KR20000063056A - Corrosion inhibitor for metals, cleaning liquid composition comprising the same and cleaning method using the same - Google Patents

Abstract

The present invention relates to corrosion inhibitors for metals containing imidazole, thiazole or triazoles having amino or thiol groups in the molecule. Such corrosion inhibitors are effective in preventing corrosion of metals, in particular copper and copper alloys, for example, in preventing corrosion of copper wiring in semiconductor devices.

Description

Corrosion inhibitor of metal, cleaning liquid composition containing the same and cleaning method using same {CORROSION INHIBITOR FOR METALS, CLEANING LIQUID COMPOSITION COMPRISING THE SAME AND CLEANING METHOD USING THE SAME}

The present invention relates to a metal corrosion inhibitor, a cleaning liquid composition containing the same, and a cleaning method using the same. In particular, the present invention relates to a cleaning liquid composition which is not corrosive to copper or a copper alloy and is suitable for cleaning semiconductor devices and the like having copper wiring, and a method for cleaning semiconductor devices and the like having copper wiring with the cleaning liquid composition.

Recently, various materials for high integration and high performance of semiconductor devices have been developed. In particular, as the wiring material in the device, a wiring material having a low resistance has been sought to increase the transmission speed of an electrical signal through the wiring.

To date, aluminum and its alloys have been used as wiring materials because of their easy processability. However, aluminum and its alloys are not sufficient in view of the performance of the device required for the improvement of performance and processing speed. Therefore, copper and its alloys are attracting attention as wiring materials with low resistance.

Generally, wiring is formed on a semiconductor element by forming a film of metal constituting the wiring on a silicon wafer, and then performing a lithography step and a dry-etching step to fill the space between the wirings with an insulating film. However, copper wiring is not widely used because it is difficult to process by a dry-etching process.

Recently, chemical mechanical polishing (CMP) using special abrasive materials and polishing pads has been developed, and the damascene method using CMP is drawing attention.

In this method, an insulating film is first formed on a wafer, and then a wiring groove is formed by a lithography step and a dry-etch step, and then a copper film is formed to fill the groove with copper, and the wafer is not a copper wafer. The copper film on top is removed by CMP. However, wiring to copper by CMP leaves a significant amount of abrasive or polishing debris formed by polishing after polishing of copper, or metal impurities contained in the abrasive or polishing pad, and these are the wafer surface and the back surface of the wafer surface. Is attached to. Therefore, it is necessary to clean or clean the polished wafer surface.

Generally, in order to remove particles on the wafer surface, it is important to fill the wafer surface and the particles with zeta potential having the same sign so as to have electrical repulsion and to prevent re-deposition of the free particles to the wafer surface. If the wash is basic, almost all materials have a negative zeta (ζ) -potential. Therefore, a basic washing liquid is preferably used. In addition, in order to remove metal impurities, a strongly acidic solution having high metal-dissolving power is preferably used.

However, it is known that copper and its alloys readily corrode with basic or acidic solutions. If the wafer surface where the copper wiring is exposed is washed with this basic or acidic solution, the copper surface is corroded after the cleaning. Therefore, the wiring resistance may increase or the wiring may be broken.

Many materials are known as corrosion inhibitors that do not corrode copper or its alloys. However, when they are used for cleaning semiconductor devices, there are many restrictions on such corrosion inhibitors. That is, since the wiring structure of the semiconductor element is very fine, pitting may occur, or the surface state may be rough, which may adversely affect the performance of the element even when the overall corrosion is prevented. Therefore, it is necessary to select a corrosion inhibitor that does not cause this problem.

Cleaning solutions for semiconductor devices sometimes have very low acid or base concentrations. In this case, the concentration of the corrosion inhibitor is also very low, and the effect of the corrosion inhibitor is unpredictable from the effect obtained with the usual concentration of corrosion inhibitor.

One object of the present invention is to provide a corrosion inhibitor which does not corrode metals, in particular copper or alloys thereof.

It is still another object of the present invention to provide a cleaning liquid composition and cleaning method suitable for cleaning a semiconductor device having copper wiring.

As a result of extensive research, it has been found that when a particular imidazole, thiazole or triazole compound is added to a cleaning liquid for cleaning of metals such as copper or its alloys, especially copper wiring of semiconductor devices, an excellent corrosion protection effect can be achieved. The present invention was completed.

Accordingly, the present invention provides a corrosion inhibitor containing at least one compound selected from the group consisting of imidazole, thiazole and triazole, having at least one group selected from the group consisting of amino and thiol groups in the molecule.

Preferred examples of imidazoles having at least one amino or thiol group in the molecule are 2-mercaptoimidazoline, 2-mercapto-1-methylimidazole and the like. Preferred examples of thiazoles having one or more amino or thiol groups in the molecule are 2-mercaptothiazoline, 2-aminothiazole and the like. Preferred examples of triazoles having one or more amino or thiol groups in the molecule are 3-aminotriazole, 4-aminotriazole, 2,5-diaminotriazole, 4-mercaptotriazole, 3-amino-5- Mercaptotriazole and the like.

The compounds may be used alone or in mixture of two or more.

Moreover, this invention relates to the cleaning liquid composition containing the said corrosion inhibitor of this invention.

In the present application, a cleaning liquid containing no corrosion inhibitor is referred to as a "cleaning liquid", while a cleaning liquid containing corrosion inhibitor is referred to as a "cleaning liquid composition".

The corrosion inhibitor of the present invention can be added to a conventional metal cleaning liquid to provide a cleaning liquid composition that does not corrode metal. When the cleaning liquid composition of the present invention is used for washing copper or its alloys, and particularly for washing semiconductor elements having copper wiring, the characteristics of the present invention are sufficiently exhibited.

The wash may be basic or acidic.

The concentration of the corrosion inhibitor of the present invention in the cleaning liquid composition is preferably 0.0001 to 10% by weight, more preferably 0.001 to 1% by weight.

If the concentration of the corrosion inhibitor of the present invention is too low, a sufficient corrosion protection effect cannot be achieved. If the concentration exceeds the upper limit, the corrosion protection effect no longer increases proportionally, and when the high concentration cleaning liquid composition is used for cleaning the semiconductor device, the amount of corrosion inhibitor absorbed on the surface of the semiconductor is increased. This makes it difficult to control the cleaning step of the semiconductor device.

The cleaning liquid composition of the present invention can be prepared by adding the corrosion inhibitor of the present invention to the cleaning liquid, stirring the mixture to dissolve the corrosion inhibitor in the cleaning liquid.

Any basic solution conventionally used to prepare the cleaning liquid can be used as the basic solution according to the present invention. Specific examples of basic solutions include aqueous solutions of inorganic bases (such as sodium hydroxide, potassium hydroxide, ammonium hydroxide, etc.), and aqueous solutions of organic bases (such as tetramethylammonium hydroxide, choline, etc.). Among them, purified aqueous solutions of ammonium hydroxide, tetramethylammonium hydroxide and choline are preferably used to remove fine particles or metal impurities from semiconductor devices. In particular, aqueous ammonium hydroxide solution is preferable.

Any acid solution conventionally used to prepare the cleaning liquid can be used as the acid solution according to the present invention. Specific examples of acidic solutions are acidic solutions of inorganic acids (such as hydrochloric acid, hydrofluoric acid, sulfuric acid, nitric acid, etc.), and acidic solutions of organic acids (such as oxalic acid, citric acid, malonic acid, malic acid, fumaric acid, maleic acid, and the like). Among them, purified acidic aqueous solutions such as, for example, hydrochloric acid, hydrofluoric acid, sulfuric acid, nitric acid, oxalic acid, citric acid and the like are preferable for removing fine particles or metal impurities from semiconductor devices.

Although the basic or acidic solutions can be used as they are, they can be used in the form of a mixture with other reagents that do not impair the properties of the corrosion inhibitor of the invention. In particular, basic or acidic solutions can be mixed with purified hydrogen peroxide or ammonium fluoride for cleaning of semiconductor devices.

Moreover, this invention relates to the method of cleaning a semiconductor element using the cleaning liquid composition of the said invention.

Corrosion inhibitors of the present invention may be added to any conventional metal cleaning liquid. The corrosion inhibitor of the present invention has an excellent effect when used in a cleaning liquid for cleaning copper or its alloys.

The corrosion inhibitor of the present invention is advantageously added to a cleaning liquid for cleaning a metal wiring, in particular a semiconductor device having copper wiring. Since the wiring pattern on the wafer constituting the semiconductor element is very fine, a corrosion inhibitor is required to prevent the overall corrosion amount and to not cause roughening of the fitting or the surface. When the wafer is washed with the cleaning liquid composition of the present invention, the adhered metal impurities or the message particles are removed, but no fitting or surface roughening occurs.

The cleaning of the wafer using the cleaning liquid composition of the present invention comprises immersion-cleaning, a combination of application of ultrasonic waves and immersion-cleaning, including immersing the wafer directly in the cleaning liquid composition, and brushing the wafer while spraying the cleaning liquid composition on the wafer surface. It can be performed by a combination of the brush-cleaning, brush-cleaning method and the application of ultrasonic waves, including. The cleaning liquid composition may be heated in the cleaning process.

The invention is illustrated by the following examples which do not limit the scope of the invention.

Examples 1 to 3 and Comparative Examples 1 to 3

To the 0.1% by weight of ammonia water as the cleaning solution, 0.01% by weight of the corrosion inhibitor shown in Table 1 is added to obtain a cleaning solution composition according to the present invention.

For comparison, the cleaning liquid containing no corrosion inhibitor of the present invention or a cleaning liquid containing other corrosion inhibitor other than the present invention is used.

The silicon wafer on which a 10,000-mm-thick copper film was formed by sputtering is immersed in the cleaning liquid composition or the cleaning liquid for 30 minutes. The thickness of the copper film is measured before and after immersion, and the corrosion rate is evaluated by calculating the dissolution rate of the copper film from the change in the thickness of the copper film.

The copper film thickness is measured by measuring the sheet resistance of the film with a sheet-resistometer (manufactured by NAPSON) and converting the measured resistance into the film thickness.

The surface state of the copper film is evaluated by observing the surface of the copper film before and after dipping with an electron microscope.

The results are shown in Table 1.

Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Anti-corrosion-type-concentration (% by weight) * 1) 0.01 * 2) 0.01 * 3) 0.01 * 4) 0.01 * 5) 0.01 --0 Result- Dissolution rate (Å / min)-Surface condition ^{* 6)} 2O 2O 2O 9X 10X 13X * 1) 2-mercaptothiazoline: C ₃ H ₅ NS ₂ * 2) 3-aminotriazole: C ₂ H ₄ N ₄ * 3) 2-mercaptoimidazoline: C ₃ H ₆ N ₂ S * 4) Methylpentinol: CH ₃ CH ₂ CH (CH ₃ ) (OH) C≡CH * 5) β, β'-thiodipropionic acid: S (CH ₂ CH ₂ COOH) ₂ * 6) Surface condition: O: No change, X: surface roughening occurs

As can be seen from the results in Table 1, the corrosion inhibitor of the present invention can effectively prevent corrosion of the basic solution and copper.

Examples 4 and 5, and Comparative Examples 4 and 5

To the 0.1 wt% aqueous hydrofluoric acid solution or 1 wt% hydrochloric acid solution as a washing liquid, 0.01 wt% of the corrosion inhibitor shown in Table 2 is added to obtain a cleaning liquid composition according to the present invention.

For comparison, the hydrochloric acid solution which does not contain the corrosion inhibitor of the present invention is used.

The silicon wafer on which a 10,000-mm-thick copper film was formed by sputtering is immersed in the cleaning liquid composition or the cleaning liquid for 30 minutes. The thickness of the copper film is measured before and after immersion in the same manner as in Examples 1 to 3, and the dissolution rate of the copper film is calculated from the change in the thickness of the copper film to evaluate the corrosion protection effect.

The thickness of the copper film is observed with an electron microscope before and after dipping to evaluate the surface state of the copper film.

The results are shown in Table 2.

Example 4 Comparative Example 4 Example 5 Comparative Example 5 Anticorrosion Agents- Type- Concentration (% by weight) * 7) * 1) 0.01 * 7)-0 * 8) * 1) 0.01 * 8)-0 Result- Dissolution rate (Å / min)-Surface condition ^{* 6)} 2O 15X 1O 16X * 1) and * 6): See * 1) and * 6) in Table 1 * 7) 0.1 wt% aqueous hydrofluoric acid solution * 8) 1 wt% hydrochloric acid aqueous solution

As can be seen from the results in Table 2, the corrosion inhibitor of the present invention can effectively prevent corrosion of the acid solution and copper.

While the above embodiment described the cleaning of the copper wiring of the semiconductor device, substantially the same results are obtained for copper and its alloys.

The cleaning liquid composition of the present invention has a corrosion protection effect on metals other than copper when the cleaning liquid is appropriately selected.

As can be seen from the above, the corrosion inhibitor of the present invention contains at least one compound selected from the group consisting of imidazole, thiazole and triazoles having at least one group selected from the group consisting of amino and thiol groups in the molecule, in particular metals, in particular To prevent corrosion of copper or its alloys.

According to the present invention, the corrosion inhibitor is added to a cleaning solution suitable for each metal to be cleaned, and the cleaning solution composition of the present invention can remove impurities from the metal surface and prevent corrosion of the metal.

According to the invention, the metal, especially the copper wiring of the semiconductor element, is cleaned with the cleaning liquid composition of the invention. Therefore, impurities are removed from the surface of the semiconductor element, surface roughening of the copper wiring does not occur, and no fitting is formed.

Claims (16)

A metal corrosion inhibitor containing at least one compound selected from the group consisting of imidazole, thiazole and triazole having at least one group selected from the group consisting of amino and thiol groups in the molecule. The corrosion inhibitor according to claim 1, wherein the imidazole having at least one amino or thiol group in the molecule is 2-mercaptoimidazoline or 2-mercapto-1-methylimidazole. The corrosion inhibitor according to claim 1, wherein the thiazole having at least one amino or thiol group in the molecule is 2-mercaptothiazoline or 2-aminothiazole. The method of claim 1, wherein the triazole having at least one amino or thiol group in the molecule is 3-aminotriazole, 4-aminotriazole, 2,5-diaminotriazole, 3-mercaptotriazole or 3- A corrosion inhibitor which is amino-5-mercaptotriazole. A corrosion inhibitor for copper or copper alloy containing at least one compound selected from the group consisting of imidazole, thiazole and triazole having at least one group selected from the group consisting of amino groups or thiol groups in the molecule. A corrosion inhibitor for copper wiring of a semiconductor device, comprising at least one compound selected from the group consisting of imidazole, thiazole and triazole having at least one group selected from the group consisting of amino groups or thiol groups in the molecule. A cleaning liquid composition comprising the corrosion inhibitor for metal according to claim 1 and a cleaning liquid. 8. A composition according to claim 7, wherein said cleaning liquid is a basic solution. The composition according to claim 8, wherein the basic solution is ammonia water. 8. A composition according to claim 7, wherein said cleaning liquid is an acidic solution. The cleaning liquid composition for semiconductor elements which has metal wiring containing the metal corrosion inhibitor and cleaning liquid of Claim 1. The cleaning liquid composition for semiconductor elements which has copper wiring containing the metal corrosion inhibitor and cleaning liquid of Claim 1. A method for cleaning a metal comprising washing the metal with the cleaning liquid composition according to claim 7. A method for cleaning a semiconductor device having metal wiring, which comprises cleaning the semiconductor device with the cleaning liquid composition according to claim 7. 15. The method of claim 14, wherein the metal wiring is copper wiring. A method for cleaning a semiconductor device having copper wiring, comprising the step of cleaning the semiconductor device with an aqueous solution containing 0.001 to 10% by weight of ammonia and 0.0001 to 10% by weight of the metal corrosion inhibitor according to claim 1.