JP2007219343A - Manufacturing method of microlens and manufacturing method of microstructure body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of microlens having an accurate shape. <P>SOLUTION: The manufacturing method of microlens has steps of: developing a resist layer formed on a substrate; forming a resist pattern of cylinder shapes; thereafter melting the resist by heat flow to make lens shapes; and further treating the remaining resist and the substrate by dry-etching to transfer the shapes of the resist to the substrate, wherein, at the starting point of the dry etching, the resist height (SAG amount) of the resist shapes 4 formed by heat flow is set to be lower than the height of the resist layer formed on a region 5 where the resist pattern is not formed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a microlens manufacturing method and a microstructure manufacturing method.

  As one of the methods for manufacturing a microlens, a resist is applied on a substrate such as quartz, and the resist is exposed and developed using a simple binary mask in which an opening is provided in a chromium light-shielding portion to form a cylindrical shape. Thereafter, a method is known in which the resist is formed into a lens shape by heat flow, and the remaining resist and the substrate are simultaneously dry-etched to transfer the resist shape to the substrate, thereby producing a microlens on the surface of the substrate.

  In such a microlens manufacturing method, the etching selectivity between the resist and the substrate (substrate etching rate / resist etching rate) becomes a problem. That is, it is necessary to determine the shape of the resist formed by heat flow in consideration of the etching selectivity so that the target microlens shape can be obtained at the end of etching.

  FIG. 8 shows an example of the etching selectivity pattern in the radial direction of the microlens. (A) is the case where the etching selectivity does not change in the radial direction, and is the most ideal case. (B) is a case where the rate of change of the etching selectivity ratio in the lens radial direction is constant. Even in this case, if the rate of change is known in advance, the resist shape can be determined in consideration thereof.

  (C) is a case where the rate of change of the etching selectivity changes in the lens radial direction, and in many cases, the way of change is not uniform. Therefore, in such a case, there is a problem that even if the resist having the same shape is dry-etched, the shape of the microlens formed on the substrate surface is different.

  The present invention has been made in view of such circumstances, and develops a resist layer formed on a substrate to form a cylindrical resist pattern, and then melts the resist by heat flow to form a lens shape. And a method of manufacturing a microlens having an accurate shape, further comprising a step of dry etching the remaining resist and the substrate to transfer the shape of the resist to the substrate. And a substrate and a resist pattern having a shape corresponding to a desired shape to be formed on the substrate, and the resist pattern and the substrate are dry-etched to transfer the resist pattern to the substrate PROBLEM TO BE SOLVED To provide a method for manufacturing a fine structure having a precise shape, which is a method for manufacturing a fine structure having a process To.

  The first means for solving the problem is to develop a resist layer formed on the substrate to form a cylindrical resist pattern, and then melt the resist by a heat flow into a lens shape. A method of manufacturing a microlens comprising a step of dry etching the remaining resist and the substrate to transfer the shape of the resist to the substrate, wherein the microlens is formed by heat flow at the start of the dry etching. A method of manufacturing a microlens, characterized in that the height of the lens-shaped resist (SAG amount) is lower than the height of the resist layer existing in the region where the lens-shaped resist pattern is not formed.

  As a result of investigating the reason why the etching selectivity becomes as shown in FIG. 8C, the inventor found that the resist in the region where the resist pattern is not formed, that is, the region around the region where the cylindrical resist pattern is formed. I found out that it was the cause. Normally, no exposure is performed in this region, and the resist remains as it is over a considerably large area.

  When dry etching progresses and reaches a certain stage, the resist in this region disappears all at once and the substrate surface is exposed. Then, when the substrate is quartz or glass, oxygen is generated from the substrate, and the composition of the etching gas is changed. For this reason, the etching selectivity greatly changes at this point. When the substrate is a resin, the resin sucks oxygen and changes the composition of the etching gas. For this reason, the etching selectivity greatly changes at this point.

  In any case, the etching selectivity changes rapidly when the resist in the region where the resist pattern is not formed disappears by etching. This leads to a change in the etching selectivity in the radial direction of the microlens, and FIG. Etching selectivity as shown in FIG.

Therefore, in this means, at the start of dry etching, the height of the lens-shaped resist (SAG amount) formed by the heat flow is set to the area of the resist layer existing in the region where the lens-shaped resist pattern is not formed. I try to make it lower than the height. As a method of making the height of the lens-shaped resist (SAG amount) lower than the height of the resist layer formed in the region where the resist pattern is not formed, for example, even in a place where a cylindrical resist pattern is formed, On the other hand, the region where the resist pattern is not formed may be left unexposed.
In this case, when dry etching of the region where the microlens is formed is completed, the resist still remains in the region where the resist pattern is not formed, and the sudden change in the etching rate as described above occurs. Can be prevented. Therefore, an etching selectivity pattern as shown in FIGS. 8A and 8B can be obtained, and a microlens having an accurate shape can be manufactured.

  The second means for solving the above problem is to develop a resist layer formed on the substrate to form a cylindrical resist pattern, and then melt the resist to form a lens by heat flow. A method of manufacturing a microlens comprising a step of dry-etching the remaining resist and the substrate and transferring the shape of the resist to the substrate, wherein the lens-shaped resist pattern is formed at the start of the dry etching. A method of manufacturing a microlens, characterized in that a resist layer is not formed in a region that is not formed.

  In this means, contrary to the first means, the resist layer is not formed in the region where the lens-shaped resist pattern is not formed at the start of dry etching. This can be easily realized, for example, by exposing a region where a resist pattern is not formed. In this way, in the region where the resist pattern is not formed, the substrate is exposed from the beginning, and the etching selectivity does not change suddenly during the dry etching. Therefore, an etching selectivity pattern as shown in FIGS. 8A and 8B can be obtained, and a microlens having an accurate shape can be manufactured.

  A third means for solving the problem includes a substrate and a resist pattern having a shape corresponding to a desired shape formed on the substrate, and dry-etching the resist pattern and the substrate to A method of manufacturing a microstructure having a step of transferring a resist pattern to the substrate, wherein the height of the resist pattern exists in a region where a desired shape to be formed on the substrate is not formed at the start of the dry etching This is a method for manufacturing a fine structure characterized by being lower than the height of the resist layer.

  Similar to the first means, this means makes the resist pattern formed on the substrate an accurate shape by preventing the sudden change of the etching rate, and the first means. Has the same effect as.

  A fourth means for solving the problem includes a substrate and a resist pattern having a shape corresponding to a desired shape formed on the substrate, and dry-etching the resist pattern and the substrate to A method of manufacturing a microstructure having a step of transferring a resist pattern to the substrate, wherein a resist layer is not formed in a region where a desired shape formed on the substrate is not formed at the time of starting the dry etching. Is a method for manufacturing a fine structure.

  Similar to the second means, the means makes the resist pattern formed on the substrate an accurate shape by preventing the sudden change in the etching rate, and the second means. Has the same effect as.

  According to the present invention, the resist layer formed on the substrate is developed to form a cylindrical resist pattern, and then the resist is melted into a lens shape by heat flow, and the remaining resist and the In a manufacturing method of a microlens including a step of dry etching a substrate and transferring the shape of the resist to the substrate, a method of manufacturing a microlens having an accurate shape is provided, and the substrate and the substrate are formed In a manufacturing method of a fine structure, which has a resist pattern having a shape corresponding to a desired shape, and includes a step of dry etching the resist pattern and the substrate and transferring the resist pattern to the substrate. The manufacturing method of the microstructure which has various shapes can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Since the method of transferring the resist shape after the heat flow to the substrate is well known, in the following description, steps until the resist shape is formed by the heat flow will be described.

  FIG. 1 is a diagram for explaining a microlens manufacturing method according to a first embodiment of the present invention. As shown in FIG. 1A, a resist 2 is applied on a substrate 1 made of quartz, glass, resin or the like, and the resist 2 is exposed through a mask 3. A portion indicated by 3a in the mask is a portion corresponding to the microlens, and a small amount of light is transmitted therethrough. The portion corresponding to 3b is a portion corresponding to a portion forming between the microlenses and completely transmits light. In the present specification and claims, the portion corresponding to the microlens and the portion forming between the microlenses are referred to as a region where a resist pattern is formed, and the other region is referred to as a lens-shaped resist pattern. This is called a region where no is formed. Reference numeral 3c denotes a portion corresponding to a region where a resist pattern is not formed, and is subjected to Cr plating or the like so as to completely block light.

  When the resist is developed after exposure, a resist shape as shown in FIG. 1B is obtained. Reference numeral 2a denotes a portion that becomes a microlens. 2b is a region where a resist pattern is not formed. Since a small amount of exposure is performed on the region 2a, the height thereof is lower than the height of the region 2b where the resist pattern is not formed.

  When such a resist shape is melted by a heat flow, the shape is obtained by registering as shown in FIG. Reference numeral 4 denotes a resist having a microlens shape. Note that the height (SAG amount) of this portion is slightly higher than the height of the portion 2a described above. Reference numeral 5 denotes a resist in a region where a resist pattern is not formed. Since this portion is not exposed at all, its height is higher than the height of the resist 4 in the shape of a microlens.

  When the resist having the shape as shown in FIG. 1C and the substrate 1 are dry-etched, the lens-shaped resist pattern is still formed in a state where the microlens-shaped resist 4 is completely etched away. The resist 5 is left in a region that is not to be processed. Therefore, the dry etching is finished at this stage, and the remaining resist is removed. In this way, in the dry etching process, the resist in the region where the resist pattern is not formed remains until the end, so that the above-mentioned problem that the resist in this portion disappears and the etching selectivity changes is prevented. be able to.

  In the first embodiment of the present invention, the mask 3a of the mask 3 uses a mask that transmits a small amount of light. This portion has been conventionally known. It can be formed by using the gray scale pattern of the gray scale mask. On the other hand, by using two binary masks without using a mask having a gray scale pattern, a resist pattern having a lens shape can be used rather than a resist thickness of a portion where no lens-shaped resist pattern is formed. There is a way to lower the height.

  For example, instead of the process of FIG. 1A, the exposure process is performed in the process shown in FIGS. 9A and 9B. The process shown in FIG. 9A shows an exposure process using the binary mask 30. In the binary mask 30, the portion 3a corresponding to the microlens is formed with chrome plating that completely blocks light. The other portions 3b and 3c are the same as the mask shown in FIG.

  Next, the process shown in FIG. In this step, a binary mask 6 is used. The binary mask 6 transmits light completely in the region 3a corresponding to the portion 3a corresponding to the microlens shown in FIG. 9A and the portion 3b corresponding to the portion forming between the microlenses. However, in the same region 6c as the region 3c where the lens-shaped resist pattern is not formed, chrome plating is formed so that light is completely shielded. Using such a mask 6, exposure is performed so that the exposure amount is smaller than the exposure performed in FIG. Thereafter, when the resist is developed, a resist pattern as shown in FIG. 1B is formed. The rest is the same as in the first embodiment.

  In the modification of the first embodiment, the order of exposure with the binary mask shown in FIG. 9A and exposure with the binary mask shown in FIG. 9B may be changed. Even in this case, it is important that the exposure amount when using the binary mask shown in FIG. 9B is smaller than the exposure amount when using the binary mask shown in FIG.

  FIG. 2 is a view for explaining a microlens manufacturing method according to the second embodiment of the present invention. As shown in FIG. 2A, a resist 2 is applied on a substrate 1 made of quartz, glass, resin or the like, and the resist 2 is exposed through a mask 3. The portion indicated by 3a in the mask is a portion corresponding to the microlens and completely blocks light. The portion corresponding to 3b is a portion corresponding to a portion forming between the microlenses and completely transmits light. The portion corresponding to A is a portion corresponding to a region where the resist pattern is not formed, and completely transmits light.

  When the resist is developed after exposure, a resist shape as shown in FIG. 2B is obtained. Reference numeral 2a denotes a portion that becomes a microlens. 2b is a region where a resist pattern is not formed. In the region B where the resist pattern is not formed, the resist is completely removed.

  When such a resist shape is melted by heat flow, a resist shape as shown in FIG. 2C is obtained. Reference numeral 4 denotes a resist having a microlens shape.

  When the resist having the shape as shown in FIG. 2C and the substrate 1 are dry-etched, the resist in the region B where the lens-shaped resist pattern is not formed is not present from the beginning, and the substrate 1 is exposed. It is possible to prevent the occurrence of the above-described problem that the resists of the portions are eliminated all at once and the etching selectivity changes.

  The resist shown in FIG. 9A and the resist in the region B where the lens-shaped resist pattern is not formed using two masks that transmit light only in a portion corresponding to the region where the lens-shaped resist pattern is not formed. May be eliminated.

  The present invention is not limited to a lens, and can be applied to a method of transferring a diffraction pattern formed on a resist to a substrate. For example, in the case of a blazed diffractive optical element, even if an accurate blazed pattern is formed by a resist pattern, if the etching rate suddenly changes in the middle, the slope of the blazed pattern changes in the middle. Therefore, a blazed pattern having a desired shape cannot be formed. However, by applying the present invention, it is possible to prevent the inclination of the slope of the blaze pattern from changing in the middle and to obtain an effect that the blaze pattern can be transferred to the substrate.

  As described above, the present invention is not limited to the lens, and the present invention is an effective means when the region for forming the fine structure holiday is not the entire surface of the substrate. The “region where the desired shape formed on the substrate is not formed” as used in this specification and claims refers to the shape of a resist pattern, such as a portion where a lens-shaped resist pattern is not formed. It shows areas where transcription is not actively used.

(Example)
A positive resist was applied to a 6-inch quartz substrate having a thickness of 1.2 mm so as to have a thickness of 7 μm. Then, the prebaking process was performed for 30 minutes at 90 degreeC. Subsequently, exposure was performed with an i-line stepper using a simple chrome light-shielding binary mask. The exposure area for manufacturing the microlens array was (60 × 60) mm, and the entire outer surface was overexposed and developed.

  As a result, a resist cylindrical shape having a pitch of 110 μm and a diameter of 100 μm was manufactured in a region of (60 × 60) mm. The outside is a state in which there is no resist and the surface of the optical substrate is exposed.

  This was heated at a temperature of 150 to 160 ° C. for 30 minutes, and a resist microlens was manufactured by heat flow. The manufactured resist shape was as shown in FIG.

  The resist microlens array was transferred to a quartz substrate with an RIE dry etching apparatus. The gas flow rate setting during dry etching was fixed. FIG. 4 shows a lens shape after dry etching, and FIG. 5 shows a selectivity ratio profile during etching. The change in the selection ratio was constant, and the shape accuracy of the obtained quartz microlens was good.

(Comparative example)
A positive resist was applied to a 6-inch quartz substrate having a thickness of 1.2 mm so as to have a thickness of 7 μm. Then, the prebaking process for 30 minutes was performed at 90 degreeC. Using a simple chrome light shielding binary mask, exposure was performed with an i-line stepper. The exposure area for manufacturing the microlens array is (60 * 60) mm.

  As a result, a resist cylindrical shape having a pitch of 110 μm and a diameter of 100 μm was manufactured in a region of (60 * 60) mm. The outside is a state in which the remaining resist coating 7 μm remains on the entire surface.

  This was heated at a temperature of 150 to 160 ° C. for 30 minutes, and a resist microlens was manufactured by heat flow. The manufactured resist shape was almost the same as the shape shown in FIG.

  The resist microlens array was transferred to a quartz substrate with an RIE dry etching apparatus.

  The gas flow rate setting during dry etching was fixed. FIG. 6 shows the lens shape after dry etching, and FIG. 7 shows the selectivity ratio profile during etching. It can be seen that the change in the selection ratio in the radial direction of the microlens is not constant, and the selection ratio changes in the middle. As a result, it was found that the shape accuracy of the quartz microlens was also deteriorated.

It is a figure for demonstrating the manufacturing method of the micro lens which is the 1st Embodiment of this invention. It is a figure for demonstrating the manufacturing method of the micro lens which is the 2nd Embodiment of this invention. It is a graph which shows the resist shape of a lens shape manufactured in the Example of this invention, and a shape error. It is a graph which shows the lens shape and shape error which were obtained by the Example of this invention. It is a figure which shows the selection ratio profile at the time of the etching in the Example of this invention. It is a graph which shows the lens shape and shape error which were obtained by the comparative example of this invention. It is a figure which shows the selectivity ratio profile at the time of the etching in the comparative example of this invention. It is a figure which shows the example of the pattern of the etching selectivity of the radial direction of a micro lens. It is a figure for demonstrating the manufacturing method of the micro lens which is a modification of the 1st Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Board | substrate, 2 ... Resist, 2a ... Resist of the part used as a micro lens, 2b ... Resist of the part used as the area | region in which a lens-shaped resist pattern is not formed, 3 ... Mask, 3a ... Part corresponding to a micro lens 3b: a part corresponding to a part forming between the microlenses of the mask, a part corresponding to a part forming between the microlenses, 3c: a part corresponding to an area where the resist pattern of the mask is not formed, 4 ... of the microlens Shaped resist, 5... Resist in a region where a resist pattern is not formed, 6... Mask, 6 a... Region 3 a corresponding to the microlens and region 3 b corresponding to the portion forming between the microlenses, 6 b. The same region as the region 3c where the lens-shaped resist pattern is not formed

Claims (4)

  The resist layer formed on the substrate is developed to form a cylindrical resist pattern, and then the resist is melted by heat flow into a lens shape, and the remaining resist and the substrate are dry etched. A method of manufacturing a microlens including a step of transferring the shape of the resist onto the substrate, and at the start of the dry etching, the height of the lens-shaped resist formed by heat flow (SAG amount) is: A method of manufacturing a microlens, wherein the height of a resist layer existing in an area where the lens-shaped resist pattern is not formed is lower.   The resist layer formed on the substrate is developed to form a cylindrical resist pattern, and then the resist is melted by heat flow into a lens shape, and the remaining resist and the substrate are dry etched. A method of manufacturing a microlens including a step of transferring the shape of the resist to the substrate, wherein a resist layer is not formed in a region where the lens-shaped resist pattern is not formed at the start of the dry etching. A method of manufacturing a microlens.   A microstructure having a substrate and a resist pattern having a shape corresponding to a desired shape to be formed on the substrate, and a step of dry etching the resist pattern and the substrate to transfer the resist pattern to the substrate In the manufacturing method of the body, at the time of starting the dry etching, the height of the resist pattern is lower than the height of the resist layer existing in a region where a desired shape formed on the substrate is not formed. The manufacturing method of the fine structure characterized by this.   A microstructure having a substrate and a resist pattern having a shape corresponding to a desired shape to be formed on the substrate, and a step of dry etching the resist pattern and the substrate to transfer the resist pattern to the substrate A method for manufacturing a fine structure, characterized in that a resist layer is not formed in a region where a desired shape formed on the substrate is not formed at the start of the dry etching.

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