JP2003193272A - Method of etching film with molybdenum as major component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of etching a film with molybdenum as the main component which is used for forming molybdenum wiring used for a semiconductor element, a semiconductor integrated circuit, a liquid crystal panel or the like. <P>SOLUTION: A molybdenum-containing film is brought into contact with an oxidizer which can oxidize molybdenum, and etching is performed thereto. Next, the film is brought into contact with an organic alkali solution. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to etching of a film containing molybdenum as a main component used for forming a molybdenum wiring used in a semiconductor element, a semiconductor integrated circuit, a liquid crystal panel or the like.

[0002]

2. Description of the Related Art High melting point metal materials such as molybdenum and low electric resistance materials are widely used as semiconductor integrated circuits such as LSI (high density integrated circuits) and gate electrode materials and wiring materials of TFT (thin film transistor) elements. There is.

Since molybdenum is a metal that is easily oxidized, it has the property of forming molybdenum oxide on the surface of molybdenum when exposed to an atmosphere containing oxygen, water vapor, etc. during the formation process. In many cases, molybdenum oxide often forms at the interface between the substrate and molybdenum. Not all types of molybdenum oxide have been clarified,
Known ones include MoO ₃ , Mo ₁₈ O ₅₂ , Mo ₉ O ₂₆ ,
Mo ₈ O ₂₃ , Mo ₅ O ₁₄ , Mo ₁₇ O ₄₇ , Mo ₄ O ₁₁ , Mo ₄
Examples include O ₁₁ and MoO ₂ .

As a method for etching molybdenum, wet etching is generally performed using an etching solution containing nitric acid and phosphoric acid. However, if molybdenum oxide is formed on the surface of the molybdenum film due to a chemical reaction with oxygen or moisture, the etching solution containing nitric acid and phosphoric acid has a faster taper rate to molybdenum than molybdenum oxide, and thus a smooth taper is formed. There is a problem that cannot be obtained.

Since the etching difference between molybdenum and molybdenum oxide is relatively small as compared with an etching solution containing nitric acid and phosphoric acid, there is a method of etching by contact with hydrogen peroxide solution (Japanese Patent Laid-Open No. 3-266426). . However, a part of molybdenum oxide generated by contact with hydrogen peroxide solution is less soluble in hydrogen peroxide than molybdenum, and there is a problem that molybdenum oxide cannot be etched and remains.

Another method is to remove molybdenum oxide produced by contact with hydrogen peroxide by contacting it with hydrochloric acid or hydrobromic acid after etching with hydrogen peroxide solution (JP-A-10-107015). Hydrochloric acid and hydrobromic acid have a problem that they are inconvenient to handle because they are highly corrosive to metals and concrete and may corrode equipment materials.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for etching a film containing molybdenum as a main component, which solves the above problems.

[0008]

Means for Solving the Problems As a result of intensive studies to solve the above problems, a step of wet etching a film containing molybdenum as a main component with an oxidizing agent capable of oxidizing molybdenum, and including an organic alkali The inventors have found a method of etching and removing a film containing molybdenum as a main component by combining the steps of wet etching with an etching solution, and arrived at the present invention. That is, the present invention relates to a method of etching a film containing molybdenum as a main component, which comprises contacting a film containing molybdenum with an oxidant and then contacting the film with an organic alkaline solution. Is.

[0009]

DETAILED DESCRIPTION OF THE INVENTION An oxidizer capable of oxidizing molybdenum
And then KMnO_Four, MnO₂, Mn (CH₃CO ₂)₃Such as
Manganese compound, CrO₃, Na₂Cr₂O₇Such as chrome
Compound, Cl₂, Br₂, I₂, NaClO, KBrO_Four,
KIO_FourSuch as halogen and its compounds, HNO₃, HN
O₂, N₂O₃, N₂O_FourInorganic nitrogen compounds such as O₃Such as
Oxygen, hydrogen peroxide, Na₂O₂Peroxides such as CH₃
CO₃H, K₂S₂O₈Peroxo acids such as FeCl₃,
Fe₂(SO_Four)₃Metal compounds such as
However, for low environmental impact, handling, semiconductors, liquid crystals, etc.
Hydrogen peroxide is preferred from the point of use.

When hydrogen peroxide solution is used, the concentration is preferably 40% by weight or less. If the hydrogen peroxide concentration becomes low, it will take a long time for etching. On the contrary, if the concentration is high, the etching time becomes short. By setting the hydrogen peroxide concentration to 40% by weight or less, peeling of the resist due to overetching for a long time can be prevented. The hydrogen peroxide-containing solution may be added with an additive such as an acid, an alkali, a chelating agent, a surfactant, and an anticorrosive agent of various materials, in addition to the hydrogen peroxide solution.

When molybdenum etching is performed using a solution of hydrogen peroxide alone, the hydrogen ion concentration of hydrogen peroxide water changes due to the generated molybdic acid, and the etching rate of molybdenum changes. Difficult to do. Also, if the hydrogen peroxide solution is kept alkaline, the stability of hydrogen peroxide will be impaired,
It is difficult to maintain stable etching ability. Therefore, it is preferable to control the hydrogen ion concentration of the hydrogen peroxide aqueous solution with an acid.

When the treatment temperature is high, the hydrogen peroxide solution is easily decomposed and the liquid life is shortened. In some cases, hydrogen peroxide is concentrated and there is a danger of explosion. On the other hand, if the temperature is too low, the etching time is delayed and it is not efficient. Therefore, the etching temperature is preferably 20 to 40 ° C.

The organic alkali used in the second step of the present invention includes quaternary ammonium hydroxide or salts thereof, amines such as ethanolamine and triethanolamine,
Examples include amidines such as guanidine, and 1,8-bis (dimethylamino) naphthalene, which is generally called a proton spoid. Among them, quaternary ammonium hydroxide or salts thereof can effectively remove molybdenum oxide. Examples of the quaternary ammonium hydroxide or salts thereof include tetramethylammonium hydroxide, tetramethylammonium chloride, tetramethylammonium bromide, tetramethylammonium bromide, tetramethylammonium iodide, tetrabutylammonium hydroxide and tetrabutylammonium chloride. ,
Examples thereof include tetrabutylammonium bromide, tetrabutylammonium iodide, choline and the like. More preferably, the use of tetramethylammonium hydroxide is effective in removing molybdenum oxide.

When the quaternary ammonium hydroxide or its salt is used in the second step, an anticorrosive, an acid or an alkali may be added to the solution as an additive. However, since the sufficient effect cannot be obtained when the hydrogen ion concentration is neutral or lower, it is preferable that the liquid is alkaline. The concentration of tetramethylammonium hydroxide used in the present invention is preferably 30% by weight or less. If the concentration of tetramethylammonium hydroxide is too high, for example, when the resist is applied on the molybdenum film, it may peel off. Further, it is preferable to use it at a low concentration in view of cost and environmental load.

The temperature for etching with quaternary ammonium hydroxide is 80 ° C. or lower. If the temperature is too high, when the resist is coated on the molybdenum film, the resist is easily dissolved, which is not preferable.

[0016]

EXAMPLES The present invention will be specifically described below by experiments and comparative examples, but the present invention is not limited thereto.

Example 1 A molybdenum film having a pattern formed on a glass substrate was etched with molybdenum hydrogen peroxide solution. An aqueous solution containing 0.5% by weight of sulfuric acid with a hydrogen peroxide concentration of 6% by weight was used. The glass substrate is 1 cm long,
The width was cut into 1 cm and etching was evaluated. The structure of the substrate is shown in Figure 1, a). A glass container containing 50 g of the hydrogen peroxide solution was immersed in a constant temperature bath set at 40 ° C. to heat the hydrogen peroxide solution. A glass substrate cut into an aqueous hydrogen peroxide solution heated to 40 ° C. was put, and the time until molybdenum was etched was measured. After the etching with the aqueous hydrogen peroxide solution was completed, the substrate was thoroughly washed with pure water and nitrogen gas was used to remove water on the glass substrate. Next, 0.5%
The molybdenum oxide film remaining on the surface of the glass substrate was removed using a tetramethylammonium hydroxide aqueous solution having a concentration. The treatment temperature was room temperature, and the treatment time was 30 seconds. After the molybdenum oxide film was etched, it was thoroughly washed with pure water and the moisture on the glass substrate was removed with nitrogen gas.
The cross section of the glass substrate from which water was sufficiently removed was observed with a scanning electron microscope to evaluate the etching state of molybdenum. The evaluation results are shown in Table 1. An observation view after the treatment is shown in FIG. 1, b).

Examples 2 to 5 Example 1 except that an organic alkali other than tetramethylammonium hydroxide was used for the alkali treatment in the second step.
I went in the same way. The evaluation results are shown in Table 2.

Examples 6 to 8 Etching was performed in the same manner as in Example 1 except that the hydrogen peroxide concentration and etching temperature used in the first step were changed.

Examples 9 to 10 Etching was performed in the same manner as in Example 1 except that the concentration of tetramethylammonium and the etching temperature were changed.

Comparative Examples 1-2 Etching was carried out in the same manner as in Example 1 except that the organic alkali used in the second step was changed to an alkali other than the organic alkali.

Comparative Example 3 The etching was carried out in the same manner as in Example 1 except that the etching treatment was not performed with the hydrogen peroxide solution in the first step, and the etching state was evaluated. As a result, the molybdenum film could not be etched.

Comparative Example 4 Molybdenum was etched in the same manner as in Example 1 except that the etching treatment with tetramethylammonium hydroxide was not performed in the second step, and the etching state was evaluated. As a result, molybdenum oxide on the surface of the glass substrate was etched. I couldn't. Figure 1 shows an observation view of the etching state.
C).

Comparative Example 5 Molybdenum and tungsten were investigated in the same manner as in Example 1 except that an alloy film having a molybdenum / tungsten ratio of 7: 3 patterned on a glass substrate was used. The alloy film and the oxide film of the alloy were etched in the same manner as in Example 1.

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

[Table 3]

[0028]

According to the present invention, molybdenum oxide can be effectively etched.

[Brief description of drawings]

[Figure 1] Observation view of glass substrate

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor, Ikemoto alone             6-1, 1-1 Shinjuku, Katsushika-ku, Tokyo Mitsubishi tile             The Chemical Research Institute Tokyo Research Center (72) Inventor Hide Oto             6-1, 1-1 Shinjuku, Katsushika-ku, Tokyo Mitsubishi tile             The chemical company Tokyo factory F-term (reference) 4K057 WA01 WB08 WE25 WK01 WN01                 5F043 AA26 BB18 GG02

Claims (3)

[Claims] 1. A film containing molybdenum as a main component, characterized in that a film containing molybdenum is brought into contact with an oxidizer capable of oxidizing molybdenum for etching, and then the film is brought into contact with an organic alkaline solution to etch a film containing molybdenum as a main component how to. 2. The etching method according to claim 1, wherein the oxidizing agent is hydrogen peroxide. 3. The etching method according to claim 1, wherein the organic alkaline solution is tetramethylammonium hydroxide.