JP4843540B2 - Resist stripping solution containing particles and stripping method using the same - Google Patents

Description

  The present invention relates to a resist stripping solution containing particles and a stripping method using the resist stripping solution.

  In the manufacture of a semiconductor device, there is a photolithography method as a general method for transferring a pattern to a semiconductor substrate such as a silicon wafer. For example, a source region, a drain region, or the like is formed at a predetermined position by applying an implantation, and then the resist is selectively removed by dry etching or the like to manufacture a predetermined semiconductor element.

  The resist has a property that its surface is denatured and hardened by ion implantation or heating. For example, a resist subjected to ion implantation has a double structure composed of a hardened resist layer whose surface is hardened and a relatively soft resist layer which is not altered inside. In general, a resist can be easily removed with an organic solvent, but a resist subjected to ion implantation cannot be easily removed because its surface is hardened. Therefore, in this case, the removal is performed by performing the ashing process, but there is a problem that damage to the substrate remains when the removal is performed only by the ashing process. As another method, there is disclosed a method of removing a polishing pad by a mechanical process of rubbing the surface hardened layer while supplying a slurry such as silicon oxide to a resist whose surface is hardened (Patent Document 1).

  Also disclosed is a method for removing the hardened surface layer by combining the machining step with sulfuric acid cleaning, sulfuric acid / hydrogen peroxide cleaning, organic solvent cleaning, ozone cleaning, ozone steam cleaning, steam cleaning or ultraviolet irradiation cleaning. (Patent Document 1).

  Further, the above-described machining is performed by a cleaning method including at least one of scrub cleaning, megasonic cleaning, ultrasonic cleaning, two-fluid cleaning, steam cleaning, and supercritical cleaning, so that it is not necessary to supply slurry. A method for removing the cured layer is disclosed (Patent Document 1).

  However, the removal method by machining has a problem of damaging the semiconductor substrate circuit structure particularly in the case of fine wiring, and the method combining the machining step and the cleaning step requires two steps. There is a problem that it takes time and is disadvantageous in production. Moreover, in the said washing | cleaning method, the peelability of the surface hardening layer from a semiconductor substrate is inadequate, and there exists a problem which will damage a semiconductor substrate circuit structure when washing | cleaning is strengthened.

In manufacturing a liquid crystal display device, for example, in a method of manufacturing a thin film transistor panel of an active matrix liquid crystal display element, a gate insulating film and an overcoat film are often formed of silicon nitride. Then, when the silicon nitride thin film as a thin film to be processed is subjected to dry etching using a gas containing CF ₄ , SF ₆ or the like using the resist pattern formed thereon as a mask, the surface of the resist pattern is altered, A surface altered layer is formed. Therefore, in this case, a resist removal method including a process using a resist stripper containing monoethanolamine as a main component and a process of performing megasonic cleaning or ultrasonic cleaning in ozone water is disclosed ( Patent Document 2).

  In addition, a resist removal method including a process using a resist stripping solution containing monoethanolamine as a main component and a process of performing megasonic cleaning or ultrasonic cleaning in hydrogen water is disclosed (Patent Document 3). ).

  However, in the resist removal method including the step of processing using a resist stripper containing monoethanolamine as a main component and the step of performing megasonic cleaning or ultrasonic cleaning, two steps are required. Is disadvantageous in terms of production.

JP 2006-186100 A JP 2006-24822 A JP 2006-24823 A

  The problem to be solved by the present invention is to provide a resist stripping solution having excellent stripping properties. Another problem to be solved by the present invention is to provide a resist stripping method that is excellent in resist stripping and does not damage the circuit structure.

The above object has been achieved by the means described below.
<1> a resist stripping solution comprising particles and at least one compound selected from the group consisting of amine compounds and alkylene glycols,
<2> The resist stripping solution according to <1>, which contains an amine compound and alkylene glycols,
<3> The resist stripping solution according to <1> or <2>, wherein the primary particle diameter of the particles is 5 to 1,000 nm.
<4> A resist stripping method comprising the steps of preparing the resist stripping solution according to any one of <1> to <3>, and stripping the resist using the resist stripping solution. Resist stripping method,
<5> The resist stripping method according to <4>, wherein the step of stripping the resist is a step of stripping the resist by applying an ultrasonic wave to the resist stripping solution.
<6> The resist stripping method according to <4> or <5>, wherein the resist is a resist subjected to ion implantation.
<7> The resist stripping method according to any one of <4> to <6>, which does not include an ashing process.

  ADVANTAGE OF THE INVENTION According to this invention, the resist stripping solution excellent in peelability can be provided. Moreover, according to the present invention, it is possible to provide a resist stripping method that has excellent stripping properties and does not damage the circuit structure.

  The resist stripping solution of the present invention comprises particles and at least one compound selected from the group consisting of amine compounds and alkylene glycols. This will be described in detail below.

(particle)
The resist stripping solution of the present invention contains particles. The particles include inorganic particles and organic particles. Examples of inorganic particles include oxides and nitrides such as silicon, aluminum, cerium, titanium, zirconium, manganese, chromium, iron, tin, and tantalum, and composite particles of these can be used. Depending on the application, hard particles such as diamond may be used. Preferably used are silicon dioxide, aluminum oxide, cerium oxide and titanium nitride. Organic particles include styrene resin, (meth) acrylic resin (meth) acrylic ester resin, polyethylene resin, polypropylene resin, urethane resin, polyvinyl chloride resin, polyvinyl alcohol resin, polyvinyl fluoride resin, phenol resin, epoxy resin, Organic particles such as silicone resin and composite particles thereof can be used. Preferably used are epoxy resins, styrene resins and acrylic resins.

  Metal oxide inorganic particles can be obtained by well-known production methods. As a wet manufacturing method of metal oxide particles, a method of obtaining colloidal particles by a method of hydrolyzing a metal alkoxide as a starting material can be exemplified. Specifically, methyl methyl silicate is dropped at a certain rate into an alkaline aqueous solution mixed with alcohol to cause hydrolysis, and colloidal silica is produced through a period of grain growth and a period when grain growth is stopped by quenching. be able to. In addition, colloidal particles are produced using alkoxides such as aluminum and titanium.

  Further, as a dry production method of metal oxide particles, a method of obtaining fumed particles by a reaction in which a metal chloride is introduced into an oxyhydrogen flame and the dechlorinated metal is oxidized can be exemplified. Furthermore, the metal or alloy to be contained in the target substance is pulverized into a powder, which is put into an oxygen flame containing a combustion-supporting gas, causing a continuous reaction due to the heat of oxidation of the metal, and a fine A method for obtaining oxide particles has also been put into practical use. Particles produced by these combustion methods are amorphized because they experience high heat during the manufacturing process, and generally have a higher density of solids due to fewer impurities compared to wet particles. It is characterized by low density.

  The aforementioned nitride can be obtained, for example, by heating the oxide together with a reducing agent such as carbon in a nitrogen atmosphere. In this case, it is very important how the temperature distribution in the reactor is made uniform so as not to cause welding between particles while causing the reduction reaction. If the particles contain welded particles, give these powders velocity energy and disperse them by colliding them with the shielding plate. In the case of strong aggregates, disperse them in a solvent to form a slurry. In general, a method is used in which physical energy is applied and dispersed using an apparatus such as a high-pressure homogenizer.

  Furthermore, composite particles in which the oxide or nitride and the organic particles are combined can also be used. By covering the surface of the organic particles with the oxide having a particle diameter smaller than that of the organic particles, for example, composite particles that do not aggregate over a long period of time and can stably exist can be obtained.

The primary particle size of the particles contained in the resist stripper of the present invention is preferably in the range of 5 to 1,000 nm. It is more preferably 10 to 500 nm, and most preferably 20 to 500 nm. When it is within the above numerical range, the peelability is excellent.
The primary particle diameter represents the weight average particle diameter and can be measured by a dynamic light scattering method. An example of a measuring machine is “Microtrac UPA150” manufactured by Nikkiso Co., Ltd.

  The concentration of the particles can be about 0.1 to 20% by weight with respect to the resist stripping solution. When the particle concentration is less than 0.1% by weight, it is difficult to obtain a practical polishing rate. On the other hand, when it exceeds 20% by weight, the dispersibility may be deteriorated.

  The resist stripping solution of the present invention contains at least one compound selected from the group consisting of amine compounds and alkylene glycols.

(Amine compound)
In the present invention, the amine compound contained in the resist stripping solution includes hydroxylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, monoethanolamine, diethanolamine, triethanolamine, propanolamine, dipropanolamine, tripropanolamine, isopropanolamine, dipropanol. Isopropanolamine, triisopropanolamine, butanolamine, N-methylethanolamine, N-methyldiethanolamine, N, N-dimethylaminoethanol, N-ethylethanolamine, N-ethyldiethanolamine, N, N-diethylethanolamine, N- n-butylethanolamine, di-n-butylethanolamine, tetramethylammonium hydroxide, tetraethyl Ammonium hydroxide, tetrapropyl ammonium hydroxide, tetrabutyl ammonium hydroxide and salts thereof can be exemplified.
Particularly preferred examples of the amine compound include monoethanolamine, diethylamine, N-ethylethanolamine, Nn-butylethanolamine, N, N-diethylethanolamine, and tetramethylammonium hydroxide.
When the resist stripping solution of the present invention contains an amine compound, two or more amine compounds can be used in combination.

(Alkylene glycols)
Examples of alkylene glycols contained in the resist stripping solution of the present invention include glycol compounds such as ethylene glycol, propylene glycol, hexylene glycol, neopentyl glycol and the like, and their monoether or diether compounds and salts thereof. Furthermore, compounds having 2 to 4 alkylene glycols such as dialkylene glycol, trialkylene glycol and tetraalkylene glycol, and monoether or diether compounds thereof and salts thereof can be exemplified. In the present invention, a preferred alkylene group is an ethylene group. That is, in the present invention, it is preferable to use ethylene glycol as the alkylene glycol.
Specifically, ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate , Ethylene glycol diacetate and compounds having 2 to 4 ethylene glycols (diethylene glycols, triethylene glycols and tetraethylene glycols), preferably diethylene glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol dimethyl ether, Diethylene glycol Over mono butyl ether, triethylene glycol dimethyl ether, triethylene glycol monobutyl ether, diethylene glycol diacetate, may be mentioned triethylene glycol diacetate.
In the present invention, when the resist stripping solution contains alkylene glycols, two or more alkylene glycols can be used in combination.

(Concentration of amine compound)
The concentration of the amine compound is preferably 10 to 90% by weight, more preferably 20 to 70% by weight, and still more preferably 20 to 50% by weight with respect to the resist stripping solution. It is preferable that the concentration of the amine compound is 10% by weight or more and 90% by weight or less because the peeling performance is high.

(Concentration of alkylene glycols)
The alkylene glycol is preferably 10 to 90% by weight, more preferably 15 to 70% by weight, and still more preferably 20 to 50% by weight based on the resist stripping solution. It is preferable that the addition amount of the alkylene glycol is 10% by weight or more because the peeling performance is high. Moreover, it is preferable that the addition amount of the alkylene glycol is 90% by weight or less because the viscosity of the resist stripping solution does not become too high.

The resist stripping solution of the present invention contains particles and at least one compound selected from the group consisting of amine compounds and alkylene glycols, but preferably contains particles, amine compounds and alkylene glycols. In this case, the total amount of the amine compound and the alkylene glycol is preferably 10 to 90% by weight of the stripping solution, more preferably 20 to 90% by weight, and further 40 to 85% by weight. preferable. It is preferable that the total amount of the amine compound and the alkylene glycol is within the above numerical range because the peeling performance is high and the substrate is less damaged.
In addition, it is preferable to add a solvent, a pH adjuster, etc. to the resist stripping solution of the present invention.

(PH adjuster)
In the present invention, it is preferable to add an acid or a buffer as a pH adjuster in order to bring the resist stripping solution to a desired pH.
Acids or buffers include inorganic acids such as nitric acid, sulfuric acid, phosphoric acid, formic acid, acetic acid, hydroxyacetic acid, propionic acid, butyric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid , Azelaic acid, sebacic acid, lactic acid, malic acid, tartaric acid, tropic acid, benzylic acid, salicylic acid, citric acid and other organic acids, glycine, alanine, taurine and other amino acids, sodium carbonate such as carbonates, trisodium phosphate, etc. And buffering agents such as phosphate, borate, tetraborate and hydroxybenzoate. Particularly preferred acids include lactic acid and hydroxyacetic acid.

In the present invention, other components may be added to the resist stripping solution.
Solvents usable in the resist stripping solution of the present invention include water, alcohols such as methanol, ethanol, propanol, isopropanol and butanol, ethers such as tetrahydrofuran, ether alcohols such as butoxypropanol, butoxyethanol and propoxypropanol, diethyl carbonate, Carbonic acid esters such as dimethyl carbonate, ethylene carbonate and propylene carbonate, esters such as methyl acetate and ethyl acetate, sulfoxides such as dimethyl sulfoxide, N, N-dimethylformamide, N-methylformamide, N, N-dimethylacetamide, N- Amides such as methylacetamide and N, N-diethylacetamide; N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-propyl-2-pyrrolidone and the like Examples include polar organic solvents of imidazolidinones such as lactams, 1,3-dimethyl-2-imidazolidinone, 1,3-diethyl-2-imidazolidinone, 1,3-diisopropyl-2-imidazolidinone, and the like. It is done. These may be used singly or in combination of two or more. Among these, water and isopropanol can be preferably used.

  A resist stripping method comprising the steps of preparing the resist stripping solution and stripping the resist using the resist stripping solution will be described.

In the present invention, resist stripping can be performed by any known method. Specifically, a method in which the resist stripping solution and the resist to be stripped can come into contact.
Examples of the peeling method include a dipping method, a spraying method, a method using a single wafer method, and the like, and an appropriate temperature and an appropriate time are used. Although peeling temperature changes also with the solvent and method to be used, generally it is preferable that it is 20-80 degreeC, and it is more preferable that it is 40-60 degreeC. It is preferable for the peeling temperature to be within the above range because the change in concentration is small and the peeling performance can be maintained.

  The resist peeling method of the present invention is preferably repeated twice or more times to remove the resist. Repeating the stripping method twice or more is preferable because the resist removing ability is improved. The peeling method can be repeated any number of times until the resist is completely removed, but is preferably repeated 1 to 3 times, more preferably 1 to 2 times.

  In the resist stripping method of the present invention, a stripping method in which ultrasonic waves are applied to the resist stripping solution will be described. According to this method, a micro eddy current is generated by the vibration pressure of the ultrasonic wave, the stirring of the resist stripping solution around the resist is promoted, and the stripping of the resist and the resist residue can be promoted. Moreover, since peeling can be accelerated | stimulated by the effect | action of the particle | grains contained in the resist peeling liquid of this invention, a resist can be peeled reliably.

  For example, in the dipping method, a resist is applied and then pre-baked, exposed through a mask pattern, and the developed substrate (object to be processed) is immersed in a processing tank filled with a resist stripping solution. A sound wave is applied to clean the surface of the substrate. The ultrasonic vibration propagated to the lower surface of the substrate is propagated almost without being attenuated in the stripping solution, and the resist and the resist residue attached to the upper surface can be stripped. It is preferable that the treatment tank propagated to the lower surface of the substrate is equipped with an ultrasonic oscillator and a holder that holds the substrate and is irradiated with ultrasonic waves from the ultrasonic oscillator. In addition, about the process layer, the washing | cleaning apparatus currently disclosed by Unexamined-Japanese-Patent No. 2002-222787 is included.

  The ultrasonic frequency is a frequency band in the range of 0.1 to 10 MHz, and high peeling ability is recognized. Moreover, it is preferable that it is in the range of 0.8-1 MHz, and there is no possibility of dissolving the resist adhering to the substrate and damaging the substrate.

It is preferable to use a modification step using an oxidizing agent before the step of stripping the resist. In particular, a resist subjected to ion implantation modifies the resist surface by the method, and the stripping performance is improved. Any known method can be used for the reforming step. Specifically, any method such as an immersion method, a spray method, and a coating method can be used. Among these, the dipping method and the spray method are preferable, and the dipping method is more preferable.
Moreover, it is preferable that a modification process is performed at 100-160 degreeC, and it is more preferable to be performed at 120-150 degreeC.
In the modifying step, the resist is preferably contacted with the oxidizing agent for 5 to 30 minutes, more preferably 10 to 20 minutes. The contact time of 5 minutes or more is preferable because the ion-implanted resist can be modified and the resist stripping ability in the subsequent stripping process is improved. Further, it is preferable that the contact time is 30 minutes or less because the time required for the peeling method is short. Moreover, it is preferable to perform the said modification process before stripping a resist using the resist stripping solution of this invention.

(Oxidant)
Specific examples of the oxidizing agent include hydrogen peroxide, peroxide, nitrate, iodate, periodate, hypochlorite, chlorite, chlorate, perchlorate, Examples thereof include sulfates, dichromates, permanganates, ozone water, silver (II) salts, iron (III) salts, and a mixture of hydrogen peroxide and sulfuric acid. A mixture of hydrogen peroxide and sulfuric acid is more preferably used.
The oxidizing agent is preferably in the form of a solution, and as the solvent, various kinds of water such as ultrapure water ion-exchanged water and distilled water, alcohols such as methanol, ethanol and butanol, sulfoxides such as dimethyl sulfoxide, N and N -Amides such as dimethylformamide, N-methylformamide, N, N-dimethylacetamide, N-methylacetamide, N, N-diethylacetamide; N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N- Lactams such as propyl-2-pyrrolidone, imidazolidinones such as 1,3-dimethyl-2-imidazolidinone, 1,3-diethyl-2-imidazolidinone, 1,3-diisopropyl-2-imidazolidinone The polar organic solvent can be exemplified. The solvent is preferably water, alcohols, sulfoxides, or imidazolidinones, and more preferably water.
In the present invention, the oxidizing agent is preferably a solution containing hydrogen peroxide, and more preferably a mixture solution of hydrogen peroxide and sulfuric acid.

  The oxidizing agent is preferably a 5 to 30% by weight solution, more preferably a 10 to 20% by weight solution with respect to the resist stripping solution.

The resist stripping method of the present invention is suitably used for a resist stripping method subjected to ion implantation (ion implantation). With respect to a resist that has become difficult to be peeled off by ion implantation, the resist can be effectively peeled off using a resist stripping solution containing particles. Further, the resist can be reliably peeled by immersing the resist stripping solution in the treatment layer and irradiating ultrasonic waves from the back surface of the substrate to clean the surface of the substrate.
The present invention is applicable to known resists used in the semiconductor industry, and is particularly preferably used for KrF positive photoresists, but the present invention is not limited thereto.

According to the resist stripping method of the present invention, the ashing treatment can be omitted. In recent years, in semiconductor devices, a technique using a low-k film (low dielectric constant film) having a low non-dielectric constant instead of a SiO ₂ film has been developed, and accordingly, the low-k film is etched in the manufacturing process of the semiconductor device. Need to do. Conventionally, after dry etching of the film, ashing (ashing) is performed by plasma such as oxygen and ozone, and the resist is removed. However, such a process causes a problem that the low-k film is damaged. ing. In addition to the problem of substrate damage, the method of ashing using active plasma such as oxygen / ozone has a problem that it takes time to process because of the large number of processes.
Moreover, since the ashing device is provided with a chamber, the entire device becomes large. If the ashing process can be omitted in the resist stripping method of the present invention, a large chamber is not required, and the entire apparatus can be saved in space. Further, since it is not necessary to make a vacuum, it is not necessary to vacuum the chamber. For this reason, the resist can be removed in a short time.

  Examples of the present invention will be described in detail below, but the present invention is not limited to these examples.

The resist peeling test was performed as follows.
(Sample preparation)
A general-purpose resist (commercially available KrF resist) was applied on a silicon wafer so that the resist thickness was about 1,000 mm. Next, the sample coated with this resist was pre-baked, exposed through a mask pattern, and developed.
Thereafter, an ion implantation operation was performed. A sample was prepared using As ions as the ions and a dose amount of 1E ¹⁶ atoms / cm ² .

<Example 1>
(Preparation of resist stripping solution)
The resist stripping solution was prepared as follows.
Silicon dioxide particles (primary particle size 30nm) 5% by weight
Monoethanolamine 50% by weight
45% by weight of water

(Resist stripping test)
The obtained sample was immersed in a treatment tank containing a resist stripping solution, and an ultrasonic wave having a frequency of 0.8 to 1 MHz was applied from the lower surface of the substrate. The temperature of the stripping solution was 50 ° C., the immersion time was 5 minutes, and cleaning was performed with ultrapure water.
Thereafter, the presence or absence of the resist was confirmed with an optical microscope, and the peelability of the resist was evaluated.

The peelability of the resist was evaluated as follows.
A: Excellent releasability ○: Good releasability △: Remaining partially ×: Remaining most

<Examples 2 to 20>
The peelability of the resist was evaluated in the same manner as in Example 1 except that the compounds, pH adjusters, and water contained in the resist stripper were changed to the substances and addition amounts shown in Table 1. The results are shown in Table 1.

<Comparative Examples 1-6>
The peelability of the resist was evaluated in the same manner as in Example 1 except that the compounds, pH adjusters, and water contained in the resist stripping solution were changed to the substances and addition amounts shown in Table 2. The results are shown in Table 2.

<Comparative Example 7>
The resist peelability was evaluated in the same manner as in Example 1 except that the compounds, pH adjusters, and water contained in the resist stripper were the substances and addition amounts shown in Table 2 and no ultrasonic waves were applied. The results are shown in Table 2.

<Comparative Example 8>
The cured layer formed on the upper surface portion of the resist layer was removed from the obtained sample by a chemical mechanical polishing method while supplying an aluminum oxide slurry. After removing the hardened layer, the sample was immersed in sulfuric acid to peel off the resist layer and observed using a scanning electron microscope. As a result, countless scratches were observed on the surface of the silicon wafer from which the resist was removed by machining.

The symbols in the table are as shown below.
P1: Silicon dioxide particles (primary particle size 30 nm)
P2: Titanium nitride particles (primary particle diameter 100 nm)
P3: Epoxy resin particles (primary particle diameter 500 nm)
A1: Monoethanolamine A2: Nn-butylethanolamine B1: Diethylene glycol monobutyl ether B2: Triethylene glycol monobutyl ether

  The symbols in the table are the same as in Table 1. As shown in Tables 1 and 2, the resist stripping solution of the present invention is a resist stripping solution having excellent stripping properties.

<Example 21>
(Preparation of resist stripping solution)
The resist stripping solution was prepared as follows.
Silicon dioxide particles (primary particle diameter 5 nm) 10 parts by weight N, N-diethylethanolamine 30 parts by weight diethylene glycol monobutyl ether 30 parts by weight hydroxyacetic acid 1 part by weight water 30 parts by weight

(Resist stripping test)
The obtained sample was immersed in a treatment tank containing a resist stripping solution, and an ultrasonic wave having a frequency of 0.8 to 1 MHz was applied from the lower surface of the substrate. The temperature of the stripping solution was 50 ° C., the immersion time was 5 minutes, and cleaning was performed with ultrapure water.
Thereafter, the presence or absence of the resist was confirmed with a scanning electron microscope, and the peelability of the resist was evaluated.

The peelability of the resist was evaluated as follows.
A: Excellent releasability ○: Good releasability △: Remaining partially ×: Remaining most

<Examples 22 and 23 and Comparative Examples 9 and 10>
The peelability of the resist was evaluated in the same manner as in Example 21 except that the primary particle size of the particles contained in the resist stripping solution was changed to the primary particle size shown in Table 3. The results are shown in Table 3.

  As shown in Table 3, it can be said that the resist stripping solution of the present invention is a resist stripping solution having excellent stripping properties by containing particles having a primary particle diameter of 5 to 1,000 nm.

Claims (7)

  A resist stripping solution comprising particles and at least one compound selected from the group consisting of amine compounds and alkylene glycols.   The resist stripping solution according to claim 1 containing an amine compound and alkylene glycols.   The resist stripping solution according to claim 1 or 2, wherein a primary particle diameter of the particles is 5 to 1,000 nm. A resist stripping method comprising:
A resist stripping method comprising: preparing a resist stripping solution according to any one of claims 1 to 3; and stripping the resist using the resist stripping solution.   The resist stripping method according to claim 4, wherein the step of stripping the resist is a step of stripping the resist by applying ultrasonic waves to the resist stripping solution.   The resist stripping method according to claim 4 or 5, wherein the resist is a resist subjected to ion implantation.   The resist stripping method according to any one of claims 4 to 6, which does not include an ashing process.