I-line photoresist and its preparation method and application

Abstract

The present invention discloses an i-line photoresist, its preparation method, and application. The preparation method of the i-line photoresist composition disclosed herein comprises the following steps: uniformly mixing the components of the i-line photoresist composition; the i-line photoresist composition comprises the following components: a resin, a photosensitizer, an organosilicon leveling agent, and an organic solvent; the resin comprises the following components in parts by weight: 80-90 parts of a phenolic resin, 20-50 parts of a resin C, and 10-15 parts of a resin D; the phenolic resin is at least one of phenolic resin A and phenolic resin B. The i-line photoresist composition of the present invention, when used for i-line photolithography, produces a photoresist pattern with high photosensitivity and resolution.

Description

Technical Field

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

[0002] Photoresist is a type of etch-resistant thin film material whose solubility changes after exposure to energy sources such as light, electron, or ion beams. It is widely used in the microfabrication of integrated circuits and discrete semiconductor devices. By coating photoresist onto semiconductors, conductors, and insulators, the remaining portion after exposure and development protects the underlying layer. Etching with an etchant then allows the desired fine pattern to be transferred from the mask to the substrate being processed. Therefore, photoresist is a key material in microfabrication technology. Based on their photochemical reaction mechanisms, photoresists are categorized as positive-working and negative-working. After exposure, the solubility of the photoresist in the developer increases, resulting in a pattern identical to that of the mask. Negative-working photoresists, however, decrease in solubility or even insolubility in the developer, resulting in a pattern opposite to that of the mask. Both types of photoresist have distinct applications. Generally speaking, positive-working photoresists are more commonly used, accounting for over 80% of all photoresists.

[0003] As integrated circuits increase in density and process linewidths shrink, photolithography technology has evolved from g-line (436nm) lithography to i-line (365nm) lithography, deep ultraviolet (248nm) lithography, and the current 193nm lithography. Photoresists corresponding to these exposure wavelengths have also been developed. As exposure wavelengths change, the composition and structure of photoresists have also evolved to ensure their overall performance meets the requirements of the corresponding integrated process. However, the photosensitivity and resolution of i-line lithography currently require improvement. Summary of the Invention

[0004] The present invention aims to overcome the shortcomings of existing i-line lithography, such as poor photosensitivity and low resolution, in photoresist patterns produced by conventional i-line lithography. The present invention provides an i-line photoresist, a preparation method, and applications thereof. The i-line photoresist composition of the present invention, when used in i-line lithography, produces photoresist patterns with high photosensitivity and resolution.

[0005] The present invention provides an i-line photoresist composition, which comprises the following components: a resin, a photosensitizer, an organosilicon leveling agent and an 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 comprises the following steps: reacting m-cresol, p-cresol, 3,5-dimethylphenol and formaldehyde under the action of oxalic acid to obtain;

[0009] 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 to obtain;

[0010] The structures of the resin C and resin D are shown below:

[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 resins A and B, the mass ratio of phenolic resin A to phenolic resin B is preferably 2:7-7:2 (e.g., 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 consists 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 used in conventional parts in the art in terms of weight, 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 may be a 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 may be in a conventional amount in the art in terms of parts by weight, preferably 450-800 parts, for example 450 parts.

[0024] In the present invention, the weight average molecular weight of the organosilicon leveling agent is preferably 3000-6000.

[0025] In the present invention, the photosensitizer may be a conventional photosensitizer in the art, preferably 2,2',4,4'-tetrahydroxybenzophenone-1,2-diazonaphthoquinone-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 (e.g., one or two) of an ether solvent, an ester solvent, an amide solvent, an aromatic hydrocarbon solvent, and a ketone solvent. The ether solvent can be one or more of ethylene glycol monomethyl ether, anisole, propylene glycol monoethyl ether, diethylene glycol methyl ether, and diethylene glycol ethyl 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 two solvents are used, the weight ratio of the first solvent to the second solvent is not specifically limited, preferably 1:1-1:2, for example, 1:1.25.

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

[0029] In a certain embodiment, the organic solvent is preferably an ether solvent (the first solvent) and an amide solvent (the second solvent).

[0030] In the preparation method of the phenolic resin A, the amount of m-cresol in parts by weight can be conventional 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 in parts by weight can be conventional 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-dimethylphenol in parts by weight can be conventional in the art, preferably 2-15 parts, such as 5 parts.

[0033] In the preparation method of the phenolic resin A, the amount of oxalic acid in parts by weight can be conventional in the art, preferably 1-5 parts, for example 2 parts.

[0034] In the preparation method of the phenolic resin A, formaldehyde is preferably added to the preparation of the phenolic resin A in the form of a formalin solution. The mass concentration of the formalin solution can be 36.9%. The formalin solution can be a conventional amount in the art, preferably 20-80 parts by weight, for example 60 parts.

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

[0036] The method for preparing phenolic resin A preferably includes the following steps: mixing m-cresol, p-cresol, 3,5-xylenol, formaldehyde, and oxalic acid for reaction, and adding oxalic acid once during the reaction. When adding oxalic acid once during the reaction, the amount of oxalic acid added in the first and second additions is the same, and the amount of oxalic acid used in both additions is 2 parts by weight.

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

[0038] In the preparation method of the phenolic resin A, the reaction time may be a conventional reaction time in the art, preferably 4-10 hours, for example 7 hours.

[0039] The preparation method of the phenolic resin A preferably includes the following steps: mixing m-cresol, p-cresol, 3,5-dimethylphenol, 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] The preparation method of the phenolic resin A may further include a distillation step to remove water and unreacted monomers.

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

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

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

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

[0045] In the preparation method of the phenolic resin B, formaldehyde is preferably added to 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 a conventional amount in the art, preferably 30-80 parts by weight, for example 60 parts.

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

[0047] The method for preparing phenolic resin B preferably includes the following steps: mixing m-cresol, p-cresol, 3,5-xylenol, formaldehyde, and oxalic acid for reaction, and adding oxalic acid once during the reaction. When the oxalic acid is added once during the reaction, the amount of oxalic acid added in the first and second additions is the same, and the amount of oxalic acid used in both additions is 2 parts by weight.

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

[0049] In the preparation method of the phenolic resin B, the reaction time may be a conventional reaction time in the art, preferably 4-10 hours, for example 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] The preparation method of the phenolic resin B may further include a distillation step to remove water and unreacted monomers.

[0052] In one 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 consists of the resin, the photosensitizer, the organosilicon leveling agent and the organic solvent.

[0054] The present invention also provides a method for preparing an i-line photoresist composition, which comprises the following steps: uniformly mixing the above components.

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

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

[0057] In the 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 be further included. The filtration method may be conventional, preferably 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, the method comprising the following steps:

[0060] Step 1: coating the above-mentioned photoresist composition on the surface of the substrate, and then drying and baking 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 may be a conventional substrate in the art, preferably a silicon wafer.

[0063] In step 1, the coating method may 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 may 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. The present invention preferably uses a standard L / S=1:1 to detect the mask and uses an i-line light source (i-line wavelength 365nm) to expose the obtained photoresist layer.

[0069] In step 2, the development can be a conventional operation in the art, and a developer generally used is a tetramethylammonium hydroxide (TMAH) aqueous solution, for example, a TMAH aqueous solution with a mass fraction of 2.38%.

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

[0071] Without violating the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain preferred embodiments of the present invention.

[0072] The resin of the present invention is homemade, and other reagents and raw materials used are commercially available.

[0073] The positive progress of the present invention is that the photoresist pattern formed by the photoresist composition of the present invention has good photosensitivity, and the minimum exposure of the 0.5μm 1:1 equal-space pattern is 20-55 (0.5μmL / S (mJ / cm 2 )), the resolution is high, at 0.21-0.55 μm, the line edge is a straight line, and the edge is narrow. Therefore, the photoresist composition of the present invention has good performance. DETAILED DESCRIPTION

[0074] The present invention is further illustrated by way of examples below, but the present invention is not limited to the scope of the examples. Experimental methods in the following examples where specific conditions are not specified were performed 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-dimethylphenol, 60 parts by weight of formalin solution (mass fraction of 36.9%) and 1 part by weight of oxalic acid were added to a reactor, heated to 40°C under nitrogen protection for reaction for 1 hour, then reacted at 60°C for 2 hours, and finally, 1 part by weight of oxalic acid was added and the temperature was raised to 100°C for reaction for 4 hours. Water and unreacted monomers were distilled off to obtain phenolic resin A.

[0077] Preparation Example 2 Preparation of phenolic resin B

[0078] The phenolic resin is 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 of 36.9%) and 1 part by weight of oxalic acid are added to a reactor, heated to 40° C. for reaction for 1 hour under nitrogen protection, then reacted at 60° C. for 2 hours, finally added with 1 part by weight of oxalic acid, heated to 100° C. for reaction for 4 hours, and distilled to remove water and unreacted monomers to obtain phenolic resin B.

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

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

[0081] According to the proportions in Table 1, 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 a photoresist composition.

[0082] The structure of resin C is as follows, and it can be prepared by referring to the preparation method in Example 2 of patent CN110183654B.

[0083]

[0084] The structure of resin D is as follows, and it can be prepared by referring to the method in Example 2 of 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]

[0092] Effect embodiment

[0093] The photoresist compositions obtained in the embodiment and the comparative example were respectively coated on a silicon wafer using a spin coater. Then, the silicon wafer coated with the photoresist composition was vacuum dried and baked at 100° C. for 60 seconds to obtain a photoresist layer with a thickness of 0.75 μm.

[0094] A standard L / S=1:1 detection mask was used, and the obtained photoresist layers were exposed using an i-line (wavelength of 365nm) light source. Then, the exposed photoresist layers were developed using a 2.38wt% tetramethylammonium hydroxide aqueous solution as a developer. The development time was 60s to obtain a photoresist pattern.

[0095] 1. Photosensitivity

[0096] It is expressed as the minimum exposure to obtain a 0.5μm 1:1 equal-space pattern.

[0097] 2. Resolution

[0098] Find the minimum line width, slice it for SEM testing, and determine its size, which is the resolution.

[0099] 3. Line edge roughness

[0100] Observation with an electron microscope was performed according to the following criteria: A (excellent)—the edge of the line was a straight line with a narrow edge; B (poor)—the edge of the line was not a straight line, had width, and had a wide edge.

[0101] Table 2

[0102]

[0103]

[0104] As shown in Table 2, the photoresist pattern formed by the photoresist composition of the present invention has good photosensitivity, and the minimum exposure dose of the 0.5 μm 1:1 equal-space pattern is between 20-55 (0.5 μmL / S (mJ / cm 2 )), the resolution is high, at 0.21-0.55μm, the line edge is a straight line, and the edge is narrow.

[0105] Comparison of the resolution evaluation index shows that the photoresist composition of the present invention produces a photoresist pattern with higher resolution than the comparative example. The same applies to photosensitivity and line edge roughness. This shows that the photoresist composition within the scope of the present invention exhibits superior performance.

Claims

1. A method for preparing an i-line photoresist composition, characterized in that: The method comprises the following steps: uniformly mixing the components of the i-line photoresist composition; The i-line photoresist composition 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, 20-25 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-dimethylphenol and formaldehyde under the action of oxalic acid to obtain; 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 to obtain; The structures of the resin C and resin D are shown below: The organosilicon leveling agent is polymethylphenylsiloxane.

2. The method for preparing the i-line photoresist composition according to claim 1, wherein The phenolic resin is 80 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 organosilicon 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 method for preparing the i-line photoresist composition according to claim 1, wherein The weight average molecular weight of the organosilicon leveling agent is 3000-6000; and / or, the photosensitizer is 2,2',4,4'-tetrahydroxybenzophenone-1,2-diazonaphthoquinone-5-sulfonate; and / or, the average degree of esterification of the photosensitizer is 60%; And / or, the organic solvent is one or more of an ether solvent, an ester solvent, an amide solvent, an aromatic hydrocarbon solvent and a ketone solvent.

4. The method for preparing the i-line photoresist composition according to claim 1, wherein When the phenolic resin is a combination of phenolic resins A and B, the mass ratio of phenolic resin A to phenolic resin B is 2:7-7:

2.

5. The method for preparing the i-line photoresist composition according to claim 3, 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 method for preparing the i-line photoresist composition according to claim 5, wherein: In the i-line photoresist composition: The ether solvent is ethylene glycol monomethyl ether; And / or, the ester solvent is propylene glycol monomethyl ether acetate.

7. The method for preparing an i-line photoresist composition according to any one of claims 1 to 6, wherein: In the preparation method of the phenolic resin A, the amount of m-cresol is 30-80 parts by weight; And / or, in the preparation method of the phenolic resin A, p-cresol is 20-50 parts by weight; And / or, in the preparation method of the phenolic resin A, 2-15 parts by weight of 3,5-dimethylphenol; And / or, in the preparation method of the phenolic resin A, the oxalic acid is 1-5 parts by weight; And / or, in the preparation method of the phenolic resin A, formaldehyde is added to the preparation of the phenolic resin A in the form of a formalin solution; the mass fraction of the formalin solution is 36.9 wt %; the formalin solution is 20-80 parts by weight; and / or, the preparation method of the phenolic resin A is carried out under a nitrogen atmosphere; And / or, the preparation method of the phenolic resin A comprises the following steps: mixing m-cresol, p-cresol, 3,5-xylenol, formaldehyde and oxalic acid to react, and adding oxalic acid once in the middle; and / or, in the preparation method of the 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.

8. The method for preparing the i-line photoresist composition according to claim 7, wherein: In the preparation method of the phenolic resin A, the amount of m-cresol is 65 parts by weight; And / or, in the preparation method of the phenolic resin A, p-cresol is 35 parts by weight; And / or, in the preparation method of the phenolic resin A, 3,5-dimethylphenol is 5 parts by weight; And / or, in the preparation method of the phenolic resin A, the amount of oxalic acid is 2 parts by weight; And / or, in the preparation method of the phenolic resin A, the formalin solution is 60 parts by weight; and / or, in the preparation method of the 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.

9. The method for preparing an i-line photoresist composition according to any one of claims 1 to 6, wherein: In the preparation method of the phenolic resin B, the amount of m-cresol is 30-80 parts by weight; And / or, in the preparation method of the phenolic resin B, p-cresol is 20-50 parts by weight; And / or, in the preparation method of the phenolic resin B, the oxalic acid is 1-10 parts by weight; And / or, in the preparation method of the phenolic resin B, formaldehyde participates in the reaction in the form of a formalin solution; the mass fraction of the formalin solution is 36.9wt%; the formalin solution is 30-80 parts by weight; and / or, the preparation method of the phenolic resin B is carried out under a nitrogen atmosphere; And / or, the preparation method of the phenolic resin B comprises the following steps: mixing m-cresol, p-cresol, formaldehyde and oxalic acid to react, and adding oxalic acid once in the middle; and / or, in the preparation method of the phenolic resin B, the reaction temperature is 40-100° C.; And / or, in the preparation method of the phenolic resin B, the reaction time is 4-10 hours.

10. The method for preparing the i-line photoresist composition according to claim 9, wherein: In the preparation method of the phenolic resin B, the amount of m-cresol is 55 parts by weight; And / or, in the preparation method of the phenolic resin B, p-cresol is 45 parts by weight; And / or, in the preparation method of the phenolic resin B, the amount of 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.

11. The method for preparing an i-line photoresist composition according to any one of claims 1 to 6, wherein: The resin is composed of 80-90 parts of phenolic resin, 20-25 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 consists of the resin, the photosensitizer, the organosilicon leveling agent and the organic solvent.

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