Photoresist masks and their manufacturing methods, and methods for manufacturing metal structures

Abstract

The application discloses a photoresist mask, a manufacturing method thereof and a manufacturing method of a metal structure. The photoresist mask comprises a first photoresist layer, which is formed on a substrate and has a first opening exposing the substrate; a metal layer, which is formed on the first photoresist layer and has a limited opening with a smaller width than the first opening in a region corresponding to the first opening; and a second photoresist layer, which is formed on the metal layer and has a second opening completely exposing the limited opening, wherein the first photoresist layer and the second photoresist layer are sensitive to different light. The application can ensure that the width of the metal structure is not affected after removing the residual photoresist.

Description

Technical Field

[0001] This invention relates to the field of integrated circuit manufacturing technology, and in particular to a photoresist mask and its manufacturing method, as well as a method for manufacturing metal structures. Background Technology

[0002] The manufacturing of integrated circuits is inseparable from photolithography. In photolithography, photoresist is typically used as a mask. After exposure and development, an opening of a specific shape is obtained, and then metal material is deposited based on the opening to obtain the desired metal structure. To facilitate subsequent mask removal, a double-layer photoresist is usually used, with undercut openings formed on the double-layer photoresist. The opening of the upper photoresist determines the width of the metal structure, and the opening width of the lower photoresist is larger than that of the upper photoresist to prevent the metal structure from adhering to the lower photoresist.

[0003] Due to limitations in the precision of the exposure process, residual photoresist remains within the openings after exposure and development. Existing technologies typically use plasma etching to remove this residual. However, the inventors of this application have discovered through long-term research that plasma etching is a non-directional process. It not only removes residual photoresist but also etches the sidewalls of the openings, increasing the width of the openings between the upper and lower photoresist layers, resulting in a metal structure width greater than expected. Figure 1 The diagram shown is a comparison of the opening width of the mask before and after removing residual adhesive in the prior art. Figure 1 Before removing residual photoresist, 'a' represents the opening width of the upper photoresist layer L1, which is 'd', and the opening width of the lower photoresist layer L2, which is 'D'. Figure 1 After removing the residual photoresist, the opening width of the upper photoresist L1 is d+x, and the opening width of the lower photoresist L2 is D+X. The opening widths are increased by x and X respectively. Since the opening width of the upper photoresist L1 determines the width of the metal structure, the final width of the obtained metal structure will be larger. Summary of the Invention

[0004] The purpose of this invention is to provide a photoresist mask and its manufacturing method, as well as a method for manufacturing a metal structure, to solve the problem that the width of the metal structure increases after removing residual photoresist in the prior art, and to ensure that the width of the metal structure is not affected after removing residual photoresist.

[0005] To solve the above-mentioned technical problems, the present invention provides a photoresist mask, comprising:

[0006] A first photoresist layer is formed on a substrate, the first photoresist layer having a first opening that exposes the substrate;

[0007] A metal layer is formed on the first photoresist layer, and a limiting opening with a width smaller than the first opening is formed in the region of the metal layer corresponding to the first opening;

[0008] A second photoresist layer is formed on the metal layer, the second photoresist layer having a second opening that fully exposes the defined opening, wherein the first photoresist layer and the second photoresist layer are sensitive to different light.

[0009] Preferably, the first opening, the defined opening, and the second opening are symmetrical about the same line of symmetry.

[0010] Preferably, the width of the second opening is greater than the width of the defined opening.

[0011] Preferably, the material of the first photoresist layer is ultraviolet photoresist, and the material of the second photoresist layer is electron beam photoresist.

[0012] To solve the above-mentioned technical problems, the present invention also provides a method for manufacturing a photoresist mask, comprising:

[0013] A first photoresist layer, a metal layer, and a second photoresist layer are sequentially formed on a substrate, wherein the first photoresist layer and the second photoresist layer are sensitive to different light.

[0014] Photolithography is performed on the second photoresist layer to form a second opening that exposes the metal layer;

[0015] The exposed metal layer is etched to form a defined opening that exposes the first photoresist layer;

[0016] Photolithography is performed on the exposed first photoresist layer to form an initial opening that exposes the substrate;

[0017] The first photoresist layer is plasma etched through the initial opening to expand the initial opening into a first opening with a width greater than the defined opening.

[0018] Preferably, the first opening, the defined opening, and the second opening are symmetrical about the same line of symmetry.

[0019] Preferably, the first photoresist layer is sensitive to ultraviolet light, and the second photoresist layer is sensitive to electron beams.

[0020] Preferably, the metal layer is etched using an ICP dry etching process.

[0021] To solve the above-mentioned technical problems, the present invention also provides a method for manufacturing a metal structure, comprising:

[0022] A photoresist mask according to any of the foregoing methods is disposed on a substrate, or a photoresist mask is formed on the substrate according to the manufacturing method of the photoresist mask according to any of the foregoing methods.

[0023] Evaporation deposition is performed through the first opening, the defined opening, and the second opening to form a metal structure on the substrate with a width consistent with the width of the defined opening.

[0024] Preferably, the evaporation coating through the first opening, the defined opening, and the second opening includes:

[0025] The photoresist layer is deposited by tilting evaporation through the defined opening along a first direction that forms a preset angle with the second photoresist layer.

[0026] The photoresist layer is deposited by tilting evaporation through the defined opening along a second direction that is symmetrical to the normal direction of the second photoresist layer in the first direction.

[0027] Unlike existing technologies, the photoresist mask provided by this invention has a metal layer between two photoresist layers. The first photoresist layer has a first opening, the metal layer has a defined opening, and the second photoresist layer has a second opening that fully exposes the defined opening. The defined opening is formed in the metal layer, and the metal layer is not affected by the removal of residual photoresist. Therefore, the width of the defined opening remains constant. Based on the defined opening, the desired width of the metal structure can be obtained, thereby ensuring that the width of the metal structure is not affected after the removal of residual photoresist.

[0028] The photoresist mask manufacturing method and the metal structure manufacturing method provided by this invention belong to the same inventive concept as the photoresist mask and have the same technical effects, so they will not be described in detail here. Attached Figure Description

[0029] Figure 1 This is a schematic diagram comparing the opening width of the mask before and after removing residual adhesive in the prior art.

[0030] Figure 2 This is a schematic diagram of the structure of the photoresist mask provided in the first embodiment of the present invention.

[0031] Figure 3 a to Figure 3 e is a schematic diagram of the manufacturing method of the photoresist mask provided in the second embodiment of the present invention.

[0032] Figure 4 a to Figure 4 c is a schematic diagram of the manufacturing method of the metal structure provided in the third embodiment of the present invention. Detailed Implementation

[0033] The specific embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. The advantages and features of the present invention will become clearer from the following description and claims. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the present invention.

[0034] In the description of this invention, it should be understood that the terms "center", "upper", "lower", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0035] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0036] Please refer to Figure 2 The first embodiment of the present invention provides a photoresist mask. The photoresist mask includes: a first photoresist layer 11 for forming on a substrate 100, the first photoresist layer 11 having a first opening K1 exposing the substrate 100; a metal layer 12 formed on the first photoresist layer 11, the metal layer 12 having a limiting opening K2 with a width smaller than the first opening K1 in the region corresponding to the first opening K1; and a second photoresist layer 13 formed on the metal layer 12, the second photoresist layer 13 having a second opening K3 that completely exposes the limiting opening K2, wherein the first photoresist layer 11 and the second photoresist layer 13 are sensitive to different light.

[0037] The photoresist mask in this embodiment has two photoresist layers, and a metal layer is disposed between the two photoresist layers. The first photoresist layer has a first opening, the metal layer has a defined opening, and the second photoresist layer has a second opening that completely exposes the defined opening. The defined opening is formed in the metal layer, and the metal layer is not affected by the removal of residual photoresist. Therefore, the width of the defined opening remains unchanged. When depositing metal material to form a metal structure, the defined opening is the area through which the deposited material passes. Therefore, the desired width of the metal structure can be obtained based on the defined opening, thereby ensuring that the width of the metal structure is not affected after the removal of residual photoresist.

[0038] In this embodiment, the first opening K1, the limiting opening K2, and the second opening K3 are symmetrical about the same line of symmetry. The vertical distances from the two side walls of the first opening K1 to the two side walls of the limiting opening K2 are equal, and the vertical distances from the two side walls of the limiting opening K2 to the two side walls of the first opening K1 are also equal. Furthermore, the width of the second opening K3 can be greater than the width of the limiting opening K2.

[0039] Because the first photoresist layer 11 and the second photoresist layer 13 are sensitive to different light, the second photoresist layer 13 is not affected when the first photoresist layer 11 is photolithographically processed, and similarly, the first photoresist layer 11 is not affected when the second photoresist layer 13 is photolithographically processed. This facilitates the formation of the first opening K1 and the second opening K3. In this embodiment, the material of the first photoresist layer 11 is ultraviolet photoresist, and the material of the second photoresist layer 13 is electron beam photoresist. The metal layer 12 can be any metal material. For example, the first photoresist layer 11 uses SPR955 photoresist with a thickness of approximately 500 nm, the metal layer 12 uses aluminum with a thickness of approximately 200 nm, and the second photoresist layer 13 uses PMMA A4 495 photoresist with a thickness of approximately 500 nm.

[0040] Reference Figure 3 a to Figure 3 e, and combined Figure 2 The second embodiment of this application provides a method for manufacturing a photoresist mask. The manufacturing method includes the following steps:

[0041] S11: A first photoresist layer, a metal layer, and a second photoresist layer are sequentially formed on a substrate. The first photoresist layer and the second photoresist layer are sensitive to different light. For example, Figure 3 Figure a shows a schematic diagram after the formation of the first photoresist layer, the metal layer, and the second photoresist layer. The first photoresist layer 11, the metal layer 12, and the second photoresist layer 13 are formed on the substrate 100. Specifically, photoresist can be coated onto the substrate 100 by spin coating to form the first photoresist layer 11, then a metal layer 12 can be formed on the first photoresist layer 11 by thermal evaporation deposition, and finally, photoresist can be coated onto the metal layer 12 by spin coating to form the second photoresist layer 13.

[0042] S12: Photolithography is performed on the second photoresist layer to form a second opening exposing the metal layer. This can be achieved by exposing the second photoresist layer with a photolithography plate and then developing it to form the second opening. For example... Figure 3 Figure b shows a schematic diagram after the second opening is formed. After exposure and development, the unexposed portion of the second photoresist layer 13 is retained, while the exposed portion dissolves in the developer, thereby forming the second opening K3. In this embodiment, the second photoresist layer 13 is sensitive to electron beams and can only be exposed by electron beams.

[0043] S13: Etch the exposed metal layer to form a defined opening that exposes the first photoresist layer. For example... Figure 3 Figure c shows a schematic diagram after the defined opening is formed. The metal layer 12 within the second opening K3 is etched away to form the defined opening K2. The metal layer 12 can be etched using various etching processes. For example, when the metal layer 12 is made of aluminum, it can be etched using an ICP (inductively coupled plasma) dry etching process. Since the width of the defined opening K2 will not exceed the width of the second opening K3, the width of the defined opening K2 is determined by the second opening K3. The precision of the second opening K3 is determined by the precision of the exposure process. The higher the precision of the exposure process, the closer the width of the defined opening K2 is to the desired value. Therefore, in this invention, the second photoresist layer 13 is exposed using a high-precision electron beam exposure process.

[0044] S14: Photolithography is performed on the exposed first photoresist layer to form the initial opening of the exposed substrate. For example... Figure 3 Figure d shows a schematic diagram after the initial opening is formed. Since the first photoresist layer 11 and the second photoresist layer 13 are sensitive to different light, and only the opening K3 exposes the first photoresist layer 11, exposure of the first photoresist layer 11 within the opening K3 will not affect the second photoresist layer 13. After exposure and development, the unexposed portion of the first photoresist layer 11 is retained, while the exposed portion dissolves in the developer, thus forming the initial opening K4. In this embodiment, the first photoresist layer 11 is sensitive to ultraviolet light and can only be exposed to ultraviolet light.

[0045] S15: Plasma etching is performed on the first photoresist layer through the initial opening to expand the initial opening into a first opening with a width greater than the defined opening. For example... Figure 3 Figure e shows a schematic diagram after the formation of the first opening. Plasma etching is a non-directional etching process that can etch away photoresist with almost no etching of materials such as metals and substrates. Since the first photoresist layer 11 is exposed on both sides of the initial opening K4, it is etched laterally, thus widening the initial opening K4 and eventually expanding into a first opening K1 with a width greater than that of the limiting opening K2. Simultaneously, plasma etching also removes residual photoresist from the first opening K1, the limiting opening K2, and the second opening K3. The first opening K1 and the limiting opening K2 together form an undercut. Similarly, the width of the second opening K3 also increases, and the second photoresist layer 13 becomes thinner, but the width of the limiting opening K2 remains constant, so the change in the width of the second opening K3 has no impact.

[0046] In this embodiment, the first opening K1, the limiting opening K2, and the second opening K3 are symmetrical about the same line of symmetry. The vertical distances from the two side walls of the first opening K1 to the two side walls of the limiting opening K2 are equal, and the vertical distances from the two side walls of the limiting opening K2 to the two side walls of the first opening K1 are also equal. Furthermore, the width of the second opening K3 can be greater than the width of the limiting opening K2.

[0047] Reference Figure 4 a to Figure 4 c, and combined Figure 2 and Figure 3 The third embodiment of this application provides a method for manufacturing a metal structure. The manufacturing method includes the following steps:

[0048] S21: The photoresist mask of the aforementioned embodiment is disposed on a substrate, or a photoresist mask is formed on a substrate according to the manufacturing method of the photoresist mask of the aforementioned embodiment. Wherein, Figure 2 Taking the photoresist mask shown or the photoresist mask formed according to the aforementioned second embodiment as an example, such as... Figure 4 Figure a shows a schematic diagram after the photoresist mask is formed on the substrate 100.

[0049] S22: Evaporation deposition is performed through a first opening, a defining opening, and a second opening to form a metal structure on the substrate with a width consistent with the width of the defining opening. Wherein, for example... Figure 4 Figure b shows a schematic diagram after the metal structure is formed. The first opening K1, the limiting opening K2, and the second opening K3 expose the substrate 100, and the limiting opening K2 has the smallest width. During the evaporation deposition, the evaporated material can only be deposited on the substrate 100 through the limiting opening K2, so the metal structure 200 is finally formed. The width of the metal structure 200 is the same as the width of the limiting opening K2.

[0050] In this embodiment, after the metal structure 200 is formed, the first photoresist layer 11 can be removed by a peeling process. The metal layer 12 and the second photoresist layer 13 will then be removed along with the first photoresist layer 11. Since the first opening K1 and the limiting opening K2 constitute an undercut opening, the metal structure 200 will not adhere to the first photoresist layer 11, thus allowing the first photoresist layer 11 to be directly peeled off without damaging the metal structure 200.

[0051] In some embodiments of this application, the metal structure can be formed using various evaporation deposition processes, such as direct evaporation or oblique evaporation. Taking oblique evaporation as an example, evaporation deposition is performed through a first opening, a defined opening, and a second opening; that is, step S22 specifically includes:

[0052] S221: Tilt evaporation deposition is performed by defining an opening along a first direction at a preset angle to the second photoresist layer. For example... Figure 4As shown in b, the first direction A and the second photoresist layer 13 form a preset angle. This preset angle can be adjusted according to actual needs. The evaporated material will move along the first direction A and eventually be deposited on the substrate 100.

[0053] S222: An inclined evaporation deposition is performed by defining an opening along a second direction symmetrical to the normal direction of the second photoresist layer as the first direction. For example... Figure 4 As shown in b, the second direction B and the second photoresist layer 13 also form a preset angle, but it is symmetrical to the first direction A in the normal direction of the second photoresist layer 13. The evaporated material will move along the second direction B and eventually be deposited on the substrate 100. The two tilted evaporation coatings can ensure the integrity and flatness of the metal structure 200.

[0054] The method for manufacturing the metal structure in this embodiment can be applied to superconducting quantum chips. For example, this method can be used to manufacture Josephson junctions, the key structure of which is a superconducting wire.

[0055] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," or "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0056] The above are merely preferred embodiments of the present invention and do not constitute any limitation on the present invention. Any equivalent substitutions or modifications made by those skilled in the art to the technical solutions and content disclosed in the present invention without departing from the scope of the present invention shall be deemed to have remained within the protection scope of the present invention.

Claims

1. A method of manufacturing a photoresist mask, characterized by, The application relates to a method for manufacturing a metal structure on a substrate, comprising the following steps: forming a first photoresist layer, a metal layer and a second photoresist layer on the substrate in sequence, wherein the first photoresist layer and the second photoresist layer are sensitive to different light rays; performing photoetching on the second photoresist layer to form a second opening exposing the metal layer; performing etching on the exposed metal layer to form a defined opening exposing the first photoresist layer and having a width equal to that of the second opening; performing photoetching on the exposed first photoresist layer to form an initial opening exposing the substrate and having a width equal to that of the defined opening; performing plasma etching on the first photoresist layer through the initial opening to keep the width of the defined opening unchanged, expand the initial opening into a first opening with a width greater than that of the defined opening, and expand the width of the second opening.

2. The manufacturing method according to claim 1, characterized by, The first opening, the defined opening and the second opening are left-right symmetrical along the same symmetry line.

3. The production method according to claim 1, characterized by The first photoresist layer is sensitive to ultraviolet light, and the second photoresist layer is sensitive to an electron beam.

4. The production method according to claim 1, characterized by The metal layer is etched by using an ICP dry etching process.

5. A method of manufacturing a metal structure, characterized by, The application further relates to a method for manufacturing a photoresist mask on a substrate, comprising the following steps: forming a photoresist mask according to the method for manufacturing a photoresist mask according to any one of claims 1 to 4 on the substrate; performing evaporation plating through the first opening, the defined opening and the second opening to form a metal structure with a width consistent with that of the defined opening on the substrate.

6. The production method according to claim 5, wherein The method for performing evaporation plating through the first opening, the defined opening and the second opening comprises the following steps: performing inclined evaporation plating through the defined opening along a first direction at a preset angle with the second photoresist layer; performing inclined evaporation plating through the defined opening along a second direction symmetrical to the first direction in the normal direction of the second photoresist layer.

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