An i-line photoresist, its preparation method and application

Abstract

The present invention discloses an i-line photoresist and its preparation method and application. The i-line photoresist composition disclosed in the present invention comprises the following components: resin, photosensitizer, organosilicon leveling agent and organic solvent; the resin comprises the following components in parts by weight: 80-90 parts of phenolic resin, 20-50 parts of resin C and 10-15 parts of resin D; the phenolic resin is at least one of phenolic resin A and phenolic resin B; the preparation method of the phenolic resin A comprises the following steps: reacting m-cresol, p-cresol, 3,5-xylenol and formaldehyde under the action of oxalic acid; the preparation method of the phenolic resin B comprises the following steps: reacting m-cresol, p-cresol and formaldehyde under the action of oxalic acid; the organosilicon leveling agent is polymethylphenylsiloxane. When the i-line photoresist composition of the present invention is used for i-line lithography, the obtained photoresist pattern has high photosensitivity and resolution.

Description

Technical Field

[0001] The present invention relates to an i-line photoresist, a preparation method thereof, and an application thereof. Background Art

[0002] Photoresist is a type of etch-resistant thin film material whose solubility changes after being irradiated by energy such as light beam, electron beam, and ion beam, and has extensive applications in the microfabrication of integrated circuits and semiconductor discrete devices. By coating the photoresist on semiconductor, conductor, and insulator materials, the remaining part after exposure and development protects the underlying layer, and then an etchant is used for etching to transfer the required micro-pattern from the mask to the substrate to be processed. Therefore, photoresist is a key material in microfabrication technology. According to different photochemical reaction mechanisms, photoresists are divided into positive photoresists and negative photoresists: after exposure, the solubility of the photoresist increases in the developer, and the one that obtains the same pattern as the mask is called a positive photoresist; after exposure, the solubility of the photoresist decreases or even becomes insoluble in the developer, and the one that obtains the opposite pattern to the mask is called a negative photoresist. Both types of photoresists have their own different application fields. Generally speaking, positive photoresists are more commonly used, accounting for more than 80% of the total amount of photoresists.

[0003] With the improvement of the integration degree of integrated circuits and the reduction of the processing line width, lithography technology has experienced a development process from g-line (436 nm) lithography, i-line (365 nm) lithography, to deep ultraviolet 248 nm lithography, and the current 193 nm lithography. Photoresists corresponding to each exposure wavelength have also emerged. With the change of the exposure wavelength, the composition and structure of the photoresist also change continuously to make the comprehensive performance of the photoresist meet the requirements of the corresponding integrated process. However, at present, the photosensitivity and resolution of i-line lithography need to be improved. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the defects of poor photosensitivity and low resolution of the photoresist pattern obtained by existing i-line lithography, thereby providing an i-line photoresist, a preparation method thereof, and an application thereof. The photoresist pattern obtained by using the i-line photoresist composition of the present invention has high photosensitivity and resolution when used for i-line lithography.

[0005] The present invention provides an i-line photoresist composition, which comprises the following components: resin, photosensitizer, organosilicon leveling agent, and organic solvent;

[0006] The resin comprises the following components in parts by weight: 80 - 90 parts of phenolic resin, 20 - 50 parts of resin C, and 10 - 15 parts of resin D;

[0007] The phenolic resin is at least one of phenolic resin A and phenolic resin B;

[0008] The preparation method of the phenolic resin A includes the following steps: reacting m-cresol, p-cresol, 3,5-xylenol and formaldehyde under the action of oxalic acid to obtain;

[0009] The preparation method of the phenolic resin B includes the following steps: reacting m-cresol, p-cresol and formaldehyde under the action of oxalic acid to obtain;

[0010] The structures of the resin C and the resin D are as follows:

[0011]

[0012]

[0013] The organosilicon leveling agent is polymethylphenylsiloxane.

[0014] In the present invention, the phenolic resin is preferably 80 parts by weight.

[0015] In the present invention, the phenolic resin is preferably phenolic resin A.

[0016] In the present invention, the phenolic resin is preferably phenolic resin B.

[0017] In the present invention, the phenolic resin is preferably a combination of phenolic resin A and phenolic resin B. When the phenolic resin is a combination of phenolic resin A and B, the mass ratio of phenolic resin A to phenolic resin B is preferably 2:7 - 7:2 (such as 1:1, 3.5:1, 3:1, 0.4:1, 0.5:1).

[0018] In the present invention, the resin C is preferably 30 parts by weight.

[0019] In the present invention, the resin D is preferably 10 parts by weight.

[0020] In one embodiment, the resin is composed of 80 - 90 parts of phenolic resin, 20 - 50 parts of resin C and 10 - 15 parts of resin D, wherein the phenolic resin is at least one of phenolic resin A and phenolic resin B.

[0021] In the present invention, the photosensitizer can be in the conventional parts by weight in the art, preferably 10 - 40 parts, such as 10 parts.

[0022] In the present invention, the concentration of the organosilicon leveling agent in the i-line photoresist composition can be the conventional concentration in the art, preferably 500 - 2000 ppm, such as 500 ppm, 1000 ppm or 2000 ppm.

[0023] In the present invention, the organic solvent can be in the conventional parts by weight in the art, preferably 450 - 800 parts, such as 450 parts.

[0024] In the present invention, the weight-average molecular weight of the silicone leveling agent is preferably 3,000 - 6,000.

[0025] In the present invention, the photosensitizer can be a conventional photosensitizer in the art, preferably 2,2',4,4'-tetrahydroxybenzophenone-1,2-naphthoquinone diazide-5-sulfonate.

[0026] In the present invention, the average esterification degree of the photosensitizer is preferably 60%.

[0027] In the present invention, the organic solvent can be a conventional solvent in the art, preferably one or more (such as one or two) of ether solvents, ester solvents, amide solvents, aromatic hydrocarbon solvents, and ketone solvents. The ether solvent can be one or more of ethylene glycol monomethyl ether, anisole, propylene glycol monoethyl ether, diethylene glycol monomethyl ether, and diethylene glycol diethyl ether; preferably ethylene glycol monomethyl ether. The ester solvent can be one or more of propylene glycol monomethyl ether acetate, butyl acetate, ethyl acetate, ethyl lactate, and γ-butyrolactone; preferably propylene glycol monomethyl ether acetate. The amide solvent can be dimethylacetamide. The aromatic hydrocarbon solvent can be xylene. The ketone solvent can be N-methylpyrrolidone. When using two solvents, the weight ratio of the first solvent to the second solvent may not be specifically limited, preferably 1:1 - 1:2, such as 1:1.25.

[0028] In a certain embodiment, the organic solvent is preferably one of ether solvents, ester solvents, amide solvents, aromatic hydrocarbon solvents, and ketone solvents.

[0029] In a certain embodiment, the organic solvents are preferably two kinds, namely ether solvent (the first solvent) and amide solvent (the second solvent).

[0030] In the preparation method of the phenolic resin A, the amount of m-cresol by weight can be a conventional amount in the art, preferably 30 - 80 parts, such as 65 parts.

[0031] In the preparation method of the phenolic resin A, the amount of p-cresol by weight can be a conventional amount in the art, preferably 20 - 50 parts, such as 35 parts.

[0032] In the preparation method of the phenolic resin A, the amount of 3,5-xylenol by weight can be a conventional amount in the art, preferably 1 - 10 parts, such as 5 parts.

[0033] In the preparation method of the phenolic resin A, the amount of oxalic acid by weight can be a conventional amount in the art, preferably 1 - 10 parts, such as 2 parts.

[0034] In the preparation method of phenolic resin A, formaldehyde preferably participates in the preparation of phenolic resin A in the form of formalin solution. The mass concentration of the formalin solution can be 36.9%. The formalin solution can be in the conventional parts by weight in the art, preferably 20 - 80 parts, such as 60 parts.

[0035] The preparation method of phenolic resin A can be carried out under a nitrogen atmosphere.

[0036] In the preparation method of phenolic resin A, it preferably includes the following steps: reacting m-cresol, p-cresol, 3,5-xylenol, formaldehyde, and oxalic acid, and adding oxalic acid once in the middle. When adding oxalic acid once in the middle, the amounts of oxalic acid added for the first and second times are the same. The total amount of oxalic acid used twice is 2 parts by weight.

[0037] In the preparation method of phenolic resin A, the reaction temperature can be the conventional reaction temperature in the art, preferably 40 - 100 °C, such as 40 °C, 60 °C, 100 °C.

[0038] In the preparation method of phenolic resin A, the reaction time can be the conventional reaction time in the art, preferably 4 - 10 hours, such as 7 hours.

[0039] The preparation method of phenolic resin A preferably includes the following steps: mixing m-cresol, p-cresol, 3,5-xylenol, formalin solution, and oxalic acid, reacting at 40 °C for 1 hour, then reacting at 60 °C for 2 hours, and finally adding oxalic acid and reacting at 100 °C for 4 hours.

[0040] In the preparation method of phenolic resin A, a distillation step can be further included to remove water and unreacted monomers.

[0041] In a certain scheme, the preparation method of phenolic resin A is as shown in Preparation Example 1.

[0042] In the preparation method of phenolic resin B, m-cresol can be in the conventional parts by weight in the art, preferably 30 - 80 parts, such as 55 parts.

[0043] In the preparation method of phenolic resin B, p-cresol can be in the conventional parts by weight in the art, preferably 20 - 50 parts, such as 45 parts.

[0044] In the preparation method of phenolic resin B, oxalic acid can be in the conventional parts by weight in the art, preferably 1 - 10 parts, such as 2 parts.

[0045] In the preparation method of the phenolic resin B, formaldehyde preferably participates in the preparation of the phenolic resin B in the form of a formalin solution. The concentration of the formalin solution can be 36.9 wt%. The formalin solution can be in the conventional amounts in the art by weight, preferably 20 - 80 parts, such as 60 parts.

[0046] The preparation method of the phenolic resin B can be carried out under a nitrogen atmosphere.

[0047] In the preparation method of the phenolic resin B, it preferably includes the following steps: mixing m-cresol, p-cresol, 3,5-xylenol, formaldehyde, and oxalic acid for reaction, and adding oxalic acid once in the middle. When adding oxalic acid once in the middle, the amounts of oxalic acid added for the first and second times are the same. The total amount of oxalic acid used twice is 2 parts by weight.

[0048] In the preparation method of the phenolic resin B, the reaction temperature can be the conventional reaction temperature in the art, preferably 40 - 100 °C, such as 40 °C, 60 °C, 100 °C.

[0049] In the preparation method of the phenolic resin B, the reaction time can be the conventional reaction time in the art, preferably 4 - 10 hours, such as 7 hours.

[0050] The preparation method of the phenolic resin B preferably includes the following steps: mixing m-cresol, p-cresol, formalin solution, and oxalic acid, reacting at 40 °C for 1 hour, then reacting at 60 °C for 2 hours, and finally adding oxalic acid and reacting at 100 °C for 4 hours.

[0051] In the preparation method of the phenolic resin B, it can further include a distillation step to remove water and unreacted monomers.

[0052] In a certain embodiment, the preparation method of the phenolic resin B is as shown in Preparation Example 2.

[0053] In one embodiment, the i-line photoresist composition is composed of the resin, the photosensitizer, the organosilicon leveling agent, and the organic solvent.

[0054] The present invention also provides a preparation method of an i-line photoresist composition, which includes the following steps: mixing the above components evenly.

[0055] In the preparation method, the mixing method can be the conventional mixing method in the art, preferably stirring.

[0056] In the preparation method, the mixing temperature can be the conventional mixing temperature in the art, preferably 50 °C.

[0057] In the described preparation method, the mixing time can be a conventional mixing time in the art, preferably 4 hours.

[0058] After the mixing, a filtration step may further be included. The filtration method can be a conventional method in the art, preferably filtration using a polytetrafluoroethylene membrane. The pore size of the polytetrafluoroethylene membrane is preferably 0.2 μm.

[0059] The present invention also provides a method for forming an i-line photoresist pattern, and the method includes the following steps:

[0060] Step 1: Coat the above-mentioned photoresist composition on the surface of a substrate, and then dry and bake to obtain a photoresist layer;

[0061] Step 2: Expose and develop the photoresist layer obtained in Step 1 to obtain a photoresist pattern.

[0062] In Step 1, the substrate can be a conventional substrate in the art, preferably a silicon wafer.

[0063] In Step 1, the coating method can be a conventional method in the art, preferably spin coating using a spin coater.

[0064] In Step 1, the thickness of the photoresist layer can be a conventional thickness in the art, preferably 0.75 μm.

[0065] In Step 1, the drying can be conventional drying in the art, preferably vacuum drying.

[0066] In Step 1, the baking temperature can be a conventional baking temperature in the art, preferably 100 °C.

[0067] In Step 1, the baking time is preferably 60 seconds.

[0068] In Step 2, the exposure can be a conventional operation in the art. In the present invention, it is preferred to detect the mask using a standard L / S = 1:1, and expose the obtained photoresist layer using the light source of i-line (i-line wavelength 365 nm).

[0069] In Step 2, the development can be a conventional operation in the art. Generally, the developer used is an aqueous solution of tetramethylammonium hydroxide (TMAH), such as an aqueous solution of TMAH with a mass fraction of 2.38%.

[0070] In Step 2, the development time is preferably 60 seconds.

[0071] On the basis of not violating the common knowledge in the art, the above preferred conditions can be combined arbitrarily to obtain various preferred examples of the present invention.

[0072] The resin of the present invention was self-made, and other reagents and raw materials used were all commercially available.

[0073] The positive and progressive effects of the present invention are as follows: The photoresist pattern formed by the photoresist composition of the present invention has good photosensitivity. The minimum exposure dose for its 0.5 μm 1:1 equal-space pattern is between 20 - 55 (0.5 μL / S (mJ / cm 2 ))), with high resolution, ranging from 0.23 - 0.53 μm, the edge of the line is a straight line, and the edge is narrow. Therefore, the photoresist composition of the present invention has good performance. Detailed implementation manners

[0074] The present invention will be further illustrated below by way of examples, but the present invention is not limited to the scope of the described examples. For the experimental methods without specific conditions noted in the following examples, they are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0075] Preparation Example 1 Preparation of phenolic resin A

[0076] 65 parts by weight of m-cresol, 35 parts by weight of p-cresol, 5 parts by weight of 3,5-xylenol, 60 parts by weight of formalin solution (mass fraction 36.9%) and 1 part by weight of oxalic acid were added to a reaction kettle, heated to 40 °C under nitrogen protection and reacted for 1 h, then reacted at 60 °C for 2 h, and finally 1 part by weight of oxalic acid was added and the temperature was raised to 100 °C and reacted for 4 h. Water and unreacted monomers were removed by distillation to obtain phenolic resin A.

[0077] Preparation Example 2 Preparation of phenolic resin B

[0078] The phenolic resin was synthesized by the following method: 55 parts by weight of m-cresol, 45 parts by weight of p-cresol, 60 parts by weight of formalin solution (mass fraction 36.9%) and 1 part by weight of oxalic acid were added to a reaction kettle, heated to 40 °C under nitrogen protection and reacted for 1 h, then reacted at 60 °C for 2 h, and finally 1 part by weight of oxalic acid was added and the temperature was raised to 100 °C and reacted for 4 h. Water and unreacted monomers were removed by distillation to obtain phenolic resin B.

[0079] In the following examples or comparative examples, the photoresist composition was prepared according to the following method:

[0080] Examples 1 - 26 and Comparative Examples 1 - 11

[0081] According to the proportions in Table 1, the phenolic resin, resin C, resin D, photosensitizer, organosilicon leveling agent and organic solvent were mixed, stirred at 50 °C for 4 h, and filtered through a 0.2 μm polytetrafluoroethylene membrane to obtain the photoresist composition.

[0082] Resin C has the following structure and can be prepared by referring to the preparation method in Example 2 of Patent CN110183654B.

[0083]

[0084] Resin D has the following structure and can be prepared by referring to the method in Example 2 of Patent CN107722265A.

[0085]

[0086] The photosensitizer is 2,2',4,4'-tetrahydroxybenzophenone-1,2-diazonaphthoquinone-5-sulfonate (average esterification degree 60%); the silicone leveling agent A is polymethylphenylsiloxane (weight-average molecular weight 3000 - 6000), the silicone leveling agent B is polydimethylsiloxane (weight-average molecular weight 5000 - 8000), and the organic solvent PGMEA is propylene glycol monomethyl ether acetate.

[0087] Table 1

[0088]

[0089]

[0090]

[0091] Effect Examples

[0092] The photoresist compositions obtained in the examples and comparative examples were respectively spin-coated on silicon wafers. Then, after vacuum drying the silicon wafers coated with the photoresist compositions, they were baked at 100 °C for 60 s to obtain a photoresist layer with a thickness of 0.75 μm.

[0093] A standard L / S = 1:1 mask plate was used for detection. The obtained photoresist layers were exposed using a light source of i-line (wavelength 365 nm), and then developed using a 2.38 wt% aqueous solution of tetramethylammonium hydroxide as the developer for 60 s to obtain photoresist patterns.

[0094] 1. Photosensitivity

[0095] It is represented by the minimum exposure dose to obtain a 0.5 μm 1:1 equal-space pattern.

[0096] 2. Resolution

[0097] Find the minimum line width, cut a slice for SEM testing, and determine its size, which is the resolution.

[0098] 3. Line Edge Roughness

[0099] Observation was carried out with an electron microscope according to the following criteria: A (excellent) - the edge of the line is a straight line and the edge is narrow; B (poor) - the edge of the line is not a single line, has a width, and the edge is wide.

[0100] Table 2

[0101]

[0102]

[0103] As can be seen from Table 2 above, the photoresist pattern formed by the photoresist composition of the present invention has good photosensitivity, and the minimum exposure dose for its 0.5 μm 1:1 equal-space pattern is between 20 - 55 (0.5 μmL / S (mJ / cm 2 ))), has high resolution, is between 0.23 - 0.53 μm, the edge of the line is a straight line, and the edge is narrow.

[0104] From the comparison of the evaluation indicators of the resolution, it can be seen that: compared with the comparative example, the resolution of the photoresist pattern formed by the photoresist composition of the present invention is high. The same applies to photosensitivity and line edge roughness. It can be seen that the photoresist composition within the scope of the present invention has good performance.

Claims

1. An i-line photoresist composition, characterized in that, It comprises the following components: resin, photosensitizer, silicone leveling agent and organic solvent; The resin comprises the following components in parts by weight: 80 - 90 parts of phenolic resin, 20 - 50 parts of resin C and 10 - 15 parts of resin D; The phenolic resin is at least one of phenolic resin A and phenolic resin B; The preparation method of the phenolic resin A comprises the following steps: reacting m-cresol, p-cresol, 3,5-xylenol and formaldehyde under the action of oxalic acid; The preparation method of the phenolic resin B comprises the following steps: reacting m-cresol, p-cresol and formaldehyde under the action of oxalic acid; The structures of the resin C and resin D are as follows: The silicone leveling agent is polymethylphenylsiloxane.

2. The i-line photoresist composition according to claim 1, wherein, The phenolic resin is 80 parts by weight; and / or, the resin C is 30 parts by weight; and / or, the resin D is 10 parts by weight; and / or, the photosensitizer is 10 - 40 parts by weight; and / or, the concentration of the silicone leveling agent in the i-line photoresist composition is 500 - 2000 ppm; and / or, the organic solvent is 450 - 800 parts by weight.

3. The i-line photoresist composition according to claim 1, wherein, The weight-average molecular weight of the silicone leveling agent is 3000 - 6000; and / or, the phenolic resin is phenolic resin A, phenolic resin B or a combination of phenolic resin A and phenolic resin B; and / or, the photosensitizer is 2,2',4,4'-tetrahydroxybenzophenone-1,2-diazonaphthoquinone-5-sulfonate; and / or, the average esterification degree of the photosensitizer is 60%; and / or, the organic solvent is one or more of ether solvents, ester solvents, amide solvents, aromatic hydrocarbon solvents and ketone solvents.

4. The i-line photoresist composition according to claim 3, characterized in that, When the phenolic resin is a combination of phenolic resin A and B, the mass ratio of phenolic resin A to phenolic resin B is 2:7 - 7:

2.

5. The i-line photoresist composition according to claim 4, wherein, The ether solvent is one or more of ethylene glycol monomethyl ether, anisole, propylene glycol monoethyl ether, diethylene glycol methyl ether and diethylene glycol ethyl ether; and / or, the ester solvent is one or more of propylene glycol monomethyl ether acetate, butyl acetate, ethyl acetate, ethyl lactate and γ-butyrolactone; and / or, the amide solvent is dimethylacetamide; and / or, the aromatic hydrocarbon solvent is xylene; and / or, the ketone solvent is N-methylpyrrolidone.

6. The i-line photoresist composition according to claim 1, wherein, In the preparation method of the phenolic resin A, the m-cresol is 30 - 80 parts by weight; and / or, in the preparation method of the phenolic resin A, the p-cresol is 20 - 50 parts by weight; and / or, in the preparation method of the phenolic resin A, the 3,5-xylenol is 1 - 10 parts by weight; and / or, in the preparation method of the phenolic resin A, the oxalic acid is 1 - 10 parts by weight; And / or, in the preparation method of phenolic resin A, formaldehyde participates in the preparation of phenolic resin A in the form of formalin solution; the mass concentration of the formalin solution is 36.9%; the formalin solution is 20 - 80 parts by weight; And / or, the preparation method of phenolic resin A is carried out in a nitrogen atmosphere; And / or, in the preparation method of phenolic resin A, the following steps are included: mixing m-cresol, p-cresol, 3,5-xylenol, formaldehyde, and oxalic acid for reaction, and adding oxalic acid once in the middle; And / or, in the preparation method of phenolic resin A, the reaction temperature is 40 - 100 °C; And / or, in the preparation method of phenolic resin A, the reaction time is 4 - 10 hours.

7. The i-line photoresist composition according to claim 6, wherein In the preparation method of phenolic resin A, m-cresol is 65 parts by weight; And / or, in the preparation method of phenolic resin A, p-cresol is 35 parts by weight; And / or, in the preparation method of phenolic resin A, 3,5-xylenol is 5 parts by weight; And / or, in the preparation method of phenolic resin A, oxalic acid is 2 parts by weight; And / or, in the preparation method of phenolic resin A, the formalin solution is 60 parts by weight; And / or, in the preparation method of phenolic resin A, the reaction temperature is 40 °C, 60 °C or 100 °C; And / or, in the preparation method of phenolic resin A, the reaction time is 7 hours.

8. The i-line photoresist composition according to claim 1, wherein In the preparation method of phenolic resin B, m-cresol is 30 - 80 parts by weight; And / or, in the preparation method of phenolic resin B, p-cresol is 20 - 50 parts by weight; And / or, in the preparation method of phenolic resin B, oxalic acid is 1 - 10 parts by weight; And / or, in the preparation method of phenolic resin B, formaldehyde participates in the reaction in the form of formalin solution; the concentration of the formalin solution is 36.9 wt%; the formalin solution is 20 - 80 parts by weight; And / or, the preparation method of phenolic resin B is carried out in a nitrogen atmosphere; And / or, in the preparation method of phenolic resin B, the following steps are included: mixing m-cresol, p-cresol, formaldehyde, and oxalic acid for reaction, and adding oxalic acid once in the middle; And / or, in the preparation method of phenolic resin B, the reaction temperature is 40 - 100 °C; And / or, in the preparation method of phenolic resin B, the reaction time is 4 - 10 hours.

9. The i-line photoresist composition according to claim 8, wherein In the preparation method of phenolic resin B, m-cresol is 55 parts by weight; And / or, in the preparation method of phenolic resin B, p-cresol is 45 parts by weight; And / or, in the preparation method of phenolic resin B, oxalic acid is 2 parts by weight; And / or, in the preparation method of the phenolic resin B, the formalin solution is 60 parts by weight; And / or, in the preparation method of the phenolic resin B, the reaction temperature is 40 °C, 60 °C or 100 °C; And / or, in the preparation method of the phenolic resin B, the reaction time is 7 hours.

10. The i-line photoresist composition according to any one of claims 1-9, wherein The resin is composed of 80-90 parts of phenolic resin, 20-50 parts of resin C and 10-15 parts of resin D, wherein the phenolic resin is at least one of phenolic resin A and phenolic resin B; Alternatively, the i-line photoresist composition is composed of the resin, the photosensitizer, the organosilicon leveling agent and the organic solvent.

11. A method for forming an i-line photoresist pattern, the method comprising the following steps: Step 1: Coating the i-line photoresist composition according to any one of claims 1-10 on the surface of a substrate, and then drying and baking to obtain a photoresist layer; Step 2: Exposing and developing the photoresist layer obtained in Step 1 to obtain a photoresist pattern.

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