JP5498843B2 - Two-agent type semiconductor substrate cleaning agent - Google Patents

Description

  The present invention relates to a two-agent type semiconductor substrate cleaning agent. More specifically, the present invention relates to a two-component type semiconductor substrate cleaning agent having a foaming agent component containing a carbonate and a foaming aid component containing an acidic compound.

  The manufacturing process of a semiconductor element (semiconductor device) includes various processes such as a lithography process, an etching process, and an ion implantation process. After each process is finished, before moving on to the next process, the resist residue and other impurities such as impurities remaining on the substrate surface are removed and removed, and a cleaning process is performed to clean the substrate surface. Yes.

As a conventional cleaning treatment method, a process of stripping and cleaning resist residues, fine particles, metals, natural oxide films, and the like using a mixed solution of concentrated sulfuric acid and hydrogen peroxide (hereinafter referred to as SPM as appropriate) has been frequently used. Although this method is excellent in the peelability of deposits, the oxidizing power of the processing solution is too strong, and thus damages the gate insulating film composed of a high dielectric constant (high-k) material and the substrate during processing. was there. Considering the current situation in which miniaturization of semiconductor devices is progressing, even if such a damage occurs in part, it causes electrical characteristics deterioration. In addition, the method using SPM is not always satisfactory from the viewpoint of work safety because the chemical itself may be dangerous or a rapid temperature increase may occur.
Therefore, there is a demand for a cleaning technique that has less influence on the gate insulating film, the substrate, and the like, and has higher safety. For example, it contains ammonium carbonate in a carbon dioxide atmosphere and has a pH of 7 A cleaning method for ashing residues using an aqueous solution of less than 8.6 has been proposed (Patent Document 1).

Patent No. 4017402

On the other hand, in recent years, an ion implantation amount tends to increase in an ion implantation process (ion implantation) which is one of the manufacturing processes of semiconductor elements. At that time, it is known that the ion-implanted resist is carbonized and cross-linked, and the outermost surface is altered, so that it is difficult to completely remove the resist depending on chemicals.
As the demand for higher reliability for semiconductor devices increases, the demand for substrate surface cleaning has become increasingly severe, and more efficient removal of impurities including ion-implanted resist as described above. Development of a cleaning solution for the purpose is desired.

  When the present inventors have examined the releasability of the ion-implanted resist and the like using the cleaning liquid used in the cleaning method described in Patent Document 1, results that are sufficiently satisfactory can be obtained. No further improvement was needed.

  In view of the above circumstances, the present invention can efficiently remove impurities attached to the surface of a semiconductor substrate, in particular, deposits such as ion-implanted resist, without damaging the gate insulating film or the substrate. An object is to provide an excellent cleaning agent for a two-component semiconductor substrate.

As a result of intensive studies on a cleaning solution used for cleaning a semiconductor substrate, the present inventors have found that a desired effect can be obtained by using a cleaning agent containing a predetermined component.
That is, the present inventors have found that the above problem is solved by the following configuration.

<1> A two-component type cleaning agent for a semiconductor substrate having a foaming agent component and a foaming auxiliary agent component, which are mixed and used when cleaning a semiconductor substrate,
The blowing agent component contains carbonate;
The foaming auxiliary component contains an acidic compound,
Furthermore, the foaming agent component and / or the foaming aid component contains a surfactant,
A cleaning agent for a two-component semiconductor substrate, wherein a pH of a mixed solution of the foaming agent component and the foaming auxiliary component is less than 7.5.
<2> The cleaning agent for a two-component semiconductor substrate according to <1>, wherein the surfactant is a nonionic surfactant.
<3> The carbonate is ammonium carbonate, ammonium bicarbonate, sodium bicarbonate, sodium carbonate, potassium carbonate, potassium bicarbonate, cesium carbonate, lanthanum carbonate, lithium carbonate, magnesium carbonate, manganese carbonate, nickel carbonate, strontium carbonate, The cleaning agent for a two-component semiconductor substrate according to <1> or <2>, which is a carbonate selected from the group consisting of aminoguanidine carbonate and guanidine carbonate.

<4> The acidic compound is sulfuric acid, nitric acid, boric acid, phosphoric acid, formic acid, acetic acid, propionic acid, benzoic acid, glycolic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid , Pimelic acid, maleic acid, phthalic acid, malic acid, tartaric acid, citric acid, lactic acid, glycine, alanine, aspartic acid, glutamic acid, aminomethanesulfonic acid, taurine, benzenesulfonic acid, toluenesulfonic acid, methanesulfonic acid, ethanesulfone The cleaning agent for a two-component semiconductor substrate according to any one of <1> to <3>, which is a compound selected from the group consisting of an acid and sulfamic acid.
<5> The cleaning agent for a two-component semiconductor substrate according to any one of <1> to <4>, wherein a concentration of the carbonate in the mixed solution is 0.1 to 30% by mass.
<6> The cleaning agent for a two-component semiconductor substrate according to any one of <1> to <5>, wherein the foaming agent component and / or the foaming auxiliary component contains an oxidizing agent.

<7> The cleaning agent for a two-component semiconductor substrate according to any one of <1> to <6>, wherein the surfactant is a polyoxyalkylene type nonionic surfactant.
<8> The cleaning agent for a two-component semiconductor substrate according to any one of <1> to <7>, wherein the pH of the mixed solution is less than 7.
<9> The two-component semiconductor according to any one of <1> to <8>, wherein a content of the surfactant in the foaming agent component or the foaming auxiliary component is 0.0001 to 10% by mass. Substrate cleaner.
<10> The two-component semiconductor substrate according to any one of <6> to <9>, wherein a content of the oxidizing agent in the foaming agent component or the foaming auxiliary component is 0.01 to 20% by mass. Cleaning agent.
<11> The cleaning agent for a two-component semiconductor substrate according to any one of <1> to <10>, wherein the foaming agent component has a pH of 7.5 to 12.

  According to the present invention, impurities that adhere to the surface of a semiconductor substrate, in particular, deposits such as ion-implanted resist can be efficiently peeled without damaging the gate insulating film, the substrate, and the like. Type semiconductor substrate cleaning agent can be provided.

Below, the cleaning agent for 2 agent type semiconductor substrates of this invention is explained in full detail.
The cleaning agent for a two-component type semiconductor substrate of the present invention has a foaming agent component containing carbonate and a foaming assistant component containing an acidic compound, and both are mixed and used when cleaning the semiconductor substrate. It is a cleaning agent. In addition, surfactant is contained in this foaming agent component and / or this foaming adjuvant component, and pH of the liquid mixture of a foaming agent component and a foaming adjuvant component shows less than 7.5. In the cleaning agent, carbon dioxide gas (CO ₂ ) is generated from carbonate in a mixed solution obtained by mixing the foaming agent component and the foaming agent auxiliary component, and mainly the action of the carbon dioxide gas and the acidic compound. As a result, impurities (deposits) adhering to the substrate surface are peeled off and removed.

The reason why the pH of the mixed solution is preferably less than 7.5 in the present invention will be described below. The pKa of the carbonate is 6.3 to 6.5 (pKa1), 10.2 to 10.4 (pKa2), each represented by the following formula.
_{^{CO 3 2- + H + → HCO}} 3 - (1) pKa2
HCO ₃ ⁻ + H ⁺ → H ₂ CO ₃ (2) pKa1
Further, from (2), carbon dioxide gas is generated through a reaction such as H ₂ CO ₃ → H ₂ O + CO ₂ (g) ↑. In general, pKa indicates a pH at which chemical species on both sides in the chemical reaction formula are present at 1: 1. Further, it is known that the pH deviating by 1 from pKa means that the abundance ratio of the chemical species on the right side and the left side is 10 times different. In (2) above, HCO ₃ ⁻ and H ₂ CO ₃ are present in equal amounts at pH = 6.3-6.5, and HCO at pH = 5.3-5.5 (pKa1-1). ₃ ⁻ and H ₂ CO ₃ are present at a ratio of 1:10, and at pH = 7.3 to 7.5 (pKa1 + 1), HCO ₃ ⁻ and H ₂ CO ₃ are present at a ratio of 10: 1. doing. Taking into account the presence of carbonates that contribute to foaming, the foaming reaction we expect cannot effectively occur at a pH of 7.5 or higher.
Below, the component which comprises the cleaning agent for 2 agent type semiconductor substrates is explained in full detail. In addition, the material explained in full detail below may use a commercial item, and may synthesize | combine it by a well-known method.

<Foaming agent component>
(Carbonate)
The foaming agent component constituting the two-agent type semiconductor substrate cleaning agent of the present invention contains a carbonate. The carbonate is a compound that generates carbon dioxide gas by the action of an acidic compound described later, and acts as a so-called decomposable foaming agent.
The carbonate to be used is not particularly limited as long as it is a salt compound that generates carbonic acid, and mainly includes a normal salt, an acidic salt (bicarbonate), a basic salt (carbonate hydroxide salt) and the like. For example, alkali metal or alkaline earth metal carbonate, hydrogen carbonate, ammonium carbonate, or the like can be given. More specifically, carbonates include ammonium carbonate, ammonium bicarbonate, sodium bicarbonate, sodium carbonate, potassium carbonate, potassium bicarbonate, cesium carbonate, lanthanum carbonate, lithium carbonate, magnesium carbonate, manganese carbonate, nickel carbonate, carbonate Examples include strontium, aminoguanidine carbonate, and guanidine carbonate. An anhydrous salt, a hydrated salt, or a mixture thereof can also be used. Among these, ammonium hydrogen carbonate or ammonium carbonate is preferable, and ammonium carbonate is more preferable because it is excellent in the peelability of deposits and is easy to handle.
In addition, carbonate may use only 1 type and may use 2 or more types together.

Although content of carbonate in a foaming agent component is not specifically limited, 0.1-80 mass% is preferable with respect to foaming agent component whole quantity from the point which the peelability of a deposit is more excellent, 0.5-50 The mass% is more preferable.
In addition, the content of the carbonate in the mixture of the foaming agent component and the foaming auxiliary component described later is preferably 0.1 to 30% by mass with respect to the total amount of the mixed solution from the viewpoint that the peelability of the deposit is more excellent. 0.5-30 mass% is more preferable.

(solvent)
The foaming agent component may contain a solvent as necessary. The solvent to be used is not particularly limited as long as the carbonate is dissolved, but water is usually used. In addition, the organic solvent (For example, DMSO, DMF, NMP etc. which are polar solvents) may be contained in the range which does not impair the effect of this invention.
Although content of the solvent in a foaming agent component is not specifically limited, Usually, 1-99.5 mass% is preferable with respect to foaming agent component whole quantity, and 10-99.0 mass% is more preferable.

  The pH of the foaming agent component is not particularly limited, but is preferably 7.5 to 12.0, more preferably 8.0 to 11.0 in terms of more excellent stability of the foaming agent component and more excellent peelability of the deposit. More preferred.

<Foaming aid component>
(Acidic compounds)
The foaming assistant component constituting the cleaning agent for a two-component semiconductor substrate of the present invention contains an acidic compound. The acidic compound means a compound as it is or its aqueous solution is acidic. The compound acts on the above-described carbonate to generate carbon dioxide and contributes to the peelability of the deposit.
The acidic compound used is not particularly limited. For example, sulfuric acid, nitric acid, boric acid, phosphoric acid, formic acid, acetic acid, propionic acid, benzoic acid, glycolic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid , Glutaric acid, adipic acid, pimelic acid, maleic acid, phthalic acid, malic acid, tartaric acid, citric acid, lactic acid, glycine, alanine, aspartic acid, glutamic acid, aminomethanesulfonic acid, taurine, benzenesulfonic acid, toluenesulfonic acid, Examples thereof include methanesulfonic acid, ethanesulfonic acid, and sulfamic acid.
In addition, an acidic compound may use only 1 type and may use 2 or more types together.

Of these, water-soluble organic acids are preferred because they are inexpensive and easy to handle. A more preferred embodiment is a water-soluble carboxylic acid having a carboxylic acid group. Preferable examples of the water-soluble carboxylic acid include a water-soluble aliphatic carboxylic acid. More preferably, a C1-C6 water-soluble aliphatic carboxylic acid is mentioned. Particularly preferred are aliphatic mono-, di- and tricarboxylic acids having 2 to 6 carbon atoms which may have 1 to 5 hydroxyl groups.
Specific examples of the water-soluble carboxylic acid include, for example, monocarboxylic acids such as propionic acid, ascorbic acid, lactic acid, gluconic acid and glucuronic acid, oxalic acid, malonic acid, succinic acid, malic acid, tartaric acid, phthalic acid and maleic acid. Examples thereof include dicarboxylic acids such as acids, and tricarboxylic acids such as citric acid.

Although content of the acidic compound in a foaming adjuvant component is not specifically limited, 0.01-50 mass% is preferable with respect to foaming adjuvant component whole quantity from the point which is more excellent in the peelability of a deposit | attachment, 1-50 % By mass is more preferable, and 1 to 25% by mass is particularly preferable.
In addition, the content of the acidic compound in the mixture of the foaming agent component and the foaming auxiliary component described later is 0.01 to 30% by mass with respect to the total amount of the mixed solution from the point that the peelability of the deposit is more excellent. Preferably, 0.01-10 mass% is more preferable.

(solvent)
The foaming auxiliary component may contain a solvent as necessary. The solvent used is not particularly limited as long as the acidic compound dissolves, but water is usually used. In addition, the organic solvent (For example, DMSO, DMF, NMP etc. which are polar solvents) may be contained in the range which does not impair the effect of this invention.
Although content of the solvent in a foaming adjuvant component is not specifically limited, Usually, 1-99.5 mass% is preferable with respect to foaming adjuvant component whole quantity, and 10-99.0 mass is more preferable.

  The pH of the foaming auxiliary component is not particularly limited, but is preferably 7.5 or less, more preferably 5.0 or less, in that the stability of the foaming agent component is better and the peelability of the deposit is more excellent. In addition, although a minimum is not specifically limited, 1.5 or more are preferable.

<Surfactant>
The foaming agent component and / or the foaming aid component contains a surfactant. By including the surfactant, the size of bubbles generated by the carbon dioxide gas generated in the mixture of the foaming agent component and the foaming auxiliary component described later is further controlled, and as a result, the ability to remove deposits such as resists is removed. Will improve.
Although the surfactant used is not specifically limited, For example, a cationic surfactant, an amphoteric surfactant, an anionic surfactant, a nonionic surfactant, etc. are illustrated. In particular, nonionic surfactants or anionic surfactants are more preferable and effective in terms of excellent adhesion peeling performance and suppression of reattachment of impurities peeled off the substrate surface to the substrate surface. Nonionic surfactant is particularly preferable in that it is more excellent. The surfactant can be either linear or branched.

Examples of the cationic surfactant include tetraalkylammonium salts, alkylamine salts, benzalkonium salts, alkylpyridium salts, imidazolium salts, and the like.
Examples of the anionic surfactant include sodium dodecylbenzenesulfonate, sodium lauryl sulfate, sodium alkyldiphenyl ether disulfonate, sodium alkylnaphthalenesulfonate, and the like.
Examples of amphoteric surfactants include carboxybetaine, sulfobetaine, aminocarboxylate, and imidazoline derivatives.

Nonionic surfactants include, for example, polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, glycerin fatty acid ester , Polyoxyethylene glycerin fatty acid ester, polyglycerin fatty acid ester, sucrose fatty acid ester, polyoxyethylene alkylamine, polyoxyethylene fatty acid amide, alkyl alkanolamide, acetylene glycol, polyoxyethylene adduct of acetylene glycol, and the like. Or the polyoxypropylene type compound whose oxyethylene structure in the said exemplary compound is an oxypropylene structure is illustrated.
Among these, polyoxyalkylene type nonionic surfactants are preferable in that the adhesion peeling performance is more excellent. Specific examples include polyoxyalkylene alkyl ether, polyoxyalkylene alkyl phenyl ether, polyoxyalkylene glycol fatty acid ester, polyoxyalkylene fatty acid ester, polyoxyalkylene sorbitan fatty acid ester, polyoxyalkylene fatty acid monoalkanolamide, polyoxyalkylene fatty acid And dialkanolamide. More specifically, a surfactant in which the alkylene part is ethylene or propylene can be mentioned.

Furthermore, as a preferable embodiment of the polyoxyalkylene type nonionic surfactant, a polyoxyalkylene type nonionic surfactant represented by the following general formula (1) is preferable.
R ² O— (R ¹ O) _p —H General formula (1)
In the general formula (1), R ¹ represents an ethylene group or a propylene group, and p represents an integer of 2 or more (preferably 30 or less, more preferably 10 or less). The plurality of R ¹ may be the same or different.
R ² represents a hydrogen atom or an alkyl group (preferably having 1 to 20 carbon atoms), and a hydrogen atom is preferable in that the effect of the present invention is more excellent. The alkyl group may have a substituent such as an amino group, but preferably does not contain a phenyl group as a substituent.

Preferable embodiments of the surfactant represented by the general formula (1) include polyoxyalkylene type nonionic surfactants represented by the following general formula (2) or general formula (3).
HO- (EO) _x- (PO) _y- (EO) _z- H General formula (2)
HO- (PO) _x- (EO) _y- (PO) _z- H General formula (3)
In general formula (2) and general formula (3), EO represents an oxyethylene group and PO represents an oxypropylene group. x, y, and z each independently represent an integer of 1 or more (preferably an integer of 10 or less).

The content of the surfactant contained in the foaming agent component or the foaming auxiliary component is not particularly limited, but 0.0001 to 10% by mass with respect to the total amount of each component from the viewpoint that the peelability of the deposit is more excellent. Preferably, 0.001-1 mass% is more preferable.
In addition, the content of the surfactant in the mixed liquid of the foaming agent component and the foaming auxiliary component is not particularly limited, but from the point that the peelability of the deposit is more excellent, the total amount of the mixed liquid is 0.00005 to 5 mass% is preferable and 0.0005 to 0.5 mass% is more preferable.

<Oxidizing agent>
The foaming agent component and / or the foaming aid component may contain an oxidizing agent. By including the oxidizing agent, the peelability of the deposit is further improved.
The oxidizing agent to be used is not particularly limited, and examples thereof include peroxides (for example, hydrogen peroxide), nitrates, persulfates, dichromates, permanganates, and the like. Among these, hydrogen peroxide is preferable because it is excellent in peelability of deposits and is easy to handle.

The content of the oxidizing agent contained in the foaming agent component or the foaming auxiliary component is not particularly limited, but is preferably 0.01 to 20% by mass with respect to the total amount of each component from the viewpoint that the peelability of the deposit is more excellent. 0.1 to 20% by mass is more preferable.
Further, the content of the oxidizing agent in the mixed solution of the foaming agent component and the foaming auxiliary component is not particularly limited, but 0.005 to 10% with respect to the total amount of the mixed solution from the viewpoint that the peelability of the deposit is more excellent. % By mass is preferable, and 0.05 to 10% by mass is more preferable.

<Alkaline compound>
The foaming agent component may contain an alkaline compound. By including the alkaline compound, pH adjustment is facilitated, stable foaming in the mixed solution is achieved, and the releasability of impurities is further improved.
The alkaline compound used is not particularly limited, and examples thereof include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide. The content of the alkaline compound in the foaming agent component is not particularly limited and is preferably used so as to have the above pH. Specifically, the content is preferably 0.0001 to 10% by mass and more preferably 0.0001 to 5% by mass with respect to the total amount of the foaming agent component.

<2 agent type semiconductor substrate cleaning agent>
The cleaning agent for a two-component type semiconductor substrate of the present invention is composed of a foaming agent component and a foaming auxiliary agent component, and both are mixed and used when cleaning the semiconductor substrate.
The pH of the mixed solution is adjusted to be less than 7.5. When the pH of the mixed liquid is 7.5 or more, the foaming of carbon dioxide gas does not proceed sufficiently, and the peelability of the deposit is poor.
The pH of the mixed solution is preferably less than 7.0, more preferably 6.5 or less, more preferably 2.0 or more, and even more preferably 3.5 or more, from the viewpoint that the peelability of the deposit is more excellent. In addition, although pH of a liquid mixture may change with foaming, it is preferable to maintain pH in the said range during a process.

  The mixing mass ratio of the foaming agent component and the foaming auxiliary agent component (foaming agent component / foaming auxiliary component) is not particularly limited as long as the pH of the mixed solution is within the above range, but is 0.01 from the viewpoint of handleability. A range of ˜100 is preferable.

<Washing method>
The method of cleaning the semiconductor substrate using the two-agent type semiconductor substrate cleaning agent of the present invention is not particularly limited, but a foaming agent component and a foaming auxiliary agent component are supplied to the semiconductor substrate to show a pH of less than 7.5. A method of cleaning the semiconductor substrate in a mixed solution of the agent component and the foaming auxiliary component is preferable. Generally, the resist (photoresist) after ion implantation is carbonized, so it is difficult to remove and remove with chemicals, but by using the above cleaning agent, the carbonized resist residue can be easily removed and removed from the semiconductor substrate. It becomes possible to do.

As a general method for manufacturing a semiconductor device, first, a high dielectric constant material (for example, HfSiO ₄ ) is used on a silicon substrate (for example, an ion-implanted n-type or p-type silicon substrate) by using a technique such as sputtering. , ZiO ₂ , ZiSiO ₄ , Al ₂ O ₃ , HfO ₂ , La ₂ O ₃ ) or the like, or a gate electrode layer made of polysilicon or the like (etched layer forming step) ). Next, a resist is applied on the formed gate insulating film and the gate electrode layer, and a predetermined pattern is formed by photolithography. After the pattern formation, unnecessary portions of the resist are developed and removed (resist development process), and the non-mask area is dry etched or wet etched (etching process) using this resist pattern as a mask (etching process), thereby obtaining a gate insulating film, a gate electrode layer, etc. Remove. Thereafter, in an ion implantation process (ion implantation step), ionized p-type or n-type impurity elements are implanted into the silicon substrate, and p-type or n-type impurity implantation regions (so-called source / drain regions) are formed on the silicon substrate. Form. Thereafter, as necessary, an ashing process (ashing process) is performed, and then a process of removing the resist film remaining on the substrate is performed.

The cleaning method using the cleaning agent for a two-component semiconductor substrate of the present invention is a method that is performed at the time of manufacturing a semiconductor element, and may be performed after any step. Specifically, for example, it can be performed after resist development, after dry etching, after wet etching, after ashing, or after ion implantation. In particular, it is preferably performed after the ion implantation step (ion implantation) from the viewpoint of good releasability of the resist carbonized by ion implantation.
More specifically, a step of preparing a semiconductor substrate (for example, a p-type or n-type silicon substrate) on which a layer to be etched (gate insulating film and / or gate electrode layer) is formed (etched layer forming step) ), A step of forming a photoresist pattern on the etching target layer (resist formation step), a step of selectively etching the etching target layer using the photoresist pattern as an etching mask (etching step), an ion It is preferable to apply the cleaning agent of the present invention to a semiconductor substrate obtained through an implantation step (ion implantation step).
Note that the ion implantation step can be performed by a known method, and can be performed at a dose of 10 ¹⁵ to 10 ¹⁸ atoms / cm ² using ions of argon, carbon, neon, arsenic, and the like.

As another preferred embodiment of the cleaning method using the two-agent type semiconductor substrate cleaning agent of the present invention, after performing the ion implantation step as described above, the substrate is further subjected to an ashing treatment or a general-purpose cleaning liquid. After the removal of large dust on the substrate and the removal of the bulk layer by the above, there is a method of performing the cleaning method using the two-component type semiconductor substrate cleaning agent of the present invention on the dust and various layers that are difficult to remove. It is done.
When the cleaning method using the cleaning agent of the present invention is performed after the ashing treatment as described above, a sufficient cleaning effect is produced even if the foaming agent component and the foaming auxiliary component do not contain an oxidizing agent. . In the cleaning method, when an oxidizing agent is not used, the generation of an oxide film on the substrate is more preferably suppressed. The ashing process can be performed by a known method, for example, a method using a plasma gas.
Further, the above cleaning method may be repeatedly performed on the same substrate. For example, an effect that is greater than or equal to a single cleaning can be obtained by a process such as performing the cleaning twice or more (for example, twice or three times).

(Semiconductor substrate)
As a semiconductor substrate (semiconductor element substrate) to be cleaned in the cleaning process, a semiconductor substrate at any stage in the manufacturing process can be used. A preferable example of the object to be cleaned is a semiconductor substrate provided with a resist (particularly, a resist subjected to ion implantation (ion implantation)) on the surface thereof. In addition, by using the cleaning agent of the present invention, in addition to the resist (or pattern resist), a residue (ashing residue) generated during ashing, a residue (etching residue) generated during etching, and other impurities on the surface. These can be peeled and removed.
In addition to the resist, the semiconductor substrate used in the present invention includes an insulating film such as a silicon oxide film and a silicon nitride film, a tantalum nitride layer (TaN), a titanium nitride layer (TiN), a hafnium oxide layer (HfO ₂ ), It may have a lanthanum oxide layer (La ₂ O ₃ ), an aluminum oxide layer (Al ₂ O ₃ ), polysilicon, doped (argon, carbon, neon, arsenic, etc.) silicon, etc. on a part or all of its surface. Good.
The semiconductor substrate refers to a member made of a semiconductor material (for example, a silicon substrate), but is not limited to a plate-shaped substrate, and any shape is included in the “semiconductor substrate” as long as it is a semiconductor material.

  As the resist deposited on the semiconductor substrate to be used, a known resist material is used, and examples thereof include positive type, negative type, and positive / negative type photoresists. Specific examples of the positive resist include vinyl cinnamate, cyclized polyisobutylene, azo-novolak resin, and diazoketone-novolak resin. Specific examples of the negative resist include azide-cyclized polyisoprene, azide-phenol resin, and chloromethyl polystyrene. Furthermore, specific examples of the positive / negative resist include poly (p-butoxycarbonyloxystyrene) type.

(Washing procedure)
In the cleaning method using the cleaning agent of the present invention, an embodiment in which the foaming agent component and the foaming auxiliary component are supplied to the semiconductor substrate is preferable. Although the supply method is not particularly limited, the foaming agent component and the foaming auxiliary component may be simultaneously supplied to the semiconductor substrate (Aspect A). Moreover, after supplying a foaming agent component to a semiconductor substrate, you may supply a foaming adjuvant component after progress for a predetermined time (aspect B). Furthermore, after supplying a foaming auxiliary agent component to a semiconductor substrate, the foaming agent component may be supplied after a predetermined time has passed (Aspect C).

From the point of being excellent in the peelability of the deposit, it is preferable to immerse the semiconductor substrate in either the foaming agent component or the foaming auxiliary component for a predetermined time and add the other (Aspect B or C). In particular, it is more excellent in releasability of deposits, and damage to the substrate and the gate insulating film is further reduced. From the point of immersing the semiconductor substrate in the foaming agent component, adding a foaming auxiliary component (Aspect C) preferable. By immersing the semiconductor substrate in the foaming agent component for a predetermined time, the carbonate adheres in the vicinity of the deposit, so that the generated carbon dioxide gas contributes to the removal and removal of the deposit efficiently.
The immersion time of the semiconductor substrate in the foaming agent component or foaming auxiliary agent component is not particularly limited, but the longer the immersion time, the more the components that are included adhere around the deposit such as resist residue on the semiconductor substrate, and the deposit The removal efficiency is improved. From the viewpoint of improving the peelability of the deposit, it is preferably 10 seconds or longer, and more preferably 30 seconds or longer. In addition, from the point which productivity and an effect are saturated, within 30 minutes are preferable.
The temperature of the foaming agent component or the foaming auxiliary agent component at the time of immersion is not particularly limited, but is preferably 25 to 80 ° C. from the viewpoint that the peelability of the deposit is more excellent and stable foaming is achieved.

When a mixed liquid is produced by adding the other of the foaming agent component or the foaming aid component not selected to either the foaming agent component or the foaming aid component in which the semiconductor substrate is immersed, the component (foaming) As a method of adding an agent component or a foaming auxiliary agent component), it may be added all at once or in divided portions.
In addition, in the said washing | cleaning method, you may add together components (for example, pure water) other than a foaming agent component and a foaming adjuvant component in the range which does not impair the effect of invention.

The temperature of the liquid mixture of the foaming agent component and the foaming auxiliary component (treatment temperature) is not particularly limited, but it is superior in the peelability of deposits, and damage to the substrate and gate insulating film is further reduced. The temperature is preferably controlled so as to be 25 to 80 ° C, more preferably 30 to 75 ° C. If the temperature of the liquid mixture is too high, carbon dioxide gas bubbles may occur instantaneously, and the peelability and handling of the deposit may be impaired. If the temperature of the liquid mixture is too low, the time for removing the deposit will be lost. It may take such a case.
As described above, when adding the foaming aid component (or foaming aid component) to the foaming agent component (or foaming aid component) in which the semiconductor substrate is immersed, the temperature of the mixed solution remains within the above range. It is more preferable to control the addition rate.

  After mixing the foaming agent component and the foaming auxiliary agent component, the semiconductor substrate may be immersed in the mixed solution for a predetermined time if necessary. Although the immersion time is not particularly limited, it is preferably 10 seconds to 5 minutes and more preferably 30 seconds to 3 minutes from the viewpoint of productivity. During immersion of the semiconductor substrate in the mixed solution, the mixed solution may be stirred as necessary.

  After completion of the above treatment, the semiconductor substrate may be taken out from the mixed solution, and a treatment (cleaning step) for washing the surface with water or the like may be performed as necessary.

Through the cleaning method using the two-agent type semiconductor substrate cleaning agent of the present invention, deposits such as ion-implanted resist, which have been difficult to remove and remove by conventional chemicals, are removed from the surface of the semiconductor substrate. Can be peeled off and removed. That is, the two-agent type semiconductor substrate cleaning agent of the present invention can be suitably used as a resist stripping treatment agent for stripping and removing the resist remaining on the semiconductor substrate.
Further, according to the cleaning method using the two-agent type semiconductor substrate cleaning agent of the present invention, unlike the case of using a conventional cleaning chemical SPM solution, the semiconductor substrate itself (for example, a silicon substrate) or the semiconductor substrate Suppresses the influence of corrosion on metal wiring such as aluminum deposited on the surface of silicon, and gate insulating films such as titanium nitride layer (TiN), hafnium oxide layer (HfO ₂ ), and lanthanum oxide layer (La ₂ O ₃ ). be able to.

Moreover, it is preferable that the washing | cleaning process implemented by the washing | cleaning method using the cleaning agent for 2 agent type semiconductor substrates of this invention mentioned above is contained in the manufacturing method of a semiconductor element. Specifically, it is a method for manufacturing a semiconductor element comprising a cleaning step using the above-described foaming agent component and foaming auxiliary component.
This cleaning method can be used for cleaning a semiconductor substrate with a very fine wiring width, which could not be applied with a conventional cleaning agent, and is less damaging to a high-k film. It can be suitably used for manufacturing electronic parts such as memory and CPU. Furthermore, it can also be suitably used for manufacturing a semiconductor substrate using a porous material that is susceptible to damage such as Ultra-low-k, which is being developed as a next-generation insulating film.

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

(Preparation of sample 1)
A general-purpose resist (248 nm KrF resist) was applied on a silicon wafer so that the resist thickness was 3000 mm. Next, the sample coated with this resist was pre-baked (temperature: 200 to 300 ° C.). Thereafter, an ion implantation operation was performed. A sample was prepared using As ions as the ions and a dose of 1E ^{15 to 16} atoms / cm ² .

(Preparation of sample 2)
An Al ₂ O ₃ layer, a TiN layer, an HfO ₂ layer, or an La ₂ O ₃ layer was formed on a silicon wafer so as to have a thickness of 50 mm, and four types of wafers were prepared. The etching rate (EtchingRate: ER) to each film was calculated from the film thickness difference before and after the treatment using each liquid described later.
Practically, the etching rate is preferably less than 5 nm / min, and more preferably less than 1 nm / min.

Surfactants W1 to W9 used in Examples described later are shown below.
In W1, a is 3, b is 5, and c is 3.
In W2, a is 4, 4 is 2, and c is 4.
In W8, a is 5, b is 5, c is 5, d is 5, e is 5, and f is 5.
Further, “30% hydrogen peroxide” in Tables 1 to 9 represents a hydrogen peroxide solution having a concentration of 30% by mass.

<Example A: Examination of acidic compounds (Examples 1 to 19, Comparative Examples 1 to 5)>
Using the foaming agent component and the foaming auxiliary component shown in Table 1 below, the resist peelability, handling property, and influence on the substrate were evaluated.
First, the semiconductor substrate (Sample 1, Sample 2, or untreated silicon wafer) prepared above was immersed in the foaming agent component for a predetermined time (3 minutes). Table 1 shows the pH (expressed as initial pH) of the used blowing agent component.
Next, a foaming assistant component was added to the foaming agent component, and the substrate was immersed in the mixed solution for 2 minutes. Then, the board | substrate was taken out and the following evaluation was implemented. In addition, pH in a liquid mixture is represented in Table 1 as final pH. The obtained results are shown in Table 1.
In addition, the process temperature in Table 1 means the temperature in a liquid mixture, and is synonymous also in Tables 2-9 mentioned later.

The resist peelability was evaluated according to the following criteria. For practical purposes, it is necessary not to be x.
“◎◎◎: When the resist remains on the surface of the substrate (area: 3.0 × 3.0 μm) observed with a microscope is less than 5%”
“◎: When the resist remains on the surface of the substrate (area: 3.0 × 3.0 μm) observed with a microscope is 5% or more and less than 10%”
“A: When the resist remains on the substrate surface (area: 3.0 × 3.0 μm) observed with a microscope is 10% or more and less than 30%”
“O: When the resist remains on the substrate surface (area: 3.0 × 3.0 μm) observed with a microscope is 30% or more and less than 50%”
“△: When the portion where the resist remains on the surface of the substrate (area: 3.0 × 3.0 μm) observed with a microscope is 50% or more and less than 80%”
“×: When the resist remains on the substrate surface (area: 3.0 × 3.0 μm) observed with a microscope is 80% or more”
Handling was evaluated according to the following criteria.
“◎”: No problem foaming “◯”: Slight foaming “Δ”: Slightly foaming “×”: Severe foaming at a level that is difficult to use in practice is observed.

The values described in the column “Doped Si-loss” in Table 1 indicate the loss thickness (thickness shaved by cleaning) on the wafer surface when using an untreated silicon wafer in Example A as ICP-MS ( This is a value (nm) converted to a film thickness after measurement with an inductively coupled plasma mass spectrometer (manufactured by SHIMADZU). Practically, the value is preferably less than 1.0 nm.
Moreover, the value described in the column “Ox growth” in Table 1 indicates the thickness of the silicon oxide layer formed on the wafer surface when an untreated silicon wafer is used in Example A. Ellipsometry (J. A. Value (nm) measured by WASEL, VASE). Practically, the value is preferably less than 1.0 nm.

  In Table 1, “ND” means that the etching rate is almost zero. In Table 1, “TMAH” used in the foaming agent component represents tetramethylammonium hydroxide.

From Table 1, it was confirmed that when various acidic compounds were used, resist peelability and handling properties that were practically satisfactory were obtained. Further, as can be seen from the results using Sample 2, in the cleaning agent of the present invention, almost no etching action was observed on the Al ₂ O ₃ layer, TiN layer, HfO ₂ layer, and La ₂ O ₃ layer. It was confirmed that no damage was caused to the other layers. Further, it was found that the surface of the substrate was scraped and the generation of a silicon oxide layer was suppressed (each less than 0.1 nm).

On the other hand, as shown in Comparative Examples 1 and 2, when a conventionally known SPM or the like was used as the cleaning liquid, the resist was peeled, but the handling property was impaired. In addition, it was confirmed that etching progressed with respect to the Al ₂ O ₃ layer, TiN layer, HfO ₂ layer, and La ₂ O ₃ layer, and each layer was damaged. Furthermore, it was confirmed that the substrate surface was scraped and a silicon oxide layer was generated.

  Further, as shown in Comparative Example 4 in which the foaming agent component containing carbonate is not used and Comparative Example 5 in which the foaming auxiliary component containing acidic compound is not used, when one component is missing, resist stripping is performed. It was confirmed that it was inferior in sex.

  Furthermore, as shown in Comparative Example 6, when the pH of the mixture of the foaming agent component and the foaming auxiliary component is 7.5 or more, foaming in the mixed solution is not confirmed, and the resist peelability is also inferior. Was confirmed.

<Example B: Examination of carbonate (Examples 20 to 25)>
Using the foaming agent component and foaming aid component shown in Table 2 below, washing was performed in the same procedure as in Example A, and various evaluations were performed. In Table 2, the initial pH represents the pH of the foaming agent component, and the final pH represents the pH of the mixed solution of the foaming agent component and the foaming auxiliary component.

  From Table 2, when the cleaning method of the present invention was carried out using various carbonates, it was confirmed that practically satisfactory resist stripping properties and handling properties were obtained. Moreover, there was almost no etching to various metal layers, and there was almost no influence on a silicon wafer.

<Example C: Content examination of various used components (Examples 26 to 35)>
Using the foaming agent component and foaming auxiliary component shown in Tables 3 to 5 below, washing was performed in the same procedure as in Example A, and various evaluations were performed. In Tables 3 to 5, the initial pH represents the pH of the foaming agent component, and the final pH represents the pH of the mixed solution of the foaming agent component and the foaming auxiliary component.

  As shown in Table 3, Table 4, and Table 5, it was confirmed that the desired effect was obtained even when the amounts of carbonate, TMAH, and acidic compound used were changed.

<Example D: Content examination of oxidizing agent (Examples 36 to 38)>
Using the foaming agent component and the foaming auxiliary component shown in Table 6 below, washing was performed in the same procedure as in Example A, and various evaluations were performed. In Table 6, the initial pH represents the pH of the foaming agent component, and the final pH represents the pH of the mixed solution of the foaming agent component and the foaming auxiliary component.

  As shown in Table 6, it was confirmed that the desired effect was obtained even when the amount of the oxidizing agent used was changed. In particular, it has been found that the resist peelability is improved by increasing the content of the oxidizing agent.

<Example E: Investigation of surfactant (Examples 39 to 49)>
Using the foaming agent component and foaming auxiliary component shown in Table 7 below, washing was performed in the same procedure as in Example A, and various evaluations were performed. In Table 7, the initial pH represents the pH of the foaming agent component, and the final pH represents the pH of the mixed solution of the foaming agent component and the foaming auxiliary component.
The evaluation in the “Re-adhesion” column in Table 7 was evaluated according to the following criteria.
“◯”: When the surface of the wafer after processing is observed with an optical microscope, there is no reattachment of the peeled material.
“Δ”: When the wafer surface after processing was observed with an optical microscope, a slight reattachment of the peeled material was confirmed.
"X": When the wafer surface after processing was observed with an optical microscope, reattachment of many peeled materials was confirmed.

As shown in Table 7, it was found that the desired effect was obtained even when various surfactants were used in the cleaning method of the present invention.
In particular, it was confirmed that a polyoxyalkylene type nonionic surfactant (particularly, a surfactant represented by the general formula (1)) produces an excellent effect in handling properties.

<Example F: Content examination of surfactant (Examples 50 to 53)>
Using the foaming agent component and foaming auxiliary component shown in Table 8 below, washing was performed in the same procedure as in Example A, and various evaluations were performed. In Table 8, the initial pH represents the pH of the foaming agent component, and the final pH represents the pH of the mixed solution of the foaming agent component and the foaming auxiliary component.

  As shown in Table 8, in the cleaning method of the present invention, it was found that the desired effect was obtained even when the amount of various surfactants used was changed.

<Example G: Application of pretreatment (Examples 54 to 55)>
Using the foaming agent component and the foaming auxiliary component shown below, washing was performed in the same procedure as in Example A, and various evaluations were performed. In Table 9, the initial pH represents the pH of the foaming agent component, and the final pH represents the pH of the mixed solution of the foaming agent component and the foaming auxiliary component.
In addition, the silicon wafer used this time was a silicon wafer once processed under the following conditions.
Example 54: A silicon wafer provided with a resist ion-implanted by the above-described method is treated with a DMSO solution to remove a bulk layer, and the cured film remaining on the silicon wafer is subjected to the following foaming agent component and foaming. A washing treatment was performed using the auxiliary component.
Example 55: Oxygen is converted into a plasma gas by ultraviolet light, and the ashing treatment is performed on the silicon wafer provided with the resist ion-implanted by the above method using the plasma gas, and the following foaming agent is applied to the residue. Washing was performed using the ingredients and the foaming aid ingredient.

  As can be seen from Table 9, it was confirmed that when the ashing treatment was performed before the cleaning step, the resist peelability was further improved.

Claims (12)

A cleaning agent for a two-part type semiconductor substrate having a foaming agent component and a foaming auxiliary agent component, which are mixed and used when cleaning a semiconductor substrate,
The blowing agent component contains carbonate;
The foaming auxiliary component contains an acidic compound,
Furthermore, the foaming agent component and / or the foaming aid component contains a surfactant,
A cleaning agent for a two-component semiconductor substrate, wherein a pH of a mixed solution of the foaming agent component and the foaming auxiliary component is less than 7.5.   The cleaning agent for a two-component semiconductor substrate according to claim 1, wherein the surfactant is a nonionic surfactant.   The carbonate is ammonium carbonate, ammonium bicarbonate, sodium bicarbonate, sodium carbonate, potassium carbonate, potassium bicarbonate, cesium carbonate, lanthanum carbonate, lithium carbonate, magnesium carbonate, manganese carbonate, nickel carbonate, strontium carbonate, aminoguanidine carbonate The cleaning agent for a two-component semiconductor substrate according to claim 1 or 2, wherein the cleaning agent is a carbonate selected from the group consisting of a salt and guanidine carbonate.   The acidic compound is sulfuric acid, nitric acid, boric acid, phosphoric acid, formic acid, acetic acid, propionic acid, benzoic acid, glycolic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid , Maleic acid, phthalic acid, malic acid, tartaric acid, citric acid, lactic acid, glycine, alanine, aspartic acid, glutamic acid, aminomethanesulfonic acid, taurine, benzenesulfonic acid, toluenesulfonic acid, methanesulfonic acid, ethanesulfonic acid, and The cleaning agent for 2 agent type semiconductor substrates in any one of Claims 1-3 which is a compound chosen from the group which consists of sulfamic acid.   The cleaning agent for 2 agent type semiconductor substrates in any one of Claims 1-4 whose density | concentration of the said carbonate in the said liquid mixture is 0.1-30 mass%.   Furthermore, the cleaning agent for 2 agent type semiconductor substrates in any one of Claims 1-5 in which the said foaming agent component and / or the said foaming adjuvant component contain an oxidizing agent.   The cleaning agent for 2 agent type semiconductor substrates in any one of Claims 1-6 whose said surfactant is a polyoxyalkylene type nonionic surfactant. The two-component semiconductor substrate according to any one of claims 1 to 7, wherein the surfactant is a polyoxyalkylene type nonionic surfactant represented by the general formula (2) or the general formula (3). Washing soap.
  HO- (EO) _x -(PO) _y -(EO) _z -H General formula (2)
  HO- (PO) _x -(EO) _y -(PO) _z -H General formula (3)
(In general formula (2) and general formula (3), EO represents an oxyethylene group and PO represents an oxypropylene group. X, y and z each independently represents an integer of 1 or more.) The two-component semiconductor substrate cleaning agent according to any one of claims 1 to 8 , wherein the pH of the mixed solution is less than 7. The two-component type semiconductor substrate cleaning agent according to any one of claims 1 to 9 , wherein a content of the surfactant in the foaming agent component or the foaming auxiliary agent component is 0.0001 to 10 % by mass. The content of the oxidizing agent in the blowing agent component or the blowing aid component is 0.01 to 20 wt%, 2 dosage semiconductor substrate cleaning agent according to any of claims 6-10. The cleaning agent for a two-component semiconductor substrate according to any one of claims 1 to 11 , wherein the foaming agent component has a pH of 7.5 to 12 .