Photoetching method based on full-transparent substrate

Abstract

The invention provides a photoetching method based on a full-transparent substrate, and relates to the technical field of semiconductors. When the method is executed, firstly, an aluminum layer is deposited on the surface of a full-transparent substrate, then, photoresist is uniformly distributed on the surface of the aluminum layer, then, the position of the surface of the full-transparent substrate is determined according to the aluminum layer, then, the photoresist is exposed according to the position of the surface of the full-transparent substrate, and finally, the exposed photoresist is developed. Therefore, by depositing the aluminum layer on the surface of the full-transparent substrate, the light intensity of the reflected signal can be enhanced when the surface of the full-transparent substrate is subjected to a photoetching process, so that a sensor for receiving light rays can smoothly and accurately distinguish the reflected signal and accurately determine the position of the surface of the full-transparent substrate; and thus, automatic photoetching based on the full-transparent substrate is realized.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a photolithography method based on a fully transparent substrate. Background Art

[0002] One of the key technologies that enables an automatic lithography machine to perform automatic lithography is the ability to automatically find the substrate surface that needs to be exposed. This technology uses the ability of the substrate to reflect the light emitted by the halogen lamp. By detecting the reflected light, the precise position of the substrate surface is determined to control the exposure focal plane of the pattern for exposure.

[0003] However, for fully transparent substrates, such as semi-insulating SiC substrates, quartz substrates, etc., since the light reflected back from the substrate surface is extremely weak, the sensor that receives the light cannot effectively identify the useful light signal, which will cause errors in the action of searching for the substrate surface, which may lead to subsequent exposure failure and blurred graphics, and thus make automatic lithography impossible.

[0004] In summary, how to realize automatic lithography based on a fully transparent substrate is a problem that those skilled in the art need to solve urgently. Summary of the invention

[0005] In view of this, the present application provides a lithography method based on a fully transparent substrate, aiming to realize automatic lithography based on a fully transparent substrate.

[0006] The present application provides a method based on a fully transparent substrate, comprising:

[0007] Depositing an aluminum layer on the surface of the fully transparent substrate;

[0008] Applying photoresist on the surface of the aluminum layer;

[0009] Determining the position of the surface of the fully transparent substrate according to the aluminum layer;

[0010] Exposing the photoresist according to the position of the surface of the fully transparent substrate;

[0011] The exposed photoresist is developed.

[0012] Optionally, developing the exposed photoresist includes:

[0013] The exposed photoresist is developed with a developer so that the developed photoresist forms the same pattern as the aluminum layer corroded by the developer.

[0014] Optionally, after developing the exposed photoresist so that the developed photoresist forms the same pattern as the aluminum layer corroded by the developer, the method further comprises:

[0015] Depositing metal on the surface of the developed photoresist and the surface of the aluminum layer corroded by the developer;

[0016] Stripping the deposited metal to obtain a metal having the same shape as the pattern formed by the aluminum layer corroded by the developer;

[0017] The aluminum layer corroded by the developing solution is removed by using the developing solution.

[0018] Optionally, applying photoresist uniformly on the surface of the aluminum layer includes:

[0019] Applying a stripping photoresist on the surface of the aluminum layer;

[0020] Drying the stripped photoresist;

[0021] Applying the photoresist on the surface of the stripped photoresist after drying;

[0022] The photoresist is dried.

[0023] Optionally, exposing the photoresist according to the position of the surface of the fully transparent substrate includes:

[0024] The stripping photoresist and the photoresist are exposed according to the position of the surface of the fully transparent substrate.

[0025] Optionally, developing the exposed photoresist includes:

[0026] The exposed stripped photoresist and the exposed photoresist are developed so that the developed stripped photoresist and the aluminum layer form the same pattern.

[0027] Optionally, the method further includes:

[0028] Depositing metal on the surface of the developed photoresist, the surface of the developed stripped photoresist, and the surface of the aluminum layer corroded by the developer;

[0029] Stripping the deposited metal to obtain a metal having the same shape as the pattern formed by the aluminum layer corroded by the developer;

[0030] The aluminum layer corroded by the developing solution is removed by using the developing solution.

[0031] Optionally, removing the aluminum layer corroded by the developer by using the developer includes:

[0032] Immersing the fully transparent substrate, the aluminum layer corroded by the developer, and the metal having the same pattern shape as that formed by the aluminum layer corroded by the developer in the developer until the aluminum layer corroded by the developer is completely removed;

[0033] The fully transparent substrate and the metal having the same pattern shape as that formed by the aluminum layer corroded by the developer are rinsed with water and dried.

[0034] Optionally, the thickness of the aluminum layer is 100 nm; and the thickness of the photoresist is greater than 1 um.

[0035] The present application provides a photolithography method based on a fully transparent substrate. When executing the method, an aluminum layer is first deposited on the surface of the fully transparent substrate, then a photoresist is uniformly applied on the surface of the aluminum layer, then the position of the surface of the fully transparent substrate is determined according to the aluminum layer, and then the photoresist is exposed according to the position of the surface of the fully transparent substrate, and finally the exposed photoresist is developed. In this way, by depositing an aluminum layer on the surface of the fully transparent substrate, the light intensity of the reflected signal can be enhanced when the photolithography process is performed on the surface of the fully transparent substrate, so that the sensor receiving the light can smoothly and accurately identify the reflected signal and accurately determine the position of the surface of the fully transparent substrate, thereby realizing automatic photolithography based on the fully transparent substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in this embodiment or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0037] Figure 1 A schematic diagram of determining a focal plane based on a non-fully transparent substrate;

[0038] Figure 2 A schematic diagram of determining the focal plane based on a fully transparent substrate;

[0039] Figure 3 It is a schematic diagram of exposure based on a non-fully transparent substrate;

[0040] Figure 4 It is a schematic diagram of exposure based on a fully transparent substrate;

[0041] Figure 5 It is a schematic diagram of development based on a non-fully transparent substrate;

[0042] Figure 6 It is a schematic diagram of development based on a fully transparent substrate;

[0043] Figure 7 Schematic diagram of metal deposition based on a non-fully transparent substrate;

[0044] Figure 8 Schematic diagram of metal deposition based on a fully transparent substrate;

[0045] Fig. 9 Schematic diagram of metal lift-off based on non-fully transparent substrate;

[0046] Fig.10 Schematic diagram of metal lift-off based on fully transparent substrate;

[0047] Fig.11 A flow chart of a photolithography method based on a fully transparent substrate provided in an embodiment of the present application;

[0048] Fig.12 A schematic diagram of a substrate preparation provided in an embodiment of the present application;

[0049] Fig.13 A schematic diagram of depositing an aluminum layer on a fully transparent substrate provided in an embodiment of the present application;

[0050] Fig.14 A schematic diagram of uniformly distributing photoresist on the surface of an aluminum layer provided in an embodiment of the present application;

[0051] Fig.15 A schematic diagram of determining a focal plane based on a fully transparent substrate provided in an embodiment of the present application;

[0052] Fig.16 A schematic diagram of a fully transparent substrate exposure method provided in an embodiment of the present application;

[0053] Fig.17 A schematic diagram of a fully transparent substrate development method provided in an embodiment of the present application;

[0054] Fig.18 A schematic diagram of metal deposition based on a fully transparent substrate provided in an embodiment of the present application;

[0055] Fig.19 A schematic diagram of metal peeling based on a fully transparent substrate provided in an embodiment of the present application;

[0056] Fig. 20 A schematic diagram of a fully transparent substrate rinsing method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0057] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. The present application provides a photolithography method based on a fully transparent substrate, which is used in the field of semiconductor technology. The above is only an example and does not limit the application field of the method and device name provided in the present application.

[0058] One of the key technologies that enables an automatic lithography machine to perform automatic lithography is the ability to automatically find the substrate surface that needs to be exposed. This technology uses the ability of the substrate to reflect the light emitted by the halogen lamp. By detecting the reflected light, the precise position of the substrate surface is determined to control the exposure focal plane of the pattern for exposure.

[0059] However, for fully transparent substrates, such as semi-insulating SiC substrates, quartz substrates, etc., since the light reflected back from the substrate surface is extremely weak, the sensor that receives the light cannot effectively identify the useful light signal, which will cause errors in the action of searching for the substrate surface, which may lead to subsequent exposure failure and blurred graphics, and thus make automatic lithography impossible.

[0060] For example, in the focal plane determination stage, Figure 1 As shown, Figure 1 Schematic diagram of determining the focal plane based on a non-transparent substrate. In the focal plane (substrate surface) finding stage, the surface of the non-transparent substrate 8 can reflect a sufficiently strong light signal, so that the light signal detector 6 can accurately capture the light signal emitted by the halogen lamp 5, and then the light signal system can correctly identify the surface position of the non-transparent substrate 8. Figure 2 middle, Figure 2 This is a schematic diagram of determining the focal plane based on a fully transparent substrate. When the halogen lamp 5 is at position a, the light signal reflected from the surface of the fully transparent substrate 2 is extremely weak, and the light signal detector 6 cannot capture the light signal. However, when the halogen lamp 5 is at position b, the light signal detector 6 can capture the light signal, resulting in the light signal system being able to identify the surface position of the wafer stage 1 rather than the surface position of the fully transparent substrate 2.

[0061] During the exposure phase, Figure 3 As shown, Figure 3 This is a schematic diagram based on non-transparent substrate exposure. Since the optical signal system can correctly identify the surface position of the non-transparent substrate 8, the focusing plane of the lithography machine lens 7 is on the surface of the non-transparent substrate 8, so that the photoresist 4 and the stripping photoresist 3 on the surface of the non-transparent substrate 8 can be normally exposed at the focus. It should be noted that the stripping photoresist, namely LOR photoresist, is a photoresist specially used in the metal stripping process. Figure 4 As shown, Figure 4 This is a schematic diagram based on the exposure of a fully transparent substrate. Since the optical signal system identifies the surface of the wafer stage 1 as the surface of the fully transparent substrate 2, the focusing plane of the photolithography machine lens 7 is on the surface of the wafer stage 1, and the photoresist 4 and the stripped photoresist 3 on the surface of the fully transparent substrate 2 are not in focus, and the exposure pattern will be deformed with blurred edges.

[0062] In the development stage, that is, in the stage of forming the pattern, such as Figure 5 As shown, Figure 5Schematic diagram of non-transparent substrate development. Since the photoresist 4 and the stripping photoresist 3 on the surface of the non-transparent substrate 8 can be normally exposed at the focus, the pattern formed after development is the same as the required shape with neat edges. The stripping photoresist 3 is more sensitive to the developer and forms a concave at the bottom after development. Figure 6 As shown, Figure 6 This is a schematic diagram based on development of a fully transparent substrate. Since the photoresist 4 and the stripped photoresist 3 on the surface of the fully transparent substrate 2 are not in focus, the exposed pattern will be deformed with blurred edges. The pattern formed after development is different from the desired shape and has jagged edges.

[0063] During the metal deposition stage, Figure 7 As shown, Figure 7 Schematic diagram of metal deposition based on a non-fully transparent substrate. Since the photoresist 4 at the edge of the photolithography pattern and the stripped photoresist 3 have steep cross sections, the metal 9 inside the pattern and the metal 9 on the photoresist 4 form an obvious fault. Figure 8 As shown, Figure 8 It is a schematic diagram of metal deposition based on a fully transparent substrate. Since the cross-sections of the photoresist 4 at the edge of the photolithography pattern and the stripped photoresist 3 are gentle slopes, the metal 9 inside the pattern and the photoresist 4 and the metal 9 on the stripped photoresist 3 are continuous without obvious faults.

[0064] In the metal stripping stage, such as Fig. 9 As shown, Fig. 9 Schematic diagram of metal stripping based on non-transparent substrate. After metal stripping, the metal 9 inside the pattern remains intact. Fig.10 As shown, Fig.10 This is a schematic diagram of metal stripping based on a fully transparent substrate. After the metal stripping, the metal 9 inside the pattern and the photoresist 4 and the metal 9 on the stripped photoresist 3 are pulled apart by external force. The edge of the pattern is uneven, and there may even be residues of the photoresist 4 and the stripped photoresist 3, which have an adverse effect on subsequent processes.

[0065] After research, the inventor proposed the technical solution of the present application, which is to first deposit an aluminum layer on the surface of a fully transparent substrate, then uniformly apply photoresist on the surface of the aluminum layer, then determine the position of the surface of the fully transparent substrate according to the aluminum layer, then expose the photoresist according to the position of the surface of the fully transparent substrate, and finally develop the exposed photoresist. In this way, by depositing an aluminum layer on the surface of the fully transparent substrate, the light intensity of the reflected signal can be enhanced when the photolithography process is performed on the surface of the fully transparent substrate, so that the sensor receiving the light can smoothly and accurately identify the reflected signal and accurately determine the position of the surface of the fully transparent substrate, thereby realizing automatic photolithography based on the fully transparent substrate.

[0066] In order to enable those skilled in the art to better understand the present application, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application. It should be noted that, for ease of description, only the parts related to the relevant invention are shown in the accompanying drawings. In the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0067] See also Fig.11 , Fig.11 A flow chart of a photolithography method based on a fully transparent substrate provided in an embodiment of the present application includes:

[0068] S101: Depositing an aluminum layer on the surface of a fully transparent substrate Depositing an aluminum layer on the surface of a fully transparent substrate.

[0069] First, if Fig.12 As shown, Fig.12 A schematic diagram of a substrate preparation provided in an embodiment of the present application is provided, wherein a fully transparent substrate 2 is prepared. In the embodiment of the present application, the specific material of the fully transparent substrate 2 is not limited. Fig.13 As shown, Fig.13 A schematic diagram of depositing an aluminum layer on the surface of a fully transparent substrate is provided in an embodiment of the present application. A thin layer of Al metal, ie, an aluminum layer, is deposited on the surface of the fully transparent substrate 2. Optionally, the thickness of the aluminum layer may be 100 nm.

[0070] S102: Evenly apply photoresist on the surface of the aluminum layer.

[0071] The photoresist is evenly applied on the surface of the aluminum layer. The thickness of the photoresist is the thickness required by the normal process. The thickness of the photoresist is usually more than 1um. The thickness of the Al metal can be ignored relative to the photoresist. Fig.14 As shown, Fig.14 A schematic diagram of uniformly applying photoresist on the surface of an aluminum layer is provided in an embodiment of the present application. A stripping photoresist 3 is first coated on the aluminum layer 10, and then the stripping photoresist 3 is dried. After the stripping photoresist 3 is dried, a photoresist 4 is coated on the surface of the stripping photoresist 3, and then the photoresist 4 is dried.

[0072] S103: Determine the position of the fully transparent substrate surface according to the aluminum layer.

[0073] First, in the stage of determining the focal plane (substrate surface), as Fig.15 As shown, Fig.15A schematic diagram of determining the focal plane based on a fully transparent substrate is provided in an embodiment of the present application. The aluminum layer 10 on the surface of the fully transparent substrate 2 can reflect the light signal emitted by the halogen lamp 5 with sufficient intensity, and the light signal detector 6 can accurately capture the light signal emitted by the halogen lamp 5, so that the light signal system can correctly identify the surface position of the fully transparent substrate 2.

[0074] S104: exposing the photoresist according to the position of the surface of the fully transparent substrate.

[0075] During the exposure phase, Fig.16 As shown, Fig.16 A schematic diagram of exposure based on a fully transparent substrate is provided in an embodiment of the present application. Since the aluminum layer 10 on the surface of the fully transparent substrate 2 can reflect the light signal emitted by the halogen lamp 5 with sufficient intensity, the optical signal system can correctly identify the surface position of the fully transparent substrate 2. The focusing plane of the lithography machine lens 7 is on the surface of the fully transparent substrate 2, so that the photoresist 4 and the stripped photoresist 3 on the surface of the fully transparent substrate 2 can be normally exposed at the focus.

[0076] S105: Developing the exposed photoresist.

[0077] During the development stage, the developer will corrode the aluminum layer at the same time, forming a photolithography pattern that is almost the same as the photoresist stripping pattern, without affecting the shape of the photolithography pattern. Fig.17 As shown, Fig.17 A schematic diagram of a fully transparent substrate development is provided for an embodiment of the present application. Since the thickness of the aluminum layer 10 is very thin, such as 100 nm, the alkaline developer can easily corrode the Al metal during the normal development process of the photoresist 4 and the stripped photoresist 3. Therefore, the pattern formed by the photoresist 4, the stripped photoresist 3 and the Al metal is the same as the required shape and has neat edges.

[0078] After executing step S105, the method further includes:

[0079] During the metal deposition stage, Fig.18 As shown, Fig.18 A schematic diagram of metal deposition based on a fully transparent substrate is provided in an embodiment of the present application. After the metal 9 is deposited, since the photoresist profile at the edge of the photolithography pattern is also steep, the gold 9 inside the pattern and the metal 9 on the photoresist 4 also form an obvious fault.

[0080] In the metal stripping stage, such as Fig.19 As shown, Fig.19 A schematic diagram of metal stripping based on a fully transparent substrate is provided in an embodiment of the present application. After the metal stripping, the metal 9 inside the pattern is also left intact, but at this time, the area originally covered with the photoresist 4 and the stripped photoresist 3 is left with the aluminum layer 10.

[0081] Finally, if Fig. 20 As shown, Fig. 20 A schematic diagram of a fully transparent substrate rinsing based on an embodiment of the present application is provided, and the aluminum layer 10 is removed by rinsing with a conventional alkaline developer. Specifically, the fully transparent substrate 2, the aluminum layer 10, and the metal 9 can be immersed in an alkaline developer of normal concentration for a certain period of time, for example, 1 minute to remove the aluminum layer, and finally a rinsing and drying process is performed.

[0082] In the embodiment provided in the present application, an aluminum layer is first deposited on the surface of the fully transparent substrate, then a photoresist is uniformly applied on the surface of the aluminum layer, then the position of the fully transparent substrate surface is determined according to the aluminum layer, and then the photoresist is exposed according to the position of the fully transparent substrate surface, and finally the exposed photoresist is developed. In this way, by depositing an aluminum layer on the surface of the fully transparent substrate, the light intensity of the reflected signal can be enhanced when the photolithography process is performed on the surface of the fully transparent substrate, so that the sensor receiving the light can smoothly and accurately identify the reflected signal and accurately determine the position of the fully transparent substrate surface, thereby realizing automatic photolithography based on the fully transparent substrate.

[0083] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0084] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A photolithography method based on a fully transparent substrate, characterized in that: include: Depositing an aluminum layer on the surface of the fully transparent substrate; Applying photoresist on the surface of the aluminum layer; Determining the position of the surface of the fully transparent substrate according to the aluminum layer; Exposing the photoresist according to the position of the surface of the fully transparent substrate; The exposed photoresist is developed.

2. The method according to claim 1, characterized in that The step of developing the exposed photoresist comprises: The exposed photoresist is developed with a developer so that the developed photoresist forms the same pattern as the aluminum layer corroded by the developer.

3. The method according to claim 2, characterized in that After developing the exposed photoresist so that the developed photoresist forms the same pattern as the aluminum layer corroded by the developer, the method further comprises: Depositing metal on the surface of the developed photoresist and the surface of the aluminum layer corroded by the developer; Stripping the deposited metal to obtain a metal having the same shape as the pattern formed by the aluminum layer corroded by the developer; The aluminum layer corroded by the developing solution is removed by using the developing solution.

4. The method according to claim 1, characterized in that The step of uniformly distributing photoresist on the surface of the aluminum layer comprises: Applying a stripping photoresist on the surface of the aluminum layer; Drying the stripped photoresist; Applying the photoresist on the surface of the stripped photoresist after drying; The photoresist is dried.

5. The method according to claim 4, characterized in that The step of exposing the photoresist according to the position of the surface of the fully transparent substrate comprises: The stripping photoresist and the photoresist are exposed according to the position of the surface of the fully transparent substrate.

6. The method according to claim 5, characterized in that The step of developing the exposed photoresist comprises: The exposed stripped photoresist and the exposed photoresist are developed so that the developed stripped photoresist and the aluminum layer form the same pattern.

7. The method according to claim 6, characterized in that The method further comprises: Depositing metal on the surface of the developed photoresist, the surface of the developed stripped photoresist, and the surface of the aluminum layer corroded by the developer; Stripping the deposited metal to obtain a metal having the same shape as the pattern formed by the aluminum layer corroded by the developer; The aluminum layer corroded by the developing solution is removed by using the developing solution.

8. The method according to claim 3 or 7, characterized in that: The step of removing the aluminum layer corroded by the developer by using the developer comprises: Immersing the fully transparent substrate, the aluminum layer corroded by the developer, and the metal having the same pattern shape as that formed by the aluminum layer corroded by the developer in the developer until the aluminum layer corroded by the developer is completely removed; The fully transparent substrate and the metal having the same pattern shape as that formed by the aluminum layer corroded by the developer are rinsed with water and dried.

9. The method according to claim 1, characterized in that: The thickness of the aluminum layer is 100 nm.

10. The method according to claim 9, characterized in that The thickness of the photoresist is greater than 1 um.

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