JP2003098319A - Method for manufacturing microlens, and photomask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a microlens having large height and an aspheric surface form with high accuracy. SOLUTION: A photosensitive resin 3 in an uncured state is dropped on a substrate 1 and cured into a hemispheric form so that the height of the cured photosensitive resin 3a in a hemispheric form can be increased. Further, by exposing the hemispheric cured photosensitive resin 3a on the substrate 1 through a photomask 4 having the distribution of the transmittance and then developing, the exposed face of the cured photosensitive resin 3a is dissolved and removed according to the distribution of the transmittance of the photomask 4 to obtain a microlens 6 made of the hardened photosensitive resin 3a with the surface processed into an aspheric form.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method of manufacturing a microlens and a photomask used in the method of manufacturing.

[0002]

2. Description of the Related Art Conventionally, as a method for manufacturing a microlens, a method utilizing the surface tension of a liquid is known. Japanese Unexamined Patent Publication No. 2000-280367 discloses an invention in which a resin in an uncured state is dropped from a nozzle on a surface of a substrate and a hemispherical resin is cured by surface tension to form a microlens. Further, in Japanese Unexamined Patent Publication No. 9-8266, a photoresist film which is a photosensitive resin material is formed on the entire surface of a substrate, and a photomask is used to expose and develop a photo film except a position where a microlens is to be formed. An invention is disclosed in which the resist is removed, the remaining photoresist is reflowed at a high temperature to have a hemispherical shape, and the hemispherical photoresist is cured again to form a microlens. Further, Japanese Unexamined Patent Publication No. 2000-131508 discloses an invention of a two-lens lens for an optical pickup using a microlens. The microlens is manufactured by a reflow method or a lens surface is formed into an aspherical shape. The method using a gray scale mask is taken up.

[0003]

According to the invention disclosed in Japanese Patent Laid-Open No. 9-8266, the height dimension of the microlens is determined by the thickness dimension of the applied photoresist film. With a typical photoresist of the type that is exposed to ultraviolet light, the thickness dimension is at most about 100 μm due to problems with the coating method and sensitivity, and the photoresist after reflow becomes a hemispherical microlens with the same volume. Even if the height of the microlens is 100 μm
There is a limit to the degree, and it is not possible to manufacture a microlens having a too large height. Therefore, as the diameter of the microlens increases, it becomes difficult to increase the numerical aperture. Further, in this method, the shape of the microlens is determined by the surface tension, so it is difficult to form an aspherical microlens. in this way,
Due to the fact that the height of the microlens cannot be increased and the lens surface cannot be aspherical,
There is a limit to increase the numerical aperture and decrease the aberration.

According to the invention described in Japanese Unexamined Patent Publication No. 2000-280367, it is possible to manufacture a microlens having a considerably large height by controlling the viscosity of the uncured resin, the wettability of the substrate surface, and the like. Is possible. However, since the surface shape is determined by the surface tension, it is difficult to reduce the aberration by making the surface aspherical.

By using the gray scale mask disclosed in Japanese Unexamined Patent Publication No. 2000-131508, an aspherical shape can be produced, but the resist thickness is limited as in the registry flow method. Here, a general gray scale mask can give a change in transmittance of several hundreds of gradations, but if the number of gradations of the gray scale mask is “n” and the resist film thickness is “T”, then “T / n <
The precision of the lens must be ". The gray scale of the gray scale mask is the commercially available MEMSOPTI.
There are 200 manufactured by CAL. On the other hand, the accuracy of the lens used in the optical disc is about 1/10 of the wavelength used, and it is 0.05 in the DVD (wavelength λ = 0.65 μm).
An accuracy of about μm is required. T = 100 μm, n = 2
When the gradation is 00, 100/200 = 0.5 μm. In other words, if the reflow method is used as the method of manufacturing the microlens and the grayscale mask is used as the method of making the surface of the lens aspherical, it is possible to accurately form the microlens whose surface is aspherical. Can not.

An object of the present invention is to accurately form a microlens having a large height dimension and an aspherical surface.

Another object of the present invention is that the height dimension is large,
The objective is to obtain a photomask necessary for accurately forming a microlens whose surface is aspherical.

[0008]

The invention according to claim 1 is
In a method of manufacturing a microlens in which an uncured resin is dropped on a substrate and the dropped resin is cured on the substrate to form a hemispherical microlens, a photosensitive resin is used as the resin, and the substrate is The method includes an exposure step of exposing the cured photosensitive resin cured above in a hemispherical shape through a photomask having a transmittance distribution, and a developing step of developing the exposed portion of the cured photosensitive resin.

Therefore, since the uncured photosensitive resin is dropped onto the substrate to cure the photosensitive resin in a hemispherical shape, the height dimension of the cured photosensitive resin in a hemispherical shape can be increased. Becomes Furthermore, the cured photosensitive resin that has been cured into a hemispherical shape on the substrate is exposed through a photomask having a transmittance distribution, and then developed, so that the exposed surface of the cured photosensitive resin is transparent to the photomask. It is possible to obtain a microlens that is dissolved and removed according to the rate distribution, and has the surface of the cured photosensitive resin that has an aspherical shape. Moreover, since the dimension of the cured photosensitive resin that is dissolved and removed by exposure and development is small, a microlens with high accuracy can be obtained.

According to a second aspect of the present invention, there is provided a method for producing a microlens, wherein an uncured resin is dropped on a substrate, and the dropped resin is cured on the substrate to produce a hemispherical microlens. A variable volume resin whose volume is changed by exposure is used as the resin, and an exposure step of exposing through a photomask having a transmittance distribution to the cured volume variable resin which is hemispherically cured on the substrate is included. Characterize.

Therefore, since the uncured volume variable resin is dropped onto the substrate and the volume variable resin is cured into a hemispherical shape, the height dimension of the cured volume variable resin cured into a hemispherical shape can be increased. Becomes Further, by exposing the cured volume variable resin cured in a hemispherical shape on the substrate through a photomask having a transmittance distribution, the exposed surface side of the cured volume variable resin is adjusted according to the transmittance distribution of the photomask. It is possible to obtain a microlens whose volume is changed and whose surface of the cured volume variable resin has an aspherical shape.
Moreover, since the dimension of the cured volume variable resin whose volume is variable by exposure is small, a microlens with high accuracy can be obtained.

According to a third aspect of the present invention, in the method for producing a microlens according to the first aspect, the cured photosensitive resin that has been developed in the developing step is subjected to anisotropic dry etching to perform post-development. And transferring the shape of the cured photosensitive resin to the substrate.

Therefore, since the shape of the cured photosensitive resin whose surface is aspherical is transferred to the substrate by exposure and development, a microlens capable of handling wavelengths and temperatures which cannot be handled by the photosensitive resin is produced. can do.

According to a fourth aspect of the present invention, in the method for producing a microlens according to the second aspect, after the exposure is performed by performing anisotropic dry etching on the cured volume variable resin that has been exposed in the exposure step. And transferring the shape of the cured volume variable resin to the substrate.

Therefore, since the shape of the cured volume-variable resin whose surface is aspherical is transferred to the substrate by exposure, a microlens capable of handling wavelengths and temperatures that cannot be handled by the volume-variable resin is produced. You can

The invention according to claim 5 is the invention according to claims 1 to 4.
In the method for manufacturing a microlens according to any one of the above, a high wettability thin film forming step of forming a high wettability thin film having high wettability on a resin dropped on the substrate on the surface of the substrate, And a patterning step of patterning the wettable thin film according to the shape of the region where the resin is dropped.

Therefore, it is possible to control the spread of the dropped photosensitive resin or volume variable resin by forming a highly wettable thin film on the substrate and patterning the cured photosensitive resin or the cured photosensitive resin which is cured after the dropping. The height dimension of the cured volume variable resin can be further increased, the height dimension of the produced microlens can be further increased, and the precision of the microlens can be improved.

The present invention as defined in claim 6 is any one of claims 1 to 5.
In the method for manufacturing a microlens according to any one of the items, when the exposed photosensitive resin or the cured variable volume resin that has been dropped and cured on the substrate is exposed through the photomask, the cured A spacer having a height dimension larger than that of the photosensitive resin or the cured volume variable resin is sandwiched between the substrate and the photomask.

Therefore, the photomask does not come into contact with the cured photosensitive resin or the cured variable volume resin, and scratches of the cured photosensitive resin or the cured variable volume resin due to such contact are prevented. It Further, the distance between the cured photosensitive resin or the cured volume variable resin and the photomask is stably maintained, the exposure state to the cured photosensitive resin or the cured volume variable resin is stable, and Variations in shape can be suppressed.

The invention according to claim 7 is the invention according to claims 1, 3, and 5.
Or the method for producing a microlens according to any one of 6 above, wherein the photosensitive resin includes a design value of the microlens and a deviation amount of a shape between the hemispherical cured photosensitive resin cured on the substrate. The maximum value is "e", and the height dimension of the hemispherical cured photosensitive resin cured on the substrate is "t".
, The maximum depth dimension "d" affected by exposure
Is mixed with a dye that absorbs the exposed light so that “e ≦ d <t”.

Therefore, the exposed light is prevented from being reflected multiple times in the cured photosensitive resin to cause the standing wave effect, and the shape error of the microlens caused by the standing wave effect is reduced.

The invention according to claim 8 is the method for producing a microlens according to any one of claims 5 to 7, wherein the high wettability thin film is the cured photosensitive resin or the cured volume variable resin. Is characterized in that it has a property of absorbing light exposed to light.

Therefore, it is prevented that the exposed light is reflected multiple times in the cured photosensitive resin or the cured volume variable resin to cause the standing wave effect, and the standing wave effect causes the shape of the microlens. The error is reduced.

According to a ninth aspect of the photomask of the present invention, the size of the microlens is larger than that of the microlens by designing a microlens whose surface is an aspherical surface and dropping an uncured resin onto the substrate to cure the resin. A step of producing a hemispherical cured resin, a step of measuring the shape of the cured resin and comparing it with a design value of the microlens to determine the deviation amount of each part, and the transmittance according to the deviation amount of each part. And the step of determining the arrangement.

Therefore, when a microlens having an aspherical shape is produced based on a hemispherically cured resin as a base, a photomask suitable for exposing the cured resin can be obtained.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a first embodiment of the present invention.
Through 8 will be described. FIG. 1 is a process diagram showing a manufacturing process of a microlens, and FIGS. 2 to 8 are flowcharts, graphs and the like for explaining a manufacturing procedure of a photomask used for manufacturing a microlens.

First, as shown in FIG. 1A, a quartz substrate 1 which is a substrate is prepared, and a photoresist 3 which is an uncured photosensitive resin is formed on the quartz substrate 1 by using a microsyringe 2. Drop a predetermined amount. Here, by controlling the viscosity and the dropping amount of the photoresist 3, it is possible to control the shape of the photoresist 3 which becomes hemispherical by the surface tension after the dropping.

Before dropping the photoresist 3,
The surface of the quartz substrate 1 is thoroughly washed, and a primer treatment is performed if necessary. The main purpose of the cleaning of the quartz substrate 1 is to remove organic substances on the surface, and H ₂ SO ₄ and H ₂ O
A cleaning liquid in which ₂ and 1 were mixed at a ratio of 1: 1 was used. The primer treatment is a treatment for improving the wettability of the quartz substrate 1 with respect to the photoresist 3, and hexamethyldisilazane was used. The wettability of the quartz substrate 1 to the photoresist 3 is poor, and the dropped photoresist 3 has a substantially hemispherical shape, but the shape of the dropped photoresist 3 is controlled by controlling the wettability of the quartz substrate 1 by a primer treatment or the like. Can be changed to obtain the required shape. Note that this primer treatment may be unnecessary depending on the type of substrate and photosensitive resin used. Also, the case where the microsyringe 2 is used to control the dropping amount of the photoresist 3 has been described as an example, but in order to control the dropping amount of the photoresist 3 more accurately, the inside of the microcavity is The stored photoresist 3 may be ejected by driving the piezo element.

FIG. 1B shows a state in which the photoresist 3 dropped on the quartz substrate 1 is cured to form a cured photoresist 3a which is a hemispherical cured photosensitive resin. A bake treatment is effective for hardening the photoresist 3, and this bake treatment can be performed using a hot plate, an oven, or the like.

FIG. 1C shows the cured photoresist 3a.
2 shows an exposure process of exposing through a gray scale mask 4, which is a photomask having a transmittance distribution. An aligner or stepper can be used as the exposure device. Although details of the gray scale mask 4 will be described later, in order to prevent the surface of the cured photoresist 3a from being scratched at the time of exposure, the gray scale mask 4 is removed from the surface of the cured photoresist 3a.
It is desirable to carry out proximity exposure in a state in which the above are separated by several μm to several tens of μm. However, since the light incident on the gray scale mask 4 is not completely parallel light, the intensity of the light transmitted through the gray scale mask 4 slightly changes depending on the distance to reach the cured photoresist 3a. If this distance (distance between the gray scale mask 4 and the cured photoresist 3a) varies with each exposure, the shape of the cured photoresist 3a after exposure also changes, so the gray scale mask 4 and the cured photoresist 3a. In order to make the distance between the quartz substrate 1 and the cured photoresist 3a constant, a spacer 5 having a height slightly larger than that of the cured photoresist 3a is attached to the quartz substrate 1.
And grayscale mask 4 between them.

Here, the depth required to expose the cured photoresist 3a to light exposure corresponds to the amount of deviation between the target design value of the aspherical shape of the microlens and the shape of the cured photoresist 3a. The depth to do. This can be suppressed to about several% to several tens% of the height dimension of the cured photoresist 3a, depending on the design. Therefore, even if a microlens having a height of 100 μm is manufactured, a high-sensitivity photoresist is not necessary, and a photoresist having a low sensitivity of about several tens of μm even when it is applied thickly can be used. it can. For example, when exposing a flatly applied photoresist through a gray scale mask, a high sensitivity special photoresist that can be exposed at a thickness of 100 μm to make an aspherical lens having a height dimension of 100 μm. However, a photoresist having a thickness of about several tens of μm to be exposed can be used, and various photosensitive resins can be used according to the purpose.

FIG. 1D shows a state in which the exposure processing is performed through the gray scale mask 4 and then the development processing is performed. By this development treatment, the exposed portion of the cured photoresist 3a, which is hemispherical as shown by the broken line, is dissolved and removed, and the microlens 6 in which the surface of the cured photosensitive resin 3a has an aspherical shape can be obtained. it can.

Since the hardened photoresist 3a is formed by dropping and hardening the uncured photoresist 3, it is easy to increase the height of the hardened photoresist 3a. Micro lens 6
The height of the microlens 6 can be increased, and the surface of the microlens 6 can be formed into an aspherical shape.
Thereby, the microlens 6 having a large numerical aperture and a small aberration can be obtained. Further, since the size of the cured photosensitive resin 3a that is dissolved and removed by exposure and development is small,
It is possible to obtain the microlens 6 with high accuracy.

Next, the gray scale mask 4 will be described in detail. The gray scale mask 4 has a light transmittance distribution, and a method of giving a light transmittance distribution to the gray scale mask 4 is by irradiating a high energy beam such as an electron beam, which is commercially available from Canyon Materials, Inc. A method that uses a type of glass with a variable transmittance, or a large number of fine aperture patterns are placed on a normal chrome mask, and the size of the aperture is changed to change the amount of transmitted light per unit area, thus simulating There is a method of changing the transmittance. Since each has features such as ease of mask design and ease of handling fine patterns, it can be selected as necessary. Here, a type in which a large number of fine aperture patterns are arranged using a chrome mask generally used in photolithography of semiconductors and the like will be described. The number of gradations was 200.

FIG. 2 shows the manufacturing procedure of the gray scale mask 4.
A description will be given based on the flowchart. First, the microlens 6 which is an aspherical lens is designed (step S
1). The aspherical lens can be designed relatively easily by using a commercially available optical simulator. Here, an aspherical lens having a diameter of 600 μm and a height of 106 μm is used for an optical pickup. FIG. 3 is a graph showing design values of the designed microlens 6.

Then, a photoresist 3 in an amount suitable for producing the designed microlens 6 is dropped onto the quartz substrate 1 and cured to produce a cured photoresist 3a, and the cured photoresist 3a is produced. The shape of 3a is measured (step S2). FIG. 4 is a graph in which the shape of the cured photoresist 3a is shown by a solid line and the design value of the microlens 6 is shown by a broken line. Here, the shape of the hardened photoresist 3a needs to be a shape that can cover the entire microlens 6, that is, the outer dimension of the hardened photoresist 3a must be larger than the design value of the microlens 6.

Next, the amount of deviation between the shape of the cured photoresist 3a and the design value of the microlens 6 is obtained (step S3). FIG. 5 is a graph showing the deviation amount.
The maximum value of this deviation amount is 12 μm.

Then, the substrate coated with the photoresist is exposed using a gray scale test mask 7 in which 200 patterns of light transmittance are arranged in order as shown in FIG. 6, and the substrate is developed after the exposure. As a result, a transmittance-photoresist development depth conversion table as shown in FIG. 7 is created (step S4). FIG. 8 shows the transmittance of FIG.
It is the graph which showed the transmittance | permeability created based on the photoresist development depth conversion table, and the development depth of the photoresist. The exposure amount is set so that the depth of the exposed portion of the pattern having the highest transmittance is 12 μm or more. Since the difference between the shape of the hardened photoresist 3a and the design value of the microlens 6 is 12 μm, it is possible to manufacture a grayscale mask with an error of about 12 μm / 200 = 0.06 μm even with a grayscale mask of 200 gradations.

Next, the transmittance distribution of the gray scale mask is determined by referring to the deviation amount between the hardened photoresist 3a and the design value of the microlens 6 and the transmittance-photoresist development depth conversion table. (Step S5).
Then, the gray scale mask 4 that matches the determined transmittance distribution is manufactured (step S6), and the exposure processing shown in FIG. 1C is performed using the gray scale mask 4.

However, in the method of the present invention, since the thickness of the cured photoresist 3a is not uniform, the change in reflectance due to the change in the angle of the surface of the cured photoresist 3a,
Due to the effect of the standing wave effect generated by the light incident on the hardened photoresist 3a being multiple-reflected at the interface between the quartz substrate 1 and the hardened photoresist 3a and at the interface between the hardened photoresist 3a and the air. However, some errors may occur between the transmittance distribution given to the gray scale mask 4 and the shape of the cured photoresist 3a after exposure. In order to further improve the accuracy, the intensity distribution of the light incident on the cured photoresist 3a or the shape of the cured photoresist 3a after development is obtained by a simulation of photolithography in consideration of them and the design value is If an error has occurred, the transmittance may be changed so that it is corrected.

Next, a second embodiment of the present invention will be described with reference to FIG.
It will be described based on. Note that the same parts as those described in FIGS. 1 to 8 are denoted by the same reference numerals, and description thereof will be omitted (same in the following embodiments).

The method of manufacturing the microlens of this embodiment is substantially the same as the method of manufacturing the microlens of the first embodiment, except that the photoresist of which the first embodiment is a photosensitive resin is different. 3 is used, in the present embodiment, an acrylic resin 8 which is a volume variable resin whose volume changes by exposure is used.

As a method for producing a microlens using this acrylic resin 8, first, as shown in FIG. 9A, an uncured acrylic resin 8 is placed on a quartz substrate 1 using a microsyringe 2. Drop a fixed amount.

Next, as shown in FIG. 9B, the acrylic resin 8 dropped on the quartz substrate 1 is cured to form a hemispherical cured acrylic resin 8a.

Next, as shown in FIG. 9C, exposure processing is performed using the gray scale mask 4 described in the first embodiment. By this exposure processing, the volume of the cured acrylic resin 8a changes so as to decrease in accordance with the exposure amount, and the surface of the cured acrylic resin 8a has an aspherical shape as shown by the solid line in FIG. 9 (d). The lens 9 can be obtained.

Since the cured acrylic resin 8a is obtained by dropping and curing the uncured acrylic resin 8, the height dimension of the cured acrylic resin 8a can be increased, and The surface of the microlens 9 can be aspherical. Thereby, the microlens 9 having a large numerical aperture and a small aberration can be obtained. Moreover, since the dimension of the cured volume variable resin 8a whose volume is variable by exposure is small, the microlens 9 with high accuracy can be obtained.

Next, a third embodiment of the present invention will be described with reference to FIG.
A description will be given based on 0. In the present embodiment, as described in the first embodiment, anisotropic dry etching is performed on the hardened photoresist 3a on the quartz substrate 1 having the aspherical surface, and the hardened photoresist 3a is subjected to anisotropic dry etching. The shape is transferred to the quartz substrate 1. That is, FIGS. 10A to 10D are the same as FIGS. 1A to 1D.
10E shows the work process of anisotropic dry etching. As the anisotropic dry etching, an etching gas such as CF ₄ , C ₄ F ₈ or the like can be used.

As a result, a microlens 10 having the same shape as the microlens 6 described in the first embodiment but made of only the quartz substrate 1 is manufactured.

Here, the microlens 1 of the present embodiment
Since 0 is formed only from the quartz substrate 1 without including a photoresist as its material, it is possible to obtain the microlens 10 that can handle a wavelength and a temperature that cannot be handled by a photoresist.

In the present embodiment, as described in the first embodiment, the hardened photoresist 3a formed on the quartz substrate 1 and the surface of which has been made aspheric by exposure and development. Although the case where anisotropic etching is performed is described as an example, as described in the second embodiment, as described in the second embodiment, the surface is formed into an aspherical surface by the exposure process by being formed on the quartz substrate 1. Cured acrylic resin 8a
By performing anisotropic etching on, a microlens made of only the quartz substrate 1 can be similarly prepared.

Next, a fourth embodiment of the present invention will be described with reference to FIG.
It will be described based on 1. This embodiment is an embodiment in which a treatment for improving the wettability between the quartz substrate 1 and the photoresist 3 is added to the first embodiment.

First, as shown in FIG. 11A, a highly wettable thin film 11 having high wettability with respect to the photoresist 3 is formed on the surface of the quartz substrate 1.

Next, as shown in FIG. 11B, patterning is performed on the high wettability thin film 11 to leave the high wettability thin film 11 only in the region where the photoresist 3 is dropped, and to increase the height of other regions. The wettable thin film 11 is removed.

Then, as shown in FIG. 11C, by dropping the photoresist 3 on the patterned high wettability thin film 11 remaining on the quartz substrate 1, the dropped photoresist 3 is patterned. It fits in the formed high wettability thin film 11.

As the work process after FIG. 11C, FIG. 1B to FIG. 1D described in the first embodiment or FIG. 10B described in the third embodiment. b) to FIG.
Same as (e).

In the present embodiment, since the bottom surface of the dropped photoresist 3 is the same as the patterned high wettability thin film 11, the diameter of the dropped photoresist 3 can be easily controlled, and the dropping amount can be further improved. The height dimension of the photoresist 3 dropped by increasing the
It can be higher than when there is no 1 and, by extension,
It is easy to control the diameter and height of the microlens,
The dimensional accuracy of the manufactured microlens can be improved.

Next, a fifth embodiment of the present invention will be described with reference to FIG.
It will be described based on 2. In FIG. 12, the broken line shows the design value of the microlens 6 described in the first embodiment, and the solid line shows the shape of the hemispherical cured photoresist 3a.

Here, the maximum value of the deviation between the design value of the microlens 6 and the hardened photoresist 3a is "e", and the height dimension of the hardened photoresist 3a is "t".
, The maximum depth dimension "d" affected by exposure
However, a dye that absorbs the exposed light so that “e ≦ d <t” is mixed in the photoresist 3.

Further, as the high wettability thin film 11 formed on the surface of the quartz substrate 1, one having a property of absorbing light exposed to the cured photoresist 3a is used.

Therefore, it is prevented that the exposed light is reflected multiple times in the cured photoresist 3a to cause the standing wave effect, and the shape error of the microlens 6 caused by the standing wave effect is reduced. .

In this embodiment, the case where the hardened photoresist 3a is used has been described, but the case where the hardened acrylic resin 8a as described in the second embodiment is used is also exposed. Similar effects can be obtained by mixing a light absorbing dye with the acrylic resin 8 or by using the highly wettable thin film 11 having the property of absorbing the light obtained by exposing the cured acrylic resin 8a.

Next, a sixth embodiment of the present invention will be described with reference to FIG.
It will be described based on 3. The present embodiment shows an objective lens 12 for an optical pickup head using the microlens of the present invention.

The objective lens 12 is formed by bonding two aspherical microlenses 12a and 12b produced by the method described in the third embodiment,
The numerical aperture is increased to 0.85.

By using the objective lens 12 of this embodiment, it is possible to manufacture a minute pickup head having a high numerical aperture.

[0065]

According to the method of manufacturing a microlens of the invention described in claim 1, the cured photosensitive resin cured in a hemispherical shape on the substrate is exposed through a photomask having a transmittance distribution, By developing thereafter, the exposed surface side of the cured photosensitive resin is dissolved and removed according to the transmittance distribution of the photomask, and a microlens having the surface of the cured photosensitive resin as an aspherical shape can be obtained, and Since the size of the cured photosensitive resin that is dissolved and removed by exposure and development is small, it is possible to obtain an accurate microlens.

According to the method for producing a microlens of the second aspect of the present invention, the cured volume variable resin cured in a hemispherical shape on the substrate is exposed through a photomask having a transmittance distribution to cure the resin. The exposed surface side of the variable volume resin changes its volume according to the transmittance distribution of the photomask,
It is possible to obtain a microlens in which the surface of the cured volume variable resin has an aspherical shape, and moreover, since the dimension of the cured volume variable resin whose volume is changed by exposure is small, an accurate microlens can be obtained. it can.

According to the invention described in claim 3, in the method for producing a microlens according to claim 1, after the development, the cured photosensitive resin developed in the developing step is subjected to anisotropic dry etching. Since the shape of the cured photosensitive resin of 1 is transferred to the substrate, it is possible to manufacture a microlens that can handle wavelengths and temperatures that cannot be handled by the photosensitive resin.

According to the invention described in claim 4, in the method for producing a microlens according to claim 2, after the exposure, the cured volume variable resin exposed in the exposure step is subjected to anisotropic dry etching. Since the shape of the cured variable volume resin is transferred to the substrate, it is possible to manufacture a microlens that can handle wavelengths and temperatures that cannot be handled by the variable volume resin.

According to a fifth aspect of the present invention, in the method for producing a microlens according to any one of the first to fourth aspects, a high wettability thin film having high wettability with respect to the resin dropped on the substrate is formed. Since it has a high wettability thin film forming step of forming on the surface of the substrate and a patterning step of patterning the high wettability thin film according to the shape of the region where the resin is dropped, it is dropped by the patterned high wettability thin film The spread of the resin or the volume variable resin can be controlled, and the height dimension of the cured photosensitive resin or the cured volume variable resin cured after dropping can be made larger, and the height of the microlens to be produced can be increased. The size can be increased and the precision of the microlens can be improved.

According to the invention of claim 6, in the method for producing a microlens according to any one of claims 1 to 5, a cured photosensitive resin or a cured variable volume resin dropped and cured on a substrate. On the other hand, when exposing through a photomask, a spacer with a height dimension larger than that of the cured photosensitive resin or cured volume variable resin is sandwiched between the substrate and the photomask, The photomask does not come into contact with the photosensitive resin or the cured variable volume resin, and the scratch of the cured photosensitive resin or the cured variable volume resin due to such contact can be prevented. The distance between the resin or the cured variable volume resin and the photomask can be maintained stably, and the exposure state for the cured photosensitive resin or the cured volume variable resin is stabilized to produce. It is possible to suppress variations in the shape of microlenses.

According to the invention of claim 7, claim 1,
In the method for producing a microlens according to any one of 3, 5, or 6, the photosensitive resin includes a design value of the microlens and a deviation amount of a shape between the hemispherical cured photosensitive resin cured on the substrate. When the maximum value is “e” and the height dimension of the hemispherical cured photosensitive resin cured on the substrate is “t”, the maximum depth dimension “d” affected by exposure is “e ≦ d”. <
Since the dye that absorbs the exposed light is mixed so as to be t ″, it is possible to prevent the exposed light from being multiple-reflected in the cured photosensitive resin to cause the standing wave effect. The shape error of the microlens caused by the wave effect can be reduced.

According to the eighth aspect of the invention, in the microlens manufacturing method according to any one of the fifth to seventh aspects, the high wettability thin film is a cured photosensitive resin or a cured volume variable resin. Since it has the property of absorbing exposed light, it is possible to prevent the standing light effect from being caused by multiple reflection of the exposed light in the cured photosensitive resin or cured volume variable resin, and the standing wave effect is caused. It is possible to reduce the shape error of the microlens.

The photomask according to the ninth aspect is larger than the microlenses by the step of designing a microlens whose surface is an aspherical surface and dropping an uncured resin onto the substrate to cure the resin. A step of producing a hemispherical cured resin, a step of measuring the shape of the cured resin and comparing it with a design value of the microlens to determine the deviation amount of each part, and the transmittance according to the deviation amount of each part. Since it was produced by the process of determining the arrangement, a photo suitable for exposing the cured resin when making an aspherical microlens based on the cured resin cured in a hemisphere shape. You can get a mask.

[Brief description of drawings]

FIG. 1 is a process drawing showing a manufacturing process of a microlens according to a first embodiment of the present invention.

FIG. 2 is a flowchart illustrating a procedure for manufacturing a gray scale mask.

FIG. 3 is a graph showing design values of microlenses to be manufactured.

FIG. 4 is a graph showing a comparison between a design value of a microlens to be manufactured and a shape of a cured photoresist which is a base of the microlens.

FIG. 5 is a graph showing a deviation amount between a design value of a microlens to be manufactured and a shape of a cured photoresist which is a base of the microlens.

FIG. 6 is a plan view showing a grayscale test mask.

FIG. 7 is a transmittance-photoresist development depth conversion table.

FIG. 8 is a graph showing the relationship between transmittance and photoresist development depth.

FIG. 9 is a process chart showing a process of manufacturing a microlens according to a second embodiment of the present invention.

FIG. 10 is a process drawing showing a process of manufacturing a microlens according to a third embodiment of the present invention.

FIG. 11 is a process drawing showing part of the process of manufacturing the microlens according to the fourth embodiment of the present invention.

FIG. 12 is a sectional view showing a fifth embodiment of the present invention.

FIG. 13 is a sectional view showing an objective lens according to a sixth embodiment of the present invention.

[Explanation of symbols]

1 substrate 3 Photosensitive resin 3a Cured photosensitive resin 4 photo mask 5 spacers 6, 9, 10 micro lens 8 variable volume resin 8a Cured variable volume resin 11 High wettability thin film

Claims (9)

[Claims] 1. An uncured resin is dropped onto a substrate,
In a method for producing a microlens, in which a dropped resin is cured on the substrate to produce a hemispherical microlens, a photosensitive resin is used as the resin, and the cured photosensitive resin is hemispherically cured on the substrate. A method of manufacturing a microlens, comprising: an exposure step of exposing through a photomask having a transmittance distribution with respect to, and a development step of developing an exposed portion of the cured photosensitive resin. 2. An uncured resin is dropped onto a substrate,
In a method of manufacturing a microlens in which a dripped resin is cured on the substrate to form a hemispherical microlens, a variable volume resin whose volume is changed by exposure is used as the resin, and the resin is cured into a hemispherical shape on the substrate. And a step of exposing the cured volume variable resin through a photomask having a transmittance distribution, to produce a microlens. 3. A step of transferring the shape of the cured photosensitive resin after development to the substrate by performing anisotropic dry etching on the cured photosensitive resin after being developed in the developing step. The method for producing a microlens according to claim 1, characterized in that the method comprises: 4. A step of transferring the shape of the cured volume variable resin after exposure to the substrate by performing anisotropic dry etching on the cured volume variable resin after being exposed in the exposure step. The method for producing a microlens according to claim 2, characterized in that it has. 5. A high wettability thin film forming step of forming a high wettability thin film having high wettability on a resin dropped onto the substrate on the surface of the substrate, and dropping the resin onto the high wettability thin film. The patterning process of patterning according to the shape of the area | region to perform, The manufacturing method of the micro lens as described in any one of Claim 1 thru | or 4 characterized by the above-mentioned. 6. The cured photosensitive resin or the cured volume when the cured photosensitive resin or the cured variable volume resin that is dropped and cured on the substrate is exposed through the photomask. 6. The method for manufacturing a microlens according to claim 1, wherein a spacer having a height larger than that of the variable resin is sandwiched between the substrate and the photomask. 7. The photosensitive resin has a design value of a microlens and a maximum value of a deviation amount of a shape of the hemispherical cured photosensitive resin cured on the substrate from “e”, When the height dimension of the cured photosensitive resin in a hemispherical shape cured by 1. is set to be "t", exposure is performed so that the maximum depth dimension "d" affected by the exposure is "e≤d <t". 7. The method for producing a microlens according to claim 1, wherein a dye that absorbs the generated light is mixed. 8. The high wettability thin film has a property of absorbing light exposed to the cured photosensitive resin or the cured volume variable resin, according to any one of claims 5 to 7. Method for manufacturing a microlens. 9. A step of designing a microlens whose surface is an aspherical shape, and a hemispherical cured resin larger than the microlens are produced by dropping an uncured resin onto a substrate and curing the resin. It is produced by a step, a step of measuring the shape of the cured resin and comparing it with a design value of the microlens to obtain a deviation amount of each part, and a step of determining a transmittance arrangement according to the deviation amount of each part. A photo mask that is characterized.