KR101839461B1 - Method for making micro lens array - Google Patents

Method for making micro lens array Download PDF

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Publication number
KR101839461B1
KR101839461B1 KR1020150158816A KR20150158816A KR101839461B1 KR 101839461 B1 KR101839461 B1 KR 101839461B1 KR 1020150158816 A KR1020150158816 A KR 1020150158816A KR 20150158816 A KR20150158816 A KR 20150158816A KR 101839461 B1 KR101839461 B1 KR 101839461B1
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KR
South Korea
Prior art keywords
thin film
photoresist layer
photoresist
microlens array
substrate
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Application number
KR1020150158816A
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Korean (ko)
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KR20160063242A (en
Inventor
원용협
김준오
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한국과학기술원
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Priority to PCT/KR2015/014456 priority Critical patent/WO2017082467A1/en
Publication of KR20160063242A publication Critical patent/KR20160063242A/en
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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B3/00—Simple or compound lenses
    • G02B3/0006—Arrays
    • G02B3/0012—Arrays characterised by the manufacturing method
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
    • B29D11/00—Producing optical elements, e.g. lenses or prisms
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
    • B29D11/00—Producing optical elements, e.g. lenses or prisms
    • B29D11/00009—Production of simple or compound lenses
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B3/00—Simple or compound lenses
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/20—Exposure; Apparatus therefor
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/027—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/027—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34
    • H01L21/0271—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34 comprising organic layers
    • H01L21/0273—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34 comprising organic layers characterised by the treatment of photoresist layers

Abstract

A microlens array manufacturing method is disclosed.
In this method, first, a photoresist is applied on a substrate to form a photoresist layer. Thereafter, a part of the photoresist layer is exposed using a mask, and a thin film is formed on the photoresist layer. Subsequently, the photoresist layer on which the thin film is formed is developed and ultrasonic vibration is applied to cause the thin film to rise, and then the front thin film is subjected to front exposure to form a microlens array.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

The present invention relates to a method of manufacturing a microlens array.

Microlens arrays are basically required components in micro optical applications such as optical communications, interconnection, direct optical imaging, lab-on-a-chip, and the like.

In order to produce a high-quality microlens array, it is common to make molds for making lenses through mechanical processing.

However, this method is disadvantageous in that the cost for processing itself is high and the cost of fabricating a new mold may be burdensome if the characteristics of the microlens array to be used are different.

As a result, a method of making a microlens array more easily is used even if the quality is slightly lowered. Typically, a photoresist reflow method is used.

In this method, a cylindrical photoresist is formed on a substrate by using a lithography method and a photoresist is liquefied by applying a high temperature to form a spherical shape on the substrate by using the surface tension of the photoresist . Thereafter, when the temperature is lowered and ultraviolet light is applied, the photoresist is cured to form a microlens array

However, the microlens array manufactured in this manner is limited to fabricate only a microlens array having a short focal length due to the nature of the surface tension.

Considering that the focal length of the lens is determined by the contact angle due to the tension of the contact surface of the photoresist with the substrate and rarely has a contact angle which is very small (~ 10 degrees or less) It can be said that this method can only be used for applications requiring short focal lengths. That is, it is not a suitable method for making an imaging lens, which is an application having a relatively long focal length.

When the photoresist is reflowed, since the area of the cylindrical photoresist for reflowing becomes wider than the original size, an accurate calculation must be performed in order to prevent bonding due to surface tension to adjacent lenses.

If there is an error in the calculation or if the temperature at which the heat is applied is not constant, the coupling between the two lenses can occur at some point, which makes it impossible to use the entire microlens array. Therefore, it is necessary to set a gap to a certain distance between the lenses, which is why the fill factor is lower than other relative methods.

Further, since the surface tension is used by using the thermal fusion phenomenon, there is a difficulty that the dust adhered to the substrate greatly affects the quality of the lens. Therefore, the photoresist reflow method always has to proceed in a place where the dust concentration is low. To solve this problem, a method of forming a mold in which a dome-shaped pattern is formed by exposing ultraviolet light to a radial pattern, And a method of forming a lens by applying an electric field from above using a conductive liquid polymer is proposed. However, a more effective method for manufacturing a microlens array is required.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of manufacturing a microlens array having a long focusing distance and a high filling rate.

According to an aspect of the present invention, there is provided a method of manufacturing a microlens array,

Applying a photoresist on the substrate to form a photoresist layer; Exposing a portion of the photoresist layer using a mask; Forming a thin film on the photoresist layer; Developing the photoresist layer on which the thin film is formed and applying ultrasonic vibration to the thin film to cause the thin film to rise; And performing a front exposure on the raised thin film.

Here, in the step of forming the photoresist layer, the thickness adjustment of the photoresist layer is performed by spin coating, and soft firing is further performed after the spin coating.

Further, the thin film is characterized by being formed by total exposure to the top of the photoresist layer.

Also, the thickness of the thin film is adjusted according to a focal distance of the microlens.

Further, in the step of forming the thin film, post-exposure baking of the thin film can be further performed.

In addition, the step of ridging the thin film may include the steps of: immersing the substrate, the photoresist layer and the thin film in a developing solution; And applying vibration to the substrate, the photoresist layer, and the thin film using an ultrasonic generator.

In addition, the step of raising the thin film may include the steps of: immersing the substrate, the photoresist layer and the thin film in an ultrasonic generator containing a developer; And applying vibration to the substrate, the photoresist layer, and the thin film using the ultrasonic generator.

In addition, after performing the front exposure, the micro lens array is formed by floating the mold of the thin film after the front exposure is performed with nickel electroplating or PDMS (Polydimethylsiloxane).

Further, the photoresist is characterized by being an ultraviolet photosensitizer polymer or SU-8.

Also, the thickness of the photoresist layer is 200 to 300 mu m, and the thickness of the thin film is 25 to 40 mu m.

According to the present invention, since a microlens array can be formed as it is as a mask pattern, a complicated calculation process can be omitted.

Further, since the focal length can be adjusted by the thickness of the thin film, a lens having a considerably long focal length can also be manufactured.

In addition, since the phenomenon of swelling from the inside is used, cleaning can be performed after completion of fabrication even if the dust density of the surface is thick during the process, and microlenses can be formed according to the shape of the opening surface (circular, square, triangle, etc.) Therefore, it can be seen to have a high effect on the fill factor.

1 is a perspective view of a microlens array according to an embodiment of the present invention.
2 is a plan view of the microlens array shown in FIG.
3 is a view showing a state in which a photoresist is applied on a substrate for manufacturing a microlens array according to an embodiment of the present invention.
Fig. 4 is a view showing a state after the photoresist layer in Fig. 3 is exposed through a mask. Fig.
5 is a diagram showing a state after a thin film is formed on the photoresist layer in Fig.
Fig. 6 is a diagram showing the state of the photoresist layer in Fig. 5 after development. Fig.
FIG. 7 is a view showing a completed microlens array after exposure to the raised thin film in FIG. 6. FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, when an element is referred to as "comprising ", it means that it can include other elements as well, without excluding other elements unless specifically stated otherwise. Also, the terms " part, "" module," and " module ", etc. in the specification mean a unit for processing at least one function or operation and may be implemented by hardware or software or a combination of hardware and software have.

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

FIG. 1 is a perspective view of a microlens array according to an embodiment of the present invention, and FIG. 2 is a plan view of a microlens array shown in FIG. 1. Referring to FIG.

1 and 2, a microlens array 10 according to an embodiment of the present invention includes a substrate 100 on a rectangular plate, a photoresist film 110 formed on the substrate 100, And a plurality of microlenses 120 formed on the resist film 110.

Here, the substrate 100 is a substrate of a transparent material, for example, a glass substrate can be used.

In addition, the shape of the substrate 100 may be formed in a form other than a quadrangle, for example, a circle or the like depending on the use.

Hereinafter, the manufacturing process of the microlens array 10 will be described.

FIG. 3 is a view showing a state where a photoresist is applied on a substrate for manufacturing a microlens array according to an embodiment of the present invention.

Referring to FIG. 3, a photoresist is applied on a glass substrate 100 to form a photoresist layer 111 (S100), in the same manner as a general semiconductor process lithography method. As the photoresist, a negative photoresist SU-8 may be used, and the negative photoresist is an ultraviolet sensitive polymer.

Such photoresist layer can be subjected to thickness control through spin coating. For example, 500 rpm for 5 seconds, ramping rate 300 rpm / s to 2000 rpm, and spin coating at 2000 rpm for 20 seconds. This condition is a condition for applying the photoresist layer 111 to a thickness of 200 mu m on the glass substrate 100. The photoresist layer according to embodiments of the present invention may have a thickness of 200 to 300 um.

After the spin coating, a soft baking process may be further performed. The soft firing process may be performed by raising the ramping temperature to 95 degrees at 3 degrees / min for 5 minutes at 65 degrees, and then heating for 1 hour at 95 degrees.

Through this process, the solvent contained in the photoresist layer 111 is vaporized and the photoresist layer can be cured.

4 is a view showing a state after the photoresist layer 111 in FIG. 3 is exposed through a mask.

Referring to FIG. 4, when patterning the photoresist layer 111, a mask 200 having an opening surface is formed to allow ultraviolet light to pass through the micro lens 120 in the shape of a desired microlens 120 Exposure is performed for 40 seconds (S110). Then, the photoresist layer 111 is composed of the photoresist 112 not exposed by the mask 200 and the exposed photoresist 113. Here, the mask 200 has the same shape as a circular cross section in which the microlens 120 as shown in FIG. 2 is in contact with the photoresist layer 111.

Up to this point, it can be said that the patterning process is the same as a general photoresist patterning process.

5 is a diagram showing a state after a thin film is formed on the photoresist layer 111 in FIG.

5, after the step S110, the mask 200 is removed and the entire area is exposed for 5 seconds so that the upper portion of the photoresist layer 111 is formed as the thin film 130 (S120).

The thin film 130 is formed in order to prevent the photoresist from melting and being lost during the subsequent developing process. The thickness of the thin film 130 is determined according to the exposure time of the entire surface of the photoresist layer 111. In addition, the thickness of the thin film 130 is an element that can control the focal length of the microlens 120. For example, the thin film 130 according to an embodiment of the present invention may have a thickness of 25 to 40 um.

After the above-described exposure process (S120), a post exposure baking process may be performed at 95 degrees for 15 minutes. This post-exposure baking is carried out to further promote crosslinking of the crosslinkable moieties within the exposed areas of the photoresist.

FIG. 6 is a diagram showing the state after development of the photoresist layer 111 in FIG.

6, after the substrate 100, the photoresist layer 111, and the thin film 130 are all immersed in the developing solution after the above-described process (S120) or the post-exposure baking process, an ultrasonic generator And gives a vibration for 5 minutes using S130. In this way, the molecules of the developer penetrate between the defects of the thin film 130 due to the vibration of the ultrasonic generator, so that the mixture of the photoresist and the developing solution is combined in the thin film 130, The thin film is in a raised state.

Meanwhile, a method in which the developer is contained in the ultrasonic wave generator and the substrate 100, the photoresist layer 111, and the thin film 130 are all contained in the developer, and then the ultrasonic wave generator is used to vibrate .

FIG. 7 is a view showing the completed microlens array after exposure to the raised thin film 130 in FIG.

Referring to FIG. 7, when the front exposure (Flood Exposure) is performed in a state where the thin film 130 is protruded through the above-described process (S130), the curing progresses according to the shape of the microlens. When the curing is completed, A microlens array 10 having a lens shape is formed (S140). That is, a photoresist film 110 is formed on the substrate 100, and a microlens 120 is formed on the photoresist film 110 to finally form the microlens array 10.

Meanwhile, although the microlens array 10 produced through the above-described step S140 may be used as a lens as it is, since the transparency of the cured photoresist is lower than that of PC (poly carbonate) or PMMA (poly methyl methacrylate) The final microlens array 10 may be formed by forming a mold with nickel electroplating or PDMS (polydimethylsiloxane), and then molding the mold with PC or PMMA.

The ultraviolet light applied to the photoresist is a light having a wavelength of 365 to 400 nm with an intensity of 5 to 8 mJ / s * cm 2 .

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

Claims (8)

Applying a photoresist on the substrate to form a photoresist layer;
Exposing a portion of the photoresist layer using a mask;
Forming a thin film on the photoresist layer;
Developing the photoresist layer on which the thin film is formed and applying ultrasonic vibration to the thin film to cause the thin film to rise; And
Performing a front exposure on the raised thin film
Lt; / RTI >
Wherein the substrate on which the thin film-formed photoresist layer is formed is dipped in a developer so that the mixture of the photoresist and the developer is aggregated in the thin film by the ultrasonic vibration so that the thin film rises,
A method of manufacturing a microlens array. The method according to claim 1,
In the step of forming the photoresist layer,
The thickness adjustment of the photoresist layer is performed by spin coating,
After soft coating is further performed after the spin coating
Wherein the microlens array is formed on the substrate. The method according to claim 1,
Wherein the thin film is formed by total exposure to the top of the photoresist layer. The method according to claim 1,
Wherein the thickness of the thin film is adjusted according to a focal distance of the microlens. The method according to claim 1,
Wherein in the forming of the thin film, post-exposure baking of the thin film can be further performed. The method according to claim 1,
After performing the front exposure,
After the above-mentioned front exposure is performed with nickel electroplating or PDMS (polydimethylsiloxane), the thin film mold is removed to form a microlens array
Wherein the microlens array is formed on the substrate. 7. The method according to any one of claims 1 to 6,
Wherein the photoresist is an ultraviolet light sensitive polymer or SU-8. 7. The method according to any one of claims 1 to 6,
The thickness of the photoresist layer is 200 to 300 um,
The thickness of the thin film is 25 to 40 mu m
Wherein the microlens array is formed on the substrate.
KR1020150158816A 2014-11-26 2015-11-12 Method for making micro lens array KR101839461B1 (en)

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KR20140166780 2014-11-26

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110187417A (en) * 2019-06-27 2019-08-30 电子科技大学 The production method of PDMS film microlens array

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KR102048746B1 (en) 2017-11-24 2019-11-26 한국기계연구원 Method for manufacturing micro lens array mold
KR102427976B1 (en) * 2020-02-28 2022-08-03 (주)펨트론 Multi-focusing micrelens and method thereof
KR102556140B1 (en) * 2021-02-22 2023-07-19 한국과학기술원 Microlens based on concurrent thermal reflow and manufacturing method therof

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JP4265984B2 (en) * 2004-02-27 2009-05-20 富士フイルム株式会社 Microlens manufacturing method and apparatus, and microlens
US7297473B2 (en) * 2005-11-08 2007-11-20 Sharp Laboratories Of America, Inc. Method of forming a microlens array having a high fill factor
KR101173155B1 (en) * 2010-11-03 2012-08-16 오에프티 주식회사 Method for fabricating microlens array
CN102540284B (en) * 2012-02-07 2013-11-20 中国科学院光电技术研究所 Preparation method of micro-lens array based on negative photoresist and mask moving exposure process
KR101528594B1 (en) * 2013-09-26 2015-06-12 한국과학기술원 Large-scale Nanolens and manufacturing method thereof

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110187417A (en) * 2019-06-27 2019-08-30 电子科技大学 The production method of PDMS film microlens array

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WO2017082467A1 (en) 2017-05-18

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