Thick film photoresist developer composition for integrated circuits

Abstract

The present invention discloses a thick-film photoresist developer composition for integrated circuits, belonging to the field of wet electronic chemicals. The composition comprises, by weight percentage, 0.1-5% inorganic base, 0.1-5% development enhancer, 0.1-5% stabilizer, 0.1-2% surfactant, with the balance being water. The surfactant has a chemical formula of (n=1-15, p, e=1-6) and has excellent developing performance, ensuring a guaranteed developing rate, uniformity of developing performance during the developing process, and precision of the developed pattern. Furthermore, the developer improves the dispersibility of the developer in the photoresist, avoiding the occurrence of photoresist residue. The resulting developer composition has low foaming, is easy to rinse, has good wettability, does not leave residue on the chip, is environmentally friendly, and is suitable for developing thick-film photoresists used in integrated circuit chip manufacturing and packaging processes.

Description

Technical Field

[0001] The invention belongs to the field of wet electronic chemicals, and in particular relates to a thick film photoresist developer composition used in the process of integrated circuit chip processing and packaging. Background Art

[0002] Photoresist is a pattern transfer medium that transfers the mask pattern to the substrate by utilizing different solubility levels after exposure to light. It is a core material in photolithography technology used in semiconductor manufacturing. Photoresist primarily consists of a sensitizer (photoinitiator), a polymerizer (photosensitive resin), a solvent, and additives. Based on the wavelength of the light source, it can be categorized into broad-spectrum ultraviolet (300-450nm), g-line (436nm), i-line (365nm), KrF (248nm), ArF (193nm), and EUV (13.5nm). Each type of photoresist has distinct components and is suitable for different IC process nodes. Depending on whether the exposed areas are removed or retained during the development process, it is further divided into positive-tone photoresist (positive photoresist) and negative-tone photoresist (negative photoresist). After exposure, the solubility of positive-tone photoresist increases during the subsequent development process, making it easily soluble in the developer, while the non-exposed areas remain insoluble. In contrast, the non-exposed areas of negative-tone photoresist are readily soluble in the developer.

[0003] The minimum pattern or pitch that can be produced in a photoresist layer is often used as a reference for photoresist resolution. The most critical device and circuit dimensions (CD) on the wafer are the target of the patterning process. Smaller patterns or pitches indicate higher resolution. Photoresist resolution is actually the resolution of a specific process, which includes the exposure source and development process. Changing process parameters can alter the inherent resolution of the photoresist. Generally speaking, finer line widths require thinner photoresist films. However, the photoresist must be thick enough to achieve resistive etching and be pinhole-free. For example, in a heterojunction bipolar transistor structure, openings are required above the emitter, base, and collector contact metals, where the trace metal is deposited. This requires a thicker photoresist to facilitate metal deposition. In chip packaging, high-thickness photoresists, due to their unique design, have strict film thickness requirements, coating uniformity within 10%, profile angles within 88-90°, and resistance to copper electroplating.

[0004] With the continuous development of chip technology, the thickness of photoresist continues to increase, reaching a maximum of about 100 microns. Traditional developers have excellent development effects on photoresists with a thickness of about 1 micron, but when used for thicker photoresist layers, problems such as uneven development, inability to disperse photoresist, slow development speed, and line width that does not meet requirements may easily occur during the development process.

[0005] Patent CN 101872136A discloses a developer for flat panel displays, which is composed of a nonionic surfactant and an alkaline compound. The line width of the developed object is relatively large. For developers used in integrated circuits, the line width requirement is much less than 5μm, which cannot meet the development requirements and causes the development to stop. Patent CN 105589303A discloses a high-capacity developer composition for thick-film photoresists, which is composed of 1% to 10% KOH or Na2SiO3, 1% to 4% potassium metaborate as a development buffer, 0.1% to 2% DGME as a development accelerator, 0.01% to 0.05% SF-440 as an acetylene glycol surfactant, and DF-62 as an ether-modified silicone defoamer. The developer comprises 0.005% to 1% of a developing agent, and the addition of a developing accelerator is a heterocyclic water-soluble organic solvent such as alcohol ether, sulfoxide, or pyrrole, which can ensure the developing capacity and enhance the developing speed, but has a certain solubility for the photosensitive resin, resulting in uneven development. Patent CN105589304A discloses a developer for positive photoresist and its application. The developer comprises an alkali source, a wetting dispersant, a metal protective agent, water, and a development enhancer. The development enhancer is one or a combination of two selected from boric acid and a C2 to C4 hydroxy acid. The molar ratio of the alkali source to the development enhancer is 1:(0.05 to 0.2). Rapid development can be achieved by adjusting the concentration of hydroxide in the developer. However, for thick film photoresist, as the thickness of the photoresist increases, the migration speed of the reaction product into the developer slows down after the reaction between the photosensitive resin and hydroxide, resulting in insufficient development. Summary of the Invention

[0006] In order to overcome the problems of uneven development, insufficient development, slow development rate, poor development pattern accuracy, etc. in existing semiconductor thick-film photoresist developers, the present invention provides a thick-film photoresist developer composition for integrated circuits, which has low foam, is easy to rinse, has good wettability, does not produce residue on the chip, and is environmentally friendly.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A thick film photoresist developer composition for integrated circuits. The components and their mass percentages in the composition are as follows: 0.1-5% inorganic base, 0.1-5% development enhancer, 0.1-5% stabilizer, 0.1-2% surfactant, and the balance is water.

[0009] Furthermore, the chemical structural formula of the surfactant is: ,

[0010] wherein n is an integer from 1 to 15, p and e are integers from 1 to 6, and b is the abbreviation of block. The preparation method comprises the following steps:

[0011] (1) Synthesis of intermediate 1

[0012]

[0013] 1.1 mol of alkyl alcohol and an aqueous solution containing 0.02 mol of potassium hydroxide were placed in a reactor. The temperature was raised to 135°C and the pressure was increased to 0.2 MPa. 1-3 mol of propylene oxide was then added dropwise. After reacting for 4 hours, the temperature was lowered and the pressure was reduced to neutralize. The temperature was then raised to 120°C and the pressure was increased to 0.2 MPa. An aqueous solution containing 0.02 mol of potassium hydroxide and 1-3 mol of ethylene oxide were further added to the obtained product 2. The reaction was continued for 4 hours and the temperature was lowered to obtain intermediate 1.

[0014] (2) Synthesis of intermediate 2

[0015]

[0016] Under heating conditions, 0.1 mol of sodium hydride, 0.1 mol of tetrahydrofuran, 0.02 mol of sodium chloroacetate and 0.01 mol of hydrochloric acid were added dropwise to 0.01 mol of intermediate 1, and the reaction was carried out at 130°C for 24 hours to obtain intermediate 2;

[0017] (3) Synthesis of surfactants

[0018]

[0019] A 10% by mass sodium hydroxide solution was added to the obtained intermediate 2 until the system pH was about 8, and the mixture was reacted in an ice-water bath for 4 hours to obtain the surfactant.

[0020] Furthermore, the inorganic base is selected from any one or more of potassium hydroxide, lithium hydroxide, sodium hydroxide, calcium hydroxide, barium hydroxide, rubidium hydroxide, cesium hydroxide, francium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, sodium borate, sodium metasilicate, trisodium phosphate, etc.

[0021] Furthermore, the development enhancer is selected from one or more of boric acid, sodium tetraborate, sodium metaborate, potassium tetraborate, potassium metaborate, sodium pentaborate, potassium pentaborate, potassium borohydride, sodium borohydride and the like.

[0022] Furthermore, the stabilizer is selected from one or more of ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol butyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, dimethyl sulfoxide, diphenyl sulfoxide, vinyl pyrrolidone, etc.

[0023] Furthermore, the water is high-purity water with a resistance value greater than 18 MΩ / cm.

[0024] Furthermore, the thick film photoresist developer composition is prepared by adding an inorganic base and a stabilizer to water to form a uniform system at a stirring speed of 200 rpm, and then adding a development enhancer and a surfactant, and mixing them uniformly to obtain a uniform, stable, clear and transparent composition.

[0025] The surfactant provided by the present invention has good solubility in inorganic alkaline systems, ensuring both a high development rate and uniform development performance during the development process, thereby avoiding poor development due to film thickness issues. Furthermore, the surfactant improves the dispersibility of the developer in the photoresist, preventing photoresist residue, thereby helping to improve the precision of the developed pattern. Furthermore, the surfactant has low foaming properties, is easy to rinse, has good wettability, does not leave residue on the chip, and is environmentally friendly.

[0026] The significant advantages of the present invention are:

[0027] The surfactant used in the present invention belongs to the class of e-surfactants, which have a low critical micelle concentration, low foaming properties, and good wettability. As the chain length increases, the oil solubilizing ability also increases. The presence of the PPO-b-PEO linking group in its structure can reduce the optimal salinity required to produce the lowest interfacial tension. At the same time, the presence of ethylene oxide in the surfactant can play a certain role in development uniformity. Ethylene oxide has good cleaning ability and can emulsify the photoresist, thereby ensuring pattern accuracy. The introduction of PO can reduce the impact of foam, avoiding the increase of foam caused by the introduction of surfactants during the development process, which may cause downtime during development. Alkanes of specific chain lengths can emulsify the photosensitive resin in the photoresist to disperse the photoresist, avoiding the situation where the photoresist clogs the filter element after development. In addition, the presence of the PPO linking group reduces the adsorption capacity in the mixed system, which can improve the rinsing ability and avoid the photoresist residue on the chip, resulting in poor subsequent process. In summary, the surfactant used in the present invention can occupy a larger surface adsorption area, thereby increasing the development speed. The carboxylate salt can improve the solubility of the entire system in water. It has good thermal stability, low toxicity, good water solubility, and is very environmentally friendly. When used in the development of thick-film photoresists for integrated circuits, this surfactant can ensure complete thick-film photoresist development, improve pattern accuracy, reduce photoresist residue on the chip, increase development speed, reduce foaming, and increase the dispersibility of the photoresist in the developer, resulting in excellent development performance. DETAILED DESCRIPTION

[0028] A thick film photoresist developer composition for integrated circuits. The components and their mass percentages in the composition are as follows: 0.1-5% inorganic base, 0.1-5% development enhancer, 0.1-5% stabilizer, 0.1-2% surfactant, and the balance is water.

[0029] The inorganic base is selected from any one or more of potassium hydroxide, lithium hydroxide, sodium hydroxide, calcium hydroxide, barium hydroxide, rubidium hydroxide, cesium hydroxide, francium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, sodium borate, sodium metasilicate, trisodium phosphate, etc.

[0030] The development enhancer is selected from one or more of boric acid, sodium tetraborate, sodium metaborate, potassium tetraborate, potassium metaborate, sodium pentaborate, potassium pentaborate, potassium borohydride, sodium borohydride and the like.

[0031] The stabilizer is selected from one or more of ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol butyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, dimethyl sulfoxide, diphenyl sulfoxide, vinyl pyrrolidone, and the like.

[0032] The water is high-purity water with a resistance value greater than 18 MΩ / cm.

[0033] The chemical structural formula of the surfactant is: ,

[0034] Wherein n is an integer of 1 to 15, p and e are integers of 1 to 6, and b is used to define the type of surfactant. The preparation method comprises the following steps:

[0035] (1) Synthesis of intermediate 1

[0036] 1.1 mol of alkyl alcohol and an aqueous solution containing 0.02 mol of potassium hydroxide were placed in a reactor. The temperature was raised to 135°C and the pressure was increased to 0.2 MPa. 3 mol of propylene oxide was then added dropwise. After reacting for 4 hours, the temperature was lowered and the pressure was reduced to neutralize. The temperature was then raised to 120°C and the pressure was increased to 0.2 MPa. An aqueous solution containing 0.02 mol of potassium hydroxide and 3 mol of ethylene oxide were added. After reacting for 4 hours, the temperature was lowered to obtain intermediate 1.

[0037] (2) Synthesis of intermediate 2

[0038] In a three-necked flask equipped with a stirring and reflux device, 0.01 mol of intermediate 1 was added, and then 0.1 mol of sodium hydride, 0.1 mol of tetrahydrofuran, 0.02 mol of sodium chloroacetate and 0.01 mol of hydrochloric acid were added dropwise into the system under heating conditions. The reaction was carried out at 130°C for 24 hours to obtain intermediate 2.

[0039] (3) Synthesis of surfactants

[0040] A 10% by mass sodium hydroxide solution was added to the obtained intermediate 2 until the system pH was about 8, and the mixture was reacted in an ice-water bath for 4 hours to obtain the surfactant.

[0041] The thick film photoresist developer composition is prepared by adding an inorganic base and a stabilizer into water to form a uniform system at a stirring speed of 200 rpm, then adding a development enhancer and a surfactant, and mixing them uniformly to obtain a uniform, stable, clear and transparent composition.

[0042] In order to make the contents of the present invention easier to understand, the technical solutions of the present invention are further described below in conjunction with specific implementation methods, but the present invention is not limited thereto.

[0043] Preparation of Additive A

[0044] Step 1: Synthesis of Intermediate 1

[0045] 1.1 mol of lauryl alcohol and 50 ml of an aqueous solution containing 0.02 mol of potassium hydroxide were weighed separately in an autoclave, the temperature was raised to 50°C, the water was removed under reduced pressure, the air in the autoclave was replaced with nitrogen, the pressure was increased to 0.2 MPa, the temperature was continued to be raised to 135°C, and the pressure was released; 3.0 mol of propylene oxide was added dropwise to the autoclave, the temperature was lowered to 70°C after aging for 4 h, the system was neutralized with glacial acetic acid to pH = 8, the temperature was continued to be raised to 120°C, the pressure was increased to 0.2 MPa, 3.0 mol of ethylene oxide and an aqueous solution containing 0.02 mol of potassium hydroxide were added dropwise, the reaction was aged for 4 h, the pH was adjusted to 8 with glacial acetic acid, the pressure was reduced to 0.02 MPa, and the unreacted ethylene oxide and propylene oxide in the system were removed to obtain intermediate 1.

[0046] Step 2: Synthesis of Intermediate 2

[0047] In a three-necked flask equipped with a stirring and reflux device, add 0.01 mol of intermediate 1, 0.1 mol of sodium hydride, and 0.1 mol of tetrahydrofuran, raise the temperature to 130°C, and add 0.02 mol of sodium chloroacetate and 0.01 mol of hydrochloric acid while stirring. React for 4 hours to obtain intermediate 2.

[0048] Step 3: Synthesis of surfactant

[0049] Add intermediate 2 to a dry three-necked flask, and add 10% NaOH solution by mass until the system pH is about 8. React in an ice-water bath for 4 hours, centrifuge to remove inorganic salts, add an appropriate amount of anhydrous sodium sulfate to the supernatant, let it stand to remove water, and evaporate the supernatant to remove the solvent to obtain surfactant A.

[0050] According to FTIR analysis, the surfactant A obtained had a peak at 1110 cm -1 The COC stretching vibration peak near 3155 cm -1 Nearby is the CH bending vibration peak, 1456 cm -1Nearby is the -CH3 bending vibration peak, 2856 cm -1 and 2969 cm -1 -CH2 stretching vibration peak, 2100cm -1 The -CH2-C stretching vibration peak is at .

[0051] according to 1 H NMR ( d , DMSO, 300 MHz) analysis, and its chemical shift is ( d ):0.88(t, 3H, -CH3);1.26(m,22H,-C-CH2);1.43(t, 2H, CH2-CC);3.35(m, 14H, -OC-);3.54(S, 4H, OCCO);3.60(t,10H, O-CH2-C);4.31(s, 2H, O-CH2-C=O).

[0052] according to 13 C NMR ( d , DMSO, 300 MHz) analysis, and its chemical shift is ( d ):14.1;17.6;29.3;29.6;72.6;75.7;78.1;87.9;175.4.

[0053] According to HRMS analysis, its molecular formula is C 38 H 75 NaO 12 , m / z: 746.51.

[0054] The above results prove that the sodium lauryl alcohol polyoxypropylene ether-b-polyoxyethylene ether acetate surfactant with n=12, p=6, and e=3 was successfully synthesized.

[0055] Examples and Comparative Examples: Thick film photoresist developer compositions for integrated circuits.

[0056] According to the compositions and mass percentages shown in Table 1, developer compositions of Examples and Comparative Examples were prepared respectively.

[0057] Table 1

[0058]

[0059] Determination of developing performance of integrated circuit thick film photoresist developer composition

[0060] In order to evaluate the developing effects of the developer compositions of Examples 1-8 and Comparative Examples 1-8 on thick film photoresists, relevant tests were conducted through the following experiments.

[0061] The test method is as follows:

[0062] 1. Optical microscope detection

[0063] A 10μm thick photoresist film was spin-coated on a 6-inch, cleaned wafer at a rotation speed of 450, then partially dried under reduced pressure and vacuum to remove the solvent. The film was then cured in an oven at 105°C for 150s. The mask pattern of a specific line width was transferred to the sample wafer through an exposure machine to obtain a thick-film photoresist sample wafer with a thickness of 10μm.

[0064] Dilute the developer to the concentration specified in the process, adjust the temperature to 23°C, and spray the developer at a fixed pressure on the sample at 60 rpm in an oscillating manner for 160 seconds. Then rinse with high-purity water, blow dry with nitrogen, and bake in a 130°C oven for 30 minutes. Observe under a microscope:

[0065] 1. Whether the developed graphics are clear;

[0066] 2. Whether there is any photoresist residue;

[0067] 3. Whether the line width meets the requirements;

[0068] 4. Whether there is corrosion on the wafer;

[0069] 5. Whether the developing speed meets the requirements.

[0070] 2. Temperature stability:

[0071] Fill test tubes with 10mL of developer solution of different formulations, add a mercury thermometer, and place them in a water bath. Slowly heat. Stop heating when the developer solution becomes turbid or stratified. Record the relevant temperature and make the following benchmark evaluation:

[0072] ○: >35℃;

[0073] ×:<35℃.

[0074] 3. Dispersion stability:

[0075] After vacuum drying, scrape the photoresist off the sample wafer and collect it. Take 50g of each developer solution of different formulations into a conical flask, add 1g of the previously collected photoresist powder, stir for 10 minutes, filter through 1μm filter paper, and dry the filter paper at 110°C for 1 hour. Weigh and evaluate according to the following criteria:

[0076] ○: Net weight <0.2g;

[0077] ×: Net weight > 0.2g.

[0078] The test results are shown in Table 2.

[0079] Table 2

[0080]

[0081] From Tables 1 and 2, it can be seen that the developer compositions obtained in Examples 1-8 are uniform and stable, have excellent dispersibility for thick-film photoresists, ensure clear graphics while ensuring development speed, meet mass production requirements for line width, have no photoresist residue, have good rinsing performance, do not corrode the wafer substrate, and meet development performance standards.

[0082] Compared with Example 1, Comparative Example 1 does not add a development enhancer and a surfactant, and its development performance does not meet the standard, the development speed is slow, and there is a certain degree of corrosion to the wafer.

[0083] Compared with Example 2, Comparative Example 2 does not add stabilizers and surfactants, and its developing speed can meet the requirements, but the developing performance is poor.

[0084] Compared with Example 3, Comparative Example 3 only does not add surfactant, its developing performance is poor and the system is unstable.

[0085] Compared with Example 4, Comparative Example 4 did not add a development enhancer, and the development speed could not meet the requirement, but surfactant A was added, which was evenly dispersed and the pattern accuracy met the standard.

[0086] Compared with Examples 5-6, Comparative Examples 5-6 used surfactants such as 1601 and AES, but their dispersibility in thick film photoresist was average and easily caused photoresist residue.

[0087] Compared with Example 7, Comparative Example 7 increases the usage of the inorganic base, but too high alkalinity will cause over-development of the pattern, resulting in the pattern accuracy not meeting the requirements.

[0088] As can be seen from the above-described embodiments and comparative examples, the sodium acetate surfactant of lauryl alcohol polyoxypropylene ether-b-polyoxyethylene ether can stably exist in an inorganic base system. Its addition can improve the solubility and dispersibility of thick-film photoresists. When used in conjunction with a development enhancer and stabilizer, it can increase the development speed of the developer solution for thick-film photoresists, thereby ensuring the accuracy of the pattern and preventing phenomena such as insufficient or overdevelopment. Simultaneously, the sodium acetate surfactant of lauryl alcohol polyoxypropylene ether-b-polyoxyethylene ether has a certain emulsification property for thick-film photoresists, which can reduce the residual photoresist on the wafer. Furthermore, by adjusting the numerical values ​​of EO and PO, a large amount of foam is not generated while ensuring development, thus avoiding the occurrence of incomplete rinsing on the wafer and ensuring that the wafer is not corroded by inorganic bases during the manufacturing process. In summary, the present invention can significantly improve the developing performance of the developer, increase the developing speed, reduce cost loss, ensure pattern accuracy, have good dispersibility for thick film photoresist, be easy to rinse, produce no residue on the wafer, and be environmentally friendly by adding lauryl alcohol polyoxypropylene ether-b-polyoxyethylene ether sodium acetate surfactant and adjusting the content of inorganic base, enhancer and development stabilizer.

[0089] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A thick film photoresist developer composition for integrated circuits, characterized in that: The components of the composition and their mass percentages are calculated as follows: inorganic base 0.1-5%, development enhancer 0.1-5%, stabilizer 0.1-5%, surfactant 0.1-2%, and the balance is water. The chemical structural formula of the surfactant is: , Wherein, n is an integer of 1 to 15, and p and e are integers of 1 to 6.

2. A thick film photoresist developer composition for integrated circuits according to claim 1, characterized in that: The inorganic base is selected from any one or more of potassium hydroxide, lithium hydroxide, sodium hydroxide, calcium hydroxide, barium hydroxide, rubidium hydroxide, cesium hydroxide, francium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, sodium borate, sodium metasilicate, and trisodium phosphate.

3. A thick film photoresist developer composition for integrated circuits according to claim 1, characterized in that: The development enhancer is selected from one or more of boric acid, sodium tetraborate, sodium metaborate, potassium tetraborate, potassium metaborate, sodium pentaborate, potassium pentaborate, potassium borohydride, and sodium borohydride.

4. A thick film photoresist developer composition for integrated circuits according to claim 1, characterized in that: The stabilizer is selected from one or more of ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol butyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, dimethyl sulfoxide, diphenyl sulfoxide, and vinyl pyrrolidone.

5. The thick film photoresist developer composition for integrated circuits according to claim 1, characterized in that: The water is high-purity water with a resistance value greater than 18 MΩ / cm.

6. The thick film photoresist developer composition for integrated circuits according to claim 1, characterized in that: The preparation method comprises the following steps: adding an inorganic base and a stabilizer into water, stirring at a speed of 200 rpm to form a uniform system, then adding a development enhancer and a surfactant, and mixing them uniformly to obtain a uniform, stable, clear and transparent composition.

Images