Method for manufacturing a semiconductor device

Abstract

A method of fabricating a semiconductor device includes forming a photoresist layer on a substrate. A portion of the photoresist layer is exposed to radiation using a mask. The photoresist layer is treated with a basic gas. The photoresist layer is developed to form a patterned photoresist layer on the substrate.

Description

Technical Field

[0001] This disclosure relates to a method for manufacturing a semiconductor device, and more particularly to a photolithography process for manufacturing a semiconductor device. Background Technology

[0002] As electronic devices (such as personal computers, tablets, mobile phones, and other electronic devices) become increasingly smaller, the size of individual components in these devices must also shrink. Components can also be semiconductor devices, which are typically formed by continuously depositing layers of dielectric, conductive, and / or semiconductor materials on a semiconductor substrate, and then patterning the layers using photolithography.

[0003] Photolithography is a common method used in the manufacture of integrated circuits (ICs). It is the process of transferring a geometric pattern onto a substrate or a layer on a substrate. The basic processes of photolithography include photoresist coating, exposure, and development. The exposure step involves exposing specific areas of the photoresist layer to radiation, while the development step involves applying a developer to the photoresist to obtain the desired pattern. Summary of the Invention

[0004] According to some embodiments of this disclosure, a method of manufacturing a semiconductor device includes forming a photoresist layer on a substrate. A portion of the photoresist layer is exposed to radiation using a mask. The photoresist layer is treated with an alkaline gas. The photoresist layer is developed to form a patterned photoresist layer on the substrate.

[0005] In the above embodiments, the pH value of the alkaline gas dissolved in water is 8 to 9.

[0006] In the above embodiments, the method further includes performing post-exposure baking before processing the photoresist layer.

[0007] In the above embodiments, the step of processing the photoresist layer includes applying an alkaline gas and a carrier gas onto the photoresist layer.

[0008] In the above embodiments, the carrier gas includes an inert gas, nitrogen, or a combination thereof.

[0009] In the above embodiments, the photoresist layer comprises positive photoresist, and the step of developing the photoresist layer comprises negative development.

[0010] In the above embodiments, the photoresist layer includes positive photoresist, and the step of developing the photoresist layer includes positive development.

[0011] According to some embodiments of this disclosure, a method for manufacturing a semiconductor device includes coating a photoresist layer on a substrate. The photoresist layer is exposed to radiation using a mask. The photoresist layer on the substrate is subjected to post-exposure baking. A first gas is removed from a chamber. After removing the first gas from the chamber, the top surface of the photoresist layer is modified in the chamber with a second gas. A developer is applied to the photoresist layer.

[0012] In the above embodiments, the second gas is alkaline when dissolved in water.

[0013] In the above embodiments, the second gas contains ammonia, amine, or a combination thereof.

[0014] In the above embodiments, the post-exposure baking is performed at a temperature of 70°C to 110°C.

[0015] In the above embodiments, the duration of modifying the top surface of the photoresist layer is less than 1 minute.

[0016] In the above embodiments, the pressure in the chamber is 1 torr to 100 torr.

[0017] In the above embodiments, the developer comprises an aqueous solution. In the above embodiments, the developer comprises an organic solvent.

[0018] According to some embodiments of this disclosure, a method of manufacturing a semiconductor device includes forming a photoresist layer on a substrate, wherein the photoresist layer contains a photoacid generating agent. A first region of the photoresist layer is exposed to radiation to generate photoacid within the photoresist layer. The photoresist layer on the substrate is then subjected to post-exposure baking. An alkaline gas is flowed over the photoresist layer to react with the photoacid within the photoresist layer. A developer is applied to the photoresist layer to remove a second region of the photoresist layer, wherein the second region is not exposed to radiation.

[0019] In the above embodiments, the developer is selected from the group consisting of ethers, glycol ethers, aromatic hydrocarbons, ketones, esters, or combinations thereof.

[0020] In the above embodiments, after the developer is applied to the photoresist layer, the plurality of sidewalls of the first region of the photoresist layer are substantially perpendicular to the bottom surface of the photoresist layer.

[0021] In the above embodiments, the duration for which the alkaline gas flows on the photoresist layer is 30 to 60 seconds.

[0022] In the above embodiments, the flow of alkaline gas on the photoresist layer includes the flow of inert gas or nitrogen gas with the alkaline gas. Attached Figure Description

[0023] A better understanding of the features disclosed herein will be achieved by reading the following detailed description in conjunction with the accompanying drawings. It should be noted that, as is standard practice in the industry, many features are not drawn to scale. In fact, for clarity of discussion, the dimensions of many features may be arbitrarily scaled.

[0024] Figure 1 A schematic diagram illustrating an intermediate stage of a method for manufacturing a semiconductor device according to some embodiments of the present disclosure.

[0025] Figure 2 A schematic diagram illustrating an intermediate stage of a method for manufacturing a semiconductor device according to some embodiments of the present disclosure.

[0026] Figure 3 A schematic diagram illustrating an intermediate stage of a method for manufacturing a semiconductor device according to some embodiments of the present disclosure.

[0027] Figure 4A and Figure 4B A schematic diagram illustrating an intermediate stage of a method for manufacturing a semiconductor device according to some embodiments of the present disclosure. Detailed Implementation

[0028] The following disclosure provides numerous different embodiments or illustrations to implement various features of the provided subject. The specific examples of components and configurations described below are for the purpose of simplifying this disclosure. These are, of course, merely illustrative and are not intended to be limiting. For example, a description in which a first feature is formed on or above a second feature includes embodiments where the first and second features are in direct contact, as well as embodiments where other features are formed between the first and second features such that the first and second features are not in direct contact. Furthermore, element symbols and / or letters are repeated in various specific examples in this disclosure. This repetition is for the purpose of simplifying and clarifying the description and does not imply a relationship between the various discussed embodiments and / or configurations.

[0029] Furthermore, spatially relative terms, such as "below," "below," "lower," "above," and "upper," are used to facilitate the description of the relationship between a part or feature depicted in the accompanying drawings and other parts or features. In addition to the directions depicted in the drawings, spatially relative terms also include different orientations of the elements during use or operation. The device may be oriented in other ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used in this disclosure can also be interpreted in this way.

[0030] Generally, in photolithography, a photoresist layer is first formed on a substrate. Next, the photoresist layer is exposed to a radiation source through a photomask. This radiation exposure causes chemical reactions in the exposed portions of the photoresist layer. Then, the photoresist layer is developed using a developer to form a default pattern within it.

[0031] There are two types of photoresist: positive photoresist and negative photoresist. Both positive and negative photoresist undergo chemical structure changes upon exposure to radiation, thereby altering their solubility in developer. Generally, after exposure to radiation, the exposed portion of positive photoresist breaks chemical bonds and changes its solubility in developer. On the other hand, exposure of negative photoresist initiates a cross-linking reaction, thus causing the exposed portion of negative photoresist to change its solubility in developer.

[0032] Regardless of whether the photoresist is positive or negative, the resulting pattern depends on the type of developer used to develop it. For example, when the developer is an aqueous solution-based developer (e.g., tetramethylammonium hydroxide (TMAH) solution), some positive photoresist that is insoluble in the developer solution will provide a positive pattern (i.e., the exposed portions are removed by the developer), which is positive development. On the other hand, when the developer is an organic solvent, the same photoresist will provide a negative pattern (i.e., the unexposed portions are removed by the developer), which is negative development. Furthermore, the unexposed portions of negative photoresist are removed by tetramethylammonium hydroxide, while the exposed portions undergo a cross-linking reaction upon exposure to radiation and can remain on the substrate after development. Alternatively, the exposed portions of negative photoresist can be removed by using an organic solvent as the developer, while the unexposed portions remain on the substrate.

[0033] Typically, photoresist layers contain a photoacid generator (PAG), which absorbs exposure energy and generates photoacid. Photoacid can act as a chemical amplifying factor in the solubility of the converted photoresist. However, photoacid generated primarily in the exposed portions of the photoresist layer can also diffuse to unexposed areas, particularly the upper surface with a larger amount of photoacid. Therefore, after development, patterned photoresist layers typically exhibit a T-topping pattern profile, indicating that the patterned photoresist layer retained on the substrate tapers from the upper surface to the lower surface. In other words, the width of the upper surface of the patterned photoresist layer is typically greater than the width of the lower surface, and the sidewalls of the patterned photoresist layer are sloping. Consequently, the pattern exhibits a larger critical dimension (CD) and less than ideal critical dimension uniformity.

[0034] According to some embodiments of this disclosure, a method for manufacturing a semiconductor device is provided, in which photoresist is treated with an alkaline gas after exposure. The alkaline gas reacts with photoacids, particularly diffusing to the unexposed portions of the photoresist, thereby reducing the T-shaped pattern profile of the photoresist and optimizing the uniformity of critical dimensions.

[0035] Figures 1 to 4B Schematic diagrams illustrating intermediate stages of a method for manufacturing a semiconductor device according to some embodiments of this disclosure. Figure 1 As shown, a photoresist layer 120 is formed on a substrate 110. The substrate 110 may be a semiconductor substrate, such as silicon, germanium, silicon-germanium, or a combination thereof. The substrate may be a wafer, such as a silicon wafer. In some embodiments, the substrate 110 may comprise layers on a semiconductor substrate. In some embodiments, the photoresist layer 120 is a photosensitive layer whose chemical properties can be altered under photochemical radiation. In some embodiments, the photoresist layer 120 is a positive photoresist. In some embodiments, the photoresist layer 120 contains a photoacid generator. In some embodiments, the photoresist layer 120 is formed using, for example, a spin-on coating process, a dip-coating method, an air-knife coating method, a curtain coating method, a wire-bar coating method, a gravure coating method, a lamination method, an extrusion coating method, or a combination thereof. The thickness of the photoresist layer depends on the default pattern and its subsequent application.

[0036] Please see Figure 2A mask (or photomask) 130 is placed on the photoresist layer 120, and an exposure radiation source provides radiation 135 to the photoresist layer 120 through the mask 130. In some embodiments, the exposure to radiation is performed in a photolithography tool that includes the mask 130 and the exposure radiation source. In some embodiments, the radiation 135 may be ultraviolet (UV), extreme ultraviolet (EUV), deep ultraviolet, electron beam, etc. In some embodiments, the radiation source is selected from a mercury vapor lamp, a xenon lamp, a carbon arc lamp, a KrF excimer laser light (wavelength 248 nm), an ArF excimer laser light (wavelength 193 nm), an F2 excimer laser light (wavelength 157 nm), or CO2 laser-excited tin plasma (extreme ultraviolet, wavelength 13.5 nm).

[0037] The first region 120A of the photoresist layer is exposed to radiation 135, while the second region (the remaining portion) 120B of the photoresist layer is not exposed (or is less exposed) to radiation 135. In some embodiments where the photoresist layer 120 is a positive photoresist, radiation 135 alters the chemical structure of the first region 120A, making it soluble in an aqueous-based developer, such as tetramethylammonium hydroxide solution. In this embodiment, the second region 120B should be insoluble in the developer solution. As described above, the first region 120A may generate photoacids after absorbing radiation 135. However, photoacid diffusion can cause the upper portion of the second region 120B to contain some photoacids, resulting in image blurring after the photolithography process.

[0038] After exposure to radiation 135, the photoresist layer 120 is selectively post-exposure baking (PEB) to complete the photoreaction driven by the exposure process. PEB helps to define the pattern. In some embodiments, the photoresist layer 120 is heated to a temperature of about 70°C to about 110°C for about 50 seconds to about 90 seconds. The temperature and duration of PEB depend on the default pattern and its subsequent application.

[0039] Then, please see Figure 3The photoresist layer 120 is treated with an alkaline gas 145. It should be understood that "basic gas" as used herein also refers to alkaline gas. The alkaline gas 145 can react with photoacids in the photoresist layer 120, such as photoacids diffused from the first region 120A to the second region 120B, particularly in the upper portion of the photoresist layer 120. In other words, the top surface of the photoresist layer 120 is modified by applying the alkaline gas 145. In some embodiments, this treatment is performed within a chamber 140. In this embodiment, other gases within the chamber 140 should be removed before the alkaline gas 145 is introduced into the chamber 140. In addition to the alkaline gas 145, a carrier gas may also be introduced into the chamber 140 along with the alkaline gas 145. In some embodiments, the carrier gas may be an inert gas (e.g., argon and helium), nitrogen (N2), or a combination thereof. In some embodiments, when the photoresist layer 120 in the chamber is treated with alkaline gas 145, the pressure in the chamber is from about 1 to about 100 torr.

[0040] In some embodiments, the alkaline gas 145 may be weakly alkaline when dissolved in water, for example, having a pH value of about 8 to about 9. If the pH value of the alkaline gas 145 is less than 8, the effect of reducing the T-shaped profile cannot be achieved. If the pH value of the alkaline gas 145 is greater than 9, the photoresist layer 120 will be damaged. In some embodiments, the alkaline gas 145 may contain ammonia (NH3), amine gas, or a combination thereof. In some embodiments, the duration of introducing the alkaline gas 145 into the chamber is less than 1 minute, for example, about 30 seconds to about 60 seconds. The duration of introducing the alkaline gas 145 affects the amount of photoacid; if the duration is more than 1 minute, the pattern produced by the photoresist layer 120 will become wider at the bottom surface than at the top surface. In some embodiments, the alkaline gas 145 does not contain liquid because liquid would damage the photoresist layer 120.

[0041] The photoresist layer 120 is then developed by applying a developer. In some embodiments, this development operation can be negative development or positive development. Generally, negative development can dissolve photoresist layers without photoacids, while positive development can dissolve photoresist layers with photoacids.

[0042] When negative development is performed, after development, the first region 120A (i.e., the exposed region) remains on the substrate 110, therefore the second region 120B is removed by the developer, as shown below. Figure 4A As shown. In Figure 4AIn the illustrated embodiments, the developer may comprise an organic solvent. The organic solvent may be any suitable solvent. For example, the developer is selected from the group consisting of ethers, glycol ethers, aromatic hydrocarbons, ketones, esters, or combinations of two or more of the foregoing. In some embodiments, the developer comprises propylene glycol methyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), toluene, methyl isobutyl ketone, cycloheptanone, tetrahydrofuran (THF), n-butyl acetate (nBA), and 2-heptanone (MAK), etc.

[0043] After negative development, a patterned photoresist layer (e.g.) Figure 4A The first region 120A shown has a small width and nearly perfectly straight sidewalls. In some embodiments, the width of the upper surface 121 of the first region 120A is substantially the same as the width of the bottom surface 123 of the first region 120A. In some embodiments, the sidewalls of the first region 120A are substantially perpendicular to the bottom surface 123 and / or the sidewalls of the first region 120A are substantially perpendicular to the upper surface 121.

[0044] In another embodiment, the development can be positive development, which utilizes an aqueous solution as the developing agent, such as tetramethylammonium hydroxide. Figure 4B As shown, during positive development, the second region 120B remains on the substrate 110, while the first region 120A is removed by the developer. Similarly, after positive development, a patterned photoresist layer (e.g., Figure 4B The second region 120B shown has a small width and nearly perfectly straight sidewalls. In some embodiments, the width of the upper surface 121 of the second region 120B is substantially the same as the width of the bottom surface 123 of the second region 120B. In some embodiments, the sidewalls of the second region 120B are substantially perpendicular to the bottom surface 123 and / or the sidewalls of the second region 120B are substantially perpendicular to the upper surface 121.

[0045] Generally, pattern resolution is poor in negative development. Excessive photoacid generation on the upper surface of the photoresist layer can produce T-shaped pattern outlines. However, some embodiments of this disclosure achieve optimized resolution by treating the exposed photoresist layer with an alkaline gas to reduce the concentration of photoacid on the upper surface. Therefore, after development, the patterned photoresist layer exhibits optimized critical dimensions and optimized critical dimension uniformity. Furthermore, the patterned photoresist layer reduces T-shaped pattern outlines. Additionally, the method disclosed herein is applicable to any type of pattern.

[0046] It should be understood that the steps described in the embodiments disclosed herein may be combined or omitted, and their order may be adjusted according to actual needs.

[0047] While this disclosure has described above with reference to several embodiments, other embodiments are still possible. Therefore, the spirit and scope of the appended claims are not limited to the embodiments described.

[0048] [Symbol Explanation]

[0049] 110: Substrate

[0050] 120: Photoresist layer

[0051] 120A: Zone 1

[0052] 120B: Second Zone

[0053] 121: Upper surface

[0054] 123: Bottom surface

[0055] 130: Curtain

[0056] 135: Radiation

[0057] 140: Chamber

[0058] 145: Alkaline gas.

Claims

1. A method for manufacturing a semiconductor device, characterized in that, Include: A photoresist layer is formed on the substrate; A portion of the photoresist layer is exposed to radiation using a mask; The photoresist layer is treated with an alkaline gas in a chamber at a pressure of 1 torr to 100 torr; and The photoresist layer is developed to form a patterned photoresist layer on the substrate.

2. The method for manufacturing a semiconductor device according to claim 1, characterized in that, The pH value when this alkaline gas dissolves in water is between 8 and 9.

3. The method for manufacturing a semiconductor device according to claim 1, characterized in that, Also includes: Before processing the photoresist layer, a post-exposure baking process is performed.

4. The method for manufacturing a semiconductor device according to claim 1, characterized in that, The step of processing the photoresist layer includes applying the alkaline gas and the carrier gas onto the photoresist layer.

5. The method for manufacturing a semiconductor device according to claim 4, characterized in that, The carrier gas contains an inert gas, nitrogen, or a combination thereof.

6. The method for manufacturing a semiconductor device according to claim 1, characterized in that, The photoresist layer contains positive photoresist, and the step of developing the photoresist layer includes negative development.

7. The method for manufacturing a semiconductor device according to claim 1, characterized in that, The photoresist layer contains positive photoresist, and the step of developing the photoresist layer includes positive development.

8. A method for manufacturing a semiconductor device, characterized in that, Include: A photoresist layer is coated on the substrate; A portion of the photoresist layer is exposed to radiation using a mask; The photoresist layer on the substrate is subjected to post-exposure baking; Remove the first gas from the chamber; After the first gas is removed from the chamber, the top surface of the photoresist layer is modified in the chamber using a second gas, wherein the pressure in the chamber is from 1 torr to 100 torr; and A developer is applied to the photoresist layer.

9. The method for manufacturing a semiconductor device according to claim 8, characterized in that, The second gas is alkaline when dissolved in water.

10. The method for manufacturing a semiconductor device according to claim 8, characterized in that, The second gas contains ammonia, amine, or a combination thereof.

11. The method for manufacturing a semiconductor device according to claim 8, characterized in that, The post-exposure baking is carried out at a temperature of 70°C to 110°C.

12. The method for manufacturing a semiconductor device according to claim 8, characterized in that, The duration of the modification of the top surface of the photoresist layer is less than 1 minute.

13. The method for manufacturing a semiconductor device according to claim 8, characterized in that, The developer contains an aqueous solution.

14. The method for manufacturing a semiconductor device according to claim 8, characterized in that, The developer contains organic solvents.

15. A method for manufacturing a semiconductor device, characterized in that, Include: A photoresist layer is formed on a substrate, wherein the photoresist layer contains a photoacid generator; A first region of the photoresist layer is exposed to radiation to generate photoacid within the photoresist layer; The photoresist layer on the substrate is subjected to post-exposure baking; An alkaline gas is circulated over the photoresist layer in a chamber to react with the photoacid within the photoresist layer, wherein the pressure in the chamber is from 1 torr to 100 torr; and A developer is applied to the photoresist layer to remove a second region of the photoresist layer that is not exposed to the radiation.

16. The method for manufacturing a semiconductor device according to claim 15, characterized in that, The developer is selected from the group consisting of ethers, glycol ethers, aromatic hydrocarbons, ketones, esters, or combinations thereof.

17. The method for manufacturing a semiconductor device according to claim 15, characterized in that, After the developer is applied to the photoresist layer, the plurality of sidewalls of the first region of the photoresist layer are substantially perpendicular to the bottom surface of the photoresist layer.

18. The method for manufacturing a semiconductor device according to claim 15, characterized in that, The alkaline gas is allowed to flow over the photoresist layer for 30 to 60 seconds.

19. The method for manufacturing a semiconductor device according to claim 15, characterized in that, The flow of the alkaline gas over the photoresist layer includes the flow of an inert gas or nitrogen over the alkaline gas.

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