Photoresist removing method and reworking method of photoetching process

Abstract

The invention relates to a photoresist removing method and a reworking method of a photoetching process, and the reworking method comprises the following steps: providing a wafer, the surface of which is provided with a first negative photoresist layer; carrying out chemical reaction treatment on the first negative photoresist layer by adopting a tetramethylammonium hydroxide solution; carrying out cleaning treatment by adopting an organic solvent to remove residues after chemical reaction treatment; and baking the wafer. According to the method, only the first negative photoresist layer is removed, so that the electrical performance of the device structure is prevented from being influenced by damage to the formed device structure, and meanwhile, the time and material cost can be effectively reduced. The organic solvent is adopted for cleaning treatment to remove residues, so that defects can be prevented from being formed during exposure and development after the second negative photoresist is spin-coated. The wafer is baked, the silicon-containing photoresist anti-reflection layer can be repaired through high-temperature baking, and the pattern size deviation before and after reworking caused by exposure and development after spin coating of the second negative photoresist layer can be reduced.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing technologies, and particularly to a method for removing photoresist and a method for reworking a lithography process. Background Art

[0002] In semiconductor device manufacturing technologies, a photomask pattern on a photomask is usually transferred to a photoresist layer on the surface of a wafer by using a lithography process. Generally, the basic processes of lithography include steps such as spin coating, exposure, and development. The purpose of spin coating is to establish a thin, uniform, and defect-free photomask layer on the surface of the wafer; the purpose of exposure is to transfer the photomask pattern to the photoresist layer by using an exposure light source; development is to pattern the photoresist layer and remove the exposed or unexposed areas of the photoresist layer, thereby forming a patterned photoresist layer on the surface of the wafer. Then, the wafer is etched under the masking of the patterned photoresist layer, and the photomask pattern is transferred to the wafer, thereby forming a circuit pattern in the wafer.

[0003] Usually, after the development process is completed, an after-development inspection (ADI) is performed on the formed photoresist layer. In the process of advanced process nodes, continuously shrinking process windows and overlay errors often result in defects being found in the post-development inspection step, which will in turn affect the reliability of the device structure. In this case, rework is required. The general procedure for rework is to first remove the formed photoresist, and then repeat the lithography process steps to finally form a photolithographic pattern that meets the product requirements.

[0004] However, there are still many problems in the process of removing photoresist in the prior art. Summary of the Invention

[0005] The technical problem solved by the present invention is to provide a method for removing photoresist and a method for reworking a lithography process, which reduce the impact on the electrical performance of the device structure, reduce time costs and material costs, reduce defects during re-exposure and development, and reduce the pattern size deviation before and after rework.

[0006] To solve the above problems, the present invention provides a method for removing photoresist, including: providing a wafer having a negative photoresist layer on its surface; performing a chemical reaction treatment on the negative photoresist layer with a tetramethylammonium hydroxide solution; performing a cleaning treatment with an organic solvent to remove the residues after the chemical reaction treatment; and baking the wafer after the cleaning treatment.

[0007] Optionally, the organic solvent includes: a photoresist thinner or propylene glycol monomethyl ether acetate.

[0008] Optionally, the photoresist diluent includes one or more of propylene glycol methyl ether, propylene glycol methyl acetate, OK73 diluent, cyclohexanone, and ν-butyrolactone.

[0009] Optionally, the process parameters of the baking treatment include: a baking temperature of 150 °C to 220 °C; a baking time of 15 seconds to 500 seconds.

[0010] Optionally, the wafer surface further has: a spin-coated organic carbon layer, and a silicon-containing photoresist anti-reflection layer located on the spin-coated organic carbon layer.

[0011] Optionally, the negative photoresist layer is spin-coated on the silicon-containing photoresist anti-reflection layer.

[0012] Correspondingly, the technical solution of the present invention also provides a rework method for a lithography process, including: providing a wafer, the surface of the wafer having a first negative photoresist layer; performing a chemical reaction treatment on the first negative photoresist layer with a tetramethylammonium hydroxide solution; performing a cleaning treatment with an organic solvent to remove the residue after the chemical reaction treatment; after the cleaning treatment, performing a baking treatment on the wafer; after the baking treatment, spin-coating a second negative photoresist layer on the surface of the wafer; performing an exposure and development treatment on the second negative photoresist layer.

[0013] Optionally, the organic solvent includes: a photoresist diluent or propylene glycol methyl ether acetate.

[0014] Optionally, the photoresist diluent includes one or more of propylene glycol methyl ether, propylene glycol methyl acetate, OK73 diluent, cyclohexanone, and ν-butyrolactone.

[0015] Optionally, the process parameters of the baking treatment include: a baking temperature of 150 °C to 220 °C; a baking time of 15 seconds to 500 seconds.

[0016] Optionally, the wafer surface further has: a spin-coated organic carbon layer, and a silicon-containing photoresist anti-reflection layer located on the spin-coated organic carbon layer.

[0017] Optionally, the first negative photoresist layer is spin-coated on the silicon-containing photoresist anti-reflection layer.

[0018] Optionally, the second negative photoresist layer is spin-coated on the silicon-containing photoresist anti-reflection layer.

[0019] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0020] In the photoresist removal method of the technical solution of the present invention, by only removing the negative photoresist layer, damage to the formed device structure is avoided, thereby affecting the electrical performance of the device structure. At the same time, the time cost and material cost can be effectively reduced. By using an organic solvent for cleaning to remove the residue after the chemical reaction treatment, defects formed during exposure and development can be avoided after re-spinning the negative photoresist. After the cleaning treatment, by baking the wafer, the silicon-containing photoresist antireflection layer can be repaired by the high-temperature baking treatment, and the pattern size deviation before and after rework caused during exposure and development after re-spinning the negative photoresist layer can be reduced.

[0021] In the rework method of the lithography process of the technical solution of the present invention, by only removing the first negative photoresist layer, damage to the formed device structure is avoided, thereby affecting the electrical performance of the device structure. At the same time, the time cost and material cost can be effectively reduced. By using an organic solvent for cleaning to remove the residue after the chemical reaction treatment, defects formed during exposure and development can be avoided after re-spinning the second negative photoresist layer. After the cleaning treatment, by baking the wafer, the silicon-containing photoresist antireflection layer can be repaired by the high-temperature baking treatment, and the pattern size deviation before and after rework caused during exposure and development after re-spinning the second negative photoresist layer can be reduced. Description of the Drawings

[0022] Figure 1 and Figure 2 are schematic structural diagrams of the steps of a photoresist removal method;

[0023] Figure 3 are schematic structural diagrams of the steps of another photoresist removal method;

[0024] Figure 4 is an electron microscope image of defects formed after the negative photoresist layer is developed and inspected;

[0025] Figures 5 to 8 are schematic structural diagrams of the steps of the photoresist removal method of the embodiment of the present invention;

[0026] Figures 9 to 13 are schematic structural diagrams of the steps of the rework method of the lithography process of the embodiment of the present invention. Detailed Embodiments

[0027] As described in the background art, there are still many problems in the process of removing photoresist in the prior art. The following will be specifically described with reference to the drawings.

[0028] Figure 1 and Figure 2 are schematic structural diagrams of the steps of a photoresist removal method.

[0029] Please refer to Figure 1 , a wafer 100 is provided, and a spin-on organic carbon layer 101 is formed on the surface of the wafer 100, a silicon-containing photoresist anti-reflection layer 102 is formed on the spin-on organic carbon layer 101, and a negative photoresist layer 103 is formed on the silicon-containing photoresist anti-reflection layer 102.

[0030] Please refer to Figure 2 , a photoresist thinner is used to remove the negative photoresist layer 103, the silicon-containing photoresist anti-reflection layer 102, and the spin-on organic carbon layer 101.

[0031] The negative photoresist layer 103, the silicon-containing photoresist anti-reflection layer 102, and the spin-on organic carbon layer 101 are so-called tri-layer photoresist materials (tri-laye). Among them, the silicon content in the silicon-containing photoresist anti-reflection layer 102 (SiARC) can reach 40%, and the carbon content in the spin-on organic carbon layer 101 (Spin On Carbon, SOC) reaches 80% - 90%. This three-layer structure can not only effectively reduce reflection during exposure but also improve selectivity during etching, so it is widely used in the lithography process.

[0032] However, removing the negative photoresist layer 103, the silicon-containing photoresist anti-reflection layer 102, and the spin-on organic carbon layer 101 together by the photoresist thinner (Reduced Resist Consumption, RRC) will damage the formed device structure. For example, during the process of forming contact holes and metal layers using the dual damascene process, when using the photoresist thinner to remove the negative photoresist layer 103, the silicon-containing photoresist anti-reflection layer 102, and the spin-on organic carbon layer 101 together, it will cause damage to titanium aluminide (TiAl) on the metal gate (Metal Gate, MG) (as shown in part A of Figure 2 ), and damage to the sidewall of the metal layer opening (as shown in part B of Figure 2 ). Moreover, the time cost and material cost of using the photoresist thinner to remove the negative photoresist layer 103, the silicon-containing photoresist anti-reflection layer 102, and the spin-on organic carbon layer 101 together will also increase.

[0033] To solve the above problems, another photoresist removal method has been adopted in the prior art. The specific process will be described in detail below.

[0034] Figure 3 is a schematic structural diagram of each step of another photoresist removal method; Figure 4 is a scanning electron microscope image of the negative photoresist layer after development to check for defects.

[0035] Please continue to refer to Figure 1and in combination with reference Figure 3 , the negative photoresist layer 103 is removed.

[0036] To avoid damaging the electrical performance of the device structure and to reduce time and material costs, there are currently two ways to remove the negative photoresist layer 103 by only removing the negative photoresist layer 103: One is to rinse and remove the negative photoresist layer 103 with a photoresist thinner. However, since the negative photoresist layer 103 has a low solubility in the photoresist thinner, after spin-coating the negative photoresist layer again, defects (such as Figure 4 shown) will be formed during the After Development Inspection (ADI) during exposure; The other is to remove the negative photoresist layer 103 by combining a photoresist thinner and a tetramethylammonium hydroxide (TAMH) solution. However, since the silicon-containing photoresist antireflection layer 102 is a porous material, during the chemical reaction process, due to the entry of small molecules, the thickness of the silicon-containing photoresist antireflection layer 102 will increase. Due to the change in the surface of the silicon-containing photoresist antireflection layer 102, after spin-coating the negative photoresist layer again, during the development inspection process after exposure, the Critical Dimension (CD) bias between the patterns before and after rework will increase.

[0037] On this basis, the present invention provides a method for removing photoresist and a method for reworking a lithography process. By only removing the negative photoresist layer, damage to the formed device structure is avoided, thereby affecting the electrical performance of the device structure. At the same time, time costs and material costs can be effectively reduced. By using an organic solvent for cleaning to remove the residues after the chemical reaction treatment, defects formed during exposure and development can be avoided after spin-coating the negative photoresist again. After the cleaning treatment, by baking the wafer, the silicon-containing photoresist antireflection layer can be repaired by the high-temperature baking treatment, and the CD bias between the patterns before and after rework caused during exposure and development after spin-coating the negative photoresist layer again can be reduced.

[0038] To make the above objects, features, and advantages of the present invention more obvious and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0039] Figures 5 to 8 are the schematic structural diagrams of the steps of the photoresist removal method according to the embodiments of the present invention.

[0040] Please refer to Figure 5 , a wafer 200 is provided, and a negative photoresist layer 203 is disposed on the surface of the wafer 200.

[0041] It should be noted that part of the semiconductor manufacturing process has been carried out on the wafer 200, and a device structure has been formed within the wafer 200.

[0042] In this embodiment, the surface of the wafer 200 further has: a spin-on organic carbon layer 201, and a silicon-containing photoresist anti-reflection layer 202 located on the spin-on organic carbon layer 201.

[0043] In this embodiment, the negative photoresist layer 203 is spin-coated on the silicon-containing photoresist anti-reflection layer 202.

[0044] The negative photoresist layer 203, the silicon-containing photoresist anti-reflection layer 202, and the spin-on organic carbon layer 201 are the so-called three-layer photolithography materials (tri-laye). Among them, the silicon content in the silicon-containing photoresist anti-reflection layer 202 (SiARC) can reach 40%, and the carbon content in the spin-on carbon layer (Spin On Carbon, SOC) reaches 80% - 90%. This three-layer structure can not only effectively reduce reflection during exposure but also improve the selectivity during etching.

[0045] Please refer to Figure 6 , and a chemical reaction treatment 204 is carried out on the negative photoresist layer 203 using a tetramethylammonium hydroxide solution.

[0046] It should be noted that the negative photoresist layer 203 is a light-sensitive mixed liquid composed of three main components: a photosensitive resin, a sensitizer (see spectral sensitizing dyes), and a solvent. Among them, after the photosensitive resin is irradiated with light, a photocuring reaction can quickly occur in the exposed area, causing obvious changes in the physical properties of this material, especially solubility, affinity, etc. After appropriate solvent treatment, the soluble part is dissolved to obtain the required image. And the tetramethylammonium hydroxide solution (Tetramethylammonium hydroxide, TAMH) can only chemically react with the negative photoresist layer 203 and cannot react with the positive photoresist layer.

[0047] Please refer to Figure 7 , and a cleaning treatment 205 is carried out using an organic solvent to remove the residue after the chemical reaction treatment 204.

[0048] The organic solvent includes: a photoresist thinner or propylene glycol monomethyl ether acetate.

[0049] In this embodiment, the organic solvent used is a photoresist thinner.

[0050] The photoresist thinner includes: one or more of propylene glycol monomethyl ether, propylene glycol monomethyl acetate, OK73 thinner, cyclohexanone, and ν-butyrolactone.

[0051] Please refer toFigure 8 After the cleaning process 205, a baking process 206 is performed on the wafer 200.

[0052] By only removing the negative photoresist layer 203, damage to the formed device structure is avoided, thereby affecting the electrical performance of the device structure. At the same time, the time cost and material cost can be effectively reduced. By using an organic solvent for the cleaning process 205 to remove the residues after the chemical reaction process 204, defects formed during exposure and development can be avoided when the negative photoresist is spin-coated again. By performing the baking process 206 on the wafer 200 after the cleaning process 205, the silicon-containing photoresist antireflection layer 202 can be repaired by the high-temperature baking process 206, and the pattern size deviation before and after rework caused during exposure and development can be reduced when the negative photoresist layer 203 is spin-coated again.

[0053] In this embodiment, the process parameters of the baking process 206 include: a baking temperature of 150 °C to 220 °C; a baking time of 15 seconds to 500 seconds.

[0054] Figures 9 to 13 It is a schematic diagram of the structures of the steps of the rework method of the lithography process according to the embodiment of the present invention.

[0055] Correspondingly, an embodiment of the present invention also provides a rework method for a lithography process. For the specific process, please refer to Figures 9 to 13 as shown.

[0056] Please refer to Figure 9 , a wafer 300 is provided, and a first negative photoresist layer 303 is formed on the surface of the wafer 300.

[0057] In this embodiment, the surface of the wafer 300 further has: a spin-coated organic carbon layer 301, and a silicon-containing photoresist antireflection layer 302 located on the spin-coated organic carbon layer 301.

[0058] In this embodiment, the first negative photoresist layer 303 is spin-coated on the silicon-containing photoresist antireflection layer 302.

[0059] The first negative photoresist layer 303, the silicon-containing photoresist antireflection layer 302, and the spin-coated organic carbon layer 301 are the so-called three-layer lithography materials (tri-laye). Among them, the silicon content in the silicon-containing photoresist antireflection layer 302 (SiARC) can reach 40%, and the carbon content in the spin-on carbon layer (Spin On Carbon, SOC) reaches 80% to 90%. This three-layer structure can effectively reduce reflection during exposure and improve selectivity during etching.

[0060] Please refer to Figure 10, a chemical reaction treatment 304 is performed using a tetramethylammonium hydroxide solution and the first negative photoresist layer 303.

[0061] It should be noted that the first negative photoresist layer 303 is a photosensitive mixed liquid composed of three main components: a photosensitive resin, a sensitizer (see spectral sensitizing dyes), and a solvent. After the photosensitive resin is irradiated with light, a photocuring reaction can quickly occur in the exposed area, causing significant changes in the physical properties of this material, especially solubility, affinity, etc. After appropriate solvent treatment, the soluble part is dissolved to obtain the required image. And the tetramethylammonium hydroxide solution (Tetramethylammonium hydroxide, TAMH) can only chemically react with the first negative photoresist layer 303 and cannot react with the positive photoresist layer.

[0062] Please refer to Figure 11 , an organic solvent is used for cleaning treatment 305 to remove the residue after the chemical reaction treatment 304.

[0063] The organic solvent includes: a photoresist thinner or propylene glycol monomethyl ether acetate.

[0064] In this embodiment, the organic solvent uses a photoresist thinner.

[0065] The photoresist thinner includes: one or more of propylene glycol monomethyl ether, propylene glycol methyl acetate, OK73 thinner, cyclohexanone, and ν-butyrolactone.

[0066] Please refer to Figure 12 , after the cleaning treatment 305, a baking treatment 306 is performed on the wafer 300.

[0067] In this embodiment, the process parameters of the baking treatment 306 include: a baking temperature of 150 °C to 220 °C; a baking time of 15 seconds to 500 seconds.

[0068] Please refer to Figure 13 , after the baking treatment 306, a second negative photoresist layer 307 is spin-coated on the surface of the wafer 300; an exposure and development treatment is performed on the second negative photoresist layer 307.

[0069] By removing only the first negative photoresist layer 303, damage to the formed device structure is avoided, thereby affecting the electrical performance of the device structure. At the same time, the time cost and material cost can be effectively reduced. By using an organic solvent for cleaning treatment 305 to remove the residue after the chemical reaction treatment 304, defects formed during exposure and development can be avoided after the second negative photoresist layer 307 is spin-coated again. By baking the wafer 300 after the cleaning treatment 305, the silicon-containing photoresist antireflection layer 302 can be repaired by the high-temperature baking treatment 306, and the pattern size deviation before and after rework caused during exposure and development after the second negative photoresist layer 307 is spin-coated again can be reduced.

[0070] In this embodiment, the second negative photoresist layer 307 is spin-coated on the silicon-containing photoresist antireflection layer 302.

[0071] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be subject to the scope defined by the claims.

Claims

1. A photoresist removal method, characterized in that, Comprising: Providing a wafer having a negative photoresist layer on its surface; Performing a chemical reaction treatment on the negative photoresist layer with a tetramethylammonium hydroxide solution; Performing a cleaning treatment with an organic solvent to remove the residues after the chemical reaction treatment; After the cleaning treatment, baking the wafer.

2. The photoresist removal method according to claim 1, wherein, The organic solvent includes: a photoresist thinner or propylene glycol monomethyl ether acetate.

3. The photoresist removal method according to claim 2, wherein The photoresist thinner includes: one or more of propylene glycol monomethyl ether, propylene glycol monoacetate, OK73 thinner, cyclohexanone, and ν-butyrolactone.

4. The photoresist removal method according to claim 1, wherein, The process parameters of the baking treatment include: a baking temperature of 150 °C to 220 °C; a baking time of 15 seconds to 500 seconds.

5. The photoresist removal method according to claim 1, wherein The wafer surface further has: a spin-coated organic carbon layer, and a silicon-containing photoresist antireflection layer located on the spin-coated organic carbon layer.

6. The photoresist removal method according to claim 5, characterized in that, The negative photoresist layer is spin-coated on the silicon-containing photoresist antireflection layer.

7. A rework method for a lithography process, characterized in that, Comprising: Providing a wafer having a first negative photoresist layer on its surface; Performing a chemical reaction treatment on the first negative photoresist layer with a tetramethylammonium hydroxide solution; Performing a cleaning treatment with an organic solvent to remove the residues after the chemical reaction treatment; After the cleaning treatment, baking the wafer; After the baking treatment, spin-coating a second negative photoresist layer on the wafer surface; Performing an exposure and development treatment on the second negative photoresist layer.

8. The rework method of the lithography process according to claim 7, characterized in that, The organic solvent includes: a photoresist thinner or propylene glycol monomethyl ether acetate.

9. The rework method of the lithography process according to claim 8, wherein, The photoresist thinner includes: one or more of propylene glycol monomethyl ether, propylene glycol monoacetate, OK73 thinner, cyclohexanone, and ν-butyrolactone.

10. The rework method of the photolithography process according to claim 7, characterized in that, The process parameters of the baking treatment include: a baking temperature of 150 °C to 220 °C; a baking time of 15 seconds to 500 seconds.

11. The rework method of the photolithography process according to claim 7, wherein The wafer surface further has: a spin-coated organic carbon layer, and a silicon-containing photoresist antireflection layer located on the spin-coated organic carbon layer.

12. The rework method of the lithography process according to claim 11, characterized in that, The first negative photoresist layer is spin-coated on the silicon-containing photoresist antireflection layer.

13. The rework method of the lithography process according to claim 11, characterized in that, The second negative photoresist layer is spin-coated on the silicon-containing photoresist antireflection layer.

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