JPS5884974A - Etching agent composition - Google Patents

Abstract

PURPOSE:To obtain an etching agent composition increasing the etching speed of semiconductive silicon, etc. by adding a specified diamine contg. fluorine or a salt thereof to a soln. contg. hydrogen fluoride and ammonium fluoride. CONSTITUTION:This etching agent composition consists of a diamine contg. fluorine or a salt thereof represented by the general formula (where Rf is 5- 20C fluoroalkyl, each of R1, R2 and R3 is H, 1-4C alkyl or hydroxyalkyl, X is H or methyl, Y is H or F, and A is substituted alkylene), hydrogen fluoride, ammonium fluoride and water. In the composition the diamine and salt are used by about 0.0001-5wt% of the total amount of the composition in general. By the composition the wetting property of the etching soln. is improved without deteriorating the advantage, so the etching soln. penetrates easily into the fine gaps of a resist film and increases the etching speed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an etching agent composition, and more particularly to an etching agent composition containing a specific fluorine-containing diamine or a salt thereof as a surfactant.

When semiconductor silicon is wet etched, hydrofluoric acid is currently commonly used as the etching agent.

For the purpose of etching, methods have been proposed that use a mixture of hydrofluoric acid and nitric acid (Japanese Patent Publication No. 55-48696) and a method that uses a mixture of hydrofluoric acid and ammonium fluoride. . This ammonium fluoride has the function of adjusting the etching rate and also stabilizing the etching rate even if the concentration of hydrofluoric acid changes.Usually, 1 weight of 50% hydrofluoric acid is used. 5 parts by weight or more of the 40% ammonium fluoride aqueous solution. However, when such a large amount of ammonium fluoride is mixed, there is a problem that the surface tension of the etching solution increases, resulting in extremely poor wettability on the silicon semiconductor or resist film to be etched. This causes a problem, mainly when extremely fine and complicated etching is required for integrated circuits and the like, because it is difficult for the etching solution to enter the minute gaps created in the resist film.

Therefore, it is thought that a fluorine-based surfactant can lower the surface tension of an etching solution containing ammonium fluoride, but ammonium fluoride has been found to be effective.

As a result of various studies, the present inventors have discovered that a specific fluorine-containing diamine or its salt can be advantageously used for hydrogen fluoride and liquids, and can sufficiently increase the etching rate, and have completed the present invention. did.

That is, the gist of the present invention is the general formula: % formula %] [wherein R is a fluoroalkyl group having 5 to 20 carbon atoms;
R1, R2 and R3 are the same or different and are hydrogen or an alkyl group having 1 to 4 carbon atoms or a hydroxyalkyl group; X is hydrogen or a methyl group; Y is hydrogen or fluorine; A is alkylene which may have a substituent represents a group. ] An etching agent composition comprising a fluorine-containing diamine or a salt thereof, hydrogen fluoride, ammonium fluoride, and water.

The fluoroalkyl group represented by the above general formula CI]'+, Rf refers to a saturated or unsaturated, straight-chain or branched, substituted or unsubstituted alkyl group containing fluorine; It also includes those in which an oxygen atom is interposed between the bonds. A preferable fluorine-containing alkyl group is a group having 5 to 20 carbon atoms and/or a group having at least as many fluorine atoms as carbon atoms in the group.

When R, R, and 几 are alkyl groups, if the number of carbon atoms is 5 or more, the solubility of the fluorine-containing diamine tends to deteriorate, which is not preferable.

゛Also, the number of carbon atoms in A is usually preferably 2 to 4.

Substituents that the group A may have include those having 1 to 8 carbon atoms;
Preferable examples include an alkyl group, a hydroxyl group, or a lower alkoxy group.

Examples of the acid that forms a salt with the fluorine-containing diamine [1] include inorganic acids such as hydrochloric acid, hydroiodic acid, and nitric acid, and lower aliphatic carboxylic acids such as formic acid, acetic acid, propionic acid, and propionic acid. However, it is not preferable to use an inorganic acid containing metal ions, such as potassium hydrogen sulfate, because there is a risk of adversely affecting the electrical properties of the material to be etched.

Among the acids that can be used, hydrochloric acid is the most preferred from the viewpoints of solubility and surface tension lowering performance, as well as from the viewpoint that it does not affect the material to be etched.

Examples of preferable fluorine-containing diamine [1] and its salts used in the present invention are as follows: Hydrochloride of compound (1) (2) Nitrate of compound (3) (4) Compound (
Acetate salt of (5) (6) Compound (7)
) formate (8) ＼ C2H,OH Hydroiodide of compound (9) (10) Hydrochloride of compound (11) (12) These compounds are, for example, compounds represented by the general formula: % formula %] It can be produced by reacting a diamine represented by the general formula: and by a conventional method.

The compound of the present invention may be used in combination with other fluorine-containing surfactants or fluorine-free surfactants, if necessary. A preferable example of the fluorine-containing surfactant used in combination is a patent application 1984 surfactant, especially n4 CH2CH
2NHC3H6N (CH,), and its hydrochloride.

The fluorine-containing diamine [1] and its salt used in the present invention do not contain metals such as potassium, sodium, and calcium in the molecule, so they are compounds that do not have a negative electrical effect on semiconductor materials. be.

The etching agent composition of the present invention can be prepared by simply mixing each component, and there is no restriction on the order of addition. For example, a method of dissolving the necessary amount of fluorine-containing diamine [I''l or its salt in either hydrofluoric acid or ammonium fluoride and then mixing the other; It can be prepared by mixing ammonium in advance and adding and dissolving the fluorine-containing diamine [1] or a salt thereof.

The amount of the fluorine-containing diamine [■] and its salt added is usually 0.0001 to 5% by weight, preferably 0.001 to 0.1% by weight, based on the total composition. If the amount is less than the above lower limit, the effect of addition will hardly be recognized; on the other hand, 5% by weight
Even if a larger amount is added, a commensurate effect cannot be obtained, which is disadvantageous.

The ratio of hydrofluoric acid and ammonium fluoride may be as conventional, for example, 5 parts by weight or more of a 40% aqueous ammonium fluoride solution to 1 part by weight of 50% hydrofluoric acid.

The etching agent composition of the present invention is produced by adding fluorine-containing diamine CD and its salt to an etching solution containing a mixture of hydrofluoric acid and ammonium fluoride, without impairing the advantages of the etching solution. , which has improved wettability, making it easier to penetrate into the fine gaps in the resist film. Therefore, it has the notable advantage that materials to be etched with narrow gaps in the resist film and materials to be etched with wide gaps can be processed at the same etching rate.

Next, examples will be shown to specifically explain the present invention.

Examples 1 to 4 and Comparative Examples 1 to 2 (Surface Tension Test) The above compound ( 2) (However, the Rf group is C1l"
l11), Compound (4) (However, the Rf group is 08K7
), Compound (8) (wherein R (the group is C11FI9) was added in an amount of 0.01% by weight) to prepare an etching composition.

The surface tension of the composition at 25C was measured by the Daigne method. In addition, for comparison, measurements were also made in the case where no fluorine-based surfactant was added, and in the case where C0F19COOK was added. The results are shown in Table 1.

Note) The solubility of CsF, C00K in the above mixed solution is low, and does not dissolve up to 0.01% by weight.

Examples 5 to 6 and Comparative Example 8 (Etching rate accelerating effect test) One ton of the etching composition prepared using compound (2) or compound (6) in Example 1 was coated with a thickness of about 100 OA by thermal oxidation method. produced an S+02 film of diameter 5
A 0fi silicon wafer was immersed at 25C for 1 minute.

After immersion, the wafer was taken out, washed with water, and visually observed. In both cases of compounds (2) and (6), the entire surface of the silicon was glossy, indicating that 8i0
．． It was found that the membrane was completely removed. For comparison, the same operation as in Example 5 was performed except that no fluorosurfactant was added.

As a result of visual observation, 840. 8s due to surface color change
Although it was recognized that the surface layer portion of the 02 membrane had been removed, it was not completely removed.

Patent applicant: Daikin Industries, Ltd. Representative Patent Attorney Aoyama Ao (and 2 others)

Claims (1)

[Scope of Claims] ＼ 3 [In the formula, R is a fluoroalkyl group having 5 to 20 carbon atoms:
R1s ``2 and 几 are the same or different hydrogen or an alkyl group having 1 to 4 carbon atoms or a hydroxyalkyl group: X is hydrogen or a methyl group; Y is hydrogen or fluorine; A may have a substituent represents an alkylene group.] An etching agent composition comprising a fluorine-containing diamine or its salt, hydrogen fluoride, ammonium fluoride, and water. 2. The amount of the fluorine-containing diamine or its salt added to the total composition 8. The composition according to claim 1, wherein the salt is a salt with an inorganic acid or a lower aliphatic carboxylic acid. 4. The composition according to claim 8, wherein the inorganic acid is hydrochloric acid, hydroiodic acid, or nitric acid. 5. The composition according to claim 8, wherein the lower aliphatic carboxylic acid is formic acid, acetic acid, or propionic acid. Composition according to item 8.