Method for manufacturing y-gate and y-gate manufactured thereby

Abstract

The disclosure provides a preparation method of a Y-shaped gate and a Y-shaped gate prepared by the method, and can be applied to the field of microelectronics technology. The method comprises the following steps: performing deep ultraviolet light irradiation treatment on a first electron beam photoresist located on the upper surface of a substrate to obtain a first photoresist layer; spin coating a second electron beam photoresist on the surface of the first photoresist layer to obtain a second photoresist layer; performing a first exposure and development operation on the first photoresist layer and the second photoresist layer to obtain a gate cap structure of the Y-shaped gate; performing a second exposure and development operation on the first photoresist layer after the first exposure and development operation to obtain a gate leg structure of the Y-shaped gate; and filling a target metal material into the gate cap structure and the gate leg structure by using a metal evaporation method to obtain the Y-shaped gate.

Description

Technical Field

[0001] This disclosure relates to the field of microelectronics technology, and in particular to a method for fabricating a Y-type gate and the fabricated Y-type gate. Background Technology

[0002] In semiconductor technology, the morphology of the metal gate in a field-effect transistor (FET) not only alters the gate resistance but also affects the parasitic capacitance between the gate and the source / drain, thus significantly impacting the device's operating frequency and noise. Currently, T-shaped and Y-shaped gates are primarily used to reduce parasitic effects between the gate and the source / drain, thereby improving device performance. Compared to T-shaped gates, Y-shaped gates offer higher mechanical strength and lower parasitic capacitance, thus showing greater application potential.

[0003] However, compared to the mature fabrication process of T-type gates, the fabrication of Y-type gates faces challenges such as fewer fabrication schemes, higher process requirements, and greater fabrication difficulty. Summary of the Invention

[0004] In view of the above problems, this disclosure provides a method for preparing a Y-type gate and the prepared Y-type gate.

[0005] According to a first aspect of this disclosure, a method for fabricating a Y-type gate is provided, comprising:

[0006] The first electron beam photoresist located on the upper surface of the substrate is subjected to deep ultraviolet light irradiation to obtain the first photoresist layer;

[0007] A second electron beam photoresist is spin-coated onto the surface of the first photoresist layer to obtain a second photoresist layer, wherein the sensitivity of the second electron beam photoresist is higher than that of the first electron beam photoresist.

[0008] The first photoresist layer and the second photoresist layer are subjected to a first exposure and development operation to obtain the gate cap structure of the Y-shaped gate;

[0009] A second exposure and development operation is performed on the first photoresist layer after the first exposure and development operation described above to obtain the gate pin structure of the Y-shaped gate described above.

[0010] The target metal material is filled into the above-mentioned gate cap structure and gate foot structure using a metal evaporation method to obtain the above-mentioned Y-shaped gate.

[0011] According to embodiments of this disclosure, the first electron beam photoresist located on the upper surface of the substrate is subjected to deep ultraviolet light irradiation to obtain a first photoresist layer, comprising:

[0012] By using the aforementioned deep ultraviolet light irradiation treatment, the molecular weight of the first electron beam photoresist is degraded to obtain the first photoresist layer, wherein the degree of degradation of the molecular weight of the first electron beam photoresist in the first photoresist layer gradually decreases from top to bottom.

[0013] According to embodiments of this disclosure, the first exposure and development operation on the first photoresist layer and the second photoresist layer to obtain the Y-shaped gate cap structure includes:

[0014] Based on the first exposure size set for the second photoresist layer, the second photoresist layer is exposed to obtain the first exposure area of ​​the second photoresist layer.

[0015] The first exposure area is developed to obtain the developed structure of the second photoresist layer and the gate cap structure of the first photoresist layer.

[0016] According to embodiments of this disclosure, the above-described development operation on the first exposure area to obtain the developed structure of the second photoresist layer and the gate cap structure of the first photoresist layer includes:

[0017] Using a first developer, the first exposed area of ​​the second photoresist layer is developed to obtain the developed structure of the second photoresist layer; and

[0018] After obtaining the above-mentioned developing structure, the first photoresist layer is developed using the first developing solution based on the degree of degradation of the molecular weight of the first electron beam photoresist in the first photoresist layer to obtain the above-mentioned gate cap structure, wherein the gate cap structure is an inverted trapezoidal structure.

[0019] According to embodiments of this disclosure, the second exposure and development operation is performed on the first photoresist layer after the first exposure and development operation to obtain the gate pin structure of the Y-shaped gate, including:

[0020] Based on the second exposure size set for the first photoresist layer, the first photoresist layer after the first exposure and development operation is exposed to obtain the second exposure area of ​​the second photoresist layer.

[0021] The second exposure area is developed using a second developer to obtain the aforementioned gate pin structure.

[0022] According to embodiments of this disclosure, the target metal material includes a first target metal material and a second target metal material. Using a metal evaporation method, the target metal material is filled into the gate cap structure and the gate foot structure to obtain the Y-shaped gate, comprising:

[0023] An adhesion layer made of the first target metal material is formed on the substrate surface located in the above-mentioned gate pin structure using a metal evaporation method.

[0024] Using the metal evaporation method described above, the second target metal material is filled into the gate cap structure and the gate foot structure to obtain a target structure, wherein the target structure includes the Y-shaped gate composed of the first target metal material and the second target metal material.

[0025] According to embodiments of this disclosure, the method for fabricating the Y-type gate further includes:

[0026] The Y-shaped gate is obtained by peeling off the first photoresist layer, the second photoresist layer, and the metal layer on the second photoresist layer obtained by the metal evaporation method in the target structure.

[0027] According to embodiments of this disclosure, the selection of the first target metal material is related to the material of the substrate.

[0028] According to an embodiment of this disclosure, the thickness of the first photoresist layer is greater than the thickness of the Y-shaped gate, and the first electron beam photoresist is a PMMA photoresist.

[0029] According to a second aspect of this disclosure, a Y-type gate prepared by the above-described method for preparing a Y-type gate is provided.

[0030] According to the Y-type gate fabrication method and the fabricated Y-type gate provided in this disclosure, a first electron beam photoresist located on the upper surface of a substrate is subjected to deep ultraviolet light irradiation to obtain a first photoresist layer. The molecular weight of the first electron beam photoresist is then degraded by deep ultraviolet light irradiation. A second electron beam photoresist is then spin-coated onto the surface of the first photoresist layer to obtain a second photoresist layer. The second electron beam photoresist has a higher sensitivity than the first electron beam photoresist. This dual-layer photoresist process avoids the mutual interference between photoresists caused by multi-layer photoresist processes. Furthermore, the first photoresist layer after deep ultraviolet light irradiation... The molecular weight of the electron beam photoresist gradually decreases from top to bottom. The first and second photoresist layers are subjected to a first exposure and development operation to obtain the gate cap structure of the Y-shaped gate. Then, the first photoresist layer after the first exposure and development operation is subjected to a second exposure and development operation to obtain the gate foot structure of the Y-shaped gate. Since the exposure and development operation is performed directly on the first photoresist layer after the first exposure and development operation, the photoresist thickness during gate foot exposure is reduced, and smaller gate feet can be fabricated. Finally, the target metal material is filled into the gate cap structure and gate foot structure using a metal evaporation method to obtain the Y-shaped gate. Attached Figure Description

[0031] The foregoing contents, as well as other objects, features, and advantages of this disclosure, will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0032] Figure 1 A flowchart illustrating a method for fabricating a Y-type gate according to an embodiment of the present disclosure is shown schematically.

[0033] Figure 2 This schematic diagram illustrates a deep ultraviolet light irradiation process of a first electron beam photoresist according to an embodiment of the present disclosure;

[0034] Figure 3 A schematic diagram illustrating a substrate, a first photoresist layer, and a second photoresist layer according to an embodiment of the present disclosure is shown.

[0035] Figure 4 This schematically illustrates a diagram of the cap structure of the Y-shaped grid obtained after the first exposure and development operation according to an embodiment of the present disclosure;

[0036] Figure 5 This schematically illustrates a diagram of the Y-shaped grid pin structure obtained after a second exposure and development operation according to an embodiment of the present disclosure;

[0037] Figure 6 This schematic diagram illustrates a metal evaporation process according to an embodiment of the present disclosure.

[0038] Figure 7 A schematic diagram of a Y-shaped gate according to an embodiment of the present disclosure is shown. Detailed Implementation

[0039] The embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the present disclosure for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.

[0040] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0041] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0042] When using expressions such as "at least one of A, B, and C", they should generally be interpreted in accordance with the meaning that is commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, and C" should include, but is not limited to, a system having A alone, a system having B alone, a system having C alone, a system having A and B, a system having A and C, a system having B and C, and / or a system having A, B, and C, etc.).

[0043] In the technical solutions disclosed herein, the collection, storage, use, processing, transmission, provision, disclosure, and application of data (including but not limited to user personal information) comply with the provisions of relevant laws and regulations, necessary confidentiality measures have been taken, and they do not violate public order and good morals.

[0044] In implementing this disclosure, it was discovered that among the many factors affecting the performance of high electron mobility transistors (HEMTs), the length and morphology of the gate are of paramount importance for improving the device's operating frequency and suppressing noise. The Y-type gate, with its large cross-sectional area, small gate lead size, and relatively large distance between the gate cap and the source / drain, not only reduces gate resistance but also effectively decreases parasitic capacitance between the gate and the source / drain, thus contributing to the device's high-frequency characteristics. Currently, deep submicron Y-type gates in HEMTs are all achieved using electron beam lithography. Specific techniques include controlling the electron beam exposure method, utilizing the anisotropic etching characteristics of crystal materials, and using electron beam resists of different sensitivities. However, related technologies for Y-type gate fabrication suffer from limited fabrication options, high process requirements, extremely high requirements for electron beam resists, and significant fabrication difficulties.

[0045] Therefore, embodiments of this disclosure provide a method for fabricating a Y-type gate, comprising: subjecting a first electron beam photoresist located on the upper surface of a substrate to deep ultraviolet light irradiation to obtain a first photoresist layer; spin-coating a second electron beam photoresist onto the surface of the first photoresist layer to obtain a second photoresist layer, wherein the sensitivity of the second electron beam photoresist is higher than that of the first electron beam photoresist; performing a first exposure and development operation on the first and second photoresist layers to obtain a gate cap structure of the Y-type gate; performing a second exposure and development operation on the first photoresist layer after the first exposure and development operation to obtain a gate foot structure of the Y-type gate; and filling the gate cap structure and gate foot structure with a target metal material using a metal evaporation method to obtain a Y-type gate.

[0046] The following is passed Figures 1 to 7 The method for fabricating the Y-type gate according to the embodiments of this disclosure will be described in detail.

[0047] Figure 1 A flowchart illustrating a method for fabricating a Y-shaped gate according to an embodiment of the present disclosure is shown schematically.

[0048] like Figure 1 As shown, the method 100 includes operations S110 to S150.

[0049] In operation S110, the first electron beam photoresist located on the upper surface of the substrate is subjected to deep ultraviolet light irradiation to obtain the first photoresist layer.

[0050] According to embodiments of this disclosure, a first electron beam photoresist can be spin-coated onto a substrate surface and then baked. For example, a hot plate can be used for baking, the baking temperature can be set to 180°C, and the baking time can be set to 2-3 minutes.

[0051] According to embodiments of this disclosure, a first electron beam photoresist can be subjected to deep ultraviolet (DUV) irradiation. DUV light has a certain photolytic effect on the first electron beam photoresist, degrading the high molecules in the first electron beam photoresist into low molecules. For example, the power of the light source used for DUV irradiation can be set to 60W, and the irradiation time can be set to 1 hour; alternatively, the power of the light source used for DUV irradiation can also be set between 40-70W, and the irradiation time can be set between 0.5-2 hours depending on the selection of the light source power.

[0052] In operation S120, a second electron beam photoresist is spin-coated onto the surface of the first photoresist layer to obtain the second photoresist layer.

[0053] According to embodiments of this disclosure, a second electron beam photoresist can be spin-coated onto the surface of a first photoresist after deep ultraviolet light irradiation, and the second electron beam photoresist can be baked. For example, a hot plate can be used for baking, the baking temperature can be set to 180°C, and the baking time can be set to 2 minutes.

[0054] According to embodiments of this disclosure, the sensitivity of the second electron beam photoresist needs to be higher than that of the first electron beam photoresist. This means the second electron beam photoresist requires a smaller photosensitive dose compared to the first electron beam photoresist, resulting in easier electron beam exposure. Therefore, less electron beam is needed to expose the second electron beam photoresist. Consequently, the first electron beam photoresist, with lower sensitivity, is placed in the first layer to obtain the first photoresist layer; and the second electron beam photoresist, with higher sensitivity, is placed in the second layer to obtain the second photoresist layer.

[0055] In operation S130, the first exposure and development operation is performed on the first and second photoresist layers to obtain the gate cap structure of the Y-shaped gate.

[0056] According to embodiments of this disclosure, an electron beam lithography machine can be used to expose the first photoresist layer and the second photoresist layer according to the preset size of the second photoresist layer to be exposed and the preset exposure dose. After exposure, the first and second photoresist layers are developed with a developer, fixed with a fixer, and dried to obtain a Y-shaped gate cap structure.

[0057] According to embodiments of this disclosure, the preset size of the second photoresist layer to be exposed can characterize the size of the opening required in the second photoresist layer. The opening in the second photoresist layer is merely a window to allow subsequent exposure and development of the first photoresist layer directly through this opening. The preset exposure dose can characterize the preset number of electron beams.

[0058] In operation S140, the first photoresist layer, after the first exposure and development operation, is subjected to a second exposure and development operation to obtain the gate pin structure of the Y-shaped gate.

[0059] According to embodiments of this disclosure, after the first exposure and development operation, the first photoresist layer can be directly exposed and developed through the opening of the second photoresist layer to obtain the gate pin structure of the Y-shaped gate.

[0060] According to embodiments of this disclosure, an electron beam lithography machine can be used to expose the first photoresist layer after the first exposure and development operation according to the preset gate pin size and preset exposure dose, and then develop the exposed second photoresist layer with a developer, fix it with a fixer, and blow it dry to obtain the gate pin structure of the Y-shaped gate.

[0061] In operation S150, the target metal material is filled into the grid cap structure and grid foot structure using a metal evaporation method to obtain a Y-shaped grid.

[0062] According to embodiments of this disclosure, a target metal material can be filled into the obtained gate cap structure and gate foot structure using a metal evaporation method to obtain a Y-shaped gate. The obtained gate cap structure and gate foot structure are equivalent to models of the desired Y-shaped gate.

[0063] According to embodiments of this disclosure, a first electron beam photoresist located on the upper surface of a substrate is subjected to deep ultraviolet light irradiation to obtain a first photoresist layer. The molecular weight of the first electron beam photoresist is then degraded by deep ultraviolet light irradiation. A second electron beam photoresist is then spin-coated onto the surface of the first photoresist layer to obtain a second photoresist layer. The second electron beam photoresist has a higher sensitivity than the first electron beam photoresist. This dual-layer photoresist process facilitates the fabrication of the Y-type gate, avoiding the mutual interference between photoresists present in multi-layer photoresist processes. Furthermore, the first electron beam photoresist in the first photoresist layer after deep ultraviolet light irradiation... The degree of molecular weight degradation gradually decreases from top to bottom. The first and second photoresist layers are subjected to a first exposure and development operation to obtain the gate cap structure of the Y-shaped gate. Then, the first photoresist layer after the first exposure and development operation is subjected to a second exposure and development operation to obtain the gate foot structure of the Y-shaped gate. Since the exposure and development operation is performed directly on the first photoresist layer after the first exposure and development operation, the photoresist thickness during gate foot exposure is reduced, and smaller gate feet can be fabricated. Finally, the target metal material is filled into the gate cap structure and gate foot structure using a metal evaporation method to obtain the Y-shaped gate.

[0064] According to embodiments of this disclosure, the thickness of the first photoresist layer is greater than the thickness of the Y-shaped gate, and the first electron beam photoresist is PMMA photoresist.

[0065] According to embodiments of this disclosure, the first electron beam photoresist can be a PMMA (Poly Methyl Methacrylate) photoresist, for example, the first electron beam photoresist can be PMMA950 or PMMA495. PMMA photoresist has a longer molecular weight and is more resistant to degradation by deep ultraviolet light.

[0066] According to embodiments of this disclosure, the Y-shaped gate is fabricated within the first photoresist layer. Therefore, the thickness of the first photoresist layer must be greater than the thickness of the Y-shaped gate to be fabricated. The second photoresist layer is used to create an opening so that the first photoresist layer can be directly exposed and developed in a second exposure operation. Therefore, the thickness of the second photoresist layer can be appropriate. For example, the thickness of the first photoresist layer can be set to 550-650 nm, and the thickness of the second photoresist layer can be set to 200-300 nm.

[0067] According to embodiments of this disclosure, since the sensitivity of the second electron beam photoresist is higher than that of the first electron beam photoresist, the second electron beam photoresist can be selected from electron beam photoresists with higher sensitivity than PMMA photoresist. For example, the second electron beam photoresist can be ZEP520 photoresist.

[0068] According to embodiments of this disclosure, the thickness of the first photoresist layer is greater than the thickness of the Y-shaped gate, which allows the Y-shaped gate to be formed in the first photoresist layer. The first electron beam photoresist is a PMMA photoresist, which allows the molecular weight of the first electron beam photoresist to be degraded to a certain extent after being treated with deep ultraviolet light, so as to facilitate subsequent exposure and development operations.

[0069] According to an embodiment of this disclosure, a first electron beam photoresist located on the upper surface of a substrate is subjected to deep ultraviolet light irradiation to obtain a first photoresist layer, comprising: using deep ultraviolet light irradiation to degrade the molecular weight of the first electron beam photoresist to obtain a first photoresist layer, wherein the degree of degradation of the molecular weight of the first electron beam photoresist in the first photoresist layer gradually decreases from top to bottom.

[0070] According to the embodiments of this disclosure, the first photoresist layer has a certain thickness. The treatment with deep ultraviolet light is because deep ultraviolet light has a photodegradation effect on the polymer in the first electron beam photoresist, which can break the polymer chains in the first electron beam photoresist to obtain low molecular chains, that is, degrade the polymer into low molecules.

[0071] According to embodiments of this disclosure, since the first photoresist layer has a certain thickness, the intensity of deep ultraviolet light irradiating the surface of the first photoresist layer will be stronger. As the depth increases, the light intensity received by the first electron beam photoresist in the first photoresist layer decreases, resulting in less damage to the polymer chains. Ultimately, the first electron beam photoresist closer to the surface of the first photoresist layer decomposes more strongly, while the decomposition of the first electron beam photoresist in the lower layers decreases. Therefore, in the subsequent first exposure and development operation, since the degree of molecular weight degradation of the first electron beam photoresist in the first photoresist layer gradually decreases from top to bottom, the degree of development of the first electron beam photoresist in the first photoresist layer also gradually decreases from top to bottom. This results in the width of the structure in the first photoresist layer obtained after the first exposure and development operation gradually decreasing from top to bottom, thus forming an inverted trapezoid, which yields a gate cap structure conforming to a Y-type gate.

[0072] According to embodiments of this disclosure, assuming the first electron beam photoresist is not subjected to deep ultraviolet light irradiation, the first photoresist layer will not show a pattern during the subsequent first exposure and development operation, i.e., it will not be developed. Since deep ultraviolet light reduces the molecular weight of the first electron beam photoresist, it will be dissolved to some extent by the developer during development, resulting in the corresponding pattern. If the polymer chains of the first electron beam photoresist are not completely destroyed, the developer has no effect on the first electron beam photoresist during the first exposure and development operation, and the corresponding pattern will not be dissolved. However, after deep ultraviolet light irradiation, some of the polymer chains in the first electron beam photoresist are destroyed, and the developer will partially dissolve the first electron beam photoresist. The dissolution is stronger closer to the surface of the first electron beam photoresist layer and weaker towards the bottom, thus resulting in an inverted trapezoidal structure that is wider at the top and narrower at the bottom.

[0073] According to embodiments of this disclosure, deep ultraviolet light irradiation is used to degrade the molecular weight of the first electron beam photoresist, resulting in a first photoresist layer. During subsequent exposure and development operations, the developer partially dissolves the first electron beam photoresist. The first electron beam photoresist closer to the surface of the first photoresist layer dissolves more strongly, while the first electron beam photoresist further down dissolves less strongly, thus obtaining an inverted trapezoidal structure that is wider at the top and narrower at the bottom.

[0074] Figure 2 The illustration shows a schematic diagram of deep ultraviolet light irradiation of a first electron beam photoresist according to an embodiment of the present disclosure.

[0075] like Figure 2 As shown, the first layer is a substrate layer, and the second layer is a first electron beam photoresist spin-coated on the surface of the substrate. The first electron beam photoresist can be a PMMA photoresist.

[0076] According to an embodiment of this disclosure, a first photoresist layer can be obtained by subjecting a first electron beam photoresist located on the upper surface of a substrate to deep ultraviolet light irradiation (DUV). This is equivalent to performing the above-described operation S110.

[0077] Figure 3 A schematic diagram of a substrate, a first photoresist layer, and a second photoresist layer according to an embodiment of the present disclosure is shown.

[0078] According to embodiments of this disclosure, the first photoresist layer on the substrate layer can be PMMA photoresist, and the second photoresist layer on the substrate layer can be ZEP photoresist.

[0079] According to embodiments of this disclosure, the sensitivity of the second photoresist layer needs to be higher than that of the first photoresist layer, meaning the first photoresist layer requires a higher electron beam dose than the second photoresist layer. If the first photoresist layer requires a lower electron beam dose than the second photoresist layer, the first photoresist layer will be dissolved through by the developer during the first exposure and development operation, preventing the formation of a gate cap structure on the first photoresist layer and eliminating the need for a second exposure and development operation.

[0080] According to embodiments of this disclosure, by performing the above-described operations S110 and S120, the following can be obtained: Figure 3 The substrate, the first photoresist layer, and the second photoresist layer are shown.

[0081] According to embodiments of this disclosure, a first exposure and development operation is performed on a first photoresist layer and a second photoresist layer to obtain a Y-shaped gate cap structure, including: exposing the second photoresist layer based on a first exposure size set for the second photoresist layer to obtain a first exposure area of ​​the second photoresist layer; and developing the first exposure area to obtain a developed structure of the second photoresist layer and a gate cap structure of the first photoresist layer.

[0082] According to embodiments of this disclosure, the photoresist in the exposed area can be dissolved using a developer; however, the photoresist in the unexposed area cannot be dissolved by the developer.

[0083] According to embodiments of this disclosure, based on a first exposure size set for the second photoresist layer, an exposure operation is performed on the second photoresist layer to obtain a first exposure area of ​​the second photoresist layer. The first exposure size characterizes the size of the required opening in the second photoresist layer. For the second photoresist layer, only the portion exposed by the electron beam will be developed using the developing solution. Therefore, by performing a developing operation on the first exposure area, a developed structure portion corresponding to the first exposure area can be obtained in the second photoresist layer.

[0084] According to embodiments of this disclosure, the first exposure size is consistent with the required opening size of the second photoresist layer. For example, if the required opening size of the second photoresist layer is 30nm × 20nm, then the first exposure size can be set to 30nm × 20nm.

[0085] According to embodiments of this disclosure, the developer also has a certain dissolving effect on the first electron beam photoresist irradiated by deep ultraviolet light. The stronger the intensity of deep ultraviolet light irradiation, the greater the degree of molecular weight degradation of the photoresist, and the easier it is to be dissolved by the developer.

[0086] According to embodiments of this disclosure, during the deep ultraviolet irradiation process of the first electron beam photoresist, as the depth of the first photoresist layer increases, the irradiation intensity of the deep ultraviolet light on the first electron beam photoresist in the first photoresist layer decreases. Consequently, the developer has a greater degree of dissolution of the first electron beam photoresist closer to the surface of the first photoresist layer. At the same time, since the developer takes longer to dissolve the top layer of the first photoresist layer than the bottom layer, the dissolution area expands to both ends, making the upper width of the inverted trapezoid formed wider than the width of the opening of the second photoresist layer, thereby obtaining a Y-shaped gate cap structure.

[0087] According to embodiments of this disclosure, the exposed photoresist can be developed with a developer, fixed with a fixer, and then dried to obtain the Y-shaped gate cap structure. For example, the developer can be N50, and the development time can be set to 3-4 minutes. The fixer can be isopropyl alcohol (IPA), and the fixing time can be set to 30-60 seconds. After drying with nitrogen, the developed structure and the gate cap structure are obtained. The selection of the developer and fixer is related to the selection of the photoresist.

[0088] According to embodiments of this disclosure, based on a first exposure size set for the second photoresist layer, an exposure operation is performed on the second photoresist layer to obtain a first exposure area of ​​the second photoresist layer. Then, by performing a development operation on the first exposure area, a development structure of the second photoresist layer and a gate cap structure of the first photoresist layer can be obtained.

[0089] Figure 4 A schematic diagram of the cap structure of the Y-shaped grid obtained after the first exposure and development operation according to an embodiment of the present disclosure is shown.

[0090] like Figure 4 As shown, the structure obtained after development in the second photoresist layer (ZEP) is the developed structure, which means that an opening is obtained in the second photoresist layer. The structure obtained after development in the first photoresist layer (PMMA) is the gate cap structure of a Y-shaped gate.

[0091] According to embodiments of this disclosure, since the first photoresist layer has a certain thickness, the intensity of deep ultraviolet light irradiating the surface of the first photoresist layer will be stronger. As the depth increases, the light intensity received by the first electron beam photoresist in the first photoresist layer decreases, resulting in less damage to the polymer chains. Ultimately, the first electron beam photoresist closer to the surface of the first photoresist layer decomposes more strongly, while the decomposition of the first electron beam photoresist in the lower layers decreases. Therefore, in the subsequent first exposure and development operation, since the degree of molecular weight degradation of the first electron beam photoresist in the first photoresist layer gradually decreases from top to bottom, the degree of development of the first electron beam photoresist in the first photoresist layer also gradually decreases from top to bottom. This results in the width of the structure in the first photoresist layer obtained after the first exposure and development operation gradually decreasing from top to bottom, thus forming an inverted trapezoid, which yields a gate cap structure conforming to a Y-type gate.

[0092] According to embodiments of this disclosure, by performing the above-described operation S130, the following can be obtained: Figure 4 The developing structure and grid cap structure are shown.

[0093] According to embodiments of this disclosure, a development operation is performed on a first exposure area to obtain a developed structure of a second photoresist layer and a gate cap structure of a first photoresist layer. This includes: using a first developer to develop the first exposure area of ​​the second photoresist layer to obtain a developed structure of the second photoresist layer; and after obtaining the developed structure, using the first developer, based on the degree of degradation of the molecular weight of the first electron beam photoresist in the first photoresist layer, to develop the first photoresist layer to obtain a gate cap structure, wherein the gate cap structure is an inverted trapezoidal structure.

[0094] According to the embodiments of this disclosure, since only the area exposed in the second photoresist layer will be developed during the development process, the first developing solution can be used to develop the first exposed area of ​​the second photoresist layer to obtain the developed structure of the second photoresist layer.

[0095] According to embodiments of this disclosure, during the deep ultraviolet irradiation process of the first electron beam photoresist, the deeper the first photoresist layer, the weaker the irradiation intensity of the deep ultraviolet light on the first electron beam photoresist in the first photoresist layer. Therefore, the first developer has a greater degree of dissolution on the first electron beam photoresist closer to the surface of the first photoresist layer, thereby obtaining an inverted trapezoidal gate cap structure. For example, the first developer can be N50. The choice of the first developer is related to the choice of photoresist.

[0096] According to embodiments of this disclosure, since the molecular weight of the first electron beam photoresist in the first photoresist layer gradually decreases from top to bottom, during the development process, the developer has a greater degree of dissolution on the first electron beam photoresist closer to the surface of the first photoresist layer, thereby obtaining an inverted trapezoidal gate cap structure.

[0097] According to an embodiment of this disclosure, a second exposure and development operation is performed on the first photoresist layer after the first exposure and development operation to obtain a Y-shaped gate pin structure. The method includes: exposing the first photoresist layer after the first exposure and development operation based on a second exposure size set for the first photoresist layer to obtain a second exposure area of ​​the second photoresist layer; and developing the second exposure area using a second developer to obtain the gate pin structure.

[0098] According to embodiments of this disclosure, based on a second exposure size set for the first photoresist layer, the first photoresist layer after the first exposure and development operation can be exposed to obtain a second exposure area of ​​the second photoresist layer. Then, a second developer is used to develop the second exposure area, thereby obtaining a gate pin structure. The second exposure size is consistent with the size of the gate pin to be fabricated. For example, if the desired gate pin size is 30nm × 20nm, the second exposure size can be set to 30nm × 20nm.

[0099] According to embodiments of this disclosure, the first photoresist layer after exposure can be developed with a developer, fixed with a fixer, and then dried to obtain the Y-shaped gate pin structure. For example, the developer can be MIBK:IPA (1:3), the development time can be set to 40-60 seconds, the fixer can be isopropanol, the fixing time can be set to 30-60 seconds, and then dried with nitrogen to obtain the gate pin structure.

[0100] According to embodiments of this disclosure, since the exposure and development operation is performed directly on the first photoresist layer after the first exposure and development operation, the photoresist thickness during gate exposure is reduced, thereby enabling the fabrication of smaller gates.

[0101] Figure 5 A schematic diagram of the Y-shaped grid pin structure obtained after a second exposure and development operation according to an embodiment of the present disclosure is shown.

[0102] like Figure 5 As shown, the first photoresist layer after the first exposure and development operation can be directly exposed and developed through the opening area (development structure part) on the second photoresist layer to obtain the gate foot structure under the gate cap structure in the first photoresist layer.

[0103] According to embodiments of this disclosure, such as Figure 5The inverted trapezoidal structure in the first photoresist layer is the gate cap structure of the Y-shaped gate, and the rectangular area below it is the gate foot structure of the Y-shaped gate. Figure 5 All the developed structures in the first photoresist layer are complete Y-shaped gate structures.

[0104] According to embodiments of this disclosure, by performing the above-described operation S140, the following can be obtained: Figure 5 The complete Y-shaped grid structure is shown.

[0105] According to embodiments of this disclosure, the target metal material may include a first target metal material and a second target metal material. A metal evaporation method is used to fill the target metal material into the gate cap structure and the gate foot structure to obtain a Y-shaped gate. This includes: forming an adhesion layer composed of the first target metal material on the substrate surface located in the gate foot structure using a metal evaporation method; and filling the gate cap structure and the gate foot structure with the second target metal material using a metal evaporation method to obtain a target structure. The target structure may include a Y-shaped gate composed of the first target metal material and the second target metal material.

[0106] According to embodiments of this disclosure, a metal evaporation method can be used to first form an adhesion layer made of a first target metal material on the substrate surface located in the gate foot structure, and then a second target metal material can be filled into the gate cap structure and the gate foot structure using the metal evaporation method to obtain the target structure.

[0107] According to embodiments of this disclosure, the obtained Y-shaped gate can be composed of a first target metal material and a second target metal material. The second target metal material may include at least one metal material, and each metal material can be sequentially filled into the gate cap structure and the gate foot structure using a metal evaporation method as required, thereby obtaining the Y-shaped gate.

[0108] According to embodiments of this disclosure, for example, Ti / Au metal evaporation can be performed on the obtained gate cap structure and gate foot structure to obtain a sample of evaporated metal, i.e., the target structure. The thickness of the Ti (titanium) metal can be set to 10 nm, serving as an adhesion layer between the Au (gold) metal and the substrate, and the Au thickness can be set to 300 nm.

[0109] According to embodiments of this disclosure, the selection of the first target metal material is related to the substrate material, specifically the material on which the Y-gate is fabricated. An adhesive layer allows for a stronger adhesion between the Y-gate and the substrate, preventing it from falling off during the adhesive removal process. Without an adhesive layer, the metal Y-gate may fall off the substrate during adhesive removal, and the relatively small bonding area between the gate leads and the substrate makes it prone to detachment during peeling.

[0110] According to embodiments of this disclosure, a target metal material can be filled into the gate cap structure and gate foot structure using a metal evaporation method to obtain a Y-shaped gate.

[0111] According to embodiments of this disclosure, the selection of the first target metal material is related to the material of the substrate.

[0112] According to embodiments of this disclosure, the substrate material is not specific and can be selected from conventional materials commonly used in semiconductor processes, such as silicon, silicon oxide, glass, quartz, diamond, silicon carbide, indium phosphide, gallium nitride, and sapphire. It is also applicable to novel two-dimensional materials such as graphene, carbon nanotubes, fullerenes, or molybdenum disulfide. Similarly, the metal material of the fabricated Y-type gate is not specific and can be selected from metals including gold, silver, copper, titanium, chromium, nickel, molybdenum, platinum, and palladium. The metal material of the Y-type gate can be selected according to the fabrication requirements.

[0113] According to embodiments of this disclosure, selecting a first target metal material for the adhesion layer based on the substrate material can make the Y-gate adhere more firmly to the substrate and prevent it from falling off the substrate during the adhesive removal process.

[0114] Figure 6 A schematic diagram illustrating the metal evaporation process according to an embodiment of the present disclosure is shown.

[0115] like Figure 6 As shown, a Y-shaped grid of a predetermined thickness can be obtained by metal evaporation.

[0116] According to embodiments of this disclosure, Figure 6 All parts can constitute the target structure. During metal evaporation, metal will evaporate onto all surface planes. The metal can be evaporated into the gate cap structure and gate foot structure from the opening region of the second photoresist layer. The thickness of the metal layer on the second photoresist layer is consistent with the thickness of the Y-shaped gate.

[0117] According to embodiments of this disclosure, since metal evaporation is not linear but may be curved, the shape of the upper surface of the Y-shaped gate can be any shape obtained during metal evaporation, such as a straight line, a diagonal line, etc. Figure 6 The groove shape shown is acceptable, as long as the edge portion composed of the gate cap structure and the gate foot structure in the first photoresist layer obtained after development is Y-shaped.

[0118] According to embodiments of this disclosure, by performing the above-described operation S150, the following can be obtained: Figure 6 The target structure in the first photoresist layer, and the Y-shaped gate in the first photoresist layer.

[0119] According to embodiments of this disclosure, the method for fabricating the Y-shaped gate further includes: peeling off the first photoresist layer, the second photoresist layer, and the metal layer on the second photoresist layer obtained by the metal evaporation method in the target structure to obtain the Y-shaped gate.

[0120] According to embodiments of this disclosure, the target structure can be stripped to remove residual electron beam resist and its surface metal. Specifically, the first photoresist layer, the second photoresist layer, and the metal layer on the second photoresist layer obtained by a metal evaporation method are stripped from the target structure to obtain a Y-shaped gate. NMP solution is used for stripping, the stripping temperature can be set to 60°C, and the stripping time can be set to 1 hour. There is no adhesion between the metal on the upper surface of the second photoresist layer and the underlying second photoresist layer, so it can be stripped off.

[0121] According to embodiments of this disclosure, a Y-shaped gate is obtained by peeling off the first photoresist layer, the second photoresist layer, and the metal layer on the second photoresist layer obtained by the metal evaporation method in the target structure.

[0122] Figure 7 A schematic diagram of a Y-shaped gate according to an embodiment of the present disclosure is shown.

[0123] like Figure 7 As shown, this is a Y-shaped gate structure on the substrate obtained through the above operations S110 to S150.

[0124] According to embodiments of this disclosure, the Y-shaped gate can be made of a variety of metallic materials.

[0125] Of course, depending on actual needs, the fabrication method of the Y-type gate disclosed herein may also include other processes and steps, which will not be described in detail here as they are not related to the innovation of this disclosure.

[0126] The embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. It should be noted that implementations not illustrated or described in the drawings or the main text of the specification are forms known to those skilled in the art and are not described in detail. Furthermore, the definitions of the various elements and methods described above are not limited to the specific structures, shapes, or methods mentioned in the embodiments, and those skilled in the art can easily modify or substitute them.

[0127] It should also be noted that the directional terms mentioned in the embodiments, such as "up," "down," "front," "back," "left," and "right," are only for reference to the directions in the accompanying drawings and are not intended to limit the scope of protection of this disclosure. Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or constructions will be omitted where they may cause confusion in understanding this disclosure.

[0128] Furthermore, unless specifically described or required to occur in a specific order, the order of the above steps is not limited to those listed above and can be varied or rearranged according to the desired design. Moreover, the above embodiments can be used in combination with each other or with other embodiments based on design and reliability considerations; that is, technical features from different embodiments can be freely combined to form more embodiments.

[0129] The embodiments of this disclosure have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of this disclosure. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. The scope of this disclosure is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of this disclosure, and all such substitutions and modifications should fall within the scope of this disclosure.

Claims

1. A method for fabricating a Y-type gate, comprising: The process of irradiating a first electron beam photoresist located on the upper surface of a substrate with deep ultraviolet light to obtain a first photoresist layer includes: using the deep ultraviolet light irradiation process to degrade the molecular weight of the first electron beam photoresist to obtain the first photoresist layer, wherein the degree of degradation of the molecular weight of the first electron beam photoresist in the first photoresist layer gradually decreases from top to bottom. A second electron beam photoresist is spin-coated onto the surface of the first photoresist layer to obtain a second photoresist layer, wherein the sensitivity of the second electron beam photoresist is higher than that of the first electron beam photoresist. The process of performing a first exposure and development operation on the first photoresist layer and the second photoresist layer to obtain a Y-shaped gate cap structure includes: exposing the second photoresist layer based on a first exposure size set for the second photoresist layer to obtain a first exposure area of ​​the second photoresist layer; developing the first exposure area of ​​the second photoresist layer using a first developer to obtain the developed structure of the second photoresist layer; and after obtaining the developed structure, developing the first photoresist layer using the first developer based on the degree of degradation of the molecular weight of the first electron beam photoresist in the first photoresist layer to obtain the gate cap structure, wherein the gate cap structure is an inverted trapezoidal structure. Performing a second exposure and development operation on the first photoresist layer after the first exposure and development operation to obtain the gate pin structure of the Y-shaped gate includes: based on the second exposure size set for the first photoresist layer, performing an exposure operation on the first photoresist layer after the first exposure and development operation to obtain a second exposure area of ​​the second photoresist layer; and using a second developer to develop the second exposure area to obtain the gate pin structure. The target metal material is filled into the grid cap structure and the grid foot structure using a metal evaporation method to obtain the Y-shaped grid.

2. The method according to claim 1, wherein, The target metal material includes a first target metal material and a second target metal material. Using a metal evaporation method, the target metal material is filled into the gate cap structure and the gate foot structure to obtain the Y-shaped gate, comprising: An adhesion layer made of the first target metal material is formed on the substrate surface located in the gate pin structure using a metal evaporation method. Using the metal evaporation method, the second target metal material is filled into the gate cap structure and the gate foot structure to obtain a target structure, wherein the target structure includes the Y-shaped gate composed of the first target metal material and the second target metal material.

3. The method according to claim 2, further comprising: The first photoresist layer, the second photoresist layer, and the metal layer on the second photoresist layer obtained by the metal evaporation method in the target structure are peeled off to obtain the Y-shaped gate.

4. The method according to claim 2, wherein, The selection of the first target metal material is related to the material of the substrate.

5. The method according to claim 1, wherein, The thickness of the first photoresist layer is greater than the thickness of the Y-shaped gate, and the first electron beam photoresist is PMMA photoresist.

6. A Y-type gate prepared by the method according to any one of claims 1 to 5.

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