KR20040093607A - Manufacturing method of hybrid microlens array - Google Patents

Abstract

PURPOSE: A method for fabricating a hybrid micro-lens array is provided to form a low-priced hybrid micro-lens by improving a fabrication process. CONSTITUTION: A plurality of holes are formed on a substrate(11). A plurality of micro lens(13) are inserted into the holes. A melted glass solution(15) is injected into the micro lens. The melted glass solution is hardened. A polishing process for the substrate, the micro lens, and the glass is performed. A polymer is coated on an unpolished surface of the micro lens. The surface of the micro lens including the polymer is pressed by an aspheric mold(22). The polymer is hardened by the light. The aspheric mold is removed therefrom. The polishing process for the substrate, the micro lens, and the glass is performed.

Description

Manufacturing method of hybrid microlens array

The present invention relates to a method of manufacturing a microlens array, and more particularly, to a method of manufacturing a hybrid microlens array having a high number of apertures.

The microlens refers to a microlens having a size of several micrometers, and the microlens array refers to an optical structure in which microlenses are arranged in one or two dimensions. The microlens improves the sensitivity of a one-dimensional image sensor used in a solid-state image pickup device such as a light converging means, a light converging means for coupling with a light receiving element, a CCD or an optical pickup for recording information on or reproducing information from an optical disc. In order to condense incident light to a photoelectric conversion region, the light collecting means is used for condensing or imaging means, an imaging means for forming an image to be recognized by a printer on a photosensitive member, a filter for processing optical information, and the like.

In particular, microlenses used for optical pickup have been actively researched to develop high-numbered microlenses in a very small size according to the miniaturization of optical disk and integration of optical information density. In a conventional method of manufacturing a microlens array, microlenses are formed by grinding or diamond turning a rotationally symmetric optical surface in a mold using an injection molding method or a compression molding method. However, the injection molding method tends to reduce the precision of the lens by forming a scratch on the surface of the microlens, and has the disadvantage of poor fill factor and optical accuracy. Diamond turning can be used to make optical surfaces less than 2 millimeters in size, but the setup of the device is difficult and it is not easy to align the plurality of optical lens surfaces in the correct position.

Accordingly, the technical problem to be achieved by the present invention is to improve the above-described problems of the prior art, and to provide a microlens array manufacturing method capable of mass-producing microlenses at low cost using a simple manufacturing process using a wafer.

1A to 1H illustrate a method of manufacturing a microlens array according to an embodiment of the present invention.

<Code Description of Main Parts of Drawing>

11; Substrate 13; Microlens

15; Glass 17; Polymer

22; Aspheric mold

The present invention to achieve the above technical problem,

(a) forming a plurality of holes in the substrate, and then inserting the plurality of microlenses into the holes;

(b) injecting and curing the molten glass on top of the microlens, and then polishing the substrate, the microlens and the glass;

(c) inverting the structure formed in step (b) up and down, and then applying a polymer to the surface of the unpolished microlens and pressing the aspheric mold; And

(d) irradiating and curing the polymer with light rays, and then removing the mold and polishing the substrate, the microlens and the glass.

Preferably, the opening has a smaller central diameter than the upper opening and the lower opening.

In the above steps (b) and (d), the substrate, the microlens and the glass are flattened to the same height with a part of the surface during polishing.

In the step (d), the light rays are ultraviolet rays, and the polymer is combined on the microlenses in the form of aspherical lens.

Bonding and dicing the DOE array wafer on the microlens array wafer after step (d).

The present invention can mass-produce microlenses with high optical precision and fillability at low cost by forming objective lenses mounted on an optical pickup in the form of microlens arrays on a wafer.

Hereinafter, a method of manufacturing a microlens array according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1A to 1H are flowcharts illustrating a method of manufacturing a microlens array according to an exemplary embodiment of the present invention.

First, as shown in FIG. 1A, a plurality of holes 12 are formed by etching a silicon substrate 11 in a wafer form. The plurality of holes 12 are formed in the shape of a funnel such that the diameter of the center portion is smaller than that of the upper opening and the lower opening. Inside the plurality of holes 12 is inserted a microlens 13 of a ball lens type manufactured separately. The microlens 13 has a diameter of several to several tens of micrometers.

As shown in FIG. 1B, the molten glass 15 is injected and hardened on the upper surface of the microlens 13, and then the substrate 11, the microlens 13, and the glass 15. The surface of the wafer is mechanically polished to planarize as shown in FIG. 1C. In this process, the upper surface of the substrate 11, the microlens 13, and the glass 15 have the same height, and the lower portion of the microlens 13 over the inner center of the hole 12 is filled with the glass 15. Unformed space is formed.

The structure shown in FIG. 1C is flipped upside down and then the photopolymer 17 in the molten state is applied to the surface of the microlens 15 exposed inside the hole 12 as shown in FIG. 1D. Next, as shown in FIG. 1E, the aspherical mold mold 22 is positioned on the liquid photopolymer 17 and compressed, and then the ultraviolet light is irradiated to cure the porto polymer 17. As shown in FIG. 1F, when the mold 22 is separated, an aspherical photopolymer layer 18 is formed on the surface of the microlens 13. Mechanical polishing of the opposite side to the surface on which the aspherical photopolymer layer 18 is formed completes the hybrid microlens array 10 as shown in FIG. 1G.

On the top surface of the completed microlens array 10 is bonded a DOE (Diffractive Optical Element) array 19, which is also formed on the wafer and has a diffraction grating, as shown in FIG. 1H. The subsequent process is not shown, but the wafer combined with the microlens array 10 and the DOE array 19 is diced into an assembly of the plurality of microlenses 13 and the diffraction gratings, followed by a wiring and packaging process. Optical pickup may be prepared by performing the following steps.

The method of manufacturing a microlens array according to the present invention has the advantage that high-precision microlenses can be mass-produced at low cost by forming microlenses used for ultra-small optical pickup objective systems in an array form on a wafer.

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, the microlens array manufacturing method according to the present invention is capable of mass-producing high-precision ultra-small microlenses at low cost.

Claims (6)

(a) forming a plurality of holes in the substrate, and then inserting the plurality of microlenses into the holes; (b) injecting and curing the molten glass on top of the microlens, and then polishing the substrate, the microlens and the glass; (c) inverting the structure formed in step (b) up and down, and then applying a polymer to the surface of the unpolished microlens and pressing the aspheric mold; And (d) irradiating and curing the polymer with light, and then removing the mold and polishing the substrate, the microlens, and the glass. The method of claim 1, The opening is a microlens array manufacturing method, characterized in that the diameter of the central portion is smaller than the upper opening and the lower opening. The method of claim 1, wherein in steps (b) and (d), And the substrate, the microlens and the glass are part of the surface flattened to the same height during polishing. The method of claim 1, wherein in step (d), The light beam is a microlens array manufacturing method characterized in that the ultraviolet. The method of claim 1, wherein in step (d), The polymer is a microlens array manufacturing method characterized in that bonded to the microlens in the form of an aspherical lens. The method of claim 1, Bonding and dicing a DOE array wafer onto the microlens array wafer after step (d).