for example, ammonium fluoride, phosphoric acid, and hydrogen peroxide may be used. Here, the remaining etching mask pattern 4a is removed using, for example, the etching gas or etching solution used when etching the etching mask film 4 described above. Thus, the optical element 30 of one embodiment of the present invention is completed.

[0112] In this embodiment, when etching the first film 3 to form a recess, the protective film 2 functions as an etching stopper. Therefore, the surface of the substrate 1 is not exposed. Consequently, even when, for example, a glass substrate with a high refractive index and low specific gravity that has low resistance to dry etching using a fluorine-based gas is used as the substrate 1, the glass surface is not exposed to the fluorine-based gas and is not damaged.

[0113] As described above, according to the laminate of the present invention (laminated structures 10 and 20 in the above embodiments), when etching a thin film (the first film 3) formed on a glass substrate (the substrate 1), damage to the glass surface from the etching material to the thin film can be suppressed. Furthermore, by using this laminate as a substrate, high-precision and high-performance optical elements can be manufactured.

[0114] In the optical element 30 in which a pattern is formed on the first film 3 as in this embodiment, the protective film 2 exposed at the bottom surface of the recesses of the pattern does not usually need to be removed. Depending on the material of the protective film 2 (chromium-based material, tantalum-based material, hafnium-based material, etc.), it is also possible to remove the exposed protective film 2 using, for example, a chlorine-based etching gas (the chlorine-containing gas mentioned above, a mixed gas of chlorine-containing gas and oxygen, etc.) or an etching solution containing ammonium hydrogen fluoride and hydrogen peroxide as an etching agent. Since the glass substrate (substrate 1) in this embodiment is resistant to this etching agent, the exposed glass surface is not damaged.

[0115] Furthermore, the protective film surface does not necessarily need to be exposed at the bottom of the recesses in the pattern formed on the first film 3, and the etching depth of the first film 3 can be appropriately adjusted according to the optical performance of the optical element being formed. Furthermore, in the optical element 30 of this embodiment, the heights of the multiple protrusions of the pattern formed on the first film 3 are the same, but this is not limited to this, and for example, the heights of these multiple protrusions may differ, such as a stepped shape. Also, at least one or more of the protrusions of the pattern formed on the first film 3 may have a slope shape in which the height changes continuously when viewed in cross-section.

[0116] [Imprint Mold] The optical element with the structure shown in Figure 3 can also be used as an imprint mold. Therefore, for example, using the laminate 20 described above, an imprint mold with a structure similar to that shown in Figure 3 can be manufactured according to the manufacturing process shown in Figure 4. In this case, the material, film thickness, etc., of the first film 3 in the laminate 20 may be appropriately changed to suit the imprint mold.

[0117] Furthermore, in the imprint mold described above, the protective film surface does not necessarily need to be exposed at the bottom of the recesses in the pattern formed on the first film 3. The etching depth of the first film 3 can be adjusted as appropriate depending on the mold pattern to be formed. Furthermore, in the imprint mold described above, the heights of the multiple protrusions of the pattern formed on the first film 3 may be the same, but the mold is not limited to this, and for example, the heights of these multiple protrusions may differ, such as a stepped shape. Also, one or more of the protrusions of the pattern formed on the first film 3 may have a slope shape in which the height changes continuously when viewed in cross-section.

[0118] The following describes optical elements and other components embedded in substrates. For example, in a laminate (see Figure 5) having a protective film made of, for example, a chromium-based material on a glass substrate 1 having the same glass composition as the substrate 1 described above, a substrate-etched type optical element (such as a diffraction grating) 40 can be created by etching the glass substrate 1 using the protective film on which a predetermined pattern 2a is formed as a mask, as an embodiment different from the optical element 30 described above. The substrate-etched type optical element (such as a diffraction grating) 40 is a glass substrate 1 on which the uneven pattern 1a is directly formed (see Figure 6).

[0119] This invention also provides invention A of the following glass substrate. (Invention A) A glass substrate having a pattern including recesses, The total content of lanthanum oxide, barium oxide, strontium oxide, calcium oxide, and magnesium oxide in the substrate is 0% by mass or more and 20.0% by mass or less. The silicon dioxide content of the substrate is 0% by mass or more and 50% by mass or less. A glass substrate characterized by the following features.

[0120] In this embodiment, it is preferable to use a glass substrate 1 with a high refractive index and low specific gravity. Therefore, the details regarding the glass composition of the glass substrate 1 are the same as in the case of the laminate 10 in the previously described embodiment.

[0121] Furthermore, the protective film in this embodiment is not particularly limited to any material that is pattern-forming and resistant to, for example, fluorine-based gases used to engrave the glass substrate 1. For example, the same material as the etching mask film 4 described above can be used for the protective film. Chromium-based materials, tantalum-based materials, and the like are particularly preferred as materials for the protective film.

[0122] Furthermore, in the above-described substrate-etched optical element 40, the etching depth of the glass substrate 1 (depth of the pattern recess) can be appropriately adjusted according to the optical performance. Also, the depths of the multiple recesses in the pattern formed on the glass substrate 1 may be the same as shown in Figure 6, but these multiple recesses can also be arranged in a stepped shape with different depths. One or more of the pattern recesses may have a slope shape in which the depth changes continuously when viewed in cross-section. Furthermore, the optical element 40 with the structure shown in Figure 6 can also be used as an imprint mold.

[0123] [Electronic devices] The present invention also provides electronic devices (for example, AR devices, projectors, in-vehicle display devices, and other video display devices) that include optical elements fabricated using the laminate of the present invention as described above. Furthermore, the present invention also provides a method for manufacturing an electronic device, which includes the steps of: preparing an imprint mold made using the laminate of the present invention described above; curing the resin while pressing the imprint mold onto a resin (transfer target) applied to a substrate for an electronic device; and separating the imprint mold from the resin.

[0124] As described in detail above, the present invention provides a laminate that can suppress damage to the glass surface from the etching material when etching a thin film formed on a glass substrate, even when using a glass substrate with a high refractive index and low specific gravity. Furthermore, by using this laminate as a substrate, the present invention can provide high-precision and high-performance imprint molds, optical elements, and electronic devices. [Examples]

[0125] The embodiments of the present invention will be described in more detail below with reference to examples. (Example 1) [Fabrication of laminates] A glass substrate with a main surface dimension of approximately 152 mm × 152 mm and a thickness of approximately 6.25 mm was prepared. In this Example 1, the total content of lanthanum oxide, barium oxide, strontium oxide, calcium oxide, and magnesium oxide was 0% by mass or more and 20.0% by mass or less, and the silicon dioxide content was 0% by mass or more and 50% by mass or less. Details of the substrate composition are shown in Table 1 below.

[0126] First, a protective film (Sc2O3 film, Sc:O=40 atoms:60 atoms) made of scandium and oxygen was formed on the above substrate with a thickness of 5 nm. This protective film was formed as follows: First, the above substrate was placed in a single-wafer RF sputtering apparatus, and the protective film was formed by reactive sputtering (RF sputtering) using an RF power supply with an Sc2O3 target and argon (Ar) gas as the sputtering gas.

[0127] Next, a first film (TiO2 film Ti:O=34 atoms:66 atoms) made of titanium and oxygen was formed on the protective film with a thickness of 60 nm. This first film was formed as follows: First, the substrate on which the protective film was deposited was placed in a single-wafer RF sputtering apparatus, and the first film was formed by reactive sputtering (RF sputtering) using an RF power supply with a TiO2 target and argon (Ar) gas as the sputtering gas.

[0128] Next, an etching mask film (CrN film Cr:N=75 atoms:25 atoms%) made of chromium and nitrogen was formed on the first film with a thickness of 25 nm. This etching mask film was formed as follows: First, the substrate on which the protective film and the first film were formed was placed in a single-wafer DC sputtering apparatus, and the etching mask film was formed by reactive sputtering (DC sputtering) using a DC power supply with a chromium (Cr) target and a mixed gas of argon (Ar), helium (He), and nitrogen (N2) as the sputtering gas. As described above, a laminate of Example 1 was fabricated by depositing the protective film, the first film, and the etching mask film on the substrate.

[0129] [Fabrication of optical elements] A negative-type resist film made of a liquid photocurable resin was applied to the etching mask film of the laminate of Example 1 described above. Next, a predetermined fine pattern (optical element pattern) was laser-drawn onto this resist film, and then the resist film was developed to form the resist pattern.

[0130] Next, the laminate on which the resist pattern was formed was introduced into a dry etching apparatus. Using a chlorine-based gas consisting of a mixed gas of chlorine (Cl2) and oxygen (O2), the etching mask film was etched using the resist pattern as a mask to form an etching mask pattern.

[0131] Here, the laminate with the etching mask pattern formed on it was removed from the dry etching apparatus, and the remaining resist pattern was removed.

[0132] Next, dry etching was performed in a dry etching apparatus using a fluorine-based gas (a gas containing CF4) to etch the first film using the etching mask pattern as a mask until the protective film surface was exposed, thereby forming recesses. In this way, as shown in Figure 3(c) above, a first film pattern (optical element pattern) with a raised and recessed structure was formed on the protective film on the upper surface of the substrate. Here, the ICP (Inductively Coupled Plasma) etching method was used. The etching conditions at this time were an ICP power of 425W as the plasma excitation power, an RF power (bias power) of 125W, and a pressure of 5mTorr. Furthermore, the remaining etching mask pattern was removed, and an optical element having multiple protrusions of the same height was fabricated on the substrate.

[0133] (Examples 2-23) Laminates of Examples 2 to 23 were fabricated in the same manner as in Example 1, except that the substrates with the glass compositions of Examples 2 to 23 shown in Tables 1 to 4 below were used, and the protective film materials of Examples 2 to 23 shown in Tables 1 to 4 below were used. The protective film, the first film, and the etching mask film were deposited on the substrate. For the deposition of the protective film, a target containing the protective film material and argon were used as the sputtering gas. Next, using the laminates of Examples 2 to 23, the first films of Examples 2 to 23 were etched using the same method and etching conditions as in Example 1 until the protective film surface was exposed, thereby forming recesses. In this way, optical elements of Examples 2 to 23, having optical element patterns with multiple protrusions of equal height on a substrate, were fabricated.

[0134] (Comparative Examples 1-6) Laminates of Comparative Examples 1 to 6 were prepared in the same manner as in Example 1, except that the substrates of Comparative Examples 1 to 6 with the glass compositions shown in Table 4 below were used, and the protective film materials of Comparative Examples 5 and 6 shown in Table 4 below were used, respectively, by depositing the protective film, the first film, and the etching mask film on the substrates. In Comparative Examples 1 to 4, the protective film was not deposited on the substrate (the protective film was omitted), and the first film and the etching mask film were deposited. For the deposition of the protective films in Comparative Examples 5 and 6, a target containing the protective film material and argon as the sputtering gas were used. Next, using the laminates of Comparative Examples 1 to 6, the first films of Comparative Examples 1 to 6 were etched using the same method and etching conditions as in Example 1 to form recesses. In this way, optical elements of Comparative Examples 1 to 6, each having an optical element pattern with multiple protrusions of equal height on a substrate, were fabricated.

[0135] (Reference example 1) A substrate with the glass composition shown in Reference Example 1 in Table 5 below was prepared. First, a protective film (CrN film Cr:N=75 atoms:25 atoms) made of chromium and nitrogen was formed on the above substrate with a thickness of 8 nm. This protective film was formed as follows: First, the above substrate was placed in a single-wafer DC sputtering apparatus, and the protective film was formed by reactive sputtering (DC sputtering) using a DC power supply with a chromium (Cr) target and a mixed gas of argon (Ar), helium (He), and nitrogen (N2) as the sputtering gas. As described above, a laminate of Reference Example 1 was fabricated by depositing the protective film on the substrate.

[0136] A resist pattern was formed on the protective film of the laminate of Reference Example 1 in the same manner as in Example 1. Next, the laminate on which the resist pattern was formed was introduced into a dry etching apparatus. Using a chlorine-based gas consisting of a mixed gas of chlorine (Cl2) and oxygen (O2), the protective film was etched using the resist pattern as a mask to form a protective film pattern. Here, the laminate with the protective film pattern was removed from the dry etching apparatus, and the remaining resist pattern was removed.

[0137] Next, dry etching was performed in a dry etching apparatus using a fluorine-based gas (a gas containing CF4) to etch the substrate using the protective film on which the above pattern was formed as a mask, thereby forming recesses of the desired depth. In this way, a glass substrate with a directly formed relief pattern was fabricated, as shown in Figure 6 above. Furthermore, the remaining protective film pattern was peeled off, and a substrate-recessed optical element with an optical element pattern having multiple recesses of the same depth was fabricated.

[0138] (Reference example 2) A laminate of Reference Example 2 was fabricated by depositing the protective film on the substrate in the same manner as in Reference Example 1, except that a substrate with the glass composition of Reference Example 2 shown in Table 5 below was used. Next, using the laminate of Reference Example 2, a pattern was formed on the protective film using the same method and etching conditions as in Reference Example 1. Then, the substrate was etched using the protective film with the pattern formed on it as a mask.

[0139] Furthermore, the glass composition substrates of Examples 1-23, Comparative Examples 1-6, and Reference Example 1 all met the requirement that the total content of lanthanum oxide, barium oxide, strontium oxide, calcium oxide, and magnesium oxide was between 0% by mass and 20.0% by mass, and that the silicon dioxide content was between 0% by mass and 50% by mass. On the other hand, the glass composition substrate of Reference Example 2 did not meet the requirement that the total content of lanthanum oxide, barium oxide, strontium oxide, calcium oxide, and magnesium oxide was between 0% by mass and 20.0% by mass.

[0140] [Table 1]

[0141] [Table 2]

[0142] [Table 3]

[0143] [Table 4]

[0144] [Table 5]

[0145] <Rating> By observing the cross-sections of the optical elements obtained in Examples 1-23, Comparative Examples 1-6, and Reference Examples 1 and 2 using a scanning electron microscope, we confirmed whether or not there was any damage to the exposed surface at the bottom of the recesses of the formed patterns.

[0146] <Evaluation Results> In Examples 1 to 23 of the present invention, even when the first film was etched to form recesses until the protective film surface was exposed, the exposed surface at the bottom of the recesses in the pattern formed by the etching of the first film was the protective film. Therefore, the substrate surface was not damaged.

[0147] On the other hand, in Comparative Examples 1 to 4, in which optical elements were fabricated using a laminate without a protective film on the upper surface of the substrate, when the first film was etched until the substrate surface was exposed to form recesses, the exposed surface at the bottom of the recesses in the pattern formed by the etching of the first film was the substrate. As a result, the substrate surface was damaged by exposure to the etching gas of the first film. Furthermore, in Comparative Examples 5 and 6, in which optical elements were fabricated using laminates in which the protective film was formed from a material different from that of the protective film of the present invention, when the first film was etched to form a recess, the exposed protective film was also etched. As a result, the exposed substrate surface was also damaged by exposure to the etching gas of the first film. This was thought to be because the protective films in Comparative Examples 5 and 6 had low resistance to etching of the first film.

[0148] On the other hand, in Reference Example 1, which fabricated an optical element by etching into the substrate, a patterned protective film was used as a mask, and by etching the glass substrate with a fluorine-based gas, it was possible to form a textured pattern with a good cross-sectional shape and surface roughness at the bottom of the recesses. This also shows that the substrate of Reference Example 1 can be easily etched using a fluorine-based gas. Furthermore, in Reference Example 2, which used a substrate with a different glass composition than Reference Example 1, the etching of the substrate hardly progressed, and it was not possible to form recesses with the desired depth. [Explanation of symbols]

[0149] 1 circuit board 2 Protective film 3. First film (thin film for pattern formation) 4 Etching mask film 5 Resist Patterns 10, 20 laminated 30, 40 optical elements

Claims

1. circuit board and The substrate has a protective film formed on the first main surface, In the aforementioned substrate, the total content of lanthanum oxide, barium oxide, strontium oxide, calcium oxide, and magnesium oxide is 0% by mass or more and 20.0% by mass or less. The silicon dioxide content of the substrate is 0% by mass or more and 50% by mass or less. The protective film is made of a material containing at least one metal selected from the group consisting of scandium, manganese, yttrium, zirconium, nickel, lanthanum, cerium, neodymium, vanadium, chromium, iron, gallium, silver, indium, tin, tantalum, hafnium, lead, ruthenium, palladium, iridium, platinum, and thallium. A laminate characterized by the following features.

2. The laminate according to claim 1, characterized in that the protective film contains oxygen or nitrogen.

3. The laminate according to claim 1 or 2, characterized in that the protective film is formed in contact with the first main surface.

4. The laminate according to claim 1 or 2, characterized in that it has a first film on the protective film.

5. The laminate according to claim 1 or 2, characterized in that the silicon dioxide content of the substrate is 10% by mass or less.

6. The laminate according to claim 1 or 2, characterized in that the protective film is formed to cover 80% or more of the first main surface of the substrate.

7. The laminate according to claim 1 or 2, characterized in that the region on the substrate on which the protective film is laminated has a transmittance of 50% or more for light in the wavelength range of 400 nm to 700 nm.

8. An imprint mold characterized in that the first film according to claim 4 has a pattern including recesses formed on it.

9. circuit board and A protective film formed on the first main surface of the substrate, It has a pattern including recesses and a first film formed on the protective film, In the aforementioned substrate, the total content of lanthanum oxide, barium oxide, strontium oxide, calcium oxide, and magnesium oxide is 0% by mass or more and 20.0% by mass or less. The silicon dioxide content of the substrate is 0% by mass or more and 50% by mass or less. The protective film is made of a material containing at least one metal selected from the group consisting of scandium, manganese, yttrium, zirconium, nickel, lanthanum, cerium, neodymium, vanadium, chromium, iron, gallium, silver, indium, tin, tantalum, hafnium, lead, ruthenium, palladium, iridium, platinum, and thallium. An optical element characterized by the following features.

10. The optical element according to claim 9, characterized in that the protective film contains oxygen or nitrogen.

11. The optical element according to claim 9 or 10, characterized in that the protective film is formed in contact with the first main surface.

12. The optical element according to claim 9 or 10, characterized in that the silicon dioxide content of the substrate is 10% by mass or less.

13. The optical element according to claim 9 or 10, characterized in that the protective film is formed to cover 80% or more of the first main surface of the substrate.

14. The optical element according to claim 9 or 10, characterized in that the region on the substrate on which the protective film and the first film are laminated has a transmittance of 50% or more for light in the wavelength range of 400 to 700 nm.

15. An electronic device characterized by including the optical element described in claim 9 or 10.

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