JPH0940997A - Surface treatment composition and surface treatment of substrate using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a surface treatment compsn. excellent in metal (particularly aluminum) attachment inhibition effect. SOLUTION: A liq. surface treatment compsn. contains at least one kind of complexing agent as a metal attachment inhibitor selected from among quinolinol and its derivs., ethylenediamine di-o-hydroxyphenylacetate, 2- hydroxy-1-(2-hydroxy-5-methylphenylazo)-4-nathphalenesulfonic acid, diammonium 4,4'-bis(3,4-dihydroxyphenylazo)-2,2'-stilbenedisulfonate, Pyrocatechol Violet, o,o'-dihydroxyazobenzene, 1',2-dihydroxy-5-nitro-1,2'-azonaphthalene-4-sulfonic acid, and N,N'-bis(2-hydroxybenzyl)ethylenediamine N,N'-diacetate.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a surface treatment composition and a method for treating a surface of a substrate using the same. More specifically, the present invention relates to a surface treatment method for a substrate capable of preventing contamination of the surface treatment composition with a metal impurity and stably achieving an extremely clean substrate surface, and a surface treatment composition used therefor.

[0002]

2. Description of the Related Art With the increasing integration of various devices typified by VLSIs and TFT liquid crystals, the demand for cleaning the substrate surface is becoming increasingly severe. There are various pollutants that hinder cleaning, and among these pollutants, metal contamination particularly deteriorates the electrical characteristics of the device. In order to prevent such deterioration, it is necessary to reduce the concentration of metal impurities on the surface of the substrate on which the device is formed as much as possible. Therefore, the surface of the substrate is generally cleaned with a specific type of cleaning agent.

Conventionally, cleaning agents of this type include ultrapure water,
An aqueous solution of an acid, an alkali, an oxidizing agent, a surfactant or the like, electrolytic ion water, a high-purity organic solvent, etc. are generally used.
In addition to excellent cleaning performance, the cleaning agent is required to have an extremely low impurity concentration in the cleaning agent in order to prevent metal contamination from the cleaning agent to the substrate. In order to satisfy such requirements, the purification of chemicals for semiconductors is promoted, and the concentration of metal impurities contained in the chemicals immediately after purification is
It has reached a level at which detection is difficult with current analytical techniques.

[0004] As described above, despite the fact that the impurities in the cleaning agent have reached a level that is difficult to detect, it is still difficult to achieve a high-purity surface due to the metal impurities removed from the substrate in the cleaning tank. However, it is inevitable to contaminate the cleaning agent. That is, the metal impurities once detached from the surface are mixed into the cleaning agent and contaminate the cleaning agent. Then, metal impurities are attached to the substrate from the contaminated cleaning agent (reverse contamination).

In the semiconductor cleaning process, [ammonia + hydrogen peroxide + water] cleaning (commonly called “SC-1 cleaning”) (RC
A Review, p.187-206, June (1970)) is widely used. The main cleaning is usually performed at 40 to 90 ° C., and the cleaning composition is usually (30 wt% ammonia water):
(31 wt% hydrogen peroxide water): (water) = 0.05 to 1:
The one having a capacity ratio of about 1: 5 is used. But,
This cleaning method has high particle removing ability and organic substance removing ability, but has a problem that when a very small amount of metal such as Fe, Al, Zn, and Ni is present in the solution, it adheres to the substrate surface and causes reverse contamination. . Therefore, in the semiconductor cleaning process, normally, [ammonia + hydrogen peroxide + water] cleaning is followed by [hydrochloric acid + hydrogen peroxide + water] cleaning (commonly referred to as “SC-2
Cleaning with an acidic cleaning agent such as “cleaning”) is performed to remove metal contamination on the substrate surface.

As described above, there has been a demand for a technique for preventing such reverse contamination in order to efficiently and stably obtain a highly clean surface in the cleaning process. The problem that metal impurities in the solution adhere to the surface of the substrate and cause reverse contamination is not only the cleaning process but also the substrate using the solution such as alkali etching of the silicon substrate or etching process of the silicon oxide film with dilute hydrofluoric acid. It is a big problem in the overall surface treatment process. In the diluted hydrofluoric acid etching step, if there is a noble metal impurity such as Cu or Au in the liquid, it adheres to the silicon surface and significantly degrades the electrical characteristics of the device such as carrier lifetime. In addition, in the alkali etching step, if there are trace metal impurities such as Fe and Al in the solution, they easily adhere to the substrate surface. Therefore, there has been a strong demand for a technique for preventing such pollution.

In order to solve this problem, a complexing agent such as a chelating agent is added to the surface treatment agent to capture metal impurities in the solution as a stable water-soluble complex and prevent adhesion to the substrate surface. Is proposed. JP-A-50-158281
In the publication, it is proposed to add a complexing agent such as ammonium cyanide or ethylenediaminetetraacetic acid (EDTA) to an aqueous solution of tetraalkylammonium hydroxide to prevent metal impurities from adhering to the surface of the semiconductor substrate. In JP-A-3-219000, a chelating agent such as catechol and tyrone is used, and in JP-A-5-275405, a phosphonic acid-based chelating agent or a complexing agent such as condensed phosphoric acid is used.
In Japanese Patent Laid-Open No. 6-163495, a complexing agent such as a hydrazone derivative is added to an alkaline cleaning solution such as [ammonia + hydrogen peroxide + water] to prevent metal impurities from adhering to the substrate. With pollution,
Techniques have been proposed to achieve a substrate surface free of metal contamination.

However, when these complexing agents are added, the effect of preventing or removing specific metals (for example, Fe) is observed, but metals other than Fe (which are likely to contaminate the processing liquid or the substrate) For example, with respect to Al), the effect of the complexing agent is extremely small, and there is a problem that a sufficient effect cannot be obtained even if a large amount of complexing agent is added.

In order to solve this problem, JP-A-6-216098 discloses that a substrate is washed with a [ammonia + hydrogen peroxide + water] washing solution containing a chelating agent such as a phosphonic acid chelating agent, and then the like. It is described to rinse with a hydrofluoric acid solution of 1 ppm or more. This is because Al contamination on the substrate surface cannot be sufficiently reduced even if a phosphonic acid-based chelating agent is added, so that Al is to be removed by etching using a hydrofluoric acid aqueous solution of 1 ppm or more in a subsequent step. . As described above, the conventional metal adhesion preventing method is not sufficiently effective, and when the substrate needs to be cleaned,
Inevitably, metal contamination must be removed in the subsequent process, which increases the number of processes and causes an increase in production cost.

[0010]

As described above, the contamination of metal impurities from the surface treatment composition to the surface of the substrate has become a serious problem, but the technique for preventing it is still insufficient. Therefore, the addition of various complexing agents has been tried to prevent the adhesion, but the present situation is that the improvement has not yet been made.

The present invention has been made to solve the above problems, and it is possible to prevent the surface treatment composition from being contaminated with metal impurities and to achieve a stable and extremely clean substrate surface. It is an object of the present invention to provide a surface treatment method for a substrate and a surface treatment composition used therefor.

[0012]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, it has been found that a specific complexing agent is added and contained as a metal adhesion inhibitor in a surface treatment composition. The present inventors have found that the effect of preventing metal impurities from adhering to the substrate from the processing solution is remarkably improved, and arrived at the present invention.

That is, the gist of the present invention is as a metal adhesion inhibitor, quinolinol and its derivatives, ethylenediamine diorthohydroxyphenylacetic acid [common name: EDDH
A], 2-hydroxy-1- (2-hydroxy-5-methylphenylazo) -4-naphthalenesulfonic acid [common name: calmagite], 4,4′-bis (3,4-dihydroxyphenylazo) -2, Diammonium 2'-stilbene disulfonate [common name: stilbazo], pyrocatechol violet [common name: PV], o, o'-dihydroxyazobenzene, 1'2-dihydroxy-5-nitro-1,2'-azonaphthalene-4 -Sulfonic acid [common name:
Liquid surface treatment composition containing at least one complexing agent selected from Eriochrome Black T], N, N-bis (2-hydroxybenzyl) ethylenediamine-N, N-diacetic acid [common name: HBED], and It exists in a method for surface treatment of a substrate using the same.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
In the present invention, the surface treatment composition is a general term for surface treatment liquids used for the purpose of cleaning, etching, polishing, film formation of a substrate. In the present invention, the complexing agent used as the metal adhesion preventing agent is at least one selected from the above complexing agent group. The complexing agent is comprehensively judged and selected from the cleanliness level required for the substrate surface, the cost of the complexing agent, the chemical stability in the surface treatment composition to be added, etc. The agent is not the best.

From the standpoint of the effect of preventing metal adhesion when the content is constant, ethylenediaminedioltohydroxyphenylacetic acid or 2-hydroxy-1- (2-hydroxy-5-methylphenylazo) -4-naphthalenesulfonic acid is particularly preferable. It is excellent and is preferably used. Also, in terms of chemical stability, N, N-bis (2-hydroxybenzyl)
Ethylenediamine-N, N-diacetic acid is superior to quinolinol and its derivatives in terms of production cost of the complexing agent, and is preferably used when these are important.

Examples of the quinolinol and its derivative of the present invention include 8-quinolinol, 2-methyl-8-quinolinol, quinolinediol and the like, which are preferably used, but the present invention is not limited thereto. The amount of the complexing agent added as the metal anti-adhesive agent cannot be unconditionally determined because it depends on the type and amount of the metal impurities in the liquid that is the object of anti-adhesion and the cleanliness level required for the substrate surface. as the total amount of surface treatment composition, usually 10 ^-7 to 5 wt%, preferably 10 ^@ 6 to 0.1 wt%
It is. If the amount added is too small, the effect of preventing metal adhesion is not sufficient. On the other hand, if the amount is too large, no further effect can be obtained, and there is a risk that the complexing agent, which is a metal adhesion inhibitor, adheres to the substrate surface. Is high, which is not preferable.

As the main component, an aqueous solution of water, an acid, an alkali, an oxidizing agent, a reducing agent, a surfactant or the like, electrolytic ionic water, an organic solvent, or a mixed solution thereof is usually used. In particular, in an alkaline aqueous solution or a dilute hydrofluoric acid solution used for cleaning or etching a semiconductor substrate, the present invention is preferably used because metal impurities in the solution are extremely likely to adhere to the surface of the substrate.

In the present invention, the alkaline aqueous solution is a general term for aqueous solutions having a pH of more than 7. A typical example of the alkaline component is ammonia. In addition, alkali metal or alkaline earth metal hydroxides such as sodium hydroxide, potassium hydroxide and calcium hydroxide, alkaline salts such as sodium hydrogencarbonate and ammonium hydrogencarbonate, tetramethylammonium hydroxide and trimethyl-2-. A quaternary ammonium hydroxide such as hydroxyethylammonium hydroxide (choline) may also be used. It is safe to add two or more of these alkalis.
It is used so that the total concentration in the total solution of the surface treatment composition is 0.01 to 30% by weight.

Further, an oxidizing agent such as hydrogen peroxide may be appropriately mixed in such an alkaline aqueous solution.
In the semiconductor wafer cleaning process, when bare silicon (without an oxide film) is cleaned, an oxidizer is added to prevent etching and surface roughness of the wafer. When hydrogen peroxide is added to the alkaline aqueous solution of the present invention, it is usually used so that the concentration of hydrogen peroxide in the total solution of the surface treatment composition is in the range of 0.01 to 30% by weight.

The present invention is also preferably used for a surface treatment composition containing so-called alkaline electrolyzed water as a main component, which is said to be obtained by electrolyzing water. In the present invention, the method of adding the complexing agent to the surface treatment composition is not particularly limited. Of the components mainly constituting the surface treatment composition (for example, ammonia water, hydrogen peroxide water, water in the case of the cleaning composition used for the SC-1 cleaning), any one component or a plurality of components The complexing agent may be mixed in advance and the remaining components may be mixed and used afterwards, or the complexing agent may be mainly mixed and then used.

The surface treatment composition of the present invention is used for cleaning, etching, polishing, film-forming, etc. of substrates such as semiconductors, metals, glass, ceramics, plastics, magnetic materials and superconductors in which contamination of metallic impurities on the substrate is a problem. It is used for the surface treatment of. In particular, the present invention is preferably used for cleaning and etching a semiconductor substrate which requires a highly clean substrate surface. Among the cleaning of semiconductor substrates, in particular, [ammonia + hydrogen peroxide +
[Water] When the present invention is applied to alkaline cleaning such as cleaning, the problem of metal impurity adhesion to a substrate, which was a problem of the cleaning method, is improved.
It is extremely suitable because a highly clean substrate surface free from metal contamination is achieved together with organic contamination.

When the present invention is used for cleaning the substrate, a method of directly contacting the liquid with the substrate is used. Examples of such a cleaning method include dip-type cleaning in which a cleaning tank is filled with a cleaning solution to immerse the substrate, spray-type cleaning in which the solution is sprayed onto the substrate for cleaning, and spin-type cleaning in which the cleaning solution is dropped onto the substrate and rotated at a high speed. Etc. The present invention can be used in any of the above cleaning methods, but preferably dip cleaning is used.
The washing time is a suitable washing time, preferably 10 seconds to 30 minutes, more preferably 30 seconds to 15 minutes. If the time is too short, the cleaning effect will not be sufficient, and if it is too long, the throughput will only be deteriorated, and the cleaning effect will not increase and is meaningless. The washing may be performed at room temperature, but may be performed with heating for the purpose of improving the washing effect. Also,
At the time of washing, a washing method using physical force may be used in combination. Examples of such a cleaning method using physical force include ultrasonic cleaning and mechanical cleaning using a cleaning brush.

[0023]

EXAMPLES Next, specific embodiments of the present invention will be described with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof. Examples-1 to 10 and Comparative Examples-1 to 3 Ammonia water (30% by weight), hydrogen peroxide solution (31% by weight), and water were mixed at a volume ratio of 0.25: 1: 5 to obtain. A predetermined amount of the complexing agent shown in Table 1 as a metal adhesion preventing agent was added to the aqueous solvent to prepare a surface treatment composition. The added amount of the complexing agent is shown by weight% with respect to the aqueous solvent, and the name is shown by the above-mentioned common name. In addition, as a comparative example, a compound obtained by adding ethylenediaminetetrakis (methylphosphonic acid) [common name: EDTPO], which is a complexing agent described in JP-A-5-275405, to JP-A-6-163495. Also prepared were those to which oxalic bis (salicylidene hydrazide), which is the complexing agent described in 1., and those to which no complexing agent was added, were prepared.

The surface treatment solution thus prepared was treated with Al, F
Clean silicon wafers (p-type, CZ, plane orientation (100)) after adding e by 10 ppb each as chloride
For 10 minutes. During the immersion, the temperature of the surface treatment liquid is
Warmed and maintained at 40-50 ° C. The silicon wafer after the immersion was overflow-rinsed with ultrapure water for 10 minutes, then dried by nitrogen blowing, and A
l and Fe were quantified. A adhered on silicon wafer
l and Fe were recovered in a mixed solution of 0.1% by weight of hydrofluoric acid and 1% by weight of hydrogen peroxide, and the amount of the metal was measured by a flameless atomic absorption method, and converted into a substrate surface concentration (atoms / cm ² ). .
The results are shown in Table 1.

[0025]

[Table 1]

[0026]

The surface treatment composition of the present invention contains a specific complexing agent as a metal adhesion inhibitor, thereby preventing contamination of metal impurities such as Al and Fe from the surface treatment composition onto the substrate surface. An extremely clean substrate surface can be stably achieved. In particular, when the present invention is applied to alkali cleaning of a semiconductor substrate typified by [ammonia + hydrogen peroxide + water] cleaning and the like, the problem of metal impurity attachment to the substrate, which was a problem of the cleaning method, is improved. Thereby, by the washing,
A highly clean substrate surface free of metal contamination as well as particles and organic contamination is achieved. For this reason, acid cleaning such as [hydrochloric acid + hydrogen peroxide + water] cleaning, which has been conventionally used after the cleaning, can be omitted, and the cleaning cost and the cost of a clean room such as exhaust equipment can be significantly reduced. To become
This is a great advantage for industrial production of semiconductor integrated circuits. Further, when etching or cleaning a metal substrate or a substrate whose surface is formed of a metal film, if a metal having a lower ionization tendency than the metal to be treated is present as an impurity in the liquid, it is electrochemically attached to the substrate surface. However, when the present invention is used, the metal impurity becomes a stable water-soluble metal complex, which can be prevented. Further, when the present invention is applied to an abrasive slurry for polishing a substrate, it is possible to prevent metal impurities that are present in a large amount in the abrasive slurry and are concentrated in the slurry as the substrate is polished from adhering to the substrate. it can.

Claims (5)

[Claims] 1. A quinolinol and its derivative, ethylenediamine diorthohydroxyphenylacetic acid, 2-hydroxy-1- (2-hydroxy-) as a metal adhesion preventing agent.
5-Methylphenylazo) -4-naphthalenesulfonic acid, 4,4'-bis (3,4-dihydroxyphenylazo) -2,2'-stilbenedisulfonic acid diammonium, pyrocatechol violet, o, o'-dihydroxy Azobenzene, 1'2-dihydroxy-5-nitro-1,2'-azonaphthalene-4-sulfonic acid, N,
A liquid surface treatment composition comprising at least one complexing agent selected from N'-bis (2-hydroxybenzyl) ethylenediamine-N, N'-diacetic acid. 2. The surface treatment composition according to claim 1, which comprises an alkaline aqueous solution as a main component. 3. The surface treatment composition according to claim 2, wherein the alkaline aqueous solution is an aqueous solution containing ammonia and hydrogen peroxide. 4. A method for treating the surface of a substrate with the surface treatment composition according to claim 1. 5. The method according to claim 4, wherein the substrate is a semiconductor substrate.