JP2004271558A - Polarizing optical element and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a polarizing optical element as an "inorganic material product" having a high-precision surface three-dimensional structure at low cost with good reproductivity by simplifying processes of production. <P>SOLUTION: A metal mold after release processing is coated with ultraviolet-ray setting resin 16, and a light-transmissive product substrate 2 after silane coupling processing is pressed against the resin; and the reverse surface side of the product substrate 2 is irradiated with uniform ultraviolet rays to set the ultraviolet-ray setting type resin layer 16 and then the metal mold is released. The shape of t he resin layer 16 is transferred to the product substrate 2 by dry etching. A TiN film is formed to about 8 nm on the surface where the pattern of the product substrate 2 is formed, an AL-CVD film is formed thereupon to 0.12 μm, and a groove is completely filled. After reflow processing is carried out for five minutes at 350°C, an aluminum film is etched back to the surface of the product substrate to manufacture a polarizing optical element having a conductive element array of aluminum buried in a quartz substrate. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a product exhibiting an optical function by performing ultrafine processing on a surface thereof, and a method for producing the same. Particularly, a large number of products arranged at equal intervals on a surface of an inorganic dielectric substrate at a pitch shorter than the wavelength of incident light. The present invention relates to an inorganic polarizing optical element (an optical element utilizing an electromagnetic wave component among the properties of light) provided with an array composed of the strip-shaped conductive elements, and a method of manufacturing the same.
[0002]
[Prior art]
The polarizing optical element includes an "organic material product" using an organic sheet material, and an "inorganic material product" in which thin metal wires are arranged in an array on an inorganic material substrate.
The “organic material product” is made of an organic polymer material whose main component is PVA (polyvinyl alcohol). The manufacturing method is as follows. After impregnating and mixing an iodine material or an organic dye into a PVA film material, stretching it in an X direction or an XY direction, and joining a sandwich structure with an organic film material such as PVA from above and below. Therefore, it is also called a dichroic polarizer. Since it is composed of an organic polymer material, the operating temperature is limited to 100 ° C. or less.
[0003]
As an example, a “polarizing plate” made of PVA material is inexpensive and performs well as a portable liquid crystal polarizing plate. An optical product that is used for large-screen display devices and optically condenses high-intensity lamp light and irradiates high-density light vertically to the liquid crystal panel, and the temperature near the liquid crystal panel rises to about 120 ° C. A cooling fan or the like is provided to avoid the temperature rise.) The polarizing plate cannot be used due to heat resistance and durability problems. In particular, in this application, the function is deteriorated when light having a short wavelength is irradiated for a long time.
[0004]
As a countermeasure, efficient cooling is important. (1) Installation of a cooling fan, (2) Installation of a black matrix (BM) which is a heat absorption source of the panel, and adoption of a reflective film for the BM film. (3) The panel frame pair is made of metal, and (4) Sapphire glass with high thermal conductivity (40 times that of glass) is used for supporting equipment. This is a weak point of the device.
[0005]
`` Inorganic material product '' is proposed to solve the above problem, in which metal thin wires are arranged in an array on an inorganic material substrate, and the surface of the inorganic dielectric substrate has a wavelength smaller than the wavelength of light used. 2. Description of the Related Art A polarizing optical element including an array of a large number of strip-shaped conductive elements arranged at equal intervals at a short pitch is known (see Patent Documents 1 to 5).
[0006]
FIG. 4 schematically shows such a polarization optical element, in which a number of strip-shaped conductive elements 22 having a width w are arranged in parallel on a dielectric substrate 20 at a pitch p shorter than the wavelength of incident light. Array. When the incident light 24 is incident on the polarization optical element at an angle of θ from the perpendicular so that the incident surface is orthogonal to the conductive element 22, the polarization optical element has a polarization vector of the polarization component of the incident light 24 that is orthogonal to the incident surface. It functions as a polarization optical element in which the polarized light component is reflected light 26 and the polarized light component having a polarization vector parallel to the plane of incidence is transmitted light 28.
[0007]
Such an “inorganic material product” is manufactured using X-ray exposure and a lift-off method, and an aluminum wire is formed as a conductive element 22 on a glass material.
[0008]
The following methods A) and B) have been proposed as methods for producing an ultrafine structure.
A) A method in which a direct drawing method using an electron beam, a laser beam, an ion beam, or the like, optical lithography, and a dry etching technique are combined (see Non-Patent Document 1).
B) Regarding a method for manufacturing a multifunctional diffractive optical element, the "effective refractive index method" in which the phase modulation amount of a light wave is controlled by a combination of elements having a structure characterized by a filling factor having a fixed relief depth (binary level). (See Non-Patent Document 2).
[0009]
[Patent Document 1]
JP-T-2003-502708
[Patent Document 2]
U.S. Pat. No. 6,208,463
[Patent Document 3]
U.S. Pat. No. 6,122,103
[Patent Document 4]
U.S. Pat. No. 6,243,199
[Patent Document 5]
U.S. Pat. No. 5,458,084
[Non-patent document 1]
"Applied Physics", Vol. 68, No. 6, (1999) p. See 633-638
[Non-patent document 2]
“27th Optical Symposium” Lecture Nos. 9, 10, 11: Proceedings of Lectures (2001) 25-36
[0010]
[Problems to be solved by the invention]
In conventional polarizing optical elements of “inorganic material products”, aluminum conductive elements are formed on the surface of the glass substrate, so the adhesiveness between the glass substrate material and the aluminum conductive elements is poor, so they are easily peeled off and durable. There is a problem.
In addition, there is also a problem that since the surface has fine irregularities, if touched by hand, dirt enters the concave portion and cannot be removed, making it difficult to handle.
Accordingly, a first object of the present invention is to provide a polarizing optical element of “inorganic material product” which is durable and easy to handle.
[0011]
As a method for forming an ultra-fine three-dimensional structure having an L / S (line and space) smaller than the optical wavelength to be used, which is the object of the present invention, the above-mentioned methods A) and B) are used. Among them, in the method A, although there is a report on the production research of the diffractive optical element, the cross-sectional structure is tapered, and the pitch is only about 0.7 times (0.7λ) the used wavelength, and is large. Further, there are the following problems.
[0012]
(A) In a mask exposure method using a laser beam, an ion beam, or X-rays, there is a limit to the L (line) width that can be formed (a limit that L smaller than the wavelength of light used for exposure cannot be formed). A sufficiently small hyperfine structure cannot be manufactured.
[0013]
(B) The direct writing method using an electron beam has the following problems (1) to (6).
{Circle around (1)} An enormous writing time is required for writing over a wide area (about 10 to 15 hours for a 500 μm × 500 μm square).
{Circle around (2)} The drawing range is limited to 500 μm × 500 μm, and it is necessary to connect the effective drawing regions.
{Circle around (3)} In this case, the joining accuracy σ is about 15 nm. When drawing is performed only once, it is possible to perform drawing with higher accuracy. However, when drawing is repeated many times, the joining accuracy is deteriorated for the following reasons a) to d).
a) The filament current fluctuates during writing due to long-time writing.
b) Long-time drawing lowers the drawing position accuracy.
c) The filament itself deteriorates.
e) Performance of drawing apparatus itself (depending on apparatus design)
(4) Poor reproducibility in drawing.
{Circle around (5)} Defects are likely to occur during drawing.
(6) An apparatus having a high-precision control technique is required, and the drawing apparatus is expensive (1 billion to 1.5 billion yen / unit).
[0014]
Therefore, as a method of manufacturing a mass-produced product that requires stable supply at a low price, a direct writing method using an electron beam cannot be used, and there has been no practical example.
Accordingly, a second object of the present invention is to provide a method for simplifying the production process and producing a polarizing optical element of “inorganic material product” having a high-precision surface three-dimensional structure with good reproducibility and at low cost. It is to be.
[0015]
[Means for Solving the Problems]
The polarizing optical element of the present invention has the same width and the same depth on a flat surface of an inorganic dielectric substrate having a flat surface that is transparent to incident light and has a pitch shorter than the wavelength of the incident light. At least one array of a large number of strip-shaped conductive elements arranged at intervals and embedded so that the surface is flush with the flat surface of the substrate is provided.
[0016]
In the present invention, since the conductive element is embedded in the substrate, the heat resistance is good, and the conductive element does not peel off from the substrate, so that the durability is excellent. In addition, since the surface is flat and has no irregularities, even if it is touched by hand, it can be easily removed, and handling becomes easy.
[0017]
The manufacturing method of the present invention for manufacturing this polarizing optical element includes the following steps (A) to (F) in that order.
(A) A step of manufacturing a mold having a fine shape composed of a number of convex arrays having the same width and the same height on a flat surface and arranged at equal intervals at a pitch shorter than the wavelength of the incident light. .
(B) a step of pressing a product substrate against the surface of the mold via a curable resin and transferring the surface shape of the mold to the resin on the product substrate;
(C) a step of curing the resin.
(D) a step of peeling the resin from the mold while the resin is bonded to the product substrate.
(E) a step of transferring the shape transferred to the resin to the product substrate by a dry etching method.
(F) a step of filling a recess formed in the surface of the product substrate with a metal in the step (E).
[0018]
The content of this manufacturing method can be roughly divided into the following two stages. (1) to form an L / S ultra-fine three-dimensional structure on a desired substrate; and (2) to fill the groove of the three-dimensional structure with a metal film.
[0019]
In the present invention, a method is employed in which the ultrafine three-dimensional structure of L / S is transferred to a resin using a mold, and the transferred shape is transferred to a product substrate. In the process of manufacturing a mold, it is necessary to use an expensive drawing apparatus, and it takes a long time to draw, but once a high-precision mold is manufactured, a product is manufactured using this mold. There is no need to draw directly for each mass-produced product, the production process is simplified, and the polarizing optical element can be manufactured with good reproducibility and at low cost.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
It is preferable that an antireflection film is formed on the surface of the substrate in which the strip-shaped conductive element array is embedded and on the surface on the opposite side. Thus, a polarizing element having good adhesion to the ultrafine structure, low cost, high heat resistance and corrosion resistance, and high optical efficiency can be obtained.
[0021]
A conductive layer connected to the band-shaped conductive element may be embedded in a region other than the region where the band-shaped conductive element array is formed. In this case, when the surface of the polarizing optical element in the strip-shaped conductive element array generates heat, the heat is easily released. If a heat sink is brought into contact with the conductive layer, the heat dissipation effect is further enhanced.
[0022]
In the manufacturing method, it is preferable to perform a mold release treatment on the mold surface before pressing the product substrate on the mold surface via the resin in the step (B). An example of the mold release treatment on the mold surface is to form a metal thin film on the mold surface, and this mold release treatment dramatically increases the mold transferability of the mold, and at the same time allows accurate transfer. In addition, the releasability is facilitated, and the life of the mold is dramatically improved.
[0023]
As the release treatment, it is preferable to further perform a surface treatment on the metal thin film with a layer containing a finely structured fluororesin.
When the product substrate is pressed via the resin to the mold surface subjected to the release treatment, it is preferable to perform a primer surface treatment between the resin and the product substrate surface to improve the adhesion between them. . Thereby, in the peeling step, the peeling is selectively performed from the mold side, and the resin cracking (part of the resin remaining in the mold at the time of peeling) is sharply reduced. As a result, shape transferability in the next step is improved.
[0024]
As the resin for transferring the inverted shape of the surface shape of the mold, an ultraviolet curable resin or a thermosetting resin can be used.
The use of an ultraviolet curable resin as the resin has the following advantages. (1) Curing at room temperature is possible. (2) Since it can be applied in liquid form, it has good fluidity and can prevent the generation of bubbles and the like. {Circle around (3)} Since the curing can be performed by uniformly irradiating the ultraviolet light, the curing can be performed uniformly. (4) Can be cured in a short time. As a result, the mold surface shape can be easily and accurately transferred.
[0025]
Even when a thermosetting resin is used as the resin, by uniformly curing, the mold surface shape can be accurately transferred in the same manner as the ultraviolet curable resin. As the thermosetting resin, a resin used for manufacturing a plastic spectacle lens or a contact lens can be used.
[0026]
When using an ultraviolet-curable resin as a resin for transferring an inverted shape of the surface shape of the mold, as a method of curing the ultraviolet-curable resin, at least one of the mold and the product substrate is made of an ultraviolet-transmissive material. In addition, in the curing process of the ultraviolet-curable resin, the ultraviolet-curable resin is irradiated with ultraviolet rays through a mold or a product substrate of the ultraviolet-transmitting material, or both, so as to uniformly cure the ultraviolet-curable resin. Is preferred. By uniformly curing the ultraviolet curing resin, the shape transferability of the mold is dramatically increased, and accurate transfer can be performed.
[0027]
When a thermosetting resin is used as the resin to transfer the inverted shape of the mold surface, as a method of curing the thermosetting resin, the mold and the product substrate are fixed in a positioned state, and the resin injection port is separately provided. Provide. In the curing step of the thermosetting resin, it is desirable to heat and cure the resin while gradually heating so that the heat is uniformly distributed throughout the mold.
[0028]
Generally, the resin shrinks upon curing. Therefore, the shrinkage amount is determined in advance, and in the shape transfer step to the mold base material by dry etching of the photosensitive material, the shape of the mold base material is corrected to be deeper in consideration of the shrinkage amount portion. It is preferable to perform the processing, and to quantitatively control the flat surface of the mold and the flat surface of the product substrate so that they are parallel to each other and the gap therebetween is small. This makes it possible to correct the curing shrinkage amount.
[0029]
One preferable method for forming the fine shape of the mold surface is a method including the following steps (G) to (I) in that order.
(G) a step of applying a photosensitive material (resist) on the surface of the mold base material on which the fine shape is to be formed.
(H) a step of drawing a desired shape on the photosensitive material with an electron beam (EB), and then developing the desired shape on the photosensitive material.
(I) a step of transferring the shape of the photosensitive material to a mold base material by a dry etching method.
[0030]
By drawing a desired shape with an electron beam, a desired shape can be manufactured with high accuracy in one process.
If the shape of the photosensitive material is transferred to the mold base material by dry etching, the resist shape, which is a soft material, can be transferred to the hard mold material.
[0031]
In this case, the mold base material needs to be a material that can be dry-etched, and such a material is selected from the group consisting of a metal material, a glass material, a ceramic material, a semiconductor material, a plastic material, and a hard rubber material. One kind can be used.
[0032]
Generally, the mold base material is a flat substrate. And a fine shape is formed on the surface on the plane.
When a photosensitive material for electron beam drawing is used to form a photosensitive material pattern on the surface of a mold base material when making a mold, the photosensitive material for electron beam drawing is a positive resist and a negative resist. However, when applying a positive resist as a fine structure manufacturing method and drawing by an electron beam drawing method, the drawing reproducibility is good, and control of electron leakage and the like is easy and controllable. There is an advantage that it is easy.
[0033]
When manufacturing a mold, a desired shape is deeply transferred in a depth direction (as an aspect ratio becomes large) in a dry etching step in a step of transferring a shape of a photosensitive material to a mold base material by a dry etching method. In order to achieve this, it is preferable to change the selection ratio stepwise or continuously. As described above, by changing the selection ratio stepwise or continuously, a desired shape can be deeply obtained at the time of transfer. Here, the “mold” is an article having a base shape, and means “a master having a base shape to be transferred”. Although not described in detail in the present case, based on the above “mold” (mother type), “metal mold production” (sister type) is performed by electroforming (although the shape is inverted), and this is referred to as “transfer mold”. It can also be used as a "mold". In this case, there is no particular limitation on a metal or alloy material as long as the material can be plated.
[0034]
When transferring the shape transferred to the resin to the product substrate by the dry etching method, in order to form a desired shape on the product substrate, the etching selectivity between the resin and the product substrate in the dry etching is stepwise or continuously. Preferably, it is changed. By adjusting the selection ratio, the shape in the depth direction can be corrected, and the image can be transferred to a desired deep shape. Also, the flatness of the substrate surface can be ensured by interrupting the etching process (for ultra-fine transfer) halfway, leaving the resin layer slightly on the substrate surface, and then removing the resin layer together with the seed layer.
[0035]
As a manufacturing method of filling a groove portion of a three-dimensional ultrafine structure formed on a product substrate with a metal film, W and Cu materials are proposed as a 0.1 μm (= 100 nm) through-hole filling technology in a semiconductor integrated circuit manufacturing field. Have been. However, in the polarizing optical element of the present invention, (a) the line width of the line may be further reduced to 100 nm or less, and (b) an AL (aluminum) material exhibiting high reflectivity performance is preferably used. (C) required solid filling performance, (d) no air bubbles must be present in the filling material, and so on. Sometimes it just doesn't work.
[0036]
Therefore, in a preferred method of the present invention, as a method of filling an aluminum material as a preferred metal for the manufactured ultrafine structure, an AL-CVD method is used to form a film in the ultrafine structure densely and with good coverage. .
[0037]
In the AL-CVD method, first, a seed layer (seed layer) for growing an AL film by a reduction reaction is formed by a sputtering method in an ultra-vacuum. This is a seed layer made of Ti or TiN material. By this method, TiN and Ti as seed layers are formed even in ultra-fine holes in the target substrate.
[0038]
If necessary, the above-described etching step for ultrafine transfer may be interrupted in the middle, the resin layer may be slightly left on the substrate surface, and then the step of removing the resin layer may be performed here.
Next, a special AL-CVD gas is heated and evaporated to be introduced into a dedicated CVD film forming apparatus (chamber). In the apparatus, since the surface of the product substrate is heated to a substrate temperature at which the reduction CVD reaction sufficiently occurs, a metal AL film is formed (deposited) on the substrate surface based on the surface of the seed layer. The film is formed until the hole is completely filled.
[0039]
The surface completely filled with aluminum is slightly over-deposited (so thicker than the depth of the hole). Therefore, the entire surface of the glass substrate is covered with aluminum. However, the entire surface of the substrate is not formed at a uniform rate during the growth of aluminum. Therefore, when microscopically observed, the morphology of the surface is rough in the order of several nm to several tens nm. In order to remove this roughness, it is preferable to pass through a reflow process. This step is a heating reflow step of flattening the surface of the metal film by heating to a temperature at which the metal is melted in a vacuum chamber without exposing to the atmosphere after the metal CVD film is formed. By heating and reflowing, the aluminum on the substrate surface is flattened parallel to the substrate surface and perpendicular to the gravity by the surface force and gravity.
[0040]
Then, CMP (Chemical Mechanical Polishing) method up to the surface of the product substrate, which has an ultrafine structure to provide a transparent transmission line surface (consisting of glass) on the substrate surface to express optical performance The surface is polished while controlling the polishing amount with high precision, or the so-called etch-back is performed in which the metal aluminum film is removed by etching in a dry etching apparatus.
[0041]
【Example】
(Example 1)
The polarization optical element shown in FIGS. 1A and 1B was manufactured. 1A is a schematic plan view, and FIG. 1B is a cross-sectional view of the conductive element array portion of FIG. 1A cut along the vertical direction. This polarizing optical element has a groove structure in which the line and space L / S formed on the surface of the synthetic quartz substrate 2 having a thickness t of 1.0 mm is 35 nm / 35 nm, the pitch P is 70 nm, and the depth D is 110 nm. The conductive elements 4 filled with aluminum are arranged in an array. The size of the substrate 2 is 25 mm × 20 mm, and the element effective range is 22 mm × 17 mm. In the array, the L / S conductive elements 4 are arranged in a regular pattern parallel to the lateral direction. L (line) indicates a portion where the aluminum film is buried, S (space) indicates a portion where the quartz surface remains, and P indicates a pitch of L + S. The number of lines is omitted. The figure shows only four conductive elements 4 in an enlarged and simplified manner.
[0042]
A few mm of the outer peripheral portion of the conductive element array has a portion without the conductive element 4 in a strip shape. In that portion, a conductive layer 5 connected to the conductive element 4 is embedded. The conductive layer 5 is the same aluminum film as the conductive element 4, and can be formed simultaneously with the conductive element 4 when forming the conductive element 4.
[0043]
An anti-reflection film 6 is formed on both front and back surfaces of the polarizing optical element. The antireflection film 6 is made of, for example, MgF ₂ Film, SiO ₂ Film and TiO ₂ It is a five-layer film including a film. The wavelength at which the antireflection film 6 has an antireflection function is in the range of 380 to 700 nm, and the transmittance is 99% or more when the transmittance of the quartz substrate is 100%.
[0044]
Hereinafter, a manufacturing procedure of the polarization optical element will be described with reference to FIGS.
Hereinafter, description will be made with reference to cross-sectional views for each process.
(A) (Step of applying a photosensitive material for an electron beam on a mold base material and drawing with an electron beam)
A silicon substrate having a diameter of 6 inches and a thickness of 1.0 mm was prepared as the mold base material 10. A photosensitive material (resist) for electron beam lithography (resist) 12 (ZEP-520, manufactured by Zeon Corporation) was applied on the surface of the mold base material 10 with a spinner at 500 rpm for 5 seconds, and then at 4000 rpm for 30 seconds. Thereafter, pre-baking was performed at 90 ° C. for 5 minutes, followed by rapid cooling. At this time, the resist film thickness was 0.14 μm.
[0045]
Next, in order to obtain an inverted shape of the shape shown in FIG. 1 (the concavo-convex shape is opposite), separately use dedicated software to input a region division, a path and a beam diameter, a dose amount, a writing time, etc., which the EB irradiation beam traces. Keep it. In the case of the present embodiment, the whole drawing area was divided into 500 μm × 500 μm square areas to create a drawing program, and these areas were joined to draw the entire area of 22 mm × 17 mm. In this case, the final product shape and the drawing shape are in an inverted relationship. It is natural that a program is produced in an inverted shape in advance.
[0046]
The mold base material 10 to which the resist 12 has been applied is set in an electron beam lithography apparatus and evacuated to a predetermined degree of vacuum. Next, the dedicated data is transferred to the control device of the drawing apparatus, and drawing is started. In this case, drawing was performed while moving the XY stage, and drawing required 48 hours.
[0047]
(B) (Development / Rinse Step) (The figure shows the cross-sectional shape of the pattern after development.)
After drawing, development was performed at 25 ° C. for 3 minutes using a developing solution (ZEP-520 developing solution). Rinse was performed and dried immediately with a nitrogen blower and spinner rotation. Post baking was performed at 120 ° C. for 5 minutes.
[0048]
(C) (a step of manufacturing a mold by dry etching using the photosensitive material 12 as a mask) (a step of performing a peeling treatment, if necessary).
The resist pattern 12a after drawing was transferred to the mold base material 10 by a dry etching method. The dry etching at this time is performed using a TCP (inductively coupled plasma) etching apparatus, ₄ : 20 sccm gas is introduced, substrate bias voltage: 500 W, upper electrode power: 1250 W, degree of vacuum 1.0 × 10 ^-3 Etching was performed for 0.5 minutes at Toor (that is, 1.5 mToor). At this time, the etching rate was 0.18 μm / min. The etching was terminated by slightly (about 0.01 μm) under-etching. That is, the resist is slightly left on the surface. The etching selectivity (the etching rate of the mold base material / the etching rate of the resist) was 1.0, and the height of the shape 14 of the mold 10a after the etching was 0.12 μm (120 nm). The surface roughness Ra was good at 0.002 μm or less. The shape height was set in consideration of the selectivity in the next step and the resin shrinkage (7%). The mold shape 14 at this time had a constant pitch and only a height of 0.9 times the shape at the time of drawing.
[0049]
To release the surface of the mold 10a, the surface was treated with a triazine thiol organic compound having a fluorine functional group. This was performed by a method called an organic plating method. Specifically, electrolytic polymerization treatment (organic plating) was performed in a solution in which fluorinated SFTT (super fine triazine thiol) was dissolved in a solvent to form a fluorine-based organic thin film on the mold surface. The fluorinated SFTT is obtained by fluorinating a side chain of triazine thiol, which is one of organic sulfur compounds. As for the number n of fluorine molecules, the water repellent effect (stripping effect) was highest when n = 7, and thus a film was formed at 100 ° under these conditions.
[0050]
(D) (Step of applying resin on the mold pattern and pressing the product substrate from above)
The mold 10a subjected to the release treatment was set below, and 1 cc of an acrylic resin (GRANDIC RC-8720, manufactured by Dainippon Ink Co., Ltd.) was applied thereon as an ultraviolet curing resin 16 which is a preferable resin. This mold 10a is set in a special bonding machine, and a flat substrate 2 (a product made by Shin-Etsu Quartz Co., Ltd .: synthetic quartz sprocilil) of a light-transmitting product substrate which has been subjected to a silane coupling treatment (adhesion improving treatment) in another step in advance Slowly press the silane coupling-treated surface of P-20). At this time, bonding was performed by an automatic bonding machine in which the descending speed and the degree of parallelism between the mold and the product substrate (so that the interval was 50 nm or less) were controlled so as not to generate bubbles in the ultraviolet curable resin 16.
Next, the resin was slowly pushed up from the mold 10 side to the product substrate 2 side to remove an extra ultraviolet curable resin 16 at the time of shape transfer.
[0051]
(E) (Step of curing the resin by irradiating with ultraviolet rays and then peeling off)
The ultraviolet curable resin layer 16 was cured by irradiating 3000 mJ of uniform ultraviolet light from the back side of the product substrate 2. At this time, the thickness of the ultraviolet-curable resin layer 16 (the distance between the top of the ultraviolet-curable resin layer 16 and the product substrate 2) was 0.05 μm or less. Naturally, the maximum thickness of the ultraviolet curable resin layer 16 is “pattern depth: 0.12” + “0.05 or less” = 0.17 μm or less.
[0052]
(F) (Step of separating mold from product substrate)
Next, in order to separate the ultraviolet-curable resin layer 16 from the surface of the mold 10a while keeping the ultraviolet-curable resin layer 16 bonded to the product substrate 2, the mold material silicon substrate 10a is deformed into a slightly convex shape using a jig, and is parallel to each other. Peeling was performed while maintaining the state.
When the transfer shape of the resin layer 16 on the surface of the product substrate 2 was measured, the height of the optical element portion was reduced to 0.11 μm (110 nm). This is because the resin layer 16 hardened and shrunk, and the hardening shrinkage was about 8.5% on average.
[0053]
(G) (Step of transferring resin shape to product substrate by dry etching)
Next, the transfer shape of the resin layer 16 on the product substrate 2 was transferred in the same manner as described above. The dry etching at this time is performed using a TCP (inductively coupled plasma) etching apparatus, ₄ : 20 sccm gas is introduced, substrate bias voltage: 500 W, upper electrode power: 1250 W, degree of vacuum 1.0 × 10 ^-3 Etching was performed for 0.5 minutes at Toor (that is, 1.5 mToor). At this time, the etching rate was 0.10 μm / min. The etching was terminated by slightly (about 0.04 μm) under-etching. That is, the resin is slightly left on the surface. The etching selectivity (etching rate of the product substrate / etching rate of the resin layer) was 1.0, and the shape height of the product substrate 2 after the etching was 0.11 μm (110 nm). The surface roughness Ra was good at 0.002 μm or less.
[0054]
The etched shape was measured for L / S dimensions and level difference using a side-length SEM device. As the optical element shape in this intermediate step, a groove structure 4a having L / S = 35/35 nm, P = 70 nm, and depth: D = 110 nm was produced on the surface of the synthetic quartz material of the product substrate 2.
[0055]
(H) (Step of filling the groove with AL by AL-CVD method ((1) Ti or TiN seed layer + (2) AL-CVD))
(These steps were carried out in a vacuum apparatus having a number of vacuum chambers and an integrated reaction tank requiring a transfer system in the center.)
A TiN film having a thickness of about 8 nm was formed on the surface of the product substrate 2 on which the pattern was formed using a normal sputtering apparatus.
[0056]
Next, reverse sputtering was performed in Ar gas for 0.5 minutes in a separate chamber as necessary for the purpose of surface activation. In this step, the surface of the TiN film is activated.
[0057]
Then, while heating the substrate to 125 ° C., MPA (1-methylpyrrolidine alane: decomposed into an allan gas containing pyrrolidine gas and aluminum by a decomposition reaction. Aluminum is deposited on the substrate surface from the allan gas) gas is flowed at 10 SCCM for 1 minute. Under the conditions of a film forming pressure of 47 Pa, an AL-CVD film was formed to a thickness of 0.12 μm.
[0058]
At this time, the grooves were completely filled, but the surface roughness of the aluminum was rough, so that reflow was performed at 350 ° C. for 5 minutes to make the aluminum surface flat, uniform, dense, and improved in adhesion. At this time, the film thickness of aluminum (from the quartz substrate surface) was 10 nm. The surface roughness of the aluminum after this treatment was good at Ra = 3 nm or less.
[0059]
(I) (Step of removing the metal AL film over-deposited on the quartz surface by the etch-back method until the quartz of the product substrate appears on the surface)
The aluminum film after aluminum film formation and reflow was etched to the surface of the quartz substrate of the product substrate by an etch back (dry etching) method. The dry etching at this time is performed using a TCP (inductively coupled plasma) etching apparatus, ₄ Substrate bias voltage: 300 W, upper electrode power: 1250 W, substrate temperature: 20 ° C., degree of vacuum 1.0 × 10 while introducing a gas of 7 sccm, Ar: 10 sccm, and BCL: 3 sccm. ^-3 Etching was performed at Toor (that is, 1.0 mToor) for 0.5 minutes. At this time, the etching rate including the aluminum and TiN films was 20 nm / min (10 nm / 0.5 min). Since the etching was stopped using the end point detector, the etching was terminated by just etching the surface of the quartz substrate. That is, aluminum and quartz are exposed on the surface. The surface roughness was good when Ra = 0.002 μm or less.
[0060]
(J) An antireflection film is formed on both surfaces of the quartz substrate 2.
Although it has proceeded in the form of a substrate, finally, it is cut into individual polarizing optical elements by a dicing device and cut off for commercialization.
The pattern size and optical performance of the obtained polarizing optical element are evaluated.
In the product inspection, the cross-sectional shape of the sample was evaluated and the size was measured with a length-measuring SEM.
According to the manufacturing method of the above example, a polarization characteristic of transmittance: 64% and contrast: 683 (λ = 450 nm) was obtained as designed.
[0061]
【The invention's effect】
The polarizing optical element of the present invention has the same width and the same depth on a flat surface of an inorganic dielectric substrate having a flat surface that is transparent to incident light and has a pitch shorter than the wavelength of the incident light. Since it is provided with an array of a large number of strip-shaped conductive elements which are arranged at intervals and are embedded so that the surface is flush with the flat surface of the substrate, the heat resistance is good and the adhesion of the conductive elements to the substrate is good. It is excellent in durability because it is good. In addition, since the surface is flat and has no irregularities, even if it is touched by hand, it can be easily removed, and handling becomes easy.
[0062]
In the manufacturing method of the present invention, a product substrate is pressed through a curable resin on the surface of a mold having a fine shape on the surface, and the inverted shape of the surface shape of the mold is transferred to the resin, and the resin is cured. After the mold is peeled off with the resin bonded to the product substrate, the shape transferred to the resin is transferred to the product substrate by dry etching to produce an article having a fine surface structure. As a result, it has become possible to mass-produce mass-produced products with high precision in a fine structure (high-precision three-dimensional surface structure). It is possible to simplify the production process to make the production process reproducible and easy, thereby realizing cost reduction.
[Brief description of the drawings]
FIGS. 1A and 1B are views showing a polarization optical element according to one embodiment, in which FIG. 1A is a schematic plan view, and FIG. 1B is a cross-sectional view of the conductive element array portion of FIG. .
FIG. 2 is a process sectional view showing a first half of an embodiment of a manufacturing method.
FIG. 3 is a process sectional view showing the latter half of the embodiment of the manufacturing method.
FIG. 4 is a schematic perspective view showing a conventional polarization optical element.
[Explanation of symbols]
2 Synthetic quartz substrate
4 Conductive element
4a Groove structure
6 Anti-reflective coating
10 Mold base material
12 Photosensitive material for electron beam
10a Mold
14 Mold shape
16 UV curable resin

Claims (13)

Transparent to the incident light, the flat surface of the inorganic dielectric substrate having a flat surface, the same width, the same depth, are arranged at equal intervals at a pitch shorter than the wavelength of the incident light, the surface is A polarizing optical element comprising an array of a number of strip-shaped conductive elements embedded so as to be flush with a flat surface of a substrate. 2. The polarization optical element according to claim 1, wherein an anti-reflection film is formed on a surface of the substrate on which the band-shaped conductive element array is embedded and a surface opposite to the surface. The polarizing optical element according to claim 1, wherein a conductive layer connected to the band-shaped conductive element is embedded in a region other than a region where the band-shaped conductive element array is formed. A manufacturing method for manufacturing a polarizing optical element including the following steps (A) to (F) in that order.
(A) A step of manufacturing a mold having a fine shape composed of a number of convex arrays having the same width and the same height on a flat surface and arranged at equal intervals at a pitch shorter than the wavelength of the incident light. .
(B) a step of pressing a product substrate against the surface of the mold via a curable resin and transferring the surface shape of the mold to the resin on the product substrate;
(C) a step of curing the resin.
(D) a step of peeling the resin from the mold while the resin is bonded to the product substrate.
(E) a step of transferring the shape transferred to the resin to the product substrate by a dry etching method.
(F) a step of filling a recess formed in the surface of the product substrate with a metal in the step (E). The manufacturing method according to claim 4, wherein the mold surface is subjected to a release treatment before the product substrate is pressed against the mold surface via the resin in the step (B). The method according to claim 4, wherein the resin is an ultraviolet curable resin. The manufacturing method according to any one of claims 4 to 6, wherein the fine shape of the mold surface is formed by providing the following steps (G) to (I) in that order.
(G) a step of applying a photosensitive material on the surface of the mold base material on which the fine shape is to be formed.
(H) a step of drawing a desired shape on the photosensitive material with an electron beam, and then developing the photosensitive material to form a desired shape on the photosensitive material.
(I) a step of transferring the shape of the photosensitive material to the mold base material by a dry etching method. 8. The method according to claim 7, wherein the mold base material is a material that can be dry-etched, and is one selected from the group consisting of a silicon material, a semiconductor material, a metal material, a glass material, a ceramic material, a plastic material, and a hard rubber material. The manufacturing method as described. The method according to claim 4, wherein in the step (F), a film is formed by an AL-CVD method using AL as a metal material for filling the concave portion. The manufacturing method according to claim 9, wherein the AL-CVD method includes the following steps (J) and (K).
(J) a step of forming a seed layer made of Ti or TiN material on the surface of the product substrate in which the concave portion is formed.
(K) forming an AL-CVD film on the seed layer until the recess is completely filled. 5. The method according to claim 4, wherein the steps (E) and (F) are performed in the order of the following steps (L) to (N).
(L) The dry etching step of the step (E) is interrupted at a stage during which the resin layer remains on the surface of the product substrate, and in that state, the surface of the product substrate on which the recess is formed is made of Ti or TiN material. Forming a seed layer;
(M) A lift-off step of removing the resin layer remaining on the substrate surface together with the seed layer thereon.
(N) a step of selectively forming an AL-CVD film on the substrate surface until the concave portion in which the seed layer remains is completely filled with the concave portion. The method according to claim 4, wherein the step (F) includes the following steps (O) and (P).
(O) After the metal is formed to a thickness greater than the depth of the concave portion, the metal layer is heated to a temperature higher than the temperature at which the metal melts in a vacuum chamber without exposing the metal layer to the air, and the surface of the metal layer is heated to reflow. Process.
(P) Thereafter, the step of removing the flattened metal layer until the surface of the product substrate is exposed. 13. The method according to claim 12, wherein the step (P) is performed by a CMP method or an etch-back method.

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