JP2006047612A - Method for designing gray scale mask, method for manufacturing gray scale mask and method for manufacturing optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for designing a gray scale mask for accurately forming an optical element having a desired shape. <P>SOLUTION: The method includes: unit area determining steps S1, S2 to determine a unit area on a resist to be irradiated with light having predetermined intensity corresponding to a desired resist shape and to determine a unit area on a gray scale mask having predetermined transmittance corresponding to the unit area on the resist; resist sensitivity curve determining steps S3 to S5 to determine a resist sensitivity curve which shows the relation between the transmittance of a gray scale mask and a groove depth formed in a resist when a gray scale mask with varied transmittance by unit areas on the gray scale mask is used; and a transmittance distribution determining step S6 to obtain the transmittance in each unit area on the gray scale mask by using the resist sensitivity curve and to determine the distribution of transmittance of the gray scale mask corresponding to the desired resist shape. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a gray scale mask designing method, a gray scale mask manufacturing method, and an optical element manufacturing method, and in particular, a gray scale mask designing method for manufacturing an optical element having a three-dimensional microstructure such as a microlens element. The present invention relates to a method of manufacturing a gray scale mask designed by the design method and a technique of a method of manufacturing an optical element using the gray scale mask manufactured by the manufacturing method.

  Conventionally, a photolithography technique is used in the manufacture of an optical element having a three-dimensional microstructure. Photolithography is a technique in which a resist, which is a photoreactive photosensitive material, is applied to a substrate, exposed, and developed to form a pattern on the resist. The resist pattern can be formed on the substrate by performing etching after forming the pattern on the resist. As a method of forming a desired pattern on the resist, for example, a technique of exposing the resist through a gray scale mask having a change in light transmittance is used. The gray scale mask obtains gradation by changing the light transmittance. As a technique for designing a gray scale mask, for example, there is one proposed in Patent Document 1.

JP 2001-147515 A

  The technique of Patent Document 1 determines the light transmittance distribution of a gray scale mask using a resist sensitivity curve indicating the relationship between the exposure amount of a resist and the depth of a groove formed in the resist. When the resist sensitivity curve is used, the exposure amount of the resist for each unit area is obtained from the depth of the groove formed for each unit area on the resist. The gray scale mask is designed by determining the light transmittance distribution corresponding to the exposure amount of the resist for each unit area. However, if the unit area is set after the resist sensitivity curve is determined in advance, a resist pattern having a shape different from the target shape may be formed. For example, since the optical element to be manufactured is minute, when the unit area on the gray scale mask is minute, a shape shift is likely to occur. Furthermore, the shape of the resist pattern may change due to thermal expansion of the glass serving as the base material of the gray scale mask. If a resist pattern having a shape different from the design is formed, it is difficult to accurately manufacture the optical element, which is a problem.

  The present invention has been made in view of the above problems, and a gray scale mask design method for accurately forming an optical element having a desired shape, a gray scale mask manufacturing method designed by the design method, It is another object of the present invention to provide a method for manufacturing an optical element using a gray scale mask manufactured by the manufacturing method.

  In order to solve the above-described problems and achieve the object, according to the present invention, a unit area on a resist to be irradiated with light of a predetermined intensity is determined according to a desired resist shape, and a unit on the resist is determined. A unit area determining step for determining a unit area on the gray scale mask having a predetermined light transmittance corresponding to the area, and a light transmittance for each unit area on the gray scale mask determined in the unit area determining step. A resist sensitivity curve determining step for determining a resist sensitivity curve indicating a relationship between the light transmittance of the gray scale mask and the depth of the groove formed in the resist when using the changed gray scale mask, and determining the resist sensitivity curve Using the resist sensitivity curve obtained in the process, the light transmittance per unit area on the gray scale mask is obtained, and the gray scale corresponding to the desired resist shape is obtained. It is possible to provide a method for designing a gray scale mask which comprises a light transmissivity distribution determining step of determining a distribution of light transmittance scale mask, a.

  In the gray scale mask designing method of the present invention, first, a unit area on the gray scale mask is determined. After determining the unit area, a resist sensitivity curve is determined using a gray scale mask in which the light transmittance is changed for each unit area. By determining the unit area on the gray scale mask corresponding to the unit area on the resist, a resist sensitivity curve capable of accurately corresponding to the target resist shape is obtained. Thus, by obtaining a resist sensitivity curve that can accurately correspond to a target resist shape, a resist shape that accurately reproduces the desired resist shape can be formed. By using a gray scale mask capable of accurately forming a resist shape, an optical element having a desired shape can be accurately formed. Thus, a gray scale mask for accurately forming an optical element having a desired shape can be designed.

  According to a preferred aspect of the present invention, it is desirable that the unit area on the gray scale mask is larger than the unit area on the resist. The optical element can be densely formed as the unit area on the resist is reduced. In order to reduce the unit area on the resist, for example, it is conceivable to reduce the unit area on the gray scale mask. If the unit area on the gray scale mask is reduced, processing that is faithful to the design is possible, but manufacturing of the gray scale mask becomes very difficult. By making the unit area on the gray scale mask larger than the unit area on the resist, a gray scale mask with high resolution can be easily manufactured. In this case, for example, by reducing the light transmitted through the gray scale mask and irradiating the resist, the unit area on the gray scale mask corresponds to the unit area on the resist, and the resist can be processed accurately. Furthermore, even when thermal expansion occurs in the glass serving as the base material of the gray scale mask, it is possible to reduce the influence thereof. Thereby, an optical element having a desired shape can be accurately formed, and a gray scale mask can be easily manufactured.

  Furthermore, according to the present invention, a unit area on the resist to be irradiated with light having a predetermined intensity is determined corresponding to a desired resist shape, and a predetermined light transmittance is set corresponding to the unit area on the resist. When using a unit area determining step for determining a unit area on the gray scale mask to be held, and a gray scale mask in which the light transmittance is changed for each unit area on the gray scale mask determined in the unit area determining step, A resist sensitivity curve determination process for determining a resist sensitivity curve indicating the relationship between the light transmittance of the scale mask and the depth of the groove formed in the resist, and a gray scale using the resist sensitivity curve obtained in the resist sensitivity curve determination process. Obtain the light transmittance of each unit area on the mask and determine the light transmittance distribution of the gray scale mask corresponding to the desired resist shape. And a gray scale mask forming step for forming a gray scale mask having a light transmittance of the distribution determined in the light transmittance distribution determining step. A manufacturing method can be provided. By designing a gray scale mask by the above design method, a gray scale mask for accurately forming an optical element having a desired shape can be manufactured.

  Furthermore, according to the present invention, a unit area on the resist to be irradiated with light having a predetermined intensity is determined corresponding to a desired resist shape, and a predetermined light transmittance is set corresponding to the unit area on the resist. When using a unit area determining step for determining a unit area on the gray scale mask to be held, and a gray scale mask in which the light transmittance is changed for each unit area on the gray scale mask determined in the unit area determining step, A resist sensitivity curve determination process for determining a resist sensitivity curve indicating the relationship between the light transmittance of the scale mask and the depth of the groove formed in the resist, and a gray scale using the resist sensitivity curve obtained in the resist sensitivity curve determination process. Obtain the light transmittance of each unit area on the mask and determine the light transmittance distribution of the gray scale mask corresponding to the desired resist shape. A light transmittance distribution determining step, a gray scale mask forming step for forming a gray scale mask having a light transmittance of the distribution determined in the light transmittance distribution determining step, and a resist layer forming for forming a resist layer on the substrate And a resist shape forming step of forming a resist shape on the resist layer by exposing and developing the resist layer through the grayscale mask formed in the grayscale mask forming step. An element manufacturing method can be provided. Since the gray scale mask manufactured by the above manufacturing method is used, an optical element having a desired shape can be accurately formed.

  Moreover, as a preferable aspect of the present invention, it is desirable to include a resist shape transfer step of transferring the resist shape obtained in the resist shape forming step to the substrate. Moreover, as a preferable aspect of the present invention, it is desirable to include a mold transfer process in which the resist shape obtained in the resist shape forming process is transferred to a mold, and the mold shape is transferred to another member. An optical element can be formed by transferring the resist shape to a substrate or another member.

  In a preferred embodiment of the present invention, the unit area on the gray scale mask is larger than the unit area on the photoresist, and the resist layer is irradiated with the light transmitted through the gray scale mask reduced in the resist shape forming step. It is desirable. By making the unit area on the gray scale mask larger than the unit area on the resist, a gray scale mask with high resolution can be easily manufactured. Further, by reducing the light transmitted through the gray scale mask and irradiating the resist, the unit area on the gray scale mask corresponds to the unit area on the resist, and the resist can be processed accurately. Furthermore, even when thermal expansion occurs in the glass member serving as the base material of the gray scale mask, it is possible to reduce the influence thereof. Thereby, an optical element having a desired shape can be accurately formed, and the cost can be further reduced.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a flowchart showing a manufacturing procedure of a gray scale mask in an optical element manufacturing method according to an embodiment of the present invention. In this example, a manufacturing method of a microlens array which is an optical element will be described. The manufacturing procedure of the microlens array can be divided into a step of designing a gray scale mask, a step of manufacturing the designed gray scale mask, and a step of manufacturing the micro lens array using the manufactured gray scale mask.

  In the flowchart shown in FIG. 1, steps S1 to S6 are steps for designing a gray scale mask. Steps S1 and S2 are unit area determination steps. In step S1, the operator determines a unit area on the resist to be irradiated with light having a predetermined intensity corresponding to a desired resist shape. The unit area on the resist can be appropriately determined according to the size of the microlens element so that a desired microlens element shape can be formed.

  Next, in step S2, a unit area on the gray scale mask having a predetermined light transmittance is determined corresponding to the unit area on the resist. In this embodiment, as will be described later, the resist is exposed using a reduction exposure apparatus. The light transmitted through the unit area on the gray scale mask is set to be reduced and irradiated onto the unit area on the resist. Therefore, the unit area on the gray scale mask needs to be larger than the unit area on the resist in consideration of the reduction magnification by the reduction exposure apparatus.

  Steps S3 to S5 are resist sensitivity curve determination steps. Step S3 is a trial processing step in which the resist is exposed and developed using the gray scale mask in which the light transmittance is changed for each unit area on the gray scale mask determined in step S2. As the resist, a positive photoresist in which the exposed portion can be removed by development can be used. Next, in step S4, the depth of the groove (resist depth) formed in the resist is measured using a laser microscope, an atomic force microscope, or an interference optical measuring instrument. In step S5, a resist sensitivity curve is determined from the relationship between the light transmittance of the gray scale mask and the groove depth measured in step S4.

  After determining the resist sensitivity curve, in step S6, the light transmittance for each unit area on the gray scale mask is obtained using the resist sensitivity curve, and the light transmittance distribution of the gray scale mask corresponding to the desired resist shape is obtained. decide. The gray scale mask is designed by steps S1 to S6. In step S7, a gray scale mask is formed according to the design in steps S1 to S6. In this way, the gray scale mask manufacturing process is completed.

  Here, a gray scale mask design method will be described in more detail with reference to FIGS. FIG. 2 illustrates a unit area on the gray scale mask. For example, in the case of forming a 16 μm square microlens element, it is assumed that the unit area on the resist is determined to be 1 μm square. In addition, a reduction exposure apparatus used for resist exposure uses a stepper that reduces the incident light to 1/5 and emits it. The unit area portion 21 on the gray scale mask has one side d1 of 5 μm. In the gray scale mask, the unit area portion 21 having a side d1 of 5 μm corresponds to a unit area of 1 μm square on the resist by reduced exposure. In the gray scale mask, ten unit area portions 21 are arranged in a line.

  The light transmittance of each unit area portion 21 is changed in increments of 6.9% from the maximum of 75.0% to the minimum of 13.0%. When such a gray scale mask is used, resist processing can be performed with a resolution of 6.9%. Further, as a comparison with the gray scale mask having the unit area portion 21 of 5 μm square, the gray scale mask having the unit area portion 22 having the side d2 of 100 μm will be described. A gray scale mask having a unit area portion 22 having a side d2 of 100 μm is an example of a gray scale mask in which the unit area on the gray scale mask and the unit area on the resist do not correspond at all. The unit area portion 22 having a side d2 of 100 μm in the gray scale mask corresponds to a unit area of 20 μm square on the resist by reduction exposure.

  FIG. 3 is an explanatory diagram of reduced exposure by the stepper 30. Light L from a light source such as a lamp enters the gray scale mask GSM substantially uniformly. The light transmitted through the gray scale mask GSM is reduced to about one fifth by the stepper 30. As the stepper 30, for example, a projection lens that projects incident light with a reduced size can be used. The fact that the light is reduced to about 1/5 means that the range D1 in which the light beam of the incident light of the stepper 30 exists in a plane substantially perpendicular to the optical axis becomes the range D2 of about 1/5. The light transmitted through the stepper 30 enters the resist 32 on the workpiece.

  FIG. 4 shows a resist sensitivity curve determined from the relationship between the light transmittance of the gray scale mask GSM and the depth of the groove formed in the resist 32 when the resist 32 is trial processed. A curve with A is a resist sensitivity curve when a gray scale mask GSM having a unit area portion 21 of 5 μm square is used. A curve with B is a resist sensitivity curve when a gray scale mask GSM having a unit area portion 22 of 100 μm square is used. In the graph shown in FIG. 4, the vertical axis represents the depth of the groove formed in the resist 32, and the horizontal axis represents the light transmittance of the gray scale mask GSM. Note that the resist depth on the vertical axis in FIG. 4 indicates the position of the bottom of the groove when the depth position when the light transmittance is maximum is 0 (zero) μm.

  The data shown in FIG. 4 is obtained when AZP-4620 manufactured by Clariant Japan is used as the resist 32 and exposed at 1500 mJ. Further, the data of the groove depth of the resist 32 is obtained by measuring with a laser microscope. Further, the gray scale mask GSM is manufactured using HEBS (High electron beam sensitive) glass as a base material.

  Comparing both graphs A and B, it can be seen that the resist 32 is processed in the same manner in the portion where the light transmittance is large. On the other hand, there is a difference in the depth of the groove formed in the resist 32 in the portion where the light transmittance is small. For example, in a portion where the light transmittance is 13%, there is a difference of about 1 μm between the case where the unit area of the gray scale mask GSM is 5 μm and the case where the unit area is 100 μm.

  For example, when the resist sensitivity curve is determined using a gray scale mask GSM having a unit area of 100 μm square, an error occurs even if the gray scale mask is designed with the unit area on the resist being 1 μm square. Such errors affect the shape of the manufactured microlens array. This indicates that in order to manufacture an optical element having a desired shape, the unit area on the gray scale mask when obtaining the resist sensitivity curve needs to correspond to the unit area on the resist. By associating the unit area on the gray scale mask with the unit area on the resist, a resist sensitivity curve that can accurately correspond to the target resist shape can be obtained. Thus, a gray scale mask for accurately forming an optical element having a desired shape can be designed.

Here, the HEBS glass will be described. The HEBS glass has an Ag alkali halide dope layer formed on the surface. The Ag alkali halide doped layer can be obtained by forming a doped layer of Ag ⁺ ions in a portion having a thickness of about 3 μm on the glass surface by Ag ⁺ ion exchange reaction. When the electron beam is irradiated to the doped layer formed substantially uniformly on the glass surface, Ag ⁺ ions obtained from electrons are changed to Ag. Since Ag has the property of absorbing ultraviolet rays, the gray scale with different amounts of transmission of ultraviolet rays can be obtained by changing the irradiation amount of electron beam, acceleration voltage of electron beam, beam current, and beam diameter for each irradiation position. A mask is formed.

The light transmittance of the gray scale mask is expressed as a percentage, as well as an OD value OD value represented by the following formula = −log ₁₀ {light transmittance (%) / 100}.
Can also be represented by Generally, the OD value of a gray scale mask is about 0.15 to 2.0. In addition, when a gray scale mask is used, gradation can be obtained with a minimum gradation width of about 0.0092 and a maximum number of gradations of about 200.

  5-7 is explanatory drawing of the process which determines light transmittance distribution. For example, consider a case where a resist structure 52 having the resist shape 51 shown in FIG. 5 is manufactured. The diagram shown at the top of FIG. 5 is a cross-sectional view taken along the line P-P ′ of the resist structure 52. The distribution of the depth of the groove formed in the resist to obtain the resist structure 52 is determined according to the shape of the desired microlens element.

  Next, the distribution of light transmittance of the gray scale mask GSM for forming the resist structure 52 having the shape shown in FIG. 5 is determined using the resist sensitivity curve. The light transmittance of the gray scale mask GSM is determined for each unit area portion 21 of 5 μm square as shown in FIG. If a microlens element having a symmetrical shape in the vertical and horizontal directions is manufactured, as shown in FIG. 6, the light transmittance may be determined for, for example, a part on the upper right side of a 40 μm square. FIG. 7 shows an example of the light transmittance determined in the light transmittance distribution determining step. The gray scale mask GSM can be designed as described above. When the gray scale mask GSM manufactured based on the data of FIG. 7 is used, a resist structure 52 having a unit area of 1 μm square and a side of 16 μm can be formed.

  The microlens element can be formed densely as the unit area on the resist is reduced. When the unit area on the resist is reduced, it is considered that the unit area on the gray scale mask may be simply reduced. However, if the unit area on the gray scale mask is reduced, it is very difficult to manufacture the gray scale mask GSM. In this embodiment, the resist 32 is subjected to reduced exposure using the stepper 30, so that the resist 32 can be precisely processed even if a gray scale mask GSM having a unit area larger than the unit area on the resist is used.

  By making the unit area on the gray scale mask larger than the unit area on the resist, the production of the gray scale mask GSM can be facilitated, and the gray scale mask GSM can have high resolution. In this case, for example, by reducing the light transmitted through the gray scale mask and irradiating the resist, the unit area on the gray scale mask corresponds to the unit area on the resist, and the resist can be processed accurately.

  FIG. 8 shows the amount of thermal expansion of HEBS glass used for the gray scale mask GSM. The numerical values in the column labeled HEBS (1/1) in the table indicate the amount of expansion of the HEBS glass of 100 mm at each temperature with 0 ° C. as a reference. The HEBS glass has a property that the amount of expansion with respect to heat is larger than that of quartz glass, Pyrex (registered trademark), or the like. When the HEBS glass expands due to heat, the area of the drawing region on the gray scale mask GSM changes. When the area of the drawing region on the gray scale mask GSM changes, a resist pattern having a shape different from the design may be formed.

  The numerical values in the column indicated as HEBS (1/5) in the table are obtained by converting the amount of expansion of the HEBS glass to 1/5. When reducing exposure is performed using the stepper 30, there is also an effect of reducing the influence due to thermal expansion of the HEBS glass. As described above, according to the present invention, it is possible to obtain a gray scale mask GSM which is easy to manufacture, has high resolution, and can accurately form an optical element having a desired shape.

  9A and 9B show a procedure for manufacturing a microlens array as an optical element using the gray scale mask manufactured according to the procedure shown in FIG. As shown in step a of FIG. 9A, a resist layer 902 is first formed on a substrate 901 in a resist layer forming step. The resist layer 902 is formed by applying a resist material on the substrate 901 and further pre-baking.

  Next, as shown in step b, the resist layer 902 is exposed through the gray scale mask 903 formed in the gray scale mask forming step. The resist layer 902 is exposed by reducing the light transmitted through the gray scale mask 903 to about one fifth by the stepper 30 as in the case of obtaining the resist sensitivity curve. In this manner, a shape corresponding to the transmittance distribution of the gray scale mask 903 is transferred to the resist layer 902. The type of resist material and the exposure conditions are the same as in the case of trial processing when determining the resist sensitivity curve. The resist type, exposure conditions, and the like may be the same as those for obtaining the resist sensitivity curve, and are not limited to the above conditions.

  In step c, the resist layer 902 after exposure is developed with a developer, so that, for example, a resist shape 904 having a curved surface is formed on the resist layer 902. Steps b and c are resist layer processing steps for processing the resist layer 902 by exposure and development. The developed resist layer 902 is further cured by post-baking. In addition, the post-baking can cause sagging on the surface of the resist layer 902, and the surface of the resist shape 904 can be smoothed.

  Next, in the resist shape transfer step shown in step d, the resist shape 904 of the resist layer 902 is transferred to the substrate 901. By transferring the resist shape 904 to the substrate 901, a microlens shape 905 that is substantially the same as the resist shape 904 is formed on the substrate 901. The resist shape 904 is transferred by etching. Etching is performed by dry etching or a combination of dry etching and wet etching.

Dry etching can be performed by, for example, the RIE method. As the etching gas, a mixed gas of oxygen and a fluorinated gas such as C ₄ F ₈ or CF ₄ is used. Thereby, the uneven | corrugated shape of the process surface resulting from an etching spot can be reduced, and a smooth and favorable prism element can be manufactured. Further, by controlling the etching conditions such as the etching gas concentration, the mixing ratio, the etching gas pressure, the magnetic field strength, and the etching time, the selection ratio for transferring the resist shape 904 to the substrate 901 is approximately 0.7 to 1.8 times. Can be controlled by range. In addition, irregularities of about several tens to several hundreds of nanometers that cause unnecessary scattered light may occur on the surface of the prism element formed by dry etching. For this reason, by performing wet etching with a hydrofluoric acid solution after dry etching, the uneven shape of the processed surface is smoothed, and unnecessary scattered light can be reduced.

  Finally, as shown in step e of FIG. 9B, a microlens array having a plurality of microlens elements is formed by forming a transparent resin layer 906 on a substrate 901 on which a microlens shape 905 is formed. Is done. Furthermore, the microlens array may be formed by a mold transfer process shown in steps f to h. First, as shown in step f, the resist shape 904 obtained in step c is subjected to electroless Ni plating to manufacture a mold 907. Thereby, the resist shape 904 is transferred to the mold 907. Next, the replica 908 shown in the step h is created by transferring the shape of the mold 907 to another member 908 in the step g. As a result, a large number of replicas 908 can be easily manufactured. Similarly to step e, a microlens array is formed by forming a transparent resin layer on the replica 908 obtained in step h.

  FIG. 10 shows a comparison between the resist shape 904 formed according to this embodiment and the designed resist shape. In the graph shown in FIG. 10, the vertical axis represents the resist depth, and the horizontal axis represents the position on the resist when the center position of the resist shape is used as a reference. The curve with C indicates the distribution of the resist depth of the resist shape 904 formed in this example. The curve with E indicates the resist depth distribution of the designed resist shape.

  From the graph, it can be seen that a resist shape 904 accurately formed in a desired resist shape can be obtained by using the gray scale mask 903 designed by the design method of this embodiment. In the resist shape obtained by the present invention, the error from the design value can be reduced to such an extent that the influence on the optical characteristics of the microlens array can be reduced, for example, within about 7%. Thereby, the effect that the optical element of a desired shape can be formed accurately is obtained. The manufacturing method of the present embodiment is applied not only to a microlens array but also to other optical elements such as a microlens prism array, a spatial light modulation element for modulating light according to an image signal, a communication device, and a medical device. be able to.

  As described above, the grayscale mask designing method according to the present invention is suitable for manufacturing a minute optical element.

The flowchart which shows the manufacture procedure of a gray scale mask. Explanatory drawing of the unit area on a gray scale mask. Explanatory drawing of the reduction exposure by a stepper. Explanatory drawing of a resist sensitivity curve. Explanatory drawing of the process which determines distribution of the light transmittance of a gray scale mask. Explanatory drawing of the process which determines distribution of the light transmittance of a gray scale mask. The figure which shows the example of the light transmittance distribution of a gray scale mask. The figure explaining the amount of thermal expansion of HEBS glass. Explanatory drawing of the manufacturing procedure of a micro lens array. Explanatory drawing of the manufacturing procedure of a micro lens array. Explanatory drawing of the resist shape manufactured by the present Example.

Explanation of symbols

  21, 22 Unit area on gray scale mask, 30 stepper, 32 resist, GSM gray scale mask, 51 resist shape, 52 resist structure, 901 substrate, 902 resist layer, 903 gray scale mask, 904 resist shape, 905 micro Lens shape, 906 transparent resin layer, 907 mold, 908 replica

Claims (7)

A unit area on the resist to be irradiated with light of a predetermined intensity is determined in accordance with a desired resist shape, and a gray scale mask having a predetermined light transmittance corresponding to the unit area on the resist is determined. A unit area determining step for determining a unit area;
When using the gray scale mask in which the light transmittance is changed for each unit area on the gray scale mask determined in the unit area determining step, the light transmittance of the gray scale mask is formed on the resist. A resist sensitivity curve determining step for determining a resist sensitivity curve indicating a relationship with a depth of a groove to be formed;
Using the resist sensitivity curve obtained in the resist sensitivity curve determination step, the light transmittance for each unit area on the gray scale mask is obtained, and the light transmittance of the gray scale mask corresponding to the desired resist shape A light transmittance distribution determining step for determining the distribution of
A method for designing a gray scale mask, comprising:   2. The method of designing a gray scale mask according to claim 1, wherein a unit area on the gray scale mask is larger than a unit area on the resist. A unit area on the resist to be irradiated with light of a predetermined intensity is determined in accordance with a desired resist shape, and a gray scale mask having a predetermined light transmittance corresponding to the unit area on the resist is determined. A unit area determining step for determining a unit area;
When using the gray scale mask in which the light transmittance is changed for each unit area on the gray scale mask determined in the unit area determining step, the light transmittance of the gray scale mask is formed on the resist. A resist sensitivity curve determining step for determining a resist sensitivity curve indicating a relationship with a depth of a groove to be formed;
Using the resist sensitivity curve obtained in the resist sensitivity curve determination step, the light transmittance for each unit area on the gray scale mask is obtained, and the light transmittance of the gray scale mask corresponding to the desired resist shape The light transmittance distribution determining step for determining the distribution of
A gray scale mask forming step of forming the gray scale mask having the light transmittance of the distribution determined in the light transmittance distribution determining step;
A method for producing a gray scale mask, comprising: A unit area on the resist to be irradiated with light having a predetermined intensity is determined in accordance with a desired resist shape, and on a gray scale mask having a predetermined light transmittance corresponding to the unit area on the resist. A unit area determining step for determining a unit area;
When using the gray scale mask in which the light transmittance is changed for each unit area on the gray scale mask determined in the unit area determining step, the light transmittance of the gray scale mask is formed on the resist. A resist sensitivity curve determining step for determining a resist sensitivity curve indicating a relationship with a depth of a groove to be formed;
Using the resist sensitivity curve obtained in the resist sensitivity curve determination step, the light transmittance for each unit area on the gray scale mask is obtained, and the light transmittance of the gray scale mask corresponding to the desired resist shape The light transmittance distribution determining step for determining the distribution of
A gray scale mask forming step of forming the gray scale mask having the light transmittance of the distribution determined in the light transmittance distribution determining step;
A resist layer forming step of forming a resist layer on the substrate;
A resist shape forming step of forming the resist shape on the resist layer by exposing and developing the resist layer through the grayscale mask formed in the grayscale mask forming step;
The manufacturing method of the optical element characterized by the above-mentioned.   5. The method of manufacturing an optical element according to claim 4, further comprising a resist shape transfer step of transferring the resist shape obtained in the resist shape forming step to the substrate.   5. The optical element according to claim 4, further comprising a mold transfer step of transferring the resist shape obtained in the resist shape forming step to a mold and transferring the shape of the mold to another member. Manufacturing method. A unit area on the gray scale mask is larger than a unit area on the photoresist;
The optical element manufacturing method according to claim 4, wherein, in the resist shape forming step, the light transmitted through the gray scale mask is reduced and irradiated to the resist layer.

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