Manufacturing method of optical tools

Abstract

To allow for manufacturing an optical tool with high dimensional precision by reducing the dimensional conversion difference while producing oblique grooves on the optical tool.SOLUTION: A method of manufacturing an optical tool 10 with oblique protrusions is provided, the method comprising etching a mask 16 having a sloped surface rising obliquely from a surface of a base material by applying an etching source to the base material 11 at a tilt angle of the sloped surface to form an oblique protrusion 20 extending from the inside of the base material 11 to the surface thereof at the tilt angle.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing an optical device by a patterning method that minimizes the dimensional conversion error of oblique groove processing by etching. [Background technology]

[0002] Diffractive optical elements and optical filters have the property of irradiating light in a direction different from that of the incident light or transmitting only incident light within a certain wavelength range, and are used for camera focusing, headsets for virtual reality (VR), color filters, etc. The surfaces of some diffractive optical elements and optical filters are formed with projections and recesses, and diffract light due to the difference in refractive index between the materials of the recesses and projections. For example, JP 2012-098548 A (Patent Document 1) describes a diffractive optical element using materials with different refractive indexes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-098548 A Summary of the Invention [Problem to be solved by the invention]

[0004] For optical tools such as diffractive optical elements and optical filters, there is a demand for optical tools that meet various requirements depending on the application, such as reflecting light in a wide wavelength range, limiting transmitted light, etc., and there is a demand for diffractive optical elements whose surface shape, particularly the size and shape of unevenness, is strictly controlled. The present invention has been developed to meet these demands. [Means for solving the problem]

[0005] According to one aspect of the present disclosure, there is provided a method for manufacturing an optical device having an inclined convex portion, the method comprising: applying an etching source to a mask having an inclined surface rising obliquely from a surface of a substrate, at an inclination angle of the inclined surface, and etching the substrate, thereby forming an inclined convex portion along the inclination angle from inside the substrate toward the surface.

[0006] In a method for manufacturing an optical device having an inclined convex portion, an etching source is applied to a substrate at the inclination angle of a mask having an inclined surface rising obliquely from the substrate surface, so that dimensional conversion error, which occurs when the mask casts a shadow and the actual groove dimensions differ from the desired groove dimensions, can be reduced. This improves the accuracy of dimensional control and prevents a decrease in yield. Furthermore, since an optical device can be obtained that forms an inclined convex portion along the inclination angle from the inside of the substrate toward the surface, the obtained optical device can be used for VR applications and the like that require the substrate surface to have unevenness with inclined surfaces.

[0007] According to another aspect of the present disclosure, the method for manufacturing an optical tool may be such that the mask has a substantially truncated cone shape with the base material side as a bottom surface. Since the mask is shaped like a generally truncated cone with the bottom surface facing the substrate, the irradiation angle of the etching source can be adjusted to the inclination angle of the mask, making it possible to engrave the desired grooves.

[0008] According to another aspect of the present disclosure, there is provided a method for manufacturing an optical device, the method including a step of forming the mask by performing anisotropic etching on a coating material that covers a core material patterned on the base material. Since the method includes the step of forming the mask by performing anisotropic etching on a coating material that covers a core material patterned on the base material, a mask having an inclined surface with respect to the base material can be formed.

[0009] In one aspect of the present disclosure, the method for manufacturing an optical device may be such that the tilt angle is adjusted by the amount of film formation of the coating material and the height of the core material. Since the inclination angle is adjusted by adjusting the amount of film formed of the coating material and the height of the core material, the inclination angle can be controlled, and an optical device having an inclined groove or inclined convex portion with a desired inclination angle can be obtained.

[0010] According to one aspect of the present disclosure, the method for producing an optical tool may be such that the substrate is a glass substrate. Since the substrate is a glass substrate, the method is suitable for producing an optical device that takes advantage of the transparency of glass. Effect of the Invention

[0011] According to the present invention, the dimensional conversion error in machining oblique grooves into optical tools can be reduced, and optical tools with high dimensional accuracy can be manufactured. [Brief description of the drawings]

[0012] [Figure 1] 3 is a schematic cross-sectional view showing a state in which a resist has been formed in the manufacturing process of the optical tool of the present invention. FIG. [Diagram 2] 3A to 3C are schematic cross-sectional views showing a state in which the optical tool is covered with a covering material during the manufacturing process of the optical tool of the present invention. [Diagram 3] 3A to 3C are schematic cross-sectional views showing a state in which a mask having a desired shape has been formed during the manufacturing process of the optical tool of the present invention. [Figure 4] FIG. 4 is an explanatory diagram for explaining the relationship between the width and height of a mask using an example in which the base angle is 60 degrees, FIG. 4(A) being a schematic cross-sectional view, and FIG. 4(B) being a schematic plan view. [Diagram 5] FIG. 5 is an explanatory diagram for explaining the relationship between the width and height of a mask in an example where the base angle is 30 degrees, and is a schematic cross-sectional view equivalent to FIG. 4(A) in FIG. [Figure 6] FIG. 1 is an explanatory diagram illustrating a gap between masks. [Figure 7] FIG. 11 is another explanatory diagram for explaining the gap between the masks. [Figure 8]3 is a schematic cross-sectional view showing a state in which an etching source is irradiated along a slope of a mask during a manufacturing process of the optical tool of the present invention. FIG. [Figure 9] 3A to 3C are schematic cross-sectional views illustrating the shape of an optical tool obtained during the manufacturing process of the optical tool of the present invention. [Figure 10] 1 is a schematic plan view of an optical tool according to the present invention. [Figure 11] FIG. 11(A) is a schematic plan view of another optical device of the present invention, and FIG. 11(B) is a schematic sectional view of the same. [Figure 12] 4, showing a mask used in another method for producing an optical tool according to the present invention. FIG. [Figure 13] FIG. 13 is an explanatory diagram for explaining that a dimensional conversion difference is large in a method using a conventional mask. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The present invention relates to a technique for obtaining a shape of a recessed portion from the outermost surface of an optical tool such as a diffractive optical element or an optical filter having an uneven surface, in the form of an inclined groove deeply dug obliquely from the outermost surface. The detailed description will be given below.

[0014] In general, to form an inclined groove, an etching source such as plasma, ion beam, or GCIB is incident at an angle to the substrate to be etched. However, there is a potential problem of dimensional conversion error, in which the width dimension of the actually processed groove differs from the desired groove. That is, as shown in the schematic cross-sectional view of FIG. 13, when an etching source 2 is applied to a mask material 1 at an angle, the mask material 1 for patterning casts a shadow, resulting in a difference in width between the desired groove and the actually processed groove, and the effect of a decrease in yield due to deterioration of dimensional control has been considered as an issue. The present invention provides a method for fabricating an inclined groove with little dimensional conversion error.

[0015] <First embodiment>: An optical tool according to the present embodiment and a method for manufacturing the same will be described below. Figures 1 to 3, 8, and 9 are schematic cross-sectional views illustrating the manufacturing process of this optical tool 10. First, as shown in Fig. 1, a resist 12 is patterned on a base material 11 such as a glass substrate by a method such as photolithography or RIE (step 1). It is preferable to use an organic material such as a synthetic resin for the resist 12, because this is because it is easy to pattern and has excellent adhesion to the coating material 14. The height of the resist 12 will be described later.

[0016] Next, a mask material is formed. As shown in Fig. 2, resist 12 is used as core material 13, and a Ni film or the like is coated on the top and side surfaces of core material 13 by electroless plating, vapor deposition or other techniques to form coating material 14 (step 2). If this coating material 14 is a Ni film, it is preferable because it has a large selectivity with respect to glass substrate 11 and resist 12. However, materials other than Ni that have a large selectivity with respect to glass substrate 11 and resist 12 can also be used.

[0017] Then, the mask skin material 15 is formed into a desired shape as shown in Fig. 3 (Step 3). The mask skin material 15 is formed by anisotropically etching the covering material 14 in a direction perpendicular to the surface of the base material 11 using RIE or the like. This anisotropic etching allows the covering material 14 to be scraped to have an inclined surface, and the mask skin material 15 produced by this anisotropic etching can be combined with the core material 13 to obtain a mask 16 of a desired shape.

[0018] FIG. 4 shows a case where the inclination angle (base angle) of the mask 16, whose cross section is approximately trapezoidal, is designed to be 60 degrees, and FIG. 5 shows a case where the inclination angle (base angle) of the mask 16 is designed to be 30 degrees. In the case of the mask 16 with an inclination angle of 60 degrees, when the length L of the width from the core material 13 at the bottom of the mask 16 is "1", the ideal height of the mask 16 is "√3". Therefore, in the above step 1, the height of the resist 12 that becomes the core material 13 is formed to be "√3". Also, in the above step 2, the Ni film is formed so that the width of the mask skin material 15 in the mask 16 is "1". Then, in step 3, the coating material 14 is etched until the base material 11 appears, so that the coating material 14 attached to the upper surface of the core material 13 is peeled off, and the coating material 14 attached to the side surface of the core material 13 also has a rounded shape. In this case, the upper surface of the core material 13 and the upper surface of the mask skin material 15 are over-etched, so that the height is slightly recessed from "√3". In this way, the side surface of the core material 13 is covered with the mask skin material 15, and a mask 16 having a substantially truncated cone shape with a cross section that is trapezoidal and an inclination angle of 60 degrees is obtained.

[0019] Similarly, a mask 16 with an inclination angle of 30 degrees as shown in FIG. 5 can also be formed. In this case, when the length L of the width from the core material 13 at the bottom surface of the mask 16 is "1", the ideal height of the mask 16 is "1 / √3". Therefore, in the above step 1, the height of the resist 12 that becomes the core material 13 is formed to be "1 / √3". In addition, in the above step 2, the coating material 14 made of a Ni film is formed so that the width of the mask skin material 15 is "1". Then, in step 3, the coating material 14 is etched until the base material 11 appears, thereby obtaining a mask 16 with an approximately truncated cone shape with an inclination angle of 30 degrees and a trapezoidal cross section as shown in FIG. 5.

[0020] From the above, the masks 16 constituting the mask pattern 17 and the intervals 18 therebetween are designed as follows. That is, as shown in FIG. 6, the length of "B" in the mask 16 is adjusted by the width of the core material 13, and the lengths of "A" and "C" are adjusted by the deposition amount of the coating material 14 that becomes the mask skin material 15. The length of "D", which is the interval 18 between the masks 16, is adjusted by the pitch of the core material 13. By carrying out such adjustments and executing the above steps 1 to 3, the desired mask pattern 17 can be obtained. Therefore, for example, when forming a mask pattern 17 in which the width of one mask 16 is "1" and the interval 18 is "1" as shown in FIG. 7, the dimensions of each part can be adjusted so that A+B+C=D in FIG. 6.

[0021] Next, the substrate 11 is etched using the mask pattern 17 thus obtained. That is, when an etching source (etchant) is irradiated obliquely onto the surface of the substrate 11 at the inclination angle of the inclined surface of the mask 16 (step 4), an inclined groove 19 formed at a desired angle and opening width can be obtained as shown in Fig. 8. Here, the size of the groove, such as the depth and width of the groove, can be adjusted by appropriately selecting the processing time in etching, the type of etching source, etc., but in a preferred embodiment, the groove width can be 50 to 500 nm, and the groove depth can be 50 to 500 nm.

[0022] Finally, the mask 16 is removed by wet etching or dry etching (step 5), thereby obtaining the optical device 10 having obliquely inclined recesses as shown in Fig. 9. Fig. 10 is a schematic plan view of the optical device 10 of Fig. 9, and as shown in this figure, the optical device 10 is obtained in a shape in which a plurality of oblique cylindrical inclined protrusions 20 (see particularly the partially enlarged schematic view R of Fig. 10) protrude from the surface 11a of the etched base material 11. In other words, the optical device 10 has inclined grooves 19 recessed obliquely from the outermost surface 11b of the base material 11.

[0023] The arrangement of the inclined convex portions 20 shown in Figure 10 is just one example, and by adjusting the resist 12 and forming the core material 13, it is possible to form an optical device 10 in which the inclined convex portions 20 are arranged randomly or in other arrangements. Alternatively, although an example has been shown in which the mask 16 is formed into a substantially truncated cone shape, the mask can also be formed into a block shape that produces the same cross section as in Fig. 3 even in the depth direction of Fig. 3. By forming such a mask, an optical device 10a as shown in Fig. 11 is obtained. In this optical device 10a, the inclined convex portions 20 are formed into columnar shapes extending parallel to the planar direction of the substrate, and the concave portions sandwiched between the inclined convex portions 20 are also formed into columnar shapes.

[0024] <Second embodiment>: In the optical tool and the manufacturing method thereof of this embodiment, the mask 16 is formed by thermal melting rather than etching. In the above embodiment, the covering material 14 is formed by a metal coating (Ni coating) by electroless plating or vapor deposition, but instead, a thermoplastic resin film is formed by coating or spraying. Hot air with a temperature higher than the glass transition point (Tg) of the resin is blown onto the top side of the mask 16 to melt the top of the mask, thereby manufacturing a mask with the desired inclined surface. This method also makes it possible to obtain an optical tool 10 having an inclined convex portion 20.

[0025] <Third embodiment>: In the optical tool and the manufacturing method thereof of this embodiment, the shape of the mask 16 to be produced and the method of forming the same are different from those of the previous examples. In the above embodiment, the top shape of the mask 16 is tapered with chamfers on all four sides, but in this embodiment, the mask is etched by sputter etching with Ar or the like in one direction, such as diagonally upward, of the core material 12, after being covered with the covering material 14. By doing so, a shape is obtained in which the upper part of the mask 16 is cut by an oblique plane. It is preferable to use an organic material for the covering material 14, as this is easily cut.

[0026] In the method of this embodiment, whereas in the previous embodiments, anisotropic etching is performed perpendicular to the surface of the substrate 11 to form the mask 16, anisotropic etching is performed obliquely to the surface of the substrate 11, resulting in a mask 16a having the shape shown in FIG. 12.

[0027] The above-described embodiments are examples of the present invention, and modifications of the embodiments, addition of known technologies, combinations, etc. may be made without departing from the spirit of the present invention, and such technologies are also included in the scope of the present invention. [Explanation of symbols]

[0028] 10,10a optical equipment 11 Substrate (glass substrate, etc.) 11a Etched surface of substrate 11b Outer surface of substrate 12 Resist 13 Core material 14 Covering material 15 Mask covering material 16,16a Mask 17 Mask Pattern 18 intervals 19 Slant groove 20 Inclined convex part R Partially enlarged schematic diagram

Claims

1. A method for manufacturing an optical tool having an inclined convex portion, comprising the steps of: forming a mask on the surface of a substrate, the mask having an inclined surface rising obliquely from the surface of the substrate and having a substantially truncated cone shape with the substrate side as a bottom surface; and applying an etching source to the substrate at an inclination angle of the inclined surface to perform etching, thereby forming an inclined convex portion along the inclination angle from the inside of the substrate toward the substrate surface, A method for manufacturing an optical device, characterized in that in the step of forming the mask, a core material that has been patterned and has its height adjusted is covered with a coating material whose film formation amount is adjusted, and anisotropic etching is performed to adjust the tilt angle.

2. 2. The method for manufacturing an optical tool according to claim 1, wherein the substrate is a glass substrate.

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