JP2003088817A - Method for cleaning surface of substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for highly efficiently cleaning a substrate, by which both of a particle-shaped contaminant and a metallic contaminant can be removed in a short time while extremely reducing the occurrence of such a problem that the removed contaminants are stuck to the substrate again and the processed dimensions of the substrate are deformed by etching. SOLUTION: This method comprises at least two following steps (1) and (2). The second cleaning step (2) is carried out after the first cleaning step (1). In the first cleaning step (1), the surface of the substrate is cleaned by using a complex forming agent-containing alkaline detergent. In the second cleaning step (2) the substrate is cleaned by using another detergent having 0.03-3 wt.% hydrofluoric acid content C for <=45 seconds cleaning time t while satisfying the inequality: 0.25<=tC<1.29> <=5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning method for cleaning the surface of a device substrate in a process of manufacturing a semiconductor device, a display device or the like. More specifically, the present invention resides in a method for cleaning a substrate surface, which removes both metal and fine particles (particles) that are contaminants on the substrate in a short time to highly clean the substrate surface.

[0002]

2. Description of the Related Art Microprocessor, memory, CC
In the manufacturing process of semiconductor devices such as D and flat panel display devices such as TFT liquid crystal, patterns and thin films are formed on the substrate surface of silicon (Si), silicon oxide (SiO ₂ ), glass, etc. with submicron dimensions. ing. And when manufacturing these, it is a very important subject to reduce a slight amount of contamination on the surface of the substrate in each step of manufacturing.

Among the pollutions, particularly metal pollution and particle pollution lowers the electrical characteristics and yield of the device. Therefore, it is necessary to reduce the pollution as much as possible in the process where the pollution occurs and then move the substrate to the next process. There is. To remove the contamination, it is common practice to clean the surface of the substrate with a cleaning agent. In recent years, further improvement in production efficiency has been required in device manufacturing, such as increasing the number of substrates processed per unit time. In the manufacture of substrates with devices that are becoming more and more miniaturized and highly integrated, the substrate surface There is a demand for a cleaning method which is excellent in removing both metal contamination and particle contamination, and which rapidly and highly cleans the substrate surface.

It is generally known that cleaning with an alkaline solution is effective for removing particle contamination.
An alkaline aqueous solution such as an aqueous ammonia solution, an aqueous potassium hydroxide solution, or an aqueous tetramethylammonium hydroxide solution is used for cleaning the surface of a Si substrate or a SiO ₂ substrate for a semiconductor device or a glass substrate for a display device. Further, cleaning with a cleaning agent composed of ammonia, hydrogen peroxide, and water (referred to as "SC-1 cleaning agent" or "APM cleaning agent") (referred to as "SC-1 cleaning" or "APM cleaning") is also widely used. .

On the other hand, it is known that cleaning with an acidic aqueous solution is effective for removing metal contamination. To clean the surface of Si or SiO ₂ substrates for semiconductor devices or glass substrates for display devices, acid such as hydrochloric acid, nitric acid, sulfuric acid or hydrofluoric acid diluted with water is used as a cleaning agent. There is. Cleaning with a cleaning agent composed of hydrochloric acid, hydrogen peroxide and water (referred to as "SC-2 cleaning agent" or "HPM cleaning agent") (referred to as "SC-2 cleaning" or "HPM cleaning") is also widely used. .

In order to remove both particle contamination and metal contamination on the surface of the substrate, cleaning is performed in a plurality of steps by combining these cleanings. A method for cleaning the surface of semiconductor device substrates by so-called RCA cleaning (Kern and Puo), in which SC-1 cleaning removes particle contamination and SC-2 cleaning subsequently removes metal contamination.
tinen: RCA Review, pp.187-206, June (1970)) is widely used. Further, in order to remove metal contamination that is chemically bonded to Si or SiO _{2 on the} surface of the substrate or a small amount of metal contamination taken into the surface layer of the substrate, the hydrofluoric acid content is about 0.25 to 1% by weight. With the dilute hydrofluoric acid aqueous solution (hereinafter, may be simply referred to as “dilute hydrofluoric acid”),
It is effective to etch the surface layer of the substrate. Particularly, aluminum (Al) and copper (Cu) are S on the substrate surface.
Since it is easy to react with i or SiO ₂ to form a strong chemical bond and is easily taken into the vicinity of the surface layer of the substrate, the most effective method for cleaning the substrate surface is to etch the surface layer of the substrate and remove them. It has recently been shown to be effective (Morinaga et al., The ElectrochemicalSoc
iety Proceeding Series PV99-36, pp.585-592, Pennin
gton, NJ (2000) etc.). Therefore, after SC-1 cleaning, after SC-2 cleaning, or between SC-1 cleaning and SC-2 cleaning, cleaning with dilute hydrofluoric acid is performed, and cleaning is performed in a total of 3 step stages to achieve high cleanliness. It is possible to obtain a smooth surface. The cleaning method consisting of these two steps or three steps generally requires 1 to 15 minutes for the cleaning step per step, and thus requires several tens of minutes in total.

There are two typical types of devices for cleaning the surface of the device substrate. One is a batch-type cleaning device that normally cleans a plurality of substrates housed in a cassette by immersing them in a cleaning tank containing a cleaning agent. On the other hand, one substrate is attached to the holder, and usually the substrate is rotated (for example, if the substrate has a disk shape, it is rotated in the circumferential direction).
This is a single-wafer cleaning device that applies a cleaning agent to the surface of the substrate while performing the cleaning. The batch type cleaning device has a large number of substrates to be processed per unit time, but the device is large, and the contamination detached from the device formation surface of the substrate or its back surface reattaches to another device formation surface, so-called contamination between substrates. There are problems that re-adhesion (cross contamination) occurs and a large amount of cleaning agent is required even when only one sheet is desired to be cleaned.

On the other hand, the single-wafer cleaning apparatus is small in size and has no cross-contamination, but it has a problem that the number of substrates processed per unit time is small because it is cleaned one by one.

[0009]

In the conventional method for cleaning the surface of the substrate, as described above, SC-1 cleaning and SC-cleaning are performed.
The substrate surface was highly cleaned by a cleaning method having a plurality of steps, including 2 cleaning and further cleaning with dilute hydrofluoric acid. Therefore, there is a problem that the cleaning time is long and the production efficiency is poor. Particularly, in the single-wafer cleaning apparatus for cleaning the substrates one by one, the number of substrates processed per unit time is small, so that a large number of cleaning apparatuses are required, which is disadvantageous in terms of cost.

Further, in cleaning with dilute hydrofluoric acid, it is usually 0.5% by weight.
Since the surface of the substrate (SiO ₂ film, etc.) is etched by 10 angstroms (Å) or more during the cleaning treatment for 1 to 5 minutes using a hydrofluoric acid aqueous solution, the processing dimensional accuracy of the device on the substrate surface In recent years,
Various problems are emerging. It is expected that this problem will rapidly become apparent in the future as devices become finer and gate oxide films become thinner. In addition, particles adhere to the hydrophobic Si surface exposed by etching to contaminate (generally particles are likely to adhere to the hydrophobic surface), and water droplets remaining on the hydrophobic surface may be stained. There is also a problem such as contamination, so-called watermarking.

In order to suppress such etching of SiO ₂ , the cleaning time is the same as the conventional one, but the concentration of hydrofluoric acid is extremely reduced, for example, an extremely small amount of hydrofluoric acid of about 10 ppm by weight is added to pure water. A cleaning method has also been proposed in which the surface of the substrate is cleaned with an aqueous solution of hydrofluoric acid (Japanese Patent Laid-Open No. Hei 3).
-190130 gazette etc.). However, in such a cleaning method, since the concentration of hydrofluoric acid is extremely low, it takes about 5 minutes just to wash with the hydrofluoric acid aqueous solution, and the production efficiency is still low. In addition, when this method is applied to a single-wafer cleaning device, a large amount of cleaning agent is required, so a large amount of acid waste liquid is generated, and this disposal becomes a problem.

[0012]

The present invention has been made in order to solve the above-mentioned problems, and in the manufacturing process of semiconductor devices, display devices, etc.,
An object of the present invention is to provide a highly efficient substrate cleaning method that removes both particle contamination and metal contamination from a device substrate in a short time, and significantly reduces processing redeposition and processing dimensional changes due to etching. It is what

As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention found that, first of all, rather than washing for a long time with an extremely dilute aqueous solution of hydrofluoric acid as described above, As described above, it has been found that, more specifically, it is possible to obtain a higher metal contamination removing effect by washing with a hydrofluoric acid aqueous solution of 0.03 wt% or more for a specific time or less. Furthermore, in cleaning with a hydrofluoric acid aqueous solution, when the concentration of hydrofluoric acid (% by weight) and the cleaning time (seconds) are expressed in a specific relationship, sufficient removal of metal contamination and processing dimensional change due to etching (described above) It was found that both problems can be solved.

As a result of further studies, a step (1) of cleaning the substrate surface with an alkaline cleaner containing a complexing agent
And the cleaning step with the hydrofluoric acid aqueous solution described above, that is, when cleaning the substrate surface for a specific time or less using a cleaning agent with a hydrofluoric acid content above a specific concentration, specify the concentration of the hydrofluoric acid in the cleaning agent and the cleaning time. By combining the steps (2) which are related to each other in this order, it is possible to remove both the particle contamination and the metal contamination on the substrate surface in an extremely short time. The present invention has been completed by finding that it has an excellent effect that there are few problems.

That is, the gist of the present invention resides in a substrate surface cleaning method including at least the following step (1) and step (2), and performing step (2) after performing step (1). Step (1) A cleaning step of cleaning the substrate surface with a complexing agent-containing alkaline cleaning agent. Step (2) A cleaning agent having a hydrofluoric acid content C (% by weight) of 0.03 to 3% by weight is used, a cleaning time t (seconds) of the substrate with the cleaning agent is 45 seconds or less, and C t is 0.25
≤ tC ^1.29 ≤ 5 cleaning process.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. (A) Alkaline detergent (A-1) Alkaline component The alkaline detergent used in step (1) of the present invention is an alkaline aqueous solution containing an alkaline component and having a pH value of more than 7. The alkaline component of the solution is not particularly limited, but representative examples thereof include ammonium hydroxide (aqueous ammonia solution) and organic alkali. Examples of the organic alkali include amines such as quaternary ammonium hydroxide, amines and amino alcohols. As the quaternary ammonium hydroxide, those having an alkyl group having 1 to 4 carbon atoms and / or a hydroxyalkyl group are preferable. Examples of the alkyl group include an alkyl group having 1 to 10 carbon atoms such as methyl group, ethyl group, propyl group and butyl group, and examples of the hydroxyalkyl group include hydroxymethyl, hydroxyethyl, hydroxypropyl, hydroxybutyl and the like having 1 carbon atom. And hydroxyalkyl groups of 10 to 10.

Specific examples of such a quaternary ammonium hydroxide include tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, trimethyl (hydroxyethyl) ammonium hydroxide (common name: choline), triethyl (hydroxy). Ethyl) ammonium hydroxide and the like. Other amines include ethylenediamine, monoethanolamine, trimethanolamine and the like.

Further, hydroxides of alkali metals or alkaline earth metals such as sodium hydroxide, potassium hydroxide and calcium hydroxide, and alkaline salts such as sodium hydrogen carbonate and ammonium hydrogen carbonate are also used. Among the above-mentioned alkaline components, ammonium hydroxide, tetramethylammonium hydroxide (TMAH), trimethyl (hydroxyethyl) are used as the alkaline components for the reasons such as cleaning effect, less residual metal, economical efficiency, and stability of the cleaning agent. Ammonium hydroxide (common name: choline) and the like are preferable, and ammonium hydroxide is particularly preferable. These alkaline components may be used alone or in any combination of two or more. The concentration of the alkaline component in the detergent may be appropriately selected, but is generally 0.001 to 5% by weight, and particularly preferably 0.002 to 1% by weight. If the concentration of the alkaline component is too low, the effect of removing contaminants, which is the object of the present invention, cannot be obtained. On the contrary, if the concentration is too high, a high effect corresponding to the high concentration cannot be expected, which is not economically disadvantageous, and the risk of damaging the substrate surface by etching increases, which is not preferable.

Among the complexing agent-containing alkaline detergents used in the present invention, among others, there is little residual metal, economical efficiency,
For reasons such as detergent stability, ammonium hydroxide,
Tetramethylammonium hydroxide (TMAH),
Trimethyl (hydroxyethyl) ammonium hydroxide (common name: choline) and the like are preferable, and ammonium hydroxide is particularly preferable.

(A-2) Complexing agent Since the alkaline detergent used in the present invention contains a complexing agent, an extremely highly clean surface with further reduced metal contamination on the substrate surface can be obtained, which is preferable. Any conventionally known complexing agent can be used in the present invention. When selecting a complexing agent, the contamination level of the substrate surface, the type of metal,
It may be selected by comprehensively judging from the cleanliness level required for the surface of the substrate, the cost of the complexing agent, the chemical stability, etc. For example, the following may be mentioned. (1) Compounds having nitrogen as a donor atom and a carboxyl group and / or phosphonic acid group, for example, amino acids such as glycine; iminodiacetic acid, nitrilotriacetic acid, ethylenediaminetetraacetic acid [EDTA], trans-1,2-diamino Cyclohexane tetraacetic acid [Cy
DTA], diethylenetriamine pentaacetic acid [DTPA],
Nitrogen-containing carboxylic acids such as triethylenetetramine 6-acetic acid [TTHA]; ethylenediaminetetrakis (methylenephosphonic acid) [EDTPO], nitrilotris (methylenephosphonic acid) [NTPO], propylenediaminetetra (methylenephosphonic acid) [PDTMP], etc. Examples thereof include nitrogen-containing phosphonic acids. (2) A compound having an aromatic hydrocarbon ring and having two or more OH groups and / or O ⁻ groups directly bonded to the carbon atoms constituting the ring, for example, phenols such as catechol, resorcinol, Tyrone, and the like. The derivative etc. are mentioned. (3) Compound (3-1) having both the structures of (1) and (2) above: ethylenediaminedioltohydroxyphenylacetic acid [EDDHA] and its derivatives, for example, ethylenediaminedioltohydroxyphenylacetic acid [EDDHA], ethylenediamine-N, N'-bis [(2-hydroxy-5-methylphenyl) acetic acid]
[EDDHMA], ethylenediamine-N, N'-bis [(2-hydroxy-5-chlorophenyl) acetic acid] [E
DDHCA], ethylenediamine-N, N'-bis [(2-hydroxy-5-sulfophenyl) acetic acid] [E
Aromatic nitrogen-containing carboxylic acids such as DDHSA]; ethylenediamine-N, N'-bis [(2-hydroxy-5-
Methylphenyl) phosphonic acid], ethylenediamine-
Examples thereof include aromatic nitrogen-containing phosphonic acids such as N, N'-bis [(2-hydroxy-5-phosphophenyl) phosphonic acid]. (3-2) N, N'-bis (2-hydroxybenzyl)
Ethylenediamine-N, N'-diacetic acid [HBED] and its derivatives such as N, N'-bis (2-hydroxybenzyl) ethylenediamine-N, N'-diacetic acid [HBED], N,
N'-bis (2-hydroxy-5-methylbenzyl) ethylenediamine-N, N'-diacetic acid [HMBED],
N, N'-bis (2-hydroxy-5-chlorobenzyl) ethylenediamine-N, N'-diacetic acid and the like can be mentioned. (4) Other amines such as ethylenediamine, 8-quinolinol and o-phenanthroline; carboxylic acids such as formic acid, acetic acid, oxalic acid and tartaric acid; hydrohalic acid such as hydrofluoric acid, hydrochloric acid, hydrogen bromide and hydrogen iodide Or salts thereof; phosphoric acid,
Examples thereof include oxo acids such as condensed phosphoric acid and salts thereof.

These complexing agents may be in the form of acid or may be in the form of salt such as ammonium salt. Among the complexing agents mentioned above, ethylenediaminetetraacetic acid [EDT] is used because of its cleaning effect and chemical stability.
A], nitrogen-containing carboxylic acids such as diethylenetriamine pentaacetic acid [DTPA]; nitrilotris (methylenephosphonic acid) [NTPO], ethylenediaminetetrakis (methylenephosphonic acid) [EDTPO], propylenediaminetetra (methylenephosphonic acid) [PDTMP], etc. Nitrogen-containing phosphonic acids; ethylenediamine diorthohydroxyphenylacetic acid [EDDHA] and its derivatives; N,
N'-bis (2-hydroxybenzyl) ethylenediamine-N, N'-diacetic acid [HBED] and the like are preferable.

Among them, from the viewpoint of cleaning effect, elenediaminedioltohydroxyphenylacetic acid [EDDHA], ethylenediamine-N, N'-bis [(2-hydroxy-5)
-Methylphenyl) acetic acid] [EDDHMA], diethylenetriamine 5 acetic acid [DTPA], ethylenediamine 4
Acetic acid [EDTA], nitrilotris (methylenephosphonic acid) [NTPO], propylenediaminetetra (methylenephosphonic acid) [PDTMP] are preferable.

These complexing agents may be used alone or in any combination of two or more. The concentration of the complexing agent in the cleaning agent may be arbitrarily selected depending on the type and amount of contaminant metal impurities and the level of cleanliness required for the substrate surface, but generally 1 to 10000 ppm by weight, and particularly 5 to 5 ppm by weight. 1000
Weight ppm, especially 10 to 200 weight ppm is preferred.
If the concentration of the complexing agent is too low, the effect of removing the stains and preventing the adhesion by the complexing agent cannot be obtained. On the contrary, if the concentration is too high, the high effect corresponding to the high concentration cannot be expected, which is economically disadvantageous, and the risk that the complexing agent may adhere to the substrate surface and remain after the surface treatment increases. It is not preferable.

The complexing agent is usually 1 to several thousand ppm of iron (Fe) or zinc (Zn) in commercially available reagents.
It may contain metal impurities such as. Therefore, the complexing agent used in the present invention may be a source of metal contamination. These metal impurities exist in a stable complex with the complexing agent immediately after the surface treating agent is prepared, but the complexing agent decomposes during long-term use of the surface treating agent. However, there is a risk that the metal will be released and adhere to the surface of the substrate. Therefore, it is preferable that the complexing agent used in the present invention removes metallic impurities such as Fe, Al, and Zn contained in advance so that the content of each is 5 ppm or less, particularly 2 ppm.
The following is preferable. In order to obtain such a purified complexing agent, for example, after dissolving the complexing agent in an acidic or alkaline aqueous solution, insoluble impurities are removed by filtration separation or the like, and neutralization is performed again to form crystals of the complexing agent. It may be purified by a method such as precipitation and separation. (A-3) Other additives such as surfactants

The alkaline detergent used in the present invention may be appropriately blended with an oxidizing agent such as hydrogen peroxide, ozone or oxygen. When cleaning the surface of a bare silicon substrate (silicon substrate having no oxide film) in the step of cleaning a semiconductor device substrate, the etching and surface roughness of the substrate can be suppressed by mixing an oxidizing agent. When hydrogen peroxide is contained in the alkaline detergent used in the present invention, the concentration of hydrogen peroxide in the whole detergent solution is usually 0.001 to 5% by weight, preferably 0.01 to 1% by weight. Used to be in range.

Further, it is preferable that the alkaline detergent used in the present invention further contains a surfactant because the removal property of particle contamination and organic contamination on the substrate surface is improved. Any conventionally known surfactant can be used. When selecting a surfactant, make a comprehensive judgment based on the contamination level of the substrate surface, the type of particles and organic contaminants, the cleanliness level required for the substrate surface, the surfactant cost, chemical stability, etc. Good. Examples of the surfactant include anionic, cationic, amphoteric and nonionic surfactants. Among them, anionic, amphoteric and nonionic surfactants are preferable. Anionic surfactants are particularly preferable. These surfactants may be used alone or in combination of two or more different kinds. Above all, a combination of an anionic surfactant and a nonionic surfactant is preferable from the viewpoint of the effect of cleaning stains.

As the anionic surfactant, carvone is used.
Acid type, sulfonic acid type, sulfuric acid ester type, phosphoric acid ester
Amino acid type, betaine as amphoteric surfactant
As nonionic surfactants such as molds, polyethylene
Examples include glycol type and polyhydric alcohol type. A
Among the nonionic surfactants, sulfonic acid type (-SO₃−
Group), sulfate ester type (-OSO₃−) Is preferred
Good Specifically -SO₃-Group or -OSO ₃-Low
Compounds having at least one are preferred, these are alone
It may be used, or two or more kinds may be appropriately combined and used.
Yes.

Examples of the surfactant having a —SO ₃ — group include the following compounds (1) to (3). Alkyl sulfonic acid type compounds Examples of the alkyl sulfonic acid type compounds include compounds represented by the following formula (1).

[0029]

[Chemical 1] RSO₃X ... Formula (1) (In the formula, R is an alkyl group, preferably having 8 to 20 carbon atoms.
Alkyl group, X is hydrogen, cation atom or cation source
Indicates a squad. ) Examples of the alkyl sulfonic acids include C₈H₁₇SO₃
H and its salt, C₉H_{1 9}SO₃H and its salt, C_TenH_{twenty one}S
O₃H and its salt, C₁₁H_{twenty three}SO₃H and its salt, C₁₂H
_{twenty five}SO₃H and its salt, C₁₃H₂₇SO₃H and its salt, C
₁₄H₂₉SO₃H and its salt, C₁₅H₃₁SO₃H and its
Salt, C₁₆H₃₃SO₃H and its salt, C₁₇H ₃₅SO₃H and
Its salt, C₁₈H₃₇SO₃H and its salts, etc.
It

Alkylbenzene Sulfonic Acid Compounds Examples of the alkylbenzene sulfonic acid compounds include compounds represented by the following formula (2).

[0031]

R-ph-SO ₃ X Formula (2) (wherein R is an alkyl group, preferably an alkyl group having 8 to 20 carbon atoms, X is hydrogen, a cation atom or a cation atom group, and ph is phenylene. Examples of the alkylbenzene sulfonic acids include dodecylbenzene sulfonic acid and salts thereof. Alkylnaphthalenesulfonic acid-based compound Examples of the alkylnaphthalenesulfonic acid-based compound include compounds represented by the following formula (3).

[0032]

[Chemical 3]

(In the formula, R ¹ and R ² are each an alkyl group,
Preferably, an alkyl group having 1 to 10 carbon atoms, X represents hydrogen, a cation atom or a cation atom group. m and n each represent an integer of 0-4. However, 1 ≦ m + n ≦ 7, preferably 1 ≦ m + n ≦ 4. ) Examples of the alkylnaphthalene sulfonic acid compounds include dimethylnaphthalene sulfonic acid and salts thereof.

Methyl tauric acid compound As the methyl tauric acid compound, a compound represented by the following formula (4) can be mentioned.

[0035]

[Chemical 4]       RCON (CH₃) CH₂CH₂SO₃X ... Formula (4) (In the formula, R is a hydrocarbon group, preferably C_nH_{2n + 1}, C_nH
_2n-1, C_nH_2n-3Or C_nH_2n-5Saturated / unsaturated carbonization of
Hydrogen group, X is hydrogen, cation atom or cation atom group
Indicates. n is usually 8 to 20, preferably 13 to 17
Represents an integer. N, which is the number of carbon atoms in the hydrocarbon group, is too small
And the ability to remove adhered particles tends to decrease. ) Examples of the methyl tauric acid compound include C₁₁H_{twenty three}CO
N (CH₃) CH₂CH ₂SO₃H and its salt, C₁₃H₂₇C
ON (CH₃) CH₂CH₂SO₃H and its salt, C₁₅H₃₁
CON (CH₃) CH₂CH₂SO₃H and its salt, C₁₇H
₃₅CON (CH ₃) CH₂CH₂SO₃H and its salt, C₁₇
H₃₃CON (CH₃) CH₂CH₂SO₃H and its salt, C
₁₇H₃₁CON (CH₃) CH₂CH₂SO₃H and its salt,
C₁₇H₂₉CON (CH₃) CH₂CH₂SO₃H and its salt
And so on.

Alkyl diphenyl ether disulfonic acid type compounds Examples of the alkyl diphenyl ether disulfonic acid type compounds include compounds represented by the following formula (5).

[0037]

Embedded image _{R-ph (SO 3 X)} -O-ph-SO 3 X ... (5) (wherein, R is an alkyl group, preferably an alkyl group having 8 to 20 carbon atoms, X is hydrogen, a cation An atom or a cation atomic group, and ph represents a phenylene group.) Examples of the alkyldiphenyletherdisulfonic acid compound include nonyldiphenyletherdisulfonic acid and salts thereof, dodecyldiphenyletherdisulfonic acid and salts thereof, and the like.

Sulfosuccinic acid diester compound As the sulfosuccinic acid diester compound, a compound represented by the following formula (6) can be mentioned.

[0039]

Embedded image R—O—CO—CH ₂ — (R—O—CO—) CH—SO ₃ X Formula (6)

(In the formula, R represents hydrogen or an alkyl group, preferably an alkyl group having 4 to 20 carbon atoms, and X represents hydrogen, a cation atom or a cation atom group.) Examples of the sulfosuccinic acid diesters include di- Two
-Ethylhexyl sulfosuccinic acid and its salt, lauryl sulfosuccinic acid and its salt, etc. are mentioned. [alpha] -Olefin sulfonic acid compound As the [alpha] -olefin sulfonic acid compound, a mixture of a compound represented by the following formula (7) and a compound represented by the following formula (8) can be mentioned.

[0041]

Embedded image RCH═CH (CH ₂ ) _m SO ₃ X ... Formula (7) RCH ₂ CH (OH) (CH ₂ ) _n SO ₃ X ... Formula (8) (In the formula, R is an alkyl group, preferably Alkyl group having 4 to 20 carbon atoms, X is hydrogen, a cation atom or a cation atomic group, m is an integer of 1 to 10, n is an integer of 1 to 10.) Naphthalenesulfonic acid condensate Naphthalenesulfonic acid condensation Examples of the product include β-naphthalenesulfonic acid formalin condensate and salts thereof.

Fluorine-based surfactants in which hydrogen of the alkyl group or hydrocarbon group of the surfactants represented by the above-mentioned is substituted with fluorine, of these surfactants, in terms of excellent removability of particle contamination, Preferably, an alkylbenzene sulfonic acid type compound, an alkyl diphenyl ether disulfonic acid type compound, and a sulfosuccinic acid diester type compound are used.

Examples of the surfactant having a —OSO ₃ — group include the following compounds (1) to ( ₃ ). Alkyl sulfate ester-based compound Examples of the alkyl sulfate ester-based compound include compounds represented by the following formula (9).

[0044]

ROSO ₃ X Formula (9) (In the formula, R is an alkyl group, preferably an alkyl group having 8 to 20 carbon atoms, and X is hydrogen, a cation atom or a cation atom group.) Alkyl sulfate ester type Examples of the compound include dodecyl sulfate and salts thereof.

Alkyl ether sulfuric acid ester compounds As the alkyl ether sulfuric acid ester compounds, there may be mentioned compounds represented by the following formula (10).

[0046]

Embedded image RO (CH ₂ CH ₂ O) _n SO ₃ X (10) (wherein R is an alkyl group, preferably an alkyl group having 8 to 20 carbon atoms, X is hydrogen, a cation atom or a cation atom) Group, n is the number of moles of ethylene oxide added, usually 1 to
An integer of 10, preferably 2 to 4, is shown. ) Examples of the alkyl ether sulfate compound include tetraoxyethylene lauryl ether sulfate and salts thereof.

Alkyl phenyl ether sulfate ester compounds Examples of the alkyl phenyl ether sulfate ester compounds include compounds represented by the following formula (11), sulfated oil, sulfated fatty acid ester compounds, and sulfated olefin compounds. .

[0048]

Embedded image _{R-ph-O- (CH 2} CH 2 O) n SO 3 X ... Equation (11) (wherein, R is an alkyl group, preferably an alkyl group having 8 to 20 carbon atoms, X is hydrogen, Cation atom or cation atom group, n is the number of moles of ethylene oxide added, usually 1 to
An integer of 10, preferably 2 to 4, is shown. ph represents a phenylene group. ) A fluorine-based surfactant in which hydrogen of an alkyl group of the surfactants represented by the above items 1 to 3 is substituted with fluorine. -OSO ₃
The surfactant having a -group is excellent in particle removability, but becomes less effective as the alkalinity becomes stronger. It depends on the type, so it cannot be said unequivocally, but pH 10
In Nos. 12 to 12, the surfactant having a —SO ₃ — group exhibits higher particle removability.

Among the nonionic surfactants, as the polyethylene glycol type, polyoxyethylene alkylphenyl ether, polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene / polyoxypropylene. -Block polymers, polyoxyethylene-polyoxybutylene block polymers, etc. may be mentioned. Examples of the polyhydric alcohol type include glycerin fatty acid ester and sorbitan fatty acid ester. Out of these surfactants, it has excellent decontamination properties,
Moreover, in terms of excellent biodegradability, polyoxyethylene alkyl ether, polyoxyethylene
A polyoxypropylene block polymer, a polyoxyethylene polyoxybutylene block polymer, or the like is used.

The concentration of the surfactant in the alkaline detergent used in the present invention is usually 0.0001 to the detergent.
0.5% by weight, preferably 0.0003 to 0.1% by weight
Is. If the concentration of the surfactant is too low, the performance of removing the particle contamination by the surfactant is not sufficient. Conversely, if the concentration is too high, there is no change in the performance of removing the particle contamination.
In some cases, the foaming becomes remarkable, which makes it unsuitable for the cleaning process, and the load when biodegrading the waste liquid increases.

The surfactant added to the alkaline detergent used in the present invention may be added in any form of salt or acid. Examples of salts include alkali metal salts such as sodium and potassium, ammonium salts, primary, secondary, or tertiary amine salts. In cleaning the substrate surface in the semiconductor device or display device manufacturing process, considering that metal contamination adversely affects the transistor performance, the surfactant used does not contain a metal salt, an acid form, or an ammonium salt, The forms such as monoethanolamine salt and triethanolamine salt are preferable.

The alkaline detergent used in the present invention may further contain other components. Other components include organic sulfur-containing compounds (2-mercaptothiazoline, 2-mercaptoimidazoline, 2-mercaptoethanol, thioglycerol, etc.), organic nitrogen-containing compounds (benzotriazole, 3-aminotriazole, N
(R) ₃ (R is an alkyl group having 1 to 4 carbon atoms), N (RO
H) ₃ (R is an alkyl group having 1 to 4 carbon atoms), urea, thiourea, etc., water-soluble polymer (polyethylene glycol, polyvinyl alcohol, etc.), alkyl alcohol compound (ROH (R is alkyl having 1 to 4 carbon atoms) Group)) and the like, acid such as sulfuric acid and hydrochloric acid, reducing agent such as hydrazine, and dissolved gas such as hydrogen, argon and nitrogen.

(A-4) Solvent for alkaline detergent As the solvent for the alkaline detergent used in the present invention, water,
An organic solvent or a mixed solvent thereof may be used. Among them, water is preferable as the solvent from the viewpoint of waste liquid treatment cost. As water, deionized water, preferably ultrapure water, is usually used. Electrolytic ionized water obtained by electrolysis of water and hydrogen water obtained by dissolving hydrogen gas in water have excellent particle removal and adhesion prevention properties as compared with water, so they are mixed with other solvents. Alternatively, it is also preferable to use it alone as a solvent.

(A-5) pH of alkaline cleaning agent The pH of the alkaline cleaning agent used in the present invention depends on the alkaline components used and other additives such as complexing agents, but the pH of the alkaline cleaning agent is 9 or more. It is preferable from the viewpoint of removal and prevention of adhesion. The pH may be 9 or higher, but generally,
It is usually preferably pH 9 to 12, and particularly preferably pH 9.5 to 11.5. Further, a known pH adjusting agent may be used within a range that does not impair the effects of the present invention. Even if the pH is too high, a high effect corresponding to a high pH value cannot be expected, so that a large amount of alkali is required, which is economically disadvantageous, and the risk of damaging the substrate surface by etching increases.

(B) Cleaning with hydrofluoric acid in step (2) The substrate surface cleaning using the hydrofluoric acid-containing cleaning agent used in step (2) of the present invention uses a cleaning agent having a specific hydrofluoric acid content. This is a step of cleaning the substrate surface for a specific time or less. Specifically, the hydrofluoric acid content C (% by weight) is 0.03 to
Using a cleaning agent of 3% by weight, the cleaning time t (second) of the substrate with the cleaning agent is 45 seconds or less, and C and t are 0.
The cleaning step is characterized by having a relationship of 25 ≦ tC ^1.29 ≦ 5.

(B-1) tC ^1.29 in Step (2) In step (2) of the present invention, the relationship between the hydrofluoric acid content C (wt%) in the cleaning agent and the cleaning time t (second) is 0.25 ≦
It is characterized by being expressed by tC ^1.29 ≦ 5. Usually, in the hydrofluoric acid solution cleaning, if the hydrofluoric acid content in the hydrofluoric acid solution used is too high, or if the cleaning time is too long,
The increase in the etching amount causes problems such as a change in processing dimension and contamination (particle contamination, watermark) due to the hydrophobicity of the silicon surface. On the other hand, if the hydrofluoric acid content is too low or the cleaning time is too short, there is a concern that the metal stain removability may deteriorate.

The present inventors diligently studied a cleaning process using a hydrofluoric acid-containing cleaning agent, which is combined with the above-described cleaning process using an alkaline cleaning agent in the step (1). As a result, in addition to individually defining the specific hydrofluoric acid content C (% by weight) and the specific cleaning time t (seconds), both C and t have a specific relational expression, 0.25 ≦ tC ^1.29. In the case of ≦ 5, it has been found that both removal of sufficient metal contamination on the substrate surface and solution of problems such as processing dimension change can be achieved, and the present invention has been completed. The value represented by tC ^1.29 is 0.25 to 5, preferably 0.4 to 4, and more preferably 0.6 to 3. If this value is too small, the metal contamination cannot be removed sufficiently, and if it is too large, the etching amount increases more than necessary, and the contamination due to the process dimension change and the hydrophobicity of the silicon surface (particle contamination, watermark ) And other problems occur, which is not preferable.

(B-2) Hydrofluoric acid content Content of hydrofluoric acid in the hydrofluoric acid-containing detergent used in the present invention C
(Wt%) is usually 0.03 to 3 wt%, preferably 0.1 to 1 wt%, and particularly preferably 0.2 to 0.8 wt%. If the content of hydrofluoric acid is too low, the efficiency of removing metal contamination is low. On the contrary, if the concentration is too high, not only a high effect commensurate with the high concentration cannot be expected, but also the etching rate becomes too fast, which makes it difficult to control the etching amount to a certain value or less, which is not preferable.

(B-3) Cleaning Time in Step (2) The cleaning time in step (2) of the present invention, that is, the cleaning time t (second) of the substrate with the hydrofluoric acid-containing cleaning agent is 45 seconds or less. The cleaning time t (seconds) may be appropriately determined by the hydrofluoric acid content C (% by weight) in the cleaning agent as long as the above relational expressions relating to t and C are satisfied. The cleaning time t (second) is preferably 20 seconds or less, more preferably 10 seconds or less, although it depends on the hydrofluoric acid content C (wt%). Cleaning time t
The lower limit of (second) may be appropriately selected depending on the desired substrate cleanliness, but is usually 1 second or more. Although the lower limit of the cleaning time depends on the movable limit of the apparatus used for cleaning, for example, when using a single wafer cleaning apparatus, the lower limit of the cleaning time between the cleaning agent and the substrate should be about 1 second. Can be done. If the hydrofluoric acid content in the detergent is higher within the range of the hydrofluoric acid content C (% by weight) described above, it is possible to perform efficient cleaning in a shorter cleaning time, which is preferable. If the cleaning time in the step (2) of the present invention is too long, not only the decontamination effect commensurate with the time spent cannot be obtained, but also the number of substrates to be processed per unit time is reduced, and further, it is used in a single-wafer cleaning apparatus. In that case, a large amount of acid waste liquid needs to be treated, which is not preferable.

(B-4) Solvent for hydrofluoric acid-containing detergent As the solvent for the hydrofluoric acid-containing detergent used in the present invention, water,
An organic solvent or a mixed solvent thereof may be used. Among them, water is preferable as the solvent from the viewpoint of waste liquid treatment cost. As the water, deionized water, preferably ultrapure water is usually used, but electrolytic ionized water obtained by electrolysis of water and hydrogen water obtained by dissolving hydrogen gas in water are themselves compared to water. Since it has excellent particle removability and anti-adhesion property, it is also preferable to mix it with another solvent or use it alone as a solvent.

(B-5) Additives to Hydrofluoric Acid-Containing Detergent The hydrofluoric acid-containing detergent used in the present invention may further contain other components. Other components include surfactants such as those used in the alkaline cleaner in step (1); acids such as hydrochloric acid, sulfuric acid, nitric acid, acetic acid; alkaline components such as ammonia; buffering agents such as ammonium fluoride; peroxides. Oxidizing agents such as hydrogen, ozone, oxygen; reducing agents such as hydrazine; organic sulfur-containing compounds (2-mercaptothiazoline, 2-mercaptoimidazoline, thioglycerol, etc.), organic nitrogen-containing compounds (benzotriazole,
3-aminotriazole, urea, thiourea, etc.), water-soluble polymers (polyethylene glycol, polyvinyl alcohol, etc.), anticorrosive agents such as alkyl alcohol compounds, dissolved gases such as hydrogen, argon, nitrogen and the like.

The method for preparing the above-mentioned detergents (alkaline detergents and hydrofluoric acid-containing detergents) used in the present invention may be a conventionally known method. Detergent constituents (eg ammonium hydroxide, solvent, optionally complexing agent,
Of the other components such as a surfactant), any two components, or three or more components may be mixed in advance, and then the remaining components may be mixed, or all of them may be mixed at once.

(C) Combination of step (1) and step (2) In the cleaning method of the present invention including step (1) and step (2) described above, step (2) is performed after step (1) is performed. ) Is performed. By washing in this order,
A highly clean substrate surface can be obtained in a short time. It may be appropriately selected depending on the required cleanliness level of the substrate surface, the type of material on the substrate or the substrate surface, the type of additive to the cleaning agent, and the like. Since the alkaline cleaner of the step (1) contains the complexing agent, even if the alkaline cleaner unintentionally contains the metal impurity, the action of the complexing agent causes the metal impurity to be generated on the substrate surface. It is preferable because it can be prevented from adhering to, and not only particle contamination but also metal contamination can be extremely highly reduced.

By carrying out the step (2) after the step (1), it is possible to extremely reduce the contamination of organic substances on the substrate due to a surfactant or the like, which is preferable. When a surfactant is added to an alkaline cleaning agent, there is a concern that the surfactant may be adsorbed on the substrate surface and remain in a trace amount depending on the type of the surfactant and the substrate surface material. It can be removed by (2). Note that another substrate cleaning process may be performed between the process (1) and the process (2).

(D) Other cleaning conditions The cleaning in the present invention (cleaning with an alkaline cleaning agent or a cleaning agent containing hydrofluoric acid) may be carried out at the liquid temperature of the cleaning agent used, but the cleaning effect is improved. It may be heated for the purpose. The alkaline detergent in step (1) is usually used in the range of room temperature to 90 ° C. Also step (2)
The hydrofluoric acid-containing detergent is usually used at room temperature.
You may heat up to about ℃. If the cleaning agent temperature is too high, the etching amount of the silicon oxide film or the like increases, and side effects such as a change in processing dimension occur.

The cleaning may be carried out in combination with a cleaning method using physical force, for example, mechanical cleaning such as scrub cleaning using a cleaning brush, or ultrasonic cleaning. In particular, when performing ultrasonic cleaning or brush scrubbing when cleaning with the alkaline cleaning agent in the step (1) using a single-wafer cleaning device described later, the removal property of particle contamination is further improved and the cleaning time is shortened. It is also preferable because it leads to. Furthermore, washing with electrolyzed ionized water obtained by electrolysis of water or hydrogen water in which hydrogen gas is dissolved in water,
It may be combined before and / or after the cleaning method of the present invention.

(E) Cleaning Device, etc. The cleaning device using the present invention may be of any form as long as it is a cleaning device capable of carrying out the cleaning method of the present invention, that is, the method of bringing a cleaning agent into direct contact with the substrate. The method of contacting the cleaning agent with the substrate is a dip method in which the cleaning agent is filled in the cleaning tank to immerse the substrate, a spin method in which the substrate is rotated at a high speed while flowing the cleaning solution from the nozzle onto the substrate, and the solution is sprayed onto the substrate. Examples include a spray type for washing. As an apparatus for performing such cleaning, there are a batch type cleaning apparatus for simultaneously cleaning a plurality of substrates contained in a cassette, a single wafer cleaning apparatus for mounting one substrate on a holder and cleaning the same. is there. Although the cleaning method of the present invention can be applied to any of the above methods, it is preferably applied to a spin type or spray type cleaning device from the viewpoint of more efficient decontamination in a short time. Specifically, it is preferable to apply the cleaning method of the present invention to a single-wafer cleaning apparatus in which a reduction in cleaning time and a reduction in the amount of cleaning agent used are problems, because these problems are solved.

(F) Substrate to be Washed, etc. The washing method of the present invention is applied to semiconductors, glass, metals, ceramics, resins, etc., in which metal contamination or particle contamination poses a problem.
It is used for cleaning the surface of substrates such as magnetic materials and superconductors.
In particular, it is suitably used for cleaning semiconductor device substrates and display device substrates, which require high cleanliness of the substrate surface. As the material of these substrates and wirings and electrodes existing on the surface thereof, semiconductor materials such as Si, Ge (germanium), GaAs (gallium arsenide); S
iO ₂ , silicon nitride, hydrogen silsesquioxane (HS
Q), glass, aluminum oxide, transition metal oxides (titanium oxide, tantalum oxide, hafnium oxide, zirconium oxide, etc.), (Ba, Sr) TiO ₃ (BST), polyimide, insulating materials such as organic thermosetting resins; W (tungsten), Cu (copper), Cr (chrome), Co (cobalt), Mo (molybdenum), Ru (ruthenium), A
Examples include metals such as u (gold), Pt (platinum), Ag (silver), and Al (aluminum), alloys thereof, silicide, nitride, and the like.

In particular, in a semiconductor device substrate having a semiconductor material such as silicon, or an insulating material such as silicon nitride, silicon oxide, or glass on a part or the entire surface of the substrate, usually not only particle contamination but also metal contamination is extremely reduced. Therefore, the cleaning method of the present invention is preferably used.

[0070]

EXAMPLES Specific examples of the present invention will be described below with reference to examples. The present invention is not limited to the following examples unless it exceeds the gist. (Preparation of contaminated silicon wafer, etc.) 4 or 6 inch silicon wafer is treated with metal ions (Fe, Al, C
u, Zn) was immersed in the APM detergent. This A
PM cleaning agent is 29% by weight ammonia water, 31% by weight
Hydrogen peroxide solution and water were mixed at a volume ratio of 1: 1: 5, and the metal ion-containing aqueous solution was added to the mixture.
Metal ion-containing APM containing 20 ppb of e, 1 ppb of Al, 1 ppm of Cu, and 200 ppb of Zn
The cleaning agent was adjusted. The silicon wafer after the immersion was washed with ultrapure water for 10 minutes and dried with a nitrogen blower or a spin dryer to prepare a metal-contaminated silicon wafer. The metal (Fe, Al,
The Cu and Zn) analyzes were performed in the same manner for both the contaminated silicon wafer and the cleaned silicon wafer. The method is as follows: 0.1% by weight of hydrofluoric acid and 1
An aqueous solution containing hydrogen peroxide in a weight percentage was contacted and recovered. And an inductively coupled plasma mass spectrometer (ICP-M
The amount of metal recovered was measured using S) and converted into substrate surface concentration (atoms / cm ² ) to obtain the analysis result. Furthermore, the value obtained by summing all the concentrations of these metals is "total metal concentration (atoms /
cm ² ) ”. The analysis results of the contaminated silicon wafer are shown in Table 1-1 and Table 1-2.

Example 1 “Evaluation of Metal Contamination Cleaning Property by Two-Step Cleaning” A silicon wafer contaminated with metal was subjected to a step (1) and a step shown in Table 1-1 by using a single wafer cleaning apparatus. Metal contamination cleaning was performed by the two-step cleaning method of (2). The order of step (1) and step (2) is also described in the table. That is, when the step (2) is performed after the step (1),
2 ”. The same applies to all the tables below. In the step (1), the complexing agent shown in Table 1-1 was added to the APM1 cleaning agent (29% by weight aqueous ammonia, 31% by weight aqueous hydrogen peroxide and water mixed at a volume ratio of 1: 2: 80). A cleaning agent prepared was used. Incidentally, these steps (1)
The pH of the cleaning agent used in 1. was about 10. Rotation speed of silicon wafer in single-wafer cleaning equipment is 1000 rp
m, flow rate of cleaning agent is 1 liter / min, cleaning time is 30
Second, the liquid temperature was 80 ° C. In step (2), Table 1-1
The hydrofluoric acid aqueous solution having the hydrofluoric acid content shown in was used. Rotation speed of silicon wafer in single wafer cleaning system is 600 rp
m, the flow rate of the cleaning liquid was 1 liter / min, cleaning was performed for the cleaning time shown in Table 1-1, and the liquid temperature was room temperature. This 2
The results of step cleaning are shown in Table 1-1.

<Comparative Examples 1 and 2> The step (1) was not performed, and the HPM detergent (35% by weight) was used as the detergent in the step (2).
Hydrochloric acid, 31 wt% hydrogen peroxide solution, and water in a volume ratio of 1:
Aqueous solution mixed at 1:80) and a liquid temperature of 60
Washing was carried out in the same manner as in Example 1 except that the washing temperature was set to the temperature shown in Table 1-1. The results are shown in Table 1-1. <Comparative Example 53> The step (1) was repeated without performing the step (2).
Cleaning was performed in the same manner as in Example 1 except that the same APM1 cleaning agent as in Example 71 was used as the cleaning agent in Example 1 without using the complexing agent. The results are shown in Table 1-1. <Comparative Example 4> As the cleaning agent in the step (1), the same APM1 cleaning agent as in Example 1 was used without containing a complexing agent, and as the cleaning agent in the step (2), the same HPM cleaning solution as in Comparative Example 1 was used. Was used, and the cleaning was performed in the same manner as in Example 1 except that the liquid temperature was 60 ° C. and the cleaning time was as shown in Table 1-1. The results are shown in Table 1-1.

<Example 2> In the step (1), the cleaning time is 6
Example except that the solution temperature was set to 0 ° C., the solution temperature was set to 50 ° C., and the step (2) was performed at room temperature at the cleaning time with the hydrofluoric acid aqueous solution having the hydrofluoric acid content shown in Table 1-1 as the cleaning agent. Washing was performed in the same manner as in 1. The results are shown in Table 1-1.

[0074]

[Table 1]

<Examples 3 to 7, Comparative Examples 5 and 6> In the step (1), the APM2 cleaning agent (29% by weight ammonia water, 31% by weight hydrogen peroxide solution and water in a volume ratio of 1 :) was used as a cleaning agent.
Aqueous solution mixed at 2:40) or a solution obtained by adding a complexing agent or a surfactant shown in Table 1-2 to the solution at a liquid temperature of 8
The temperature was 0 ° C. The pH of the cleaning agent used in step (1) is about 1
It was 0.5. And, except for the above, the embodiment (1)
Was performed in the same manner as in the step (1). In the step (2),
As the cleaning agent, an aqueous hydrofluoric acid solution having the hydrofluoric acid content shown in Table 1-2 was used, and the cleaning time and the process sequence were the same as in Table 1-2.
Washing was performed in the same manner as in Example 1 except that the procedure was as shown in. The results are shown in Table 1-2.

[0076]

[Table 2]

As shown in Table 1-1 and Table 1-2,
In the present invention in which the step (1) of cleaning with the complexing agent-containing alkaline cleaning agent and the step (2) of cleaning with an aqueous solution of hydrofluoric acid are combined, the total metal concentration on the surface of the silicon wafer is obviously low and metal contamination is caused. It can be seen that the cleaning property of is excellent. Further, it can be seen that the cleaning method of the present invention is excellent in the metal contamination cleaning performance as compared with the conventionally used HPM cleaning, APM cleaning, or a cleaning method combining these (RCA cleaning).

<Examples 8 to 12, Comparative Example 7>"Evaluation of Particle Contamination Cleaning Property" In a 6-inch circle on a substrate, Si ₃ N ₄ particles (particles) having a particle diameter of 0.13 μm or more are 1000- 3000 silicon wafers adhered were cleaned by using a single-wafer cleaning device in two steps of step (1) and step (2) as shown in Table 2 to clean particles. In the step (1), cleaning was performed using an APM2 cleaning agent to which a complexing agent was added or a cleaning agent prepared by adding the surfactant shown in Table 2 thereto. The number of rotations of a silicon wafer in a single wafer cleaning apparatus is 1000
rpm, cleaning liquid volume 1 liter / min, cleaning time 6
The liquid temperature was set to room temperature for 0 seconds, and the substrate was cleaned while being irradiated with ultrasonic waves. The pH of the cleaning agent used in this step (1) was about 10.3. As the cleaning agent in the step (2), an aqueous hydrofluoric acid solution having the hydrofluoric acid content shown in Table 2 was used. The number of rotations of the silicon wafer in the single wafer cleaning apparatus was 1000 rpm, the cleaning liquid amount was 1 liter / min, the cleaning time was as shown in Table 2, and the liquid temperature was room temperature. The order of step (1) and step (2) is as shown in Table 2. Based on the removal rate obtained from the measurement of the number of particles remaining on the surface of the cleaned silicon wafer obtained after cleaning, the contamination particle removal rate was evaluated in the following five stages. That is, a removal rate of 80% or more is defined as removability AAA, and 60% or more and 80%
Less than AA, 40% or more and less than 60% A, 20% or more 4
B was defined as less than 0% and C as less than 20%. The results are shown in Table 2.

<Comparative Example 8> The same HPM cleaning agent as in Comparative Example 1 was used as the cleaning agent in the step (2), and the liquid temperature was set to 60.
Cleaning was performed in the same manner as in Example 8 except that the temperature and the cleaning time were changed to those shown in Table 2. The results are shown in Table 2.

[0080]

[Table 3]

As shown in Table 2, the cleaning method of the present invention is clearly superior in the particle contamination cleaning performance, as compared with the RCA cleaning method combining the APM cleaning and HPM cleaning which have been conventionally used. I understand.

<Example 13 and Comparative Example 9>"Evaluation of dimensional change in processing of silicon wafer after cleaning" Using a single wafer cleaning apparatus, a hydrofluoric acid shown in Table 3 was prepared for a 4-inch silicon wafer with an oxide film. Cleaning was performed using an aqueous solution of hydrofluoric acid having a content rate, and changes in the processing dimensions of the silicon wafer were evaluated. The rotation speed of the silicon wafer in the single wafer cleaning device is 600 rpm, the flow rate of the cleaning liquid is 1 liter / minute,
The liquid temperature was room temperature, and the cleaning time was as shown in Table 3.
Wafer surface etching amount (etched film thickness)
If the value exceeds 10 (Å), it is regarded as "defective" and 10 (Å)
The following cases were defined as “good”. (Observation of surface state of silicon wafer after cleaning) 1 ml of water was dropped on the surface of the silicon wafer after cleaning to observe the surface state. The results are shown in Table 3.

[0083]

[Table 4]

As shown in Table 3, the hydrofluoric acid content C and
An expression consisting of the cleaning time t with this hydrofluoric acid-containing cleaning liquid,
In the present invention in which C ^1.29 is 5 or less, the etching is obviously good, and since the surface of the silicon wafer retains hydrophilicity, the oxide film is not excessively etched and the processing dimensional change is small, which is preferable. Recognize. As is clear from the above results, the cleaning method of the present invention can remove both metal contamination and particle contamination on the substrate surface in an extremely short time as compared with the conventional cleaning method (comparative example). It has an excellent effect that there are almost no side effects such as changes in processing dimensions.

[0085]

According to the cleaning method of the present invention, when cleaning a semiconductor substrate such as a silicon wafer to be cleaned, problems such as a change in processing dimension with respect to the substrate are suppressed to an extremely low level, and the surface of the substrate can be processed in an extremely short time. Both metal contamination and particle contamination can be effectively removed. Therefore, it is industrially very useful when used as a surface treatment method for cleaning contaminants in the manufacturing process of semiconductor devices and display devices.

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2H088 FA30 HA01 KA30 MA20                 2H090 JA00 JB00 JB02 JC19 JD01                       JD08                 3B201 AA02 AA03 BA02 BB82 BB92                       BB93 BB96 CC01 CC12 CC13

Claims (8)

[Claims] 1. A substrate surface cleaning method comprising at least the following steps (1) and (2), wherein step (2) is performed after step (1) is performed. Step (1) A cleaning step of cleaning the substrate surface with a complexing agent-containing alkaline cleaning agent. Step (2) A cleaning agent having a hydrofluoric acid content C (% by weight) of 0.03 to 3% by weight is used, a cleaning time t (seconds) of the substrate with the cleaning agent is 45 seconds or less, and C t is 0.25
≤ tC ^1.29 ≤ 5 cleaning process. 2. The substrate surface cleaning method according to claim 1, wherein the complexing agent is a compound having nitrogen as a donor atom and a carboxyl group and / or a phosphonic acid group. 3. The complexing agent is a compound having an aromatic hydrocarbon ring and having two or more OH groups and / or O ⁻ groups directly bonded to the carbon atoms constituting the ring. The substrate surface cleaning method according to claim 1 or 2. 4. The complexing agent is ethylenediaminetetraacetic acid [ED
One or more selected from the group consisting of TA], ethylenediaminedioltohydroxyphenylacetic acid [EDDHA] and / or its derivative, diethylenetriaminepentaacetic acid [DTPA], propylenediaminetetra (methylenephosphonic acid) [PDTMP] The substrate surface cleaning method according to any one of claims 1 to 3, wherein: 5. The substrate surface cleaning method according to claim 1, wherein the concentration of the complexing agent in the cleaning agent used in step (1) is 1 to 10000 ppm by weight. 6. The substrate surface cleaning method according to claim 1, wherein the cleaning agent used in step (1) contains ammonium hydroxide. 7. The substrate surface cleaning method according to claim 1, wherein the cleaning agent used in the step (1) has a pH of 9 or more. 8. A substrate surface cleaning apparatus using the substrate surface cleaning method according to any one of claims 1 to 7.