KR101042257B1 - Hybrid micro lens array and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a hybrid micro lens array having a reflection / fingerprint function and an infrared filter function in addition to a lens function having a focal length, and a method of manufacturing the hybrid micro lens array, comprising: a glass or polymer substrate having an infrared filter function; And a plurality of lens parts formed on the substrate to have a predetermined focal length and having a nano-surface structure having reflection and anti-fingerprint functions on the surface thereof.

Micro Lens Array, Anti-reflective, Anti-fingerprint, Infrared Filter, Nano Surface Structure

Description

Hybrid micro lens array and manufacturing method thereof

The present invention relates to a hybrid micro lens array having a reflection / fingerprint function and an infrared filter function in addition to a lens function having a focal length, and a manufacturing method thereof.

In recent years, the demand for high-end models integrated with digital cameras, MP3 players, etc., is a key product in the IT industry, and the demand for high-definition and slimmer camera phones is particularly high. That is, as the number of pixels of the sensor mounted on the camera module increases, a technique for slimming while having an auto focusing function (AF) is required.

As a main component provided in the camera module, there is a micro lens.

The microlenses have been applied to various components in the field of optical communication, medical devices, multimedia devices, electronic devices as well as camera modules. For example, the microlenses are used to prevent the spread of the laser in the connection portion between the semiconductor laser and the optical fiber, or to improve the performance of the display by increasing the efficiency of the sensor in the light sensing sensor.

The microlenses are manufactured in various ways. For example, an etching method using a laser pulse, a reflow method using a PR (Photo Resister), a dry etching method, a glass surface processing method using a CO ₂ gas laser, a method using a surface tension of the molten glass, Laser deposition of polymers, ion beam processing, inkjet technology, PR heating, grace kale masking and embossing molding.

In the case of glass lens processing, the glass lens is molded at a high temperature of about 800 degrees Celsius using an expensive high temperature molding machine, so that the life of the template becomes a problem, and the glass material for molding is limited to a few, and thus the optical system There are drawbacks to design constraints.

Polymer microlenses manufactured using injection molding technology, which is currently used the most, have advantages such as light weight, high degree of freedom of processing, ease of mass production, and excellent impact resistance, whereas low heat resistance, There are also disadvantages such as high coefficient of thermal expansion, weak surface damage and low variety of polymer types.

In addition, the injection molding technology is capable of molding a micro lens in a very short time, but requires a very large and expensive equipment and a mold, there is a disadvantage that many micro lenses cannot be manufactured in one molding.

In addition, the embossing technology mainly uses a thermoplastic polymer or an ultraviolet curing epoxy, and is very advantageous to form micron micropattern structure on the polymer (plastic) very precisely, which takes a longer time than injection molding. It is possible to mold several to several tens of times more microlenses in an array form than molding, and thus, it is possible to secure price competitiveness through mass production. In addition, the embossing technology can also produce a micro-lens array of a double-sided structure, it is a very easy technology to manufacture not only a micro lens array of various structures and shapes, but also MEMS devices, via fluid devices, display devices, optical devices.

However, as mentioned earlier, as the demand for multifunctional, high-quality and high-end models has increased in recent years, anti-reflective, oil, dust, or water droplets, which do not reflect light in addition to the lens function with focal length, form a clear transmission window There is a demand for a camera module having various functions such as an anti-fingerprint function and an infrared filter function to block infrared rays.

Accordingly, there is a need for a hybrid micro lens array having various functions such as reflection / fingerprint prevention and infrared blocking, instead of only having a focus function, to enable the implementation of the required camera module.

As a means for solving the above problems, a hybrid micro lens array according to an aspect of the present invention, glass or polymer based infrared filter substrate; And a plurality of lens units formed on the substrate to have a predetermined focal length and having a nano-surface structure having reflection and anti-fingerprint functions on the surface thereof.

As another means for solving the problem, a method of manufacturing a hybrid micro lens array according to another aspect of the present invention includes forming a micro lens array in which a plurality of lens units are arranged on a glass or polymer based infrared filter substrate; And forming a nano surface structure having reflection and anti-fingerprint functions on the surface of each lens unit.

As another means for solving the problem, according to another aspect of the present invention, there is provided a method of manufacturing a hybrid microlens array, including: a first microlens array mold in which the shape of the lens portion is intaglio and a second microlens in which the shape of the lens portion is embossed Manufacturing an array mold; Placing a glass or polymer substrate between the first micro lens array mold and the second micro lens array mold, and performing a thermal or ultraviolet embossing process to form a double-sided micro lens array; Forming a nano surface structure on the double-sided micro lens array to prevent reflection and stake; And forming an infrared filter on the surface of the microlens array of the double-sided structure by room temperature plasma coating.

According to the above configuration, the present invention is equipped with not only a focus function but also a fingerprint / anti-reflective function and an infrared filter function, and can be applied to a high quality camera phone, an ultra-slim camera module, a display panel, a solar cell light condensing module, and the like. A multifunctional micro lens array may be provided, and in addition, the multifunctional micro lens array may be manufactured in a short time and may be mass produced in a simple manner.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, in describing in detail the operating principle of the preferred embodiment of the present invention, if it is determined that the detailed description of the related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

In addition, the same reference numerals are used for parts having similar functions and functions throughout the drawings.

1 is a view showing a hybrid micro lens array according to an embodiment of the present invention, (a) is a cross-sectional view, (b) is a top view, and (c) is a surface cross-sectional view of each lens.

Referring to FIG. 1, a hybrid micro lens array according to the present invention is formed to have a curved surface by a polymer or glass-based infrared filter substrate 11 and a glass or a polymer material on the substrate 11, and reflect And a plurality of lens portions 12 having nano surface structures 13 for fingerprint prevention.

The micro lens array may be manufactured by a thermal reflow process, or may be manufactured by a replication process.

The diameters and heights of the plurality of lens parts 12 are determined according to the focal lengths given to the lens parts 12 in a range of 0.1 μm to 99 mm. Assuming that the lens portion 12 is a perfect spherical surface, the relationship between the radius of curvature R, the refractive index n and the focal length f of the surface of the lens portion 12 is the lens maker's formula f = R / (n- 1), the relationship between the radius of curvature R, the diameter D of the lens portion 12, and the height h is given by h = R- (R ^2- (D / 2) ² ) ^1/2 . Therefore, the diameter D and height h of the lens part 12 are adjusted according to thermal reflow process conditions, and a desired focal length f can be obtained.

In addition, the glass or polymer-based infrared filter substrate 11, which reflects infrared light and transmits visible light, the maximum transmission (Tmax) of infrared light is 3% or less at a wavelength of 700 ~ 1000nm, 1000 ~ 1100nm The wavelength is preferably 5% or less, and in the case of visible light, it is desirable to have a minimum transmission (Tmin) of 85% or more and an average transmission (Average Transmission, Tavg) of 90% or more at a wavelength of 420 to 620 nm.

The nanosurface structure 13 formed on the lens surface may be formed by plasma treatment, dry / wet etching or electron beam lithography. In addition, for effective reflection / fingerprint prevention, the height of the nano-surface structure should be at least 40% of the longest wavelength of visible light in the visible wavelength range, and the spacing of the nano-surface structure should be shortest when the light is perpendicularly incident. The wavelength should be less than the refractive index of the material, and when light enters the oblique angle, it should be less than half the value of the shortest wavelength divided by the refractive index of the material. Figure 1 (c) shows an example of the nano-surface structure of the hybrid micro lens array according to the present invention.

In the above, when the height of the nanosurface structure 13 is 40% or more of the longest wavelength of visible light, the effective refractive index of visible light may gradually change from the outermost surface of the nanosurface structure 13 to the lens part 12. It is because the reflectance with respect to visible light in a surface becomes small, so that it is so high. For example, if the height of the nanosurface structure 13 is greater than 50% of the longest wavelength of visible light, then the reflectance will be less than 0.005 for all visible light.

In addition, the reason that the period of the nano-surface structure 13 should be less than 1/2 of the shortest wavelength divided by the refractive index of the material or the shortest wavelength divided by the refractive index of the material is the nano-surface structure 13. In order to prevent the transmitted light in the higher-order mode such as first-order or second-order when considering a diffraction grating. Since the nano-surface structure 13 uses the principle of reducing the reflectivity by gradually changing the effective refractive index without diffracting the incident visible light, the period should be adjusted so that only the 0 th order transmitted light and the 0 th order reflected light are generated.

By the above-described structure, the hybrid microlens array of the present invention reflects infrared rays through the substrate 11 and filters them, and at the same time, the visible light region is formed through the nanosurface structure 13 formed on the surface of the lens unit 12. This can prevent reflections and oil or water droplets from forming on the surface.

The above-described hybrid micro lens array is formed in one substrate, and can be produced in large quantities through a replication process.

Hereinafter, a method of manufacturing the hybrid micro lens array will be described.

In one embodiment of the present invention, the hybrid micro lens array, after forming a micro lens array in which the plurality of lens units are arranged on a glass or polymer based infrared filter substrate, the nano-surface structure on the surface of each lens unit It is made in the order of forming.

2 to 6 are process charts showing an example of a process of forming the micro lens array.

First, FIG. 2 is a process diagram illustrating a process of forming a micro lens array by a thermal reflow process.

Referring to FIG. 2, first, as shown in (a), spin coating a polymer resin 22 for reflow on a glass or polymer substrate 21 is applied to a desired thickness, and the polymer resin 22 is applied. After baking, the polymer resin 22 is optionally developed after UV irradiation using the mask 23 on which a desired pattern (ie, a lens array pattern) is formed. By this, as shown in (b), the polymer resin 22 of the portion exposed to UV is removed, and only the polymer resin pattern 22a of the portion protected by the mask 23 remains.

In this state, the substrate 21 on which the polymer resin pattern 22a is formed is heated in a hot plate or oven at a temperature of about 180 ° to 200 ° for 30 seconds to 10 minutes. By the heating process, the polymer resin pattern 22a is fluidized and reflowed to complete the microlens array 20.

In this case, the period and height of each formed microlens may be changed by adjusting the reflow temperature and time, thereby manufacturing a gapless microlens array without gaps between the lenses. The micro lens array may be manufactured in a square array structure and a hexagonal array structure.

In an embodiment of the present invention, the hybrid microlens array according to the present invention may be manufactured directly through the thermal reflow process of FIG. 2. In this case, the substrate 21 is implemented as a glass or polymer based infrared filter substrate. The glass or polymer based infrared filter substrate may be implemented by forming an infrared filter on one side of the substrate by plasma coating the glass or polymer substrate at room temperature (80 degrees or less). In another case, after performing the process of FIG. 2 using the substrate 21 as a glass or polymer substrate, the infrared filter is formed under the substrate of the micro lens array 20 to form the hybrid micro lens array of the present invention. It can also be implemented.

In another embodiment of the present invention, after manufacturing a mold to be used in the replication process using the microlens array produced by the above-described thermal reflow process, the microlens array can be mass-produced by the replication process using the mold. .

FIG. 3 is a flowchart illustrating a process of fabricating a microlens array mold for a replication process, and more specifically, a microlens array mold of a polydimethylsiloxane (PDMS) material according to another embodiment of the present invention.

The mold forming process using the PDMS is a method well known in the art, and will be described briefly below.

As shown in FIG. 3A, when the microlens array 20 is manufactured by the process of FIG. 2, as shown in FIG. 3B, silicon is contained on the microlens array 20. PDMS, a polymer, is poured to a certain thickness to cure. Then, when the micro lens array 20 is removed, the micro lens array mold 30 of PDMS material is completed.

The above method for molding a PDMS mold is used to directly manufacture a micro bio / fluidic device, and accordingly, it is possible to mold a micro lens array pattern very simply.

4 is a process chart showing a process of manufacturing a hybrid micro lens array according to the present invention using the PDMS micro lens array mold manufactured in FIG. 3.

Referring to FIG. 4, in order to fabricate a hybrid microlens array by a replication process, as shown in (a), heat and ultraviolet molding may be performed on a glass or polymer based infrared filter substrate 41. Thermoplastic or thermosetting or UV curable polymer resin 42 is applied.

The substrate 41 may be implemented by forming an infrared filter on one surface of the substrate by plasma coating the glass or polymer substrate at room temperature (80 degrees or less).

The polymer resin 42 is applied to the other side of the substrate 41 is not coated with an infrared filter.

As shown in FIG. 4B, the PDMS micro lens manufactured by the process of FIG. 3 while applying heat or ultraviolet (UV) to the top and bottom of the substrate 41 to which the polymer resin 42 is applied. The coated polymer resin 42 is embossed with an array mold 43.

The above-described process procedure can be modified. For example, in Figure 4 (a) is coated with a polymer resin for embossing on a general glass or polymer substrate having no infrared filter function, and the applied polymer resin is embossed molding using a PDMS micro lens array mold 43 After that, plasma coating may be performed to form an infrared filter on a surface of the substrate where the polymer resin is not embossed.

FIG. 5 is a flowchart illustrating a process of fabricating a microlens array mold, more specifically, a nickel microlens array mold for a replication process according to another embodiment of the present invention.

Referring to FIG. 5, in the microlens array mold according to an embodiment of the present invention, as shown in (a), when the microlens array 20 is manufactured by the thermal reflow process shown in FIG. 2, As shown in (b), nickel electroplating 51 is performed on the microlens array 20 to a predetermined thickness. Then, by removing the micro lens array 20, the micro lens array mold 50 made of nickel material is completed.

FIG. 6 is a process diagram illustrating a process of fabricating a hybrid microlens array according to the present invention using the nickel microlens array mold manufactured through the process illustrated in FIG. 5.

6, in order to fabricate a hybrid micro lens array according to an embodiment of the present invention, as shown in (a), for thermal and ultraviolet embossing molding on the glass and polymer based infrared filter substrate 61 The polymer resin is applied.

Here, the substrate 61 uses a substrate in which an infrared filter is formed on one surface by room temperature plasma coating, similarly to the description of FIG. 4. The polymer resin for embossing is a thermoplastic or thermosetting polymer resin or a UV curable polymer resin as before.

And as shown in Figure 6 (b), while pressing the nickel micro lens array mold 50 produced by the process of Figure 5 on the upper surface of the substrate 61 is coated with the embossing polymer resin 62 The upper surface of the substrate 61 is embossed by irradiation with heat and ultraviolet rays.

The procedure of the above-described process may be changed in some cases. For example, a general glass or polymer substrate may be used as the substrate 61 without using a glass or polymer based infrared filter substrate, and in this case, the other side of the substrate on which the lens portion is not formed after embossing is completed. The coating is carried out to have an infrared filter function.

7 is a flowchart illustrating a process of forming a nano-surface structure having a reflection / fingerprint function according to an embodiment of the present invention.

Referring to FIG. 7, according to an embodiment of the present disclosure, a reflection / fingerprint preventing structure 73 is formed on the surface of the lens unit 72 of the micro lens array 71 in which an infrared filter based on glass and a polymer substrate is manufactured. Form.

The micro lens array 72 is manufactured by the thermal reflow process shown in FIG. 2 or the embossing process in FIG. 4 or FIG.

The antireflective structure 73 formed on the microlens array is a nanostructure form produced by plasma treatment, dry / wet etching, or electron beam lithography. In the visible wavelength range, the height of the nanostructure is at least visible light. 40% of the longest wavelength should be. For example, if the longest wavelength of visible light is about 750 nm, the height of the nanostructures should be at least 300 nm.

In addition, when light is incident vertically, the nanostructure period should be smaller than the shortest wavelength divided by the refractive index of the material. For example, when the shortest wavelength of visible light is about 400 nm, when the polymer material of the lens unit 72 is PMMA (n = 1.49), the interval between the nanostructures should be smaller than 270 nm, and the polymer material may be In the case of COC (n = 1.53), the nanostructure spacing should be smaller than 260 nm, and if the polymer material is PC (n = 1.586), the nanostructure spacing should be smaller than 252 nm. Therefore, the nanostructure spacing applicable to all materials is less than 250 nm.

In addition, when the light is obliquely incident, the spacing of the nanostructures should be smaller than 1/2 of the value of the shortest wavelength divided by the refractive index of the material. For example, when the shortest wavelength is about 400 nm, when the light is obliquely incident, the nanostructure spacing should be made smaller than 125 nm, which is less than 1/2 of 250 nm.

Combining the above results, in the antireflection / fingerprint structure 73, the height of the nanostructure should be 300 to 350 nm, and the size and spacing of the nanostructure should be 200 to 250 nm. However, in consideration of oblique incidence of light, the size and spacing of the nanostructures are preferably 100 to 125 nm.

The hybrid micro lens array manufactured as described above has one side having an infrared filter function, and the other side has a reflection / fingerprint function.

8 is a process diagram illustrating a process of manufacturing a micro lens array having a double-sided structure according to another embodiment of the present invention.

Using the PDMS micro lens array mold or the nickel micro lens array mold manufactured by the process of FIGS. 3 and 4, a micro lens array having a double-sided structure may be manufactured.

Referring to FIG. 8, in manufacturing a mold for manufacturing a microlens array having a double-sided structure using the process of FIG. 3 or 4, one mold 82 is manufactured so that the shape of the lens is engraved. Another mold 83 is manufactured such that the shape of the lens is embossed.

Embossing molding of a polymer or glass substrate 81 using the two molds 82 and 83 produces a double-sided micro lens array 84. In this case, when the nickel die is used as the molds 82 and 83, the microlens array is manufactured by a thermal embossing process, and when the PDMS mold is used, the microlens array is manufactured by a UV embossing process.

The double-sided embossing process simultaneously forms a polymer or glass substrate 81 placed between two molds 82 and 83 using the two molds 82 and 83. In the case of the thermal embossing process, the upper end of the substrate 81 is heated, the lower end is heated, or the upper and lower ends are simultaneously heated while the two molds 82 and 83 are pressurized and pressurized. . In the case of the UV embossing process, the two molds 82 and 83 are pressed by molding while irradiating UV from the upper end or the lower end of the substrate 81, or both the upper and lower ends.

The nanostructure is formed on the double-sided micro lens array by plasma treatment, dry / wet etching, or electron beam lithography, thereby adding a reflection / fingerprint protection function or an infrared filter function by plasma coating.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and it is common in the art that various substitutions, modifications, and changes can be made without departing from the technical spirit of the present invention. It will be apparent to those skilled in the art.

1 is a structural diagram of a hybrid micro lens array according to an embodiment of the present invention;

2 is a process chart showing a microlens array manufacturing process by a thermal reflow process in the method of manufacturing a hybrid microlens array according to an embodiment of the present invention;

3 is a process chart showing a process of manufacturing a PDMS micro lens array mold in the method of manufacturing a hybrid micro lens array according to an embodiment of the present invention;

4 is a process chart showing a microlens array manufacturing process using a PDMS microlens array mold in the method of manufacturing a hybrid microlens array according to an embodiment of the present invention;

5 is a process chart showing a process of manufacturing a nickel micro lens array mold in the method of manufacturing a hybrid micro lens array according to an embodiment of the present invention;

6 is a process chart showing a manufacturing process of a micro lens array using a nickel micro lens array mold in the method of manufacturing a hybrid micro lens array according to an embodiment of the present invention;

7 is a flowchart illustrating a process of forming a nano surface structure in a micro lens array in the method of manufacturing a hybrid micro lens array according to an embodiment of the present invention; and

8 is a view illustrating a method of manufacturing a hybrid microlens array having a double-sided structure and its structure according to another exemplary embodiment.

Claims (24)

delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete Manufacturing a first micro lens array mold having a negatively shaped lens portion, and a second micro lens array mold having a positively shaped lens portion; Placing a glass or polymer substrate between the first micro lens array mold and the second micro lens array mold, and performing a thermal or ultraviolet embossing process to form a double-sided micro lens array; At least 40% of the longest wavelength of visible light in the visible light region which is high on the surface of the lens array for reflection and fingerprint prevention on the double-sided micro lens array, and the size and spacing are the shortest wavelength when the light is vertically incident. Forming an unevenness less than a value divided by the refractive index of the material and smaller than 1/2 of the value obtained by dividing the shortest wavelength by the refractive index of the material when light enters oblique incidence; And Forming an infrared filter by the room temperature plasma coating on the surface of the micro-lens array of the double-sided structure. The method of claim 18, The height of the unevenness is 300 to 350nm, The interval between the concavities and convexities is 200 to 250nm when the light is incident vertically, and 100 to 125nm when the light is incident obliquely, the method of manufacturing a hybrid micro lens array. The method of claim 18, The first and second micro lens array molds are made of polymethylmethacrylate (PDMS) or nickel. The method of claim 18, wherein forming the unevenness A method for producing a hybrid micro lens array, characterized in that it is formed through any one of plasma treatment, dry or wet etching, and electron beam lithography. The method of claim 18, The infrared filter has a maximum transmission (Tmax) of infrared light of 3% or less at a wavelength of 700 to 1000 nm, a minimum of 5% at a wavelength of 1000 to 1100 nm, and a minimum transmittance of visible light of 85% or more at a wavelength of 420 to 620 nm. And an average transmission (Tavg) of visible light is 90% or more. The method of claim 18, The diameter and height of the lens unit is determined in accordance with the focal length in the range of 0.1㎛ ~ 99mm, the method of manufacturing a hybrid micro lens array. 19. The method of claim 18, wherein the lens unit is arranged in a square array structure or a hexagonal array structure.

Images