Laminate, imprint mold, optical element, and electronic device

Abstract

Provided is a laminate with which damage to a glass surface can be suppressed when etching a thin film formed on a glass substrate.　This laminate has 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 0-20.0 mass%. The content of silicon dioxide in the substrate is 0-50 mass%. The protective film contains at least one selected from the metal 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.

Description

Laminates, imprint molds, optical elements, and electronic devices

[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.

[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 and 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.

[0004] Japanese Patent Publication No. 2010-243787, International Publication No. 2017 / 018375

[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.

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

[0010] (Configuration 1) A laminate comprising a substrate and a protective film formed on the 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. (Configuration 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] (Configuration 4) A laminate according to any one of Configurations 1 to 3, characterized in that it has a first film on the protective film. (Configuration 5) A 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] (Configuration 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. (Configuration 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 characterized in that a pattern including recesses 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, and a first film formed on the protective 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 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, characterized in that the protective film contains oxygen or nitrogen. (Configuration 11) The optical element according to Configuration 9 or 10, characterized in that the protective film is formed in contact with the first main surface.

[0017] (Configuration 12) An optical element according to any one of Configurations 9 to 11, characterized in that the silicon dioxide content of the substrate is 10% by mass or less. (Configuration 13) An optical element according to any one of Configurations 9 to 12, characterized in that the protective film is formed 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] (Configuration 15) An electronic device characterized by including an optical element described in any of Configurations 9 to 14.

[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.

[0021] This is a cross-sectional view showing the layer configuration of one embodiment of the laminate according to the present invention. This is a cross-sectional view showing the layer configuration of another embodiment of the laminate according to the present invention. This is a cross-sectional view showing one embodiment of the optical element according to the present invention. (a) to (c) are cross-sectional views illustrating the manufacturing process of the optical element according to one embodiment of the present invention. This is a cross-sectional view showing the layer configuration of the laminate used in the manufacture of the optical element of another embodiment. This is a cross-sectional view showing the optical element of another embodiment.

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

[0023] [Laminate] The laminate of the present invention will be described below. 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 (first main surface and second main surface) and an end surface located between the two main surfaces. The substrate 1 is made of lanthanum oxide (La ２ O ３ ), barium oxide (BaO), strontium oxide (SrO), calcium oxide (CaO), magnesium oxide (MgO), and silicon dioxide (SiO2) ２ The substrate 1 may be a glass substrate containing at least one of the following: lanthanum oxide (La ２ O ３), the total content of barium oxide (BaO), strontium oxide (SrO), calcium oxide (CaO) and magnesium oxide (MgO) is preferably 0% by mass or more and 20.0% by mass or less. Further, the content of silicon dioxide (SiO ２ ) in the substrate 1 is preferably 0% by mass or more and 50% by mass or less. The substrate 1 may not contain any of lanthanum oxide (La ２ O ３ ), barium oxide (BaO), strontium oxide (SrO), calcium oxide (CaO), magnesium oxide (MgO) and silicon dioxide (SiO ２ ). Further, in order to better exhibit the effects of the present invention, the substrate 1 is preferably a glass substrate with a high refractive index and a low specific gravity. Hereinafter, as an embodiment of the substrate 1, the case where the substrate is the above glass substrate will be described.

[0026] <Glass substrate (substrate 1)> In this specification, unless otherwise specified, the glass composition is expressed on an oxide basis. Here, the "glass composition on an oxide basis" means a glass composition obtained by converting all glass raw materials into oxides existing in the glass when melted. The total content of all glass components (excluding Sb (Sb ２ O ３ ), Ce (CeO ２ ), and Sn (SnO ２ ) added as fining agents) expressed on an oxide basis is 100% by mass. The notation of each glass component follows the convention, and is described as SiO ２ , TiO ２ , etc.

[0027] The content of the glass component can be quantified by known methods, such as inductively coupled plasma atomic emission spectrometry (ICP-AES), inductively coupled plasma mass spectrometry (ICP-MS), etc. Further, in this specification, the content of a constituent component being 0 (zero) % by mass means that this constituent component is substantially not contained, and it is allowed that the component is contained at an inevitable impurity level.

[0028] The following describes the glass components contained in the substrate 1. As described above, in the present invention, the La contained in the substrate 1 ２ O ３ The total content of BaO, SrO, CaO, and MgO is preferably 0% by mass or more and 20.0% by mass or less. These components have the effect of lowering the melting temperature of the glass and improving the thermal stability of the glass. ２ O ３ By setting the total content of BaO, SrO, CaO, and MgO to a 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, La ２ O ３ The total content of 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 % of the total amount of glass based on oxides, the F content is preferably less than 1.0%, 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 substance of component F, expressed as a mass percentage, assuming that all the cationic components constituting the glass are oxides bonded with oxygen in sufficient quantities to balance their charge, and that the total amount of substance of the glass made of these oxides is 100%.

[0032] Furthermore, in this embodiment, the SiO of the substrate 1 ２ The content is preferably 0% by mass or more and 50% by mass or less. SiO ２ By setting the content within this range, a glass substrate with a high refractive index, high stability, and low specific gravity can be obtained. ２SiO is a network-forming component of glass, improving the thermal stability, chemical durability, and weather resistance of glass, increasing the viscosity of molten glass, and making it easier to mold. ２ By having the content within the above range, the desired refractive index can be obtained. In the present invention, SiO ２ The 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 is SiO ２ It does not have to include. In this embodiment, the substrate 1 is a glass substrate with a high refractive index and low specific gravity.

[0033] In this embodiment, La of the substrate 1 ２ O ３ The content 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. ２ O ３ This can increase the refractive index of glass. ２ O ３ By keeping the 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 is La ２ O ３ It does not have to be included.

[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 having the BaO content within the above range, an increase in specific gravity can be suppressed and a desired refractive index can be obtained. In addition, a decrease in the thermal stability and devitrification resistance of the glass can be suppressed. Note that the substrate 1 does not 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 having 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 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. The substrate 1 does not necessarily have 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, P of the substrate 1 ２ O ５ The content is preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 40% by mass or less. Also, P of substrate 1 ２ O ５ The content is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more. ２ O ５ It is a network-forming component of glass and is effective because it contains a large amount of highly dispersed components in the glass.２ O ５ By setting the content within the above range, it becomes easier to obtain the desired refractive index, and the melting temperature can be controlled within an appropriate range.

[0039] In this embodiment, Li of the substrate 1 ２ The O content 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 is Li ２ It does not need to contain O. Li ２ By setting the O content within the above range, the melting temperature can be lowered, the specific gravity can be reduced, and the thermal stability of the glass can be improved. ２ O contributes to a higher refractive index among alkaline components. Li ２ By keeping the O content within the above range, the 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 Na of the substrate 1 ２ The O content 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. The substrate 1 is Na ２ It does not need to contain O. ２ O can lower the melting temperature, improve the thermal stability of the glass, and contribute to lowering the specific gravity. Na ２ By having an O content within the above range, the desired refractive index can be obtained.

[0041] In this embodiment, K of the substrate 1 ２ The O content 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 is K ２ It does not have to contain O. K ２ O can lower the melting temperature, improve the thermal stability of the glass, and contribute to lowering the specific gravity. ２ By having an O content within the above range, the desired refractive index can be obtained.

[0042] In this embodiment, the TiO of the substrate 1２ The content is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. Also, the TiO of the substrate 1 ２ The content is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more. ２ This greatly contributes to higher refractive index and higher dispersion. Also, TiO ２ Among the components that increase the refractive index, it contributes to lowering the specific gravity. TiO ２ By keeping the content within the above range, it is possible to achieve both a high refractive index and a low specific gravity, and chemical durability can also be improved. ２ By setting the content within the above range, it is possible to suppress the decrease in transparency (clouding) of the glass due to crystal formation within the glass during the process of obtaining the glass substrate. It is also possible to suppress the discoloration of the glass.

[0043] In this embodiment, the Nb of the substrate 1 ２ O ５ The content is preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less. Also, the Nb of the substrate 1 ２ O ５ The content is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more. Nb ２ O ５ This contributes to higher refractive index and higher dispersion. Nb ２ O ５ By setting the content within the above range, the thermal stability and chemical durability of the glass can be improved. Nb ２ O ５ By keeping the 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 WO of the substrate 1 ３ The content 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 is WO ３ It does not have to include it. WO ３can increase the refractive index of the glass. WO ３ By having the content within the above range, an increase in specific gravity and a decrease in thermal stability can be suppressed.

[0045] In this embodiment, the B ２ O ３ 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 may not contain B ２ O ３ . B ２ O ３ can increase the refractive index of the glass. By having the content of B ２ O ３ within the above range, coloring of the glass and an increase in specific gravity 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 may not contain ZnO. ZnO can lower the melting temperature of the glass and improve thermal stability and devitrification resistance. By having the ZnO content within the above range, an increase in specific gravity can be suppressed, and a desired refractive index can be obtained. Also, a decrease in the thermal stability of the glass and a decrease in devitrification resistance can be suppressed.

[0047] In this embodiment, the Bi ２ O ３ 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 may not contain Bi ２ O ３ . Bi ２ O ３ can increase the refractive index of the glass. By having the content of Bi ２ O ３ within the above range, coloring of the glass and an increase in specific gravity can be suppressed.

[0048] In this embodiment, the Al ２ O ３The content is preferably 2.0% by mass or less, more preferably 1.5% by mass or less, still more preferably 1.0% by mass or less, and particularly preferably 0.5% by mass or less. Note that the substrate 1 may not contain Al ２ O ３ Al ２ O ３ is a network-forming component of the glass and can improve the thermal stability, chemical durability, and weather resistance of the glass. By having the content of Al ２ O ３ within the above range, a desired refractive index can be obtained. In addition, it is possible to suppress a decrease in the devitrification resistance of the glass due to an increase in the melting temperature and a decrease in the thermal stability due to an increase in the glass transition temperature Tg.

[0049] In this embodiment, the content of ZrO ２ in the substrate 1 is preferably 10% by mass or less, more preferably 5% by mass or less, still more preferably 3% by mass or less, and particularly preferably 1% by mass or less. Note that the substrate 1 may not contain ZrO ２ ZrO ２ can increase the refractive index of the glass and improve the thermal stability and devitrification resistance. By having the content of ZrO ２ within the above range, an increase in specific gravity, an increase in melting temperature, and a decrease in the thermal stability of the glass can be suppressed. <​​​​​​​​​​​​​​​​​​​​​​​​​), Sn(SnO ２ Sb is a substance that can be optionally added as a clarifying agent. ２ O ３ , CEO ２ and SnO ２ Sb when the total content of all other glass components is assumed to be 100% by mass. ２ O ３ , CEO ２ and SnO ２ The content of each is preferably 2% by mass or less, but may be 0%.

[0052] The refractive index n of the substrate 1 with respect to the d line (wavelength 587.56 nm) is also specified. ｄ The refractive index n of the substrate 1 with respect to the d line is preferably 1.5 or higher, more preferably 1.7 or higher, and even more preferably 1.95 or higher. ｄ The Abbe number ν of the substrate 1 is preferably 2.5 or less, more preferably 2.3 or less, and even more preferably 2.2 or less. ｄ The Abbe number ν of the substrate 1 is preferably 20.0 or less, more preferably 19.0 or less, and even more preferably 18.0 or less. ｄ The Abbe number ν is preferably 15.0 or higher, more preferably 16.0 or higher. ｄ is, ν ｄ = (n ｄ -1) / (n Ｆ -n Ｃ ) can be calculated as follows: where n Ｆ The refractive index of the above substrate 1 with respect to the F line (wavelength 486.13 nm), n Ｃ This refers to the refractive index of the substrate 1 with respect to the C line (wavelength 656.27 nm).

[0053] The substrate 1 in this embodiment is a high-refractive-index glass, yet its specific gravity is not high. If the specific gravity of the glass can be reduced, the weight of the lens can be reduced. On the other hand, if the specific gravity is too low, it may lead to a decrease in thermal stability.

[0054] Therefore, in the substrate 1 according to this 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 mainly 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 substrate 1 described above may 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 known glass manufacturing methods. For example, several types of compounds may be blended and thoroughly mixed to form a batch raw material, which may then be roughly melted in a quartz crucible 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 may 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, the protective film will be described. 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 transmittance of light from the imprint mold, optical elements, 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), it is preferable that the protective film 2 contains 80 atomic percent or less of a metal selected from the metal group, 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 1 is engraved using a protective film 2 with a pattern formed on it as a mask to produce a substrate-engraved optical element, 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 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 percent or less, more preferably 60 atomic percent or less, and even more preferably 55 atomic percent 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 of the protective film 2 is specifically, for example, Sc ２ O ３ , MnO, Mn２ O ４ , Mn ２ O ３ , MnO ２ , Y ２ O ３ , ZrO ２ NiO, Ni ２ O ３ , La ２ O ３ Ce ２ O ３ , CeO ２ , Nd ２ O ３ , V ２ O ３ , V ２ O ５ , Cr ２ O ３ , Cr ３ O ４ FeO, Fe ２ O ３ , Fe ３ O ４ , Ga ２ O ３ Ag ２ O, In ２ O ３ ,SnO,SnO ２ , HfO ２ ,TaO ２ , Ta ２ O ５ , PbO, Pb ２ O ３ , Pb ３ O ４ , PbO ２ RuO ２ ,PdO,Ir ２ O ３ ,IrO ２ , PtO, PtO ２ ,Tl ２ O ３ GaN and mixtures of two or more of these are preferred examples.

[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 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 making the thickness of the protective film 2 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 making the thickness of the protective film 2 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, another embodiment 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 the other embodiment of the present invention comprises a substrate 1, 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 of the laminate 10 in the previously described embodiment, so a redundant explanation will be omitted here.

[0079] <First Film> The first film 3 described above will now be explained. The first film 3 is 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 surface of the recess 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 the middle, 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 F ２ Gas, CF ４ Perfluorocarbon gases such as CFH ３ Hydrofluorocarbon gases such as SF ６ Gas, NF ３ Gas, SiF ４ Examples include gases and HF gases. These fluorine-containing gases may further 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 recesses.

[0084] Examples of materials that can be etched with fluorine-containing gases include materials containing silicon. Preferably, the material contains silicon and at least one of oxygen and nitrogen. A specific example of a silicon-containing material is SiO ２ , SiNx and Si ３ N ４ Examples include SiO2. Materials containing titanium are also preferred. Specific examples of titanium-containing materials include, for example, TiO2. ２ These are some examples. Other examples include Nb ２ O ５ Materials containing niobium (Nb), such as the one shown, 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. As for materials containing aluminum, Al ２ O ３ , aluminum silicate (Al ｘ Si ｙ Examples include HfO, HfSiO, and HfAlO, and the composition ratio is 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 is usually a gas containing chlorine (for example, Cl ２ SiCl ２ , CHCl ３ ,CH ２ Cl ２ , CCl ４ , BCl ３ A mixed gas of oxygen and at least one of the above-mentioned chlorine-containing gases is used. Therefore, if 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-mentioned chlorine-containing gas or a mixed gas of oxygen and at least one of the above-mentioned chlorine-containing gases.

[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] The thickness of the first film 3 described above does not need to be particularly restricted. In short, when manufacturing 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 now be explained. 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, SiO ２ , SION, SIN ｘ and Si ３ N ４ It can be formed from a silicon-containing material such as the following.

[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. The metal most abundant in the chromium-based material is preferably chromium. The metals contained in the chromium-based material preferably include 5 atomic percent or less of metals other than chromium, and more preferably contain no metals other than chromium. 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, so 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 a resist pattern 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 2 nm or more and 80 nm or less, 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. In addition, 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 Element] Next, an optical element of the present invention using this laminate as a substrate will be described. As described above, the optical element of the present invention comprises a substrate, a protective film formed on the 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 an optical element according to the present invention. As shown in Figure 3, the optical element 30 of 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 of the laminate 10 in the previously described embodiment, so a redundant explanation will be omitted here. Similarly, 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. The first film 3a is also formed in contact with the protective film 2. In this embodiment as well, the protective film 2 is formed to cover at least 80% of the first main surface of the substrate 1. In this embodiment as well, in the optical element 30, it is preferable that the region on the substrate 1 where 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 of the optical element described above will be explained. Figures 4A-C (a) to (c) are cross-sectional views illustrating the manufacturing process of the optical element 30 of one embodiment of the present invention. The optical element 30 of one embodiment of the present invention shown in Figures 3 and 4A-C can be manufactured, for example, using the laminate 20 described above.

[0106] The 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 described 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 4A(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 4B(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. At this point, the next step may be carried out without removing the remaining resist pattern 5. For the sake of explanation, the laminate 20 in which the etching mask pattern 4a etc. has been formed will also be referred to as the "laminated laminate" below.

[0111] Next, for example, if the first film 3 is formed of a titanium-based material that can be etched with a fluorine-based gas, the fluorine-based gas (CHF ３ CF ４ Using the etching mask pattern 4a as a mask, the first film 3 is etched until the surface of the protective film 2 is exposed, thereby forming recesses. This forms an optical element pattern (first film pattern) 3a with a recessed structure on the protective film 2, as shown in Figure 4C(c). For etching the first film 3, an etching solution containing, for example, ammonium fluoride, phosphoric acid, and hydrogen peroxide may be used. The remaining etching mask pattern 4a is then removed using, for example, the etching gas or etching solution used when etching the etching mask film 4. Thus, an 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 laminates 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 in 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. Also, in the optical element 30 of this embodiment, the heights of the multiple protrusions in 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 can be different, such as a stepped shape. In addition, at least one or more of the protrusions in 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 the same structure as that shown in Figure 3 can be manufactured according to the manufacturing process shown in Figures 4A-C described above. 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. Also, in the imprint mold described above, the heights of the multiple protrusions in the pattern formed on the first film 3 may be the same, but this is not limited to this, and for example, these multiple protrusions may have different heights, such as a stepped shape. In addition, one or more of the protrusions in 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 substrate-etched optical elements, etc. 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 optical element (diffraction grating, etc.) 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 optical element (diffraction grating, etc.) 40 is a glass substrate 1 on which an uneven pattern 1a is directly formed (see Figure 6).

[0119] The present invention also provides the following invention A for a glass substrate: (Invention A) A glass substrate 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, and the content of silicon dioxide in the substrate is 0% by mass or more and 50% by mass or less.

[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 as long as it is a material that can form a pattern and is 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. In addition, 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 image display devices) that include optical elements made 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 as described above; curing a resin (transfer target) while pressing the imprint mold onto 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.

[0125] Embodiments of the present invention will be described in more detail below with reference to examples. (Example 1) [Preparation of Laminate] A substrate made of glass with a main surface dimension of approximately 152 mm x approximately 152 mm and a thickness of approximately 6.25 mm was prepared. In the substrate used 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 content of silicon dioxide 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 (Sc) made of scandium and oxygen is applied to the substrate. ２ O ３ A film Sc:O = 40 atomic%:60 atomic%) was formed to 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 Sc ２ O ３ A protective film was formed using a target and argon (Ar) gas as the sputtering gas by reactive sputtering (RF sputtering) powered by an RF power supply.

[0127] Next, a first film (TiO) made of titanium and oxygen is placed on top of the protective film. ２ A film Ti:O = 34 atomic%:66 atomic%) was formed to 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 TiO ２ A first film was formed using a target and argon (Ar) gas as the sputtering gas by reactive sputtering (RF sputtering) powered by an RF power supply.

[0128] Next, an etching mask film (CrN film Cr:N = 75 atomic%:25 atomic%) made of chromium and nitrogen was formed on the first film to 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 a chromium (Cr) target and argon (Ar), helium (He), and nitrogen (N) were used as sputtering gases. ２An etching mask film was formed by reactive sputtering (DC sputtering) using a mixed gas of ) and a DC power supply. In this manner, a laminate of Example 1 was fabricated by forming 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 above resist pattern was formed was introduced into a dry etching apparatus. ２ ) and oxygen (O ２ Using a chlorine-based gas consisting of a mixed gas of the above, the etching mask film was etched using the above 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, in the dry etching apparatus, a fluorine-based gas (CF ４ By performing dry etching using a gas containing the above etching mask pattern, the first film was etched using the etching mask pattern as a mask until the surface of the protective film was exposed, thereby forming recesses. In this way, as shown in Figure 3(c) above, a first film pattern (optical element pattern) with a bumpy 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 peeled off, and an optical element having an optical element pattern with multiple bumps of the same height was fabricated on the substrate.

[0133] (Examples 2-23) Laminates of Examples 2-23 were fabricated in the same manner as in Example 1, except that the substrates of Examples 2-23 with the glass compositions shown in Tables 1-4 below were used, and the protective film materials of Examples 2-23 shown in Tables 1-4 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 these laminates of Examples 2-23, the first film of Examples 2-23 was 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 2-23, having optical element patterns with multiple protrusions of equal height on the substrate, were fabricated.

[0134] (Comparative Examples 1-6) Laminates of Comparative Examples 1-6 were prepared in the same manner as in Example 1, except that the substrates of Comparative Examples 1-6 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 1-4, 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 film 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 1-6, the first film of Comparative Examples 1-6 was etched using the same method and etching conditions as in Example 1 to form recesses. In this way, optical elements of Comparative Examples 1-6, having optical element patterns with multiple protrusions of equal height on the substrate, were prepared.

[0135] (Reference Example 1) A substrate with the glass composition of Reference Example 1 shown in Table 5 below was prepared. First, a protective film (CrN film Cr:N = 75 atomic%:25 atomic%) made of chromium and nitrogen was formed on the substrate to a thickness of 8 nm. This protective film was formed as follows. First, the substrate was placed in a single-wafer DC sputtering apparatus, and a chromium (Cr) target and argon (Ar), helium (He), and nitrogen (N) were used as sputtering gases.２ A protective film was formed by reactive sputtering (DC sputtering) using a mixed gas of ) and a DC power supply. In this way, 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. Chlorine (Cl ２ ) and oxygen (O ２ Using a chlorine-based gas consisting of a mixed gas of ), the protective film was etched using the resist pattern as a mask to form a protective film pattern. At this point, the laminate with the protective film pattern was removed from the dry etching apparatus, and the remaining resist pattern was removed.

[0137] Next, in the dry etching apparatus, a fluorine-based gas (CF ４ By performing dry etching using a gas containing the above-mentioned material, the substrate was etched using the protective film on which the above-mentioned pattern was formed as a mask to form recesses of the desired depth. In this way, a glass substrate on which the uneven pattern was directly formed was manufactured, as shown in Figure 6 above. Furthermore, the remaining protective film pattern was peeled off to manufacture a substrate-recessed type optical element having an optical element pattern with multiple recesses of the same depth.

[0138] (Reference Example 2) A laminate of Reference Example 2 was prepared by depositing the protective film on a 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, a pattern was formed on the protective film using this laminate of Reference Example 2 in the same manner 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 to 23, Comparative Examples 1 to 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 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.

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[0145] <Evaluation> The cross-sections of each optical element from Examples 1 to 23, Comparative Examples 1 to 6, and Reference Examples 1 and 2 were observed with a scanning electron microscope to confirm 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 laminates 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 made of a material different from the protective film material of the present invention, when the first film was etched to form recesses, 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 by the first film.

[0148] On the other hand, in Reference Example 1, which fabricated an optical element of the substrate-etched type, a good uneven pattern with a good cross-sectional shape and surface roughness at the bottom of the recess was formed by using a fluorine-based gas to etch the glass substrate using a protective film on which a pattern was formed as a mask. 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.

[0149] 1. Substrate 2. Protective film 3. First film (thin film for pattern formation) 4. Etching mask film 5. Resist pattern 10, 20. Laminate 30, 40. Optical element

Claims

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.

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. An optical element comprising: a substrate; a protective film formed on a first main surface of the substrate; and a first film formed on the protective 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 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.

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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