JPH1148354A - Method for working microlens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for working to accurately manufacture a microlens having a curved surface. SOLUTION: At a first step, photosensitive resin material 30 on a base 20 is exposed by using a first mask 10 having a circular light shielding pattern 11, and an exposed part is removed to form a cylindrical lens substrate 31 on the base 20. At a second step, the substrate 31 is exposed to introduce a light obliquely by using a second mask 40, and repeatedly exposed while altering a light introducing angle, and a periphery of the substrate 31 is gradually removed to form a convex polygonal protrusion above near a shape of the microlens on the base 20. At a third step, the protrusion on the base 20 is heated to be contracted to form a periphery of the protrusion in a curved surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a processing method for accurately manufacturing a microlens having a curved surface.

[0002]

2. Description of the Related Art In the communication field, an element having a plurality of microlenses 60 as shown in FIG. 8 is used for condensing a fiber connector. Each micro lens 6
Reference numeral 0 denotes a spherical surface or an aspherical surface, for example, having a diameter of 200 μm and a height of 40 μm. In a fiber connector using such a microlens, the shape and surface roughness of the microlens affect the light-collecting performance, and thus determine the transmission efficiency of the fiber connector.

[0003]

Conventionally, the above-mentioned microlenses have been manufactured by engraving a mold with a thin bite, and pouring a resin or glass into the mold. However, there is a limit to the size of a lens that can be engraved with a cutting tool, and the shape is also limited. Further, cutting marks remained on the surface of the microlens manufactured in this manner, and the precision was poor.

On the other hand, SR (synchrotron radiation)
A processing method by an exposure technique using light or laser light has been proposed. This proposal is based on Forschungs
zentrum Karlsrluhe Techni
k und Umwelt ”(Print aus
den NACHRICHTEN, Forschu
ngszentrum Karlsrluhe Jah
rgang 27, Vol. 2-3, 1995, 155
-164). However, even with this processing method, the shape of the microlens that can be processed is limited, and the shape accuracy is low.

Accordingly, an object of the present invention is to provide a processing method capable of accurately manufacturing a microlens having a curved surface.

Another object of the present invention is to provide a processing method capable of simultaneously manufacturing a large number of microlenses having a curved surface with high accuracy.

[0007]

According to a first aspect of the present invention, a photosensitive resin material on a substrate is exposed by using a first mask having a circular or polygonal mask pattern. A first step of forming a cylindrical or polygonal column-shaped lens substrate on the substrate by removing the substrate, and a second mask in which the relative positional relationship between the substrate and the substrate is variable. The exposure is performed such that light enters, and the exposure is repeated while changing the angle of entry of the light, thereby gradually removing the periphery of the lens substrate and projecting upward on the substrate close to the shape of the microlens. A second step of forming a polygonal projection, and a third step of heating and shrinking the projection on the substrate to make the periphery of the projection a curved surface. The method is provided .

The exposure in the first and second steps is preferably performed using SR (synchrotron radiation) light or excimer laser light.

The exposure in the second step is performed by changing an angle of the substrate with respect to the second mask and rotating the substrate about a central axis of the lens base.

Further, in the exposure in the second step, a mask having a slit-shaped transmission pattern is used as the second mask, and the exposure is performed so that light enters the transmission pattern obliquely to the mask. Further, it may be performed by changing the angle of entry of light by changing the position of the transmission pattern of the mask with respect to the lens substrate.

According to the second aspect, the photosensitive resin material on the substrate is exposed using the first mask having a plurality of circular or polygonal mask patterns, and the exposed portions are removed. A first step of forming a plurality of cylindrical or polygonal lens bodies at predetermined intervals on the substrate, and a relative positional relationship between the first step and the substrate being variable, corresponding to the plurality of lens bodies; Using a second mask having a plurality of slit-shaped transmission patterns, each of the plurality of lens substrates is exposed so that light enters in the oblique direction at the same angle, and the exposure is performed while changing the entering angle of the light. Is repeated, thereby gradually removing the corners on one side of the plurality of lens bases. Hereinafter, this is performed three times by rotating the second mask by 90 ° in the plane thereof, thereby obtaining the plurality of lens bases. Lens base A second step of gradually removing the four corners, and a third step in which a relative positional relationship between the substrate and the substrate is variable and a plurality of slit-shaped transmission patterns corresponding to the plurality of lens substrates are provided. Each of the plurality of lens substrates is exposed by using a mask so that light enters the diagonal directions at the same angle, and the exposure is repeated while changing the angle of entry of the light. The angle that forms an angle of 45 ° with the side is gradually removed, and this is performed three times by rotating the third mask 90 ° at a time in the plane to thereby remove the four angles of the plurality of lens substrates. A third step of gradually removing four corners between to form a plurality of upwardly convex polygonal projections close to the shape of the microlens on the substrate; By heating and shrinking it A fourth step and a processing method of a microlens, which comprises a to the periphery of the projection les curved surface is provided.

[0012] In the second invention, the first and the second are also provided.
The exposure in the step is preferably performed using SR (synchrotron radiation) light or excimer laser light.

In the second aspect of the present invention, the light entering angles in the exposure in the second step and the third step are adjusted by changing the positions of the second mask and the third mask, respectively. Is preferably performed.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below. First, a case in which one micro lens is processed will be described.

In FIG. 1A, a photosensitive resin material 30 on a substrate 20 is exposed through a first mask 10 having a circular light-shielding pattern 11. As the resin material 30, for example, PMMA is preferable, and as a light source for exposure, SR light (synchrotron radiation light) or excimer laser light is preferable. PMMA exhibits photosensitivity, and a part irradiated with SR light or excimer laser light causes a chemical reaction, and the part having caused the chemical reaction can be removed by a solvent. As a result, a cylindrical lens base 31 is formed on the substrate 20.

FIG. 2 shows an example of the first mask 10, and the light-shielding pattern 11 is formed by, for example, applying gold plating.
FIG. 2 shows a mask for forming one microlens. However, when forming a large number of microlenses to be described later, the number of light-shielding patterns 11 may be increased.

In FIG. 1B, a second mask 40 is used in place of the first mask 10 to perform exposure for tilting the substrate 20 to remove corners of the lens base 31. In this exposure, the exposure for removing the periphery of the lens body 31 is performed by intermittently rotating the substrate 20 by a predetermined angle 360 degrees without changing the tilt angle of the substrate 20. FIG. 1C shows a state in which the substrate 20 has been rotated by 180 degrees from the state of FIG. 1B, and the hatched portion indicates an exposed area. In FIGS. 1B and 1C, broken lines indicate the final shape of the microlens to be processed. FIG. 3 shows an example of the second mask 40, and a light-shielding pattern 41 formed by gold plating or the like is formed in a half area.

1 (b) and 1 (c) are repeated a plurality of times while changing the inclination angle of the substrate 20. That is, as the inclination angle is increased, it is possible to perform exposure for removing the portion left at the top in the state of FIG.

FIG. 1D is an enlarged view of a processed shape obtained by repeating the processes of FIGS. 1B and 1C three times and then dissolving and removing the exposed portion with a solvent. A processed shape with a corner which is close to the shape of the microlens to be processed indicated by is obtained.

Next, in the state shown in FIG.
Is heated, the PMMA tends to contract due to surface tension, so that the shape becomes close to the target spherical surface. If this is cooled, a microlens having a target spherical surface is manufactured with high accuracy.
The heating temperature and time are, for example, about 50 to 80 ° C. for about several minutes.

Here, a microlens having a spherical surface has been described as an example. However, the processing method according to the present invention can select any curved surface as long as it is a convex curved surface by appropriately selecting the inclination angle of the substrate 20 described in FIG. It is possible to manufacture a lens having an arbitrary size within a limited range of a light source such as a mask, SR light, or excimer laser light.

According to the processing method of the present invention, it is possible to provide a microlens capable of realizing a shape precision of sub-μm and a surface roughness of several tens nm and achieving high transmission efficiency.

The completed PMMA microlens is Ni
It is a material that is easy to plate. If a female mold is manufactured by plating, and plastic or glass is molded based on this, mass production is possible.

Next, an embodiment for simultaneously processing a plurality of microlenses will be described with reference to FIGS. Here, an example in which nine micro lenses are simultaneously processed will be described. As the first mask in this example, as described with reference to FIG. 2, a mask in which nine circular light-shielding patterns are formed at equal intervals is used. As a result, FIG.
By the same steps as described above, nine cylindrical lens substrates 31 can be simultaneously formed on the substrate 20.

The second mask 50 is different from that of FIG. 3 in that it has nine slit-shaped transmission portions 51 corresponding to each of the nine lens substrates 31. Also, the light for exposure is made to enter obliquely, not directly above the second mask 50.

Using such a second mask 50, the transmission portion 51 is disposed so as to be located on the right side of the lens body 31 as shown in FIG. 4, and the lens is formed as shown in FIG. Exposure is performed to remove the upper left corner of the base 31 in the figure. This exposure is performed a plurality of times by shifting the second mask 50 in the X direction (the substrate 20 may be used, but in this case, the opposite direction). FIG. 5B shows the second exposure, and FIG.
(C) shows the third exposure. Each exposure is performed at a different incident angle. That is, the incident angle is gradually increased such that the first time is the incident angle θ ₁ , the second time is the incident angle θ ₂ , and the third time is the incident angle θ ₃ .

Next, exposure for removing the upper right corner of the lens substrate 31 shown in FIG. 5A is performed. this is,
The second mask 50 is shifted from the state shown in FIG. 5A so that the transmission part 51 is located on the left side of the lens body 31.
Exposure similar to that in FIGS. 5A, 5B, and 5C is performed at the incident angle θ.
_1, θ _2, carried out in the θ _3.

Next, exposure for removing upper corners on both the upper and lower sides of the lens substrate 31 shown in FIG. 4 is performed. In this case, the second mask 50 is rotated, for example, 90 ° counterclockwise from the state shown in FIG. 4 so that the transmission portion 51 is positioned above the lens body 31. Then, FIGS. 5 (a), (b),
Exposure similar to (c) is performed at incident angles θ ₁ , θ ₂ , θ ₃ . As a result, the upper corner on the lower side of the lens base 31 shown in FIG. 4 is removed. Thereafter, exposure for removing the upper upper corner of the lens substrate 31 shown in FIG. 4 is performed.
This is because, in FIG.
Is positioned below the lens base 31. Exposure similar to that shown in FIGS. 5A, 5B, and 5C is performed at incident angles θ ₁ , θ ₂ , and θ ₃ . As a result, the upper upper corner of the lens base 31 shown in FIG. 4 is removed.

Further, exposure is performed to remove the diagonally upper right, diagonally lower right, diagonally upper left, and diagonally lower left corners of the lens substrate 31 shown in FIG. For this purpose, a third mask 55 as shown in FIG. 6 is used. The third mask 55 is provided with nine transmission portions 56 at an equal angle of 45 °. The arrangement of the third mask 55 shown in FIG. 6 is an arrangement for removing a diagonally upper left corner of the lens base 31 ′ from which the left, right, upper and lower corners have been removed. From this state, the third mask 55
5A, while shifting in the direction of arrow A in FIG.
Exposure similar to (b) and (c) is performed with incident angles θ ₁ , θ ₂ , θ
Perform in ₃ . As a result, the upper left corner of the lens base 31 'shown in FIG. 6 is removed.

Next, the third mask 55 is applied to each transmission section 56.
Is positioned diagonally above and to the left of the lens base 31 '. While shifting the third mask 55 in the direction of arrow B in the figure from this state, exposure similar to that shown in FIGS. 5A, 5B and 5C is performed at incident angles θ ₁ , θ ₂ and θ ₃ . As a result, FIG.
The lower right corner of the lens base 31 ′ shown in FIG.

Next, in order to remove the lower left corner of the lens base 31 ′, the third mask 55 is applied to each of the transmitting portions 56.
Is rotated 90 ° from the state of FIG. 6 so that is positioned diagonally to the right of the lens base 31 ′. While shifting the third mask 55 from this state in the direction of arrow C in the figure, FIG.
Exposure similar to (b) and (c) is performed with incident angles θ ₁ , θ ₂ , θ
Perform in ₃ . As a result, the lower left corner of the lens base 31 'shown in FIG. 6 is removed.

Further, in order to remove the upper right corner of the lens base 31 ′, the third mask 55 is attached to each of the transmitting portions 56.
Is positioned diagonally below and to the left of the lens base 31 ′. While shifting the third mask 55 in the direction of arrow D in the drawing from this state, the same exposure as in FIGS. 5A, 5B and 5C is performed at the incident angles θ ₁ , θ ₂ and θ ₃ . As a result, FIG.
The upper right corner of the lens substrate 31 'shown in FIG.

In this manner, the left and right of the lens body 31
By removing the upper, lower, diagonally upper right, diagonally lower right, diagonally upper left, and diagonally lower left corners, the cross-sectional shape at a certain height position of the lens substrate 31 becomes a broken line around the polygon as shown in FIG. The portion is removed to obtain the shape as described in FIG. Therefore, when the substrate 20 is heated, each lens base 31 ′ tends to contract due to surface tension, resulting in a shape close to the target spherical surface. When this is cooled, nine microlenses of the target spherical surface are simultaneously manufactured with high accuracy.

As shown in FIG. 4, when the distance L2 between the lens bases 31 to be processed becomes small, the upper part of the lens bases becomes almost flat even when exposure is performed. In addition, a certain lens base is exposed to light from a transmission part for an adjacent lens base. To prevent this, the interval L2 between the lens substrates 31 to be processed needs to be larger than the diameter L1 of the microlenses.

[0035]

As described above, according to the present invention, a microlens having a curved surface can be manufactured with high accuracy. In addition, a large number of microlenses having a curved surface can be manufactured simultaneously with high accuracy, and a microlens capable of achieving high transmission efficiency for a fiber connector can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a process in processing one microlens according to the present invention.

FIG. 2 is a plan view showing a first mask used in the step shown in FIG.

FIG. 3 is a plan view showing a second mask used in the step shown in FIG. 1 (b).

FIG. 4 is a view for explaining a mask for a second step when a plurality of micro lenses are simultaneously processed according to the present invention.

FIG. 5 is a view for explaining a flow of a second step using the mask shown in FIG. 4;

FIG. 6 is a view for explaining a mask for a third step when a plurality of micro lenses are simultaneously processed according to the present invention.

FIG. 7 is a view for explaining a flow of a third step using the mask shown in FIG. 6;

FIG. 8 is a diagram for explaining a microlens for a fiber connector to which the present invention is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Mask 11, 41 Light-shielding pattern 20 Substrate 30 Photosensitive resin material 31 Lens base 40, 50 Second mask 51, 56 Transmissive part 55 Third mask

Claims (8)

[Claims] An exposure is performed on a photosensitive resin material on a substrate using a first mask having a circular or polygonal mask pattern, and the exposed portion is removed to form a columnar or polygonal column on the substrate. A first step of forming a lens base, and performing exposure such that light enters the lens base in an oblique direction using a second mask having a variable relative positional relationship with the substrate, A second step of gradually removing the periphery of the lens base and forming an upwardly convex polygonal projection close to the shape of the microlens on the substrate by repeating exposure while changing the angle of incidence of light. And a third step of heating and shrinking the projections on the substrate to make the periphery of the projections a curved surface. 2. The method of processing a microlens according to claim 1, wherein the exposing in the first and second steps includes:
A method of processing a microlens, wherein the method is performed using SR (synchrotron radiation) light or excimer laser light. 3. The microlens processing method according to claim 2, wherein the exposure in the second step is performed by the second step.
Wherein the angle of the substrate with respect to the mask is changed, and the substrate is rotated about a central axis of the lens base. 4. The microlens processing method according to claim 2, wherein the exposure in the second step is performed by the second step.
Using a mask having a slit-shaped transmission pattern as a mask, performing exposure so that light enters obliquely to the transmission pattern of the mask, and changing the position of the transmission pattern of the mask with respect to the lens substrate. A method of processing a microlens, wherein the method is performed by changing a light entering angle according to the method. 5. A photosensitive resin material on a substrate is exposed using a first mask having a plurality of circular or polygonal mask patterns. A first step of forming a plurality of cylindrical or polygonal columnar lens substrates at intervals; and a plurality of slit-shaped corresponding to the plurality of lens substrates, wherein a relative positional relationship with the substrate is variable. By using a second mask having a transmission pattern, each of the plurality of lens substrates is subjected to exposure such that light enters in an oblique direction at the same angle, and the exposure is repeated while changing the angle of entry of the light, whereby the The corners on one side of the plurality of lens bases are gradually removed, and thereafter, this is performed three times by rotating the second mask by 90 ° in the plane thereof to thereby obtain four corners of the plurality of lens bases. Gradually A second step of removing; and a third mask having a plurality of slit-shaped transmission patterns corresponding to the plurality of lens substrates, wherein a relative positional relationship between the plurality of lens substrates is variable. Each of the lens bases is exposed so that light enters in the oblique direction at the same angle, and the exposure is repeated while changing the light entrance angle, whereby the one side of the plurality of lens bases is
The angle forming the angle of 5 ° is gradually removed, and the angle is then reduced by rotating the third mask by 90 ° in its plane at 3 °.
The fourth step is to gradually remove four corners between the four corners of the plurality of lens bases to form a plurality of upwardly convex polygonal projections close to the shape of the microlenses on the substrate. 3. A microlens processing method, comprising: a third step; and a fourth step of heating and shrinking the plurality of protrusions on the substrate to make the periphery of each protrusion a curved surface. 6. The method for processing a microlens according to claim 5, wherein the exposing in the first and second steps comprises:
A method of processing a microlens, wherein the method is performed using SR (synchrotron radiation) light or excimer laser light. 7. The method for processing a microlens according to claim 6, wherein the angle of entry of light in the exposure in the second step is adjusted by changing a position of the second mask. Micro lens processing method. 8. The method for processing a microlens according to claim 7, wherein the angle of entry of light in the exposure in the third step is adjusted by changing a position of the third mask. Micro lens processing method.