JP7201044B2 - Charged particle beam exposure mask and manufacturing method thereof - Google Patents

Description

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

2. Description of the Related Art 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. Charged particle beam lithography includes a method in which a charged particle beam is directly drawn on the exposure target using a charged particle beam exposure system, and a stencil type charged particle beam exposure between the charged particle beam exposure system and the exposure target. There is a method in which a pattern is exposed through a mask for exposure.

As a stencil-type charged particle beam exposure mask, a mask having an opening (also referred to as 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 under the influence of stress or distortion of the substrate in the manufacturing process, or under the influence of water pressure during cleaning. In particular, in the case of a thin plate portion having a plurality of openings, the problem of deformation becomes significant. 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 of the thin plate portion is reinforced between a plurality of openings on the one surface that are continuous with the support portion. A charged particle beam exposure mask having a structure provided with a reinforcing portion for the charged particle beam exposure has been developed.

Japanese Patent No. 4570913

In the process of manufacturing a mask for charged particle beam exposure, for example, by using electron beam lithography or photolithography, a pattern for forming a reinforcing portion is formed on a substrate, and etching is performed using the pattern as a mask. When fabricating the reinforcing portion, for example, there is a possibility that phenomena such as misalignment of several μm, taper angle of the side wall due to etching, and tilt where the direction of etching is bent from the desired direction may occur. In particular, when the pitch of the openings (the distance between the centers of adjacent openings) is shortened, these phenomena can occur remarkably. Occurrence of these phenomena may cause deformation such as inclination or distortion in the reinforcing portion, making it impossible to precisely form the reinforcing portion according to the desired design. As a result, the charged particle beam that has passed through the opening is blocked by the reinforcing portion, making it impossible to accurately form an intended pattern.

The present disclosure has been made in view of the circumstances as described above, and an object thereof 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 supports the thin plate portion from the first surface side, and the thin plate portion and a reinforcing portion for reinforcing the thin plate portion, the thin plate in plan view of the charged particle beam exposure mask. A plurality of openings through which a charged particle beam can pass are formed in a pattern region surrounded by a region supported by the supporting portion of the portion, and the reinforcing portion is formed in the pattern region by the charged particle beam. a first reinforcing portion that is continuous with a non-transmissive portion through which rays cannot pass so as not to shield the charged particle beam that passes through the opening and that is continuous with the non-transmissive portion; a continuous second reinforcing portion, wherein the first reinforcing portion includes a first minimum width portion continuous to the non-permeable portion; a maximum width portion, wherein the second reinforcement portion includes a second minimum width portion continuous with the first maximum width portion, and a second maximum width portion of the second reinforcement portion located farthest from the thin plate portion. In a cross-sectional view of the mask for charged particle beam exposure, the width of the first reinforcing portion gradually increases from the first minimum width portion toward the first maximum width portion, and the second The width of the reinforcing portion gradually increases from the second minimum width portion toward the second maximum width portion, and in a cross-sectional view of the charged particle beam exposure mask, the width S4 of the _first minimum width portion is , the width _S7 of the second minimum width portion is larger than the width S1 of the first maximum width portion, and the width S1 of the _first maximum width portion is greater than the width _S5 of the second maximum width portion. .

In a cross-sectional view of the charged particle beam exposure mask placed on a horizontal plane, the angle formed by the side wall surfaces of the first reinforcing sections with respect to the horizontal plane is equal to or greater than the angle formed by the side wall surfaces of the second reinforcing sections with respect to the horizontal plane. The height of the second reinforcement portion may be equal to or higher than the height of the first reinforcement portion, and the support portion may include a first end portion continuous with the first surface of the thin plate portion and a The support portion may have a second end opposite to the first end, and the second end of the support portion and the second maximum width portion may be positioned substantially on the same plane. .

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

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 charged particle beam exposure mask according to the first embodiment of the present disclosure. FIG. 2A is a cross-sectional view of the charged particle beam exposure mask shown in FIG. 1 taken along line AA, and FIG. It is a figure, and is the schematic diagram which expanded the circumference|surroundings of the reinforcement part of the mask for charged particle beam exposure shown by FIG. 2(A), and drew the said reinforcement part exaggeratedly. FIG. 3A shares a plan view showing the charged particle beam exposure mask shown in FIG. 1, and the cross-sectional shape of the charged particle beam exposure mask shown in FIG. FIG. 3B is a cross-sectional view showing a different charged particle beam exposure mask according to the second embodiment of the present disclosure, and FIG. FIG. 3B is a diagram for enlarging the first reinforcing portion and the second reinforcing portion of the charged particle beam exposure mask shown in FIG. 3A and exaggerating the first reinforcing portion and the second reinforcing portion. It is a schematic diagram drawn by doing. FIG. 4 is a process chart for explaining the method of manufacturing the charged particle beam exposure mask according to the first embodiment of the present disclosure. FIG. 5 is a process drawing following FIG. 4 for explaining the method of manufacturing the charged particle beam exposure mask according to the first embodiment of the present disclosure. FIG. 6 is a process drawing following FIG. 5 for explaining the method of manufacturing the charged particle beam exposure mask according to the first embodiment of the present disclosure. FIG. 7 is a process diagram for explaining a method of manufacturing a charged particle beam exposure mask according to the second embodiment of the present disclosure. FIG. 8 is a process drawing following FIG. 7 for explaining the method of manufacturing the charged particle beam exposure mask according to the second embodiment of the present disclosure.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The drawings are schematic or conceptual, and the dimensions of each member, the ratio of sizes between members, etc., are not necessarily the same as the actual ones, and the same members, etc. are shown. However, the dimensions and ratios may be shown differently depending on the drawing. In addition, in the drawings attached to this specification, in order to facilitate understanding, there are cases where the shape, scale, length-to-width ratio, etc. of each part are changed from the actual product or exaggerated.

In this specification and the like, a numerical range represented using "to" means a range including the numerical values described before and after "to" as lower and upper limits, respectively. In this specification and the like, terms such as "film", "sheet", and "plate" are not distinguished from each other based on the difference in designation. For example, "plate" is a concept that includes members that can be generally called "sheets" and "films."

[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 of the charged particle beam exposure mask shown in FIG. FIG. 2B is a diagram for defining a formula for deriving the height of the reinforcing portion, and is an enlarged view around the reinforcing portion of the charged particle beam exposure mask shown in FIG. It is the schematic diagram which exaggerated and drew the said reinforcement part. As shown in FIGS. 1 and 2A, the charged particle beam exposure mask 1 has a substantially rectangular shape in plan view, and includes a thin plate portion 10, a supporting portion 12, and a reinforcing portion 13. As shown in FIG. Although the charged particle beam exposure mask 1 according to the first embodiment has a substantially rectangular shape in plan view, it is not limited to this. , a polygonal shape such as an octagon, or the like. 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 these.

The thin plate portion 10 has a first surface B and a second surface F facing the first surface B (FIG. 2(A)). A supporting portion 12 is provided on the first surface B side of the thin plate portion 10 , and the first surface B side of the thin plate portion 10 is supported by the supporting portion 12 . Further, on the side of the first surface B of the thin plate portion 10, a reinforcing portion 13 that is 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 plan view, and has a pattern region P surrounded by broken lines and a non-pattern region 10b surrounding the pattern region P. As shown in FIG. The pattern region P is composed of a plurality of openings 11 through which the charged particle beam can pass, and non-transmissive portions 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. As shown in FIG. The shape of the thin plate portion 10 can be appropriately set according to the planar view shape of the mask 1 for charged particle beam exposure.

The opening 11 is a through hole penetrating the thin plate portion 10 in the thickness direction, and the opening 11 shapes the charged particle beam emitted from the charged particle beam lithography device into a predetermined rectangle (square in the illustrated example). It can be used as a shaping aperture. The non-transmissive portion 10a has a lattice shape in a plan view, 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. As shown in FIG. Also, the non-transmissive portion 10a is continuous with the non-pattern region 10b. In FIG. 1, the 12 openings 11 are arranged in a grid pattern of 3 rows×4 columns in the pattern area P, but the shape of the openings 11 is not limited to this. , the number, arrangement, dimensions, etc., can be appropriately set according to the intended use of the mask 1 for charged particle beam exposure.

The thickness of the thin plate portion 10 is 0.2 μm to 30 μm, preferably 1 μm to 10 μm, more preferably 1 μm to 5 μm. Further, the material of the thin plate portion 10 is single crystal silicon (Si) when using an SOI (Silicon On Insulator) substrate as the substrate for manufacturing the charged particle beam exposure mask 1. can be set. For example, as the substrate for manufacturing the charged particle beam exposure mask 1, in addition to the SOI substrate, a silicon substrate; a silicon compound substrate such as silicon nitride, silicon carbide, or silicon oxide; A laminate or the like formed by laminating a plurality of layers made of selected materials can be used. Therefore, the material and thickness of the thin plate portion 10 can be appropriately set according to the substrate used as the substrate for manufacturing 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, the thickness 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 frame shape in plan view, is provided in the non-pattern region 10b on the first surface B side of the thin plate portion 10, and supports the thin plate portion 10 (non-pattern region 10b). Moreover, the support portion 12 has a laminated structure of an upper support portion 12h and a lower support portion 12g. When an SOI substrate is used as the substrate for manufacturing the charged particle beam exposure mask 1, the material of the upper supporting portion 12h is silicon oxide (SiO ₂ , a buried silicon oxide layer; also called a box layer), and the material of the lower supporting portion 12g. becomes single crystal silicon (Si). That is, in the supporting portion 12 , the upper supporting portion 12 h made of silicon oxide is fixed to the outer peripheral edge of the first surface B of the thin plate portion 10 . Thereby, the supporting portion 12 supports the thin plate portion 10 .

As described above, as the substrate for manufacturing the charged particle beam exposure mask 1, in addition to the SOI substrate, silicon substrates; silicon compound substrates such as silicon nitride, silicon carbide, and silicon oxide; A laminated substrate or the like obtained by laminating a plurality of layers made of a material selected from the above may be used. When the laminated substrate is used as the substrate for manufacturing the charged particle beam exposure mask 1, the laminated substrate has, for example, a layer for forming the thin plate portion 10 and a layer for forming the support portion 12, Any material may be used as long as it has etching selectivity between layers. 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. good too.

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 dimension of the frame shape in plan view, and the like. The height y of the support portion 12 can be appropriately set within a 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, so that the thin plate portion 10 (pattern region P) can be reinforced. In the first embodiment, the reinforcing portion 13 is arranged in a lattice shape (see FIG. 1) so as to be sandwiched between adjacent openings 11 in the pattern area P (or at a portion spaced apart from the periphery of each opening 11). 1 with a dotted line), but it is not limited to this mode. Depending on the number and layout of openings 11 formed in pattern region P, the form of reinforcing portion 13 can be appropriately set.

In the charged particle beam exposure mask 1 shown in FIGS. 1 and 2A, the reinforcing portion 13 is continuous with the supporting 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 of the charged particle beam exposure mask 1 is suppressed, and deformation of the thin plate portion 10 and breakage of the opening portion 11 are prevented. be able to. The reinforcing portion 13 also functions as a heat radiating member that releases heat generated by the charged particle beam colliding with the thin plate portion 10 to the outside.

Further, similarly to the supporting portion 12, the reinforcing portion 13 has a layered structure of an upper reinforcing portion 13h and a lower reinforcing portion 13g. When an SOI substrate is used as the substrate for manufacturing the mask 1 for charged particle beam exposure, similarly to the supporting portion 12, the material of the upper reinforcing portion 13h is silicon oxide (SiO ₂ ), and the material of the lower reinforcing portion 13g is simple. 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 material of the upper reinforcing portion 13h and the lower reinforcing portion 13g is the same as that of the supporting portion 12 described above. , and the configuration of the reinforcing portion 13 can also be configured 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 that passes through the opening 11, and the height _Z0 of the reinforcing portion 13g is , represented by the following formulas (1) to (5). Here, the reinforcing portion 13g of the charged particle beam exposure mask 1 shown in FIG. It is assumed that θ ₁ is greater than 90° of . The angle θ ₁ in the first embodiment is assumed to be about 91° to 95°, which is slightly larger than 90°. It is not limited to this. If the angle θ ₁ and the opposing angle θ ₁ ' are not the same angle, the width S ₂ can be derived based on the average angle θ _AVG between the angles θ ₁ and θ ₁ '. FIG. ₂ (B) exaggerates the reinforcing portion 13g so that the angled state can be easily recognized, and needless to say, the angle θ1 does not represent the actual angle. In FIG. 2B, the width of the non-transmitting portion 10a is _S0 , the width of the reinforcing portion 13g positioned between the opening 11A and the opening 11B adjacent to the reinforcing portion 13g is S1, and the thin plate portion ₁₀ On the closest side, an end 13gtA (or an end 13gtB positioned on the opening 11B side) of the upper surface 13gt of the reinforcing portion 13g located on the opening 11A side, and a bottom 13gu of the reinforcing portion 13g located on the opening 11A side. The width between the end 13guA (or the end 13guB located on the side of the opening 11B) and the end _10aA on the side of the opening 11A of the non-transmissive portion 10a (or the end 10aB on the side of the opening 11B) is defined as S2. , and the end portion 13guA (or end portion _13guB ) is S3. _The width S2 occurs when the reinforcing portion 13g has the taper angle θ1, 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. Also, the maximum width of the reinforcing portion 13g is assumed to be smaller than the width of the non-transmitting portion 10. FIG. Also, S4 represents the width of the upper surface _13gt of the reinforcing portion 13g, and this width S4 is obtained by subtracting _twice the width S2 from the width S1 of the _bottom surface _13gu of the reinforcing portion 13g. In one embodiment, any value greater than zero is acceptable.
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°<θ1< ₁₈₀ ° (5)

By setting the height _Z0 of the reinforcing portion 13 to the height represented by the formulas (1) to (5), the charged particle beam passing through the opening 11 is shielded by the deformed reinforcing portion 13, for example. Since the object to be exposed is irradiated with the light beams without being exposed, 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 exhibit sufficient strength to reinforce the thin plate portion 10. 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 addition, 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. not a thing The charged particle beam exposure mask 1 is formed by the corners forming part of the outer edge of the thin plate portion 12 and the support portion 13 , which are formed by the outer surface of the thin plate portion 12 entering more inward than the outer surface of the support portion 13 . It may have a stepped structure with corners forming 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 transported, etc., which facilitates handling and divides the multi-faceted chip. It is possible to suppress unnecessary force from being applied to the thin plate portion 12 when doing so.

[Second embodiment]
FIG. 3A shares a plan view showing the charged particle beam exposure mask shown in FIG. 1, and the cross-sectional shape of the charged particle beam exposure mask shown in 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, in which the surroundings of the first reinforcing portion and the second reinforcing portion of the charged particle beam exposure mask shown in FIG. 3A are enlarged and the first reinforcing portion and the second reinforcing portion are exaggerated; It is a schematic diagram drawn. In the charged particle beam exposure mask 1 according to the second embodiment, the lower reinforcing portion 13g of the reinforcing portion 13 includes the first reinforcing portion 131g and the second reinforcing portion 132g. It differs from the mask 1 for line exposure. Accordingly, in the second embodiment, substantially the same components as those in the first embodiment are denoted by the same reference numerals, detailed description thereof will be omitted, and the second reinforcing portion 132g will be mainly described.

As shown in FIG. 3, the second reinforcing portion 132g has a substantially rectangular cross-sectional shape, and a first end portion 132gt of the second reinforcing portion 132g extends to a bottom end portion 131gu (lower end portion in the drawing) of the first reinforcing portion 131g. consecutive. 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. Also, the second end 132gu facing the first end 132gt of the second reinforcing portion 132g and the second end 12u of the support portion 12 are positioned substantially on the same plane. A 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. As shown in FIG. Positioning the second end 132gu of the second reinforcing portion 132g and the second end 12u of the supporting portion 12 on the same plane reduces the height of the first reinforcing portion 131g in the second embodiment. However, the thin plate portion 10 can be sufficiently reinforced by the reinforcing portion 13 .

In the present embodiment, the width S ₅ of the second reinforcing portion 132g is preferably smaller than the width S ₁ of the first reinforcing portion 131g. 13). Here, the first reinforcing portion 131g of the charged particle beam exposure mask 1 shown in FIG. Assume that θ ₁ is greater than the desired 90°. The angle θ ₁ in the second embodiment is assumed to be about 91° to 95°, which is slightly larger than 90°. It is not limited to this. Further, the second reinforcing portion 132g of the charged particle beam exposure mask 1 shown in FIG. It is assumed that θ ₂ is greater than θ 2 . The angle θ2 in the _second embodiment is assumed to be about 91° to 95°, which is slightly larger than 90°. It is not limited to this. In FIG. 3B, the first reinforcing portion 131g and the second reinforcing portion 132g are exaggerated to make it easier to recognize the angled state, and the angles θ ₁ and θ ₂ are actual angles. Needless to say, it is not a representation. In FIG. 3B, the width of the non-transmitting portion 10a is S0, the width of the second reinforcing portion _132g located between the opening 11A and the opening 11B adjacent to the second reinforcing portion _132g is S5, S6 is the width between one end 132guA of the second end portion 132gu located on the opening 11A side and one end 132gtA of the first end portion 132gt located on the opening 11A side, and the upper surface _131gt of the first reinforcing portion 131g The width of the second reinforcing portion 132g is S4, and the width of the second end portion _132gu of the second reinforcing portion _132g is S7. The width S6 occurs when the _second reinforcing portion _132g has the taper angle θ2, and at this time, the width of the second end portion 132gu is larger than the width of the first end portion 132gt of the second reinforcing portion 132g. become a thing. Also, the width of the second end portion 132gu of the second reinforcing portion 132g is assumed to be smaller than the width of the bottom surface of the first reinforcing portion 131g. In the second embodiment, as long as the charged particle beam transmitted through the opening 11 is not shielded by the first reinforcing portion 131g and the second reinforcing portion 132g, the angles θ ₁ and θ ₂ are defined by the following formula (12 ), and the heights _Z0 and Z1 of the _first reinforcing portion 131g preferably satisfy the conditions 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)
_S7 >0 (10)
90°<θ ₂ <180° (11)
θ ₁ ≧θ ₂ (12)
Z ₁ ≧Z ₀ (13)

By setting the width S5 of the second reinforcing portion _132g to be smaller than the width S1 of the _first reinforcing portion 131g, preferably to the width represented by the formula (6), the charged particles transmitted through the opening 11 Since the line is irradiated onto the exposure target without being blocked by the second reinforcing portion 132g, the desired pattern can be formed with high accuracy. In order not to shield the charged particle beam that has passed 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 reduce the height of the lower reinforcing portion 13g as much as possible, but if the height of the lower reinforcing portion 13g is made too low, there is a possibility that the performance of reinforcing the thin plate portion 10 by the reinforcing portion 13 will deteriorate. Therefore, in the charged particle beam exposure mask 1 according to the second embodiment, it is particularly significant that the reinforcement section 13 has the second reinforcement section 132g. 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 to reinforce the thin plate portion 10 can be secured. Instead, it can be set as appropriate within the range of, for example, 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 131g is set higher than the height of the lower reinforcing portion 13g (see FIG. 2) in the first embodiment. Even if it is made low, the thin plate portion 10 can be sufficiently reinforced. The height of the first reinforcing portion 131g can be appropriately set within a range of 5 μm to 150 μm, for example.

[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 the method of manufacturing the charged particle beam exposure mask according to the first embodiment. A method for manufacturing the line exposure mask 1 will be described as an example.

As a substrate 30 for forming a mask for charged particle beam exposure, an SOI substrate is used in which a supporting substrate 70 mainly made of silicon single crystal, a box layer 60, and a single crystal silicon layer 50 are laminated in this order. prepare. The box layer 60 contains silicon oxide, and the thickness of the monocrystalline silicon layer 50 is 1 μm to 10 μm. A main surface 30m of the substrate 30 (here, the upper surface of the single-crystal silicon layer 50 and corresponding to the second surface F of the thin plate portion 10 shown in FIG. 2) and a main surface 30s opposite thereto (here, A hard mask material layer is formed on the lower surface of the support substrate 70 in the example. That is, a hard mask material layer 80a is formed on the single-crystal silicon layer 50 constituting the substrate 30, and a hard mask material layer 80b is formed on the supporting 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. Considering the workability of the substrate, the thickness of the substrate 30 is preferably 300 μm to 725 μm. .

Materials constituting the hard mask material layers 80a and 80b include, for example, silicon oxide; metal materials such as chromium and aluminum; is preferred. 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). This resist pattern 90 has a plurality of openings 91 in a region P' corresponding to the pattern region P shown in FIG. The resist pattern 90 can be formed by electron beam lithography using an electron beam sensitive resist, or by photolithography using a photosensitive resist. Furthermore, the resist pattern 90 may be formed by combining the electron beam lithography method and the photolithography method.

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

Etching of hard mask material layer 80a may be performed by wet etching or dry etching. When wet-etching the hard mask material layer 80a made of silicon oxide, an etchant such as hydrofluoric acid or a chemical containing hydrofluoric acid can be used as an etchant. On the other hand, when dry etching the hard mask material layer 80a made of silicon oxide, trifluoromethane (CHF ₃ ) gas, hexafluoroethane (C ₂ F ₆ ) gas, or the like can be used as an etching gas. The anisotropic dry etching can form the hard mask pattern 80'a having a size substantially as designed.

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

Next, a resin layer 100 is formed to cover the upper surface of the single crystal silicon layer 50 (corresponding to the second surface F of the thin plate portion 10) in which the concave portions 51 are formed. 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. Using this resist pattern as a mask, the hard mask material layer 80b is etched to form a hard mask. A pattern 80'b is formed (FIG. 5(A)). Note that 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 concave portion 51 and for the purpose of suppressing distortion when the support substrate 70 is etched in a post-process. Therefore, the thickness of the resin layer 100 can be appropriately set within the range of 5 μm to 30 μm. Although such a resin layer 100 is formed over the entire substrate in the illustrated example, it may be formed within a range covering at least the recess 51 . As a material for forming the resin layer 100, a known resin material used as a resist or the like can be used. can be The thickness of the resin layer 100 can be controlled by adjusting the viscosity of the solution by adjusting the concentrations of the resin material and additives, and by adjusting the rotational speed of the substrate during application of the solution. If the desired thickness cannot be obtained by applying the solution once, the application and curing of the solution may be repeated multiple times until the desired thickness of the resin layer is obtained.

The hard mask pattern 80'b has a rectangular opening 85 in a plan view corresponding to the pattern area P shown in FIGS. 1 and 2 (indicated by broken lines in FIG. 1). The opening 85 has an opening size and an opening shape suitable for forming a support portion 72g, which will be described later, in consideration of the etching method, the 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). , to form a plurality of openings 75 facing the recesses 51 (FIG. 5B). The “predetermined depth” for etching the support substrate 70 can be appropriately set to the extent that the reinforcing portion 13 having a height _Z0 represented by the above formulas (1) to (5) can be formed.
The resist pattern 110 can be formed by electron beam lithography using an electron beam sensitive resist, or by photolithography using a photosensitive resist. Furthermore, the resist pattern 110 may be formed by combining electron beam lithography and photolithography.

After the support substrate 70 is etched to the above-described "predetermined depth", the resin layer 100 and the resist pattern 110 are removed, and the support substrate 70 is moved upward in the direction of arrow E using the hard mask pattern 80'b as an etching mask. Further, dry etching is performed (FIG. 5(C)). Also 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 (lower surface of the box layer 60) corresponding to the non-pattern region 50b of the single crystal silicon layer 50, and a position (lower surface of the box layer 60) corresponding to the region 50a. A lower reinforcing portion 73g is formed in the . The box layer 60 exposed between the supporting portion 72g and the lower reinforcing portion 73g formed by etching the supporting substrate 70 and between the lower reinforcing portions 73g is removed in a post-process by etching the main surface 30s of the substrate 30. By etching from the side, the opening 11 is formed through the bottom surface of the recess 51 . It should be noted that 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 using an organic solvent, or may be removed by ashing such as oxygen plasma treatment. As an organic solvent, for example, a registry remover can be used. After removing the resin layer 100 and the resist pattern 110 using a resist remover, organic matter remaining on the exposed hard mask patterns 80'a and 80'b and the surface of the box layer 60 exposed by forming the recesses 51 is removed. SPM cleaning may be performed for removal. SPM cleaning is also called sulfuric acid-hydrogen peroxide water cleaning, and for example, a chemical solution mixed with 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 matter by utilizing a strong oxidizing action. After SPM cleaning, the substrate may be dried by IPA drying. The removal of the resin layer 100 and the resist pattern 110 may be performed in the same step or in separate steps.

Next, the box layer 60 is etched from the main surface 30s side of the substrate 30 to form the opening 11 through which the bottom surface of the recess 51 penetrates, and then the hard mask patterns 80'a and 80'b are removed. Thus, a charged particle beam exposure mask 1 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. . Note that 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. In addition, the hard mask pattern 80'a and the hard mask pattern 80'b may be removed at the same time when the box layer 60 is etched. Alternatively, after etching the box layer 60 exposed between the supporting portion 72g and the lower reinforcing portion 73g and between the lower reinforcing portions 73g to form the openings 11, the resin layer 100 may be removed. good.

After etching the box layer 60 and removing the hard mask patterns 80'a and 80'b, the substrate 30 is subjected to SPM cleaning, APM cleaning, and hydrofluoric acid (HF) cleaning. After cleaning the substrate 30, the mask for charged particle beam exposure may be dried by IPA drying. Here, _APM cleaning is also called _{ammonia -} hydrogen _peroxide water cleaning. An example of heating and using can be given. APM cleaning is a cleaning method that is effective in removing organic substances and insoluble particles.

In the first embodiment, misalignment of the resist pattern 110 may occur, and taper may occur on the sidewall of the opening 75 formed by dry etching the support substrate 70 using the resist pattern 110 as an etching mask. , a lower reinforcing portion 73g having an inclination, distortion, or the like can be formed. However, by dry-etching the supporting substrate 70 using the hard mask pattern 80'b as an etching mask after removing the resist pattern 110, the lower reinforcing portion 73g is formed with a height lower than that of the supporting portion 72g. As a result, even if misalignment or taper occurs, in the manufactured charged particle beam exposure mask 1, the charged particle beam passing through the opening 11 can be prevented from being shielded by the lower reinforcing portion 73g. can.

Therefore, according to the method of manufacturing the charged particle beam exposure mask in the first embodiment, the charged particle beam that has passed through the opening 11 is not blocked by the lower reinforcing portion 73g, and does not reach the exposure target. A high-quality charged particle beam exposure mask 1 that can be irradiated can be manufactured.

In the first embodiment, an SOI substrate is used as the substrate 30. However, the substrate 30 is not limited to this. A laminated substrate or the like in which a plurality of layers made of a material selected from among desired materials are laminated can be used. When the laminated substrate is used as the substrate 30, for example, the charged particle beam exposure mask 1 shown in FIG. You may use the laminated substrate which has as the board|substrate 30. FIG. In this case, the laminated substrate may be one that allows selective etching between the layer that will be the thin plate portion 10 and the layer that will be the support portion 12, and the layer that will be the thin plate portion 10 is the thin plate portion Any material may be used as long as it forms a self-supporting thin film (membrane) to the extent that 10 can be maintained in a state having openings 11 . Moreover, in order to provide etching selectivity between the layer forming the thin plate portion 10 and the layer forming the support portion 12, the layered substrate may have a layered structure of three or more layers. When using such a laminated substrate, by setting 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 in the case of using the SOI substrate described above. can be manufactured. In the present disclosure, the term "etching selectivity between different layers and materials" means that etching rates may differ when etching is performed under the same conditions.

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

In FIG. 4C, after the recesses 51 are formed in the single crystal silicon layer 50, the upper surface of the single crystal silicon layer 50 (corresponding to the second surface F of the thin plate portion 10) in which the recesses 51 are formed is covered. A resin layer 100 is formed on the surface. In addition, a resist pattern (not shown) having a plurality of openings is formed in the hard mask material layer 80b, and the hard mask material layer 80b is etched using this resist pattern as an etching mask. 'b (first hard mask pattern) and a corresponding pattern 81b (second hard mask pattern) corresponding to the second reinforcing portion 132g are formed (FIG. 7A). In the second embodiment, the width of the resist pattern is set so that the _first reinforcing portion 131g having a width S1 represented by the above formulas (1) to (5) and the above formula (7) is formed. The width of the corresponding pattern 81b is set so as to form the second reinforcing portion 132g having a width S ₅ represented by equations (1) to (13).
Note that the hard mask material layer 80b can be etched by wet etching or dry etching. In this embodiment, in addition to the hard mask pattern 80'b shown in FIG. 7A, a corresponding pattern 81b is formed. different (see FIG. 5(A)).

The resin layer 100 is formed for the purpose of protecting the concave portion 51 and for the purpose of suppressing distortion when the support substrate 70 is etched in a post-process. Therefore, the thickness of the resin layer 100 can be appropriately set within the range of 5 μm to 30 μm. Although such a resin layer 100 is formed over the entire substrate in the illustrated example, it may be formed within a range covering at least the recess 51 . As a material for forming the resin layer 100, a known resin material used as a resist or the like can be used. can be The thickness of the resin layer 100 can be controlled by adjusting the viscosity of the solution by adjusting the concentrations of the resin material and additives, and by adjusting the rotational speed of the substrate during application of the solution. If the desired thickness cannot be obtained by applying the solution once, the application and curing of the solution may be repeated multiple times until the desired thickness of the resin layer is obtained.

In this embodiment, the hard mask pattern 80'b has a substantially rectangular opening 85 corresponding to the pattern area P (indicated by the broken line in FIG. 1) shown in FIGS. Located within 85 are a plurality of corresponding patterns 81b. 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, 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 side surfaces of the corresponding pattern 81b is formed on the lower surface 30s of the support substrate 70, and the resist pattern 110 is used as an etching mask. A plurality of openings 75 are formed by etching the support substrate 70 upward in the direction of arrow E to a predetermined depth (FIG. 7(B)). The resist pattern 110 can be formed by electron beam lithography using an electron beam sensitive resist, or by photolithography using a photosensitive resist. Also, the resist pattern 110 can be formed by combining electron beam lithography and photolithography. The "predetermined depth" is a depth appropriately set according to the height of the first reinforcing portion 731g. 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 includes the first reinforcing portion _731g having a height Z0 represented by the above formulas (1) to (5) and the height Z0 derived from the above formula (6). It can be appropriately set to the extent that _one second reinforcing portion 732g can be formed.

After etching the support substrate 70 to the above-mentioned "predetermined depth", the resin layer 100 and the resist pattern 110 are removed, and the support substrate 70 (the pattern 81b is used as an etching mask) is etched using the hard mask pattern 80'b and the corresponding pattern 81b as an etching mask. 732g) is further etched upward in the direction of arrow E (in the direction of arrow e on both side surfaces of the second reinforcing portion 732g) (FIG. 7(C)). Also 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-pattern region 50b of the single crystal silicon layer 50, and a first reinforcing portion 731g is formed at a position corresponding to the region 50a. Furthermore, in the second embodiment, a second reinforcing portion 732g is formed that is continuous with the bottom side of the first reinforcing portion 731g. The box layer 60 exposed between the supporting portion 72g and the first reinforcing portion 731g formed by etching the supporting substrate 70 and between the first reinforcing portions 731g is removed as the main portion of the substrate 30 in a post-process. By etching from the surface 30s side, the opening 11 is formed through the bottom surface of the recess 51 . It should be noted that 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 using an organic solvent, or may be removed by ashing such as oxygen plasma treatment. As an organic solvent, for example, a registry remover can be used. After removing the resin layer 100 and the resist pattern 110 using a resist remover, the organic matter remaining on the exposed hard mask patterns 80'a and 80'b and the surface of the box layer 60 exposed by forming the recesses 51 is removed. SPM cleaning may be performed for removal. SPM cleaning is also called sulfuric acid and hydrogen peroxide water cleaning, and an example of using a chemical solution mixed with H ₂ O ₂ :H ₂ SO ₄ =3:1 by heating to 70° C. to 80° C. can be mentioned. SPM cleaning is a cleaning method that is effective in removing organic matter by utilizing a strong oxidizing action. After SPM cleaning, the substrate may be dried by IPA drying. The removal of the resin layer 100 and the resist pattern 110 may be performed in the same step or in separate steps.

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, the charged particle beam exposure mask 1 is formed (FIG. 8). In the present embodiment, the depth of the openings 11 in the charged particle beam exposure mask 1 thus formed corresponds to the thickness of the single crystal silicon layer 50, and is within the range of 1 μm to 10 μm. is the depth of Note that 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. Simultaneously with the etching of the box layer 60, the hard mask pattern 80'a and the hard mask pattern 80'b may be removed. Alternatively, after etching the box layer 60 exposed between the supporting portion 72g and the first reinforcing portion 731g and between the first reinforcing portions 731g to form the openings 11, the resin layer 100 may be removed. good.

SPM cleaning, APM cleaning, and hydrofluoric acid (HF) cleaning are performed on the substrate 30 after etching the box layer 60 and removing the hard mask patterns 80'a and 80'b and the corresponding pattern 81b. done. After cleaning the substrate 30, the mask may be dried by IPA drying. Here, _APM cleaning is also called _{ammonia -} hydrogen _peroxide water cleaning. An example of heating and using can be given. APM cleaning is a cleaning method effective in removing organic substances and insoluble particles.

In the second embodiment, misalignment of the resist pattern 110 may occur, and taper may occur on the sidewall of the opening 75 formed by dry etching the support substrate 70 using the resist pattern 110 as an etching mask. , a first reinforcing portion 731g and a second reinforcing portion 732g having inclinations, distortions, or the like may 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, whereby the first reinforcing portion 731g is formed at a height lower than that of the support portion 72g. The second reinforcing portion 732g is formed with a width smaller than that of the first reinforcing portion 731g. As a result, even if misalignment or taper occurs, in the charged particle beam exposure mask 1 to be manufactured, the charged particle beam passing through the opening 11 is shielded by the first reinforcing portion 731g and the second reinforcing portion 732g. can prevent

As described above, the charged particle beam transmitted through the opening 11 is shielded by the deformed first reinforcing portion 731g and the second reinforcing portion 732g by the charged particle beam exposure mask manufacturing method according to the second embodiment. It is possible to manufacture a high-quality charged particle beam exposure mask 1 that can be irradiated onto an exposure object without any need.

EXAMPLES 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 substrate>
As the substrate 30, a support substrate 70 (thickness: 400 μm) mainly made of 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) are arranged in this order. A laminated SOI substrate 30 having a diameter of 200 mm was prepared.

<Preparation of Mask for Charged Particle Beam Exposure>
Next, using the above SOI substrate 30, the hard mask material layer 80a, which is a silicon oxide film with a thickness of 1 μm, is thermally oxidized on the single crystal silicon layer 50 located on the one main surface 30m side of the SOI substrate 30. Simultaneously with the formation of the hard mask material layer 80a, a hard mask material layer which is a silicon oxide film with a thickness of 1 μm is formed on the supporting substrate 70 located on the other main surface 30s side of the SOI substrate 30. 80b was formed by thermal oxidation (see FIG. 4A).

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

Next, the resist layer 90 on one main surface 30m side of the SOI substrate 30 is developed to form a plurality of rectangular concave portions 91 (10 μm×30 μm) arranged in a grid pattern of 4 columns×3 rows. A resist pattern containing 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 using a fluorine-based gas (O ₂ : 5 sccm, CHF ₃ : 45 sccm) to obtain single crystal silicon. A plurality of recesses 51 were formed in a region of the layer 50 corresponding to the pattern region P'.
Next, a solution of a resin material was applied onto the single-crystal silicon layer 50 by spin coating so as to cover the plurality of recesses 51 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 etched by reactive ion etching using a fluorine-based gas in the same manner as the etching of the hard mask material layer 80a on the one main surface 30m side of the SOI substrate 30 described above. The hard mask material layer 80b on the surface 30s side is etched to form a hard mask pattern 80'b.

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

Next, using a commercially available resist remover which is an organic solvent, the resin layer 100 and the resist pattern 110 are removed, the support substrate 70 is further etched down to the box layer 60, and the support portion 72g and the lower reinforcement portion 73g are formed. bottom. 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 the mask 1 for charged particle beam exposure.

Height Z ₀ of reinforcing portion 13g, angle θ ₁ between upper surface 13gt of reinforcing portion 13g and side wall surface 13gs, and one end 13gtA of upper surface 13gt of reinforcing portion 13g in mask 1 for charged particle beam exposure manufactured in this way (or 13gtB) and the width S2 between one end 13guA (or 13guB) of the bottom surface _13gu . The measurement results are shown in Table 1 below.

[Example 2]
A hard mask pattern 80'b is formed on the lower surface (corresponding to the other main surface 30s) of the support substrate 70, and a corresponding pattern 81b (corresponding to the second reinforcing portion 732g) having a width of 20 μm is formed. , the support substrate 70 is etched to a depth of 150 μm, and then the photoresist 110 covering the corresponding pattern 81b corresponding to the second reinforcing portion 732g. is removed, and the supporting substrate 70 is further etched up to the box layer 60, thereby forming the first reinforcing portion 731g and the second reinforcing portion 732g continuous with the first reinforcing portion 731g. A charged particle beam exposure mask 1 was produced in the same manner as in the above.

The height Z ₀ of the first reinforcing portion 131g, the angle θ ₁ between the upper surface 131gt of the first reinforcing portion 131g and the side wall surface 131gs, and the first reinforcing portion 131g in the charged particle beam exposure mask 1 thus manufactured Width S ₂ between one end 131gtA (or 131gtB) of the upper surface 131gt and one end 131guA (or 131guB) of the bottom surface 131gu, height Z ₁ of the second reinforcing portion 132g, the first end of the second reinforcing portion 132g The angle θ ₂ between 132gt and the side wall surface 132gs, and the width between one end 132gtA (or 132gtB) of the first end 132gt of the second reinforcing portion 132g and one end 132guA (or 132guB) of the second end 132gu _S6 was measured. The measurement results are shown in Table 1 below.

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

In the mask for charged particle beam exposure manufactured in this way, the height _{Z0 of the} reinforcing portion, the angle θ1 between the upper surface of the reinforcing portion and the side wall surface, and _one end of the upper surface of the reinforcing portion and one end of this upper surface are the same. The width S2 between one end of the bottom surface located on the _side was 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 satisfies the above It was confirmed that the formula (2) was satisfied. On the other hand, it was confirmed that the reinforcing portion of the mask for charged particle beam exposure in Comparative Example 1 did not satisfy the above formula (1). As described above, the charged particle beam exposure mask in which the reinforcing portion satisfying the above formula (1) and the second reinforcing portion satisfying the above formula (2) are formed has sufficient strength. It is considered that the light transmitted through the portion 11 can be irradiated onto the object to be exposed without being blocked by the reinforcing portion after deformation.

It can be used for various manufacturing processes including processes using charged particle beam irradiation and exposure.

DESCRIPTION OF SYMBOLS 1... Charged particle beam exposure mask 10... Thin plate part 10a... Non-transmissive part 11, 51... Opening part B... 1st surface F... 2nd surface P... Pattern area 12... Support part 12t... 1st end part 12u... 3rd 2 Ends 13 Reinforcing Part 131g First Reinforcing Part 132g Second Reinforcing Part 132gt First End 132gu Second End

Claims (6)

a thin plate portion having a first surface and a second surface facing the first surface;
a frame-shaped support portion that supports the thin plate portion from the first surface side;
A charged particle beam exposure mask comprising a reinforcing portion that is continuous with the first surface of the thin plate portion and the inner surface of the support portion and that reinforces the thin plate portion,
In a plan view of the charged particle beam exposure mask, a plurality of openings through which a charged particle beam can pass are formed in a pattern region surrounded by a region of the thin plate portion supported by the supporting portion,
The reinforcing portion is continuous with a non-transmissive portion through which the charged particle beam cannot pass in the pattern area so as not to block the charged particle beam passing through the opening, and is continuous with the non-transmissive portion. and a second reinforcing portion continuous with the first reinforcing portion,
The first reinforcing portion includes a first minimum width portion continuous to the non-transmissive portion, and a first maximum width portion located farthest from the thin plate portion among the first reinforcing portions,
The second reinforcing portion includes a second minimum width portion continuous with the first maximum width portion, and a second maximum width portion located farthest from the thin plate portion among the second reinforcing portions,
In a cross-sectional view of the charged particle beam exposure mask, the width of the first reinforcing portion gradually increases from the first minimum width portion toward the first maximum width portion, and the width of the second reinforcing portion is , gradually increasing 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 S4 of the first minimum width portion is larger than the width _S7 of the _second minimum width portion, and the width S1 of the _first maximum width portion is A charged particle beam exposure mask larger than the width _S5 of the second maximum width portion. In a cross-sectional view of the charged particle beam exposure mask placed on a horizontal plane, the angle formed by the side wall surfaces of the first reinforcing section with respect to the horizontal plane is greater than or equal to the angle formed by the side wall surfaces of the second reinforcing sections with respect to the horizontal plane. A mask for charged particle beam exposure according to claim 1 . 3. The mask for charged particle beam exposure according to claim 1, wherein the height of the second reinforcing portion is equal to or higher than the height of the first reinforcing portion. The support portion has a first end continuous with the first surface of the thin plate portion and a second end facing the first end,
4. The mask for charged particle beam exposure according to claim 1, wherein the second end portion of the supporting portion and the second maximum width portion are positioned substantially on the same plane. A method for manufacturing the charged particle beam exposure mask according to any one of claims 1 to 4,
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;
forming a resin layer covering the second main surface in which the first recess is formed;
forming on the first main surface 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;
forming, on the first main surface, a resist pattern corresponding to the first reinforcing portion and covering the second hard mask pattern;
using the resist pattern as an etching mask to etch the first main surface of the substrate to a predetermined depth;
removing the resist pattern after etching the first main surface of the substrate to the predetermined depth;
After removing the resist pattern, using the hard mask pattern as an etching mask, etching the first main surface to penetrate the bottom surface of the first concave portion. 6. The method of 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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