JP4396320B2 - Method for producing blazed diffraction grating, blazed diffraction grating and optical sheet - Google Patents

Description

  The present invention relates to a method for manufacturing a blazed diffraction grating using a charged particle beam by an electron beam drawing apparatus or the like, and more specifically, a blazed type having a high-quality saw blade shape by changing the number of scans of the charged particle beam. The present invention relates to a method for manufacturing a diffraction grating.

  An optical sheet with a diffraction grating on the surface of the substrate can control the direction of light emission using the light diffraction function, so it can be used for display purposes, security applications for the purpose of preventing counterfeiting, and electronic display equipment. It is widely used for light control films.

  A binary type diffraction grating used for an optical sheet of such a diffraction grating has a rectangular or sinusoidal cross section, a typical grating pitch is about 0.5 to 2 μm, and a grating depth is about 0.1 to 1 μm. It is. When light is incident perpendicularly to a binary diffraction grating having a rectangular or sinusoidal cross-sectional shape, the diffracted light has a + n-order direction and −n as shown in FIGS. 1 (a) and 1 (b), respectively. The light is distributed almost uniformly in the next direction, the light amount of ± first-order diffracted light is the largest, and the light amount decreases as the order increases.

  Up until now, optical sheets using this type of diffraction grating were generally used as optical sheets using a diffraction grating. However, with a binary type diffraction grating, sufficient diffraction efficiency cannot be obtained, and many diffracted lights vary. It was a problem that it was ejected in any direction.

  On the other hand, as shown in FIG. 2 (a), a blazed diffraction grating has a typical grating pitch and grating depth equivalent to those of a binary diffraction grating, but its cross-sectional shape is a saw blade, When the diffraction angle and the reflection angle of the light from the inclined surface coincide with the incident light, diffracted light having a theoretical diffraction efficiency of 100% is generated in that direction, and light is not emitted at other angles. There is. That is, the blazed diffraction grating has characteristics that it can obtain a very high diffraction efficiency as compared with the binary diffraction grating and that the traveling angle of light can be strictly controlled.

As a parameter of the blazed diffraction grating,
(1) Spatial frequency of diffraction grating (grating interval (pitch) of grating lines)
(2) Direction of diffraction grating (direction of grating line)
(3) There are three tilt angles of the diffraction grating,
According to (1), the color at which the diffraction grating appears shining with respect to a fixed point changes,
In accordance with (2), the direction in which the diffraction grating appears shining changes,
In accordance with (3), the angle at which the diffraction grating appears to shine changes.

  In addition, as shown in FIG. 2B, a blazed diffraction grating whose cross-sectional shape is stepped only on one side is slightly inferior to the blazed diffraction grating having a saw-tooth cross-sectional shape, but is similarly high. Diffracted light having diffraction efficiency can be obtained.

  As an invention using a conventional blazed diffraction grating, a display in which the display area is divided into a matrix and a blazed diffraction grating with various spatial frequencies and / or directions changed for each small area is proposed. (For example, refer to Patent Document 1).

As a method for producing a blazed diffraction grating, an exposure apparatus using a charged particle beam such as an electron beam lithography apparatus is used, and a blazed diffraction grating is formed on a planar substrate placed on a stage by computer control. A method of forming a shape is known. For example, if a substrate coated with a positive photosensitive material is irradiated with a charged particle beam and developed, a concave shape can be obtained, but the irradiation time of the charged particle beam can be increased or the strength can be increased. Deeper processing can be performed with, and conversely shallow processing can be performed by shortening the irradiation time of the charged particle beam or decreasing the intensity.

  Using such a method, the sawtooth shape of the blazed diffraction grating can be obtained by moving the charged particle beam at a minute interval (step) in the direction orthogonal to the grating line and controlling the intensity at each point. . FIG. 3 shows an example of a method for producing a blazed diffraction grating by such a method. The electron beam is scanned in the direction of the grating line of the blazed diffraction grating as shown in FIG. 3A, and then the electron beam irradiation position in a minute step in the direction perpendicular to the direction of the grating line as shown in FIG. Are gradually moved, and the diffraction grating is formed by repeatedly scanning the electron beam as shown in FIG. Here, when performing the electron beam irradiation for each step shown in FIG. 3B, the shape of the blazed diffraction grating can be obtained by changing the irradiation energy amount of the electron beam for each step. As a method of changing the irradiation energy amount of the electron beam, a method of monotonically increasing the number of scans once, twice, or three for each step, a method of changing the scanning speed for each step, and the like have been proposed. Yes. A blazed diffraction grating manufactured by such a method has a stepped shape in principle, but by setting the steps sufficiently finely, the charged particle beam is scattered within the resist and the proximity effect that sensitizes the surrounding area. Also, by optimizing the development conditions, a blazed diffraction grating having a smooth slope and high diffraction efficiency can be produced.

  In FIG. 3, the positive resist 12 is drawn so that the shape of a blazed diffraction grating is obtained by irradiation with a charged particle beam. This is conceptually a manufacturing method using a charged particle beam. Strictly speaking, the shape of the blazed diffraction grating can be obtained by performing an appropriate development process after drawing with a charged particle beam.

  In addition, a method is known in which a plurality of mask patterns are prepared in advance and a photosensitive material (resist), glass or the like is etched using them. FIGS. 4A to 4C are sectional views showing an example of a blazed diffraction grating manufacturing process using a mask pattern, and a stepped blazed diffraction consisting of an 8-stage structure with three masks. A lattice is formed. As shown in FIGS. 4A to 4C, on the positive resist 12 applied to the substrate 11, a mask 13 having different opening sizes is placed in close contact, and etched. A stair-shaped blazed diffraction grating is obtained. In general, 2 n steps can be formed by repeating etching n times with n masks. The theoretical diffraction efficiency when n = 1, 2, 3, 4 is about 41, 81, 95, 99%, respectively.

Patent documents are described below.
JP 2000-39508 A

  In the method of using the charged particle beam as described above and monotonically increasing the number of scans for each step, it is difficult to obtain a cross-sectional shape having a desired depth stepwise. This is because the photosensitive material (resist) used in this method usually cannot obtain a perfect proportional relationship between the change in the amount of irradiation energy of the beam and the remaining film thickness after development. Therefore, in principle, it is difficult to obtain a blazed diffraction grating having an ideal cross-sectional shape with this method.

  In addition, the blazed diffraction grating formed by the method using charged particle beam as described above or the method using ion beam etching, etc. is used to create a metal plate that can withstand multiple uses as a master for duplication. Then, it can be mass-produced by making a molding material such as a thermoplastic resin, an ultraviolet curable resin, an electron beam curable resin or the like adhere to a metal plate or the like and cure.

  Here, it is difficult to completely duplicate the complicated fine pattern of the original plate due to characteristics such as viscosity and compatibility with the original material. In particular, it is often impossible to perform good duplication when the concave / convex pattern is complicated and irregular, or when the concave portion is deep. In addition, warping and shrinkage due to the characteristics of the molding material during curing also cause complete replication. Therefore, even if an ideal blazed diffraction grating is formed as an original, there arises a problem that ideal optical characteristics cannot be obtained in a duplicate.

  Since the problem as described above appears more prominently when a complicated original plate shape is duplicated, as a cross-sectional shape of the blazed diffraction grating, a stepped diffraction grating as shown in FIG. A saw blade-shaped diffraction grating having a smooth slope as shown in FIG. 2A is more desirable, and more accurate replication can be expected.

  In addition, considering the warping and shrinkage at the time of duplication, the sloped part of the blazed diffraction grating of the original plate should be slightly protruded or processed into a concave shape so that the duplicated product has the best cross-sectional shape. It is also effective to obtain an ideal blazed diffraction grating during replication. Such processing of the original plate in consideration of deformation at the time of duplication is difficult to realize with a stepped blazed diffraction grating.

  Therefore, it is desirable that the blazed diffraction grating has a saw-blade shape with a smooth slope, and in order to produce such a blazed diffraction grating, measures must be taken to control and process the cross-sectional shape with high precision. Is desirable. If the method using the charged particle beam such as the electron beam drawing apparatus described above is used, it is possible to scan the charged particle beam with a very high resolution of 0.1 μm or less, thereby reducing the processing depth at that point for each step. Since it can be determined, it is possible to obtain a blazed diffraction grating having an intended cross-sectional shape.

  The present invention provides a method for producing a blazed diffraction grating using a charged particle beam, such as an electron beam lithography system, by changing the number of scans of the charged particle beam for each step based on a certain rule, thereby having an intended cross-sectional shape. It is an object of the present invention to provide a method for producing a blazed diffraction grating with high accuracy.

  The method for producing a blazed diffraction grating according to claim 1 scans a charged particle beam on a photosensitive material, controls the irradiation energy amount of the beam step by step in a scanning region, and draws the diffraction grating. In the method for manufacturing a blazed diffraction grating having a forming step, the number of scans per step of the charged particle beam is set to a predetermined real number, and another real number having a value after the predetermined decimal point is set to one step. It is characterized in that each value after the decimal point is rounded down, rounded up, rounded off or rounded or converted into an integer according to a certain rule for each value added or subtracted or calculated according to a certain rule every time.

  A blazed diffraction grating manufacturing method according to a second aspect is characterized in that, in the method according to the first aspect, a distance between steps of the charged particle beam is proportional to a grating interval of the blazed diffraction grating.

  The method for producing a blazed diffraction grating according to claim 3 is characterized in that, in the method according to claim 1, the distance between steps of the charged particle beam is constant.

  The method for producing a blazed diffraction grating according to claim 4 is characterized in that, in the method according to claim 1, the distance between steps of the charged particle beam becomes narrower toward the deepest part of the blazed diffraction grating. Yes.

The method for producing a blazed diffraction grating according to claim 5 is the method according to claim 1,
The distance between the steps of the charged particle beam is narrowed toward the shallowest part of the blazed diffraction grating.

The method for producing a blazed diffraction grating according to claim 6 is the method according to claim 1,
The distance between the steps of the charged particle beam varies locally.

The method for producing a blazed diffraction grating according to claim 7 is the method according to any one of claims 1 to 6,
The number of steps for one lattice line of the charged particle beam is three times or more.

The blazed diffraction grating according to claim 8, wherein the original is produced by scanning with a charged particle beam.
The lattice pattern as a structural unit has a cross-sectional shape in which the depth is changed substantially in a step shape according to the column in which the charged particle beam is scanned,
The height difference between the adjacent rows is not constant within one lattice pattern.

  An optical sheet comprising the blazed diffraction grating according to claim 9 is produced by the method for producing a blazed diffraction grating according to any one of claims 1 to 8.

The method for producing a blazed diffraction grating of the present invention can be expected to have the following effects by the steps described above.
(1) The number of scans per step is rounded down to a value obtained by adding or subtracting a real number having a predetermined decimal point to another predetermined real number. Or, rounding up, rounding off, or making it an integer by a fixed rule, so it is possible to control the amount of irradiation energy at each step more strictly than the number of scans based on conventional addition or subtraction of simple integer values. A blazed diffraction grating having the expected cross-sectional shape can be produced. That is, the conventional method for determining the number of scans is monotonically increasing with a tolerance of 1, 2, 3, 4,..., But according to the method proposed by this patent, 1, 1, 2, 3 , 3,... Are not constant and the number of scans in each step can be obtained, so that the cross-sectional shape can be controlled more freely.
(2) When the blazed diffraction grating manufacturing method according to claim 1 is carried out, the number of steps is changed in proportion to the grating interval of the blazed diffraction grating, so that it is substantially the same regardless of the length of the grating interval. A blazed diffraction grating can be produced in the drawing time. Also, when drawing a grid with a long grid interval, the step becomes too rough to obtain the desired grid shape, or when drawing a grid with a narrow grid interval, the step becomes too fine and the proximity effect during exposure Can avoid the adverse effect of lattice formation.
(3) When the blazed diffraction grating manufacturing method according to claim 1 is carried out, the blazed diffraction grating is manufactured with the same resolution regardless of the location by making the distance between steps of the charged particle beam constant. Can do.
(4) When the blazed diffraction grating manufacturing method according to claim 1 is carried out, the distance between steps of the charged particle beam is narrowed toward the deepest part of the blazed diffraction grating, so that the shape around the deepest part is obtained. Control can be performed more accurately than other parts.
(5) When carrying out the blazed diffraction grating manufacturing method according to claim 1, the distance between steps of the charged particle beam is narrowed toward the shallowest portion of the blazed diffraction grating, so that the periphery of the shallowest portion The shape control in can be performed more accurately than other parts.
(6) In carrying out the blazed diffraction grating manufacturing method according to claim 1, the distance between the steps of the charged particle beam is roughened where the formation accuracy of the blazed diffraction grating is not so required, and the formation is high. When the accuracy is required, the drawing time can be shortened by making it fine, or the formation accuracy can be varied depending on the location.
(7) When performing the method for producing a blazed diffraction grating according to any one of claims 1 to 6, the number of steps of the charged particle beam with respect to one grating line is set to 3 or more, A blazed diffraction grating having a smooth slope and sufficient diffraction efficiency can be produced.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  An embodiment of a method for producing a blazed diffraction grating according to claim 1 will be described. 2. The method for manufacturing a blazed diffraction grating according to claim 1, wherein the number of scanning of the charged particle beam for each step is added to or subtracted from a predetermined real number and another predetermined number after the decimal point. The value obtained by rounding down or rounding up or rounding off or rounding the value after the decimal point or making it an integer by a certain rule is a feature. For example, a standard real number is set to 1.0 and another real number having a value after the decimal point is set to 0.4. In this case, when the other real number is added to the reference real number, 1.0, 1.4, 1.8, 2.2, 2.6, 3.0, 3.4, 3.8 , 4.2, 4.6, 5.0,... If these real numbers are rounded down to the nearest whole number, the integers 1,1,1,2,2,3,3,3,4,4,5, ... are obtained. be able to. By setting this as the number of scans of the charged particle beam for each step, it becomes easier to control the cross-sectional shape as compared with the conventional drawing method in which the number of scans is determined in an arithmetic sequence. FIG. 5 shows a black line 31 as an example of the processing state of the positive resist 12 when a blazed diffraction grating is drawn by the number of scannings of the charged particle beam determined by the above method. The state of scanning with the charged particle beam is the same as that shown in FIG. FIG. 5 shows a gray line 32 as an example of the processing state when the number of scans is determined in the conventional arithmetic progression. As is apparent from the figure, the drawing method of this patent indicated by the black line 31 shows that a cross section having a gentler slope angle than that of the conventional method indicated by the gray line 32 is obtained. That is, if the manufacturing method of this patent is used, even if it is a charged particle beam with the same energy amount, the cross section of an angle different from the conventional method can be obtained. In FIG. 5, the sawtooth shape of one grid line is formed by drawing in 10 steps, and the set of integers derived by the method for determining the number of scans uses the tenth numerical value, and thereafter 1 Returning to the 10th value, the 10th is used in the same way.

Similarly, when the real number used as a reference is set to 1.0, the other real numbers are set to 0.6, and the addition is repeated, the set of real numbers is 1.0, 1.6, 2.2, 2.8, 3 .4, 4.0, 4.6, 5.2, 5.8, 6.4, 7.0,..., 1,1,2,2,3,4,4,5 An integer set of 5, 6, 7,... Is obtained. When the number of scans of the charged particle beam is determined from the set of integers, the processing state of the positive resist 12 is as shown by a solid line 33 in FIG. 6, and is an intermediate between blazed diffraction gratings obtained by both drawing methods shown in FIG. Can be obtained. In this way, it is possible to control the cross-sectional shape of the blazed diffraction grating by arbitrarily setting a real number serving as a reference and a real number having a value after the other decimal point. Needless to say, reducing the real number having a value after the decimal point makes it difficult to increase the number of scans, and conversely increasing the real number having a value after the decimal point makes it easier to increase the number of scans. In addition, the real number used as a reference | standard here may have a value below a decimal point, and may be an integer. In addition, the calculation of the reference real number and the other real number having a value after the decimal point is not only addition, but subtraction, multiplication, division, square root, etc. Since the number of times can be regularized and the cross-sectional shape of the blazed diffraction grating can be controlled, various operations can be selected and used. In addition to using only one operation, one operation may be performed multiple times, multiple types of operations may be performed, or multiple real numbers may be prepared and operations may be performed on them. .

  As still another embodiment, when the subtraction is repeated with 12.7 as the reference real number and 1.3 as the other real number, 12.7, 11.4, 10.1, 8.8, 7. 5, 6.2, 4.9, 3.6, 2.3, 1.0,..., Rounded to the nearest decimal point, 13, 11, 10, 9, 8, 6, 5, 4, 2, 1. A pair of integers is obtained. When this set is assigned to the number of scannings of the charged particle beam for each step, a blazed diffraction grating having a cross-sectional shape as shown in FIG. 7 can be obtained. In this case, deeper processing can be performed with the same amount of energy as compared with the conventional drawing method in which the number of scans is determined in a sequence of equality sequences. In this case, since subtraction is used as the calculation, a blazed diffraction grating in the direction opposite to the method of FIGS. 5 and 6 using addition is produced.

  Thus, by using the manufacturing method according to claim 1, it is possible to cope with the characteristics of the photosensitive material (resist) in which a proportional relationship cannot be obtained between the irradiation energy amount of the charged particle beam and the residual film thickness after development. A blazed diffraction grating having an ideal cross-sectional shape can be produced with a desired grating depth.

  The blazed diffraction grating manufacturing method according to claim 2 is characterized in that when the manufacturing method according to claim 1 is carried out, the step interval for each grating line is changed in proportion to the grating interval of the blazed diffraction grating. It is said. FIG. 8 shows a conceptual diagram of a method for producing a blazed diffraction grating according to claim 2. The right blazed diffraction grating in FIG. 8 has a wide grating interval, and the left grating in FIG. 8 has a narrow grating interval. Here, the step interval 13 is changed according to the length of the lattice interval, and the number of steps (number of electron beam irradiation positions) for one lattice line is made the same regardless of the length of the lattice interval. In FIG. 8, the number of steps is 4 respectively. When drawing with the same number of steps for one grid line regardless of the length of the grid spacing, when drawing a grid with a long grid spacing, the steps become too rough and the desired grid shape cannot be obtained, When drawing a narrow grating, there is a concern that the step becomes too fine and the proximity effect during exposure adversely affects the formation of the grating, but the method for producing a blazed diffraction grating according to claim 2 By using it, the influence of these phenomena can be avoided or reduced. In addition, the drawing time can be prevented from changing greatly due to the length of the lattice interval.

  For example, when a grid with a grid interval of 2 μm is drawn by moving the electron beam irradiation position in steps of 0.2 μm, and simultaneously a grid with a grid interval of 1 μm is drawn in steps of 0.1 μm, one grid line Is drawn in 10 steps.

  The method for producing a blazed diffraction grating according to claim 3 is characterized in that the step interval is constant when the production method according to claim 1 is carried out. By making the step interval constant, a blazed diffraction grating can be produced with the same resolution regardless of the location and the grating interval of the blazed diffraction grating.

The blazed diffraction grating manufacturing method according to claim 4 is characterized in that the step interval becomes narrower toward the deepest portion of the blazed diffraction grating. FIG. 9 shows a conceptual diagram of charged particle beam scanning in the method for producing a blazed diffraction grating according to claim 4. As shown in FIG. 9, the shape control can be performed with higher accuracy toward the deepest part by narrowing the step interval as the number of times of scanning of the charged particle beam increases.

  The blazed diffraction grating manufacturing method according to claim 5 is characterized in that the step interval becomes narrower toward the shallowest portion of the blazed diffraction grating. FIG. 10 shows a conceptual diagram of charged particle beam scanning in the method for producing a blazed diffraction grating according to claim 5. As shown in FIG. 10, the shape control can be performed with higher accuracy in the vicinity of the shallowest portion by reducing the step interval as the number of times of scanning with the charged particle beam decreases.

  Since the deepest and shallowest parts of the blazed diffraction grating have a sharp shape, when making a replica with molding materials such as thermoplastic resin, the resin does not penetrate deeply and cannot be replicated accurately. Or the tip may be chipped when the cured resin is peeled off. If such lattice-shaped defects occur unevenly depending on the location, there is a risk that the quality of the light will deteriorate due to unevenness in the amount of light emitted from the duplicate. Therefore, if the blazed diffraction grating manufacturing method according to any one of claims 4 to 5 is carried out and the deepest part and the shallowest part of the blazed diffraction grating are rounded in advance, the above-mentioned defects can be prevented or reduced. It is.

  The blazed diffraction grating manufacturing method according to claim 6 is characterized in that the step interval is locally changed at a specific portion in the grating line. As described above, a blazed diffraction grating having a desired cross-sectional shape may not be obtained due to the residual film thickness characteristics after development with respect to the irradiation energy amount of the photosensitive material (resist), the proximity effect around the beam irradiation portion, and the like. . Considering this, a blazed diffraction grating having an ideal cross-sectional shape can be obtained by changing the step interval in a specific portion by the same method as that shown in the manufacturing method of claims 4 to 5. .

  As already described, a blazed diffraction grating can obtain a diffraction efficiency of 95% or more as a theoretical value if the number of steps is three or more for one grating line. Therefore, as described in claim 7, in the method for manufacturing a blazed diffraction grating according to this patent, sufficient diffraction efficiency can be obtained by setting the number of steps of the charged particle beam for one grating line to three or more. A lattice can be made. In general, a blazed diffraction grating having a spatial frequency in the range of about 500 to 1500 lines / mm (about 2.0 to 0.67 μm when converted to a grating interval) is practical. That is, the step interval may be 0.66 μm or less when the spatial frequency is 500 lines / mm and 0.22 μm or less when the spatial frequency is 1500 lines / mm.

  In the blazed diffraction grating fabrication method proposed in this patent described so far, the scanning direction of the charged particle beam has been shown as a straight line, but the same applies to a curved blazed diffraction grating. The manufacturing method can be implemented, and the same effect can be expected.

  As described above, the blazed diffraction grating produced by the method described in any one of claims 1 to 7 can be duplicated as an optical sheet using a thermoplastic resin, an ultraviolet curable resin, or the like as a molding material. This optical sheet can be widely used for display applications, security applications for the purpose of preventing counterfeiting, light control films for electronic display devices, and the like.

(A) is explanatory drawing which shows the mode of diffraction of the binary type diffraction grating whose cross section is rectangular shape, (b) is explanatory drawing which shows the mode of diffraction of the binary type diffraction grating whose cross section is sinusoidal shape. (A) is explanatory drawing which shows the mode of diffraction of the blazed diffraction grating whose cross section is saw-tooth shape, (b) is explanatory drawing which shows the mode of diffraction of the blazed diffraction grating whose cross section is stepped. (A) is a conceptual diagram which shows the mode of a process with respect to the lattice line direction at the time of forming a blazed diffraction grating using a charged particle beam, (b) is a conceptual diagram which shows the mode of a process with respect to the direction orthogonal to a lattice line. . (A), (b), (c) is explanatory drawing which shows the etching process at the time of forming a blazed diffraction grating by an etching method in order of a process, respectively. It is explanatory drawing which shows an example of the preparation method of the blazed diffraction grating of this patent proposal which prescribes | regulates the frequency | count of scanning for each step according to a fixed law, and forms a blazed diffraction grating. It is explanatory drawing which shows an example of the preparation methods which apply the scanning frequency determination rule different from FIG. 5, and form a blazed diffraction grating. FIG. 7 is an explanatory diagram showing an example of a manufacturing method for forming a blazed diffraction grating by applying a scanning frequency determination rule different from that in FIGS. 5 and 6. It is explanatory drawing which shows an example of the manufacturing method of the blazed diffraction grating of this invention which changes and draws a step space | interval according to the grating | lattice space | interval of a blazed diffraction grating. It is explanatory drawing which shows an example of the manufacturing method of the blazed diffraction grating of this invention which draws by narrowing a step space | interval as it goes to the deepest part of a blazed diffraction grating. It is explanatory drawing which shows an example of the preparation method of the blazed diffraction grating of this invention which draws by making a step space | interval narrow as it goes to the shallowest part of a blazed diffraction grating.

Explanation of symbols

Binary diffraction grating 02 having a rectangular cross section 02 Binary diffraction grating 03 having a sinusoidal cross section blazed diffraction grating 04 having a saw-blade cross section blazed diffraction grating 11 having a stepped cross section 11 Substrate 12 A positive resist 13 ... charged particle beam 14 ... charged particle beam scanning direction 15 ... charged particle beam drawing direction 16 ... charged particle beam step interval 20 ... mask 21 ... exposure light 31 ... shallow grating angle processed by the manufacturing method of the present invention. Cross-sectional shape of lattice 32 ... Cross-sectional shape of lattice processed by conventional method 33 ... Cross-sectional shape of lattice with slightly shallow lattice angle processed by the manufacturing method of the present invention 34 ... Grid angle processed by the manufacturing method of the present invention Cross section shape of deep lattice

Claims (7)

In a method for producing a blazed diffraction grating, the method includes a step of scanning a charged particle beam on a photosensitive material, controlling the irradiation energy amount of the beam step by step for each scanning area, and drawing and forming the diffraction grating.
The number of scans per step of the charged particle beam is a value after the decimal point with respect to a value obtained by adding or subtracting a predetermined real number having a value below the decimal point for each step to a predetermined real number. A method for producing a blazed diffraction grating, wherein the value is converted into an integer by rounding down or rounding up , and the increment value or the decrement value is determined not to be constant .   The method for producing a blazed diffraction grating according to claim 1, wherein a distance between steps of the charged particle beam is proportional to a grating interval of the blazed diffraction grating.   The blazed diffraction grating manufacturing method according to claim 1, wherein a distance between steps of the charged particle beam is constant.   The method for producing a blazed diffraction grating according to claim 1, wherein a distance between steps of the charged particle beam becomes narrower toward a deepest part of the blazed diffraction grating.   The method for producing a blazed diffraction grating according to claim 1, wherein a distance between steps of the charged particle beam becomes narrower toward a shallowest portion of the blazed diffraction grating.   The blazed diffraction grating manufacturing method according to claim 1, wherein a distance between steps of the charged particle beam varies locally. The method for producing a blazed diffraction grating according to any one of claims 1 to 6, wherein the number of steps for each lattice line of the charged particle beam with respect to the lattice spacing of the blazed diffraction grating is 3 or more. .
Optical sheet.

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