Pellicle and method for manufacturing the same

Abstract

To provide: a pellicle capable of suppressing cracking of a pellicle film; and a method for manufacturing the pellicle.SOLUTION: A pellicle 1 comprises: a silicon (Si) border 11 including a boron (B)-containing Si layer 113; and a pellicle film 12 formed on a surface 113a side of the Si layer 113. Preferably, the Si border 11 includes a through-hole 13, and the pellicle film 12 is exposed on the bottom surface of the through-hole 13.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a pellicle and a method for manufacturing a pellicle, and more particularly to a pellicle that can suppress cracking of a pellicle membrane and a method for manufacturing a pellicle. [Background technology]

[0002] In photolithography technology used in the manufacturing process of semiconductor devices, a resist pattern of the required shape is created on a semiconductor wafer by applying resist to the semiconductor wafer and irradiating the required areas of the applied resist with exposure light using a photomask. When irradiating the resist with exposure light, the photomask is covered with a dustproof cover called a pellicle to prevent foreign matter from adhering to the photomask. A material that is highly transparent to exposure light and highly resistant to exposure light (less deterioration or deformation at high temperatures) is suitable for the pellicle film of the pellicle, and Si (silicon) is used.

[0003] In the manufacturing process of semiconductor devices, the demand for miniaturization of photolithography technology is increasing along with the miniaturization of semiconductor devices. In recent years, it has become mainstream to use light (248 nm) from a KrF (krypton fluoride) excimer laser as a light source or light (193 nm) from an ArF (argon fluoride) excimer laser as a light source for exposure. In addition, the use of EUV (Extreme Ultra Violet) light (13.5 nm), which has a shorter wavelength than these lights, is also being considered.

[0004] When using KrF excimer lasers or ArF excimer lasers as light sources, organic thin films are used as pellicle films. However, when the wavelength of the exposure light becomes shorter, such as EUV light, the energy that the pellicle film receives from the exposure light increases. For this reason, in photolithography using EUV light, the use of inorganic thin films with high transmittance and high resistance to EUV light is being considered. This type of inorganic thin film includes Si, SiN (silicon nitride), C (carbon) (graphite, graphene, diamond-like carbon (DLC), amorphous carbon, etc.), and SiC (silicon carbide).

[0005] Techniques relating to a method for manufacturing a pellicle film made of SiC are disclosed, for example, in the following Patent Documents 1 and 2. The following Patent Document 1 discloses a method for manufacturing a compound semiconductor substrate, including a step of forming a SiC film on a front surface of a Si substrate, and a step of removing at least a part of the rear surface of the Si substrate by wet etching. In the step of removing at least a part of the rear surface of the Si substrate, the Si substrate and the SiC film are moved relative to a chemical solution used for wet etching.

[0006] The following Patent Document 2 discloses a pellicle including a pellicle membrane and a support material that supports the pellicle membrane. The pellicle membrane is made of DLC, amorphous carbon, graphite, silicon carbide, or the like. The pellicle frame is made of silicon, metal, or the like. This pellicle is manufactured by etching a substrate to form the support material, and forming the pellicle membrane on the substrate.

[0007] In addition, Non-Patent Document 1 describes a P + Type Si thin film crystal layer <110> The Young's modulus in the direction is <110> It is disclosed that the Young's modulus is 26% to 28% lower. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2017-218358 A [Patent Document 2] International Publication No. 2014 / 187710 [Non-patent literature]

[0009] [Non-Patent Document 1] XIAOYI DING, et al., "Residual Stress and Mechanical Properties of Boron-doped p +-Silicon Films", Sensors and Actuators, A21-A23 (1990) p.866. Summary of the Invention [Problem to be solved by the invention]

[0010] In order to improve the transmittance of the pellicle membrane, it is necessary to make the pellicle membrane thinner. However, when the pellicle membrane is made thinner, the mechanical strength of the pellicle membrane decreases, making the pellicle membrane more susceptible to cracking. Since SiC is a typical hard and brittle material, cracking is particularly likely to occur when the pellicle membrane is made of SiC.

[0011] The problem that the pellicle film becomes more likely to crack when the pellicle film is thinned is not limited to the case where the pellicle film is made of SiC, but occurs with any pellicle film. The problem that the pellicle film becomes more likely to crack when the pellicle film is thinned can be caused by stress from a border (support) having an arbitrary shape.

[0012] The present invention is intended to solve the above problems, and its object is to provide a pellicle and a method for manufacturing a pellicle that can prevent cracking of the pellicle membrane. [Means for solving the problem]

[0013] A pellicle according to one aspect of the present invention includes a border including a Si layer containing B, and a Si layer A pellicle membrane formed on one of the main surfaces. The Si layer has a P-type conductivity and contains Si crystals. .

[0014] In the above pellicle, the resistivity of the Si layer is preferably greater than 0 and equal to or less than 0.02 Ω·cm.

[0015] In the above pellicle, the pellicle membrane preferably has a thickness of 10 nm or more and 50 nm or less.

[0017] The above pellicle preferably further comprises an adhesive film for adhering the pellicle film and the Si layer.

[0018] In the above pellicle, the pellicle membrane is preferably made of SiC.

[0019] In the above pellicle, preferably, border includes a through hole, and the pellicle membrane is exposed at the bottom surface of the through hole.

[0020] A method for producing a pellicle according to another aspect of the present invention includes: A Si layer having a P-type conductivity and containing Si crystals and forming a pellicle film on one main surface side of the Si layer.

[0021] In the above-mentioned production method, preferably, The pellicle membrane is exposed on the bottom surface. Through hole In the Si layer The method further includes forming a border including a Si layer by forming a Si layer on the substrate. do.

[0028] In the above manufacturing method, the pellicle membrane is preferably made of SiC. Effect of the Invention

[0029] According to the present invention, it is possible to provide a pellicle that can prevent cracking of the pellicle membrane and a method for manufacturing a pellicle. [Brief description of the drawings]

[0030] [Figure 1] 1 is a cross-sectional view showing a configuration of a pellicle 1 in a first embodiment of the present invention. [Diagram 2] 2 is a cross-sectional view showing a configuration of a modified example of pellicle 1 in the first embodiment of the present invention. FIG. [Diagram 3] 1 is a plan view showing the configuration of a pellicle 1 when viewed from a direction perpendicular to a surface 12a of a pellicle film 12 in a first embodiment of the present invention. [Figure 4] 1 is a cross-sectional view showing a first step of a method for manufacturing pellicle 1 in accordance with a first embodiment of the present invention. [Diagram 5] 4 is a cross-sectional view showing a second step of the method for manufacturing pellicle 1 in the first embodiment of the present invention. FIG. [Figure 6] 6 is a cross-sectional view showing a first step of a modified example of the step shown in FIG. 5. FIG. [Figure 7] 6 is a cross-sectional view showing a second step of a modified example of the step shown in FIG. 5. FIG. [Figure 8] 4 is a cross-sectional view showing a third step of the method for manufacturing pellicle 1 in the first embodiment of the present invention. FIG. [Figure 9] 4 is a cross-sectional view showing a fourth step of the method for manufacturing pellicle 1 in the first embodiment of the present invention. FIG. [Figure 10] 5A to 5C are cross-sectional views showing a fifth step of the method for manufacturing pellicle 1 in the first embodiment of the present invention. [Figure 11] FIG. 2 is a diagram illustrating a first method of wet etching of Si in the first embodiment of the present invention. [Figure 12] FIG. 4 is a diagram illustrating a second method of wet etching of Si in the first embodiment of the present invention. [Figure 13] FIG. 11 is a diagram illustrating a third method of wet etching of Si in the first embodiment of the present invention. [Figure 14] 2 is an enlarged view of part A in the pellicle 1 shown in FIG. [Figure 15] FIG. 2 is a diagram illustrating an effect of the first embodiment of the present invention. [Figure 16] 10 is a cross-sectional view showing a configuration of a pellicle 1 in a second embodiment of the present invention. FIG. [Figure 17] 11 is a cross-sectional view showing a first step of a method for manufacturing a pellicle 1 in a second embodiment of the present invention. FIG. [Figure 18] 11 is a cross-sectional view showing a second step of the method for manufacturing pellicle 1 in the second embodiment of the present invention. FIG. [Figure 19] 13 is a cross-sectional view showing a third step of the method for manufacturing pellicle 1 in the second embodiment of the present invention. FIG. [Figure 20] 13 is a cross-sectional view showing a fourth step of the method for manufacturing pellicle 1 in the second embodiment of the present invention. FIG. [Figure 21] 13 is a cross-sectional view showing a fifth step of the method for manufacturing pellicle 1 in the second embodiment of the present invention. FIG. [Figure 22] FIG. 4 is a diagram showing the yield rate of each of samples A to D in an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0032] [First embodiment]

[0033] 1 is a cross-sectional view showing the configuration of a pellicle 1 according to a first embodiment of the present invention, taken along a plane perpendicular to a surface 12a of a pellicle membrane 12.

[0034] With reference to FIG. 1, a pellicle 1 (an example of a pellicle) in this embodiment includes a Si border (support) 11 (an example of a border) and a pellicle film 12 (an example of a pellicle film).

[0035] The Si border 11 has a ring-shaped planar shape surrounding the through hole 13 (an example of a through hole). The Si border 11 includes a front surface 11a, a back surface 11b, and a side surface 11c. The Si border 11 is a border including a Si layer 113. In FIG. 1, the Si border 11 is made of the Si layer 113. The (100) plane of Si is exposed on the front surface 11a of the Si border 11. The (111) plane of the Si layer 113 or the (110) plane of Si may also be exposed on the front surface 11a of the Si border 11.

[0036] The Si layer 113 contains B. It is preferable that the concentration of B in the Si layer 113 is as high as possible without precipitating B in the Si crystal. Due to the action of B in the Si layer 113, the Si layer 113 has a P-type conductivity. Furthermore, due to the action of B in the Si layer 113, the Si layer 113 has a resistivity greater than 0 and equal to or less than 0.02 Ω·cm, preferably equal to or less than 0.005 Ω·cm.

[0037] The pellicle film 12 is made of SiC and is formed on the surface 113a of the Si layer 113. The pellicle film 12 is supported by the Si border 11. The pellicle film 12 includes a surface 12a, a back surface 12b, and a side surface 12c. The center of the back surface 12b of the pellicle film 12 is exposed at the bottom of the through-hole 13. The pellicle film 12 is not formed on the back surface 11b of the Si border 11, and the back surface 11b of the Si border 11 is exposed.

[0038] The pellicle film 12 has a thickness w of 10 nm or more and 10 μm or less. The thickness w is preferably 1 μm or less, more preferably 500 nm or less, and most preferably 50 nm or less. As the thickness w of the pellicle film 12 becomes thinner, the transmittance of the pellicle film 12 improves, but the mechanical strength of the pellicle film 12 decreases.

[0039] The pellicle film 12 in this embodiment is epitaxially grown on the surface 113a (surface 11a of the border 11) side of the Si layer 113. In other words, the structure of the SiC crystals in the pellicle film 12 at least in the portion in contact with the surface 113a of the Si layer 113 is influenced by the Si crystals in the Si layer 113 and is changed from the structure of the bulk SiC crystals. The pellicle film 12 is in contact with the surface 113a of the Si layer 113.

[0040] The pellicle film 12 is made of single crystal 3C-SiC, polycrystalline 3C-SiC, amorphous SiC, etc. In particular, when the pellicle film 12 is epitaxially grown on the surface of the Si layer 113, the pellicle film 12 is generally made of 3C-SiC.

[0041] The border only needs to include a Si layer, and the SiO 2 The border may further include a film made of other material such as a silicon oxide film or a silicon nitride film. The border may also include a sapphire substrate and a Si layer formed on the sapphire substrate.

[0042] 2 is a cross-sectional view showing the configuration of a modified example of pellicle 1 in the first embodiment of the present invention. Note that Fig. 2 is a cross-sectional view taken along a plane perpendicular to surface 12a of pellicle membrane 12.

[0043] 2, in this modification, a silicon on insulator (SOI) substrate is used as the Si border 11. The Si border 11 of this modification is made up of a Si substrate 111 and a SiO 2 The border includes a film 112 and a Si layer 113 .

[0044] SiO 2 The film 112 is formed on the surface of the Si substrate 111. The Si layer 113 is a SiO 2 It is formed on the surface of the film 112. The thickness of the Si layer 113 is preferably 5 nm or more and 100 μm or less.

[0045] The pellicle film 12 in this modification is also epitaxially grown on the surface 113a (surface 11a of the border 11) of the Si layer 113. In other words, the structure of the SiC crystals in the pellicle film 12 at least in the portion in contact with the surface 113a of the Si layer 113 is influenced by the Si crystals in the Si layer 113 and is changed from the structure of the bulk SiC crystals. The pellicle film 12 is in contact with the surface 113a of the Si layer 113.

[0046] In the following description, an example will be described in which the border is a Si border 11 made of a Si layer 113. However, the border may be understood to be replaced with a Si border 11 from a SOI substrate, as in a modified example.

[0047] Fig. 3 is a plan view showing the configuration of pellicle 1 in the first embodiment of the present invention when viewed from a direction perpendicular to surface 12a of pellicle film 12. In Fig. 3, Si border 11 is shown by a dotted line in order to show the shape of Si border 11, but in reality Si border 11 cannot be seen directly.

[0048] Referring to FIG. 3, each of the Si border 11, the pellicle film 12, and the through hole 13 has an arbitrary planar shape. The pellicle film 12 is supported at its outer periphery by the annular Si border 11. As a result, the mechanical strength of the pellicle film 12 is reinforced by the Si border 11. Each of the Si border 11, the pellicle film 12, and the through hole 13 may have a circular planar shape as shown in FIG. 3(a), or may have a rectangular planar shape as shown in FIG. 3(b). In FIG. 3(b), the Si border 11 has a square annular planar shape. Furthermore, as shown in FIG. 3(c), each of the Si border 11 and the pellicle film 12 may have a circular planar shape, and the through hole 13 may have a rectangular planar shape. The size of the through hole 13 is arbitrary and may be determined according to the mechanical strength required for the pellicle 1.

[0049] Next, a method for manufacturing pellicle 1 in this embodiment will be described with reference to FIGS.

[0050] 4, for example, a disk-shaped Si substrate 113 (without through-hole 13 formed therein) is prepared. Si substrate 113 is a substrate that will become Si layer 113 in FIG.

[0051] 5, next, Si is removed from central portion RG1 on rear surface 113b of Si substrate 113. Removal of Si from central portion RG1 may be performed by mechanically grinding Si from central portion RG1 of Si substrate 113. Alternatively, removal of Si from central portion RG1 may be performed by forming a photoresist on a region of rear surface 113b of Si substrate 113 excluding central portion RG1, and etching the Si from central portion RG1 using the formed photoresist as a mask.

[0052] Furthermore, in order to increase the resistance of the mask to a chemical solution used in wet etching of Si, removal of Si in the central portion RG1 may be performed by the following method.

[0053] 6, a mask layer 14 made of a silicon oxide film or a silicon nitride film is formed on the entire back surface 113b of Si substrate 113. Then, a photoresist 15 patterned into a required shape is formed on the back surface of mask layer 14.

[0054] Referring to FIG. 7, next, the mask layer 14 is patterned by wet etching using the photoresist 15 as a mask. As a result, only the outer periphery of the mask layer 14 remains. When the mask layer 14 is made of a silicon oxide film, a hydrofluoric acid solution or the like is used as a chemical for wet etching the mask layer 14. When the mask layer 14 is made of a silicon nitride film, a phosphoric acid solution or the like is used as a chemical for wet etching the mask layer 14. Next, using the patterned mask layer 14 as a mask, Si in the central portion RG1 is removed by wet etching using a chemical such as a mixed acid. Then, the photoresist 15 and the mask layer 14 are removed. The photoresist 15 may be removed before the wet etching of Si.

[0055] 4, the step of forming mask layer 14 shown in Fig. 6 may be omitted by preparing a substrate having mask layer 14 preliminarily formed on rear surface 113b of Si substrate 113. Also, as mask layer 14, a silicon oxide film or an oxide film or nitride film other than silicon oxide film may be used.

[0056] 8, as a result of removing the Si in central portion RG1, a recess 16 is formed on back surface 113b of Si substrate 113. Recess 16 has a depth not penetrating Si substrate 113, and the bottom surface of recess 16 is composed of Si of Si substrate 113. Due to the presence of recess 16, the thickness of the central portion of Si substrate 113 (the vertical length in FIG. 8) becomes thinner than the thickness of the peripheral portion of Si substrate 113.

[0057] Referring to FIG. 9, after forming the recess 16, the pellicle film 12 is formed on the surface 113a of the Si substrate 113. Specifically, the pellicle film 12 in contact with the surface 113a of the Si substrate 113 is epitaxially grown. The pellicle film 12 is formed, for example, on a base layer made of SiC obtained by carbonizing the surface 113a of the Si substrate 113 using a molecular beam epitaxy (MBE) method or a chemical vapor deposition (CVD) method. The pellicle film 12 may also be formed on the surface 113a of the Si substrate 113 using an MBE method or a CVD method. Furthermore, the pellicle film 12 may be formed only by carbonizing the surface 113a of the Si substrate 113. In addition, when forming the pellicle film 12 described above, a SiC film of the pellicle film 12 may also be formed on the side surface 113c of the Si substrate 113.

[0058] 10, next, a portion of Si substrate 113 present on bottom surface RG2 of recess 16 is removed by wet etching. During this wet etching, Si on outer periphery RG3 (portion surrounding recess 16) of back surface 113b of Si substrate 113 is also removed in addition to Si on bottom surface RG2. By employing wet etching, damage to pellicle film 12 when removing Si substrate 113 can be suppressed.

[0059] As a result of removing the Si on the bottom surface RG2, the recess 16 becomes a through hole 13. The Si substrate 113 is shaped into a Si border 11 including the through hole 13. The back surface 12b of the pellicle film 12 is exposed at the bottom surface of the through hole 13. Through the above steps, the pellicle 1 shown in FIG. 1 is completed.

[0060] The wet etching of Si on the bottom surface RG2 is performed by moving the Si substrate 113 and the pellicle film 12 relative to the chemical solution used for wet etching. The movement of the Si substrate 113 and the pellicle film 12 includes rotating the Si substrate 113 and the pellicle film 12 without changing their positions, changing the positions of the Si substrate 113 and the pellicle film 12 (in other words, moving the Si substrate 113 and the pellicle film 12), and rotating the Si substrate 113 and the pellicle film 12 while changing their positions. As the chemical solution used for wet etching of Si, for example, a mixed acid containing hydrofluoric acid and nitric acid, an aqueous solution of potassium hydroxide (KOH), etc. are used.

[0061] When an alkaline solution such as an aqueous potassium hydroxide solution is used as the chemical for wet etching of Si, the pellicle film 12 may also be etched through pinholes present at a low density in the pellicle film 12. In order to prevent the pellicle film 12 from being etched and to improve the quality of the pellicle film 12, it is preferable to use the above-mentioned mixed acid as the chemical for wet etching of Si.

[0062] The direction in which the Si substrate 113 and the pellicle film 12 are moved during Si wet etching is arbitrary. However, in order to avoid a situation in which the pellicle film 12 is damaged due to pressure from the chemical solution while the Si substrate 113 and the pellicle film 12 are being moved, it is preferable to move the Si substrate 113 and the pellicle film 12 in a direction within a plane parallel to the surface 12a of the pellicle film 12 (plane PL in FIGS. 11 to 13), as in the following first to third methods.

[0063] 11 to 13 are diagrams showing the first to third methods of wet etching of Si in the first embodiment of the present invention. In the explanation of Fig. 11 to Fig. 13, the structure immediately before the wet etching of Si is referred to as intermediate body 2. In this embodiment, the structure immediately after the process of Fig. 9 corresponds to intermediate body 2, and in the second embodiment described later, the structure immediately after the process of Fig. 20 corresponds to intermediate body 2.

[0064] 11, the first method is a method of removing Si by spin etching. In the first method, the intermediate body 2 is fixed to a fixing stand HP so that the back surface 113b of the Si substrate 113 faces upward. Then, as indicated by an arrow AR1, the fixing stand HP is rotated about a rotation axis extending in a direction perpendicular to the back surface 113b. In this manner, while the intermediate body 2 is rotated without changing its position, a chemical solution MA (etchant) used for wet etching is injected into the back surface 113b of the Si substrate 113. The rotation speed of the fixing stand HP is set to, for example, about 500 to 1500 rpm.

[0065] 12, in the second method, a plurality of intermediate bodies 2 are fixed in an upright state to a fixing stage HP. Then, the plurality of intermediate bodies 2 are immersed in a chemical solution MA filled inside a reaction vessel CS, and the intermediate bodies 2 and the fixing stage HP are rotated while changing the position of the intermediate bodies 2 as indicated by an arrow AR2 within a plane PL parallel to the surface 12a of the pellicle membrane 12.

[0066] 13, in the third method, the intermediate 2 is fixed to a fixing stage HP so that the back surface 113b of the Si substrate 113 faces upward. Then, the intermediate 2 is immersed in the chemical solution MA filled inside the reaction vessel CS, and the intermediate 2 and the fixing stage HP are moved back and forth in a straight line as indicated by the arrow AR3 within a plane PL parallel to the front surface 12a of the pellicle film 12.

[0067] Fig. 14 is an enlarged view of part A in pellicle 1 shown in Fig. 1. Note that in Fig. 14, the amount of change in width of Si substrate 113 is exaggerated more than in reality.

[0068] 14, a mixed acid containing hydrofluoric acid and nitric acid has the effect of isotropically etching Si. Therefore, when Si is wet-etched using a mixed acid containing hydrofluoric acid and nitric acid as a chemical solution, the width d of Si substrate 113 (the distance between the inner and outer circumferential surfaces of Si substrate 113) decreases with increasing distance from pellicle film 12 (from pellicle film 12 toward rear surface 113b of Si substrate 113) as a trace.

[0069] As a modification of the manufacturing method of this embodiment, the recesses 16 may be formed in the Si substrate 113 after the pellicle film 12 is formed on the surface 113a of the Si substrate 113.

[0070] Moreover, the through-hole 13 may be formed only by wet etching of Si without forming the recess 16.

[0071] Also, instead of epitaxially growing the pellicle film 12 on the surface 113a of the Si substrate 113, the Si substrate 113 and a bulk SiC substrate may be bonded together, and then the SiC substrate may be thinned to form the pellicle film 12.

[0072] Furthermore, it is sufficient that the pellicle film 12 is formed on the surface 113a side of the Si substrate 113, and any film may be formed between the pellicle film 12 and the Si substrate 113.

[0073] Furthermore, a film made of a material other than SiC, such as a graphene film, may be formed on the surface 12a of the pellicle film 12.

[0074] Next, the effects of this embodiment will be described.

[0075] 15 is a diagram for explaining the effect of the first embodiment of the present invention. Note that in FIG. 15, the deformation of the border 11 is emphasized more than in the actual case.

[0076] 15(a), in pellicle 1, pellicle film 12 receives tensile stress F1 from Si border 11, and Si border 11 receives compressive stress F2 from pellicle film 12. Pellicle film 12 is kept in a state of no slackness by tensile stress F1. The inventors of the present application have found that the tensile stress F1 (approximately 300 MPa) received by conventional pellicle film 12 from Si border 11 is too large, which causes cracks in pellicle film 12.

[0077] 15(b), the present inventors have focused on the fact that the Young's modulus of the Si layer decreases with an increase in the B concentration in the Si layer (see Non-Patent Document 1). According to this embodiment, since the Si layer 113 contains B, the Young's modulus of the Si layer 113 decreases compared to when the Si layer 113 does not contain B, and the Si border 11 becomes more likely to deform due to the compressive stress F2. As a result, the tensile stress F1 that the pellicle film 12 receives from the Si border 11 is alleviated, and cracking of the pellicle film 12 can be suppressed.

[0078] In addition, the thermal expansion coefficient of SiC is larger than that of Si. Therefore, when the temperature of the pellicle 1 changes, the Si border 11 and the pellicle film 12 each expand or compress, and the magnitude of the tensile stress F1 changes. The inventors of the present application have found that the fluctuation of the tensile stress F1 due to the temperature change of the pellicle 1 is also a cause of cracking of the pellicle film 12.

[0079] In this embodiment, since the Si layer 113 contains B, the Si border 11 is easily deformed by the compressive stress F2. As a result, the fluctuation in the magnitude of the tensile stress F1 due to the temperature change of the pellicle 1 is mitigated by the deformation of the Si layer 113, and the cracking of the pellicle film 12 can be suppressed.

[0080] 15(a), when pellicle film 12 is epitaxially grown on surface 113a of Si layer 113, the Si crystals of Si layer 113, which is the underlayer, apply a tensile stress F1, which is a force for matching the Si crystals with the SiC crystals in pellicle film 12. This is because the lattice constant of SiC is smaller than that of Si.

[0081] 15(b), according to the present embodiment, the Young's modulus of Si layer 113 is reduced, and therefore the magnitude of tensile stress F1 applied by the Si crystals of Si layer 113 to the SiC crystals in pellicle film 12 is reduced. As a result, cracking of pellicle film 12 can be suppressed.

[0082] Furthermore, by moving the Si substrate 113 and the pellicle film 12 relative to the wet etching solution during wet etching of the Si layer 113, it is possible to prevent the pellicle film 12 from cracking or peeling off from the Si substrate 113 during wet etching of the Si substrate 113, thereby making it possible to reduce the thickness of the pellicle film 12 in the pellicle 1.

[0083] The present inventors have noticed that during the manufacture of the pellicle 1, cracks may occur in the Si substrate 113 or the pellicle film 12 may peel off from the Si substrate 113 during wet etching of the Si substrate 113 (during immersion of the Si substrate 113 in the chemical solution). The present inventors have found that this is caused by the chemical solution remaining locally on the reaction surface of the Si substrate 113 (the surface of the portion of the back surface 113b of the Si substrate 113 that reacts with the chemical solution), which makes the etching rate of Si non-uniform and causes roughness on the reaction surface of the Si substrate 113. The present inventors have also found that when a mixed acid is used as the chemical solution for wet etching, large bubbles generated by the reaction between the chemical solution and Si remain locally on the reaction surface of the Si substrate 113, and these bubbles locally hinder the reaction of the reaction surface of the Si substrate 113 with the chemical solution, causing roughness on the reaction surface of the Si substrate 113.

[0084] When the pellicle film 12 is relatively thick, the mechanical strength of the pellicle film 12 itself is high, so that the roughness of the reaction surface of the Si substrate 113 does not have a significant adverse effect on the pellicle film 12. However, when the pellicle film 12 is relatively thin (for example, when the thickness is 10 μm or less, specifically, when it is a thin film (a thickness of about a few μm) or an extremely thin film (a thickness of the order of 100 nm or less), the roughness of the reaction surface of the Si substrate 113 has an adverse effect on the pellicle film 12. In other words, the roughness of the reaction surface of the Si substrate 113 applies non-uniform stress to the pellicle film 12, leading to a situation in which the pellicle film 12 cracks or the pellicle film 12 peels off from the Si substrate 113 during Si etching.

[0085] Therefore, in this embodiment, when wet etching the Si substrate 113, the Si substrate 113 and the pellicle film 12 are moved relative to the wet etching chemical, thereby preventing the chemical or bubbles from staying locally on the reaction surface of the Si substrate 113 after the reaction, and preventing roughening of the reaction surface of the Si substrate 113. As a result, it is possible to prevent non-uniform stress from being applied to the pellicle film 12, and the thickness of the pellicle film 12 can be reduced.

[0086] In particular, when a method of removing Si by spin etching (first method shown in FIG. 11) is adopted as the method of wet etching of Si, the pellicle film 12 is exposed to the chemical solution during wet etching only while the back surface 12b of the pellicle film 12 is exposed to the bottom of the recess 16. Furthermore, the front surface 12a of the pellicle film 12 is not exposed to the chemical solution during wet etching. Therefore, damage to the pellicle film 12 caused by the chemical solution can be kept to a minimum.

[0087] In addition, by using a mixed acid as the chemical for wet etching of Si, it is possible to prevent damage to the pellicle film 12 caused by the chemical. As a result, it is possible to improve the yield of the pellicle film 12, and it is possible to form the pellicle film 12 in a large area.

[0088] [Second embodiment]

[0089] 16 is a cross-sectional view showing the configuration of a pellicle 1 in the second embodiment of the present invention. Note that Fig. 16 is a cross-sectional view taken along a plane perpendicular to a surface 12a of a pellicle film 12.

[0090] With reference to FIG. 16, pellicle 1 in this embodiment differs from the pellicle in the first embodiment in that it further includes adhesive film 17 (an example of an adhesive film).

[0091] The adhesive film 17 is provided between the Si border 11 and the pellicle film 12, and bonds the Si border 11 and the pellicle film 12. The adhesive film 17 is made of any material, such as an acrylic resin adhesive, an epoxy resin adhesive, a polyimide resin adhesive, a silicone resin adhesive, an inorganic adhesive, a double-sided adhesive tape, a silicone resin adhesive, an acrylic adhesive, or a polyolefin adhesive.

[0092] Next, a method for manufacturing pellicle 1 in this embodiment will be described with reference to FIGS.

[0093] 17, for example, a disk-shaped Si substrate (sacrificial substrate) 21 is prepared. A (111) plane is exposed on a back surface 21a of the Si substrate 21. A (100) plane or a (110) plane may be exposed on the back surface 21a of the Si substrate 21.

[0094] 18, next, a pellicle film 12 is formed on the rear surface 21a of the Si substrate 21. The pellicle film 12 is formed, for example, on a base layer made of SiC obtained by carbonizing the rear surface 21a of the Si substrate 21 by using an MBE method, a CVD method, or the like. The pellicle film 12 may also be formed by only carbonizing the rear surface 21a of the Si substrate 21. Furthermore, the pellicle film 12 may also be formed on the rear surface 21a of the Si substrate 21 by using an MBE method, a CVD method, or the like.

[0095] Any substrate can be used as the base substrate for the pellicle film 12, but it is preferable to determine the substrate in consideration of the crystallinity of the upper layer of the pellicle film 12 and the ease of removal in a later process. Specifically, a quartz substrate may be used as the base substrate for the pellicle film 12 instead of the Si substrate 21.

[0096] 19, next, for example, a disk-shaped Si substrate 113 (without through-holes 13 formed therein) is prepared. Si substrate 113 contains B. B is implanted into Si substrate 113 by a method such as a thermal diffusion method or an ion implantation method.

[0097] Then, a through hole 13 is formed in the Si substrate 113 to fabricate a Si border 11 made of the Si substrate 113. The Si border 11 has an annular planar shape surrounding the through hole 13. The method for forming the through hole 13 is arbitrary, and methods such as mechanical grinding and etching may be used.

[0098] 20, next, the back surface 12b of the pellicle film 12 and the Si border 11 are bonded together using an adhesive. The back surface 12b of the pellicle film 12 is the main surface opposite to the main surface (front surface 12a) of the pellicle film 12 on which the Si substrate 21 is present. An adhesive film 17 is formed between the pellicle film 12 and the Si border 11. As a result, an intermediate 2 including the Si substrate 21, the pellicle film 12, the Si border 11, and the adhesive film 17 is obtained.

[0099] 21, the Si substrate 21 is then removed from the intermediate body 2. This exposes the entire surface 12a of the pellicle film 12. When removing the Si substrate 21, it is preferable to first remove the Si by a method that has a relatively fast Si removal rate (e.g., mechanical polishing) to reduce the thickness of the Si substrate 21 to an arbitrary thickness, and then remove the Si by a method that has a relatively slow Si removal rate (e.g., wet etching) to completely remove the Si substrate 21. Through the above steps, the pellicle 1 shown in FIG. 16 is completed.

[0100] The Si wet etching is preferably performed by moving the intermediate 2 relative to the chemical solution. The Si wet etching is preferably performed by any one of the first to third methods (FIGS. 11 to 13) of the Si wet etching in the first embodiment. However, the target of the wet etching is the Si substrate 21, not the Si substrate 113. For this reason, when the first method (FIG. 11) is used, the intermediate 2 is fixed to the fixing table HP so that the surface 21b of the Si substrate 21 faces upward. Then, while the intermediate 2 is rotated without changing the position of the intermediate 2, the chemical solution MA is injected into the surface 21b of the Si substrate 21. Also, when the third method (FIG. 13) is used, the intermediate 2 is fixed to the fixing table HP so that the surface 21b of the Si substrate 21 faces upward. Then, the intermediate 2 and the fixing table HP are moved back and forth on a straight line.

[0101] Other than as described above, the configuration and manufacturing method of pellicle 1 are the same as those of the pellicle of the first embodiment, and therefore description thereof will not be repeated.

[0102] Next, the effects of this embodiment will be described.

[0103] In this embodiment, the same effect as in the first embodiment can be obtained. That is, as shown in Fig. 15(b), since the Si layer 113 contains B, the Si border 11 is easily deformed by the compressive stress F2. As a result, the tensile stress F1 that the pellicle film 12 receives from the Si border 11 is alleviated, and cracking of the pellicle film 12 can be suppressed.

[0104] Moreover, according to this embodiment, since the Si substrate 21 is completely removed after the pellicle film 12 is formed, the process for etching a part of the Si substrate 21 (such as the process of patterning and removing the photoresist or hard mask) can be omitted, and as a result, the manufacturing process can be simplified and the manufacturing cost of the pellicle can be reduced. Moreover, since the pellicle film 12 is supported by the Si border 11, the pellicle film 12 can be made thin while maintaining its mechanical strength.

[0105] Furthermore, by wet-etching the Si substrate 21 by moving the intermediate body 2 relative to the wet etching solution, it is possible to prevent the pellicle film 12 from cracking or peeling off from the Si substrate 21 during the wet etching of the Si substrate 21, thereby making it possible to reduce the thickness of the pellicle film 12 in the pellicle 1.

[0106] [Example]

[0107] The inventors of the present application confirmed the effect of improving the mechanical strength of the pellicle film by including in the border a Si layer containing B. Specifically, the following samples A to D were fabricated, and the yield rate of each of the samples A to D was investigated.

[0108] Sample A (example of the present invention): The pellicle shown in Fig. 1 was produced using the manufacturing method shown in the first embodiment. The Si layer used had a B concentration adjusted so that the resistivity of the Si layer was in the range of more than 0 and 0.005 Ω cm or less.

[0109] Sample B (example of the present invention): The B concentration of the Si layer was adjusted so that the resistivity of the Si layer was in the range of more than 0.005 Ω cm and not more than 0.02 Ω cm. Other than this, pellicle 1 was produced by the same manufacturing method as sample A.

[0110] Sample C (example of the present invention): The B concentration of the Si layer was adjusted so that the resistivity of the Si layer was in the range of 1 Ω cm to 100 Ω cm. Other than this, pellicle 1 was produced by the same manufacturing method as sample A.

[0111] Sample D (Comparative Example): The Si layer used was not doped with B. Other than this, pellicle 1 was produced by the same production method as sample A.

[0112] FIG. 22 is a diagram showing the yield rates of each of the samples A to D in one embodiment of the present invention.

[0113] 22, the yield rate of sample A was 100%, the yield rate of sample B was 63%, the yield rate of sample C was 30%, and the yield rate of sample D was 15%. The decrease in yield rate was mostly caused by damage to the pellicle film during the formation of through-holes in the Si layer by wet etching of the Si layer (during the process shown in FIG. 10).

[0114] These results suggest that as the B concentration in the Si border increases, the stress applied to the pellicle film from the Si border is alleviated, suppressing damage to the pellicle film.

[0115] [others]

[0116] The pellicle film may be made of a material other than SiC, such as Si, SiN, or C (graphite, graphene, diamond-like carbon (DLC), or amorphous carbon, etc.). However, a pellicle film made of SiC is particularly preferable as a pellicle film because it can improve the transmittance and resistance to exposure light of the pellicle film while preventing cracking of the pellicle film when the pellicle film is made thin. In addition, the shape of the border is arbitrary.

[0117] The configurations and manufacturing methods of the above-mentioned embodiment, modifications, and examples can be combined as appropriate. For example, the planar shape of pellicle 1 in the second embodiment may be as shown in FIG.

[0118] The above-mentioned embodiments, modifications, and examples should be considered as illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0119] 1 Pellicle (an example of a pellicle) 2. Intermediates 11 Si (silicon) border (an example of a border) 11a Si border surface 11b Back side of Si border 11c Si Border Side 12 Pellicle membrane (an example of a pellicle membrane) 12a Surface of pellicle membrane 12b Back side of pellicle membrane 12c Side of pellicle membrane 13 Through hole in Si border (example of through hole) 14 Mask Layer 15 Photoresist 16 Recessed portion of Si substrate 17 Adhesive film (example of adhesive film) 21. Silicon substrate 21a Backside of Si substrate 21b Surface of Si substrate 111 Si substrate 112SiO 2 (Silicon oxide) film 113 Si layer or Si substrate (an example of a Si layer) 113a Surface of Si layer or Si substrate 113b Backside of Si layer or Si substrate 113c Side of Si layer or Si substrate CS Reaction Vessel F1, F3 Tensile stress F2 Compressive stress HP fixed stand MA Chemical Solution PL: Plane parallel to the surface of the pellicle membrane RG1 Center of the back surface of the Si substrate RG2: Bottom surface of recess in Si substrate RG3: Outer periphery of the back side of the Si substrate

Claims

1. a border including a Si layer containing B; A pellicle film formed on one main surface side of the Si layer, The Si layer has a P-type conductivity and includes Si crystals.

2. The pellicle of claim 1 , wherein the resistivity of the Si layer is greater than 0 and less than or equal to 0.02 Ω·cm.

3. The pellicle of claim 1 or 2, wherein the pellicle membrane has a thickness of 10 nm or more and 50 nm or less.

4. The pellicle according to any one of claims 1 to 3, further comprising an adhesive film that bonds the pellicle membrane and the Si layer.

5. The pellicle according to any one of claims 1 to 4, wherein the pellicle membrane is made of SiC.

6. The pellicle according to any one of claims 1 to 5, wherein the border includes a through hole, and the pellicle membrane is exposed at a bottom surface of the through hole.

7. preparing a Si layer containing B, the Si layer having a P-type conductivity and including Si crystals; and forming a pellicle film on one main surface side of the Si layer.

8. A method for manufacturing a pellicle as described in claim 7, further comprising a step of creating a border including the Si layer by forming a through hole in the Si layer, the through hole exposing the pellicle membrane at the bottom surface.

9. 9. The method of claim 7, wherein the pellicle membrane is made of SiC. method.

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