An anti-collapse photoresist rinse liquid and a photolithography method for forming a photoresist pattern

Abstract

The present invention discloses an anti-collapse photoresist rinse liquid and a photolithography method for forming a photoresist pattern, which comprises a non-ionic surfactant, an anionic surfactant, an organic base and a solvent. The non-ionic surfactant is:; The anionic surfactant is isooctyl ether phosphate or isooctyl polyoxyethylene ether phosphate. The present invention adopts an alkynediol-based non-ionic surfactant, which has the function of double tails with interconnected bipolar groups, and synergistically acts with the anionic surfactant to improve the activity of the surfactant while reducing the surface tension of the rinse liquid, thereby reducing the internal stress of the photoresist lines and preventing collapse; The double - OH in the alkynediol reacts with the unreacted free carboxylic acid in the photoresist during development to form a hydrophobic material surface layer, improving the line edge roughness and the image surface roughness; By cross-linking reaction between the organic base and the functional groups on the photoresist surface, the mechanical properties are improved to further prevent collapse.

Description

Technical Field

[0001] The present invention relates to the technical field of photoresist rinsing, and particularly relates to an anti-collapse photoresist rinsing solution and a photolithography method for forming a photoresist pattern. Background Art

[0002] In the photolithography process, after the photoresist is developed, a rinsing solution is required to rinse the photoresist pattern to reduce the residue of the developer on the surface of the photoresist pattern. In the prior art, deionized water is generally used to rinse the photoresist pattern. With the continuous progress of technology and the change of market demand, semiconductor technology will continue to develop in the direction of higher performance, lower power consumption, and smaller size. Currently, the semiconductor node has developed to below 14nm, the aspect ratio of the photolithography pattern has increased sharply, and the collapse and defects of the photoresist pattern structure have become factors that cannot be ignored in affecting the quality of the photoresist.

[0003] The collapse of the photoresist pattern is one of the common problems in the photolithography process. In the photolithography technology of semiconductor manufacturing, the collapse of the photoresist pattern is a key defect, which refers to the phenomenon that the photoresist line bends, breaks, or loses adhesion to the substrate on the wafer surface. The main reasons for the collapse of the photoresist pattern include the capillary force during the post-development rinsing process and the surface tension of the rinsing deionized water. The capillary force is determined by the surface tension and contact angle of the rinsing solution, and the stress in the photoresist line increases with the increase of the aspect ratio and the surface tension of water. During centrifugation or hard baking, the surface tension of water will be applied to the photoresist line, which may cause the collapse of the photoresist line. The stress in the hydrophobic photoresist is small, so the situation of collapse is less. Therefore, the negative photoresist is less likely to collapse because the exposed resin part undergoes a curing cross-linking reaction and has strong hydrophobicity. However, for positive photoresists, especially positive photoresists with a process node below 14nm, the exposed part contains a large number of -OH hydrophilic groups. Although the unexposed area is insoluble in the developer, the stress in the photoresist line increases, and at the same time, the line aspect ratio also increases, making it extremely easy to occur the defect of the collapse of the photoresist line.

[0004] The defect of the photoresist pattern is another common problem in the semiconductor manufacturing process. The generation of the defect of the photoresist pattern is mainly due to the fact that after the photoresist is exposed and developed, it still contains some hydrophobic groups, and these groups will adhere or accumulate on the surface of the photoresist pattern to form defects.

[0005] In addition, the roughness of the photoresist pattern is also an important standard for measuring the quality of the photoresist pattern. During the exposure and development rinsing process of the photoresist, the line edge roughness LER and the line width roughness LWR will also be affected.

[0006] Patent CN1947066A discloses a novel rinsing liquid that can modify the surface of an easily wettable anti-corrosion pattern with a contact angle below 40 degrees to a contact angle above 70 degrees, effectively preventing pattern collapse. A fluorine-containing compound is added to the rinsing liquid to increase its contact angle and reduce its surface tension, while not affecting the physical properties of the resist itself. However, it has no obvious effect on optimizing photoresist defects and pattern roughness.

[0007] In the industry, fluorosurfactants are mostly used to reduce the surface tension of the rinsing liquid to effectively prevent pattern collapse. However, it has no obvious improvement in optimizing line edge roughness, image surface roughness, and preventing resist adhesion, etc. At the same time, there are still certain problems in aspects such as the foaming property and residual amount of the surfactant. At the same time, various fluorosurfactants or other surfactants are applied to photoresist rinsing liquids and cleaning liquids, but the requirements for the composition are different in the two application scenarios. Among them, the rinsing liquid is used to rinse and remove the development residues of the photoresist pattern after development. The main function of the surfactant used is to reduce the surface tension of the wafer surface after rinsing, thereby reducing the internal stress of the photoresist lines and improving the defect of photoresist pattern collapse; while the photoresist cleaning liquid is used to remove the photoresist pattern, and the main function of its surfactant is to make each component disperse more evenly, facilitating the removal of the photoresist.

[0008] Therefore, it is of great significance to research and develop a rinsing liquid that can effectively prevent photoresist pattern collapse and optimize the surface defects and surface roughness of photoresist lines. Summary of the Invention

[0009] In view of the deficiencies in the prior art, the present invention provides an anti-collapse photoresist rinsing liquid and a photolithography method for forming a photoresist pattern. The alkynediol nonionic surfactant is used, which has the function of a double-tail with interconnected bipolar groups, has excellent wettability to the substrate and good foam suppression and defoaming effects; and the double - OH therein undergoes an esterification reaction with the unreacted free carboxylic acid in the photoresist during development, generating a hydrophobic material surface layer, improving the line edge roughness and image surface roughness; the alkynediol nonionic surfactant and the ionic surfactant act synergistically to increase the activity of the alkynediol nonionic surfactant while reducing the surface tension of the rinsing liquid, thereby reducing the internal stress of the photoresist lines and preventing collapse; in addition, through the crosslinking reaction of the organic base with the functional groups on the photoresist surface, the mechanical properties are improved, further preventing collapse.

[0010] To solve the above technical problems, in the first aspect of the present invention, an anti-collapse photoresist rinsing liquid is provided, which includes a nonionic surfactant, an anionic surfactant, an organic base, and a solvent.

[0011] The nonionic surfactant is: ;

[0012] The anionic surfactant is isooctanol ether phosphate or isooctanol polyoxyethylene ether phosphate.

[0013] The present invention uses an alkynediol nonionic surfactant, which has the function of a double-tail with interconnected bipolar groups. Its arrangement on the interface is lying flat on the interface. At a relatively high surface pressure, the molecules are closely arranged, and at a relatively low surface tension, the molecules are more extended, resulting in excellent wettability of the substrate and good foam suppression and defoaming effects. Through the synergistic effect of the anionic surfactant isooctanol ether phosphate or isooctanol polyoxyethylene ether phosphate and the alkynediol nonionic surfactant, the activity of the surfactant is improved, the surface tension of the rinsing liquid is further reduced, and the stress in the photoresist lines is reduced, thereby preventing structure collapse.

[0014] In the present invention, the double - OH in the alkynediol nonionic surfactant reacts with the free carboxylic acid that is not completely developed in the photoresist to form a hydrophobic material surface layer, improving the line edge roughness and the image surface roughness. The surfactant effectively prevents the adhesion of the residual hydrophobic groups after development to the photoresist surface by improving the surface energy of the hydrophobic groups, thereby playing a role in preventing collapse, photoresist adhesion, and improving the line edge roughness and the image surface roughness.

[0015] In the present invention, an organic base reacts with the functional groups on the surface to improve the mechanical properties of the surface, further avoiding collapse or deformation and improving the collapse rate.

[0016] Further, the organic base is selected from one or more of long-chain alkanolamines with C10 - C15.

[0017] Further, the surface tension of the rinsing liquid at 20°C is 20 - 40 mN / m. A relatively low surface tension is achieved through the synergistic effect of the alkynediol nonionic surfactant and the anionic surfactant, effectively preventing collapse.

[0018] Further, the mass ratio of the nonionic surfactant to the anionic surfactant is 1:0.3 - 0.6.

[0019] Further, the concentration of the nonionic surfactant in the rinsing liquid is 300 - 1000 ppm, preferably 400 - 800 ppm.

[0020] Further, the concentration of the anionic surfactant in the rinsing liquid is 100 - 500 ppm, preferably 200 - 400 ppm.

[0021] Further, the solvent is water, preferably ultrapure water.

[0022] Further, the concentration of the organic base in the rinsing solution is 100 - 1000 ppm, preferably 200 - 600 ppm.

[0023] The second aspect of the present invention provides a lithography method for forming a photoresist pattern, comprising the following steps:

[0024] S1. Spin-coating a photoresist on a substrate to form a photoresist layer;

[0025] S2. Exposing, baking, and developing the photoresist layer;

[0026] S3. Rinsing the developed photoresist layer with the rinsing solution described in the first aspect to remove the developing residues, thereby obtaining a photoresist pattern.

[0027] Further, the photoresist is an ArF photoresist, an EUV photoresist, or a KrF photoresist.

[0028] Further, the thickness of the photoresist layer is 50 - 5000 nm, which can be set according to actual requirements.

[0029] Advantages of the present invention:

[0030] The anti-collapse photoresist rinsing solution of the present invention is used to rinse the developed photoresist pattern to remove the developing residues. An alkynediol-based nonionic surfactant is adopted, which has the function of a double-tail with interconnected bipolar groups. Its arrangement mode on the interface is lying flat on the interface. When the surface pressure is relatively high, the molecules are closely arranged. When the surface tension is relatively low, the molecules are more stretched, resulting in excellent wettability to the substrate, good foam suppression and defoaming effects, and reduction of the surface tension.

[0031] The present invention synergistically uses an anionic surfactant, isooctyl ether phosphate or isooctyl polyoxyethylene ether phosphate, and an alkynediol-based nonionic surfactant to improve the activity of the surfactant, further reduce the surface tension of the rinsing solution, reduce the stress inside the photoresist lines, and thus prevent the structure from collapsing.

[0032] In the present invention, the double - OH in the alkynediol-based nonionic surfactant reacts with the free carboxylic acid that is not completely developed in the photoresist to form a hydrophobic material surface layer, improving the line edge roughness and the image surface roughness. The surfactant effectively prevents the adhesion of the hydrophobic groups of the developing residues to the photoresist surface by improving the surface energy of the hydrophobic groups, thereby playing the role of preventing collapse, photoresist adhesion, and improving the line edge roughness and the image surface roughness.

[0033] The present invention improves the mechanical properties of the surface by the crosslinking reaction of the organic base with the functional groups on the photoresist surface, further avoiding collapse or deformation and improving the collapse rate. Description of the Drawings

[0034] To more clearly illustrate the technical solution of the present invention, the accompanying drawings required for use in the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0035] Figure 1 It is the SEM image of the photoresist pattern obtained in Example 1 of the present invention;

[0036] Figure 2 It is the SEM image of the photoresist pattern obtained in Example 2 of the present invention;

[0037] Figure 3 It is the SEM image of the photoresist pattern obtained in Example 3 of the present invention;

[0038] Figure 4 It is the SEM image of the photoresist pattern obtained in Comparative Example 1 of the present invention;

[0039] Figure 5 It is the SEM image of the photoresist pattern obtained in Comparative Example 2 of the present invention;

[0040] Figure 6 It is the SEM image of the photoresist pattern obtained in Comparative Example 3 of the present invention;

[0041] Figure 7 It is the SEM image of the photoresist pattern obtained in Comparative Example 4 of the present invention;

[0042] Figure 8 It is the SEM image of the photoresist pattern obtained in Comparative Example 5 of the present invention;

[0043] Figure 9 It is the SEM image of the photoresist pattern obtained in Comparative Example 6 of the present invention. Specific Embodiments

[0044] The technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0045] This embodiment relates to an anti-collapse photoresist rinse solution, which includes a non-ionic surfactant, an anionic surfactant, an organic base, and a solvent. The non-ionic surfactant is: ; The anionic surfactant is isooctyl ether phosphate or isooctyl polyoxyethylene ether phosphate.

[0046] This embodiment uses an alkynediol nonionic surfactant, which functions as a double-tailed surfactant with interconnected bipolar groups. Its arrangement on the interface is lying flat on the interface. At a relatively high surface pressure, the molecules are closely arranged, and at a relatively low surface tension, the molecules are more extended, resulting in excellent wettability of the substrate and good foam inhibition and defoaming effects. Through the synergistic effect of an anionic surfactant such as isooctyl ether phosphate or isooctyl polyoxyethylene ether phosphate and an alkynediol nonionic surfactant, the activity of the surfactant is enhanced, and the surface tension of the rinsing liquid is further reduced. The surface tension of the rinsing liquid at 20 °C is as low as 20 - 40 mN / m, reducing the stress in the photoresist lines, thereby preventing structure collapse; through the esterification reaction between the double - OH in the alkynediol nonionic surfactant and the unreacted free carboxylic acid in the photoresist during development, a hydrophobic material surface layer is formed, improving the line edge roughness and image surface roughness. The surfactant effectively prevents the adhesion of residual hydrophobic groups during development to the photoresist surface by improving the surface energy of the hydrophobic groups, thus playing a role in preventing collapse, photoresist adhesion, and improving line edge roughness and image surface roughness; through the cross - linking reaction between an organic base and the functional groups on the surface, the mechanical properties of the surface are improved, further avoiding collapse or deformation and improving the collapse rate.

[0047] As a preferred embodiment, the organic base is selected from one or more of the long - chain alkanolamines with C10 - C15.

[0048] As a preferred embodiment, the mass ratio of the nonionic surfactant to the anionic surfactant is 1:0.3 - 0.6; the concentration of the nonionic surfactant in the rinsing liquid is 300 - 1000 ppm, preferably 400 - 800 ppm; the concentration of the anionic surfactant in the rinsing liquid is 100 - 500 ppm, preferably 200 - 400 ppm.

[0049] As a preferred embodiment, the solvent is water, preferably ultrapure water.

[0050] As a preferred embodiment, the concentration of the organic base in the rinsing liquid is 100 - 1000 ppm, preferably 200 - 600 ppm.

[0051] Another embodiment relates to a lithography method for forming a photoresist pattern, including the following steps:

[0052] S1. Spin - coat a photoresist on a substrate to form a photoresist layer;

[0053] Among them, the photoresist is an ArF photoresist, an EUV photoresist, or a KrF photoresist, and the thickness of the photoresist layer is 50 - 5000 nm, which can be set according to actual requirements;

[0054] S2. Expose, bake, and develop the photoresist layer;

[0055] S3. Rinse the developed photoresist layer with the rinsing liquid described in the first aspect to remove the developing residues, obtaining a photoresist pattern.

[0056] Example 1

[0057] This example relates to a photolithography method for forming a photoresist pattern, including the following steps:

[0058] (1) Spin-coat an ArF photoresist on a silicon substrate to form a photoresist layer film with a thickness of 300 nm;

[0059] (2) Use an ArF excimer stepper (ASML XT1900) to expose with a light source of wavelength 193 nm, and then heat-treat at 130 °C for 30 seconds;

[0060] (3) Develop the exposed photoresist in a 2.38% tetramethylammonium hydroxide solution for 60 seconds to form a specific primary photoresist pattern;

[0061] (4) Rinse the developed primary photoresist pattern with a photoresist rinsing liquid for 5 seconds and then spin-dry, and heat-treat at 100 °C for 60 seconds to dry, obtaining a photoresist pattern, wherein the rinsing liquid includes a nonionic surfactant A with a concentration of 600 ppm: , an anionic surfactant B: isooctyl alcohol ether phosphate with a concentration of 300 ppm, 10-amino-1-decanol with a concentration of 300 ppm, and the rest is ultrapure water.

[0062] Example 2

[0063] The difference between this example and Example 1 is that the concentration of the anionic surfactant B in the rinsing liquid is 200 ppm, and other steps and parameters remain unchanged.

[0064] Example 3

[0065] The difference between this example and Example 1 is that the concentration of the nonionic surfactant A in the rinsing liquid is 800 ppm, and other steps and parameters remain unchanged.

[0066] Comparative Example 1

[0067] The difference between this comparative example and Example 1 is that the rinsing liquid is ultrapure water, and other steps and parameters remain unchanged.

[0068] Comparative Example 2

[0069] The difference between this comparative example and Example 3 is that the rinsing liquid does not contain the anionic surfactant B, and other steps and parameters remain unchanged.

[0070] Comparative Example 3

[0071] The difference between this comparative example and Example 3 is that the rinsing liquid does not contain nonionic surfactant A, and other steps and parameters remain unchanged.

[0072] Comparative Example 4

[0073] The difference between this comparative example and Example 3 is that the rinsing liquid does not contain organic base, and other steps and parameters remain unchanged.

[0074] Comparative Example 5

[0075] The difference between this comparative example and Example 2 is that the nonionic surfactant A in the rinsing liquid is replaced with a fluorosurfactant: , and other steps and parameters remain unchanged.

[0076] Comparative Example 6

[0077] The difference between this comparative example and Comparative Example 5 is that the rinsing liquid does not contain anionic surfactant B, and other steps and parameters remain unchanged.

[0078] In Examples 1 - 3 and Comparative Examples 1 - 6, different rinsing liquids were used to rinse the photoresist, and the performance parameters of the rinsing liquids and the resulting photoresist patterns are shown in Table 1. Among them, surface tension: The static surface tension of the rinsing composition at 20°C was measured by a JK99C full-automatic tensiometer using the platinum plate method; bubble generation amount: The number of bubbles (number of particles of 0.15 μm) in the rinsing liquid was measured by a liquid particle counter (Rion 18F); surface topography: The topography and dimensions of the photolithographic pattern surface were observed and measured by SEM, including: collapse rate, surface roughness, and whether there are adhesion defects, etc.

[0079] Table 1

[0080]

[0081] Among them, the meanings of the parameters in Table 1 are as follows:

[0082] A: No collapse, fully meeting the process requirements; A1: A small amount of collapse, basically meeting the process requirements; A2: A large amount of collapse, unable to meet the process requirements. Defect rate: Refers to the defect ratio on the pattern surface caused by photoresist pattern adhesion, patch residue, etc.; D: No defects, fully meeting the process requirements; D1: A small number of defects, basically meeting the process requirements; D2: A large number of defects, unable to meet the process requirements. Surface roughness: Refers to the roughness fineness of the line end face; R: Good roughness, fully meeting the process requirements; R1: Slightly poor roughness, basically meeting the process requirements; R2: Very poor roughness, unable to meet the process requirements.

[0083] As can be seen from Table 1, when the photoresist rinse liquid of the present invention is used to rinse the photoresist pattern (Examples 1-3), the obtained photoresist pattern has excellent resolution, no pattern collapse and defects, and at the same time, the pattern roughness is also good, which is consistent with Figures 1 - 3 the results. In Comparative Example 1, the photoresist pattern was rinsed with ultrapure water. Since ultrapure water has a high surface tension, the capillary force and the internal stress in the photoresist pattern during the rinsing process increased greatly, resulting in serious pattern collapse. At the same time, the residual hydrophobic groups after development still could not be completely removed by the rinsing of water, leading to a large number of adhesion defects. Refer to Figure 4 .

[0084] From the comparison between Comparative Example 2 and Example 3, it can be seen that when surfactant A is used alone in the rinse liquid without synergistic action with surfactant B, its surface activity in the aqueous solution is lower than that of the compound system. The residual small amount of hydrophobic groups after development could not be completely washed away, resulting in a small amount of adhesion. Refer to Figure 5 , and at the same time, the amount of bubbles generated is higher than that when used in combination, which has a serious adverse effect on the photolithography process.

[0085] From the comparison between Comparative Example 3 and Example 3, it can be seen that when surfactant B is used alone in the rinse liquid, its wettability is greatly weakened, and at the same time, it is not compounded with surfactant A, and its surface activity in the aqueous solution is much lower than that of the compound system. Therefore, obvious pattern collapse occurred. Refer to Figure 6 .

[0086] From the comparison between Comparative Example 4 and Example 3, it can be seen that the lack of cross-linking effect of the organic base in the rinse liquid results in a decrease in mechanical properties, leading to a large number of collapses. Refer to Figure 7 .

[0087] In Comparative Examples 5-6, surfactant A was replaced with perfluoropolyether carboxylic acid, a fluorinated surfactant. Although it has a low surface tension, since the -COOH functional group it contains cannot undergo an esterification reaction with the free carboxylic acid in the photoresist pattern to form a hydrophobic material, its adhesion defects are serious, and at the same time, the surface roughness of the pattern is significantly deteriorated. Refer to Figures 8 - 9 , and in addition, due to the poor water solubility of perfluoropolyether carboxylic acid, the amount of bubbles in the entire rinse liquid system increases significantly, which has a serious adverse effect on the photolithography process.

[0088] In summary, the anti-collapse photoresist rinse liquid of the present invention is used to rinse the developed photoresist pattern to remove the development residues. An alkynediol nonionic surfactant is adopted, which has the function of a double-tail with interconnected bipolar groups. Its arrangement mode on the interface is lying flat on the interface. When the surface pressure is large, the molecules are closely arranged; when the surface tension is low, the molecules are more stretched, resulting in excellent wettability of the substrate, good foam inhibition and defoaming effects, and reduction of surface tension. Through the synergistic effect of the anionic surfactant isooctyl ether phosphate or isooctyl polyoxyethylene ether phosphate and the alkynediol nonionic surfactant, the activity of the surfactant is improved, the surface tension of the rinse liquid is further reduced, and the stress in the photoresist line is reduced, thereby preventing structure collapse. Through the esterification reaction of the double - OH in the alkynediol nonionic surfactant with the incompletely developed free carboxylic acid in the photoresist, a hydrophobic material surface layer is formed, improving the line edge roughness and the image surface roughness. The surfactant effectively prevents the adhesion of the hydrophobic groups of the development residues to the photoresist surface by improving the surface energy of the hydrophobic groups, thereby playing a role in preventing collapse, photoresist adhesion, and improving the line edge roughness and the image surface roughness. Through the cross - linking reaction of the organic base with the functional groups on the surface, the mechanical properties of the surface are improved, further avoiding collapse or deformation and improving the collapse rate.

[0089] The present invention has been described in detail above in combination with specific embodiments and exemplary examples, but these descriptions should not be construed as limiting the present invention. Those skilled in the art understand that without departing from the spirit and scope of the present invention, various equivalent substitutions, modifications or improvements can be made to the technical solutions and their implementation manners of the present invention, and these all fall within the scope of the present invention. The protection scope of the present invention is subject to the appended claims.

Claims

1. An anti-collapse photoresist rinse solution, characterized in that, It includes a nonionic surfactant, an anionic surfactant, an organic base and a solvent. The non-ionic surfactant is: ; The anionic surfactant is isooctanol ether phosphate or isooctanol polyoxyethylene ether phosphate. The surface tension of the rinsing liquid at 20 °C is 20 - 40 mN / m; the mass ratio of the nonionic surfactant to the anionic surfactant is 1:0.3 - 0.6; the solvent is water; the concentration of the organic base in the rinsing liquid is 100 - 1000 ppm.

2. The anti-collapse photoresist rinse liquid according to claim 1, wherein, The organic base is selected from one or more of C10 - C15 long-chain alkanolamines.

3. The anti-collapse photoresist rinse liquid according to claim 1, wherein The concentration of the nonionic surfactant in the rinsing liquid is 300 - 1000 ppm.

4. The anti-collapse photoresist rinse solution according to claim 1, wherein The concentration of the anionic surfactant in the rinsing liquid is 100 - 500 ppm.

5. A lithography method for forming a photoresist pattern, characterized in that, It includes the following steps: S1. Spin-coat a photoresist on a substrate to form a photoresist layer. S2. Expose, bake and develop the photoresist layer. S3. Rinse the developed photoresist layer with the rinsing liquid according to any one of claims 1 - 4 to remove the developing residues, obtaining a photoresist pattern.

6. The photolithography method for forming a photoresist pattern according to claim 5, wherein, The photoresist is an ArF photoresist, an EUV photoresist or a KrF photoresist.

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