A photosensitizer, i-line photoresist containing the same and a preparation method thereof

Abstract

This invention discloses a photosensitizer, an i-line photoresist containing the photosensitizer, and a preparation method thereof. The photosensitizer disclosed in this invention is composed of photosensitizer A and photosensitizer B. The i-line photoresist composition prepared using the photosensitizer of this invention exhibits high photosensitivity and resolution when used in i-line lithography.

Description

Technical Field

[0001] This invention relates to a photosensitizer, an i-line photoresist containing the photosensitizer, and a preparation method thereof. Background Technology

[0002] Photoresist is a type of etch-resistant thin-film material whose solubility changes after being irradiated with energy such as light beams, electron beams, or ion beams. It has wide applications in the microfabrication of integrated circuits and discrete semiconductor devices. By coating photoresist onto semiconductor, conductor, and insulator materials, the remaining portion after exposure and development protects the underlying material. Then, etching with an etchant transfers the desired micro-pattern from the photomask to the substrate. Therefore, photoresist is a key material in microfabrication technology. Based on different photochemical reaction mechanisms, photoresists are classified into positive and negative photoresists: positive photoresists have increased solubility in the developer after exposure, resulting in a pattern identical to the photomask; negative photoresists have decreased solubility or even become insoluble in the developer, resulting in a pattern opposite to the photomask. Both types of photoresists have their own distinct applications. Generally speaking, positive photoresists are more widely used, accounting for over 80% of all photoresists.

[0003] As integrated circuit integration density increases and processing linewidths shrink, photolithography technology has evolved from g-line (436nm) lithography, to i-line (365nm) lithography, to deep ultraviolet 248nm lithography, and currently to 193nm lithography. Corresponding photoresists for each exposure wavelength have also been developed. With changes in exposure wavelength, the composition and structure of the photoresist continuously change to ensure its overall performance meets the requirements of the corresponding integrated circuit process. However, currently, phenolic resin-diazonaphthoquinone positive photoresist is used in i-line lithography, and its photosensitivity and resolution need improvement. Summary of the Invention

[0004] The technical problem to be solved by this invention is to overcome the defects of poor photosensitivity and low resolution of photoresist patterns obtained by existing i-line lithography, thereby providing a photosensitizer, an i-line photoresist containing the photosensitizer, and a preparation method thereof. The i-line photoresist composition prepared using the photosensitizer of this invention produces photoresist patterns with high photosensitivity and resolution when used in i-line lithography.

[0005] This invention provides a photosensitizer, which is composed of photosensitizer A and photosensitizer B; the structures of photosensitizer A and photosensitizer B are shown below:

[0006]

[0007] In this invention, the photosensitizer A can be 10-20 parts by weight, such as 10-17 parts or 10-15 parts.

[0008] In this invention, the photosensitizer B can be 5-10 parts by weight, such as 5 parts.

[0009] The present invention also provides an i-line photoresist composition comprising the following components: phenolic resin, the photosensitizer, an organosilicon leveling agent, and an organic solvent;

[0010] The phenolic resin is at least one of phenolic resin A and phenolic resin B;

[0011] 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 the resin A.

[0012] 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 the resin;

[0013] The organosilicon leveling agent may be polymethylphenylsiloxane.

[0014] In this invention, the phenolic resin may be 80-100 parts by weight, for example 80 parts.

[0015] In this invention, the phenolic resin may be phenolic resin A.

[0016] In this invention, the phenolic resin may be phenolic resin B.

[0017] In this invention, the phenolic resin may be a combination of phenolic resin A and phenolic resin B. When the phenolic resin is a combination of phenolic resin A and phenolic resin 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 this invention, the weight-average molecular weight of the silicone leveling agent is preferably 3000-6000. The concentration of the silicone leveling agent in the i-line photoresist composition can be a concentration conventional in the art, preferably 500-2000 ppm, for example 500 ppm, 1000 ppm or 2000 ppm.

[0019] In this invention, the organic solvent, by weight, can be a conventional amount in the art, preferably 450-800 parts, for example 450 parts. The organic solvent can be a variety of conventional solvents in the art, preferably one or more (e.g., one or two) of ether solvents, ester solvents, amide solvents, aromatic solvents, and ketone solvents. The ether solvent can be one or more of ethylene glycol monomethyl ether, propylene glycol methyl 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 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.

[0020] In one embodiment, the organic solvent is preferably one of an ether solvent, an ester solvent, an amide solvent, an aromatic solvent, or a ketone solvent.

[0021] In one embodiment, the organic solvent is preferably either an ether solvent (the first type of solvent) or an amide solvent (the second type of solvent).

[0022] 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 50-80 parts, for example 65 parts.

[0023] 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, for example 35 parts.

[0024] In the preparation method of the phenolic resin A, the 3,5-xylenol can be in the conventional amount by weight, preferably 1-10 parts, for example 5 parts.

[0025] In the preparation method of the phenolic resin A, the oxalic acid can be in the conventional amount in the art, preferably 0.5-5 parts by weight, for example 2 parts.

[0026] In the preparation method of the phenolic resin A, formaldehyde is preferably incorporated into 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 in conventional parts by weight, preferably 20-80 parts, for example 60 parts.

[0027] The preparation method of the phenolic resin A can be carried out under a nitrogen atmosphere.

[0028] The preferred method for preparing the phenolic resin A includes the following steps: mixing m-cresol, p-cresol, 3,5-xylenol, formaldehyde, and oxalic acid and reacting them, with oxalic acid added once during the reaction. When adding oxalic acid once during the reaction, the amount of oxalic acid added the first time and the second time is the same. The total amount of oxalic acid used in both reactions is 2 parts by weight.

[0029] In the preparation method of the phenolic resin A, the reaction temperature can be a conventional reaction temperature in the art, preferably 40-100℃, for example 40℃, 60℃ or 100℃.

[0030] In the preparation method of the phenolic resin A, the reaction time can be a conventional reaction time in the art, preferably 4-10 hours, for example 7 hours.

[0031] The preferred method for preparing the phenolic resin A includes the following steps: mixing m-cresol, p-cresol, 3,5-xylenol, formalin solution and oxalic acid, reacting at 40°C for 1 hour, reacting at 60°C for 2 hours, and finally adding oxalic acid and reacting at 100°C for 4 hours.

[0032] The preparation method of the phenolic resin A may further include a distillation step to remove water and unreacted monomers.

[0033] In one embodiment, the preparation method of the phenolic resin A is as shown in Preparation Example 1.

[0034] In the preparation method of the phenolic resin B, the amount of m-cresol by weight can be a conventional amount in the art, preferably 35-60 parts, for example 55 parts.

[0035] In the preparation method of the phenolic resin B, the amount of p-cresol by weight can be a conventional amount in the art, preferably 35-55 parts, for example 45 parts.

[0036] In the preparation method of the phenolic resin B, the oxalic acid can be in the conventional amount in the art, preferably 0.5-8 parts by weight, for example 2 parts.

[0037] In the preparation method of the phenolic resin B, formaldehyde is preferably incorporated into 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 conventional parts by weight, preferably 30-80 parts, for example 60 parts.

[0038] The preparation method of the phenolic resin B can be carried out under a nitrogen atmosphere.

[0039] The preferred method for preparing the phenolic resin B includes the following steps: mixing m-cresol, p-cresol, 3,5-xylenol, formaldehyde, and oxalic acid and reacting them, with oxalic acid added once during the reaction. When adding oxalic acid once during the reaction, the amount of oxalic acid added the first time and the second time is the same. The total amount of oxalic acid used in both reactions is 2 parts by weight.

[0040] In the preparation method of the phenolic resin B, the reaction temperature can be a conventional reaction temperature in the art, preferably 40-100℃, for example 40℃, 60℃ or 100℃.

[0041] In the preparation method of the phenolic resin B, the reaction time can be a conventional reaction time in the art, preferably 4-10 hours, for example 7 hours.

[0042] The preferred method for preparing the phenolic resin B includes the following steps: mixing m-cresol, p-cresol, formalin solution and oxalic acid and 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.

[0043] The preparation method of the phenolic resin B may further include a distillation step to remove water and unreacted monomers.

[0044] In one embodiment, the preparation method of the phenolic resin B is as shown in Preparation Example 2.

[0045] In one embodiment, the i-line photoresist composition comprises the resin, the photosensitizer, the silicone leveling agent, and the organic solvent.

[0046] The present invention also provides a method for preparing an i-line photoresist composition, which includes the following steps: mixing the above components evenly.

[0047] In the preparation method described above, the mixing method can be a conventional mixing method in the art, preferably stirring.

[0048] In the preparation method described above, the mixing temperature can be a conventional mixing temperature in the art, preferably 50°C.

[0049] In the preparation method described above, the mixing time can be a conventional mixing time in the art, preferably 4 hours.

[0050] The mixture may further include a filtration step. The filtration method can be a conventional method, preferably using a polytetrafluoroethylene (PTFE) membrane. The PTFE membrane preferably has a pore size of 0.2 μm.

[0051] The present invention also provides a method for forming i-line photoresist patterns, the method comprising the following steps:

[0052] Step 1: Coat the above photoresist composition onto the substrate surface, then dry and bake to obtain a photoresist layer;

[0053] Step 2: Expose and develop the photoresist layer obtained in Step 1 to obtain the photoresist pattern.

[0054] In step 1, the substrate can be a conventional substrate in the art, preferably a silicon wafer.

[0055] In step 1, the coating method can be a conventional method in the art, preferably a spin coater.

[0056] In step 1, the thickness of the photoresist layer can be a conventional thickness in the art, preferably 0.75 μm.

[0057] In step 1, the drying can be conventional drying in the art, preferably vacuum drying.

[0058] In step 1, the baking temperature can be a conventional baking temperature in the art, preferably 100°C.

[0059] In step 1, the baking time is preferably 60 seconds.

[0060] In step 2, the exposure can be a conventional operation in the field. In this invention, the photomask is preferably inspected using a standard L / S = 1:1 ratio, and the obtained photoresist layer is exposed using an i-line light source (i-line wavelength 365nm).

[0061] In step 2, the development can be a conventional operation in the art, and the developer generally used is an aqueous solution of tetramethylammonium hydroxide (TMAH), such as a 2.38% TMAH aqueous solution by mass.

[0062] In step 2, the development time is preferably 60 seconds.

[0063] Without violating common sense in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0064] The resin used in this invention is self-made, while all other reagents and raw materials used are commercially available.

[0065] The positive and progressive effects of this invention are that the film formed using the i-line photoresist composition of this invention has the advantages of excellent photosensitivity and high resolution. Detailed Implementation

[0066] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0067] Preparation Example 1: Preparation of Phenolic Resin A

[0068] 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 vessel and heated to 40°C for 1 hour under nitrogen protection, then reacted at 60°C for 2 hours. Finally, 1 part by weight of oxalic acid was added and the temperature was raised to 100°C for 4 hours. Water and unreacted monomers were removed by distillation to obtain phenolic resin A.

[0069] Preparation Example 2: Preparation of Phenolic Resin B

[0070] 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 reaction vessel, heated to 40°C for 1 hour under nitrogen protection, then reacted at 60°C for 2 hours, and finally 1 part by weight of oxalic acid is added and the temperature is raised to 100°C for 4 hours. Water and unreacted monomers are removed by distillation to obtain phenolic resin B.

[0071] In the following examples or comparative examples, the photoresist compositions were prepared according to the following method:

[0072] Examples 1-26 and Comparative Examples 1-11

[0073] According to the proportions in Table 1, phenolic resin, photosensitizer, silicone leveling agent and organic solvent were mixed, stirred at 50°C for 4 hours, and filtered through a 0.2 μm polytetrafluoroethylene membrane to obtain a photoresist composition.

[0074] The structures of photosensitizer A and photosensitizer B are shown below:

[0075]

[0076] Photosensitizer C is 2,2',4,4'-tetrahydroxybenzophenone-1,2-diazonaphthoquinone-5-sulfonate, silicone leveling agent A is polymethylphenylsiloxane (weight average molecular weight 3000-6000), silicone leveling agent B is polydimethylsiloxane (weight average molecular weight 5000-8000), and organic solvent PGMEA is propylene glycol monomethyl ether acetate.

[0077] All components are expressed in parts by weight.

[0078] Table 1

[0079]

[0080]

[0081] Effect Example

[0082] The photoresist compositions obtained in the examples and comparative examples were coated onto silicon wafers using a spin coater. Then, the silicon wafers coated with the photoresist compositions were vacuum dried and baked at 100°C for 60 seconds to obtain a photoresist layer with a thickness of 0.75 μm.

[0083] A standard L / S = 1:1 detection mask was used, and the obtained photoresist layers were exposed using an i-line light source (wavelength of 365nm). Then, the exposed photoresist layers were developed using a 2.38wt% tetramethylammonium hydroxide solution for 60s to obtain the photoresist pattern.

[0084] 1. Photosensitivity

[0085] It is expressed as the minimum exposure required to obtain a 0.5μm 1:1 isotropic pattern.

[0086] 2. Resolution

[0087] Find the minimum linewidth, slice it, perform SEM testing, and determine its size, which is the resolution.

[0088] 3. Roughness of line edges

[0089] Observe 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 straight line and has width and the edge is wide; C (Very Poor) - The edge of the line is blurred into an arc shape.

[0090] Table 2

[0091]

[0092]

[0093] As shown in Table 2 above, the photoresist composition of the present invention forms photoresist patterns with good photosensitivity, and the minimum exposure of its 0.5μm 1:1 isotropic patterns is 20-55 (0.5μmL / S (mJ / cm²)). 2 The resolution is high, between 0.24 and 0.55 μm, and the lines have a straight edge with narrow edges.

[0094] The comparison of resolution evaluation metrics shows that, compared to the comparative example, the photoresist composition of the present invention forms a photoresist pattern with higher resolution. The same applies to photosensitivity and line edge roughness. Therefore, the photoresist composition within the scope of the present invention exhibits superior performance.

Claims

1. An i-line photoresist composition, comprising the following components: Phenolic resin, photosensitizer, silicone leveling agent, and organic solvent; The phenolic resin is at least one of phenolic resin A and phenolic resin B; 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 the resin A. 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 the resin; The organosilicon leveling agent is polymethylphenylsiloxane; The photosensitizer is composed of photosensitizer A and photosensitizer B; the structures of photosensitizer A and photosensitizer B are shown below: ； Photosensitizer A; Photosensitizer B; The photosensitizer A is 10-20 parts by weight; The photosensitizer B is 5-10 parts by weight.

2. The i-line photoresist composition as described in claim 1, characterized in that, The phenolic resin is 80-100 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; And / or, the photosensitizer A is 10-17 parts or 10-15 parts by weight; And / or, the photosensitizer B is 5 parts by weight.

3. The i-line photoresist composition as described in claim 2, characterized in that, The phenolic resin is 80 parts by weight; And / or, the concentration of the silicone leveling agent in the i-line photoresist composition is 500 ppm, 1000 ppm or 2000 ppm; And / or, the organic solvent is 450 parts by weight.

4. The i-line photoresist composition as described in claim 1, characterized in that, The phenolic resin is phenolic resin A, phenolic resin B, or 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 2:7-7:

2. And / or, the weight-average molecular weight of the silicone leveling agent is 3000-6000; And / or, the organic solvent is one or more of ether solvents, ester solvents, amide solvents, aromatic solvents and ketone solvents.

5. The i-line photoresist composition as described in claim 4, characterized in that, The ether solvent is one or more of ethylene glycol monomethyl ether, propylene glycol methyl 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 solvent is xylene; And / or, the ketone solvent is N-methylpyrrolidone.

6. The i-line photoresist composition according to any one of claims 1-5, characterized in that, In the preparation method of the phenolic resin A, m-cresol is 50-80 parts by weight; And / or, in the method for preparing phenolic resin A, p-cresol is 20-50 parts by weight; And / or, in the method for preparing phenolic resin A, 3,5-xylenol is 1-10 parts by weight; And / or, in the method for preparing phenolic resin A, oxalic acid is 0.5-5 parts by weight; And / or, in the method for preparing phenolic resin A, formaldehyde is involved 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 the phenolic resin A is carried out under a nitrogen atmosphere; And / or, the preparation method of the phenolic resin A includes the following steps: mixing m-cresol, p-cresol, 3,5-xylenol, formaldehyde, and oxalic acid and reacting them, with oxalic acid added once in the middle; And / or, in the preparation method of the phenolic resin A, the reaction temperature is 40-100℃; And / or, in the method for preparing phenolic resin A, the reaction time is 4-10 hours; And / or, in the method for preparing phenolic resin B, m-cresol is 35-60 parts by weight; And / or, in the method for preparing phenolic resin B, p-cresol is 35-55 parts by weight; And / or, in the method for preparing phenolic resin B, oxalic acid is 0.5-8 parts by weight; And / or, in the method for preparing phenolic resin B, formaldehyde is involved in the preparation of phenolic resin B in the form of formalin solution; the concentration of the formalin solution is 36.9 wt%; 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 includes the following steps: mixing m-cresol, p-cresol, formaldehyde, and oxalic acid to react, with oxalic acid added once in the middle; when oxalic acid is added once in the middle, the amount of oxalic acid added the first time and the second time is the same; And / or, in the preparation method of the phenolic resin B, the reaction temperature is 40-100℃; And / or, in the method for preparing phenolic resin B, the reaction time is 4-10 hours.

7. The i-line photoresist composition as described in claim 6, characterized in that, In the preparation method of the phenolic resin A, m-cresol is 65 parts by weight; And / or, in the method for preparing phenolic resin A, p-cresol is 35 parts by weight; And / or, in the method for preparing phenolic resin A, 3,5-xylenol is 5 parts by weight; And / or, in the method for preparing phenolic resin A, oxalic acid is 2 parts by weight; In the preparation method of the phenolic resin A, formaldehyde is involved in the preparation of the phenolic resin A in the form of formalin solution; the mass concentration of the formalin solution is 36.9%; and the formalin solution is 60 parts by weight. And / or, in the method for preparing phenolic resin A, the reaction temperature is 40°C, 60°C or 100°C; And / or, in the method for preparing phenolic resin A, the reaction time is 7 hours; And / or, in the method for preparing phenolic resin B, m-cresol is 55 parts by weight; And / or, in the method for preparing phenolic resin B, p-cresol is 45 parts by weight; And / or, in the method for preparing phenolic resin B, oxalic acid is 2 parts by weight; And / or, in the method for preparing phenolic resin B, formaldehyde is involved in the preparation of phenolic resin B in the form of formalin solution; the concentration of the formalin solution is 36.9 wt%; the formalin solution is 60 parts by weight. And / or, in the method for preparing phenolic resin B, the reaction temperature is 40°C, 60°C, or 100°C; And / or, in the method for preparing phenolic resin B, the reaction time is 7 hours.

8. The i-line photoresist composition as described in claim 6, characterized in that, The preparation method of the phenolic resin A includes the following steps: mixing m-cresol, p-cresol, 3,5-xylenol, formalin solution and oxalic acid, reacting at 40°C for 1 hour, reacting at 60°C for 2 hours, and finally adding oxalic acid and reacting at 100°C for 4 hours. And / or, the preparation method of the phenolic resin B includes the following steps: mixing m-cresol, p-cresol, formalin solution and oxalic acid and 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.

9. A method for forming an i-line photoresist pattern, characterized in that, The method includes the following steps: Step 1: Coat the photoresist composition as described in any one of claims 1-8 onto the surface of a substrate, then dry and bake to obtain a photoresist layer; Step 2: Expose and develop the photoresist layer obtained in Step 1 to obtain the photoresist pattern.

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