Semiconductor structure and photoetching method

Abstract

The embodiment of the invention provides a semiconductor structure and a photoetching method, and relates to the technical field of photoetching. The semiconductor structure comprises a dielectric film and a transparent substrate, the dielectric film is deposited on the upper surface of the transparent substrate; the thickness of the dielectric film is related to a light incident angle, a light wavelength and the reflectivity of the dielectric film; the dielectric film is used for enhancing the reflection intensity of the transparent substrate to light. Therefore, the dielectric film with the thickness matched with the incident angle of the light, the wavelength of the light and the reflectivity of the dielectric film is deposited on the transparent substrate, so that the reflection intensity of the transparent substrate to the incident light is remarkably enhanced, and a detector of a photoetching machine can capture reflected light from the transparent substrate more clearly; and the positioning precision of the photoetching machine on the transparent substrate is obviously improved, so that the problem of exposure focus offset caused by weak reflected light signals is avoided, and the accuracy of an exposure pattern is ensured.

Description

Technical Field

[0001] The present application relates to the field of photolithography technology, and in particular to a semiconductor structure and a photolithography method. Background Art

[0002] With the advancement of semiconductor manufacturing technology, automatic photolithography machines play a vital role in the chip manufacturing process. One of the key technologies of automatic photolithography machines is that they can automatically find the substrate surface that needs to be exposed. Specifically, this process uses a halogen lamp to irradiate incident light to the substrate surface, and the detector receives the reflected light from the substrate surface. By analyzing the intensity and / or phase of the reflected light, the exposure focus position on the substrate surface can be accurately determined, and then exposure processing and development processing can be performed according to the exposure focus position to form the desired pattern in the photoresist.

[0003] Currently, the processing of opaque substrates by automatic lithography machines is quite mature. However, with the increasing demand for highly transparent materials in the industry, the reflected light from the surface of highly transparent materials is very weak, making it difficult for automatic lithography machines to effectively identify useful reflected light signals. Therefore, when using these transparent substrates, automatic lithography machines are prone to errors in the process of finding the substrate surface, which in turn affects the subsequent exposure process and may cause blurred graphics or exposure failure. Summary of the invention

[0004] Based on the above problems, the present application provides a semiconductor structure and a photolithography method, which can ensure the accuracy of the exposure pattern.

[0005] The embodiments of the present application disclose the following technical solutions:

[0006] In a first aspect, the present application discloses a semiconductor structure, which includes: a dielectric film and a transparent substrate; the dielectric film is deposited on the upper surface of the transparent substrate; the thickness of the dielectric film is related to the incident angle of light, the wavelength of light and the reflectivity of the dielectric film; the dielectric film is used to enhance the reflection intensity of the transparent substrate to light.

[0007] Optionally, the thickness of the dielectric film is as shown in the following formula:

[0008] h'=(kλ / 2n0)*sinθ

[0009] Wherein, h' is the thickness of the dielectric film, k is a positive integer, λ is the wavelength of the light, n0 is the refractive index of the dielectric film, and θ is the incident angle of the light.

[0010] Optionally, the refractive index of the dielectric film is lower than the refractive index of the transparent substrate.

[0011] Optionally, the transparent substrate is any one of a semi-insulating silicon carbide SiC substrate, a quartz substrate and a gallium nitride GaN substrate.

[0012] Optionally, the dielectric film is a silicon nitride SiN film or a silicon monoxide SiO film.

[0013] Optionally, the deposition process of the dielectric film includes any one of chemical vapor deposition, physical vapor deposition and atomic layer deposition.

[0014] Optionally, a photoresist is deposited on the surface of the dielectric film, and the photoresist is used to form a desired pattern during a photolithography process.

[0015] Optionally, the refractive index of the photoresist is lower than the refractive index of the dielectric film.

[0016] Optionally, the semiconductor structure further includes an adhesion layer, wherein the adhesion layer is located between the dielectric film and the transparent substrate, and the adhesion layer is used to enhance the adhesion between the dielectric film and the transparent substrate.

[0017] In a second aspect, the present application discloses a photolithography method, the method comprising:

[0018] By emitting a first light to a surface of a semiconductor structure, and receiving a second light reflected by the semiconductor structure, wherein the semiconductor structure is the structure described in the first aspect, and the first light is light emitted by a halogen lamp;

[0019] Determining an exposure focus position on the semiconductor structure by analyzing the intensity and / or phase of the second light;

[0020] According to the exposure focus position, the semiconductor structure is exposed and developed to form a desired pattern in the photoresist.

[0021] Compared with the prior art, this application has the following beneficial effects:

[0022] The embodiment of the present application provides a semiconductor structure and a photolithography method, the semiconductor structure includes: a dielectric film and a transparent substrate; the dielectric film is deposited on the upper surface of the transparent substrate; the thickness of the dielectric film is related to the incident angle of the light, the wavelength of the light and the reflectivity of the dielectric film; the dielectric film is used to enhance the reflection intensity of the transparent substrate to the light. Therefore, the present application significantly enhances the reflection intensity of the transparent substrate to the incident light by depositing a dielectric film whose thickness matches the incident angle of the light, the wavelength of the light and the reflectivity of the dielectric film on the transparent substrate, so that the detector of the photolithography machine can more clearly capture the reflected light from the transparent substrate, significantly improve the positioning accuracy of the photolithography machine on the transparent substrate, thereby avoiding the problem of exposure focus offset caused by weak reflected light signals, and ensuring the accuracy of the exposure pattern. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present application or the technical solutions in 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 labor.

[0024] Figure 1 A schematic diagram of an automatic photolithography machine for photolithography of a non-transparent substrate and a transparent substrate;

[0025] Figure 2A A schematic diagram of a semiconductor structure provided in an embodiment of the present application;

[0026] Figure 2B A schematic diagram of an anti-reflection film provided in an embodiment of the present application;

[0027] Figure 3 A schematic diagram of a focal plane finding process provided in an embodiment of the present application;

[0028] Figure 4 A schematic diagram of an exposure process provided in an embodiment of the present application;

[0029] Figure 5 A schematic diagram of a development process provided in an embodiment of the present application;

[0030] Figure 6 A flow chart of a photolithography method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0031] With the advancement of semiconductor manufacturing technology, automatic lithography machines play a vital role in the chip manufacturing process. One of the key technologies of automatic lithography machines is that they can automatically find the substrate surface that needs to be exposed. Figure 1 , which is a schematic diagram of an automatic photolithography machine for photolithography of non-transparent substrates and transparent substrates. Figure 1 It can be seen that the current photolithography process for non-transparent substrates is specifically as follows: the incident light emitted by a halogen lamp is used to irradiate the substrate surface of the non-transparent substrate, and then the detector captures the reflected light reflected from the substrate surface of the non-transparent substrate. By precisely analyzing the intensity information and / or phase information of the reflected light, the exposure focus position on the substrate surface can be accurately located, and then exposure processing and development processing can be performed according to the exposure focus position, and finally a pattern that matches the design and has clear edges can be accurately reproduced on the photoresist.

[0032] However, for transparent substrates made of highly transparent materials, the automatic photolithography machine faces great challenges in identifying effective reflected light signals because the highly transparent materials reflect incident light extremely weakly. Specifically, when the halogen lamp is in position (1), the detector can hardly capture any reflected light signals from the substrate surface of the transparent substrate; and when the halogen lamp is moved to position (2), although the detector can sense the reflected light signal, it mistakenly identifies the exposure focus position on the wafer stage. Therefore, when using these transparent substrates, the automatic photolithography machine is prone to errors in the process of finding the substrate surface, which in turn affects the subsequent exposure process and may cause blurred graphics or exposure failure.

[0033] In view of this, the embodiment of the present application provides a semiconductor structure and a photolithography method, the semiconductor structure includes: a dielectric film and a transparent substrate; the dielectric film is deposited on the upper surface of the transparent substrate; the thickness of the dielectric film is related to the incident angle of the light, the wavelength of the light and the reflectivity of the dielectric film; the dielectric film is used to enhance the reflection intensity of the transparent substrate to the light. Therefore, the present application significantly enhances the reflection intensity of the transparent substrate to the incident light by depositing a dielectric film whose thickness matches the incident angle of the light, the wavelength of the light and the reflectivity of the dielectric film on the transparent substrate, so that the detector of the photolithography machine can more clearly capture the reflected light from the transparent substrate, significantly improve the positioning accuracy of the photolithography machine on the transparent substrate, thereby avoiding the problem of exposure focus offset caused by weak reflected light signals, and ensuring the accuracy of the exposure pattern.

[0034] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0035] See also Figure 2A , which is a schematic diagram of a semiconductor structure provided by an embodiment of the present application. The semiconductor structure 20 includes: a dielectric film 21 and a transparent substrate 22.

[0036] First, the transparent substrate 22 of the semiconductor structure 20 is explained:

[0037] The transparent substrate 22 is a highly light-transmitting material, such as a semi-insulating silicon carbide (SiC) substrate, a quartz substrate, or a gallium nitride (GaN) substrate. These highly light-transmitting materials have extremely low light absorption (especially in the visible light and near-ultraviolet light bands), and light can pass through the material almost unimpeded instead of being absorbed or reflected. This makes it difficult for the lithography machine to accurately identify the position of the substrate surface during the focus-finding process, resulting in exposure focus positioning errors.

[0038] Next, the dielectric film 21 is explained:

[0039] The dielectric film 21 is deposited on the upper surface of the transparent substrate 22, and the material is silicon nitride (SiN) or silicon monoxide (SiO). The dielectric film 21 has an appropriate refractive index (the refractive index of silicon nitride is about 2.05, and the refractive index of silicon monoxide is about 1.45-1.5), which can effectively enhance the reflected light signal. Since the refractive index of silicon nitride and silicon monoxide is usually higher than the refractive index of air and lower than the refractive index of the transparent substrate 21, this makes them ideal for making anti-reflection films. The deposition process of the dielectric film 21 includes chemical vapor deposition (CVD), physical vapor deposition (PVD) and atomic layer deposition (ALD). These processes can accurately control the thickness and uniformity of the dielectric film 21 to ensure that the dielectric film 21 has the required optical properties. By adjusting deposition parameters such as deposition rate, temperature and gas flow rate, the thickness of the dielectric film 21 can be accurately controlled.

[0040] The main function of the dielectric film 21 is to enhance the reflection intensity of the incident light by the transparent substrate 22 through the principle of the anti-reflection film. The principle of the anti-reflection film is based on the interference effect of light. When the incident light is incident on the upper surface and the lower surface of the dielectric film 21 (i.e., the interface with the transparent substrate 22), two beams of reflected light will be generated. In the embodiment of the present application, by precisely controlling the thickness of the dielectric film, the optical path difference d of the two beams of reflected light is made to be an even multiple of half the wavelength or an integer multiple of the wavelength, thereby enhancing the intensity of the reflected light.

[0041] See also Figure 2B , this figure is a schematic diagram of an anti-reflection film provided in an embodiment of the present application. Assuming that the refractive index of the dielectric film 21 is n0, after the incident light is incident on the dielectric film 21, two beams of reflected light will be generated on the upper surface and the lower surface of the dielectric film 21 respectively. The optical path difference d of the two reflected light beams is d=2n0h, where h is the light stroke. In order to achieve the anti-reflection effect, the optical path difference d needs to satisfy d=2n0h=kλ, where k is a positive integer and λ is the wavelength of the light. Therefore, the light stroke h is h=kλ / 2n0. It should be noted that due to Figure 2B The incident light is incident perpendicular to the dielectric film 21, so Figure 2B The light path h in is the thickness of the dielectric film 21. Therefore, when k takes different values ​​such as 1, 2, 3, etc., the light path h can correspond to a variety of different values, so that the dielectric film 21 can adapt to different process requirements.

[0042] For example, for dielectric films made of SiN and SiO, if the refractive indices of SiN and SiO are 2.05 and 1.5 respectively, and the wavelength of the halogen lamp light is 590 nm, when k takes different values ​​such as 1, 2, and 3, the light travel h can be as shown in Table 1 below:

[0043] Table 1

[0044]

[0045]

[0046] In practical applications, the incident light of the halogen lamp is usually incident at a certain angle θ to the dielectric film 21. Therefore, it is necessary to consider the effect of the incident angle θ on the thickness h' of the dielectric film. When the light is incident at an angle θ, the relationship between the light stroke h and the thickness h' of the dielectric film satisfies: h'=h×sinθ. Therefore, the thickness h' of the dielectric film is as shown in the following formula (1):

[0047] h'=(kλ / 2n0)*sinθ (1)

[0048] Wherein, h' is the thickness of the dielectric film, k is a positive integer, λ is the wavelength of the light, n0 is the refractive index of the dielectric film, and θ is the incident angle of the light.

[0049] Therefore, formula (1) takes into account the influence of the light incident angle θ on the thickness h′ of the dielectric film 21 , and can ensure that the dielectric film 21 can effectively enhance the reflected light signal under different light incident angles θ.

[0050] For example, when the incident angle θ of the light of the halogen lamp is 45 degrees, the relationship between the thickness h' of the dielectric film made of SiN and SiO and the light travel h can be shown in the following Table 2 and Table 3 respectively:

[0051] Table 2

[0052]

[0053]

[0054] Table 3

[0055] k Light path h_nm SiO thickness (incident angle 45 degrees) h'_nm 1 196.67 139.06 2 393.33 278.13 3 590.00 417.19 4 786.67 556.26 5 983.33 695.32 6 1180.00 834.39 7 1376.67 973.45 8 1573.33 1112.51 9 1770.00 1251.58 10 1966.67 1390.64

[0056] In some specific implementations, a photoresist is deposited on the surface of the dielectric film 21. Photoresist is a photosensitive material used to form a desired pattern in a photolithography process. Through exposure and development, the photoresist can form fine patterns on the substrate surface, which are then used in subsequent etching or deposition processes.

[0057] It should be noted that the refractive index of the dielectric film 21 needs to be lower than the refractive index of the transparent substrate 22. This design is to ensure that when light enters the dielectric film 21 from the photoresist, the reflection loss of the light at the interface between the two is small because the refractive index of the photoresist is lower than the refractive index of the dielectric film 21. According to the Fresnel reflection formula, the reflection loss is related to the difference in refractive index between the two media. The smaller the difference in refractive index, the lower the reflection loss. Therefore, more light can penetrate the photoresist and reach the dielectric film 21, ensuring that the light can effectively enter the dielectric film 21 and participate in the subsequent reflection process.

[0058] The refractive index of the photoresist needs to be lower than the refractive index of the dielectric film 21. This design is to ensure that when light enters the transparent substrate 22 from the dielectric film 21, the light will be strongly reflected at the interface between the two because the refractive index of the dielectric film 21 is lower than the refractive index of the transparent substrate 22. This refractive index difference causes the light to be partially reflected at the interface between the dielectric film 21 and the transparent substrate 22, thereby enhancing the reflected light signal.

[0059] For example, taking the transparent substrate 22 as GaN material, the refractive indexes of various materials may be as shown in Table 4 below:

[0060] Table 4

[0061] Material Refractive Index GaN 2.2 S N 2.0 SiO 1.45-1.5 Photoresist (e.g. AZ5214) 1.56

[0062] It can be seen that the refractive index of the dielectric film 21 is lower than that of the transparent substrate 22, and the refractive index of the photoresist is lower than that of the dielectric film 21. This hierarchical relationship of refractive indices optimizes the propagation path of light, reduces reflection loss, and enhances the reflected light signal, thereby improving the positioning accuracy of the lithography machine and the quality of the exposure pattern.

[0063] It should also be noted that the bonding strength between the dielectric film 21 and the transparent substrate 22 is crucial to the stability and reliability of the device. In order to ensure that the dielectric film 21 can be firmly attached to the transparent substrate 22 and avoid falling off or delamination in subsequent process steps (such as photolithography, etching, ion implantation, etc.), it is often necessary to introduce an adhesion layer between the dielectric film 21 and the transparent substrate 22. The adhesion layer is used to enhance the adhesion between the dielectric film 21 and the transparent substrate 22. During the semiconductor manufacturing process, the dielectric film 21 may be separated from the transparent substrate 22 due to factors such as temperature changes, chemical treatment or mechanical stress. The adhesion layer ensures good contact and adhesion between the dielectric film 21 and the transparent substrate 22 by providing additional bonding strength, thereby improving the stability and reliability of the entire structure.

[0064] Specifically, the material of the adhesion layer is usually selected to be compatible with the dielectric film 21 and the transparent substrate 22, such as silicon dioxide or other materials with good adhesion. These materials usually have low stress, good chemical stability and thermal stability, and a thermal expansion coefficient similar to that of the dielectric film and the transparent substrate, thereby helping to reduce thermal stress caused by temperature changes. In addition, the thickness of the adhesion layer is usually thin to ensure that it does not significantly affect the propagation and reflection effects of light.

[0065] See also Figure 3 , which is a schematic diagram of a focal plane finding process provided by an embodiment of the present application. The purpose of focal plane finding is to determine the surface position of the substrate to ensure that the lens can focus correctly during exposure. If the surface position of the substrate is inaccurate, it will cause blurring, misalignment or size changes in the exposure pattern, seriously affecting the performance and yield of the final chip. Specifically, the photolithography machine emits incident light to the substrate surface through a halogen lamp, and the detector receives the reflected light signal from the substrate surface. By analyzing the intensity information (reflecting the brightness or energy size of the reflected light) and / or phase information (reflecting the phase change of the reflected light waveform) of the reflected light signal, the photolithography machine can accurately determine the surface position of the substrate. In an embodiment of the present application, by depositing a dielectric film whose thickness matches the incident angle of the light, the wavelength of the light, and the reflectivity of the dielectric film on the transparent substrate, the reflection intensity of the incident light of the transparent substrate is significantly enhanced, so that the detector of the photolithography machine can capture the reflected light from the transparent substrate more clearly, significantly improving the positioning accuracy of the photolithography machine on the transparent substrate, thereby avoiding the problem of exposure focus offset caused by weak reflected light signals.

[0066] See also Figure 4 , which is a schematic diagram of an exposure process provided by an embodiment of the present application. During the exposure process, by accurately adjusting the lens focal plane of the lithography machine, it is ensured that the photoresist can be irradiated by the exposure light source at the correct position, thereby forming an accurate pattern. Specifically, once the focus plane finding process is completed, the lens of the lithography machine will accurately adjust its focal plane according to the detected substrate surface position. This focal plane is the plane where the light inside the lens converges, which determines where the light reaches the minimum spot size, i.e., the focus. When the focal plane coincides with the substrate surface, the lithography machine exposes the photoresist through an exposure light source (such as ultraviolet light). Ultraviolet light is widely used in the lithography process because of its short wavelength and high energy. It can penetrate the photoresist and induce a photochemical reaction therein. The photoresist undergoes a photochemical reaction in the exposure area to form a potential pattern. It is understandable that if the focus is offset, even a small offset may cause the photoresist in the exposure area to be unable to be uniformly irradiated by the exposure light source, thereby forming a blurred pattern or exposure failure. The anti-reflection film effect of the dielectric film 21 effectively avoids this problem by improving the precision of the focus finding process and the accuracy of focusing during the exposure process.

[0067] See also Figure 5 , which is a schematic diagram of a development process provided by an embodiment of the present application. The purpose of development is to remove or retain a specific portion of the photoresist through chemical action, thereby forming a pattern corresponding to the mask pattern. Since the lens can focus accurately during the exposure process, the pattern formed by the photoresist after development is the same as the desired shape, with neat edges and high pattern accuracy.

[0068] In summary, the embodiment of the present application provides a semiconductor structure, which includes: a dielectric film and a transparent substrate; the dielectric film is deposited on the upper surface of the transparent substrate; the thickness of the dielectric film is related to the incident angle of the light, the wavelength of the light and the reflectivity of the dielectric film; the dielectric film is used to enhance the reflection intensity of the transparent substrate to the light. Therefore, the present application significantly enhances the reflection intensity of the incident light by the transparent substrate by depositing a dielectric film whose thickness matches the incident angle of the light, the wavelength of the light and the reflectivity of the dielectric film on the transparent substrate, so that the detector of the lithography machine can more clearly capture the reflected light from the transparent substrate, significantly improve the positioning accuracy of the lithography machine on the transparent substrate, thereby avoiding the problem of exposure focus offset caused by weak reflected light signals and ensuring the accuracy of the exposure pattern.

[0069] See also Figure 6 , which is a flow chart of a photolithography method provided in an embodiment of the present application. The method comprises:

[0070] S601: emitting a first light ray toward a surface of a semiconductor structure and receiving a second light ray reflected by the semiconductor structure, wherein the first light ray is light ray emitted by a halogen lamp.

[0071] Among them, the semiconductor structure includes a dielectric film and a transparent substrate; the dielectric film is deposited on the upper surface of the transparent substrate; the thickness of the dielectric film is related to the incident angle of light, the wavelength of light and the reflectivity of the dielectric film; the dielectric film is used to enhance the reflection intensity of the transparent substrate to light.

[0072] In some specific implementations, the thickness of the dielectric film is as shown in the following formula (2):

[0073] h'=(kλ / 2n0)*sinθ (2)

[0074] Wherein, h' is the thickness of the dielectric film, k is a positive integer, λ is the wavelength of the light, n0 is the refractive index of the dielectric film, and θ is the incident angle of the light.

[0075] In some specific implementations, the refractive index of the dielectric film is lower than the refractive index of the transparent substrate.

[0076] In some specific implementations, the transparent substrate is any one of a semi-insulating silicon carbide SiC substrate, a quartz substrate, and a gallium nitride GaN substrate.

[0077] In some specific implementations, the dielectric film is a silicon nitride SiN film or a silicon monoxide SiO film.

[0078] In some specific implementations, the deposition process of the dielectric film includes any one of chemical vapor deposition, physical vapor deposition and atomic layer deposition.

[0079] In some specific implementations, a photoresist is deposited on the surface of the dielectric film, and the photoresist is used to form a desired pattern during a photolithography process.

[0080] In some specific implementations, the refractive index of the photoresist is lower than the refractive index of the dielectric film.

[0081] In some specific implementations, the semiconductor structure further includes an adhesion layer, which is located between the dielectric film and the transparent substrate, and is used to enhance adhesion between the dielectric film and the transparent substrate.

[0082] S602: Determine an exposure focus position on the semiconductor structure by analyzing the intensity and / or phase of the second light.

[0083] S603: performing exposure processing and development processing on the semiconductor structure according to the exposure focus position to form a desired pattern in the photoresist.

[0084] In summary, the embodiments of the present application provide a lithography method, which significantly enhances the reflection intensity of the transparent substrate to the incident light by depositing a dielectric film whose thickness matches the incident angle of the light, the wavelength of the light and the reflectivity of the dielectric film on the transparent substrate, so that the detector of the lithography machine can more clearly capture the reflected light from the transparent substrate, significantly improves the positioning accuracy of the lithography machine on the transparent substrate, thereby avoiding the exposure focus offset problem caused by weak reflected light signals and ensuring the accuracy of the exposure pattern.

[0085] Although the subject matter has been described in language specific to structural features and / or methodological logical actions, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or actions described above. On the contrary, the specific features and actions described above are merely example forms of implementing the claims.

[0086] Although several specific implementation details are included in the above discussion, these should not be interpreted as limiting the scope of the present application. Certain features described in the context of a separate embodiment can also be implemented in a single embodiment in combination. On the contrary, the various features described in the context of a single embodiment can also be implemented in multiple embodiments individually or in any suitable sub-combination.

[0087] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of disclosure involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above disclosed concept. For example, the above features are replaced with the technical features with similar functions disclosed in this application (but not limited to) by each other to form a technical solution.

Claims

1. A semiconductor structure, characterized in that: The semiconductor structure comprises: a dielectric film and a transparent substrate; the dielectric film is deposited on the upper surface of the transparent substrate; the thickness of the dielectric film is related to the incident angle of light, the wavelength of light and the reflectivity of the dielectric film; the dielectric film is used to enhance the reflection intensity of the transparent substrate to light.

2. The semiconductor structure according to claim 1, characterized in that: The thickness of the dielectric film is shown in the following formula: h'=(kλ / 2n0)*sinθ Wherein, h' is the thickness of the dielectric film, k is a positive integer, λ is the wavelength of the light, n0 is the refractive index of the dielectric film, and θ is the incident angle of the light.

3. The semiconductor structure according to claim 1, characterized in that: The refractive index of the dielectric film is lower than the refractive index of the transparent substrate.

4. The semiconductor structure according to claim 1, characterized in that The transparent substrate is any one of a semi-insulating silicon carbide SiC substrate, a quartz substrate and a gallium nitride GaN substrate.

5. The semiconductor structure according to claim 1, characterized in that: The dielectric film is a silicon nitride SiN film or a silicon monoxide SiO film.

6. The semiconductor structure according to claim 1, characterized in that The deposition process of the dielectric film includes any one of chemical vapor deposition, physical vapor deposition and atomic layer deposition.

7. The semiconductor structure according to any one of claims 1 to 6, characterized in that: A photoresist is deposited on the surface of the dielectric film, and the photoresist is used to form a required pattern during a photolithography process.

8. The semiconductor structure according to claim 7, characterized in that: The refractive index of the photoresist is lower than the refractive index of the dielectric film.

9. The semiconductor structure according to claim 1, characterized in that: The semiconductor structure further includes an adhesion layer, which is located between the dielectric film and the transparent substrate, and is used to enhance the adhesion between the dielectric film and the transparent substrate.

10. A photolithography method, characterized in that: The method comprises: By emitting a first light to a surface of a semiconductor structure, and receiving a second light reflected by the semiconductor structure, wherein the semiconductor structure is the structure of claim 7, and the first light is light emitted by a halogen lamp; Determining an exposure focus position on the semiconductor structure by analyzing the intensity and / or phase of the second light; According to the exposure focus position, the semiconductor structure is exposed and developed to form a desired pattern in the photoresist.

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