Photoetching process method

Abstract

The invention discloses a photoetching process method, which belongs to the technical field of semiconductors, and comprises the following steps: providing a wafer substrate, and arranging a silicon nitride layer on the wafer substrate; forming a neutralization layer on the silicon nitride layer, wherein the neutralization layer is neutralized with an alkaline substance in the silicon nitride layer; and forming a patterned photoresist layer on the silicon nitride layer or the neutralization layer, and etching the silicon nitride layer. Through the photoetching process method disclosed by the invention, the etching precision of the silicon nitride layer can be improved.

Description

Technical Field

[0001] The invention belongs to the field of semiconductor technology, and in particular relates to a photolithography process method. Background Art

[0002] For chemically amplified photoresists, photoacid plays a vital role in the normal formation of patterns as a catalyst for photochemical reactions. When the film before photolithography contains silicon nitride film, unsaturated nitrogen compounds will be produced during the formation of the silicon nitride film, and the unsaturated nitrogen compounds will react with water in the air to form alkaline substances.

[0003] During the exposure process of the photoresist, the photoacid in the photoresist will react with the alkaline substances in the silicon nitride film, resulting in a decrease in the photoacid concentration in the photoresist. The bottom of the photoresist will produce "footing" defects or bottom photoresist residues due to insufficient development, which is the photoresist poisoning phenomenon. Summary of the invention

[0004] The purpose of the present invention is to provide a photolithography process method which can solve the problem of photoresist poisoning.

[0005] In order to solve the above technical problems, the present invention is achieved through the following technical solutions: The present invention provides a photolithography process method, comprising the following steps: Providing a wafer substrate, wherein a silicon nitride layer is disposed on the wafer substrate; forming a neutralization layer on the silicon nitride layer, wherein the neutralization layer neutralizes the alkaline substance in the silicon nitride layer; and A patterned photoresist layer is formed on the silicon nitride layer or the neutralization layer, and the silicon nitride layer is etched.

[0006] In one embodiment of the present invention, the neutralization layer is a photoresist layer.

[0007] In one embodiment of the present invention, the material of the photoresist layer is G-line photoresist or I-line photoresist.

[0008] In one embodiment of the present invention, when the neutralization layer is a photoresist layer, the photolithography process method comprises the following steps: The photoresist layer is exposed to light to make the photoacid in the photoresist layer react with the alkaline substance.

[0009] In one embodiment of the present invention, when exposing the photoresist, the entire surface of the photoresist layer is subjected to non-patterned exposure.

[0010] In one embodiment of the present invention, after the photoresist layer is exposed to light, the photoresist layer is dissolved by a developer to remove the photoresist layer.

[0011] In one embodiment of the present invention, after removing the photoresist layer, a patterned photoresist layer is formed on the silicon nitride layer, and the silicon nitride layer is etched.

[0012] In one embodiment of the present invention, the exposure wavelength of the photoresist in the patterned photoresist layer is shorter than the exposure wavelength of the photoresist in the neutralization layer.

[0013] In one embodiment of the present invention, the neutralization layer is a silicon oxynitride layer.

[0014] In one embodiment of the present invention, when the neutralization layer is a silicon oxynitride layer, the photolithography process method comprises the following steps: oxidizing the surface of the silicon nitride layer to form a silicon oxynitride layer as the neutralization layer; and The patterned photoresist layer is formed on the silicon oxynitride layer, and the silicon oxynitride layer and the silicon nitride layer are etched.

[0015] In summary, the present invention provides a photolithography process method, which forms a neutralization layer on the silicon nitride layer so that the neutralization layer neutralizes the alkaline substances in the silicon nitride layer, thereby avoiding the phenomenon of photoresist poisoning caused by the reaction of the alkaline substances in the silicon nitride layer with the photoacid in the patterned photoresist layer when forming a patterned photoresist layer, thereby affecting the etching accuracy of the semiconductor film. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0017] Figure 1 This is a flow chart of the photolithography process method in this application.

[0018] Figure 2 This is a flow chart of a photolithography process method when the composite layer is a photoresist layer in an embodiment of the present application.

[0019] Figure 3 FIG. 1 is a schematic diagram of a structure for forming a hard mask layer in an embodiment of the present application.

[0020] Figure 4 It is a schematic structural diagram of forming a photoresist layer as a neutralization layer in one embodiment of the present application.

[0021] Figure 5 Schematic diagram of a structure for etching a semiconductor film using a patterned photoresist layer as a mask in one embodiment of the present application.

[0022] Figure 6This is a flow chart of a photolithography process method when the intermediate layer is a silicon oxynitride layer in another embodiment of the present application.

[0023] Figure 7 FIG. 1 is a schematic diagram of a structure for forming a hard mask layer in another embodiment of the present application.

[0024] Figure 8 This is a schematic structural diagram of forming a silicon oxynitride layer as a neutralization layer in another embodiment of the present application.

[0025] Fig. 9 It is a structural schematic diagram of etching a semiconductor film using a patterned photoresist layer as a mask in another embodiment of the present application.

[0026] Description of labels: 101, substrate; 102, hard mask layer; 1021, pad oxide layer; 1022, silicon nitride layer; 1031, photoresist layer; 1032, silicon oxynitride layer; 104, patterned photoresist layer; 1041, opening. DETAILED DESCRIPTION

[0027] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0028] It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner. Therefore, the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0029] In the present invention, it should be noted that, if the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, if the terms "first" and "second" appear, they are only used for description and distinction purposes, and cannot be understood as indicating or implying relative importance.

[0030] In the photolithography process, a photoresist layer is first formed on the semiconductor film to be photolithographically processed, and then the photoresist layer is exposed to light to transfer the mask pattern on the mask to the photoresist layer. The photoresist layer is then treated with a developer to remove the excess photoresist layer to form a patterned photoresist layer. Finally, the semiconductor film is etched through an etching process, and the patterned photoresist layer is cleaned to complete the photolithography process.

[0031] Please combine Figure 3 and Figure 5 As shown, when the substrate 101 is photolithographically processed, a hard mask layer 102 is first formed on the substrate 101, and a photoresist layer is formed on the hard mask layer 102. Then, through the process of exposure and development, the pattern on the mask is transferred to the photoresist layer to form a patterned photoresist layer 104. Finally, the hard mask layer 102 is etched first, and the pattern on the photoresist layer 1031 is transferred to the hard mask layer 102 to form a patterned hard mask layer. Then, the substrate 101 at the bottom of the hard mask layer 102 is etched to transfer the pattern on the mask to the substrate 101, and the etching of the substrate 101 is completed.

[0032] In addition, in some semiconductor structures, a gate is provided, and it is necessary to form a photolithography on the semiconductor film on the gate to form sidewalls on both sides of the gate. The sidewalls are usually oxide-nitride (ON) layers, oxide-nitride-oxide (ONO) layers, or oxide-nitride-oxide-nitride (ONON) layers. In the process of forming the sidewalls by photolithography, a semiconductor film including oxide and nitride is first formed on the top of the gate, and then a photoresist layer is formed on the semiconductor film. Through the process of exposure and development, the pattern on the mask is transferred to the photoresist layer to form a patterned photoresist layer. Finally, the semiconductor film is etched to retain only the semiconductor film on the sidewalls of the gate to form the gate sidewalls.

[0033] Please combine Figure 3 and Figure 5As shown, when a silicon nitride layer 1022 is provided in the hard mask layer 102, the gate sidewall or other semiconductor film, unsaturated nitrogen compounds will be generated during the formation of the silicon nitride layer 1022. Specifically, when the raw materials for forming silicon nitride, monosilane (SiH4) and ammonia (NH3), react, in addition to forming Si3N4, unsaturated nitrides Si2N and SiN will also be generated. Among them, SiN reacts with water (H2O) to form an alkaline substance OH-SiN3H, and Si2N reacts with water (H2O) and ammonia (NH3) to form SiNH2 and an alkaline substance OH-SiN3. When a photoresist layer is formed on a semiconductor film, the alkaline substance formed in the silicon nitride layer 1022 will react with the photoacid in the photoresist layer, resulting in a decrease in the photoacid concentration. The bottom of the photoresist layer will produce a "footing" defect or bottom photoresist residue due to insufficient development, that is, a photoresist poisoning phenomenon will occur.

[0034] See also Figure 1 As shown, the present application provides a photolithography process method, which can prevent the alkaline substances generated in the hard mask layer from affecting the photoacid concentration in the photoresist, thereby avoiding the photoresist poisoning phenomenon, and further improving the etching accuracy during the etching process. Specifically, the photolithography process method provided by the present invention includes steps S101 to S103.

[0035] Step S101: providing a semiconductor film to be etched, wherein the semiconductor film contains a silicon nitride layer.

[0036] Step S102: forming a neutralization layer on the semiconductor film, and the neutralization layer neutralizes the alkaline substance in the silicon nitride layer.

[0037] Step S103: forming a patterned photoresist layer on the semiconductor film or the neutralization layer, and etching the semiconductor film.

[0038] See also Figures 1 to 9 As shown, in the present application, a neutralizing layer is formed on the semiconductor film to be etched so that the neutralizing layer is neutralized with the alkaline substances in the semiconductor film, thereby avoiding the phenomenon of photoresist poisoning caused by the alkaline substances in the semiconductor film reacting with the photoacid in the patterned photoresist layer 104 when forming the patterned photoresist layer 104, thereby affecting the etching accuracy of the semiconductor film.

[0039] See also Figures 2 to 5 As shown, in one embodiment of the present invention, the neutralizing layer is, for example, a photoresist layer 1031, and the semiconductor film to be etched is a hard mask layer 102. The photolithography process provided by the present invention includes steps S201 to S204.

[0040] Step S201: providing a semiconductor film to be etched, wherein the semiconductor film comprises a stacked pad oxide layer and a silicon nitride layer.

[0041] Step S202: forming a photoresist layer on the semiconductor film as a neutralizing layer, and exposing the photoresist layer.

[0042] Step S203: removing the neutralization layer.

[0043] Step S204: forming a patterned photoresist layer on the semiconductor film, and etching the semiconductor film.

[0044] See also Figure 2 and Figure 3 As shown, in one embodiment of the present invention, the semiconductor film in step S201 is a hard mask layer 102, and the hard mask layer 102 is disposed on a substrate 101. Wherein, the substrate 101 is any applicable semiconductor material, such as a substrate such as sapphire, silicon wafer, silicon carbide (SiC), gallium nitride (GaN), aluminum nitride (AlN), indium nitride (InN) or silicon germanium (GeSi), and also includes a stacked structure composed of these semiconductors, or silicon on insulator, stacked silicon on insulator, stacked silicon germanium on insulator, silicon germanium on insulator, and germanium on insulator, etc., which can be selected according to the manufacturing requirements of the semiconductor device. In this embodiment, the substrate 101 is, for example, a wafer substrate, and the substrate 101 can be an undoped substrate or a doped substrate, and the thickness of the substrate 101 is not specifically limited and is selected according to the manufacturing requirements.

[0045] It should be noted that in other embodiments, the semiconductor film can also be used as a material layer of the sidewall or other material layer, and this application does not impose any restrictions. If the semiconductor film is the material layer of the sidewall, the semiconductor film is disposed on the gate and the substrate.

[0046] See also Figure 3 As shown, in one embodiment of the present invention, in step S201, the hard mask layer 102 formed on the substrate 101 includes a silicon nitride layer 1022. Specifically, in this embodiment, the hard mask layer 102 includes a stacked pad oxide layer 1021 and a silicon nitride layer 1022, that is, the pad oxide layer 1021 is disposed on the substrate 101, and the silicon nitride layer 1022 is disposed on the pad oxide layer 1021.

[0047] See also Figure 3As shown, in one embodiment of the present invention, when forming the hard mask layer 102, a pad oxide layer 1021 is first formed on the substrate 101. The pad oxide layer 1021 is, for example, a material such as dense silicon oxide, and the pad oxide layer 1021 can be formed by any one of the methods such as dry oxygen oxidation, wet oxygen oxidation, or in-situ water vapor growth. The pad oxide layer 1021 is arranged between the subsequently formed silicon nitride layer 1022 and the substrate 101, and can serve as a buffer layer to improve the stress between the substrate 101 and the subsequently formed silicon nitride layer 1022. Among them, the thickness of the pad oxide layer 1021 is, for example, 50Å~70Å, specifically, for example, 60Å or 65Å.

[0048] See also Figure 3 As shown, in one embodiment of the present invention, after forming the pad oxide layer 1021, a silicon nitride layer 1022 is formed on the pad oxide layer 1021. In this embodiment, the silicon nitride layer can be formed using a method such as low pressure chemical vapor deposition (LPCVD). In the subsequent shallow trench isolation structure formation process, the silicon nitride layer 1022 is used as a mask to protect the substrate 101 from damage when etching the substrate 101. The thickness of the silicon nitride layer 1022 is, for example, 200Å~300Å, specifically, for example, 250Å.

[0049] See also Figure 3 As shown, it should be noted that the present application does not limit the specific material of each semiconductor layer in the hard mask layer 102, and the pad oxide layer 1021 and the silicon nitride layer 1022 may also be any other suitable hard mask material.

[0050] See also Figure 3 to Figure 4 As shown, in one embodiment of the present invention, in step S202, after forming a semiconductor film containing a silicon nitride layer 1022, a neutralization layer is formed on the semiconductor film. The neutralization layer neutralizes the alkaline substances in the silicon nitride layer, thereby preventing the alkaline substances in the silicon nitride layer 1022 from affecting the photoresist concentration.

[0051] See also Figure 3 to Figure 4 As shown, in one embodiment of the present invention, the neutralization layer in step S202 is a photoresist layer 1031. After the hard mask layer 102 is formed, a photoresist layer 1031 is formed on the hard mask layer 102 by spin coating as a neutralization layer. Specifically, the photoresist solution can be poured into a coating machine first, and then the substrate 101 with the hard mask layer 102 is fixed on a rotating platform. When the rotating platform starts to rotate, the coating machine will evenly coat the photoresist on the surface of the hard mask layer 102, and then form a photoresist layer 1031 on the hard mask layer 102 as a neutralization layer.

[0052] See also Figure 3 to Figure 4 As shown, in one embodiment of the present invention, in step S202, after the photoresist layer 1031 is formed, the photoresist layer 1031 is exposed. Specifically, the substrate 101 with the photoresist layer 1031 and the hard mask layer 102 is placed in a photolithography machine, and light is irradiated on the photoresist layer 1031 by controlling the intensity and time of the light source. During the exposure process of the photoresist layer 1031, the entire surface of the photoresist layer 1031 is exposed without patterning, that is, no photomask is required. At this time, the entire surface of the photoresist layer 1031 will be irradiated by light of a specific wavelength, and under the action of photons, the photosensitive compound decomposes to produce photoacid. At this time, the photoacid of the photoresist layer 1031 reacts with the alkaline substance in the hard mask layer 102, and then neutralizes the alkaline substance in the hard mask layer 102, completing the neutralization of the alkaline substance in the neutralization layer and the hard mask layer 102.

[0053] See also Figure 2 and Figure 4 As shown, in one embodiment of the present invention, in step S203, when the neutralization layer is a photoresist layer 1031, after the neutralization of the neutralization layer and the alkaline substance in the semiconductor film is completed, the neutralization layer is removed. Specifically, after the photoresist layer 1031 is exposed, the photoresist layer 1031 is treated with a developer to dissolve the exposed area of ​​the photoresist layer 1031, and then the photoresist layer 1031 is removed.

[0054] See also Figure 4 As shown, in one embodiment of the present invention, the neutralization layer is a photoresist layer 1031, and the material of the photoresist layer 1031 is a G-line photoresist or an I-line photoresist. At this time, the exposure wavelength of the photoresist is relatively long, and the processing resolution is low. However, since the photoresist layer 1031 is used as a neutralization layer, the function of the photoresist layer 1031 is not to transfer the pattern, but to react the photoacid in the photoresist layer 1031 with the alkaline substance in the hard mask layer 102, it is not necessary to use a high-resolution photoresist, and the economic benefits can be improved while neutralizing the alkaline substance.

[0055] See also Figure 4 As shown, the present application does not limit the thickness and exposure time of the photoresist layer 1031 , and is specifically based on the ability to neutralize the alkaline substances in the hard mask layer 102 .

[0056] See also Figures 2 to 5As shown, in one embodiment of the present invention, after the alkaline substance in the semiconductor film is neutralized by using the neutralizing layer, step S204 is performed to form a patterned photoresist layer 104 on the semiconductor film, and the semiconductor film is etched. Specifically, a photoresist layer can be formed on the hard mask layer 102 by spin coating, and the photoresist layer is exposed by using a photomask, and then a part of the photoresist is removed by a development process to form a patterned photoresist layer 104. After the patterned photoresist layer 104 is formed, the hard mask layer 102 is first etched using the patterned photoresist layer 104 as a mask, and the photoresist pattern in the patterned photoresist layer 104 is transferred to the hard mask layer 102. That is, an opening 1041 is formed in the hard mask layer 102, and the opening 1041 exposes a part of the substrate 101. In the process of etching the hard mask layer 102, the etching gas is a mixed gas including fluorine-containing gas, chlorine gas, oxygen, helium, etc., and an inert gas (such as hydrogen Ar, neon Ne), etc. After the photoresist pattern on the patterned photoresist layer 104 is transferred onto the hard mask layer 102 , the patterned photoresist layer 104 is removed to complete the etching of the semiconductor film.

[0057] See also Figures 2 to 5 As shown, in some embodiments, when the semiconductor film is the hard mask layer 102, after etching the hard mask layer 102, the substrate 101 is etched using the hard mask layer 102 as a mask by adopting reactive ion etching or plasma etching.

[0058] See also Figure 5 As shown, in one embodiment of the present invention, in step S204, the material of the patterned photoresist layer 104 can be KrF photoresist, ArF photoresist or EUV photoresist, etc. At this time, the exposure wavelength of the photoresist is short, the processing resolution is high, and the etching accuracy can be improved. That is, the exposure wavelength of the photoresist in the patterned photoresist layer 104 is shorter than the exposure wavelength of the photoresist in the neutralization layer.

[0059] See also Figures 6 to 9 As shown, in another embodiment of the present invention, the neutralizing layer is, for example, a silicon oxynitride layer 1032. And the semiconductor film to be etched includes a hard mask layer 102. Then the photolithography process provided by the present invention includes steps S301 to S303.

[0060] Step S301: providing a semiconductor film to be etched, wherein the semiconductor film comprises a stacked pad oxide layer and a silicon nitride layer.

[0061] Step S302: oxidize the surface of the silicon nitride layer to form a silicon oxynitride layer as a neutralizing layer.

[0062] Step S303: forming a patterned photoresist layer on the neutralization layer, and etching the neutralization layer and the semiconductor film.

[0063] See also Figure 7As shown, in another embodiment of the present invention, the semiconductor film in step S301 is a hard mask layer 102, and the hard mask layer 102 is disposed on a substrate 101. Wherein, the substrate 101 is any applicable semiconductor material, such as a substrate such as sapphire, silicon wafer, silicon carbide (SiC), gallium nitride (GaN), aluminum nitride (AlN), indium nitride (InN) or silicon germanium (GeSi), and also includes a stacked structure composed of these semiconductors, or silicon on insulator, stacked silicon on insulator, stacked silicon germanium on insulator, silicon germanium on insulator, and germanium on insulator, etc., which can be selected according to the manufacturing requirements of the semiconductor device. In this embodiment, the substrate 101 is, for example, a wafer substrate, and the substrate 101 can be an undoped substrate or a doped substrate, and the thickness of the substrate 101 is not specifically limited, and is selected according to the manufacturing requirements. It should be noted that in other embodiments, the semiconductor film can also be used as a material layer or other material layer of the sidewall, and this application does not impose many restrictions.

[0064] It should be noted that in other embodiments, the semiconductor film can also be used as a material layer of the sidewall or other material layer, and this application does not impose any restrictions. If the semiconductor film is the material layer of the sidewall, the semiconductor film is disposed on the gate and the substrate.

[0065] See also Figure 7 As shown, in another embodiment of the present invention, in step S301, the hard mask layer 102 formed on the substrate 101 includes a silicon nitride layer 1022. Specifically, in this embodiment, the hard mask layer 102 includes a stacked pad oxide layer 1021 and a silicon nitride layer 1022, that is, the pad oxide layer 1021 is disposed on the substrate 101, and the silicon nitride layer 1022 is disposed on the pad oxide layer 1021.

[0066] See also Figure 7 As shown, in another embodiment of the present invention, when forming the hard mask layer 102, a pad oxide layer 1021 is first formed on the substrate 101. The pad oxide layer 1021 is, for example, a material such as dense silicon oxide, and the pad oxide layer 1021 can be formed by any one of the methods such as dry oxygen oxidation, wet oxygen oxidation, or in-situ water vapor growth. The pad oxide layer 1021 is arranged between the subsequently formed silicon nitride layer 1022 and the substrate 101, and can serve as a buffer layer to improve the stress between the substrate 101 and the subsequently formed silicon nitride layer 1022. Among them, the thickness of the pad oxide layer 1021 is, for example, 50Å~70Å, specifically, for example, 60Å or 65Å.

[0067] See also Figure 7As shown, in another embodiment of the present invention, after forming the pad oxide layer 1021, a silicon nitride layer 1022 is formed on the pad oxide layer 1021. In this embodiment, the silicon nitride layer can be formed using a method such as low pressure chemical vapor deposition (LPCVD). In the subsequent shallow trench isolation structure formation process, the silicon nitride layer 1022 is used as a mask to protect the substrate 101 from damage when etching the substrate 101. The thickness of the silicon nitride layer 1022 is, for example, 200Å~300Å, specifically, for example, 250Å.

[0068] See also Figure 7 As shown, it should be noted that the present application does not limit the specific material of each semiconductor layer in the hard mask layer 102, and the pad oxide layer 1021 and the silicon nitride layer 1022 may also be any other suitable hard mask material.

[0069] See also Figures 6 to 9 As shown, in another embodiment of the present invention, in step S302, after forming a semiconductor film containing a silicon nitride layer 1022, a neutralization layer is formed on the semiconductor film. The neutralization layer neutralizes the alkaline substances in the silicon nitride layer, thereby preventing the alkaline substances in the silicon nitride layer 1022 from affecting the photoresist concentration.

[0070] See also Figures 7 and 8 As shown, in another embodiment of the present invention, the neutralization layer in step S302 is a silicon oxynitride layer 1032. That is, after the hard mask layer 102 is formed, the surface of the silicon nitride layer 1022 is oxidized to form a silicon oxynitride layer 1032 as a neutralization layer. Specifically, the substrate 101 provided with the hard mask layer 102 can be placed in a high-temperature reaction chamber, and oxygen or gaseous water can be introduced into the reaction chamber so that the nitrogen atoms on the surface of the silicon nitride layer 1022 are combined with oxygen atoms to form nitrogen oxides, and further, silicon atoms are combined with the remaining nitrogen atoms to form silicon oxynitride. At this time, the unsaturated nitrogen compounds in the silicon nitride layer 1022 are combined with the oxygen atoms and the silicon atoms to form the silicon oxynitride layer 1032, which can eliminate the alkaline substances formed in the silicon nitride layer 1022.

[0071] See also Figure 8 and Fig. 9As shown, in another embodiment of the invention, since the neutralization layer formed is a silicon oxynitride layer 1032 that does not contain alkaline substances or acidic substances, it will not affect the formation of the patterned photoresist layer 104, nor will it affect the etching accuracy. To a certain extent, if the silicon nitride layer 1022 still contains alkaline substances, the silicon oxynitride layer 1032 can also isolate the alkaline substances in the silicon nitride layer 1022 from the subsequently formed patterned photoresist layer 104. Therefore, in this embodiment, after the silicon oxynitride layer 1032 is formed as a neutralization layer, after the neutralization of the alkaline substances in the semiconductor film is completed, the silicon oxynitride layer 1032 does not need to be removed, and the silicon oxynitride layer 1032 is still retained on the hard mask layer 102.

[0072] See also Fig. 9 As shown, in another embodiment of the present invention, after forming a silicon oxynitride layer 1032 as a neutralization layer on the semiconductor film, step S303 is performed to form a patterned photoresist layer 104 on the neutralization layer, and the neutralization layer and the semiconductor film are etched. In step S303, a photoresist layer can be first formed on the hard mask layer 102 by spin coating, and the photoresist layer is exposed using a mask, and then a portion of the photoresist is removed by a development process to form a patterned photoresist layer 104. After the patterned photoresist layer 104 is formed, the silicon oxynitride layer 1032 and the hard mask layer 102 are first etched using the patterned photoresist layer 104 as a mask, and the photoresist pattern in the patterned photoresist layer 104 is transferred to the silicon oxynitride layer 1032 and the hard mask layer 102. That is, an opening 1041 is formed in the hard mask layer 102, and the opening 1041 exposes a portion of the substrate 101. In the process of etching the silicon oxynitride layer 1032 and the hard mask layer 102, the etching gas is a mixed gas including fluorine-containing gas, chlorine gas, oxygen, helium, etc., and an inert gas (such as hydrogen Ar, neon Ne), etc. After the photoresist pattern on the patterned photoresist layer 104 is transferred to the silicon oxynitride layer 1032 and the hard mask layer 102, the patterned photoresist layer 104 is removed to complete the etching of the semiconductor film.

[0073] See also Fig. 9 As shown, in some embodiments, when the semiconductor film is a hard mask layer 102, after etching the hard mask layer 102, the substrate 101 is further etched by reactive ion etching or plasma etching using the hard mask layer 102 as a mask.

[0074] See also Fig. 9 As shown, in one embodiment of the present invention, in step S303, the material of the patterned photoresist layer 104 can be KrF photoresist, ArF photoresist or EUV photoresist, etc. At this time, the photoresist exposure wavelength is short, the processing resolution is high, and the etching accuracy can be improved.

[0075] In summary, the present invention provides a photolithography process method, which includes: providing a wafer substrate, and a silicon nitride layer is arranged on the wafer substrate; forming a neutralization layer on the silicon nitride layer, and the neutralization layer neutralizes the alkaline substance in the silicon nitride layer; and forming a patterned photoresist layer on the silicon nitride layer or the neutralization layer, and photolithography the silicon nitride layer. In the present application, by forming a neutralization layer on the silicon nitride layer to be etched, the neutralization layer is neutralized with the alkaline substance in the silicon nitride layer, so as to avoid the alkaline substance in the silicon nitride layer reacting with the photoacid in the patterned photoresist layer when forming the patterned photoresist layer, resulting in the phenomenon of photoresist poisoning, which affects the etching accuracy of the silicon nitride layer.

[0076] The embodiments of the present invention disclosed above are only used to help illustrate the present invention. The embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A photolithography process, characterized in that: The following steps are involved: Providing a wafer substrate, wherein a silicon nitride layer is disposed on the wafer substrate; forming a neutralization layer on the silicon nitride layer, wherein the neutralization layer neutralizes the alkaline substance in the silicon nitride layer; as well as A patterned photoresist layer is formed on the silicon nitride layer or the neutralization layer, and the silicon nitride layer is etched.

2. The photolithography process according to claim 1, characterized in that: The neutralization layer is a photoresist layer.

3. The photolithography process according to claim 2, characterized in that: The material of the photoresist layer is G-line photoresist or I-line photoresist.

4. The photolithography process according to claim 2, characterized in that: When the neutralization layer is a photoresist layer, the photolithography process method comprises the following steps: The photoresist layer is exposed to light to make the photoacid in the photoresist layer react with the alkaline substance.

5. The photolithography method according to claim 4, characterized in that: When the photoresist is exposed, the entire surface of the photoresist layer is exposed without patterning.

6. The photolithography method according to claim 4, characterized in that: After the photoresist layer is exposed, the photoresist layer is dissolved by a developer to remove the photoresist layer.

7. The photolithography process according to claim 6, characterized in that: After removing the photoresist layer, a patterned photoresist layer is formed on the silicon nitride layer, and the silicon nitride layer is etched.

8. The photolithography process according to claim 6, characterized in that: The exposure wavelength of the photoresist in the patterned photoresist layer is shorter than the exposure wavelength of the photoresist in the neutralization layer.

9. The photolithography process according to claim 1, characterized in that: The neutralization layer is a silicon oxynitride layer.

10. The photolithography method according to claim 9, characterized in that: When the neutralization layer is a silicon oxynitride layer, the photolithography process method comprises the following steps: oxidizing the surface of the silicon nitride layer to form a silicon oxynitride layer as the neutralization layer; and The patterned photoresist layer is formed on the silicon oxynitride layer, and the silicon oxynitride layer and the silicon nitride layer are etched.

Images