JP2007193243A - Exposure mask, exposure method, method for manufacturing exposure mask, three-dimensional device, and method for manufacturing three-dimensional device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To produce an optical device having a large area by stitch exposure with a reduced error in exposure dose on a stitch in the process of forming a three-dimensional structure by using a gray tone pattern. <P>SOLUTION: An exposure mask M to be used for an exposure device includes a unit pattern (t) where a plurality of pattern blocks each comprising a pair of a light-shielding pattern which blocks illumination light exiting from the exposure device and a transmitting pattern which transmits the illumination light are continuously disposed with the pitches of the continuous pattern blocks being constant while the ratio of the light-shielding pattern to the transmitting pattern gradually varied; and an array pattern (s) comprising the unit patterns (t) disposed in a matrix. The mask is set in such a manner that the total exposure dose on a unit pattern in the outermost circumference of the array pattern (s) after exposing a plurality of times is almost equal to the exposure dose on a unit pattern not included in the outermost circumference after single exposure. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an exposure mask for forming a device having a three-dimensional shape such as an optical lens array by photolithography, an exposure mask manufacturing method, an exposure method, a three-dimensional device, and a three-dimensional device manufacturing method. .

  Semiconductors, liquid crystals are one of the methods for manufacturing 3D devices such as micro optical components such as microlens arrays used in video device application products such as CCD (Charge Coupled Device) and LCD (Liquid Crystal Display). There is a method of applying a photolithography technique used in device manufacturing or the like.

  That is, as shown in FIG. 11, by giving a desired exposure amount distribution to the photoresist, which is a photosensitive material, the photoresist is three-dimensionally processed and etched using the photoresist as a mask, so that silicon, a glass substrate, etc. An optical device such as a microlens is produced by processing three-dimensionally and then spin-coating a high refractive index resin or the like.

  The photomask used in this lithography process is realized by multiple exposure using a plurality of masks as shown in FIG. An exposure method using this technique will be described in one dimension with reference to FIG. The final exposure dose distribution is D (X) in FIG.

  First, the exposure amount E [1] is given to the region <1> with the mask (1) in FIG. Next, the exposure amount E [2] is given to the region <2> with the mask (2). At this time, the total exposure amount D1 of the region <1> is E [1] + E [2]. Further, the mask (3), the mask (4),..., The mask (n) (not shown) are sequentially exposed with the exposure amounts E [3], E [4],. The final exposure dose D [i] is D [i] = E [i] + E [i + 1] +... + E [n], and a desired discrete exposure dose distribution is obtained. In this case, the number n of masks corresponds to the exposure position resolution. For example, when n = 10, an exposure step of 10 gradations is obtained.

  Recently, in addition to the multiple exposure method using a plurality of masks, a single exposure using a so-called gray-tone mask having a continuous distribution in the transmittance of the light shielding film as shown in Patent Document 1 can be performed. A method for obtaining a desired exposure dose distribution has also been developed. This conceptual diagram is shown in FIG.

  In the above-described two methods, the former technique based on multiple mask multiple exposure is multiple multiple exposure and multistage exposure in terms of time, so that a stepped shape remains in the obtained integrated exposure amount distribution. Further, the number of exposure gradations to be obtained is the number of masks, that is, the number of exposures, and there is a problem that a practically sufficient number of gradations cannot be obtained because it is about 10 steps. Moreover, the complexity of the exposure process and the mask cost proportional to the number of masks occur, and various problems arise.

  Although the one-time exposure method using the latter gray-tone mask can obtain an almost continuous exposure amount distribution, it is generally very difficult to create such a gray-tone mask, and a special film material, Since a special film forming technique is required, the mask cost becomes very high. Further, the special film material is worried about change with time with respect to heat, and there is also a concern about performance stability (thermal stability) during use.

  As a measure for solving these problems, the inventors of the present invention configure a mask with a binary mask pattern having a resolution limit pitch or less as shown in FIG. 14, and spatially set the opening size or the dot remaining pattern size. A technology that enables an arbitrary three-dimensional structure formation by changing is proposed (Japanese Patent Application No. 2004-00762).

  In designing such a mask, the 0th-order light intensity of a single two-dimensional array pattern having a certain pitch and a certain opening size is theoretically calculated, and based on this, the opening size for obtaining a predetermined light amount at a predetermined position is determined. A design technique is adopted in which the opening size is changed depending on the location so that a desired resist residual film thickness can be obtained at a predetermined position.

JP 2002-189280 A

  By the way, an actual microlens array, which is an example of a three-dimensional device, may require an array whose array size is larger than the exposure field size of an exposure machine depending on the number of arrays required as a device and the size of a single lens. There are many. In such a case, it is necessary to increase the area by so-called connection exposure or stitch exposure in which exposure shots are connected and arranged.

  However, as a problem of stitch exposure, discontinuity of exposure amount, that is, exposure amount error occurs at the adjacent exposure shot connection part, and an error occurs in the resist shape after development, and dry etching is performed using the resist as a mask. When the glass substrate is processed by the above method, or when a mold is formed on the resist structure after development by an electroless plating method and a resin or the like is used as a final optical device by a stamping method, there is a problem that the joint can be visually observed. Further, the gray tone mask method has a problem that the upper limit of the entire lens array size to be formed is substantially limited by the exposure field size of the exposure apparatus.

  For this reason, when forming an optical device where the overall lens array size required is greater than the exposure field size, a stamping method using a large mold created by mechanical processing, or another method such as the multiple exposure method described above I have to make it. In this case, the former has a problem of mold cost, and the latter has an increase in the number of process steps.

  The present invention has been made to solve such problems. That is, according to the present invention, in an exposure mask used in an exposure apparatus, a plurality of pattern blocks each composed of a pair of a light shielding pattern that blocks illumination light emitted from the exposure apparatus and a transmission pattern that transmits illumination light are consecutive. A unit pattern that is arranged so that the ratio between the light shielding pattern and the transmission pattern is gradually changed and the unit pattern is arranged in a matrix. The total exposure amount when the unit pattern that is the outermost periphery of the array pattern is exposed a plurality of times is substantially equal to the exposure amount when the unit pattern that is not the outermost periphery is exposed once. It is set as follows.

  Here, a unit pattern in which a plurality of pattern blocks each composed of a pair of a transmission pattern and a light shielding pattern are continuously arranged constitutes one of three-dimensional shapes (for example, lenses) formed by exposure. It is. The present invention constitutes an array pattern in which a plurality of the same three-dimensional shapes can be formed by arranging the unit patterns in a matrix. Furthermore, a large number of three-dimensional shapes can be formed in a large area by performing stitch exposure on the array pattern (exposure performed by moving the same pattern stepwise).

  In the present invention, when performing this stitch exposure, the unit patterns that are the outermost circumferences of the array pattern are overlapped with each other in the adjacent exposure region and exposed multiple times (multiple exposure). At this time, since the total exposure amount when the outermost unit pattern is exposed a plurality of times is substantially equal to the exposure amount when the unit pattern that is not the outermost periphery is exposed once, it is overlapped with the unit pattern that is the outermost periphery. Even when stitch exposure is performed together, the exposure amount for the entire array pattern can be made uniform.

  The present invention also relates to a method of manufacturing an exposure mask used in an exposure apparatus, wherein the pattern block is composed of a pair of a light shielding pattern that blocks illumination light emitted from the exposure apparatus and a transmission pattern that transmits the illumination light. Are arranged in succession, and the unit pattern is arranged in a matrix so that the pitch of the continuous pattern block is constant and the ratio between the light shielding pattern and the transmission pattern changes gradually When the array pattern thus formed is provided on the mask substrate, the total light transmission amount when the unit pattern which is the outermost periphery of the array pattern is exposed a plurality of times is the same as when the unit pattern which is not the outermost periphery is exposed once. It is set to be approximately equal to the light transmission amount.

  In the present invention, in the stitch exposure in the array pattern unit, when the adjacent exposure regions are overlapped with the unit pattern that is the outermost periphery of the array pattern, the sum of the outermost unit patterns that are exposed a plurality of times And an exposure mask that can make the exposure amount uniform in a continuous array pattern can be provided. It becomes like this.

  The present invention also relates to a method for exposing a photosensitive material using an exposure mask, and as the exposure mask, a light-shielding pattern that blocks illumination light emitted from the exposure apparatus and a transmission pattern that transmits the illumination light. A unit pattern in which a plurality of pattern blocks composed of pairs of and are arranged in succession, and the pitch of the continuous pattern blocks is constant and the ratio of the light shielding pattern to the transmission pattern is gradually changed And an array pattern in which unit patterns are arranged in a matrix, and a unit pattern whose total light transmission amount is not the outermost periphery when the unit pattern that is the outermost periphery of the array pattern is exposed multiple times. Use an exposure mask that is set to be approximately equal to the amount of light transmitted during a single exposure. After performing one exposure with the array pattern, when performing stitch exposure to an area adjacent to the exposed area, a portion corresponding to the unit pattern that is the outermost periphery of the array pattern in the exposed area, and a new The exposure with the unit pattern which is the outermost periphery of the array pattern in the simple exposure is superposed.

  In the present invention, in the stitch exposure in the array pattern unit, when the adjacent exposure regions are overlapped with the unit pattern that is the outermost periphery of the array pattern, the sum of the outermost unit patterns that are exposed a plurality of times Can be made substantially the same as the one-time exposure amount for the unit pattern that is not the outermost periphery, and the exposure amount can be made uniform between successive array patterns at the stitch exposure boundary portion. It becomes like this.

  According to the present invention, in a three-dimensional device formed by exposing a photosensitive material using an exposure mask, a light shielding pattern for blocking illumination light emitted from an exposure apparatus as the exposure mask, and illumination A plurality of pattern blocks composed of pairs of transmission patterns that transmit light are continuously arranged, and the ratio between the light shielding pattern and the transmission pattern is gradually changed while the pitch of the continuous pattern blocks is constant. A unit pattern that is provided and an array pattern in which the unit patterns are arranged in a matrix, and the total light transmission amount when the unit pattern that is the outermost periphery of the array pattern is exposed a plurality of times is the maximum. Use a unit pattern that is set to be approximately equal to the amount of light transmitted when it is exposed once for a unit pattern that does not become the outer periphery. In the exposure using an exposure mask, after performing one exposure with an array pattern, and then performing stitch exposure to an area adjacent to the exposed area, a unit pattern that is the outermost periphery of the array pattern in the exposed area And the exposure with the unit pattern that is the outermost periphery of the array pattern in the new exposure are overlapped with each other.

  In the present invention, a large number of three-dimensional shapes are formed in a large area by stitch exposure to the photosensitive material. In stitch exposure, when overlapping adjacent exposure areas in the unit pattern that is the outermost periphery of the array pattern, the total exposure amount in the outermost unit pattern that is exposed multiple times and the unit pattern that does not become the outermost periphery Since the exposure amount can be made substantially the same and the exposure amount in a continuous array pattern can be made uniform, a large number of three-dimensional shapes can be formed uniformly.

  The present invention also relates to a method of manufacturing a three-dimensional device by exposing a photosensitive material using an exposure mask, and as the exposure mask, a light shielding pattern for blocking illumination light emitted from an exposure apparatus, and illumination A plurality of pattern blocks composed of pairs of transmission patterns that transmit light are continuously arranged, and the ratio between the light shielding pattern and the transmission pattern is gradually changed while the pitch of the continuous pattern blocks is constant. A unit pattern that is provided and an array pattern in which the unit patterns are arranged in a matrix, and the total light transmission amount when the unit pattern that is the outermost periphery of the array pattern is exposed multiple times is the maximum. Use a unit pattern that is set to be approximately equal to the amount of light transmitted when it is exposed once for a unit pattern that does not have an outer periphery. In the exposure using an exposure mask, after performing one exposure with an array pattern, and then performing stitch exposure to an area adjacent to the exposed area, a unit pattern that is the outermost periphery of the array pattern in the exposed area And the exposure with the unit pattern which is the outermost periphery of the array pattern in the new exposure are overlapped.

  In the present invention as described above, when a large number of three-dimensional shapes are formed in a large area by stitch exposure to a photosensitive material, adjacent exposure regions are overlapped with a unit pattern which is the outermost periphery of the array pattern. At this time, the total exposure amount in the outermost unit pattern exposed a plurality of times and the one-time exposure amount for the unit pattern that does not become the outermost periphery can be made substantially the same. Since the amount of exposure can be made uniform, a large number of three-dimensional shapes can be formed uniformly.

  According to the present invention, the amount of exposure is substantially the same in the overlapping portion in stitch exposure and the other portions, and a large number of three-dimensional devices can be accurately manufactured over a large area. Furthermore, since the ripple-shaped exposure amount error at the time of stitch exposure is designed to be complementarily corrected by a plurality of exposures, the exposure amount error of the overlapping portion can be suppressed to a desired level. . As a result, the entire size of the three-dimensional shape array, which has been limited by the exposure field size of the exposure apparatus in the past, can be expanded to the substrate size (for example, wafer size) for exposure, and can be applied to various products. Is possible.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present embodiment, a lens is described as an example of the three-dimensional device, but the present invention is not limited to this. FIG. 1 is a schematic view for explaining the concept of an exposure mask according to this embodiment. That is, as shown in FIG. 1, this embodiment is suitable for forming lenses, which are one of three-dimensional devices, in an array and in a large area by stitch exposure using a gray scale mask. is there.

  Here, the stitch exposure is exposure performed by step-moving the same pattern. After performing one exposure with the exposure mask M, the exposure range is step-shifted to an area adjacent to the area by the exposure. This is a method of sequentially repeating exposing the same pattern as the previous exposure. Further, in stitch exposure, a part of the region is overlapped by one exposure and the next exposure adjacent thereto, but this overlapped portion (portion that is subjected to multiple exposure) is a stitched portion and no overlap ( A portion that is not subjected to multiple exposure) is referred to as a non-stitched portion.

  The binary grayscale mask, which is the exposure mask M according to the present embodiment, has a pattern block composed of a pair of a light shielding pattern that blocks illumination light emitted from the exposure apparatus and a transmission pattern that transmits the illumination light. A plurality of unit patterns t arranged in a continuous manner and provided so that the ratio of the light shielding pattern to the transmission pattern gradually changes while the pitch of the continuous pattern blocks is constant, and the unit pattern t is a matrix. And an array pattern s arranged in the array.

  In FIG. 1 (a), one thick square frame shown in a grid pattern indicates the unit pattern t, and a plurality of unit patterns t are gathered in a matrix to form one array pattern (thick outer peripheral square) p. ing. In the stitch exposure, one array pattern s is sequentially moved step by step as one exposure area, and is partially overlapped with the adjacent exposure area (see FIG. 1B). For this reason, in the outermost unit pattern constituting the array pattern s, the portion corresponding to the side is combined with the adjacent exposure region for a total of two multiple exposures, and the portion corresponding to the corner is aligned with the adjacent exposure region. In total, multiple exposure is performed four times.

  As described above, in the exposure mask M of the present embodiment, superposition is performed in the unit pattern unit that is the outermost periphery of the array pattern s. Since the unit pattern is a unit constituting one 3D shape (for example, one lens), the alignment error in stitch exposure can be reduced to one 3D shape by superposing multiple exposures in this unit. This is because, as compared with a stitch exposure method that can be absorbed as a whole and does not overlap the boundary portion, the robustness with respect to the alignment error is excellent, so that variation in the exposure amount error of the stitch portion can be reduced as a whole wafer.

  In order to form a large-area lens array by such stitch exposure, in the present embodiment, the total exposure amount when the unit pattern that is the outermost periphery of the array pattern s is exposed multiple times is the unit pattern that does not become the outermost periphery. It is set to be approximately equal to the exposure amount at the time of one exposure.

  Therefore, when the outermost lens element of the lens array is formed by a plurality of exposures, the exposure amount distribution in this portion and the exposure amount distribution for forming the outermost lens element of the lens array are substantially equal. Even in the case of stitch exposure by partial superposition, a large number of three-dimensional devices (for example, lenses) having the same shape can be formed.

  As a specific example, the mask transmittance of the unit pattern corresponding to the outermost lens element of the lens array is set to 1/2 or 1/4 of the mask transmittance of the unit pattern corresponding to the lens element that is not the outermost periphery.

  This point will be described below. As shown in FIG. 1, in the unit pattern that is the outermost periphery of one array pattern, the portions corresponding to the sides are L, R, T, B, and the portions corresponding to the corners are TL, TR, BL, BR. In this case, for the sides L, R, T, and B formed by one-dimensional stitch exposure, as shown in FIG. 2A, a non-stitch portion (a portion that is not subjected to multiple exposure, that is, a unit pattern that is not the outermost periphery). The corner portion formed by two-dimensional stitch exposure is obtained by obtaining a desired exposure amount distribution by two exposures using a mask pattern having a half transmittance of the lens forming pattern of With respect to the lenses TL, TR, BL, and BR, a desired exposure amount distribution is obtained by four exposures with a mask pattern having a transmittance of 1/4 of the lens forming pattern in the non-stitched portion.

  In this embodiment, aperture patterns (transmission patterns) as shown in FIG. 2B are arranged in a matrix as unit patterns t, and the intensity of zero-order light is modulated by changing the aperture ratio, as shown in FIG. This forms a simple lens shape.

  In such an exposure mask M, since one unit pattern t corresponds to one lens shape, a plurality of lens shapes can be formed in an array pattern s in which a plurality of unit patterns t are arranged. . Therefore, more lens shapes can be formed by stitching the exposure area corresponding to the array pattern s.

  As described above, in this embodiment, when performing stitch exposure, overlay exposure is performed in unit patterns in adjacent exposure regions. For this reason, the light transmittance corresponding to the number of times of superimposition is set in the outermost unit pattern for performing the superposition exposure.

  4A and 4B are diagrams showing the relationship between the position of the pattern and the light transmittance. FIG. 4A shows the light transmittance at the arrow A portion shown in FIG. 2A, and FIG. 4B shows the light transmittance shown in FIG. The light transmittance in the arrow B part shown in FIG. Each of the arrow A part and the arrow B part shows a change in light transmittance including a non-stitch part and a light shielding part centering on the outermost unit pattern (stitch part).

  Here, the areas exposed by the outermost unit patterns included in the arrow A part and the arrow B part are parts that are overlapped with each other in the adjacent exposure areas. Therefore, the light transmittance at the arrow A portion shown in FIG. 4A and the light transmittance at the arrow B portion shown in FIG. The light transmittance is set to be the same as the transmittance. In each part, the light transmittance in the unit pattern that is the outermost periphery is ½ of the light transmittance in the unit pattern that is not the outermost periphery.

  Furthermore, in the present embodiment, at the time of stitch exposure, the outermost peripheral lens is configured so that the ripple-like error of the composite exposure amount distribution formed by the outermost lens element forming mask pattern is complementarily corrected by multiple exposures. An element forming mask pattern is designed.

  Here, in order to make the explanation easy to understand, a method of manufacturing an exposure mask and a method of manufacturing a three-dimensional device will be described by taking as an example the case of forming a one-dimensional lens array as shown in FIG. explain.

  The shape of the single-lens lens to be manufactured is a shape as shown in FIG. FIG. 5A shows a mask image. A positive resist is used to form a one-dimensional array of individual lenses having a size of 8 μm and a SAG amount of 4 μm as shown in FIG. 5B. . Further, the lens apex portion is designed to be formed below the offset SAG amount of 1 μm from the remaining film height of the rest unexposed portion.

  First, as shown in FIG. 5A, the lens array is divided into three groups, L, C, and R. The central portion C is not a stitch exposure but a normal single exposure, and has a mask pattern that can obtain the lens shape of FIG. 5B after development.

  The target lens shape of the single lens is assumed to be expressed by the following aspheric equation f (X). In this embodiment, it is assumed that the curvature C = 0.333 (1 / μm) and the conic coefficient K = −0.5, based on the resist height at the center of a single eye.

  Next, an etching rate for the resist / substrate to be used is separately obtained. Here, 1: 1 is assumed for the sake of simplicity. That is, the resist shape is transferred to the substrate as it is after etching.

  Also, the resist to be used is applied to the lens design SAG or more, and the film reduction amount Z (initial film thickness-development film thickness) with respect to the exposure dose (dose) is measured. Decrease characteristic data is obtained. The range E1 to E2 having desired linearity is determined from the data of the film thickness with respect to ln (dose) from the data. As a linear approximation in this range, the following formula 2 is obtained.

  In this embodiment, A = −25 and B = 5.

  Further, as described above, since the etching conversion difference in this material can be ignored, the processing depth f (X) at the coordinate X + offset SAG = f ′ (X) = the resist film reduction amount after development. Therefore, the exposure amount for obtaining the remaining film amount f ′ (X) at the coordinate X is expressed by the following formula 3.

Further, this number 3 is normalized by the maximum exposure value E2, and the target relative transmittance at the coordinate X is obtained as in the following number 4.

  Here, an exposure dose of 403.43 mJ / cm 2 at X = −4 μm was defined as E2.

  Based on the mask transmittance distribution T (X) derived in this way, a mask pattern (unit pattern) within a single eye is designed. First, λ, NA, σ, and magnification of the exposure apparatus to be used are defined. In the present embodiment, it is assumed that an exposure machine having λ = 365 nm, NA = 0.5, σ = 0.5, and a reduction ratio of 1/5 is used. Here, it is assumed that the mask background is 0% transmission (complete light shielding), the line pattern transmittance is 0% (complete light shielding), and the space pattern transmittance is 100% (complete transmission). Further, the subsequent description of the mask pattern dimension is performed with a wafer equivalent value, that is, 1/5 of the actual mask pattern dimension value.

  The resolution limit pitch is calculated to be 487 nm on the wafer based on the conditions of the exposure apparatus described above. Although the number of gradations for controlling the transmittance distribution is preferably as large as possible, it is set to 10 on one side in order to facilitate mask manufacturing. That is, the equivalent pitch of the space pattern on the wafer is 8 um / 20 = 400 nm. Therefore, the mask pattern with this pitch is not resolved, and only the light shielding rate or transmittance of the mask propagates to the wafer surface. Space patterns are arranged at a pitch that is not resolved. Specifically, the element center of the single-lens lens is defined as site 0, and is defined as a multiple pitch of ± 1, ± 2,.

  Next, the 0th-order light intensity when the transmission pattern width is changed at a pitch of 400 nm is calculated. Here, a space width for obtaining a target relative transmittance at each site is obtained from the target exposure distribution (Equation 3). That is, with respect to the site m, the center X coordinate of the space pattern is mP, and the target relative transmittance at this coordinate is obtained from Equation 4 as T (mP) = 1 / E2 × D (mP). A space pattern width (space width in Table 1) with a pitch P = 400 nm for obtaining T (mP) is obtained. Thereby, the space pattern width at each site in the single lens is obtained. An actual calculation example here is shown in Table 1.

  Next, the design of the mask pattern for forming the lens element L portion and R portion formed by stitch exposure will be described. In this part, since it is necessary to obtain the exposure amount distribution given to the above-mentioned part C by two exposures, the transmittance of 1/2 of T (X) calculated in Table 1 is obtained. Obtain the resulting space pattern. This is shown in Table 2.

  Here, as shown in FIG. 7, the space pattern at the boundary between the lenses of the CL portion and the R portion and the CR portion and the L portion is shared, but here, the L portion X = + 4 μm, and the R portion X = The space pattern is not disposed at −4 μm, and the transmittance is controlled by the space pattern CP disposed at −4 μm of the CR part and +4 μm of the CL part, respectively.

  At this time, the simulation results of the mask transmittance of the R portion and the L portion in the mask pattern shown in Table 2 are shown in FIG. 8A and FIG. 8B. That is, at this time, the pattern of X = ± 4 μm in Table 1 is used, and CP = 330 nm.

  Further, FIG. 8C shows the transmittance distribution (broken line) targeted for the simulation result (solid line) of the exposure amount distribution when the CR + R portion and CL + L portion are subjected to overlap exposure, that is, stitch exposure.

  From the result, it can be seen that although there is a slight transmittance error in the circled portion, almost the target transmittance distribution is obtained.

  Further, using this transmittance distribution, in order to obtain a resist exposure amount of 403.43 mJ / cm 2 at coordinates X = ± 12 μm where the transmittance is 0.68, the resist shape when exposed at a set exposure amount of 593 mJ / cm 2 is obtained. FIG. 9 shows the calculation result (solid line), the target surface function (Formula 1, broken line), and the surface shape error (one-dot broken line). Thereby, it can be seen that the surface shape error is suppressed to −0.6 μm to +0.43 μm.

  Next, a measure for reducing the ripple-shaped surface shape error in the circled portion of FIG. 8C described above, that is, the stitch exposure portion will be described.

  Returning to FIG. Now, in order to reduce the ripple-like transmittance error at the time of stitch exposure using the transmittance error at the time of stitch exposure in the vicinity of the coordinates of L portion +4 μm as an index, the CP portion CL of FIG. The ripple of the composite transmittance is reduced by finely adjusting the space pattern of CP of X = −4 μm in the CR portion.

  Here, a mask pattern in which the space size of the CP was swung as shown in Table 3 was created, and the combined transmittance when stitch exposure was performed in the same manner as described above was calculated, and an error with respect to the target transmittance was calculated. The results are shown in FIG. 10 in the region where X = 0 to 8 μm. In addition, Table 3 shows the error range (maximum-minimum) and standard deviation for each CP size.

  From this result, it can be seen that the transmittance error can be further reduced at 338 nm than at CP = 330 nm in the first example.

  In this way, by finely adjusting the space pattern at the lens boundary part to be stitched, the composite transmittance at the time of stitch exposure, that is, the error of the composite exposure amount can be reduced, and the error of the formed resist shape can also be reduced. It can be reduced.

  Further, here, CP has been described with only one space pattern at the boundary, but the ripple-shaped combined transmittance error at the boundary can be reduced with higher accuracy by dimensional fine adjustment of a plurality of patterns.

  By using the exposure mask designed and manufactured in this manner and performing stitch exposure, a large number of single-lens lenses are formed in a large area. At this time, the region that becomes the stitch exposure seam can realize substantially the same lens shape as the region that does not become the seam, and it is possible to manufacture a highly accurate array lens in which the ripple at the boundary is suppressed.

  By the way, in the embodiments described so far, the stitch exposure of the one-dimensional lens array has been dealt with for the sake of simplicity of explanation. However, the mask is formed with respect to the stitch exposure of the two-dimensional lens array as shown in FIG. Is a hole array (dark field) or a dot array (clear field), but may be expanded in the same way. In addition, although the example in which the light transmittance of the stitch portion is ½ or ¼ of the light transmittance of the non-stitch portion has been described, the total light transmittance amount by the multiple exposure at the stitch portion is Other than the above, it may be designed so as to be almost equal to the light transmission amount by one exposure at the stitch portion.

  In the microlens array manufacturing method described so far, an example in which a substrate is processed by etching after forming a three-dimensional photoresist shape is used. However, a mother die is produced by electroforming a photoresist. It is also possible to mass-produce with the stamper method. The lens array formed with the mask of this embodiment can be applied to CCDs, other liquid crystal display devices, semiconductor lasers, light receiving elements, and optical communication devices other than image devices such as liquid crystal projectors. The present invention can also be applied to manufacture of a three-dimensional shape other than the above, that is, a so-called MEMS (Micro Electro Mechanical Systems) / NEMS (Nano Electro Mechanical Systems) device.

  Further, in this embodiment, for the sake of simplicity, the mask pattern design method has been described using a method using a theoretical value of the aperture ratio. However, this was proposed in a previous application (Japanese Patent Application No. 2003-281489) by the present inventor. As described above, the present invention is also effective in a method using the residual film characteristics obtained by exposing the calibration mask. In this case, the calibration mask is exposed at Emax in the same manner as the actual exposure described above, and this sample wafer is developed to obtain correlation data of the pattern dimension versus the film reduction amount. You may make it perform the pattern design of a gray tone pattern using this correlation data.

  The present invention can be applied to a three-dimensional object such as a switch, a relay, or a sensor using MEMS / NEMS. Furthermore, the present invention can be applied to the formation of a substrate base shape in semiconductor manufacturing or the like.

It is a schematic diagram explaining the concept of the mask for exposure which concerns on this embodiment. It is a schematic diagram which shows the example of a mask. It is a schematic diagram which shows the example of a mask and a lens shape. It is a schematic diagram explaining the light transmittance in a stitch part and a non-stitch part. It is a schematic diagram explaining the mask of a one-dimensional lens array. It is a schematic diagram which shows the exposure characteristic of a resist. It is a schematic diagram explaining the mask pattern for stitch part formation. It is a figure which shows the transmittance | permeability distribution calculation result of a stitch part. It is a figure which shows a resist shape calculation result. It is a figure which shows the calculation result of a synthetic | combination transmittance | permeability error. It is a schematic diagram explaining the process of micro lens formation. It is a schematic diagram explaining the multiple exposure of a several mask. It is a schematic diagram explaining a gray tone mask. It is a schematic diagram explaining the principle of a binary type gray tone mask.

Explanation of symbols

  M: exposure mask, t: unit pattern, s: array pattern

Claims (9)

In an exposure mask used in an exposure apparatus,
A plurality of pattern blocks each composed of a pair of a light shielding pattern that blocks illumination light emitted from the exposure apparatus and a transmission pattern that transmits the illumination light are continuously arranged, and A unit pattern provided with a constant pitch and a ratio of the light-shielding pattern and the transmission pattern gradually changing;
An array pattern in which the unit patterns are arranged in a matrix,
The total light transmission amount when the unit pattern that is the outermost periphery of the array pattern is exposed a plurality of times is set to be approximately equal to the light transmission amount when the unit pattern that is not the outermost periphery is exposed once. An exposure mask characterized by that. 2. The exposure mask according to claim 1, wherein the pitch of the continuous pattern blocks is such that light reaching the imaging plane via the pattern blocks is only zero-order light. When the pitch of the continuous pattern block is P (exposure surface conversion), the exposure wavelength of the exposure apparatus is λ, the numerical aperture of the exposure apparatus is NA, and the coherence factor indicating the secondary light source size is σ,
P <λ / {NA × (1 + σ)}
The exposure mask according to claim 1, wherein: The light transmittance of the unit pattern that is the outermost periphery of the array pattern is 1/2 or 1/4 of the light transmittance of the unit pattern that is not the outermost periphery. mask. In a method for manufacturing an exposure mask used in an exposure apparatus,
A plurality of pattern blocks each composed of a pair of a light shielding pattern that blocks illumination light emitted from the exposure apparatus and a transmission pattern that transmits the illumination light are continuously arranged, and A unit pattern provided with a constant pitch and a ratio of the light-shielding pattern and the transmission pattern gradually changing;
In providing the mask substrate with an array pattern in which the unit patterns are arranged in a matrix,
The total light transmission amount when the unit pattern that is the outermost periphery of the array pattern is exposed a plurality of times is set to be substantially equal to the light transmission amount when the unit pattern that is not the outermost periphery is exposed once. A method for producing an exposure mask characterized by the above. The light transmittance of one or more pattern blocks constituting the boundary portion between the unit pattern that is the outermost periphery of the array pattern and the unit pattern that is not the outermost periphery is the combined light transmittance distribution by the multiple exposure. 6. The method of manufacturing an exposure mask according to claim 5, wherein the correction is performed according to the target light transmittance distribution. In a method of exposing a photosensitive material using an exposure mask,
As the exposure mask,
A plurality of pattern blocks composed of a pair of a light-shielding pattern that blocks illumination light emitted from the exposure apparatus and a transmission pattern that transmits the illumination light are continuously arranged, and the pitch of the continuous pattern blocks Is a unit pattern formed so that the ratio between the light shielding pattern and the transmission pattern is gradually changed, and
An array pattern in which the unit patterns are arranged in a matrix,
The total light transmission amount when the unit pattern that is the outermost periphery of the array pattern is exposed a plurality of times is set to be approximately equal to the light transmission amount when the unit pattern that is not the outermost periphery is exposed once. Use what
In the exposure using the exposure mask, after performing one exposure with the array pattern and then performing stitch exposure to an area adjacent to the exposed area, the outermost periphery of the array pattern in the exposed area An exposure method comprising superimposing a portion corresponding to the unit pattern and an exposure with the unit pattern which is the outermost periphery of the array pattern in a new exposure. In a three-dimensional device formed by exposing a photosensitive material using an exposure mask,
As the exposure mask,
A plurality of pattern blocks composed of a pair of a light-shielding pattern that blocks illumination light emitted from the exposure apparatus and a transmission pattern that transmits the illumination light are continuously arranged, and the pitch of the continuous pattern blocks Is a unit pattern formed so that the ratio between the light shielding pattern and the transmission pattern is gradually changed, and
An array pattern in which the unit patterns are arranged in a matrix,
The total light transmission amount when the unit pattern that is the outermost periphery of the array pattern is exposed a plurality of times is set to be approximately equal to the light transmission amount when the unit pattern that is not the outermost periphery is exposed once. Use what
In the exposure using the exposure mask, after performing one exposure with the array pattern and then performing stitch exposure to an area adjacent to the exposed area, it becomes the outermost periphery of the array pattern in the exposed area. The three-dimensional device, wherein the portion corresponding to the unit pattern and the exposure with the unit pattern which is the outermost periphery of the array pattern in a new exposure are overlapped. In a method of manufacturing a three-dimensional device by exposing a photosensitive material using an exposure mask,
As the exposure mask,
A plurality of pattern blocks composed of a pair of a light-shielding pattern that blocks illumination light emitted from the exposure apparatus and a transmission pattern that transmits the illumination light are continuously arranged, and the pitch of the continuous pattern blocks Is a unit pattern formed so that the ratio between the light shielding pattern and the transmission pattern is gradually changed, and
An array pattern in which the unit patterns are arranged in a matrix,
The total light transmission amount when the unit pattern that is the outermost periphery of the array pattern is exposed a plurality of times is set to be approximately equal to the light transmission amount when the unit pattern that is not the outermost periphery is exposed once. Use what
In the exposure using the exposure mask, after performing one exposure with the array pattern and then performing stitch exposure to an area adjacent to the exposed area, it becomes the outermost periphery of the array pattern in the exposed area. A method for manufacturing a three-dimensional device, characterized in that a portion corresponding to the unit pattern and an exposure with the unit pattern which is the outermost periphery of the array pattern in a new exposure are overlapped.

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