JP2021185623A - Charged particle beam exposure mask and manufacturing method thereof - Google Patents

Abstract

To provide a high-quality charged particle beam exposure mask and a manufacturing method for manufacturing the exposure mask.SOLUTION: A charged particle beam exposure mask comprises: a frame-shaped support section supporting a thin plate section including a first face and a second face opposed to the first face from the side of the first face; and a reinforcement section reinforcing the thin plate section. An opening through which a charged particle beam is passable, is formed in a pattern region included in the thin plate section. The reinforcement section includes a first reinforcement part and a second reinforcement part. The first reinforcement part includes: a first minimum width portion continued to a non-transmittable portion; and a first maximum width portion positioned farthest from the thin plate section. The second reinforcement part includes: a second minimum width portion continued to the first maximum width portion; and a second maximum width portion positioned farthest from the thin plate section. A width of the first reinforcement part is increased gradually from the first minimum width portion to the first maximum width portion, and a width of the second reinforcement part is increased gradually from the second minimum width portion to the second maximum width portion. A width of the first minimum width portion is greater than a width of the second minimum width portion, and a width of the first maximum width portion is greater than a width of the second maximum width portion.SELECTED DRAWING: Figure 3

Description

The present disclosure relates to a mask for exposure to charged particle beams and a method for manufacturing the mask for exposure to charged particle beams.

With the miniaturization and high integration of integrated circuits such as semiconductor devices, a charged particle beam lithography method using a charged particle beam such as an electron beam or an ion beam is used for pattern formation instead of the photolithography method. The charged particle beam lithography method includes a method of directly drawing a charged particle beam on an exposed object using a charged particle beam exposure device and a stencil-type charged particle beam exposure between the charged particle beam exposure device and the exposed object. There is a method of exposing a pattern by interposing a mask.

As a stencil-type mask for exposure to charged particle beams, a mask having an opening (sometimes called a transmission portion) in a thin plate portion is on the market. The thickness of the thin plate portion constituting the stencil type charged particle beam exposure mask is generally about several μm, and the mechanical strength is low. Therefore, there is a problem that the thin plate portion is deformed due to the influence of stress in the manufacturing process, the strain of the substrate, or the influence of the water pressure at the time of cleaning. Further, especially in the case of a thin plate portion having a plurality of openings, the problem of deformation becomes remarkable. Therefore, in recent years, a frame-shaped support portion is provided below the outer edge of one surface of the thin plate portion, and the support portion of the thin plate portion is reinforced between the plurality of openings on the one surface, which is continuous with the support portion. A mask for exposure to a charged particle beam having a structure provided with a reinforcing portion has been developed.

Japanese Patent No. 4570913

In the process of manufacturing a mask for charged particle beam exposure, for example, by using an electron beam lithography method or a photolithography method, a pattern for manufacturing a reinforcing portion is formed on a substrate, or the pattern is etched as a mask. When the reinforcing portion is manufactured, for example, a phenomenon such as an alignment deviation of several μm, a taper angle of the side wall due to etching, and a tilt in which the etching direction bends from a desired direction may occur. In particular, when the pitch of openings (distance between the centers of adjacent openings) becomes short, these phenomena can occur remarkably. Due to the occurrence of these phenomena, the reinforcing portion may be deformed such as tilted or distorted, and the reinforcing portion cannot be formed accurately according to the intended design. As a result, the charged particle beam that has passed through the opening is shielded by the reinforcing portion, and the desired pattern cannot be formed accurately.

The present disclosure has been made in view of the above circumstances, and an object of the present disclosure is to provide a high-quality charged particle beam exposure mask and a manufacturing method for manufacturing the exposure mask.

As one embodiment of the present disclosure, a thin plate portion having a first surface and a second surface facing the first surface, a frame-shaped support portion that directs the thin plate portion from the first surface side, and the thin plate portion. A charged particle beam exposure mask provided with a reinforcing portion that is continuous with the first surface and the inner side surface of the support portion and reinforces the thin plate portion, and is the thin plate in a plan view of the charged particle beam exposure mask. A plurality of openings through which charged particle beams can pass are formed in a pattern region surrounded by a region supported by the support portion among the portions, and the reinforcing portion is the charged particles in the pattern region. The non-transmissive portion where the wire cannot be transmitted is continuous with the charged particle beam penetrating the opening so as not to shield the charged particle beam, and the first reinforcing portion continuous with the non-transmissive portion and the first reinforcing portion. It has a continuous second reinforcing portion, and the first reinforcing portion has a first minimum width portion continuous with the non-transmissive portion and a first of the first reinforcing portions located farthest from the thin plate portion. The second reinforcing portion includes the maximum width portion, the second minimum width portion continuous with the first maximum width portion, and the second maximum width of the second reinforcing portion located farthest from the thin plate portion. In the cross-sectional view of the charged particle beam exposure mask including the portion, the width of the first reinforcing portion gradually increases from the first minimum width portion to the first maximum width portion, and the second the width of the reinforcing portion is gradually increased from the second minimum width portion toward the second maximum width portion, in a cross-sectional view of the charged particle beam exposure mask, the width S ₄ of the first minimum width portion the larger than the second width S ₇ of the minimum width portion, the width S ₁ of the first maximum width portion, the second charged particle beam exposure mask larger than the width S ₅ of the maximum width portion is provided ..

In the cross-sectional view of the charged particle beam exposure mask placed on the horizontal plane, the angle formed by the side wall surface of the first reinforcing portion with respect to the horizontal plane is equal to or larger than the angle formed by the side wall surface of the second reinforcing portion with respect to the horizontal plane. The height of the first reinforcing portion may be equal to or higher than the height of the second reinforcing portion, and the support portion includes the first end portion continuous with the first surface of the thin plate portion and the support portion. The second end portion facing the first end portion may be provided, and the second end portion of the support portion and the second maximum width portion may be substantially located on the same surface. ..

As one embodiment of the present disclosure, in the method for manufacturing the above-mentioned charged particle beam exposure mask, a substrate having a first main surface and a second main surface facing the first main surface is prepared, and the opening thereof. A step of forming a first concave portion corresponding to the portion on the second main surface side of the substrate, a step of forming a resin layer covering the second main surface on which the first concave portion is formed, and a step of forming the support portion. A step of forming a hard mask pattern including a corresponding first hard mask pattern and a second hard mask pattern corresponding to the second reinforcing portion on the first main surface, and the first step of covering the second hard mask pattern. A step of forming a resist pattern corresponding to one reinforcing portion on the first main surface, a step of etching the first main surface to a predetermined depth of the substrate using the resist pattern as an etching mask, and a step of etching the substrate. After etching the first main surface to the predetermined depth, the step of removing the resist pattern and after the resist pattern is removed, the hard mask pattern is used as an etching mask to etch the first main surface. Provided is a method for manufacturing a mask for charged particle beam exposure, which comprises a step of penetrating the bottom surface of the first recess.

The above substrate is preferably an SOI substrate in which a silicon layer is laminated via a silicon oxide layer.

According to the present disclosure, it is possible to provide a high-quality charged particle beam exposure mask and manufacture the exposure mask.

FIG. 1 is a plan view showing a mask for charged particle beam exposure according to the first embodiment of the present disclosure. FIG. 2A is a cross-sectional view taken along the line AA of the charged particle beam exposure mask shown in FIG. 1, and FIG. 2B is for defining an equation for deriving the height of the reinforcing portion. FIG. 3 is a schematic diagram in which the periphery of the reinforcing portion of the charged particle beam exposure mask shown in FIG. 2A is enlarged and the reinforcing portion is exaggerated. FIG. 3A shares a plan view showing the charged particle beam exposure mask shown in FIG. 1, and the cross-sectional view shape of the charged particle beam exposure mask shown in FIG. 1 in line AA is the same as that of FIG. It is a cross-sectional view which shows the mask for charged particle beam exposure which is different and concerns on the 2nd Embodiment of this disclosure, and FIG. In this figure, the area around the first reinforcing portion and the second reinforcing portion of the charged particle beam exposure mask shown in FIG. 3A is enlarged, and the first reinforcing portion and the second reinforcing portion are exaggerated. It is a schematic diagram drawn by. FIG. 4 is a process diagram for explaining a method for manufacturing a mask for charged particle beam exposure according to the first embodiment of the present disclosure. FIG. 5 is a process diagram following FIG. 4 for explaining a method for manufacturing a mask for charged particle beam exposure according to the first embodiment of the present disclosure. FIG. 6 is a process diagram following FIG. 5 for explaining a method for manufacturing a mask for charged particle beam exposure according to the first embodiment of the present disclosure. FIG. 7 is a process diagram for explaining a method for manufacturing a mask for charged particle beam exposure according to the second embodiment of the present disclosure. FIG. 8 is a process diagram following FIG. 7 for explaining a method for manufacturing a mask for charged particle beam exposure according to the second embodiment of the present disclosure.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. It should be noted that the drawings are schematic or conceptual, and the dimensions of each member, the ratio of the sizes between the members, etc. are not necessarily the same as the actual ones, and may represent the same members, etc. However, the dimensions and ratios may differ from each other depending on the drawing. Further, in the drawings attached to the present specification, in order to facilitate understanding, the shape, scale, aspect ratio, etc. of each part may be changed or exaggerated from the actual product.

In addition, the numerical range represented by using "~" in this specification etc. means a range including each of the numerical values described before and after "~" as a lower limit value and an upper limit value. Further, in the present specification and the like, terms such as "film", "sheet" and "board" are not distinguished from each other based on the difference in designation. For example, "board" is a concept that includes members that can be generally called "sheet" or "film".

[Mask for charged particle beam exposure]
[First Embodiment]
An embodiment of the charged particle beam exposure mask of the present disclosure will be described.
FIG. 1 is a plan view showing a charged particle beam exposure mask according to the first embodiment, and FIG. 2A is a cross-sectional view taken along the line AA of the charged particle beam exposure mask shown in FIG. Yes, FIG. 2B is a diagram for defining an equation for deriving the height of the reinforcing portion, and the circumference of the reinforcing portion of the charged particle beam exposure mask shown in FIG. 2A is enlarged. It is a schematic diagram which exaggerated the said reinforcement part. As shown in FIGS. 1 and 2A, the charged particle beam exposure mask 1 has a substantially rectangular shape in a plan view, and includes a thin plate portion 10, a support portion 12, and a reinforcing portion 13. The charged particle beam exposure mask 1 according to the first embodiment has a substantially rectangular shape in a plan view, but is not limited to this, and for example, even if it has a substantially circular shape in a plan view, it has a pentagonal shape or a hexagonal shape. , It may be a polygonal shape such as an octagon. When the charged particle beam exposure mask 1 is used as, for example, a stencil mask or an aperture, the shape can be appropriately set according to the shape of a jig or holder for setting the mask 1.

The thin plate portion 10 has a first surface B and a second surface F facing the first surface B (FIG. 2A). A support portion 12 is provided on the first surface B side of the thin plate portion 10, and the thin plate portion 10 is supported on the first surface B side thereof by the support portion 12. Further, on the first surface B side of the thin plate portion 10, a reinforcing portion 13 continuous with the first surface B and the inner side surface 12i of the support portion 12 is provided, and the thin plate portion 10 is reinforced by the reinforcing portion 13. ..

The thin plate portion 10 shown in FIG. 1 has a substantially rectangular shape in a plan view, and has a pattern region P surrounded by a broken line and a non-pattern region 10b surrounding the outside of the pattern region P. The pattern region P is composed of a plurality of openings 11 through which the charged particle beam can pass, and a non-transmissive portion 10a through which the charged particle beam cannot pass. The pattern region P is a region reinforced by the reinforcing portion 13, and the non-pattern region 10b is a region supported by the support portion 12. The shape of the thin plate portion 10 can be appropriately set according to the plan view shape of the charged particle beam exposure mask 1.

The opening 11 is a through hole that penetrates the thin plate portion 10 in the thickness direction, and the opening 11 forms a charged particle beam emitted from a charged particle beam drawing device into a predetermined rectangle (square in the illustrated example). Can be used as a molded aperture. The non-transmissive portion 10a has a planar visual grid shape, and is located in a portion (non-transmissive portion 10a) of the pattern region P where the opening 11 is not formed so as to surround the opening 11. Further, the non-transmissive portion 10a is continuous with the non-pattern region 10b. In FIG. 1, 12 openings 11 are arranged in a pattern region P in a grid pattern of 3 rows × 4 columns, but the present invention is not limited to this embodiment, and the opening shape of the openings 11 is not limited to this. , Number, arrangement, dimensions and the like can be appropriately set according to the purpose of use of the charged particle beam exposure mask 1.

The thickness of the thin plate portion 10 is 0.2 μm to 30 μm, preferably 1 μm to 10 μm, and more preferably 1 μm to 5 μm. Further, the material of the thin plate portion 10 is single crystal silicon (Si) when an SOI (Silicon On Insulator) substrate is used as the substrate for manufacturing the mask 1 for charged particle beam exposure, but it is appropriate depending on the substrate to be used. Can be set. For example, as the substrate for manufacturing the mask 1 for charged particle beam exposure, in addition to the SOI substrate, a silicon substrate; a silicon compound substrate such as silicon nitride, silicon carbide, silicon oxide, etc.; A laminated body or the like in which a plurality of layers made of the selected material are laminated can be used. Therefore, the material and the thickness of the thin plate portion 10 can be appropriately set according to the substrate used as the manufacturing substrate of the charged particle beam exposure mask 1. For example, when the material of the thin plate portion 10 is single crystal silicon, the thickness of the thin plate portion 10 is, for example, 1 μm to 10 μm, and when the material of the thin plate portion 12 is silicon nitride, the thickness of the thin plate portion 10 is. For example, it is 0.2 μm to 2 μm, and in the case of silicon carbide, the thickness of the thin plate portion 10 is, for example, 1 μm to 30 μm.

The support portion 12 has a planar viewing frame shape and is provided in the non-patterned region 10b on the first surface B side of the thin plate portion 10 to support the thin plate portion 10 (non-patterned region 10b). Further, the support portion 12 has a laminated structure of the upper support portion 12h and the lower support portion 12g. When an SOI substrate is used as a substrate for manufacturing the charged particle beam exposure mask 1, the material of the upper support portion 12h is silicon oxide (SiO ₂ , embedded silicon oxide layer; also referred to as a box layer), and the material of the lower support portion 12g. Is single crystal silicon (Si). That is, in the support portion 12, the upper support portion 12h made of silicon oxide is fixed to the outer peripheral edge of the first surface B of the thin plate portion 10. As a result, the support portion 12 supports the thin plate portion 10.

As described above, as the substrate for manufacturing the mask 1 for charged particle beam exposure, in addition to the SOI substrate, a silicon substrate; a silicon compound substrate such as silicon nitride, silicon carbide, silicon oxide, etc .; a desired material including these substrate materials. A laminated substrate or the like in which a plurality of layers made of a material selected from the above are laminated can be used. When the laminated substrate is used as a substrate for manufacturing the mask 1 for charged particle beam exposure, the laminated substrate has, for example, a layer for forming a thin plate portion 10 and a layer for forming a support portion 12. Any material may be used as long as it has etching selectivity in each layer. That is, as long as the thin plate portion 10 is a self-supporting thin film (membrane) and can maintain the state of having the opening 11, the support portion 12 does not have a member corresponding to the upper support portion 12h. May be good.

In the first embodiment, the height y of the support portion 12 is not particularly limited, and can be set in consideration of the material of the support portion 12, the dimensions of the frame shape in a plan view, and the like. The height y of the support portion 12 can be appropriately set in the range of, for example, 200 μm to 2000 μm, preferably 300 μm to 725 μm.

The reinforcing portion 13 is continuous with the non-transmissive portion 10a on the first surface B of the thin plate portion 10, whereby the thin plate portion 10 (pattern region P) can be reinforced. In the first embodiment, the reinforcing portion 13 is arranged in a plan view grid pattern (or at a portion separated from the peripheral edge of each opening 11) so as to be sandwiched between adjacent openings 11 in the pattern region P (FIG. 1 is shown by a dotted line), but the present invention is not limited to this aspect. The form of the reinforcing portion 13 can be appropriately set according to the number of openings 11 formed in the pattern region P and the arrangement configuration.

In the charged particle beam exposure mask 1 shown in FIGS. 1 and 2A, the reinforcing portion 13 is continuous with the support portion 12 and the thin plate portion 10 (first surface B). As a result, even if stress or the like acts on the charged particle beam exposure mask 1, distortion is suppressed in the charged particle beam exposure mask 1, and deformation of the thin plate portion 10 and damage to the opening 11 are prevented. be able to. Further, the reinforcing portion 13 also functions as a heat radiating member that releases the heat generated by the collision of the charged particle beam with the thin plate portion 10 to the outside.

Further, similarly to the support portion 12, the reinforcing portion 13 has a laminated structure of the upper reinforcing portion 13h and the lower reinforcing portion 13g. Further, as in the case of the support portion 12, when the SOI substrate is used as the substrate for manufacturing the mask 1 for charged particle beam exposure, the material of the upper reinforcing portion 13h is silicon oxide (SiO ₂ ), and the material of the lower reinforcing portion 13g is single. It becomes crystalline silicon (Si). When a substrate other than the SOI substrate is used as the manufacturing substrate of the charged particle beam exposure mask 1, the materials of the upper reinforcing portion 13h and the lower reinforcing portion 13g are the same as those of the supporting portion 12 described above, and the manufacturing substrate is the same. The material can be made according to the type of the manufacturing substrate, and the structure of the reinforcing portion 13 can be made according to the type of the manufacturing substrate. For example, the reinforcing portion 13 may not have the upper reinforcing portion 13h.

In the first embodiment, the reinforcing portion 13 is continuous with the non-transmissive portion 10a of the thin plate portion 10 so as not to shield the charged particle beam passing through the opening 11, and the height Z ₀ of the reinforcing portion 13g is , Expressed by the following equations (1) to (5). Here, the reinforcing portion 13 g of the charged particle beam exposure mask 1 shown in FIG. 2B is formed in a tapered shape, and the angle formed by the upper surface 13 gt facing the thin plate portion 10 side and the side wall surface 13 gs is the desired angle. It is assumed that _{θ 1} is larger than 90 ° of. _{The angle θ 1} in the first embodiment is assumed to have a size of about 91 ° to 95 °, which is slightly larger than 90 °, but as long as the charged particle beam passing through the opening 11 is not shielded. It is not limited to this. If the angle θ ₁ and the angle θ ₁ ′ facing the angle θ 1 ′ are not the same angle, the width S ₂ may be derived based on the average angle θ _{AVG between the angle θ 1} and the angle θ _{1 ′.} It goes without saying that FIG. 2B is an exaggerated drawing of the reinforcing portion 13g so that the angled state can be easily recognized, and the angle θ ₁ does not represent the actual angle. In FIG. 2B, the width of the non-transparent portion 10a is S ₀ , the width of the reinforcing portion 13g located between the opening 11A adjacent to the reinforcing portion 13g and the opening 11B is S ₁ , and the thin plate portion 10 is formed. Located on the nearest side, the end 13gtA (or the end 13gtB located on the opening 11B side) located on the opening 11A side of the upper surface 13gt of the reinforcing portion 13g and the opening 11A side of the bottom surface 13gu of the reinforcing portion 13g. the width between the end 13GuA (or end 13guB positioned in the opening 11B side) and _{S 2,} and one end 10aA of the opening 11A side of the non-transparent portion 10a (or the opening 11B side of the one end 10aB) to the width between the end 13GuA (or end 13GuB) and _{S 3.} The width S ₂ occurs when the taper angle θ ₁ is attached to the reinforcing portion 13g, and at this time, the width of the bottom surface 13gu is larger than the width of the upper surface 13gt of the reinforcing portion 13g. Further, the maximum width of the reinforcing portion 13g is smaller than the width of the non-transmissive portion 10. Further, S ₄ represents the width of the upper surface 13 gt of the reinforcing portion 13 g, and this width S ₄ is obtained by subtracting twice the above width S _{2 from the width S 1} of the bottom surface 13 gu of the reinforcing portion 13 g. In the embodiment of 1, any value exceeding 0 may be used.
Z ₀ = S ₂ / tan (θ _{1 −} π / 2) ・ ・ ・ (1)
_{S 2 <S 1/2 ···} (2)
S ₁ = S ₀ -2S ₃ ... (3)
S ₃ > 0 ... (4)
90 ° <θ ₁ <180 ° ・ ・ ・ (5)

_{By setting the height Z 0} of the reinforcing portion 13 to the height represented by the equations (1) to (5), the charged particle beam passing through the opening 11 is shielded by, for example, the deformed reinforcing portion 13. Since the object to be exposed is irradiated without any need, the desired pattern can be formed with high accuracy. The height Z ₀ of the reinforcing portion 13 is not particularly limited as long as the reinforcing portion 13 can exert sufficient strength to reinforce the thin plate portion 10, and is, for example, 5 μm to 300 μm, preferably 5 μm to 150 μm. More preferably, it can be set to 5 μm to 50 μm.

In the charged particle beam exposure mask 1 according to the first embodiment, the outer surface of the thin plate portion 12 and the outer surface of the support portion 13 are configured to be substantially flush with each other, but the present invention is limited to this aspect. It's not a thing. The charged particle beam exposure mask 1 is formed by the outer surface of the thin plate portion 12 entering into the inside of the outer surface of the support portion 13, and the corner portion and the support portion 13 forming a part of the outer edge of the thin plate portion 12 are formed. It may have a stepped structure with corners forming a part of the outer edge. As a result, it is possible to suppress the application of unnecessary force to the thin plate portion 12 from the outside when the charged particle beam exposure mask 1 is conveyed, the handling becomes easy, and the multi-faceted chip is divided. It is possible to suppress the application of an unnecessary force to the thin plate portion 12 at the time of the operation.

[Second Embodiment]
FIG. 3A shares a plan view showing the charged particle beam exposure mask shown in FIG. 1, and the cross-sectional view shape of the charged particle beam exposure mask shown in FIG. 1 in line AA is the same as that of FIG. FIG. 3B is a cross-sectional view showing a different charged particle beam exposure mask 1 according to the second embodiment, and FIG. 3B is for defining an equation for deriving the heights of the first reinforcing portion and the second reinforcing portion. In the figure of FIG. 3, the circumference of the first reinforcing portion and the second reinforcing portion of the charged particle beam exposure mask shown in FIG. 3A is enlarged, and the first reinforcing portion and the second reinforcing portion are exaggerated. It is a schematic diagram drawn. The charged particle beam exposure mask 1 according to the second embodiment is a charged particle according to the first embodiment in that the lower reinforcing portion 13g of the reinforcing portion 13 includes a first reinforcing portion 131 g and a second reinforcing portion 132 g. It is different from the line exposure mask 1. Therefore, in the second embodiment, substantially the same configurations as those in the first embodiment are designated by the same reference numerals, detailed description thereof will be omitted, and the second reinforcing portion 132 g will be mainly described.

As shown in FIG. 3, the second reinforcing portion 132 g has a substantially rectangular cross-sectional view, and the first end portion 132 gt thereof is attached to the bottom end portion 131 gu (lower end portion in the drawing) of the first reinforcing portion 131 g. Continuous. The first reinforcing portion 131g is continuous with the non-transmissive portion 10a on the first surface B of the thin plate portion 10 via the upper reinforcing portion 13h. Further, the second end portion 132gu facing the first end portion 132gt of the second reinforcing portion 132g and the second end portion 12u of the support portion 12 are substantially located on the same surface. The first end portion 12t facing the second end portion 12u of the support portion 12 is continuous with the first surface B of the thin plate portion 10. By locating the second end portion 132gu of the second reinforcing portion 132g and the second end portion 12u of the support portion 12 on the same surface, the height of the first reinforcing portion 131g in the second embodiment is lowered. However, the thin plate portion 10 can be sufficiently reinforced by the reinforcing portion 13.

Further, in the present embodiment, _{it is preferable that the width S 5 of the second reinforcing portion 132 g is smaller than the width S 1} of the first reinforcing portion 131 g, and the above formulas (1) to (5) and the following formulas (6) to (6) to ( It is represented by 13). Here, the first reinforcing portion 131 g of the charged particle beam exposure mask 1 shown in FIG. 3 (B) is formed in a tapered shape, and the angle formed by the upper surface 131 gt facing the thin plate portion 10 side and the side wall surface 131 gs is set. It is assumed that _{θ 1} is larger than the expected 90 °. _{The angle θ 1} in the second embodiment is assumed to have a size of about 91 ° to 95 °, which is slightly larger than 90 °, but as long as the charged particle beam passing through the opening 11 is not shielded. It is not limited to this. Further, the second reinforcing portion 132 g of the charged particle beam exposure mask 1 shown in FIG. 3 (B) is formed in a tapered shape, and the angle formed by the first end portion 132 gt and the side wall surface 132 gs is the desired 90 °. It is assumed that the value is greater than θ _{2. The angle θ 2} in the second embodiment is assumed to have a size of about 91 ° to 95 °, which is slightly larger than 90 °, but as long as the charged particle beam passing through the opening 11 is not shielded. It is not limited to this. FIG. 3B is an exaggerated drawing of the first reinforcing portion 131 g and the second reinforcing portion 132 g so that the angled state can be easily recognized, and the angles θ ₁ and θ ₂ show the actual angle. It goes without saying that it is not a representation. In FIG. 3B, the width of the non-transmissive portion 10a is S _0, and the width of the second reinforcing portion 132g located between the opening 11A adjacent to the second reinforcing portion 132g and the opening 11B is S ₅ . one end 132guA second end 132gu positioned in the opening 11A side, a width between the end 132gtA the first end portion 132gt positioned in the opening 11A side is _{S 6,} the upper surface of the first reinforcement part 131 g 131Gt The width of _{the second reinforcing portion 132 g is S 4,} and the width of the second end portion 132 g of the second reinforcing portion 132 g is S ₇ . The width S ₆ occurs when the taper angle θ ₂ is attached to the second reinforcing portion 132 g, and at this time, the width of the second end portion 132 gu is larger than the width of the first end portion 132 gt of the second reinforcing portion 132 g. It becomes a thing. Further, the width of the second end portion 132gu of the second reinforcing portion 132g is smaller than the width of the bottom surface of the first reinforcing portion 131g. _{In the second embodiment, the angles θ 1} and θ ₂ are the following equations (12) as long as the charged particle beam transmitted through the opening 11 is not shielded by the first reinforcing portion 131 g and the second reinforcing portion 132 g. _{), And the heights Z 0} and Z _{1 of} the first reinforcing portion 131 g preferably satisfy the condition represented by the following formula (13).
S ₅ > 2Z ₁・ tan (θ _2- π / 2) ・ ・ ・ (6)
S ₁ > 2Z ₀ · tan (θ _{1 −} π / 2) ・ ・ ・ (7)
S ₁ > S ₅ ... (8)
S ₄ > 0 ... (9)
S ₇ > 0 ... (10)
90 ° <θ ₂ <180 ° ・ ・ ・ (11)
θ ₁ ≧ θ ₂ ... (12)
Z ₁ ≧ Z ₀ ... (13)

_{Charged particles that have passed through the opening 11 by making the width S 5} of the second reinforcing portion 132 g _{smaller than the width S 1} of the first reinforcing portion 131 g, preferably by setting the width represented by the equation (6). Since the line is applied to the exposed object without being shielded by the second reinforcing portion 132 g, the desired pattern can be formed with high accuracy. Further, in order not to shield the charged particle beam transmitted through the opening 11, in the charged particle beam exposure mask 1 according to the first embodiment, the height of the reinforcing portion 13, specifically, the lower reinforcing portion. It is conceivable to make the height of 13 g as low as possible, but if the height of the lower reinforcing portion 13 g is made too low, the reinforcing performance of the reinforcing portion 13 with respect to the thin plate portion 10 may deteriorate. Therefore, in the charged particle beam exposure mask 1 according to the second embodiment, it is particularly significant that the reinforcing portion 13 has the second reinforcing portion 132 g. The width of the second reinforcing portion 132g is particularly limited as long as the charged particle beam transmitted through the opening 11 is not shielded and sufficient strength can be secured enough to reinforce the thin plate portion 10. Instead, for example, it can be appropriately set within the range of 1 μm to 400 μm.

As described above, in the charged particle beam exposure mask 1 according to the second embodiment, the height of the first reinforcing portion 131 g is set from the height of the lower reinforcing portion 13 g (see FIG. 2) in the first embodiment. Even if it is lowered, the thin plate portion 10 can be sufficiently reinforced. The height of such a first reinforcing portion 131 g can be appropriately set within the range of, for example, 5 μm to 150 μm.

[Manufacturing method of mask for charged particle beam exposure]
[First Embodiment]
Next, an embodiment of a method for manufacturing a mask for charged particle beam exposure will be described.
4 to 6 are process diagrams for explaining a method for manufacturing a charged particle beam exposure mask according to the first embodiment, and are charged particles according to the first embodiment shown in FIGS. 1 and 2. A method of manufacturing the line exposure mask 1 will be described as an example.

As the substrate 30 for forming the mask for charged particle beam exposure, an SOI substrate in which a support substrate 70 mainly made of silicon single crystal, a box layer 60, and a single crystal silicon layer 50 are laminated in this order is used. prepare. The box layer 60 contains silicon oxide, and the thickness of the single crystal silicon layer 50 is 1 μm to 10 μm. Then, the main surface 30 m of the substrate 30 (here, the upper surface of the single crystal silicon layer 50 corresponds to the second surface F of the thin plate portion 10 shown in FIG. 2), and the main surface 30s facing the main surface 30s (here). Then, a hard mask material layer is formed on the lower surface of the support substrate 70). That is, the hard mask material layer 80a is formed on the single crystal silicon layer 50 constituting the substrate 30, and the hard mask material layer 80b is formed on the support substrate 53a (FIG. 4A).

The thickness of the substrate 30 is not particularly limited and may be, for example, a thickness in the range of 200 μm to 2000 μm, but the thickness of the substrate 30 is preferably 300 μm to 725 μm in consideration of the processability of the substrate. ..

Examples of the material constituting the hard mask material layers 80a and 80b include silicon oxide; a metal material such as chromium and aluminum, and the box layer 60 is a material that can be etched by the same etchant as the etchant. Is preferable. In the following description, a process using silicon oxide contained in the box layer 60 as the hard mask material layers 80a and 80b will be described.

Next, a resist pattern 90 is formed on the hard mask material layer 80a (FIG. 4B). The resist pattern 90 has a plurality of openings 91 in the region P'corresponding to the pattern region P shown in FIG. The resist pattern 90 can be formed by an electron beam lithography method using an electron beam sensitive resist or by a photolithography method using a photosensitive resist. Further, the resist pattern 90 may be formed by combining the electron beam lithography method and the photolithography method.

Next, the hard mask material layer 80a is etched using the resist pattern 90 as a mask to form the hard mask pattern 80'a, and the single crystal silicon layer 50 is etched using the hard mask pattern 80'a as an etching mask (FIG. 4 (FIG. 4). C)). In this etching, the box layer 60 acts as an etching stopper, and a recess 51 having a bottom surface of the box layer 60 is formed in the single crystal silicon layer 50. As a result, the depth of the recess 51 corresponds to the thickness of the single crystal silicon layer 50 and is within the range of 1 μm to 10 μm. Therefore, in the subsequent step, the depth of the opening 11 formed at the stage where the support substrate 70 is etched, the exposed box layer 60 is removed, and the bottom surface of the recess 51 penetrates the support substrate 70 side is 1 μm. The desired depth is within the range of 10 μm. In addition, in FIG. 4C, the region sandwiched between the recesses 51 adjacent to each other, that is, the non-opening region 50a in which the recess 51 is not formed in the region P'is formed in the non-transmissive portion 10a shown in FIGS. 1 and 2. The corresponding area. Further, the outer peripheral region 50b of the region P'is a region corresponding to the non-patterned region 10b shown in FIGS. 1 and 2.

The hard mask material layer 80a can be etched by wet etching or dry etching. When the hard mask material layer 80a made of silicon oxide is wet-etched, hydrofluoric acid, a chemical solution containing hydrofluoric acid, or the like can be used as the etching solution as an etchant. On the other hand, when the hard mask material layer 80a made of silicon oxide is dry-etched, trifluoromethane (CHF ₃ ) gas, ethane hexafluoroethane (C ₂ F ₆ ) gas and the like can be used as the etching gas. According to the dry etching having anisotropy, the hard mask pattern 80'a having a size almost as designed can be formed.

Further, the etching of the single crystal silicon layer 50 can also be performed by wet etching or dry etching. When the single crystal silicon layer 50 is wet-etched, a KOH aqueous solution, ethylenediamine / pyrocatechol (EDP), tetramethylammonium hydroxide (TMAH) or the like can be used as the etching solution. On the other hand, when the single crystal silicon layer 50 is dry-etched, carbon tetrafluoride (CF ₄ ), carbon tetrafluoride (C ₄ F ₈ ), sulfur hexafluoride (SF ₆ ), hydrogen bromide (HBr), etc. are used. It can be used as an etching gas.

Next, a resin layer 100 covering the upper surface (corresponding to the second surface F of the thin plate portion 10) of the single crystal silicon layer 50 in which the recess 51 is formed is formed. Further, similarly to the resist pattern 90 formed on the hard mask material layer 80a, a resist pattern (not shown) is formed on the hard mask material layer 80b, and the hard mask material layer 80b is etched using this resist pattern as a mask to perform a hard mask. A pattern 80'b is formed (FIG. 5 (A)). The hard mask material layer 80b can be etched by wet etching or dry etching in the same manner as the etching of the hard mask material layer 80a.

The resin layer 100 is formed for the purpose of protecting the recess 51 and for suppressing distortion when etching the support substrate 70 in a subsequent step. Therefore, the thickness of the resin layer 100 can be appropriately set in the range of 5 μm to 30 μm. In the illustrated example, such a resin layer 100 is formed over the entire substrate, but it may be formed at least within a range covering the recess 51. As a material constituting the resin layer 100, a known resin material used as a resist or the like can be used, and the resin layer 100 is formed by applying a solution of the resin material by a spin coating method or the like and performing heat treatment. Can be done. The thickness of the resin layer 100 can be controlled by adjusting the viscosity of the solution by adjusting the concentration of the resin material or the additive, and further adjusting the rotation speed of the substrate at the time of applying the solution. If the desired thickness cannot be obtained by applying the solution once, the application and curing of the solution may be repeated a plurality of times until the resin layer has the desired thickness.

The hard mask pattern 80'b has a rectangular opening 85 in a plan view corresponding to the pattern region P (shown by a broken line in FIG. 1) shown in FIGS. 1 and 2. The opening 85 is provided with an opening size and an opening shape suitable for forming the support portion 72g, which will be described later, in consideration of the etching method, etching conditions, the material of the substrate 30, and the like.

Next, a resist pattern 110 corresponding to the reinforcing portion 13 is formed on the lower surface 30s of the support substrate 70 corresponding to the opening 85 (pattern region P), and the support substrate 70 is oriented in the arrow E direction with the resist pattern 110 as an etching mask. A plurality of openings 75 facing the recess 51 are formed by dry etching upward to a predetermined depth indicated by (FIG. 5 (B)). The "predetermined depth" for etching the support substrate 70 can be appropriately set to such an extent that the reinforcing portion 13 having _{a height Z 0} represented by the above formulas (1) to (5) can be formed.
The resist pattern 110 can be formed by an electron beam lithography method using an electron beam sensitive resist or by a photolithography method using a photosensitive resist. Further, the resist pattern 110 may be formed by combining the electron beam lithography method and the photolithography method.

After etching the support substrate 70 to the above "predetermined depth", the resin layer 100 and the resist pattern 110 are removed, and the support substrate 70 is moved upward as indicated by the arrow E with the hard mask pattern 80'b as an etching mask. Further dry etching is performed (FIG. 5 (C)). Even in this etching, the box layer 60 acts as an etching stopper. As a result, a frame-shaped support portion 72g is formed at a position corresponding to the non-patterned region 50b of the single crystal silicon layer 50 (lower surface of the box layer 60), and a position corresponding to the region 50a (lower surface of the box layer 60). A lower reinforcing portion 73 g is formed on the surface. The box layer 60 exposed between the support portion 72 g and the lower reinforcing portion 73 g formed by etching the support substrate 70 and between the lower reinforcing portions 73 g is provided in the main surface 30s of the substrate 30 in a subsequent step. By etching from the side, the bottom surface of the recess 51 penetrates to form the opening 11. The support substrate 70 can be etched by wet etching or dry etching in the same manner as the etching of the single crystal silicon layer 50.

The resin layer 100 and the resist pattern 110 may be removed by using an organic solvent, or may be removed by ashing such as oxygen plasma treatment. As the organic solvent, for example, a registry mover can be used. After removing the resin layer 100 and the resist pattern 110 using a registry mover, the exposed hard mask patterns 80'a and 80'b and the organic substances remaining on the surface of the box layer 60 exposed by the formation of the recess 51 are removed. SPM cleaning may be performed to remove. The SPM cleaning is also referred to as a sulfuric acid hydrogen peroxide solution cleaning, and _{examples thereof include an example in which a chemical solution mixed at H 2} O ₂ : H ₂ SO ₄ = 3: 1 is heated to 70 ° C to 80 ° C and used. SPM cleaning is a cleaning method that is effective in removing organic substances by utilizing a strong oxidizing action. After the SPM cleaning, the substrate may be dried by IPA drying. Such removal of the resin layer 100 and the resist pattern 110 may be performed in the same process, or may be performed in different processes.

Next, the box layer 60 is etched from the main surface 30s side of the substrate 30 so that the bottom surface of the recess 51 penetrates to form the opening 11, and then the hard mask pattern 80'a and the hard mask pattern 80'b are removed. As a result, the mask 1 for exposure to charged particle beams is formed (FIG. 6). In the first embodiment, the depth of the opening 51 thus formed corresponds to the thickness of the single crystal silicon layer 52, and is a desired depth within the range of 1 μm to 10 μm. .. The box layer 60 can be etched by wet etching or dry etching in the same manner as the etching of the hard mask material layer 80a. Further, the hard mask pattern 80'a and the hard mask pattern 80'b may be removed at the same time as the etching of the box layer 60. Further, even if the resin layer 100 is removed after the box layer 60 exposed between the support portion 72 g and the lower reinforcing portion 73 g and between the lower reinforcing portions 73 g is etched to form the opening 11. good.

After etching the box layer 60 and removing the hard mask patterns 80'a and 80'b in this way, SPM cleaning, APM cleaning, and hydrofluoric acid (HF) cleaning are performed on the substrate 30. Further, after cleaning the substrate 30, the charged particle beam exposure mask may be dried by IPA drying. Here, the APM washing is also referred to as an ammonia hydrogen peroxide water washing, for example, _{a chemical solution mixed with ammonia (NH 4} OH): H ₂ O ₂ : H ₂ O = 1: 2: 5 at 70 ° C to 80 ° C. An example of heating and using it can be given. APM cleaning is a cleaning method that is effective in removing organic substances and insoluble particles.

In the first embodiment, the resist pattern 110 may be misaligned, or the side wall of the opening 75 formed by dry etching of the support substrate 70 using the resist pattern 110 as an etching mask may be tapered. A lower reinforcing portion 73g having an inclination, distortion, or the like can be formed. However, by dry etching the support substrate 70 using the hard mask pattern 80'b as an etching mask after removing the resist pattern 110, the lower reinforcing portion 73 g is formed at a height lower than the height of the support portion 72 g. As a result, even if the misalignment or taper occurs, it is possible to prevent the charged particle beam passing through the opening 11 from being shielded by the lower reinforcing portion 73g in the manufactured charged particle beam exposure mask 1. can.

Therefore, according to the above-mentioned method for manufacturing a charged particle beam exposure mask in the first embodiment, the charged particle beam transmitted through the opening 11 is not shielded by the lower reinforcing portion 73g, and is exposed to the object to be exposed. A high quality charged particle beam exposure mask 1 that can be irradiated can be manufactured.

In the first embodiment, the SOI substrate is used as the substrate 30, but the substrate is not limited to this, and for example, a silicon substrate; a silicon compound substrate such as silicon nitride, silicon carbide, or silicon oxide; these substrate materials may be used. It is possible to use a laminated substrate or the like in which a plurality of layers made of a material selected from the desired materials to be included are laminated. When the laminated substrate is used as the substrate 30, for example, when the charged particle beam exposure mask 1 shown in FIG. 1 is used, a two-layer structure consisting of a layer to be a thin plate portion 10 and a layer to be a support portion 12 is formed. The laminated substrate may be used as the substrate 30. In this case, the laminated substrate may be one that allows selective etching between the layer to be the thin plate portion 10 and the layer to be the support portion 12, and the layer to be the thin plate portion 10 is the thin plate portion. It suffices as long as the 10 is a thin film (membrane) that can stand on its own to the extent that it can be maintained in a state having the opening 11. Further, the laminated substrate may have a laminated structure of three or more layers in order to provide etching selectivity between the layer to be the thin plate portion 10 and the layer to be the support portion 12. When such a laminated substrate is used, by setting the etching conditions according to the etching selectivity of each layer constituting the laminated substrate, a mask for charged particle beam exposure can be obtained in the same manner as when the above-mentioned SOI substrate is used. Can be manufactured. In the present disclosure, the etching selectivity between different layers and materials means that the etching rate may differ when etching is performed under the same conditions.

[Second Embodiment]
A method for manufacturing a mask for charged particle beam exposure according to the second embodiment will be described. 7 to 8 are process diagrams for explaining the manufacturing method of the charged particle beam exposure mask according to the second embodiment, and are for charged particle beam exposure according to the second embodiment shown in FIG. The method of manufacturing the mask 1 will be described as an example. The method for manufacturing the charged particle beam exposure mask according to the second embodiment is described in FIGS. 5 to 5 among the methods for manufacturing the charged particle beam exposure mask according to the first embodiment shown in FIGS. 4 to 6 described above. It includes a process different from the process shown in FIG. That is, the steps shown in FIGS. 7 to 8 are steps following the steps shown in FIG. Therefore, in the second embodiment, detailed description of the process shown in FIG. 4 will be omitted.

In FIG. 4C, after the recess 51 is formed in the single crystal silicon layer 50, the upper surface of the single crystal silicon layer 50 in which the recess 51 is formed (corresponding to the second surface F of the thin plate portion 10) is covered. The resin layer 100 is formed on the surface. Further, a resist pattern (not shown) having a plurality of openings is formed on the hard mask material layer 80b, and the hard mask material layer 80b is etched using this resist pattern as an etching mask to form a hard mask pattern 80 corresponding to the support portion 12. A corresponding pattern 81b (second hard mask pattern) corresponding to the'b (first hard mask pattern) and the second reinforcing portion 132 g is formed (FIG. 7 (A)). In the second embodiment, the width of the resist pattern as the equation (1) to (5) and the first reinforcing portion 131g of the width S ₁ represented by the above formula (7) is formed is set, the width of the corresponding pattern 81b is set such that the second reinforcing portion 132g of the width _{S 5} represented by the formula (1) to (13) are formed.
The hard mask material layer 80b can be etched by wet etching or dry etching. In the present embodiment, in addition to the hard mask pattern 80'b shown in FIG. 7A, a corresponding pattern 81b is formed, which is the same as the method for manufacturing a charged particle beam exposure mask according to the first embodiment. Different (see FIG. 5 (A)).

The resin layer 100 is formed for the purpose of protecting the recess 51 and for suppressing distortion when etching the support substrate 70 in a subsequent step. Therefore, the thickness of the resin layer 100 can be appropriately set in the range of 5 μm to 30 μm. In the illustrated example, such a resin layer 100 is formed over the entire substrate, but it may be formed at least within a range covering the recess 51. As a material constituting the resin layer 100, a known resin material used as a resist or the like can be used, and the resin layer 100 is formed by applying a solution of the resin material by a spin coating method or the like and performing heat treatment. Can be done. The thickness of the resin layer 100 can be controlled by adjusting the viscosity of the solution by adjusting the concentration of the resin material or the additive, and further adjusting the rotation speed of the substrate at the time of applying the solution. If the desired thickness cannot be obtained by applying the solution once, the application and curing of the solution may be repeated a plurality of times until the resin layer has the desired thickness.

In the present embodiment, the hard mask pattern 80'b has an opening 85 having a substantially rectangular shape in a plan view corresponding to the pattern region P (shown by a broken line in FIG. 1) shown in FIGS. 1 and 3. A plurality of corresponding patterns 81b are located in 85. The opening 85 has an opening size and an opening shape suitable for forming a support portion 72g (see FIG. 8), which will be described later, in consideration of the etching method, etching conditions, the material of the substrate 30, and the like.

Next, a resist pattern 110 corresponding to the first reinforcing portion 731g (see FIG. 7C) covering the lower surface and the side surface of the corresponding pattern 81b is formed on the lower surface 30s of the support substrate 70, and this resist pattern 110 is used as an etching mask. The support substrate 70 is etched upward to a predetermined depth indicated by the arrow E direction to form a plurality of openings 75 (FIG. 7 (B)). The resist pattern 110 can be formed by an electron beam lithography method using an electron beam sensitive resist or by a photolithography method using a photosensitive resist. Further, the resist pattern 110 can be formed by combining the electron beam lithography method and the photolithography method. The above-mentioned "predetermined depth" is a depth appropriately set according to the height of the first reinforcing portion 731 g. The deeper the predetermined depth, the higher the height of the first reinforcing portion 731g formed, and the shallower the predetermined depth, the lower the height of the first reinforcing portion 731g formed. _{The "predetermined depth" for etching the support substrate 70 is the first reinforcing portion 731 g having a height Z 0} represented by the above formulas (1) to (5) and the height Z derived from the above formula (6). It can be appropriately set to such an extent that the second reinforcing portion 732 g of _{1 can be formed.}

After etching the support substrate 70 to the above "predetermined depth", the resin layer 100 and the resist pattern 110 are removed, and the hard mask pattern 80'b and the corresponding pattern 81b are used as etching masks for the support substrate 70 (masked with the pattern 81b). (Excluding the portion marked) is further etched upward indicated by the arrow E direction (the arrow e direction on both side surfaces of the second reinforcing portion 732 g) (FIG. 7 (C)). Even in this etching, the box layer 60 acts as an etching stopper. As a result, the frame-shaped support portion 72g is formed at the position corresponding to the non-patterned region 50b of the single crystal silicon layer 50, and the first reinforcing portion 731g is formed at the position corresponding to the region 50a. Further, in the second embodiment, a continuous second reinforcing portion 732 g is formed on the bottom side of the first reinforcing portion 731 g. The box layer 60 exposed between the support portion 72 g and the first reinforcing portion 731 g formed by etching the support substrate 70 and between the first reinforcing portions 731 g is mainly used for the substrate 30 in the subsequent process. By etching from the surface 30s side, the bottom surface of the recess 51 penetrates to form the opening 11. The support substrate 70 can be etched by wet etching or dry etching in the same manner as the etching of the single crystal silicon layer 50.

The resin layer 100 and the resist pattern 110 may be removed by using an organic solvent, or may be removed by ashing such as oxygen plasma treatment. As the organic solvent, for example, a registry mover can be used. After removing the resin layer 100 and the resist pattern 110 using a registry mover, the exposed hard mask patterns 80'a and 80'b and the organic substances remaining on the surface of the box layer 60 exposed by the formation of the recess 51 are removed. SPM cleaning may be performed to remove. SPM cleaning is also referred to as sulfuric acid hydrogen peroxide solution cleaning, and _{examples thereof include an example in which a chemical solution mixed at H 2} O ₂ : H ₂ SO ₄ = 3: 1 is heated to 70 ° C to 80 ° C and used. SPM cleaning is a cleaning method that is effective in removing organic substances by utilizing a strong oxidizing action. After the SPM cleaning, the substrate may be dried by IPA drying. Such removal of the resin layer 100 and the resist pattern 110 may be performed in the same process, or may be performed in different processes.

Next, the box layer 60 is etched from the main surface 30s side of the substrate 30 so that the bottom surface of the recess 51 penetrates to form the opening 11, and then the hard mask pattern 80'a, the hard mask pattern 80'b, and the corresponding pattern. By removing 81b, a charged particle beam exposure mask 1 is formed (FIG. 8). In the present embodiment, the depth of the opening 11 in the charged particle beam exposure mask 1 thus formed corresponds to the thickness of the single crystal silicon layer 50, and is desired within the range of 1 μm to 10 μm. It is the depth of. The box layer 60 can be etched by wet etching or dry etching in the same manner as the etching of the hard mask material layer 80a. At the same time as etching the box layer 60, the hard mask pattern 80'a and the hard mask pattern 80'b may be removed. Further, even if the resin layer 100 is removed after the box layer 60 exposed between the support portion 72 g and the first reinforcing portion 731 g and between the first reinforcing portions 731 g is etched to form the opening portion 11. good.

After etching the box layer 60 in this way and removing the hard mask patterns 80'a and 80'b and the corresponding pattern 81b, SPM cleaning, APM cleaning, and hydrofluoric acid (HF) cleaning are performed on the substrate 30. It will be done. Further, after cleaning the substrate 30, the mask may be dried by IPA drying. Here, the APM washing is also referred to as an ammonia hydrogen peroxide water washing, for example, _{a chemical solution mixed with ammonia (NH 4} OH): H ₂ O ₂ : H ₂ O = 1: 2: 5 at 70 ° C to 80 ° C. An example of heating and using it can be given. APM cleaning is a cleaning method that is effective in removing organic substances and insoluble particles.

In the second embodiment, the resist pattern 110 may be misaligned, or the side wall of the opening 75 formed by dry etching of the support substrate 70 using the resist pattern 110 as an etching mask may be tapered. A first reinforcing portion 731 g and a second reinforcing portion 732 g having an inclination, distortion, or the like can be formed. However, after the resist pattern 110 is removed, the support substrate 70 is dry-etched using the hard mask pattern 80'b and the corresponding pattern 81b as etching masks, so that the first reinforcing portion 731g is formed at a height lower than the height of the support portion 72g. The second reinforcing portion 732 g is formed with a width smaller than that of the first reinforcing portion 731 g. As a result, even if the misalignment or taper occurs, in the manufactured charged particle beam exposure mask 1, the charged particle beam passing through the opening 11 is shielded by the first reinforcing portion 731g and the second reinforcing portion 732g. It is possible to prevent the charge.

From the above, according to the method for manufacturing a charged particle beam exposure mask according to the second embodiment, the charged particle beam transmitted through the opening 11 is shielded by the deformed first reinforcing portion 731g and the second reinforcing portion 732g. It is possible to manufacture a high-quality charged particle beam exposure mask 1 that can irradiate an object to be exposed.

Hereinafter, the present disclosure will be described in more detail with reference to examples, but the present disclosure is not limited to the following examples and the like.

[Example 1]
<Preparation of SOI board>
The substrate 30 is a support substrate 70 (thickness: 400 μm) mainly composed of a silicon single crystal, a box layer 60 (thickness: 1 μm) containing a silicon oxide film, and a single crystal silicon layer 50 (thickness: 2 μm) in this order. A laminated SOI substrate 30 having a diameter of 200 mm was prepared.

<Making a mask for charged particle beam exposure>
Next, using the above-mentioned SOI substrate 30, the hard mask material layer 80a, which is a silicon oxide film having a thickness of 1 μm, is thermally oxidized on the single crystal silicon layer 50 located on one main surface 30 m side of the SOI substrate 30. At the same time as the formation of the hard mask material layer 80a by the method, the hard mask material layer which is a silicon oxide film having a thickness of 1 μm is formed on the support substrate 70 located on the other main surface 30s side of the SOI substrate 30. 80b was formed by a thermal oxidation method (see FIG. 4 (A)).

Next, an electron beam-sensitive resist (Sumiresist NEB series, manufactured by Sumitomo Chemical Co., Ltd.) is applied onto the hard mask material layer 80a (for example, by a spin coating method) to form a resist layer 90. did. Next, the SOI substrate 30 is arranged on the stage in the electron beam drawing apparatus (JBX9500, manufactured by JEOL Ltd.) so that the other main surface 30s side faces the stage, and the SOI substrate 30 is placed on one main surface 30m side. The resist layer 90 formed in the above was irradiated with an electron beam to form a desired pattern latent image. Further, the SOI substrate 30 is arranged so that one main surface 30 m side faces the stage, and the resist layer formed in the same manner as above on the other main surface 30s side of the SOI substrate 30 is also irradiated with an electron beam as desired. Pattern latent image was formed.

Next, the resist layer 90 on one main surface 30 m side of the SOI substrate 30 is developed, and a plurality of rectangular recesses 91 (10 μm × 30 μm) arranged so as to form a grid in 4 columns × 3 rows. A resist pattern containing the above was formed. Using this resist pattern as an etching mask, the hard mask material layer 80a was etched by _{reactive ion etching (CHF 3} : 25 sccm, SF _{6: 5 sccm) using a fluorine-based gas to form a hard mask pattern 80'a.}

Next, using this hard mask pattern 80'a as an etching mask, the single crystal silicon layer 50 is etched by _{reactive ion etching (O 2} : 5 sccm, CHF _{3: 45 sccm) using a fluorine-based gas to obtain single crystal silicon.} A plurality of recesses 51 were formed in the region corresponding to the pattern region P'in the layer 50.
Next, a solution of the resin material was applied onto the single crystal silicon layer 50 so as to cover the plurality of recesses 51 by a spin coating method to form a resin layer 100 (thickness: 15 μm).

Next, a resist layer was formed on the other main surface 30s side of the SOI substrate 30, and the resist layer was exposed and developed to form a resist pattern having an opening (300 mm × 300 mm). Using this rest pattern as an etching mask, the other main surface of the SOI substrate 30 is subjected to reactive ion etching using a fluorine-based gas, as in the case of etching the hard mask material layer 80a on one main surface 30 m side of the SOI substrate 30. The hard mask material layer 80b on the surface 30s side was etched to form a hard mask pattern 80'b.

Next, a photoresist (thickness: 20 μm) was applied to the lower surface (corresponding to the other main surface 30s) of the support substrate 70 corresponding to the above opening by a spin coating method, and the lower reinforcing portion 73 g was applied by a photolithography method. After forming the resist pattern 110 (width: 50 μm) corresponding to the above, the support substrate 70 was etched to a depth of 150 μm (see FIG. 5 (B)).

Next, using a commercially available registry mover which is an organic solvent, the resin layer 100 and the resist pattern 110 are removed, and the support substrate 70 is further etched to the box layer 60 to form a support portion 72 g and a lower reinforcing portion 73 g. did. Next, the exposed box layer 60 and the hard mask patterns 80'a and 80'b formed on both sides of the SOI substrate 30 were simultaneously removed by etching to form a charged particle beam exposure mask 1.

In the charged particle beam exposure mask 1 thus produced, the height Z _{0 of the reinforcing portion 13 g, the angle θ 1} between the upper surface 13 gt of the reinforcing portion 13 g and the side wall surface 13 gs, and one end 13 gt A of the upper surface 13 gt of the reinforcing portion 13 g. (or 13GtB) and was measured and the width _{S 2} between the one end of the bottom 13gu 13guA (or 13guB). The measurement results are shown in Table 1 below.

[Example 2]
A hard mask pattern 80'b is formed on the lower surface of the support substrate 70 (corresponding to the other main surface 30s), and a corresponding pattern 81b having a width of 20 μm (corresponding to the second reinforcing portion 732 g) is formed, and the corresponding pattern 81b is formed. After applying the photoresist 110 (thickness: 20 μm) so as to cover the photoresist 110, the support substrate 70 was etched to a depth of 150 μm, and then the photoresist 110 covering the corresponding pattern 81b corresponding to the second reinforcing portion 732 g. And the support substrate 70 was further etched to the box layer 60 to form a first reinforcing portion 731 g and a second reinforcing portion 732 g continuous with the first reinforcing portion 731 g. In the same manner as above, a mask 1 for exposure to charged particle beams was produced.

In the charged particle beam exposure mask 1 thus produced, the height Z _{0 of the first reinforcing portion 131 g, the angle θ 1} between the upper surface 131 gt of the first reinforcing portion 131 g and the side wall surface 131 gs, and the first reinforcing portion 131 g. and the upper surface 131gt end 131GtA (or 131gtB), the width _{S 2,} the height of the second reinforcing portion 132g _{Z 1,} first end portion of the second reinforcing portion 132g between the one end of the bottom 131gu 131guA (or 131GuB) _{The angle θ 2} between the 132 gt and the side wall surface 132 gs, and the width between one end 132 gtA (or 132 gtB) of the first end 132 gt of the second reinforcing portion 132 g and one end 132 guA (or 132 gu B) of the second end 132 gu. It was measured S _6. The measurement results are shown in Table 1 below.

[Comparative Example 1]
A hard mask pattern 80'b is formed on the lower surface of the support substrate 70 (corresponding to the other main surface 30s), and a hard mask pattern (width: 50 μm) corresponding to the reinforcing portion having the same width as the lower reinforcing portion 73 g is formed. A mask for exposure to charged particle beams was produced in the same manner as in Example 1 above, except that the support substrate 70 was formed and the support substrate 70 was etched to the box layer 60 to form a reinforcing portion having the same height as the support portion 72 g. did.

_{The height Z 0 of the} reinforcing portion in the charged particle beam exposure mask thus produced _{, the angle θ 1} between the upper surface of the reinforcing portion and the side wall surface, and one end of the upper surface of the reinforcing portion are the same as one end of the upper surface. the width S ₂ between the one end of the bottom surface located on the side were measured. The measurement results are shown in Table 1 below.

Further, from the measurement results in Table 1, the reinforcing portion of the charged particle beam exposure mask 1 in Example 1 satisfies the above formula (1), and the second reinforcing portion of the charged particle beam exposure mask 1 in Example 2 is described above. It was confirmed that the equation (2) was satisfied. On the other hand, it was confirmed that the reinforcing portion of the charged particle beam exposure mask in Comparative Example 1 did not satisfy the above formula (1). From the above, the charged particle beam exposure mask on which the reinforcing portion satisfying the above formula (1) and the second reinforcing portion satisfying the above formula (2) are formed has sufficient strength, and according to the mask, the opening thereof. It is considered that the light transmitted through the portion 11 can be applied to the exposed object without being shielded by the deformed reinforcing portion.

It can be used in various manufacturing processes including steps using irradiation and exposure of charged particle beams.

1 ... Mask for charged particle beam exposure 10 ... Thin plate part 10a ... Non-transmissive part 11, 51 ... Opening B ... First surface F ... Second surface P ... Pattern area 12 ... Support part 12t ... First end part 12u ... First 2 end 13 ... Reinforcing part 131g ... 1st reinforcing part 132g ... 2nd reinforcing part 132gt ... 1st end part 132gu ... 2nd end part

Claims (6)

A thin plate portion having a first surface and a second surface facing the first surface,
A frame-shaped support portion that directs the thin plate portion from the first surface side, and
A charged particle beam exposure mask provided with a reinforcing portion that is continuous with the first surface of the thin plate portion and the inner side surface of the support portion and reinforces the thin plate portion.
In the plan view of the charged particle beam exposure mask, a plurality of openings through which the charged particle beam can pass are formed in the pattern region surrounded by the region supported by the support portion in the thin plate portion.
The reinforcing portion is continuous with the non-transmissive portion in the pattern region where the charged particle beam cannot pass, so as not to shield the charged particle beam passing through the opening, and is continuous with the non-transmissive portion. It has a first reinforcing portion to be formed and a second reinforcing portion continuous with the first reinforcing portion.
The first reinforcing portion includes a first minimum width portion continuous with the non-transparent portion and a first maximum width portion of the first reinforcing portion located farthest from the thin plate portion.
The second reinforcing portion includes a second minimum width portion continuous with the first maximum width portion and a second maximum width portion of the second reinforcing portion located farthest from the thin plate portion.
In the cross-sectional view of the charged particle beam exposure mask, the width of the first reinforcing portion is gradually increased from the first minimum width portion to the first maximum width portion, and the width of the second reinforcing portion is , The number gradually increases from the second minimum width portion toward the second maximum width portion.
In a cross-sectional view of the charged particle beam exposure mask, the width S ₄ of the first minimum width portion is the greater than the second width S ₇ of the minimum width portion, the width S ₁ of the first maximum width portion, said second charged particle beam exposure mask larger than the width S ₅ of the maximum width portion. In the cross-sectional view of the charged particle beam exposure mask placed on the horizontal plane, the angle formed by the side wall surface of the first reinforcing portion with respect to the horizontal plane is equal to or larger than the angle formed by the side wall surface of the second reinforcing portion with respect to the horizontal plane. The mask for charged particle beam exposure according to claim 1. The charged particle beam exposure mask according to claim 1 or 2, wherein the height of the first reinforcing portion is equal to or higher than the height of the second reinforcing portion. The support portion has a first end portion continuous with the first surface of the thin plate portion and a second end portion facing the first end portion.
The charged particle beam exposure mask according to any one of claims 1 to 3, wherein the second end portion of the support portion and the second maximum width portion are substantially located on the same surface. The method for manufacturing a charged particle beam exposure mask according to any one of claims 1 to 4.
A step of preparing a substrate having a first main surface and a second main surface facing the first main surface, and forming a first recess corresponding to the opening on the second main surface side of the substrate.
A step of forming a resin layer covering the second main surface on which the first recess is formed, and a step of forming the resin layer.
A step of forming a hard mask pattern including a first hard mask pattern corresponding to the support portion and a second hard mask pattern corresponding to the second reinforcing portion on the first main surface.
A step of forming a resist pattern corresponding to the first reinforcing portion on the first main surface, which covers the second hard mask pattern.
A step of etching the first main surface to a predetermined depth of the substrate using the resist pattern as an etching mask.
A step of etching the first main surface of the substrate to the predetermined depth and then removing the resist pattern.
A method for manufacturing a mask for charged particle beam exposure, comprising a step of etching the first main surface and penetrating the bottom surface of the first recess using the hard mask pattern as an etching mask after the resist pattern is removed. The method for manufacturing a mask for charged particle beam exposure according to claim 5, wherein the substrate is an SOI substrate in which a silicon layer is laminated via a silicon oxide layer.

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