Cleaning agent and cleaning process for silicon substrate residues after dry etching

Abstract

The invention discloses a cleaning agent for silicon substrate residues after dry etching. The cleaning agent comprises 0.01%-11% of fluoride, 50%-85% of a polar organic solvent, 0.01%-10% of a pH value regulator, 0.01%-3% of a corrosion inhibitor and 2%-30% of water. The pH value of the silicon-based residual cleaning agent is 4-6; the fluoride comprises fluorine-containing inorganic acid, the fluorine-containing inorganic acid is hydrofluoric acid and / or fluoboric acid, and the mass percent of the fluorine-containing inorganic acid in the cleaning agent is 0.01%-1.7%. The cleaning agent for silicon substrate residues after dry etching can effectively remove SIO / SINx residues in micropores after a dry etching process, has no obvious corrosion on copper, MTD, ITO and the like, has small side etching amount on the side walls of the micropores, and is beneficial to maintaining the sizes and structures of the micropores after dry etching and before cleaning. The invention further discloses a method for cleaning silicon substrate residues after dry etching.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of silicon oxide film layer wet etching, in particular to a cleaning agent for cleaning silicon-based residues after dry etching and a cleaning process. BACKGROUND

[0002] Dry etching, also known as plasma etching, is a technology that uses high-frequency electric fields to excite gas to form plasma to remove the etched material through physical sputtering and chemical reaction. Dry etching is mainly used to accurately control the shape and size of display pixels and manufacture key components such as thin film transistors (TFT), and has the characteristics of high precision, high efficiency and high selectivity of etched materials.

[0003] In some specific processes, the dry etching layer structure of the workpiece includes a laminated SINx layer and a SIO layer, the micro-hole side formed by partial dry etching has a locally exposed ITO (indium tin oxide) layer, the hole bottom material is copper or MTD (molybdenum nickel titanium) and has a columnar dry etching residue, and the dry etching residue has a laminated structure consistent with the SINx layer and the SIO layer. The usual method for removing the above dry etching residue is wet cleaning, that is, using a cleaning agent with a predetermined composition to treat the workpiece, and the cleaning requirements are as follows: removing the columnar dry etching residue at a predetermined high cleaning rate while ensuring that the photoresist (PR) near the hole, the micro-hole sidewall, the ITO, the copper hole bottom and the MTD hole bottom are not significantly damaged and corroded, and the side etching is controlled to be small.

[0004] The main components of the conventional wet silicon-based residue cleaning agent are hydrofluoric acid, ammonium fluoride, water and a metal protective agent (such as a copper protective agent). The silicon-based residue cleaning agent with high concentration of hydrofluoric acid acts on the above-mentioned workpiece, which is easy to cause defects such as micro-hole sidewall cracking or damage, ITO damage, and excessive side etching. SUMMARY

[0005] One of the purposes of the present application is to overcome the defects in the prior art and provide a cleaning agent for cleaning silicon-based residues after dry etching, which can effectively remove the dry etching residue while not significantly damaging the ITO, copper hole bottom and MTD hole bottom of the micro-hole side of the workpiece.

[0006] In order to achieve the above technical effects, the technical scheme of the present application is as follows: a cleaning agent for cleaning silicon-based residues after dry etching, comprising: 0.01% to 11% of a fluoride, 50% to 85% of a polar organic solvent, 0.01% to 10% of a pH value adjusting agent, 0.01% to 3% of a corrosion inhibitor and 2% to 30% of water. The pH value of the silicon-based residue cleaning agent is 4 to 6. The fluoride contains a fluorine-containing inorganic acid, and the fluorine-containing inorganic acid is hydrofluoric acid and / or fluoroboric acid. The mass percentage of the fluorine-containing inorganic acid in the cleaning agent is 0.01% to 1.7%.

[0007] The mass percentage of the fluorine-containing inorganic acid in the cleaning agent can be 0.01%, 0.05%, 0.1%, 0.3%, 0.5%, 0.7%, 1%, 1.4%, 1.7%, or a range between any two of the above values as the maximum and minimum values, and further, the mass percentage of the fluorine-containing inorganic acid in the cleaning agent is 0.01%-1%.

[0008] Preferably, the fluoride further comprises 1%-15% of a fluorine salt, based on 100% of the mass of the cleaning agent. The mass percentage of the fluorine salt in the cleaning agent can be 1%, 4%, 7%, 10%, 12%, 15%, or a range between any two of the above values as the maximum and minimum values, and further, the mass percentage of the fluorine salt in the cleaning agent is 1%-10%.

[0009] Preferably, the polar organic solvent comprises 50%-80% of a C2-C5 monoalcohol and / or a dihydric alcohol and 0.5%-10% of a viscosity modifier, based on 100% of the mass of the cleaning agent; and the viscosity modifier is at least one selected from a condensate of ethylene glycol and a polyhydric alcohol having 3 or more carbon atoms. Further, the viscosity modifier is at least one selected from a polyhydric alcohol having 3 or more carbon atoms.

[0010] Preferably, the pH value regulator comprises an organic base A and an organic acid A; the organic base A is at least one selected from a C2-C6 alcohol amine, a dihydric amine, a polyhydric amine, and a pyrrolidone; and the organic acid A is at least one selected from a C2-C6 dihydric acid, a polyhydric acid, and a hydroxy acid.

[0011] Preferably, the pH value regulator further comprises an inorganic acid, and the inorganic acid is at least one selected from hydrochloric acid, sulfuric acid, and phosphoric acid; and further, the inorganic acid is phosphoric acid.

[0012] Preferably, the corrosion inhibitor comprises 0.01%-2.5% of a copper protective agent, based on 100% of the mass of the cleaning agent. Further, the copper protective agent is a reducing organic acid. Further, the reducing organic acid is at least one selected from ascorbic acid and D-erythorbic acid.

[0013] The mass percentage of the copper protective agent in the cleaning agent can be 0.01%, 0.05%, 0.1%, 0.3%, 0.5%, 0.7%, 1%, 1.5%, 2%, 2.5%, or a range between any two of the above values as the maximum and minimum values, and further, the mass percentage of the reducing organic acid copper protective agent is 0.01%-1.5%.

[0014] Preferably, the corrosion inhibitor comprises 0.01% to 1% of ITO protective agent, based on 100% of the mass of the cleaning agent. The ITO protective agent is at least one selected from the group consisting of sugar alcohol protective agent, imidazolinone protective agent, pyrimidine, phenol, amino acid protective agent, thiourea protective agent, and low-molecular-weight polyethylene glycol. Further, the ITO protective agent is at least one selected from the group consisting of amino acid protective agent.

[0015] The mass percentage of the ITO protective agent in the cleaning agent can be 0.01%, 0.05%, 0.1%, 0.3%, 0.5%, 0.7%, or 1%, or a range with the above two values as the maximum and minimum values, and further, the mass percentage of the ITO protective agent in the cleaning agent is 0.01% to 0.3%.

[0016] Preferably, the mass percentage of the organic base A is 0.01% to 2.5% and the mass percentage of the organic acid A is 0.1% to 5%, based on 100% of the mass of the cleaning agent.

[0017] The mass percentage of the organic base A in the cleaning agent can be 0.01%, 0.1%, 0.5%, 1%, 1.5%, 2%, or 2.5%, or a range with the above two values as the maximum and minimum values, and the mass percentage of the organic acid A can be 0.1%, 0.5%, 1%, 2%, 3%, 4%, or 5%, or a range with the above two values as the maximum and minimum values.

[0018] Preferably, the cleaning agent further comprises 0.01% to 1% of surfactant, based on 100% of the mass of the cleaning agent.

[0019] The mass percentage of the surfactant in the cleaning agent can be 0.01%, 0.05%, 0.1%, 0.3%, 0.5%, 0.7%, or 1%, or a range with the above two values as the maximum and minimum values.

[0020] The second object of the present application is to provide a cleaning process for silicon-based residues after dry etching, which comprises the wet processing of the workpiece after dry etching by the cleaning agent for silicon-based residues after dry etching. Further, the wet processing temperature is 15 to 40℃. Further, the wet processing temperature is 22 to 33℃. Further, the cleaning time is 30s to 120s. Further, the cleaning time is 40s to 60s.

[0021] The wet processing includes but is not limited to soaking, and the wet processing temperature can be the temperature of the cleaning agent for soaking the workpiece.

[0022] The advantages and benefits of the present application are that: The cleaning agent for the silicon-based residue after dry etching is based on a low concentration of fluorine-containing inorganic acid, and the polar organic solvent moderates the reaction rate of the fluorine-containing inorganic acid with the columnar residue in the micropores after dry etching. The cleaning agent with a pH value of 4-6 can effectively remove the SIO / SINx residue in the micropores after the dry etching process, has no obvious corrosion on copper, MTD, ITO, etc., has a small amount of side etching on the micropore wall, and is beneficial to maintaining the size and structure of the micropores before cleaning after dry etching. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a top SEM photo of the target workpiece before etching; Figure 2 is a local SEM photo of the target workpiece before etching; Figure 3 is another local SEM photo of the target workpiece before etching; Figure 4 is a top SEM photo of the target workpiece after etching in Example 2; Figure 5 is a sidewall SEM photo of the target workpiece after etching in Example 2; Figure 6 is a top SEM photo of the target workpiece after etching in Comparative Example 1; Figure 7 is a sidewall SEM photo of the target workpiece after etching in Comparative Example 1; Figure 8 is a sidewall SEM photo of the target workpiece after etching in Example 6; Figure 9 is a top SEM photo of the target workpiece after etching in Comparative Example 5; Figure 10 is a top SEM photo of the target workpiece after etching in Comparative Example 6; Figure 11 is a top SEM photo of the target workpiece after etching in Example 8; Figure 12 is a top SEM photo of the target workpiece after etching in Example 10. DETAILED DESCRIPTION

[0024] The specific embodiments of the present application will be further described below in conjunction with the drawings and examples. The following examples are only used to more clearly illustrate the technical solutions of the present application, and cannot be used to limit the protection scope of the present application.

[0025] Fluoride salt The fluorine salt provides fluorine ions to generate hydrofluoric acid with hydrogen ions to dissolve SINx, SIO. The hydrofluoric acid in the cleaning agent has a predetermined initial concentration, and too high a concentration will cause serious damage to ITO and corrosion of copper, and serious side etching of the hole sidewall; the fluorine salt can be selected from ammonium fluoride and / or ammonium hydrogen fluoride.

[0026] Polar organic solvent The C2-C5 monohydric alcohol and / or dihydric alcohol in the polar organic solvent is used to slow the corrosion rate of SINx, SIO by hydrofluoric acid, and too high a content of the organic solvent will cause the cleaning effect to deteriorate. The viscosity regulator is used to increase the overall viscosity of the cleaning agent and slow the lateral erosion of the cleaning agent.

[0027] The C2-C5 monohydric alcohol and / or dihydric alcohol is selected from ethanol, propanol, isopropanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, 3-methyl-1-butanol, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol; and the viscosity regulator can be at least one of triethylene glycol, tetraethylene glycol, glycerol, and butanetriol.

[0028] pH value regulator The pH value regulator is used to stabilize the pH value in the range of 4-6 to obtain a stable SINx, SIO corrosion rate. Too high a pH value will cause the cleaning effect to deteriorate, with residues remaining at the bottom of the hole, and too low a pH value will exacerbate side etching.

[0029] The organic acid is at least one selected from citric acid, D-malic acid, malonic acid, lactic acid, oxalic acid, and acetic acid; and the organic base is at least one selected from ethanolamine, diethanolamine, triethanolamine, isopropanolamine, diisopropanolamine, triisopropanolamine, ethylenediamine, hydroxyethylethylenediamine, propylenediamine, 3-diethylaminopropylamine, NMP, and isobutanolamine. Further, the organic acid is at least one selected from citric acid, D-malic acid, or lactic acid, and the organic base is at least one selected from ethanolamine, diethanolamine, triethanolamine, isopropanolamine, diisopropanolamine, triisopropanolamine, and isobutanolamine.

[0030] Copper protection agent The copper protection agent is used to slow the corrosion rate of copper at the bottom of the hole.

[0031] The copper protective agent is at least one selected from the group consisting of benzotriazole, methylbenzotriazole, imidazole, 2-mercapto-1-methylimidazole, 1,2,3-triazole, 5-aminotetrazole, hydroxyethylidene diphosphonic acid, aminotri(methylene) phosphonic acid, diethylene triamine penta(methylene) phosphonic acid, 2-phosphono-1,2,4-butanetricarboxylic acid, hydroxyphosphonoacetic acid, phosphono butane tricarboxylic acid, and a reducing organic acid, wherein the reducing organic acid includes ascorbic acid, D-erythorbic acid, an imino acid, the imino acid contains an imino and a carboxyl functional group, and includes but is not limited to iminodiacetic acid, iminodipropionic acid, and iminodisuccinic acid.

[0032] ITO protective agent The ITO protective agent functions to reduce damage to the ITO layer exposed on the side of the hole during the cleaning process.

[0033] The ITO protective agent is at least one selected from the group consisting of sorbitol, creatinine, phenol, uracil, arginine, glycine, alanine, phenylalanine, lysine, thiourea, allyl thiourea, and low molecular weight polyethylene glycol, and the low molecular weight polyethylene glycol has a molecular weight of less than 1000. Further, the ITO protective agent is at least one selected from the group consisting of arginine, glycine, alanine, phenylalanine, and lysine.

[0034] Surfactant The surfactant functions to enhance the permeability of the cleaning solution to the micropores; the surfactant can be selected from one of an anionic surfactant, a cationic surfactant, and a non-ionic surfactant, and can be specifically selected from dodecyl methane sulfonic acid, dodecyl benzene sulfonic acid, sodium dodecyl sulfate, cetyl trimethyl ammonium bromide, cetyl trimethyl ammonium chloride, alkyl phenol polyoxyethylene ether, and a fatty alcohol polyoxyethylene ether.

[0035] Based on the fluoride in the cleaning agent, the surfactant is preferably a fluorocarbon surfactant. Further, the mass percentage of the fluorocarbon surfactant in the cleaning agent is 0.01-0.2%, and the fluorocarbon surfactant is at least one selected from the group consisting of FS3100, FC-4430, FC-4434, and FS-61.

[0036] I. Silicon-based residual cleaning agent components and configuration method Hydrofluoric acid, ammonium fluoride - electronic grade Organic solvent - ethylene glycol, glycerol pH adjuster - lactic acid, phosphoric acid, triisopropanolamine, ethylenediamine Copper protective agent - benzotriazole, hydroxyethylidene diphosphonic acid, D-erythorbic acid ITO protective agent - thiourea, arginine, PEG400 Fluorocarbon surfactant - KEMFO FS3100 Water - deionized water.

[0037] Configuration of silicon-based residue cleaning agent after dry etching: configure each component by mass percentage, first dissolve the solid component in deionized water to obtain a solution, and then mix the liquid component with the above solution.

[0038] II. Configuration of etching sample substrate and cleaning process: Sample workpiece - as shown in the figure, the bottom of the micropore on the surface of the sample workpiece has a columnar polymer (dry etching residue), the side of the pore has an exposed ITO layer, the sidewall of the pore is a laminated structure, and the bottom of the pore is Cu / MTD. Figures 1-3 Etching and cleaning process of sample workpiece - the cleaning equipment keeps the silicon-based residue cleaning agent sample at 25±1℃, and the sample workpiece is introduced into the cleaning equipment; after cleaning, pure water is used for cleaning and drying, and the cleaning time is 30s.

[0039] Corrosion of SINx, SIO, and ITO samples - the cleaning equipment keeps the silicon-based residue cleaning agent sample at 25±1℃, and the SINx, SIO, and ITO workpieces are introduced into the cleaning equipment respectively; after etching, pure water is used for cleaning and drying, and the corrosion amount of the workpiece is measured by a film thickness meter.

[0040] Corrosion of Cu and MTD metal samples - the cleaning equipment keeps the silicon-based residue cleaning agent sample at 25±1℃, and the Cu and MTD workpieces are introduced into the cleaning equipment respectively; after etching, pure water is used for cleaning and drying, and the metal corrosion amount of the workpiece is measured by a film thickness meter.

[0041] III. Etching result detection and calculation of examples and comparative examples:

[0042] 1. SEM observation of residue cleaning effect at the bottom of the micropore after cleaning, side etching amount of the sidewall of the pore, and change of the ITO layer; 2. Calculation of corrosion rate of the cleaning agent on PR, SINx, SIO, ITO, Cu, and MTD according to the corrosion amount; 3. Evaluation of columnar residue cleaning effect, ITO damage, pore sidewall damage, and pore bottom copper damage using four levels of "OK, good, poor, NG". IV. Examples and comparative examples

[0043] 1. Examples and comparative examples of fluoride and pH value Examples 1-3 and comparative examples 1-3:

[0044] The cleaning results of examples 1-3 and comparative examples 1-3 are as follows:

[0045] As​Figure 4 , 5 As shown, the cleaning agent in Example 2 completely removed the SIO / SINx residue in the micropores, leaving no columnar structure, and there was no obvious damage to ITO, the sidewalls of the pores, and the bottom of the pores; like Figure 6 , 7 As shown, the cleaning agent in Comparative Example 1 completely removed the columnar residue, but there was significant damage to the ITO and the sidewalls of the hole, while the copper at the bottom of the hole was less damaged.

[0046] When the pH value of the silicon-based residual cleaning agent is 3.6 or the hydrofluoric acid concentration is too high, ITO and the hole sidewalls are severely damaged, and the side marks are severe; while when the pH value is 6.8, the corrosion rate of SINx and SiO by the silicon-based residual cleaning agent decreases significantly, that is, the cleaning ability decreases.

[0047] 2. Examples 4-6 and Comparative Examples 4 and 5 concerning polar organic solvents:

[0048] The cleaning results of Examples 4-6 and Comparative Examples 4 and 5 are as follows:

[0049] like Figure 8 As shown, the cleaning agent in Example 6 effectively scratches the sidewalls of the hole; as Figure 9 As shown, comparative example 5 shows a significant amount of columnar structure remaining at the bottom of the hole.

[0050] Examples 4 and 5 and Comparative Examples 4 and 5 show that a suitable ratio of organic solvent is beneficial in mitigating the corrosion of SINx and SiO by fluoride ions and hydrofluoric acid. In Example 6, slight corrosion was observed on both the sidewalls and bottom of the holes. This may be because, without glycerol as a viscosity modifier, hydrofluoric acid readily reacts with the copper on the sidewalls and bottom of the holes in a lower viscosity cleaning agent.

[0051] 3. Examples 7-8 and Comparative Example 6 regarding copper protectants

[0052] The cleaning results of Examples 2, 7, 8 and Comparative Example 6 are as follows:

[0053] like Figure 10 As shown in Comparative Example 6, the cleaning agent completely removed the columnar residue, but significant copper damage was observed at the bottom of the hole; Figure 11 As shown, in Example 8, there were a small amount of columnar residue in the micropores, and the copper at the bottom of the pores was locally damaged.

[0054] Examples 2, 7, 8, and Comparative Example 6 served as controls for copper protectants. At a mass percentage of 0.5%, D-isoascorbic acid, benzotriazole, and hydroxyethylidene diphosphonic acid all showed protective effects on the copper at the bottom of the wells. D-isoascorbic acid and benzotriazole exhibited better protective effects than hydroxyethylidene diphosphonic acid. However, in Example 7, where benzotriazole was used as a copper protectant, the columnar residue cleaning effect was poor. This may be because benzotriazole has poor selectivity in the cleaning agent system and may adsorb onto the surface of SiO₂ / SIN₂x to some extent, hindering the cleaning of SiO₂ / SIN₂x. D-isoascorbic acid inhibited the oxidative dissolution of copper through copper ion reduction but had no significant effect on SiO₂ cleaning.

[0055] 4. Examples 9 and 10 and Comparative Example 7 regarding ITO protective agents

[0056] The cleaning results of Examples 2, 9, 10, and Comparative Example 7 are as follows:

[0057] like Figure 12 As shown, the cleaning agent in Example 10 completely removed the columnar residue, but significant ITO damage was observed, resulting in cracks.

[0058] Examples 2, 9, 10 and Comparative Example 7 served as controls for ITO protection agents. When the mass percentage of each was 0.05%, the ITO protection effect of arginine in the cleaning agent system was better than that of thiourea and PEG400.

[0059] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A cleaning agent for silicon-based residues after dry etching, characterized in that, include: 0.01%–11% fluoride, 50%–85% polar organic solvent, 0.01%–10% pH adjuster, 0.01%–3% corrosion inhibitor and 2%–30% water; The pH value of the silicon-based residual cleaning agent is 4 to 6; the fluoride contains a fluorinated inorganic acid, which is hydrofluoric acid and / or fluoroboric acid, and the mass percentage of the fluorinated inorganic acid in the cleaning agent is 0.01% to 1.7%.

2. The cleaning agent for silicon-based residues after dry etching according to claim 1, characterized in that, Based on the mass of the cleaning agent (100%), the fluoride also includes 1% to 15% fluoride salts.

3. The cleaning agent for silicon-based residues after dry etching according to claim 1, characterized in that, Based on the mass of the cleaning agent (100%), the polar organic solvent comprises 50% to 80% of C2 to C5 monohydric alcohols and / or dihydric alcohols and 0.5% to 10% of viscosity modifiers. The viscosity modifier is at least one selected from ethylene glycol condensates and polyols with more than C3 atoms; Furthermore, the viscosity modifier is at least one selected from polyols with C3 or more.

4. The cleaning agent for silicon-based residues after dry etching according to claim 1, characterized in that, The pH adjuster includes an organic base A and an organic acid A; the organic base A is at least one selected from C2 to C6 alkanolamines, diamines, polyamines, and pyrrolidones; the organic acid A is at least one selected from C2 to C6 diacids, polyacids, and hydroxy acids.

5. The cleaning agent for silicon-based residues after dry etching according to claim 4, characterized in that, The pH adjuster also includes an inorganic acid, which is at least one selected from hydrochloric acid, sulfuric acid, and phosphoric acid.

6. The cleaning agent for silicon-based residues after dry etching according to claim 1, characterized in that, Based on the mass of the cleaning agent (100%), the corrosion inhibitor includes 0.01% to 2.5% copper protectant; Furthermore, the copper protective agent is a reducing organic acid; Furthermore, the reducing organic acid is selected from at least one of ascorbic acid, D-isoascorbic acid, and imino acids.

7. The cleaning agent for silicon-based residues after dry etching according to claim 1, characterized in that, Based on the mass of the cleaning agent (100%), the corrosion inhibitor includes 0.01% to 1% ITO protective agent; The ITO protective agent is selected from at least one of sugar alcohol protective agents, imidazolinone protective agents, pyrimidine, phenol, amino acid protective agents, thiourea protective agents, and low molecular weight polyethylene glycol; Furthermore, the ITO protecting agent is at least one selected from amino acid-based protecting agents.

8. The cleaning agent for silicon-based residues after dry etching according to claim 4, characterized in that, Based on the mass of the cleaning agent (100%), the organic base A has a mass percentage of 0.01% to 2.5%, and the organic acid A has a mass percentage of 0.1% to 5%.

9. The cleaning agent for silicon-based residues after dry etching according to claim 1, characterized in that, The cleaning agent also includes 0.01% to 1% surfactant, based on 100% by mass of the cleaning agent.

10. A cleaning process for silicon-based residues after dry etching, characterized in that, The workpiece after dry etching is wet-treated with the cleaning agent for silicon-based residues after dry etching as described in any one of claims 1 to 9; Furthermore, the wet processing temperature is 15–40°C; Furthermore, the wet processing temperature is 22–33℃; Furthermore, the cleaning time is 30s to 120s; Furthermore, the cleaning time is 40s to 60s.

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