CN111221059B

CN111221059B - Method for preparing mold of micro-lens array by multiple times of same-direction etching

Info

Publication number: CN111221059B
Application number: CN202010114922.0A
Authority: CN
Inventors: 王淼
Original assignee: Jiaxing Uphoton Optoelectronics Technology Co Ltd
Current assignee: Jiaxing Uphoton Optoelectronics Technology Co Ltd
Priority date: 2020-02-25
Filing date: 2020-02-25
Publication date: 2023-01-20
Anticipated expiration: 2040-02-25
Also published as: CN111221059A

Abstract

The invention provides a method for preparing a micro-lens array mould by multiple homodromous etching, which comprises the following steps: forming an etching protection part on the substrate, wherein the etching protection part basically corresponds to the distribution of at least part of the micro lenses in the micro lens array; adjusting the etching parameters of the etching machine to obtain a proper transverse etching rate and a proper longitudinal etching rate, wherein the proper transverse etching rate and the proper longitudinal etching rate allow a curved surface which is basically consistent with the curved surface shape of at least part of the micro lenses to be etched in the substrate; and placing the substrate in an etching machine, and etching the substrate under the etching parameters so as to etch the curved surface in the substrate. The invention also provides the micro lens array prepared by the method, the micro lens array can be used as a light homogenizing sheet, and the micro lens array has micro lenses which are different in size and are randomly arranged, so that incident light cannot generate a water ripple pattern after being diffracted, and a good light homogenizing effect is achieved.

Description

Method for preparing mold of micro-lens array by multiple homodromous etching

Technical Field

The invention relates to the technical field of micro-machining of diffractive optical elements, in particular to a method for preparing a mold of a micro-lens array by multiple isotropic etching.

Background

The micro lens array is an array composed of lenses with micron-sized clear aperture and relief depth, not only has the basic functions of focusing, imaging and the like of the traditional lens, but also has the characteristics of small unit size, light weight and high integration level, so that the micro lens array can complete the functions which cannot be completed by the traditional optical element, and can form a plurality of novel optical systems.

Microlens arrays can be classified into refractive microlens arrays and diffractive microlens arrays. The diffraction type microlens array modulates and transforms light waves by utilizing a three-dimensional relief structure with the surface wavelength magnitude, and has the characteristics of lightness, thinness, flexible design and the like. As a diffractive optical element, the optical element has multiple functions such as wavefront sensing, light energy gathering, light shaping and the like, and is widely applied to many fields such as infrared photoelectric detection, image recognition and processing, optical communication, laser medicine, space optics and the like.

When the array-type microlens array is used as a light-homogenizing sheet, when the coherence of input laser is high, a water ripple pattern appears to influence the homogenization effect, and a gray level mask technology is required to be adopted for preparing the randomly-arranged microlens array.

The gray scale mask technology utilizes a gray scale mask to realize a multi-step diffraction optical element or a relief pattern with continuous phase change through one-time photoetching, and then the pattern is transferred onto a substrate with high fidelity through etching (or thin film deposition). The key point of the gray mask technology is the manufacture of a gray level mask, and two commonly used methods are a color coding mask and a high-energy electron beam sensitive glass mask. The method has the advantages of complex process and high cost.

The statements in this background section merely represent techniques known to the public and are not, of course, representative of the prior art.

Disclosure of Invention

In view of at least one of the drawbacks of the prior art, the present invention provides a method for fabricating a mold for a microlens array by multiple isotropic etching, and a microlens array fabricated by the same.

The invention provides a method for manufacturing a mold of a micro-lens array, which comprises the following steps:

forming an etching protection part on the substrate, wherein the etching protection part basically corresponds to the distribution of at least part of the micro lenses in the micro lens array;

adjusting the etching parameters of the etching machine to obtain a proper transverse etching rate and a proper longitudinal etching rate, wherein the proper transverse etching rate and the proper longitudinal etching rate allow a curved surface which is basically consistent with the curved surface shape of at least part of the micro lenses to be etched in the substrate;

and placing the substrate in an etching machine, and etching the substrate under the etching parameters so as to etch the curved surface in the substrate.

According to an aspect of the invention, the step of adjusting the etching parameters of the etcher comprises one or more of:

increasing or decreasing the SF6 content in the etching gas of the etching machine to increase or decrease the lateral etching rate;

increasing or decreasing the power of an electrode of the etcher to increase or decrease the rate of longitudinal etching;

the reaction chamber pressure of the etcher is reduced or increased to increase or decrease the rate of lateral etching.

According to an aspect of the invention, the step of forming the etching prevention part on the substrate comprises:

coating a photoresist on the substrate;

disposing a mask on the photoresist;

irradiating the mask by ultraviolet rays to partially cure the photoresist;

and removing the uncured photoresist to form the substrate with the etching protection part.

According to an aspect of the invention, wherein the microlens array comprises a first set of microlenses and a second set of microlenses, the first set of microlenses and the second set of microlenses having different specifications, wherein the at least some microlenses correspond to the first set of microlenses,

the manufacturing method further includes:

forming a second etching protection part on the substrate with the etched curved surface, wherein the second etching protection part basically corresponds to the distribution of the second group of micro lenses;

adjusting the etching parameters of the etching machine to obtain a proper transverse etching rate and a proper longitudinal etching rate, wherein the proper transverse etching rate and the proper longitudinal etching rate allow a second curved surface which is basically consistent with the curved surface shape of the second group of micro-lenses to be etched in the substrate;

and placing the substrate in an etching machine, and etching the substrate under the etching parameters to etch the second curved surface in the substrate.

According to one aspect of the invention, the first set of curved surfaces is irregularly arranged on the substrate and the second set of curved surfaces is irregularly arranged on the substrate.

According to one aspect of the invention, wherein the area of the first set of curved surfaces is larger than the area of the second set of curved surfaces.

According to an aspect of the present invention, the etching protection part and the second etching protection part are located on the same side of the substrate, and the etching machine is a dry etching machine.

According to an aspect of the invention, wherein the microlens array further comprises a third group of microlenses, the manufacturing method further comprises: and etching a third curved surface which is basically consistent with the curved surface shape of the third group of micro lenses on the substrate by a method similar to the second group of micro lenses.

According to an aspect of the invention, the manufacturing method further comprises: and obtaining the curved surface type of the micro lens array according to the target light field of the micro lens array.

The invention also provides a mold of the micro-lens array, which is manufactured by the manufacturing method.

The invention also provides a manufacturing method of the micro-lens array, which comprises the following steps:

preparing a mold by the above-described manufacturing method;

imprinting the photoresist by using the mold;

curing the photoresist to obtain a surface conforming to the curved surface of the mold;

and demolding the mold to obtain the micro-lens array.

The invention also provides a micro-lens array manufactured by the manufacturing method.

According to another aspect of the invention, wherein the microlens array is a plenoptic sheet.

The preferred embodiment of the invention provides a method for preparing a mold of a micro-lens array by adjusting the parameters of a dry etching machine to obtain a proper transverse etching rate and a proper longitudinal etching rate and performing multiple times of alignment in the same direction. The micro-lens array prepared by the method meets the requirement that micro-lenses with different sizes are randomly arranged on a substrate, and when the micro-lens array is used as a light homogenizing sheet, a water ripple pattern formed by interference is eliminated, and the homogenizing effect is improved.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

FIG. 1 shows a water wave pattern generated by a light beam after being diffracted by an array-type microlens array;

FIG. 2 schematically illustrates a curved profile obtained at different lateral and longitudinal etch rate ratios in accordance with a preferred embodiment of the present invention;

FIGS. 3A and 3B schematically illustrate masks made according to simulation results in accordance with a preferred embodiment of the present invention;

FIG. 4 illustrates a step of forming an etch shield using a mask in accordance with a preferred embodiment of the present invention;

FIG. 5 schematically illustrates a method of fabricating a microlens array mold using multiple co-etches, according to a preferred embodiment of the invention;

FIG. 6 illustrates a step of fabricating a microlens array mold using multiple co-etches in accordance with a preferred embodiment of the present invention;

FIG. 7 schematically illustrates the preparation of a microlens mold according to a preferred embodiment of the present invention;

FIG. 8 schematically illustrates the preparation of a microlens mold according to a preferred embodiment of the present invention;

FIG. 9 schematically illustrates the preparation of a microlens mold according to a preferred embodiment of the invention;

FIG. 10 is a partial perspective view showing a microlens array mold according to a preferred embodiment of the present invention scanned by a scanning electron microscope;

FIG. 11 illustrates a light field effect diagram in accordance with a preferred embodiment of the present invention;

fig. 12 shows a step of fabricating a microlens array according to a preferred embodiment of the present invention.

Detailed Description

In the following, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like are used in the orientations and positional relationships indicated in the drawings, which are merely for convenience of description and simplicity of description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and thus, are not to be construed as limiting the present invention. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first" and "second" may explicitly or implicitly include one or more of the described features. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

In the description of the present invention, it should be noted that unless otherwise explicitly stated or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection, either mechanically, electrically, or in communication with each other; they may be directly connected or indirectly connected through intervening media, or may be connected through the use of two elements or the interaction of two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. The first feature being "under," "beneath," and "under" the second feature includes the first feature being directly above and obliquely above the second feature, or simply meaning that the first feature is at a lesser level than the second feature.

The following disclosure provides many different embodiments or examples for implementing different features of the invention. To simplify the disclosure of the present invention, specific example components and arrangements are described below. Of course, they are merely examples and are not intended to limit the present invention. Furthermore, the present invention may repeat reference numerals and/or letters in the various examples, such repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. In addition, the present invention provides examples of various specific processes and materials, but one of ordinary skill in the art may recognize applications of other processes and/or uses of other materials.

The embodiments of the present invention will be described in conjunction with the accompanying drawings, and it should be understood that the embodiments described herein are only for the purpose of illustrating and explaining the present invention, and are not intended to limit the present invention.

As shown in fig. 1, when the light uniformizing sheet of the microlens array arranged in an array manner is used, a light effect test effect generates "water ripples", which affects the light uniformizing effect. If the individual microlenses are randomly arranged on the substrate, the water ripple can be eliminated or reduced.

Designing the microlens array which is randomly arranged can be realized by means of computer simulation software, firstly obtaining the curved surface type of a single microlens, and then obtaining the random distribution pattern of the microlens array. For example, firstly, according to the light effect of the target light field, a curved surface shape of the microlenses is obtained through computer simulation, and then the microlenses are randomly distributed to obtain a randomly arranged microlens array, wherein the microlens array at least comprises one group of microlenses with the same specification, and preferably comprises two or more groups of microlenses, wherein the specifications of the different groups of microlenses are different, and the description is given by taking the case that the microlens array comprises two groups of microlenses, the first group of microlenses has a first specification (a first curved surface), and the second group of microlenses has a second specification (a second curved surface). When obtaining the random distribution pattern, a plane coordinate system is set, a first group of micro lenses with a first curved surface is filled randomly, and then a second group of micro lenses with a second curved surface is filled randomly among gaps of the first group of micro lenses with the first curved surface, so that the filling rate is maximized. The first curved surface and the second curved surface have the same surface type, that is, the two curved surfaces have the same curvature; but the area of the second curved surface is smaller than that of the first curved surface, or the heights or depths of the first curved surface and the second curved surface are different. In addition, as will be readily understood by those skilled in the art, the first set of curved surfaces and the second set of curved surfaces need not be strictly distinct, and some degree of edge overlap may also be present, thereby improving fill factor. At present, some computer simulation software is available to realize the design of random arrangement of microlens arrays, and the specific design method and details thereof are not described herein again.

Therefore, the surface shape of the micro lens is obtained according to the light effect simulation of the target light field, the micro lens is randomly distributed, and finally the water ripple can be eliminated or reduced, so that a better light homogenizing effect is obtained. After obtaining the face shape and the random arrangement pattern of the microlens array, one or more masks are fabricated according to the design result of the microlens array, which will be described in detail below. The mask is used for forming etching protection parts on the substrate subsequently, so that the mask is required to correspond to the microlens arrays which are randomly arranged one by one, and the area of each opaque part is basically equivalent to the cross section area of the corresponding microlens.

The morphology and characteristics of the individual microlenses include cross-sectional area, surface profile (i.e., curvature), and depth of the curved surface. In the dry etching process, the area of the cross section is determined by the etching protection part, and if the surface type of the curved surface and the depth of the curved surface can be controlled in the etching process, the micro-lens array mould meeting the design requirement can be obtained.

According to one embodiment of the invention, the lateral and longitudinal etching rates of the etching can be adjusted according to the following method, so as to obtain the required curved surface type and depth:

1. the dry etching technique may use SF ₆ 、CF ₄ And O ₂ And etching is carried out. Wherein SF ₆ Has strong transverse etching capability of O ₂ Can play a role in protecting the side wall of vertical etching. Therefore, in the etching gas for etching the Si curved surface morphology, the SF can be increased ₆ Or using only SF ₆ To increase the lateral etch rate.

2. The power of the lower electrode of the dry etching machine is reduced, and the longitudinal etching rate is reduced. Conversely, the power of the electrode is increased, so that the longitudinal etching rate can be improved.

3. Reducing the pressure in the reaction chamber of the dry etching machine and increasing SF ₆ At a concentration of SF ₆ Sufficient circulation within the chamber to increase the lateral etch rate. Otherwise, the pressure in the reaction chamber is increased and the SF is reduced ₆ The concentration of (3) can reduce the rate of lateral etching.

Therefore, the transverse and longitudinal etching rates in the dry etching can be controlled by adjusting the following parameters: increasing or decreasing the SF6 content of the etching gas of the etcher to increase or decrease the lateral etching rate; increasing or decreasing the power of an electrode of the etcher to increase or decrease the rate of longitudinal etching; reducing or increasing the pressure in the reaction chamber of the etcher to increase or decrease the rate of lateral etching

As shown in fig. 2, by adjusting the ratio of the lateral etching rate to the longitudinal etching rate of the dry etching, a curved surface profile (i.e., curvature of a curved surface) meeting the design requirement can be obtained. The left part of fig. 2 schematically shows that different curved surface shapes can be obtained under different combinations of transverse and longitudinal etching rates, wherein the X direction is transverse and the Y direction is longitudinal; the right part of fig. 2 schematically shows that by adjusting the lateral and longitudinal etching rates, a target design profile can be obtained.

In a preferred embodiment of the present invention, a mold for forming a microlens array is formed by dry etching through two or more times of alignment, and the microlens array is manufactured by using the mold. Taking two times of alignment as an example, the first dry etching forms a series of randomly distributed first curved surfaces, the second dry etching forms a series of randomly distributed second curved surfaces, wherein the curvatures of the first curved surfaces and the second curved surfaces are the same, but the area of the second curved surfaces is smaller than that of the first curved surfaces (the area on the surface of the substrate), and the series of second curved surfaces are positioned in the gaps of the series of first curved surfaces, so that all the curved surfaces are filled in the substrate as much as possible.

Therefore, the two times of alignment requires two times of forming the etching protection portion, and two masks are required for forming the two times of etching protection portion, and both the masks are designed and manufactured according to the simulation result, as shown in fig. 3A and 3B, in which the first mask 30 and the second mask 40 are respectively shown. The first mask 30 shown in fig. 3A has a first set of opaque portions 301 thereon, corresponding to a first set of microlenses (first curved surfaces) with a larger area; the second mask 40 shown in fig. 3B has a second set of opaque portions 401, which have smaller areas than the first set of opaque portions 301 on the first mask 30 shown in fig. 3A, and are inserted into the gaps of the first set of opaque portions 301 on the first mask shown in fig. 3A, corresponding to the second set of microlenses (second curved surfaces) with smaller areas. Through the mask shown in fig. 3A and 3B, an etching guard may be formed on the Si substrate for forming a microlens array mold. As described in detail below.

FIG. 4 illustrates a method of forming an etch shield on a substrate using a mask, according to one embodiment of the invention. Described in detail below with reference to fig. 4.

In step S401: a photoresist is coated on a substrate, such as a Si substrate, and the photoresist may be, for example, a uv photoresist that will be cured when irradiated with uv light.

In step S402: a mask as shown in fig. 3A or 3B is disposed on the photoresist.

In step S403: the mask is irradiated with ultraviolet rays so that the photoresist is partially cured. As described above, since the portions of the first and second groups of

opaque portions

301 and 401 are opaque, and the rest is transparent, the photoresist at the positions covered by the first/second groups of

opaque portions

301 and 401 is not irradiated by uv rays and is not cured; while the remaining portion is irradiated with ultraviolet rays to be cured.

In step S404: and cleaning and removing the uncured photoresist by using a solvent, wherein the cured photoresist forms an etching protection part, so that the substrate with the etching protection part is obtained and can be used for the next etching operation.

Fig. 5 shows a method 500 for manufacturing a mold for a microlens array according to an embodiment of the present invention, in which etching protection portions are respectively formed on a substrate by sequentially using masks, etching parameters are adjusted, and multiple times of etching are performed to form a microlens array mold having curved surface shapes with the same curvature and different sizes. Fig. 6 shows an operational diagram of the respective steps, which is described in detail below with reference to fig. 5 and 6.

In step S501: an etch guard is formed on the substrate, the etch guard substantially corresponding to a distribution of at least some of the microlenses in the microlens array. An etch guard 604 is formed on a substrate 603, as shown in fig. 6, by etching to form a curved surface for the first set of lenses, for example by the method described in fig. 4 through the mask 30 described in fig. 3A.

In step S502: and adjusting the etching parameters of the etching machine to obtain a proper transverse etching rate and a proper longitudinal etching rate, wherein the proper transverse etching rate and the proper longitudinal etching rate allow a curved surface which is basically consistent with the curved surface shape of at least part of the micro lenses to be etched in the substrate. For example, for a first set of microlenses, the actual etching parameters are adjusted so that a curved surface substantially conforming to the curved surface profile of the first set of microlenses can be etched in the substrate 603. Step S502 may be performed by computer simulation or by actual operation experiments.

In step S503: and placing the substrate 603 in an etching machine, and etching the substrate under the etching parameters to etch the curved surface in the substrate. After the etching parameters of the etching machine are adjusted, the substrate 603 with the etching protection part 604 is placed in the etching machine, and the etching operation is started, so that a curved surface which is substantially consistent with the curved surface shape of the first group of micro lenses, namely a first curved surface, is etched in the substrate 603, as shown by a curved surface 606 in fig. 6. It should be noted that, although the curved surfaces 606 are shown to have different depths in fig. 6, in practice, the curved surfaces (recesses) formed by etching in step S503 have the same depth, only because the curved surfaces are randomly distributed on the substrate, and therefore, for different curved surfaces, the plane where the cross-sectional view is located in fig. 6 intersects with the curved surfaces at different positions, and thus the curved surfaces 606 are shown to have different depths in fig. 6.

In step S504: and forming a second etching protection part on the substrate with the etched curved surface, wherein the second etching protection part basically corresponds to the distribution of the second group of micro lenses. As shown in fig. 6, to perform the second etching, a second etch guard 605 is formed on the substrate with the aid of a second mask 40 as shown in fig. 3B.

In step S505: and adjusting the etching parameters of the etching machine to obtain a proper transverse etching rate and a proper longitudinal etching rate, wherein the proper transverse etching rate and the proper longitudinal etching rate allow a second curved surface which is basically consistent with the curved surface shape of the second group of micro lenses to be etched in the substrate.

In step S506: and placing the substrate in an etching machine, and etching the substrate under the etching parameters to etch the second curved surface 607 in the substrate.

The

etching protection parts

604 and 605 formed twice are positioned on the same side of the substrate 603, the etching machine is a dry etching machine, a first group of curved surfaces are irregularly arranged on the substrate, a second group of curved surfaces are irregularly arranged on the substrate, the curvatures of the two groups of curved surfaces are the same, and the area of the first group of curved surfaces is larger than that of the second group of curved surfaces.

By the above-described manufacturing method 500, the substrate 603 with the first set of curved surfaces 606 and the second set of curved surfaces 607 is finally obtained, which can be used as a mold for manufacturing a microlens array.

In addition, in the above embodiment, the description is given by taking two times of alignment as an example, and the scope of the present invention is not limited thereto, and may be applied to a case of single etching or more times of alignment.

As shown in fig. 7, according to a preferred embodiment of the present invention, a microlens array mold with a hemispherical random distribution is designed, and the curvature of the hemispherical section satisfies: x is the number of ² +y ² =10 (definition of coordinate system see fig. 2), first set of depths of surfaceFor 10um, the second group curved surface degree of depth is 5um.

The parameters of the first etching are as follows: SF ₆ :20sccm; upper electrode power: 800W; lower electrode power: 90W; the pressure of the reaction chamber: 5mTorr; the process time is as follows: 10s;

the parameters of the second etching are as follows: SF ₆ :20sccm; upper electrode power: 800W; lower electrode power: 90W; the pressure of the reaction chamber: 5mTorr; the process time is as follows: and 6s.

As shown in fig. 8, according to another preferred embodiment of the present invention, a microlens array mold with randomly distributed hemi-ellipsoidal shapes is designed, and the curvature of the hemi-ellipsoidal shapes in cross section satisfies: y is ² ＝3.9898-0.1598x ² The first group of curved surface depth is 2um, and the second group of curved surface depth is 1um.

The parameters of the first etching are as follows: SF ₆ :40sccm; upper electrode power: 800W; lower electrode power: 70W; the pressure of the reaction chamber: 3mTorr; the process time is as follows: 6s;

the parameters of the second etching are as follows: SF ₆ :40sccm; upper electrode power: 800W; lower electrode power: 70W; reaction chamber pressure: 3mTorr; the process time is as follows: 3s in the sequence.

As shown in fig. 9, according to another preferred embodiment of the present invention, a microlens array mold of a semi-ellipsoidal type with random distribution is designed, and the curvature of the semi-ellipsoidal type section satisfies: y is ² ＝80.983-9.001x ² The first group of curved surface depth is 9um, and the second group of curved surface depth is 6um.

The parameters of the first etching are as follows: SF ₆ :15sccm; upper electrode power: 800W; lower electrode power: 110W; the pressure of the reaction chamber: 7mTorr; the process time is as follows: 13s;

the parameters of the second etching are as follows: SF ₆ :15sccm; upper electrode power: 800W; lower electrode power: 110W; the pressure of the reaction chamber: 7mTorr; the process time is as follows: and 8s.

Fig. 10 is a partial perspective view of a microlens array mold in the embodiment of fig. 9 scanned by a scanning electron microscope, and fig. 11 is a view showing the effect of a light field of a microlens array imprinted by the microlens array mold in the embodiment of fig. 9.

The preferred embodiment of the present invention provides a method for preparing a randomly arranged microlens array mold by using a dry etching technique of two times of isotropic etching, and those skilled in the art can easily understand that an etching method for preparing a third group of curved surfaces with the same curvature and different areas as those of the first and second groups of curved surfaces by more than two times of isotropic etching also falls within the protection scope of the present invention. For example, the microlens array further includes a third group of microlenses, and the manufacturing method further includes: and etching a third curved surface which is basically consistent with the curved surface shape of the third group of micro lenses on the substrate by a method similar to the second group of micro lenses.

The invention also relates to a manufacturing method of the micro-lens array, as shown in fig. 12, the steps of manufacturing the micro-lens array by using the manufacturing method provided by the invention comprise:

in step S1201: a mold, such as substrate 603 shown in fig. 6, having a first set of curved surfaces 606 (and optionally a second set of curved surfaces 607) formed thereon is prepared using the fabrication method 500 described above.

In step S1202: and imprinting the photoresist by using the mold. For example, a photoresist (preferably an ultraviolet resist) is filled onto the mold to fill the first set of curved surfaces 606 (and optionally the second set of curved surfaces 607) on the mold.

In step S1203: and curing the photoresist to obtain a surface consistent with the curved surface of the mold. In the case of using the ultraviolet glue, the ultraviolet glue may be cured by irradiating the ultraviolet light.

In step S1204: and demolding the mold to obtain the micro lens array, wherein the curved surface shape of the micro lens in the micro lens array is consistent with the curved surface shape on the mold, so that a preset light field pattern can be projected.

The preferred embodiment of the invention provides a method for preparing a micro-lens array mould by multiple same-direction etching and a micro-lens array prepared by the method. The method utilizes the adjustment of the transverse etching rate and the longitudinal etching rate of the etching machine to obtain the curved surface shapes which accord with the design, so that the curved surfaces with different sizes are randomly distributed on the substrate. When the micro-lens array prepared by the method is used as a light-homogenizing sheet, the phenomenon of water ripples generated after diffraction is eliminated, and the light-homogenizing effect is improved.

In addition, in the above description of the present invention, the first and second sets of curved surfaces are irregularly arranged on the substrate. The present invention is not limited thereto, and the first set of curved surfaces and/or the second set of curved surfaces may be arranged regularly on the substrate, which are within the scope of the present invention.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments described above, or equivalents may be substituted for elements thereof. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method of manufacturing a mold for a microlens array, wherein the microlens array is a light homogenizer, the microlens array comprising a first set of microlenses and a second set of microlenses, the first set of microlenses and the second set of microlenses having different specifications, the method comprising:

forming a first etching protection part on a substrate, wherein the first etching protection part is basically distributed corresponding to a first group of micro lenses in the micro lens array;

adjusting etching parameters of an etching machine to obtain a proper transverse etching rate and a proper longitudinal etching rate, wherein the proper transverse etching rate and the proper longitudinal etching rate allow a first curved surface which is basically consistent with the curved surface shape of the first group of micro lenses to be etched in the substrate;

placing a substrate in an etching machine, and etching the substrate under the etching parameters to etch the first curved surface in the substrate;

forming a second etching protection part on the substrate etched with the first curved surface, wherein the second etching protection part basically corresponds to the distribution of the second group of micro lenses;

adjusting the etching parameters of the etching machine to obtain a proper transverse etching rate and a proper longitudinal etching rate, wherein the proper transverse etching rate and the proper longitudinal etching rate allow a second curved surface which is basically consistent with the curved surface shape of the second group of micro lenses to be etched in the substrate;

the first curved surface and the second curved surface have the same curvature and have different heights or depths,

the edges of the first curved surface and the second curved surface are overlapped;

placing the substrate in an etching machine, and etching the substrate under the etching parameters to etch the second curved surface in the substrate;

wherein the first curved surfaces are irregularly arranged on the substrate and the second curved surfaces are irregularly arranged on the substrate.

2. The method of manufacturing of claim 1, wherein the step of adjusting etching parameters of the etcher comprises one or more of:

increasing or decreasing SF in the etching gas of the etcher ₆ To increase or decrease the lateral etch rate;

3. The manufacturing method according to claim 1 or 2, wherein the step of forming an etching guard on a substrate comprises:

coating photoresist on the substrate;

disposing a mask on the photoresist;

irradiating the mask by ultraviolet rays to partially cure the photoresist;

4. The manufacturing method according to claim 1 or 2, wherein the area of the first set of curved surfaces is larger than the area of the second set of curved surfaces.

5. The manufacturing method according to claim 1 or 2, wherein the first etching prevention part and the second etching prevention part are located on the same side of the substrate, and the etching machine is a dry etching machine.

6. The manufacturing method of claim 1 or 2, wherein the microlens array further comprises a third set of microlenses, the manufacturing method further comprising: and etching a third curved surface which is basically consistent with the curved surface shape of the third group of micro lenses on the substrate by the same method as the second group of micro lenses.

7. The manufacturing method according to claim 1 or 2, further comprising: and obtaining the curved surface type of the micro lens array according to the target light field of the micro lens array.

8. A mold for a microlens array, produced by the production method according to any one of claims 1 to 7.

9. A method of manufacturing a microlens array, comprising:

preparing a mold by the manufacturing method according to any one of claims 1 to 7;

imprinting the photoresist by using the mold;

curing the photoresist to obtain a surface consistent with the curved surface of the mold;

and demolding the mold to obtain the micro-lens array.

10. A microlens array manufactured by the manufacturing method as set forth in claim 9.