KR100697614B1 - Diffraction grating and method of fabrication thereof - Google Patents

Abstract

A diffraction grating and a manufacturing method thereof are provided to mass-produce diffraction gratings with good optical characteristic and reliability by bonding glass substrates after antireflection-coating the glass substrates. A diffraction grating manufacturing method is composed of steps of: previously antireflection-coating a light emitting surface, that is one surface of a first glass substrate(11), emitting the diffracted light and an incident surface, that is one surface of a second glass substrate(17), receiving the incident light; coating the other surface of the first glass substrate with a film layer(12) made from isotropic organic matters or polymers; forming an uneven part(20) by pressing the film layer by a stamper having a grating pattern; irradiating ultraviolet rays on the film layer having the uneven part; bonding the first and second glass substrates by interposing an adhesive layer(16) made from isotropic organic matters or polymers with a refractive index different from that of the film layer, between the other surface of the second glass substrate and the uneven part; and curing the adhesive layer by irradiating ultraviolet rays on the adhesive layer.

Description

Diffraction grating and method of fabrication

1 is a cross-sectional view of a diffraction grating subjected to antireflective coating on a grating pattern made of a polymer or organic material.

Fig. 2 is a sectional view of a first embodiment of a diffraction grating treated with antireflection coating in accordance with the present invention.

Figure 3 is a cross sectional view of a second embodiment of an antireflective coating treated diffraction grating in accordance with the present invention.

4 is a manufacturing process diagram of a diffraction grating treated with an antireflective coating according to the present invention.

 5 is another manufacturing process diagram of the diffraction grating treated with the anti-reflective coating according to the present invention.

`` Explanation of symbols for main parts of drawings ''

11, 17: glass substrate 12: thin film layer

13, 14, 15: antireflective coating layer 16, 18: adhesive layer

20: uneven portion 30: phase delay plate

The present invention relates to a diffraction grating and a method of manufacturing the same, and more particularly, to a diffraction grating manufacturing method using an anti-reflective coating or an anti-reflective coating for forming a grating pattern on a glass substrate or plastic.

Generally, a CD player or a DVD player that reads data stored on an optical disc such as a CD or a DVD includes an optical pickup apparatus having a diffraction element or a phase element for detecting data by optical signal detection in order to read information from an optical recording medium. It is used.

The optical pickup apparatus includes a laser diode for scanning a laser beam, a diffraction grating for distributing the amount of light of the laser beam scanned from the laser diode at a predetermined ratio, and a beam reflected through the information recorded on the optical disc and the diffraction grating. And a beam splitter for transmitting or reflecting the beam at a predetermined ratio, and a photo detector for receiving the beam and detecting data.

The diffraction grating conventionally employed in the optical pickup device has a structure in which a grating pattern of irregularities having a predetermined interval is formed on a glass substrate.

The diffraction grating serves to direct one laser beam scanned from a laser diode into an optical disk by making a main beam and two sub beams.

Conventional diffraction gratings were fabricated by photolithography in an etching solution or etching gas after forming a bulk glass or quartz material on a glass substrate by sputtering or spin coating using an oxide thin film or spin on glass (SOG) method.

However, the lattice pattern produced according to the above-described manufacturing method was difficult to achieve uniformity, and the performance of the diffraction grating was unstable, making it difficult to mass-produce.

Thus, as disclosed in Korean Patent Laid-Open Publication No. 2005-17079, a UV-curable polymer is coated with a thin film layer on a glass substrate with a pattern layer of a diffraction grating, and a stamper having a molding pattern corresponding to a lattice pattern is pressed on the thin film layer. Thereafter, a manufacturing method of forming the thin film layer by irradiating ultraviolet rays and curing them is proposed.

Here, in order to increase the transmittance of light incident as a light beam, a concave-convex shape is produced by UV or embossing using a polymer or organic material on a glass substrate, and then TiO ₂ , on the glass substrate and the polymer. SiO ₂ is used to perform anti-reflection coating (AR).

1 is a cross-sectional view of a diffraction grating subjected to antireflective coating on a grating pattern made of a polymer or organic material.

In FIG. 1, a thin film layer 12, which is a lattice pattern layer made of an organic material or a polymer roll, is formed on a glass substrate 11, which is a smooth transparent material, and an antireflective coating layer 14 is further formed on the uneven portion of the thin film layer 12. The anti-reflective coating layer 14 is also formed on the surface of the glass substrate 11 in the direction incident from the laser diode side.

The manufacturing process of the anti-reflective coating is made in a large chamber in a vacuum (10 ^-5 Torr or less) and then at a high temperature (100 ~ 300 degrees) TiO ₂ , It is produced by alternately depositing SiO ₂ and the like.

At this time, since the temperature is applied in a vacuum phase, the polymer or the organic material constituting the thin film layer 12 forming the lattice pattern is expanded due to lack of thermal stability.

In addition, the degree of expansion depends on the degree of curing of the polymer, organic material and the like.

On the other hand, when the anti-reflective coating at a low temperature (40 ~ 100 degrees) in a vacuum state, there is a disadvantage that the coating layer deposited on the uneven portion lacks thermal stability and has no reliability.

Therefore, the optical properties of the diffraction grating are changed every time the antireflective coating is applied, and when the antireflective coating is applied to the uneven portion, reliability at low temperatures and yield at high temperatures are deteriorated.

The present invention has been made to solve the above problems, and the optical properties and reliable diffraction gratings by applying an antireflection coating on the glass substrate having better thermal stability and reliability than the organic material or polymer of the thin film layer forming the lattice pattern first The present invention provides a diffraction grating and a method for producing the same, which enable a large amount of the production thereof.

Diffraction grating according to the present invention for achieving the above object, in the diffraction grating having a glass substrate and a lattice pattern formed on the glass substrate, the organic material or polymer on the first glass substrate, the anti-reflective coating is pre-treated Forming a concave-convex portion constituting the lattice pattern by coating a thin film layer formed of a lamination layer, and joining a second glass substrate, on which anti-reflective coating was previously treated, through an adhesive layer made of an organic material or a polymer having a refractive index different from that of the thin-film layer. It is characterized in that formed by curing by irradiating ultraviolet rays.

Further, in the diffraction grating according to the present invention, the antireflective coating layer is TiO ₂ , SiO ₂ is characterized by including.

In addition, in the diffraction grating according to the present invention, the organic material or polymer is polycarbonate, polyimide, polyalkylate, polyester sulfone, polyolefin, acrylate, polyetherimide, acrylic, epoxy, urethane, polyester It is characterized by being selected.

In the diffraction grating according to the present invention, a phase retardation plate is inserted between the uneven portion and the second glass substrate, and the adhesive layer is formed on both surfaces of the phase retardation plate.

In the diffraction grating according to the present invention, the phase retardation plate may be inserted into two or more pieces.

On the other hand, the method of manufacturing a diffraction grating according to the present invention comprises the step of non-reflective coating on one side of the first glass substrate and the second glass substrate, coating the thin layer of the organic material or polymer on the other side of the first glass substrate Step, forming a concave-convex portion by pressing a stamper having a lattice pattern is formed on the thin film layer, irradiating ultraviolet rays to the thin film layer formed with the concave-convex portion, between the other side of the second glass substrate and the concave-convex portion Bonding the first glass substrate to the second glass substrate through an adhesive layer formed of an organic material or a polymer having a refractive index different from that of the refractive index; and curing the adhesive layer by irradiating ultraviolet rays to the adhesive layer.

The method of manufacturing a diffraction grating according to the present invention may further include inserting the phase retardation plate between the uneven portion and the second glass substrate with the adhesive layer interposed on both sides of the phase retardation plate. It is to be done.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Fig. 2 is a sectional view of a first embodiment of an isotropic diffraction grating treated with antireflection coating in accordance with the present invention.

Referring to FIG. 2, the diffraction grating according to the present invention is previously treated with an antireflective coating layer 14 on one side, and an uneven portion 20 constituting a lattice pattern on the thin film layer 12 made of an organic material or a polymer on the other side. The first glass substrate 11 having the surface formed thereon, the second glass substrate 17 having the antireflective coating layer 15 pretreated on one side thereof, and the uneven portion 20 of the thin film layer 12 and the second glass substrate ( 17) and an adhesive layer 16 interposed therebetween.

The thin film layer 12 may coat a UV curable polymer or organic material on the glass substrate 11, and the grid pattern formed of the uneven parts 20 may be formed using a stamper having a molding pattern corresponding to the grid pattern. It is formed by pressure molding.

In addition, the antireflective coating layers 14 and 15 are formed to increase light transmittance in a diffraction grating. The glass substrates 11 and 17 are placed in a chamber in a vacuum state (10 ^-5 Torr or less), and then high temperature ( 100 to 300 ° C.), TiO ₂ , SiO ₂ It is processed while depositing alternately.

The antireflective coating layers 14 and 15 may be treated in advance before the thin film layer 13 or the adhesive layer 16 is formed on the glass substrates 11 and 17.

When the antireflective coating layers 14 and 15 are pretreated on the glass substrates 11 and 17, the glass substrate having a lattice pattern made of polymer or organic material constituting the thin film layer 13 is heated at a high temperature of about 200 degrees in a vacuum state. When the antireflection coating is performed, the degree of expansion of the polymer, etc. varies by several nm, so that before the antireflection coating, even if the diffraction grating has a uniform amount ratio, the coated TiO ₂ , after the antireflection coating, is coated. When SiO ₂ or the like is deposited at a height of about 300 to 800 nm, it is possible to prevent the light quantity ratio from being changed according to the uniformity of the deposition equipment or the deposition height distribution.

Meanwhile, the adhesive layer 16 uses an isotropic organic material or polymer having a refractive index different from that of the isotropic organic material or polymer used in the thin film layer 13.

The isotropic organic substance or polymer used as the thin film layer 13 or the adhesive layer 16 may be polycarbonate, polyimide, polyalkylate, polyester sulfone, polyolefin, acrylate, polyetherimide, acrylic, epoxy, urethane , Polyester-based or the like.

The organic material or polymer coated with the thin film layer 13 on the glass substrate 11 is excellent in light transmittance, moldability and curability, and the material cost is low.

In particular, the UV curable polymer may be coated on the glass substrate 11 by spin coating or dropping, and may also form a coating by other hot embossing.

 The adhesive layer 16 is hardened by ultraviolet irradiation after the uneven portion 20 and the second glass substrate 17 of the first glass substrate 11 are bonded, so that the diffraction grating according to the present invention is the first The glass substrate 11 and the second glass substrate 17 are bonded to each other via two layers of polymer or organic material layers.

3 is a cross-sectional view of a second embodiment of an isotropic diffraction grating treated with antireflective coating in accordance with the present invention.

Referring to FIG. 3, a first glass substrate having an antireflective coating layer 14 on one side thereof in advance and a concave-convex portion 20 forming a lattice pattern on a thin film layer 12 made of an organic material or a polymer on the other side thereof are formed. (11) and a phase retardation plate between the second glass substrate 17 on which one surface of the antireflective coating layer 15 is pretreated, and the uneven portion 20 of the thin film layer 12 and the second glass substrate 17. An insertion layer 30 is formed, and adhesive layers 16 and 18 are formed between the uneven portion 20 and the phase delay plate 20 and between the second glass substrate 17 and the phase delay plate 20. It is.

In addition, as in the first embodiment, the adhesive layers 16 and 18 of the second embodiment also have the same isotropic organic substance or polymer having the refractive index different from that of the polymer constituting the thin film layer 12. Or a polymer.

In the second embodiment, the adhesive layer 16 is bonded between the uneven parts 20, the phase retardation plate 30, and the second glass substrate 17 of the first glass substrate 11, respectively. By curing by irradiation, the diffraction grating according to the present invention is bonded between the first glass substrate 11 and the second glass substrate 17 through three layers of polymer or organic material layer and the phase delay plate 30. It is configured.

Therefore, the phase retardation plate 30, which is the phase delay diffraction grating, is also treated with the glass substrates 11 and 17 in advance without the antireflective coating on the uneven portion 20 of the thin film layer 13, and then the phase retardation plate ( By inserting 30) inside and adhering and bonding together, a stable diffraction grating can be obtained.

At this time, even if two or more phase delay plates 30 are inserted, a diffraction grating may be formed at the top or the bottom of the phase delay plate 30 to be applied to all phase delay diffraction gratings.

4 is a manufacturing process diagram of a diffraction grating treated with an antireflective coating according to the present invention.

Referring to FIG. 4, a method of manufacturing a diffraction grating treated with an antireflective coating according to a first embodiment of the present invention first applies an antireflective coating to one side of a first glass substrate 11 and a second glass substrate 17 in advance. To form antireflective coating layers 14 and 15 (S41).

Next, a thin film layer 12 made of an isotropic organic material or polymer is formed on the other side of the first glass substrate 11 on the opposite side of the antireflective coating layer 14 (S42).

In order to form the uneven parts 20 of the lattice pattern, a step of forming the uneven parts 20 by pressing the stamper having the lattice pattern formed on the thin film layer 12 is performed (S43).

Here, the stamper is manufactured by forming a master having a pattern corresponding to the lattice pattern by a photolithography method and forming a molding pattern corresponding to the lattice pattern by metal plating on the pattern surface formed on the master.

The master fabrication process may use various methods such as photolithography, spin on glass, and etching.

In the photolithographic method, first, a photoresist is spin coated using a general semiconductor process and applied onto a glass or a wafer.

The height at the time of application is similar to the height of the product, in which the height is 100nm to 400nm and is applied very thinly.

After application, the plate is baked between 70 degrees and 120 degrees in a hot plate or oven, and a photomask is placed on a wafer or a glass substrate and irradiated with UV. After irradiating UV, soak in developer and make master in desired pattern. This process is a general semiconductor process, but characterized by a fairly thin height.

Next, in order to cure the thin film layer 12 having the uneven portion, a step of irradiating ultraviolet rays to the thin film layer 12 is performed (S44).

The uneven portion 20 formed as a lattice pattern on the thin film layer 12 may be formed by hot embossing in addition to UV curing.

 Thereafter, the first glass substrate is interposed between the other side surface of the second glass substrate 17 and the uneven portion 20 through an adhesive layer 16 made of an isotropic organic material or polymer different from the refractive index of the thin film layer 12. 11 and the second glass substrate 17 are bonded (S46).

In this case, since the adhesive layer 16 is made of a liquid polymer or an organic material, the adhesive layer 16 is irradiated with ultraviolet rays and cured to complete the diffraction grating (S47).

5 is another manufacturing process diagram of the diffraction grating treated with the anti-reflective coating according to the present invention.

5, a method of manufacturing a diffraction grating treated with an anti-reflective coating according to a second embodiment of the present invention according to the present invention, the second embodiment is a phase delay diffraction grating is additionally inserted into the phase delay plate It is a structure.

Here, first, the antireflective coating is formed on one side of the first glass substrate 11 and the second glass substrate 17 in advance to form the antireflective coating layers 14 and 15 (S51).

Next, a thin layer 12 made of an organic material or a polymer is formed on the other side of the first glass substrate 11 opposite to the antireflective coating layer 14 (S52).

In order to form the uneven portions 20 of the lattice pattern, a step of forming the uneven portions 20 by pressing a stamper having a lattice pattern formed on the thin film layer 12 is performed, and the thin film layer 12 having the uneven portions is formed. Irradiating ultraviolet rays to the thin film layer 12 is performed in order to cure (S53, S54).

Subsequently, a phase delay plate 30 is inserted between the uneven portion 20 of the first glass substrate 11 and the other side surface of the second glass substrate 17. Adhesive layers 16 and 18 between upper and lower surfaces between the uneven parts 20 and the phase delay plate 20 and between the second glass substrate 17 and the phase delay plate 20 through polymers or organic materials. ) Is formed (S56).

The first glass substrate 11 and the second glass substrate 17 are bonded to each other through the liquid adhesive layers 16 and 18 made of the polymer or organic material, and the ultraviolet ray is irradiated to the liquid adhesive layers 16 and 18. By hardening the adhesive layers 17 and 18, a phase delay diffraction grating may be formed.

Here, of course, two or more sheets of the phase retardation plate 30 may be inserted and joined as necessary.

As described above, in the diffraction element formed through the adhesive layers 16 and 18 made of a polymer or an organic material having a refractive index different from that of the uneven portion 20, the polymer or organic material having different refractive indices may be formed into the thin film layer 12. Or as appropriately used as the adhesive layers 16 and 18, the optical properties can be exhibited in the same manner as in the case of having the uneven portion 20 by one thin film layer 12.

According to the present invention, in order to improve the transmittances of the diffraction grating and the phase delay diffraction grating as described above, the optical properties and the reproducibility of the reliability at the time of the antireflection coating are improved, so that the characteristics of the device can be maintained the same, Improvements can lower production costs.

Although the present invention has been described in detail only with respect to the specific embodiments described, it will be apparent to those skilled in the art that various modifications and variations are possible within the technical scope of the present invention, and such modifications and modifications belong to the appended claims. .

Claims (7)

delete delete delete delete delete Anti-reflective coating on an exit surface, which is one side of the first glass substrate from which the diffracted light is emitted, and an entrance surface, which is one side of the second glass substrate, on which incident light is incident; Coating a thin film layer made of an isotropic organic material or polymer on the other side of the first glass substrate; Pressing a stamper having a lattice pattern to the thin film layer to form an uneven portion; Irradiating ultraviolet rays to the thin film layer on which the uneven portion is formed; Bonding the first glass substrate to the second glass substrate between the other side of the second glass substrate and the uneven portion through an adhesive layer made of an isotropic organic material or polymer different from the refractive index of the thin film layer; And A method of manufacturing a diffraction grating, comprising the steps of irradiating and curing the adhesive layer with ultraviolet rays. The method of claim 6, And inserting the phase retardation plate between the concave-convex portion and the second glass substrate via the adhesive layer on both sides of the phase retardation plate.

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