KR20050012109A - Manufacturing method of micro-lens - Google Patents

Abstract

PURPOSE: A method for manufacturing micro-lens is provided to manufacture a hybrid micro-lens having a diffractive lens and a refractive lens using a micro-lens and an array thereof. CONSTITUTION: At least one first lens is compression-molded using a mold. A lens holder(53a) having a hole on which the first lens is mounted and a second lens. The second lens is formed on a bottom surface of the lens holder. The first and second lenses are combined by aligning the optical axes of the first and second lenses in the hole of the lens holder. The molding operation is performed by preparing a mold having the same surface shape as that of the first lens, and molding the first lens by pressing down a first lens forming material against the mold.

Description

Manufacturing method of micro-lens

The present invention relates to a method for manufacturing a microlens, and more particularly, to a hybrid microlens using a machining process and a photo process or a nanoimprinting process and a method of manufacturing the array thereof.

Conventional microlens array manufacturing methods include a single microlens using a machining method or a microlens array using a photo process using a photosensitive agent.

1 is a view schematically showing a conventional single microlens manufacturing method using a machining method. Referring to FIG. 1, the upper mold 11 and the lower mold 13 are processed to form the surface of the lens to form a single micro lens. A lens having a ball or gab (G) shape is inserted between the upper and lower molds 11 and 13 and compressed to high temperature and high pressure in the upper and lower molds 11 and 13 to form the lens. The lens used in the machining method mainly uses glass. When manufacturing a lens from a plastic material, it is formed by injection molding using a precision mold by machining. This machining method has the advantage that very precise face machining is possible. However, there are limitations in the processing of micro lenses and it is not easy to form the lenses in an array form. This machining method is used for optical information storage devices or some optical communication lenses that require a high numerical aperture (Numerical Aperture).

2A to 2E are diagrams illustrating a conventional method of manufacturing a micro lens array using a photo process. First, as shown in FIG. 2A, the photosensitive agent 23 is applied onto the substrate 21, and as shown in FIG. 2B, a mask M having a predetermined shape is placed on the photosensitive agent 23 and irradiated with ultraviolet rays. It exposes. Developing and etching the exposed photoresist portion patterns the photoresist 23a in the form shown in FIG. 2C. When heat is applied thereto and reflowed, the photosensitive agent 23a is shaped into a photosensitive lens 23b in the form of a round spherical lens, as shown in FIG. 2D, and the refractive index of the photosensitive lens 23b is adjusted through ion exchange.

In the conventional method of manufacturing a micro lens array using a photo process, it is difficult to implement high sag for high numerical aperture and difficult to process aspherical surface for aberration correction. In addition, it is difficult to manufacture a large-diameter lens having a diameter of 500μm or more.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and provides a microlens of a hybrid lens and a method of manufacturing the array thereof in combination with a machining method and a photo process.

1 is a view schematically showing a single lens manufacturing method using a conventional machining method,

2a to 2e is a process chart showing a method for manufacturing a micro lens array using a conventional micro fabrication,

3a to 3c is a process diagram showing a method of forming a plurality of refractive lenses according to an embodiment of the present invention,

4a to 4e is a process chart showing a lens holder manufacturing method using a microfabrication according to an embodiment of the present invention,

5a to 5c is a process chart showing a manufacturing method of a lens holder by injection molding according to an embodiment of the present invention,

6A to 6E are process charts showing a method of manufacturing a diffractive lens by a photo process and a method of combining a refractive lens and a diffractive lens according to an embodiment of the present invention.

7A to 7 are process diagrams illustrating a method of manufacturing a diffractive lens by a nano imprinting process according to an embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

31 ... upper mold 33 ... lower mold

35 ... lens 35a ... convex-flat lens

41 ... substrate 42a, 42b, 46a, 46b ... alignment mark

43. Photosensitive agent 44a ... First etching area

44b ... second etching area 44 ... hole

47 ... UV curable material 48 ... Diffractive surface

49.Polymer mold 51a, 51b, 51c ... lower mold

52a, 52b, 52c ... upper mold 53a, 53b, 53c ... lens holder

54 ... step 55 ... diffractive lens

62. Mold 63. Separation layer

64 ... Substrate 65 ... Polymer

In the present invention to achieve the above technical problem,

(a) compression molding the first lens using a mold;

(b) providing a lens holder having a hole on which the first lens is seated and a second lens formed on a rear surface of the hole; And

(c) combining the first lens with the hole of the lens holder.

In the present invention, the step (a),

Preparing a mold having a surface shape of the first lens; And

And preparing a first lens forming material in the mold and compressing the first lens to form a first lens.

In the present invention, the first lens is characterized in that one surface is formed as a spherical or aspherical surface, the other surface is formed in a plane.

In the present invention, the step (b) may include forming a first etching region by coating and patterning a photoresist on the upper surface of the substrate;

Providing the hole by applying and patterning a photoresist on the back surface of the substrate to form a second etching region penetrating the first etching region; And

And bonding the bottom plate of the hole to a rear surface of the substrate to be connected to the second etching region.

In the present invention, in the step (b), it is possible to form an alignment mark on the upper surface and the bottom plate of the substrate.

In the present invention, the step (b) is characterized in that it further comprises the step of forming the bottom plate of the hole and then polishing the bottom plate.

In the present invention, the step (b) comprises the steps of: forming the second lens by applying an ultraviolet curable material on the surface of the bottom plate, compressing with a polymer mold, and then curing by irradiating ultraviolet light; And

And bonding the first lens to the hole to align the optical axis with the second lens.

In the present invention, the step (b) comprises the steps of: forming the second lens by applying a polymer on the surface of the bottom plate and compressing it into a mold having a diffractive surface, and then irradiating and curing ultraviolet rays; And

And bonding the first lens to the hole to align the optical axis with the second lens.

In the present invention, the bottom plate is characterized in that formed of a transparent glass.

In the present invention, the ultraviolet curable material is characterized in that it has a refractive index of 1.5 or more.

In the present invention, the ultraviolet curable material is characterized in that it has a light transmittance of 95% or more.

In the present invention, step (b) is,

Providing a lens holder mold comprising an upper mold and a lower mold;

Injection molding a lens holder having a hole by injecting a thermoplastic resin between the upper mold and the lower mold; And

And forming a second lens on an opposite surface of the portion where the hole is formed.

In the present invention, step (b) is,

Providing a lens holder mold comprising a lower mold including an upper mold and a second lens surface; And

And injection molding the lens holder in which the hole is formed by injecting a thermoplastic resin between the upper mold and the lower mold.

In the present invention, the upper mold of the lens holder is characterized in that it comprises a step portion for mounting the first lens.

In the present invention, the first lens is a refractive lens, the second lens is characterized in that the diffractive lens.

Hereinafter, a method for manufacturing a micro lens according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. According to an embodiment of the present invention, a method of manufacturing a microlens and an array thereof is performed by forming a plurality of refractive lenses by a machining method, forming a plurality of diffractive lenses using a photo process, and then combining the refractive lenses and the diffractive lenses. .

3A to 3C are process drawings showing a method of manufacturing a high precision high numerical aperture micro lens using a machining method. First, a high precision metal mold is formed as shown in FIG. 3A with a diamond rotating machine. The upper mold 31 is formed in a planar shape, and the lower mold 33 has a recess 32 having a surface of the same shape so as to form the lens forming material 35 in a molten state into a spherical or aspheric surface. As shown in FIG. 3B, the lens forming material 35 is positioned in the recess 32 and the upper mold 31 is compressed toward the lower mold 33 at a high temperature so that the rear surface of the lens 35 is planar. Form. The lens formed through compression molding as shown in FIG. 3C is made of a convex-flat lens 35a whose upper surface is spherical or aspherical and the lower surface is flat. Here, the material constituting the convex-flat lens 35a is generally glass.

4A to 4E are process diagrams illustrating an embodiment of a method of manufacturing a lens holder array using a photo process to expand the microlenses manufactured by the process of FIGS. 3A to 3C into an array form.

First, as shown in FIG. 4A, the photosensitive agent 43 is applied onto the silicon substrate 41, and the mask M1 is positioned on the upper surface thereof, and then exposed. When the unexposed portions are removed by the development and etching process, the silicon substrate 41 is patterned into a predetermined shape as shown in FIG. 4B. As an etching method, ICP-RIE (Inductive Coupled Plasma-Reactive Ion Etching) is used.

Next, as illustrated in FIG. 4C, the silicon substrate 41 is turned upside down, and then the photosensitive agent 43 is applied to the rear surface, and the mask M2 is positioned above the light. 4D illustrates a process of penetrating the second etching region 44b with the first etching region 44a by performing a developing and etching process. 4E shows that the glass substrate is anodic bonded to the substrate 41 so that the bottom plate 45 of the hole 44 formed by penetrating the first and second etching regions 44a and 44b is in contact with the rear surface of the substrate 41. Is showing the steps. Here, it is preferable that a glass substrate is a translucent material. Here, a chemical mechanical polishing (CMP) process may be performed to adjust the thickness of the bottom plate 45 as necessary.

5A to 5C are views illustrating an embodiment of a method of manufacturing a lens holder by injection molding, unlike a photo process, unlike in FIGS. 4A to 4E.

Referring to FIG. 5A, firstly, metal molds 51a and 52a that are precisely manufactured are prepared. The upper and lower molds 51a and 52a are manufactured precisely to the desired dimensions, and the stepped portion 54 is formed to align the refractive lens. Then, a thermoplastic resin such as PMMA (polymethlmethacrylate) is injected between the lower mold 51a and the upper mold 52a and pressurized. When the upper and lower molds 51a and 52a are separated, the lens holder 53a on which the step 54 is formed can be manufactured.

FIG. 5B is a view showing a lens holder manufacturing method in which the diffractive surface 48 is formed in the lower mold 51b so that the lens holder itself includes the diffractive lens. The diffractive surface 48 of the lower mold 51b is formed by precise machining at the time of manufacturing the lower mold 51b. Then, a thermoplastic resin such as PMMA (polymethlmethacrylate) is injected and pressed between the lower mold 51b and the upper mold 52b. Thereby, the lens holder 53b including the step portion 54 and the diffractive lens 55 can be manufactured.

5C illustrates a lens holder manufacturing method including a diffractive surface 48 but not including a step 54, unlike FIGS. 5A and 5B. The diffractive surface 48 of the lower mold 51c is formed by precise machining at the time of manufacturing the lower mold 51c. Then, a thermoplastic resin such as polymethlmethacrylate (polymethyl methacrylate) or the like is injected and pressurized between the lower mold 51c and the upper mold 52c. Thereby, the lens holder 53c including the diffraction lens 55 can be manufactured. In the case of the lens holder 53c manufactured by the above method, the microlens 35b is precisely aligned and bonded when bonded to the microlens 35b.

6A to 6D are process diagrams illustrating an embodiment of a method of manufacturing a diffractive lens, that is, a diffractive optical element (DOE) lens array by an ultraviolet embossing process, and FIG. 6E is a diffraction lens and refraction of the type shown in FIG. 3C. It shows how to arrange the lens.

6A shows a lens holder array 40 made by the process shown in FIGS. 4A-4E. In this case, the lens holder 53a manufactured in FIG. 5A may be used. The lens holder array 40 includes a substrate 41 having a plurality of hole arrays formed thereon and a bottom plate 45 forming a hole bottom surface of the substrate 41. Here, the alignment marks 42a and 42b of the substrate 41 may be used as they are for alignment with the DOE lens, or alternatively, separate alignment marks may be formed on the bottom plate 45.

As shown in FIG. 6B, a polymer mold 49 having a molten UV curable material 47 applied to the upper surface of the lens holder array 40 by spin coating and a diffractive surface 48 of a DOE lens formed thereon is formed thereon. ). The ultraviolet curable material 49 is preferably formed of a glass material having a refractive index of 1.5 or more and an internal light transmittance of 95% or more. In addition, it is preferable that the adhesiveness is excellent, detachment from the polymer mold 49 is easy, and the change in refractive index according to the temperature change is not sensitive. In particular, the ultraviolet curable material 49 should be a material capable of curing when irradiated with ultraviolet rays in the wavelength range of 200nm to 300nm. At this time, the polymer mold 49 is disposed above the ultraviolet curable material 47 so that the diffractive surface 48 corresponds to the hole 44. The diffractive surface 48 may be formed to have a Fresnel lens shape to perform not only condensing but also chromatic aberration.

The polymer mold 49 is pressed onto the ultraviolet curable material 47 as shown in FIG. 6C to form the ultraviolet curable material 47 in the same form as the diffractive surface 48. Both the polymer mold 49 and the ultraviolet curable material 57 are preferably formed of a transparent material having a high light transmittance. Ultraviolet rays are irradiated onto the polymer mold 49 to cure the ultraviolet curable material 47. FIG. 6D illustrates a structure in which a plurality of desired DOE lenses 47a are arranged on the upper surface of the ultraviolet curable material 47 with the upper polymer mold 49 removed.

6E shows that the DOE lens 47 aligns and combines the microlenses 35b manufactured by FIGS. 3A to 3C in a structure in which the DOE lens 47 is coupled to the lens holder array 40. In this case, the lens holder may be similarly applied to the lens holders 53a, 53b, and 53c manufactured by FIGS. 5A to 5C. The micro lens 35b is inserted into the lens hole 44 of the substrate 41 and bonded using an adhesive. Here, the microlens 35b is formed using a machining method as shown in FIGS. 3A to 3B. Unlike the microlens 35a shown in FIG. 3C, the left and right sides are formed to have an inclined surface, and the hole 44 is formed. Lateral damage can be reduced when inserted in the. An adhesive may be injected into the stepped portion 44s on which the microlens 35b is seated to firmly fix the microlens 35b to the substrate 41.

6A to 6D, a DOE lens may be manufactured by a nano imprinting process in addition to a method of manufacturing a diffractive lens by an ultraviolet embossing process as shown in FIGS. 6A to 6D. Nano imprinting technology can easily form a nano pattern (nanp pattern), it is possible to mass production has the advantage of high process yield. This will be described below with reference to FIGS. 7A to 7D.

Referring to FIG. 7A, a template 62 having a diffractive lens pattern, that is, a diffractive surface 48, is provided. As shown in FIG. 7B, the mold 62 having the diffractive surface 48 is positioned corresponding to the substrate 64. The polymer 65 is coated on the substrate 64 on which the diffractive lens is to be formed. The substrate 64 may be a silicon substrate, a quartz substrate, an alumina substrate, or the like. As the polymer 65 formed on the substrate 64, a thermoplastic resin such as polymethlmethacrylate (polymethyl methacrylate) may be generally used. Here, the mold 62 is formed of a material having a high light transmittance, and the polymer is used as an ultraviolet curing material in a molten state. In addition, it is preferable to perform a pretreatment for forming the separation layer 62 on the diffraction surface 48 for easy separation between the mold 62 and the polymer 65 on the substrate 64.

Next, as shown in FIG. 7C, the mold 62 is pressed by applying pressure to the substrate 64. At this time, the diffractive surface 48 formed on the mold 62 is imprinted onto the polymer 65 as it is. Both the mold 62 and the polymer 65 are formed of a transparent material having a high light transmittance, and the ultraviolet rays are irradiated from the upper part of the mold 62 to cure the polymer 65 during the compression process.

And as shown in FIG. 7D, when the mold 62 and the board | substrate 64 are isolate | separated, the diffraction lens 66 formed on the polymer 65 can be obtained. By using the mold 62 having a large number of diffractive lens patterns, an array of diffractive lens 66 can be easily obtained. That is, the diffraction lens array can be directly transferred onto the substrate 65 by such a process.

The hybrid lens manufactured according to the present invention may function as an objective lens consisting of a refractive lens having a flat surface and an aspherical curved surface in a disk direction, and a diffraction lens of a Fresnel lens type. When the light emitted from the light source enters the objective lens, the light is first refracted on the diffractive surface and then collected by the refraction lens to form a fine light spot near the diffraction limit. Therefore, in the refractive lens, the burden of refractive power for condensing is reduced and the burden for realizing a high numerical aperture during lens manufacturing is reduced.

The present invention provides a hybrid lens composed of a refractive lens and a diffractive lens and a microlens array in the form of an array thereof using conventional machining and microfabrication methods. In addition, by distributing power to the refractive lens and the diffractive lens, the production of the refractive lens by machining becomes easy. Unlike conventional lenses, since a low refractive index material and a high refractive index material may be used at the same time, a lens having a high refractive power and a similar numerical aperture may be implemented as a lightweight compact lens.

While many details are set forth in the foregoing description, they should be construed as illustrative of preferred embodiments, rather than to limit the scope of the invention. The scope of the invention should not be defined by the described embodiments, but should be determined by the technical spirit described in the claims.

As described above, an advantage of the present invention is that a refractive lens and a diffractive lens are manufactured by manufacturing a hybrid lens capable of distributing power and correcting chromatic aberration using a combination of machining, microfabrication, ultraviolet embossing, or nanoimprinting. It is to facilitate the expansion in the form of a hybrid micro lens and array comprising.

Claims (16)

(a) compression molding one or more first lenses using a mold; (b) providing a lens holder having a hole on which the first lens is seated and a second lens formed on a rear surface of the hole; And and (c) optically aligning the first lens with the second lens in the hole of the lens holder. According to claim 1, wherein step (a), Preparing a mold having a surface shape of the first lens; And And forming a first lens forming material in the mold and compressing the first lens to form a first lens. The method of claim 2, One surface of the first lens is formed as a spherical or aspherical surface, the other surface is a micro lens manufacturing method characterized in that formed in a plane. According to claim 1, wherein step (b), Coating and patterning a photoresist on an upper surface of the substrate to form a first etching region; Providing the hole by applying and patterning a photoresist on the back surface of the substrate to form a second etching region penetrating the first etching region; And And bonding a bottom plate of the hole to a rear surface of the substrate to be connected to the second etching region. The method of claim 1, wherein in step (b), And forming an alignment mark on an upper surface of the substrate and the bottom plate. According to claim 1, wherein step (b), Forming a bottom plate of the hole and then polishing the bottom plate. The method of claim 4, wherein step (b) comprises: Forming the second lens by applying an ultraviolet curable material to the surface of the bottom plate, compressing the same with a polymer mold, and then curing by irradiating ultraviolet light; And And bonding the first lens to the hole to align the optical axis with the second lens. The method of claim 4, wherein step (b) comprises: Forming a second lens by applying a polymer to a surface of the bottom plate, compressing the mold with a mold having a diffractive surface, and then irradiating and curing ultraviolet rays; And And bonding the first lens to the hole to align the optical axis with the second lens. The method of claim 4, wherein The bottom plate is a microlens manufacturing method, characterized in that formed of a transparent glass. The method of claim 7, wherein The ultraviolet curable material has a refractive index of 1.5 or more microlens manufacturing method. The method of claim 7, wherein The UV curable material has a light transmittance of 95% or more. According to claim 1, wherein step (b), Providing a lens holder mold comprising an upper mold and a lower mold; Injection molding a lens holder having a hole by injecting a thermoplastic resin between the upper mold and the lower mold; And And forming a second lens on an opposite surface of the portion in which the hole is formed. According to claim 1, wherein step (b), Providing a lens holder mold comprising a lower mold including an upper mold and a second lens surface; And And injection molding a lens holder in which a hole is formed by injecting a thermoplastic resin between the upper mold and the lower mold. The method according to any one of claims 12 or 13, The upper mold of the lens holder, characterized in that it comprises a step for mounting the first lens. The method of claim 1, And the first lens is a refractive lens. The method of claim 1, And said second lens is a diffractive lens.