Diaphragm and preparation method thereof

Abstract

The embodiment of the invention provides a diaphragm and a preparation method thereof, the diaphragm comprises a metal film layer, a silicon substrate, a hard mask layer and a diaphragm aperture which are arranged in sequence, the silicon substrate is provided with a first surface and an opposite second surface, the first surface is provided with a first aperture structure, and the second surface is provided with a second aperture structure. The length of the second hole structure on the second surface is determined by the beam spot diameter of the charged particle beam; the metal film layer has a third hole structure, and the hard mask layer has a fourth hole structure; and the diaphragm hole is formed by communicating the third hole structure, the first hole structure, the second hole structure and the fourth hole structure. According to the embodiment of the invention, the length of the second hole structure on the second surface is determined based on the beam spot diameter of the charged particle beam, and a method of etching the second hole structure on the second surface of the deposited silicon substrate and then etching the first hole structure on the first surface is adopted, so that the size precision and consistency of the submicron diaphragm hole are improved.

Description

Technical Field

[0001] This application relates to the field of optical element technology, and in particular to an aperture and its fabrication method. Background Technology

[0002] An aperture is a component in an optical system that does not have imaging capabilities but can limit the propagation of a light beam through its physical structure. Its core function is to optimize imaging quality by controlling the range of light beam propagation.

[0003] Currently, metals such as molybdenum, platinum, tantalum, and gold can be used as raw materials to fabricate apertures through processes such as machining, wet etching, or electrical discharge machining. However, due to limitations in traditional fabrication processes, and the fact that metal materials are prone to deformation when heated during processing and use, this fabrication method makes it difficult to ensure the dimensional accuracy and consistency of submicron aperture holes.

[0004] Therefore, there is an urgent need for a solution to address the aforementioned technical problems. Summary of the Invention

[0005] Based on the above problems, this application provides an aperture and its preparation method, aiming to improve the dimensional accuracy and consistency of submicron aperture holes.

[0006] The embodiments of this application disclose the following technical solutions:

[0007] Firstly, this application provides an aperture, which includes: a metal film layer, a silicon substrate, a hard mask layer, and an aperture hole arranged sequentially; the silicon substrate has a first surface and an opposite second surface, the first surface has a first aperture structure, the second surface has a second aperture structure, and the length of the second aperture structure on the second surface is determined by the beam spot diameter of the charged particle beam; the metal film layer has a third aperture structure, and the hard mask layer has a fourth aperture structure; the aperture hole is formed by the connection of the third aperture structure, the first aperture structure, the second aperture structure, and the fourth aperture structure.

[0008] In one possible implementation, the length of the second aperture structure on the second surface is determined by the beam spot diameter of the charged particle beam, including:

[0009] The length of the second hole structure on the second surface is greater than or equal to The beam spot diameter is times that of the beam spot diameter, and is less than or equal to the beam spot diameter.

[0010] In one possible implementation, the thickness of the silicon substrate is determined based on the length of the second hole structure on the second surface and the energy of the charged particle beam.

[0011] In one possible implementation, the thickness of the silicon substrate is determined based on the length of the second aperture structure on the second surface and the energy of the charged particle beam, including:

[0012] The first depth of the second hole structure is determined based on the length of the second hole structure on the second surface;

[0013] The thickness of the silicon substrate is determined based on the first depth and the energy of the charged particle beam.

[0014] In one possible implementation, determining the thickness of the silicon substrate based on the first depth and the energy of the charged particle beam includes:

[0015] The second depth of the first hole structure is determined based on the energy of the charged particle beam and the first coefficient.

[0016] The sum of the first depth and the second depth is determined as the thickness of the silicon substrate.

[0017] In one possible implementation, the second hole structure is a pyramid-shaped three-dimensional structure obtained by anisotropic wet etching of the second surface of the silicon substrate.

[0018] Second aspect: This application provides a method for preparing an aperture, comprising:

[0019] A hard mask layer is deposited on the silicon substrate to obtain the deposited silicon substrate.

[0020] A window region is photolithographically formed on the second surface of the deposited silicon substrate using a hard mask layer;

[0021] The second surface of the silicon substrate corresponding to the window region is etched using KOH or TMAH solution until the depth of the second hole structure formed by etching reaches the first depth, at which point the etching is stopped.

[0022] An opening region is photolithographically formed on the first surface of the deposited silicon substrate using a hard mask layer, and the center of the opening region is on a straight line with the center of the window region.

[0023] The first surface of the silicon substrate corresponding to the opening region is etched using deep reactive ion etching technology until the depth of the first hole structure formed by etching reaches the third depth, at which point the etching is stopped. The first hole structure is connected to the second hole structure.

[0024] The hard mask layer on the first surface of the silicon substrate after deep reactive ion etching is removed, and a metal film is formed on the first surface of the silicon substrate to obtain an aperture.

[0025] In one possible implementation, before etching the second surface of the silicon substrate corresponding to the window region using KOH or TMAH solution, the method further includes:

[0026] The length of the second aperture structure on the second surface is determined based on the beam spot diameter of the charged particle beam, and the length of the second aperture structure on the second surface corresponds to the side length of the window region.

[0027] Wherein, the length of the second hole structure on the second surface is greater than or equal to The beam spot diameter is times that of the beam spot diameter, and is less than or equal to the beam spot diameter.

[0028] In one possible implementation, the process of continuing until the depth of the second hole structure formed by etching reaches the first depth further includes:

[0029] Based on the length of the second hole structure on the second surface, a first depth is determined, wherein the first depth is the product of half the side length of the window region and the first angle tangent.

[0030] In one possible implementation, before depositing a hard mask layer on the silicon substrate to obtain the deposited silicon substrate, the method further includes:

[0031] The second depth of the first hole structure is determined based on the energy of the charged particle beam and the first coefficient.

[0032] The thickness of the silicon substrate is determined based on the sum of the second depth and the first depth.

[0033] In one possible implementation, the etching of the first surface of the silicon substrate corresponding to the opening region using deep reactive ion etching technology until the depth of the first hole structure formed by etching reaches a third depth includes:

[0034] The third depth is determined based on the second depth, the length of the opening region, and the first angle, wherein the third depth is the sum of half the length of the opening region and the tangent of the first angle, plus the second depth.

[0035] In one possible implementation, before photolithographically etching the window region on the hard mask layer on the second surface of the deposited silicon substrate, the method further includes:

[0036] Based on the beam spot diameter of the charged particle beam and the aperture characteristic information, the aperture spacing and layout of multiple first aperture structures are determined.

[0037] The hard mask layer on the second surface of the deposited silicon substrate is photolithographically etched to create a window region, including:

[0038] Based on the hole spacing and layout of the plurality of first hole structures, a plurality of window regions are photolithographically formed on the hard mask layer on the second surface of the deposited silicon substrate.

[0039] Third aspect: Embodiments of this application provide a system for fabricating an aperture, comprising:

[0040] The system includes a deposition module, a first photolithography module, a first etching module, a second photolithography module, a second etching module, and a removal module.

[0041] The deposition module is used to deposit a hard mask layer on a silicon substrate to obtain a deposited silicon substrate;

[0042] The first photolithography module is used to photolithographically create a window region on the hard mask layer on the second surface of the deposited silicon substrate;

[0043] The first etching module is used to etch the second surface of the silicon substrate corresponding to the window area using KOH or TMAH solution until the depth of the second hole structure formed by etching reaches the first depth, and then the etching is stopped.

[0044] The second photolithography module is used to photolithographically create an opening region on the hard mask layer of the first surface of the deposited silicon substrate, wherein the center of the opening region and the center of the window region are on a straight line.

[0045] The second etching module is used to etch the first surface of the silicon substrate corresponding to the opening region using deep reactive ion etching technology until the depth of the first hole structure formed by etching reaches the third depth, and then the etching stops, wherein the first hole structure is connected to the second hole structure.

[0046] The removal module is used to remove the hard mask layer on the first surface of the silicon substrate after deep reactive ion etching, and to set a metal film on the first surface of the silicon substrate to obtain an aperture.

[0047] Fourth aspect: Embodiments of this application provide a scanning electron microscope, including an aperture as described in the first aspect above.

[0048] Compared with the prior art, the embodiments of this application have the following beneficial effects:

[0049] In this embodiment, a single-crystal silicon wafer is used as the substrate, avoiding the problem of easy deformation due to heat during processing and use of metal materials. Based on this, the length of the second aperture structure on the second surface is determined according to the beam spot diameter of the charged particle beam. Furthermore, a method is adopted where the second aperture structure is etched first on the second surface of the deposited silicon substrate, followed by the etching of the first aperture structure on the first surface, thereby improving the dimensional accuracy and consistency of the submicron-level aperture. Attached Figure Description

[0050] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0051] Figure 1 A schematic diagram of an aperture provided for an embodiment of this application;

[0052] Figure 2 This is a cross-sectional schematic diagram of a second hole structure provided in an embodiment of this application;

[0053] Figure 3 A schematic diagram illustrating the determination of the thickness of a single-crystal silicon wafer, provided as an embodiment of this application;

[0054] Figure 4 A schematic diagram of a second hole structure provided in an embodiment of this application;

[0055] Figure 5 A schematic diagram of a single-row aperture arrangement provided in an embodiment of this application;

[0056] Figure 6 A schematic diagram of a multi-row aperture layout provided in an embodiment of this application;

[0057] Figure 7 A schematic diagram of an annular aperture provided in an embodiment of this application;

[0058] Figure 8 A schematic diagram illustrating the determination of hole spacing provided in an embodiment of this application;

[0059] Figure 9 A flowchart illustrating a method for fabricating an aperture according to an embodiment of this application;

[0060] Figure 10 A schematic diagram illustrating the determination of a third depth, provided as an embodiment of this application;

[0061] Figure 11 A flowchart illustrating another method for fabricating an aperture according to an embodiment of this application;

[0062] Figure 12 A schematic diagram illustrating a method for fabricating an aperture according to an embodiment of this application;

[0063] Figure 13 This is a schematic diagram of the structure of an aperture fabrication system provided in an embodiment of this application. Detailed Implementation

[0064] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. The terminology used in the following embodiments is for the purpose of describing specific embodiments only and is not intended to be a limitation of this application. As used in the specification and appended claims of this application, the singular expressions "a," "an," "the," "the," "the," and "this" are intended to also include expressions such as "one or more," unless the context clearly indicates otherwise.

[0065] It should be noted that in the description of the embodiments of this application, the terms "first" and "second" are used only for the purpose of distinguishing descriptions and should not be construed as indicating or implying relative importance, nor should they be construed as indicating or implying order.

[0066] Currently, metals such as molybdenum, platinum, tantalum, and gold can be used as raw materials to fabricate apertures through processes such as machining, wet etching, or electrical discharge machining. However, due to limitations in traditional fabrication processes, and the fact that metal materials are prone to deformation when heated during processing and use, this fabrication method makes it difficult to ensure the dimensional accuracy and consistency of submicron aperture holes.

[0067] Based on this, this application provides an aperture and its fabrication method. A hard mask layer is deposited on a silicon substrate to obtain a deposited silicon substrate. A window region is photolithographically etched on the hard mask layer on the second surface of the deposited silicon substrate. The second surface of the silicon substrate corresponding to the window region is etched using KOH or TMAH solution until the depth of the second hole structure formed by etching reaches a first depth, at which point etching is stopped. An opening region is photolithographically etched on the hard mask layer on the first surface of the deposited silicon substrate, the center of the opening region and the center of the window region being on a straight line. The first surface of the silicon substrate corresponding to the opening region is etched using deep reactive ion etching technology until the depth of the first hole structure formed by etching reaches a third depth, at which point etching is stopped. The first hole structure is connected to the second hole structure. The hard mask layer on the first surface of the silicon substrate after deep reactive ion etching is removed, and a metal film is deposited on the first surface of the silicon substrate to obtain the aperture.

[0068] The aperture includes a metal film layer, a silicon substrate, a hard mask layer, and an aperture hole arranged sequentially. The silicon substrate has a first surface and an opposite second surface. The first surface has a first aperture structure, and the second surface has a second aperture structure. The length of the second aperture structure on the second surface is determined by the beam spot diameter of the charged particle beam. The metal film layer has a third aperture structure, and the hard mask layer has a fourth aperture structure. The aperture hole is formed by connecting the third aperture structure, the first aperture structure, the second aperture structure, and the fourth aperture structure.

[0069] In this embodiment, a single-crystal silicon wafer is used as the substrate, avoiding the problem of easy deformation due to heat during processing and use of metal materials. Based on this, the length of the second aperture structure on the second surface is determined according to the beam spot diameter of the charged particle beam. Furthermore, a method is adopted where the second aperture structure is etched first on the second surface of the deposited silicon substrate, followed by the etching of the first aperture structure on the first surface, thereby improving the dimensional accuracy and consistency of the submicron-level aperture.

[0070] like Figure 1 As shown, this figure is a schematic diagram of an aperture provided in an embodiment of this application.

[0071] The aperture includes a metal film layer 101, a silicon substrate 102, a hard mask layer 103, and an aperture hole 104 arranged sequentially.

[0072] The silicon substrate 102 has a first surface and an opposite second surface, the first surface having a first hole structure and the second surface having a second hole structure.

[0073] The first hole structure has a circular cross-section, and its diameter can be set according to requirements. For example, the diameter (D1) of the first hole structure is less than or equal to 20μm.

[0074] The length of the second hole structure on the second surface is greater than or equal to 1 / The beam spot diameter is twice that of the charged particle beam, and is less than or equal to that beam spot diameter, to ensure that the aperture has sufficient mechanical strength.

[0075] like Figure 2 As shown, this figure is a cross-sectional schematic diagram of a second hole structure provided in an embodiment of this application. The second hole structure is a square 2100 on the second surface. The center point of the square 2100 can be the center of the charged particle beam spot 2101, and the diameter of the charged particle beam spot can be represented as D0. The length of the second hole structure on the second surface can be represented as D2, where D0≤D2≤D0 / This is to ensure that the aperture has sufficient mechanical strength.

[0076] The thickness of the silicon substrate 102 is determined based on the length of the second hole structure on the second surface and the energy of the charged particle beam, such as... Figure 3 As shown in the figure, this figure is a schematic diagram of determining the thickness of a single-crystal silicon wafer according to an embodiment of this application.

[0077] For example, in this embodiment of the application, the second hole structure can be a pyramid-shaped three-dimensional structure obtained by anisotropic wet etching of the second surface of the silicon substrate 102, such as... Figure 4 As shown in the figure, this figure is a schematic diagram of a second hole structure provided in an embodiment of this application.

[0078] Based on this, the first depth of the second hole structure can be determined based on the length of the second hole structure on the second surface; based on the first depth and the energy of the charged particle beam, the thickness of the silicon substrate 102 is determined as shown in equations (1)-(3):

[0079] (1)

[0080] (2)

[0081] T0 = ​​T1 + T2 (3)

[0082] Where D2 represents the length of the second hole structure on the second surface; θ represents the first angle, which is the angle of the bottom corner of the second hole structure, for example, θ is 54.74°; T2 represents the first depth of the second hole structure; a represents the first coefficient, for example, a is 0.038; E represents the energy of the charged particle beam; T1 represents the second depth of the first hole structure; T0 represents the thickness of the silicon substrate 102.

[0083] It is understood that the values ​​of the first angle and the first coefficient are not specifically limited in the embodiments of this application, and can be determined based on the actual situation.

[0084] In this embodiment, the metal film layer 101 has a third pore structure, and the hard mask layer 103 has a fourth pore structure.

[0085] For example, the metal film layer 101 includes an adhesive layer and a surface conductive layer, and the cross-sectional dimensions of the third hole structure are the same as those of the first hole structure.

[0086] The adhesive layer can be made of titanium (Ti) or chromium (Cr), with a thickness ranging from 20nm to 100nm; the surface conductive layer can be made of gold (Au), platinum (Pt), or molybdenum (Mo), with a thickness ranging from 100nm to 300nm.

[0087] The cross-sectional dimensions of the fourth hole structure of the hard mask layer 103 are the same as those of the second hole structure. The hard mask layer 103 can be a layer of silicon dioxide (SiO2) with a thickness range of 100nm-500nm grown by thermal oxidation, or a layer of silicon nitride (Si3N4) with a thickness range of 100nm-200nm generated by low-pressure chemical vapor deposition (LPCVD).

[0088] In this embodiment of the application, the aperture 104 is formed by the interconnection of the third aperture structure, the first aperture structure, the second aperture structure, and the fourth aperture structure, as shown below. Figure 1 As shown.

[0089] In one possible implementation, the aperture provided in this application embodiment may include one or more aperture holes 104. When the aperture includes multiple aperture holes 104, the aperture spacing and layout of the multiple first hole structures may be determined by the beam spot diameter of the charged particle beam and the aperture characteristic information.

[0090] The aperture characteristic information may include, but is not limited to, the electronic device structure in which the aperture is applied, the application scenario of the aperture, the size of the aperture aperture 104, the mechanical strength of the aperture, and the energy of the electron beam corresponding to the aperture.

[0091] For example, the layout of the first aperture structure on the aperture plate includes, but is not limited to, a single-row, multi-row, or ring-shaped layout, such as... Figures 5-7 As shown, the figures are schematic diagrams of a single-row layout aperture 104, a multi-row layout aperture 104, and a ring layout aperture 104 provided in the embodiments of this application.

[0092] like Figure 8 As shown in the figure, this figure is a schematic diagram of determining the aperture spacing provided in an embodiment of this application. Taking the single-row layout of aperture 104 as an example, when the aperture spacing (the distance between the centers of adjacent apertures) is greater than or equal to D0, it can effectively prevent the adjacent first aperture structure from being damaged by the charged particle beam, while maximizing the utilization of the effective area on the aperture plate, thereby reducing the frequency of aperture plate replacement and extending the normal operation time of the charged particle beam equipment.

[0093] It is understood that the number of rows of the first hole structure and the number of first hole structures included in each row are not specifically limited in the embodiments of this application; the figures are merely examples.

[0094] The aperture provided in this embodiment has submicron-level dimensional accuracy and consistency. Furthermore, when the aperture includes multiple aperture holes, since the hole spacing and layout of the multiple first hole structures are determined by the beam spot diameter of the charged particle beam and the aperture characteristic information, it can effectively avoid damage to adjacent first hole structures by the charged particle beam, maximize the utilization of the effective area on the aperture plate, reduce the frequency of aperture plate replacement, and extend the normal operation time of the charged particle beam device.

[0095] The following describes a method for preparing an aperture according to an embodiment of this application, with reference to the accompanying drawings.

[0096] like Figure 9 As shown, this figure is a flowchart of a method for preparing an aperture according to an embodiment of this application, including S901-S906.

[0097] S901. A hard mask layer is deposited on the silicon substrate to obtain the deposited silicon substrate.

[0098] In this embodiment, using a single-crystal silicon wafer as the substrate avoids the problem of easy deformation due to heat during processing and use of metal materials.

[0099] Before depositing a hard mask layer on a silicon substrate to obtain the deposited silicon substrate, the second depth of the first hole structure can be determined based on the energy of the charged particle beam and a first coefficient; the thickness of the silicon substrate can be determined based on the sum of the second depth and the first depth.

[0100] For example, when using a single-crystal silicon wafer with a crystal orientation of (100) as the substrate for fabricating the aperture, and determining that potassium hydroxide (KOH) solution or tetramethylammonium hydroxide (TMAH) solution is subsequently used as the etching solution, the first depth of the second hole structure can be determined based on the anisotropic etching characteristics of the single-crystal silicon wafer in the etching solution.

[0101] The anisotropic etching characteristic of single-crystal silicon wafers in etching solutions refers to the different etching rates of different crystal faces of single-crystal silicon wafers in etching solutions. The reason for this is that there are differences in the atomic arrangement density of different crystal faces in the crystal structure of single-crystal silicon wafers. For example, in alkaline solutions (such as KOH, TMAH), the atoms of low-index crystal faces (such as the (111) face) are tightly arranged, and the etching rate is extremely low; while the atoms of high-index crystal faces (such as the (100) face) are loosely arranged, and the etching rate is high.

[0102] Single-crystal silicon wafers with a (100) crystal orientation exhibit extremely strong anisotropic etching characteristics in KOH or TMAH solutions. The etching rate of the (100) plane is more than 100 times that of the (111) plane. This difference causes the etching process to proceed rapidly along the (100) crystal orientation, while it almost stops in the (111) plane direction. This allows for the formation of V-grooves or pyramidal structures with steep sidewalls, such as... Figure 4 As shown.

[0103] Therefore, when the crystal orientation of the single-crystal silicon wafer is (100), the first depth can be determined based on the length of the second hole structure on the second surface. This first depth is the product of half the side length of the window region and the first angle tangent, as shown in equation (1). The side length of the window region corresponds to the length of the second hole structure on the second surface.

[0104] After determining the thickness of the silicon substrate, the silicon substrate can be obtained by thinning a single-crystal silicon wafer with a crystal orientation of (100) to that thickness. After obtaining the silicon substrate, a hard mask layer can be deposited on the silicon substrate to obtain the deposited silicon substrate. The first side and the opposite second side of the deposited silicon substrate both have a hard mask layer.

[0105] For example, the hard mask layer can be a layer of SiO2 with a thickness ranging from 100nm to 500nm grown by thermal oxidation, or a layer of Si3N4 with a thickness ranging from 100nm to 200nm generated by low-pressure chemical vapor deposition.

[0106] The first hard mask layer can block subsequent corrosion and ion etching by KOH or TMAH solution; the second hard mask layer can block subsequent corrosion by KOH or TMAH solution.

[0107] S902, A window region is photolithographically etched on the hard mask layer on the second surface of the deposited silicon substrate.

[0108] The side length of the window area corresponds to the length of the second hole structure on the second surface.

[0109] The length of the second aperture structure on the second surface can be determined based on the beam spot diameter of the charged particle beam. For example, the length D2 of the second aperture structure on the second surface can range from D0 ≤ D2 ≤ D0 / This is to ensure that the aperture has sufficient mechanical strength.

[0110] In one possible implementation, before photolithographically etching the window area, a back alignment mark can also be photolithographically etched on the first side, which is used to identify the photolithographic position on the second side of the silicon substrate.

[0111] Based on this back alignment mark, a window area can be photolithographically etched on the hard mask layer on the second surface of the deposited silicon substrate to facilitate subsequent etching of the second hole structure.

[0112] S903. Use KOH or TMAH solution to etch the second surface of the silicon substrate corresponding to the window area until the depth of the second hole structure formed by etching reaches the first depth, then stop etching.

[0113] During the etching of the second hole structure, the hard mask layer outside the window area can block the corrosion of KOH or TMAH solution.

[0114] In this embodiment of the application, based on the anisotropic etching characteristics of the single-crystal silicon wafer with the (100) crystal orientation, the second surface of the silicon substrate corresponding to the window region is etched using KOH or TMAH solution. When the depth of the second hole structure formed by etching reaches the first depth, the etching will stop automatically. This etching method can effectively reduce the process difficulty and improve the preparation efficiency of the aperture.

[0115] S904. An opening region is photolithographically formed on the hard mask layer on the first surface of the deposited silicon substrate.

[0116] The center of the opening region and the center of the window region are aligned on a straight line. Photolithography creates the opening region, facilitating subsequent etching of the first hole structure on the first surface of the silicon substrate corresponding to the opening region.

[0117] S905. Use deep reactive ion etching technology to etch the first surface of the silicon substrate corresponding to the opening region until the depth of the first hole structure formed by etching reaches the third depth, then stop etching.

[0118] The first hole structure is connected to the second hole structure.

[0119] During the etching of the first hole structure, the hard mask layer outside the opening area can block the corrosion of KOH or TMAH solution and block ion etching.

[0120] In this embodiment of the application, the third depth is determined based on the second depth, the length of the opening region, and the first angle, wherein the third depth is the sum of half the length of the opening region and the tangent of the first angle, plus the second depth.

[0121] like Figure 10 As shown in the figure, this is a schematic diagram of determining a third depth according to an embodiment of this application. To ensure a smooth transition between the first hole structure and the second hole structure, the third depth can be determined based on the second depth of the first hole structure and the length of the opening region in this embodiment. The third depth can be expressed by equation (4) as follows:

[0122] (4)

[0123] Where T3 represents the third depth; D1 represents the length of the opening region, which is the same as the diameter of the first hole structure on the first surface of the silicon substrate.

[0124] S906. Remove the hard mask layer on the first surface of the silicon substrate after deep reactive ion etching, and deposit a metal film on the first surface of the silicon substrate to obtain an aperture.

[0125] For example, the metal film layer includes an adhesive layer and a surface conductive layer, and the cross-sectional dimensions of the third pore structure of the metal film layer are the same as the cross-sectional dimensions of the first pore structure.

[0126] The adhesive layer can be made of titanium (Ti) or chromium (Cr), with a thickness ranging from 20nm to 100nm; the surface conductive layer can be made of gold (Au), platinum (Pt), or molybdenum (Mo), with a thickness ranging from 100nm to 300nm.

[0127] In one possible implementation, after removing the hard mask layer on the first surface of the silicon substrate after deep reactive ion etching and setting a metal film on the first surface of the silicon substrate, the silicon substrate after setting the metal film can be diced according to the preset shape size of the aperture to obtain the aperture of the preset shape size.

[0128] In summary, in this embodiment, a single-crystal silicon wafer is used as the substrate, avoiding the problem of easy deformation due to heat during processing and use of metal materials. Based on this, the length of the second aperture structure on the second surface is determined based on the beam spot diameter of the charged particle beam. Furthermore, a method is employed where the second aperture structure is etched first on the second surface of the deposited silicon substrate, followed by the etching of the first aperture structure on the first surface, thereby improving the dimensional accuracy and consistency of the submicron-level aperture.

[0129] like Figure 11 As shown, this figure is a flowchart of another method for preparing an aperture according to an embodiment of this application, including steps S111-S117. Unlike the above embodiments, in this embodiment, an aperture may include multiple aperture holes to reduce the frequency of aperture replacement and extend the normal operating time of the charged particle beam device.

[0130] S111. A hard mask layer is deposited on the silicon substrate to obtain the deposited silicon substrate.

[0131] As is understandable, S111 is the same as S901 mentioned above, and will not be repeated here.

[0132] S112. Based on the beam spot diameter of the charged particle beam and the aperture characteristic information, determine the aperture spacing and layout of multiple first aperture structures.

[0133] The aperture characteristic information may include, but is not limited to, the electronic device structure in which the aperture is applied, the application scenario of the aperture, the aperture size, the mechanical strength of the aperture, and the energy of the electron beam corresponding to the aperture.

[0134] For example, the layout of the first aperture structure on the aperture plate includes, but is not limited to, a single-row, multi-row, or ring-shaped layout, such as... Figures 5-7 As shown, when the aperture spacing is greater than or equal to D0, damage to the adjacent first aperture structure by the charged particle beam can be effectively avoided, while maximizing the utilization of the effective area on the aperture, thereby reducing the frequency of aperture replacement and extending the normal operating time of the charged particle beam equipment.

[0135] S113. Based on the hole spacing and layout of the plurality of first hole structures, a window region is photolithographically formed on the hard mask layer on the second surface of the deposited silicon substrate.

[0136] S114. Use KOH or TMAH solution to etch the second surface of the silicon substrate corresponding to the window area until the depth of the second hole structure formed by etching reaches the first depth, then stop etching.

[0137] S115. An opening region is photolithographically formed on the hard mask layer on the first surface of the deposited silicon substrate.

[0138] The center of the opening area and the center of the window area are on a straight line.

[0139] S116. Use deep reactive ion etching technology to etch the first surface of the silicon substrate corresponding to the opening region until the depth of the first hole structure formed by etching reaches the third depth, then stop etching.

[0140] S117. Remove the hard mask layer on the first surface of the silicon substrate after deep reactive ion etching, and deposit a metal film on the first surface of the silicon substrate to obtain an aperture.

[0141] For example, after removing the hard mask layer on the first surface of the silicon substrate after deep reactive ion etching and depositing a metal film on the first surface of the silicon substrate, it can be done according to... Figures 5-7 The aperture shape shown is obtained by dicing the silicon substrate after the metal film is applied.

[0142] In summary, in this embodiment, a single-crystal silicon wafer is used as the substrate, avoiding the problem of easy deformation due to heat during processing and use of metal materials. Based on this, the length of the second aperture structure on the second surface is determined based on the beam spot diameter of the charged particle beam. Furthermore, a method is employed where the second aperture structure is etched first on the second surface of the deposited silicon substrate, followed by the etching of the first aperture structure on the first surface, thereby improving the dimensional accuracy and consistency of the submicron-level aperture.

[0143] Meanwhile, based on the beam spot diameter of the charged particle beam and the aperture characteristic information, the aperture spacing and layout of multiple first aperture structures can be determined. This allows for the determination of the aperture spacing and layout of multiple apertures on the aperture plate, ensuring that adjacent apertures are not damaged by the charged particle beam, while maximizing the utilization of the effective area on the aperture plate, improving the dimensional accuracy and consistency of submicron-level apertures, and extending the service life of the aperture plate.

[0144] In addition, determining the etching depth and window length based on the beam spot diameter of the charged particle beam ensures the mechanical strength of the aperture, achieves etching process compatibility and high-precision alignment, and avoids cross-contamination. For ease of understanding, the following section will combine... Figure 12 This application provides an overall overview of the aperture fabrication method provided in its embodiments. Figure 12 This is a schematic diagram of an aperture fabrication method provided in an embodiment of this application.

[0145] Step 121: Thin the (100) crystal orientation single crystal silicon wafer to T0 to obtain a silicon substrate.

[0146] Wherein, T0 is determined based on the energy of the charged particle beam and the first coefficient, after determining the second depth of the first hole structure, and then based on the sum of the second depth and the first depth.

[0147] Step 122: Deposit a hard mask layer on the silicon substrate to obtain the deposited silicon substrate.

[0148] For example, SiO2 with a thickness range of 100nm-500nm can be grown as a hard mask layer by thermal oxidation, or Si3N4 with a thickness range of 100nm-200nm can be deposited as a hard mask layer by low-pressure chemical vapor deposition.

[0149] It is understood that in the embodiments of this application, different hard mask layers or the same hard mask layer may be generated on the first side and the opposite second side of the silicon substrate. For example, the first side may use SiO2 as the hard mask layer and the second side may use Si3N4 as the hard mask layer; or the first side may use Si3N4 as the hard mask layer and the second side may use SiO2 as the hard mask layer; or both the first and second sides may use SiO2 as the hard mask layer; or both the first and second sides may use Si3N4 as the hard mask layer.

[0150] Step 123: Photolithography and etching of back alignment marks on the first side of the deposited silicon substrate.

[0151] The back alignment mark 1201 is used to identify the photolithographic position on the second side of the silicon substrate.

[0152] For example, in this embodiment of the application, a portion of the hard mask layer can be removed from the first side of the deposited silicon substrate, and the area where the hard mask layer has been removed can be identified as the back alignment mark.

[0153] Step 124: Flip the deposited silicon substrate and, according to the photolithography pattern of the second side, photolithographically etch a window area on the hard mask layer of the second side of the deposited silicon substrate.

[0154] For example, the photolithographic pattern of the second side can be as follows: Figures 5-7 As shown. In this embodiment, a portion of the hard mask layer can be removed from the second surface of the deposited silicon substrate. The area where the hard mask layer is removed is the window region 1202. The side length of the window region corresponds to the length of the second hole structure on the second surface.

[0155] Step 125: Use KOH or TMAH solution to etch the second surface of the silicon substrate corresponding to the window area until the depth of the second hole structure formed by etching reaches the first depth, then stop etching.

[0156] In this embodiment of the application, based on the anisotropic etching characteristics of the (100) crystal orientation of the single crystal silicon wafer, the etching will stop automatically when the etching depth reaches the first depth. This etching method can effectively reduce the process difficulty and improve the preparation efficiency of the aperture.

[0157] Step 126: According to the photolithography pattern of the first side, photolithography is performed on the hard mask layer of the first side of the deposited silicon substrate to form the opening region.

[0158] For example, in this embodiment of the application, a portion of the hard mask layer can be removed from the first surface of the deposited silicon substrate, and the area where the hard mask layer is removed is the opening region 1203.

[0159] Step 127: Use deep reactive ion etching technology to etch the first surface of the silicon substrate corresponding to the opening region until the depth of the first hole structure formed by etching reaches the third depth, then stop etching.

[0160] In this embodiment, the first surface of the silicon substrate can be etched based on the deep reactive ion etching (DRIE) technique. Since the first hole structure can smoothly transition with the second hole structure when the depth of the first hole structure reaches the third depth.

[0161] Step 128: Remove the hard mask layer on the first surface of the silicon substrate after deep reactive ion etching, and deposit a metal film on the first surface of the silicon substrate to obtain an aperture.

[0162] The metal layer may include an adhesive layer and a surface conductive layer.

[0163] The adhesive layer can be made of Ti or Cr, with a thickness ranging from 20 nm to 100 nm; the surface conductive layer can be made of Au, Pt or Mo, with a thickness ranging from 100 nm to 300 nm.

[0164] For example, by removing the hard mask layer on the first surface of the silicon substrate after deep reactive ion etching and setting a metal film on the first surface of the silicon substrate, a silicon substrate with the metal film can be obtained. Based on this, the silicon substrate with the metal film can be diced according to the preset shape size of the aperture to obtain the aperture.

[0165] Based on the method provided in the embodiments of this application, using a (100) crystal orientation single crystal silicon wafer as a substrate, and utilizing microelectromechanical systems (MEMS) processes such as thinning, photolithography, dry / wet etching, coating, and dicing, multiple apertures can be fabricated on the silicon wafer. A single aperture can contain as many aperture holes as possible, and the aperture hole size accuracy and consistency can reach the nanometer level.

[0166] In summary, in this embodiment, the length of the second hole structure on the second surface is determined based on the beam spot diameter, and the thickness of the silicon substrate is determined based on the anisotropic etching characteristics of the single-crystal silicon wafer in the etching solution and the energy of the charged particle beam, thus avoiding the problem of easy deformation due to heat during the processing and use of metal materials.

[0167] Building upon this, by etching a larger aperture area from the second surface of the deposited silicon substrate, and then etching submicron-sized apertures from the first surface of the deposited silicon substrate, the dimensional accuracy and consistency of the submicron-sized apertures are improved. Furthermore, compared to the method of first creating small apertures and then larger apertures, the method provided in this application embodiment better maintains the mechanical strength of the substrate and the compatibility of the etching process, avoids cross-contamination, and improves alignment accuracy.

[0168] Meanwhile, the method of etching the second side of the silicon substrate based on the anisotropic etching characteristics of single-crystal silicon wafers in etching solution can achieve precise automatic stopping, and does not require the silicon oxide layer of silicon-on-insulator (SOI) wafers as an etching barrier layer, reducing processing steps and lowering processing difficulty and cost.

[0169] Based on the beam spot diameter of the charged particle beam and the characteristics of the aperture, the spacing and layout of multiple aperture holes on the aperture can be determined, ensuring that adjacent aperture holes are not damaged by the charged particle beam, while maximizing the utilization of the effective area on the aperture plate. This improves the dimensional accuracy and consistency of the submicron aperture holes and extends the service life of the aperture plate.

[0170] This application provides a system for fabricating an aperture, see [link to documentation]. Figure 13 The figure is a schematic diagram of the structure of an aperture preparation system provided in an embodiment of this application. Its specific implementation method is consistent with the implementation method and the technical effect achieved in the embodiments of the above method, and some contents will not be repeated.

[0171] This application provides an aperture fabrication system 1300, comprising:

[0172] The deposition module 1301, the first photolithography module 1302, the first etching module 1303, the second photolithography module 1304, the second etching module 1305, and the removal module 1306;

[0173] The deposition module 1301 is used to deposit a hard mask layer on a silicon substrate to obtain a deposited silicon substrate.

[0174] The first photolithography module 1302 is used to photolithographically create a window region on the hard mask layer on the second surface of the deposited silicon substrate;

[0175] The first etching module 1303 is used to etch the second surface of the silicon substrate corresponding to the window area using KOH or TMAH solution until the depth of the second hole structure formed by etching reaches the first depth, and then the etching stops.

[0176] The second photolithography module 1304 is used to photolithographically create an opening region on the hard mask layer of the first surface of the deposited silicon substrate, wherein the center of the opening region and the center of the window region are on a straight line.

[0177] The second etching module 1305 is used to etch the first surface of the silicon substrate corresponding to the opening region using deep reactive ion etching technology until the depth of the first hole structure formed by etching reaches the third depth, and then stop etching, wherein the first hole structure is connected to the second hole structure.

[0178] The removal module 1306 is used to remove the hard mask layer on the first surface of the silicon substrate after deep reactive ion etching, and to set a metal film on the first surface of the silicon substrate to obtain an aperture.

[0179] In one possible implementation, the system further includes: a first determining module;

[0180] The first determining module is used to determine the length of the second aperture structure on the second surface based on the beam spot diameter of the charged particle beam, wherein the length of the second aperture structure on the second surface corresponds to the side length of the window region; wherein the length of the second aperture structure on the second surface is greater than or equal to The beam spot diameter is times that of the beam spot diameter, and is less than or equal to the beam spot diameter.

[0181] In one possible implementation, the system further includes: a second determining module;

[0182] The second determining module is used to determine a first depth based on the length of the second hole structure on the second surface, wherein the first depth is the product of half the side length of the window region and the first angle tangent.

[0183] In one possible implementation, the system further includes: a third determining module;

[0184] The third determining module is used to determine the second depth of the first hole structure based on the energy of the charged particle beam and the first coefficient; and to determine the thickness of the silicon substrate based on the sum of the second depth and the first depth.

[0185] In one possible implementation, the system further includes: a fourth determining module;

[0186] The fourth determining module is used to determine the third depth based on the second depth, the length of the opening region, and the first angle, wherein the third depth is the sum of half the length of the opening region and the tangent of the first angle, plus the second depth.

[0187] In one possible implementation, the system further includes: a fifth determining module;

[0188] The fifth determining module is used to determine the aperture spacing and layout of multiple first aperture structures based on the beam spot diameter of the charged particle beam and the aperture characteristic information.

[0189] The first photolithography module is specifically used to: photolithographically print multiple window regions on the hard mask layer on the second surface of the deposited silicon substrate based on the hole spacing and layout of the multiple first hole structures.

[0190] In summary, the system provided in this application determines the length of the second hole structure on the second surface based on the beam spot diameter, and determines the thickness of the silicon substrate based on the anisotropic etching characteristics of the single-crystal silicon wafer in the etching solution and the energy of the charged particle beam, thus avoiding the problem of easy deformation due to heat during the processing and use of metal materials.

[0191] Building upon this, by etching a larger aperture area from the second surface of the deposited silicon substrate, and then etching submicron-sized apertures from the first surface of the deposited silicon substrate, the dimensional accuracy and consistency of the submicron-sized apertures are improved. Furthermore, compared to the method of first creating small apertures and then larger apertures, the method provided in this application embodiment better maintains the mechanical strength of the substrate and the compatibility of the etching process, avoids cross-contamination, and improves alignment accuracy.

[0192] Meanwhile, the method of etching the second side of the silicon substrate based on the anisotropic etching characteristics of single-crystal silicon wafers in etching solution can achieve precise automatic stopping, and does not require the silicon oxide layer of silicon-on-insulator (SOI) wafers as an etching barrier layer, reducing processing steps and lowering processing difficulty and cost.

[0193] Based on the beam spot diameter of the charged particle beam and the characteristics of the aperture, the spacing and layout of multiple aperture holes on the aperture can be determined, ensuring that adjacent aperture holes are not damaged by the charged particle beam, while maximizing the utilization of the effective area on the aperture plate. This improves the dimensional accuracy and consistency of the submicron aperture holes and extends the service life of the aperture plate.

[0194] This application also provides a scanning electron microscope, including an aperture as described above.

[0195] It should be noted that the various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0196] The above description is merely one specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A light barrier, characterized in that The metal film layer, the silicon substrate, the hard mask layer and the aperture hole are sequentially arranged. The silicon substrate has a first surface and an opposite second surface, the first surface has a first hole structure, and the second surface has a second hole structure, a length of the second hole structure on the second surface is determined by a beam spot diameter of the charged particle beam; The metal film layer has a third hole structure, and the hard mask layer has a fourth hole structure; The aperture hole is formed by the third hole structure, the first hole structure, the second hole structure and the fourth hole structure. The length of the second hole structure on the second surface is determined by the beam spot diameter of the charged particle beam, comprising:

2. The light barrier of claim 1, wherein, The thickness of the silicon substrate is determined based on the length of the second hole structure on the second surface and the energy of the charged particle beam. The length of the second hole structure on the second face is greater than or equal to a beam spot diameter, and less than or equal to the beam spot diameter.

3. The light barrier of claim 1, wherein, The thickness of the silicon substrate is determined based on the length of the second hole structure on the second surface and the energy of the charged particle beam, comprising:

4. The light barrier of claim 3, wherein, Based on the length of the second hole structure on the second surface, a first depth of the second hole structure is determined; Based on the first depth and the energy of the charged particle beam, the thickness of the silicon substrate is determined. The determination of the thickness of the silicon substrate based on the first depth and the energy of the charged particle beam comprises:

5. The light barrier of claim 4, wherein, Based on the energy of the charged particle beam and a first coefficient, a second depth of the first hole structure is determined; The sum of the first depth and the second depth is determined as the thickness of the silicon substrate. The second hole structure is a pyramid-shaped three-dimensional structure obtained by anisotropic wet etching of the second surface of the silicon substrate.

6. The light barrier according to any one of claims 1 to 5, characterized in that Comprising:

7. A method of making an optical aperture, characterized by, Depositing a hard mask layer on the silicon substrate to obtain a deposited silicon substrate; Photoetching a window region on the hard mask layer on the second surface of the deposited silicon substrate; Etching the second surface of the silicon substrate corresponding to the window region with KOH or TMAH solution until the depth of the second hole structure formed by etching reaches a first depth, and then stopping etching; Photoetching an opening region on the hard mask layer on the first surface of the deposited silicon substrate, the center of the opening region and the center of the window region being on a straight line; Etching the first surface of the silicon substrate corresponding to the opening region by using a deep reactive ion etching technology until the depth of the first hole structure formed by etching reaches a third depth, and then stopping etching, wherein the first hole structure and the second hole structure are in communication; Removing the hard mask layer on the first surface of the silicon substrate after deep reactive ion etching, and arranging a metal film on the first surface of the silicon substrate to obtain an aperture. Before etching the second surface of the silicon substrate corresponding to the window region with KOH or TMAH solution, further comprising:

8. The method of claim 7, wherein, Determining the length of the second hole structure on the second surface based on the beam spot diameter of the charged particle beam, the length of the second hole structure on the second surface corresponding to the side length of the window region; Before the depth of the second hole structure formed by etching reaches the first depth, further comprising: wherein the length of the second aperture structure on the second face is greater than or equal to a beam spot diameter and less than or equal to twice the beam spot diameter.

9. The method of claim 7, wherein, Determining the first depth based on the length of the second hole structure on the second surface, wherein the first depth is the product of one-half of the side length of the window region and the tangent value of the first angle. Before depositing the hard mask layer on the silicon substrate to obtain the deposited silicon substrate, further comprising:

10. The method of claim 7, wherein, ​ determining a second depth of the first aperture structure based on the energy of the charged particle beam and the first coefficient; determining a thickness of the silicon substrate based on a sum of the second depth and the first depth.

11. The method of claim 10, wherein, the etching of the first surface of the silicon substrate corresponding to the opening region by the deep reactive ion etching technology before the depth of the first aperture structure reaches a third depth, comprises: determining the third depth based on the second depth, a length of the opening region and a tangent of the first angle, wherein the third depth is a sum of one half of the product of the length of the opening region and the tangent of the first angle and the second depth.

12. The method according to any one of claims 7-11, characterized in that, before the window region is photoetched on the second surface of the deposited silicon substrate, further comprising: determining an aperture spacing and a layout of the plurality of first aperture structures based on a beam spot diameter of the charged particle beam and the aperture characteristic information; the photoetching of the window region on the second surface of the deposited silicon substrate, comprises: photoetching a plurality of window regions on the second surface of the deposited silicon substrate based on the aperture spacing and the layout of the plurality of first aperture structures.

13. A scanning electron microscope, characterized by an aperture comprising any one of claims 1-6.

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