JPS5853980A - Etching composition - Google Patents

Abstract

PURPOSE:The titled composition that is made by adding a specific fluorinated diamine or its salt to an etching solution containing hydrogen fluoride, ammonium fluoride and water, thus improving its wetting properties to facilitate the impregnation of the etching solution into fine gaps between resist films. CONSTITUTION:A fluorine-containing diamine of formulaI[Rf is 5-20C fluoroalkyl; R1, R2, R3 are H, 1-4C alkyl, hydroxyalkyl; A is (CH2)p, formula II formula III (P is 1-5; m is 1-5; R4 is H, 1-3C acyl); B is 2-4C alkylene which may be substituted]or its salt, preferably its hydrochloride, hydroiodide, nitrate or a salt of organic acid such as formic, acetic or propionic acid is added to an etching solution consisting of hydrogen fluoride, ammonium fluoride and water to give the objective composition. The content of the fluorine- containing diamine or its salt is preferably 0.0001-5wt% based on the total composition.

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.

Depending on the purpose of etching, ・A method using a mixture of hydrofluoric acid and nitric acid (Japanese Patent Publication No. 48696/1983)
A method of using a mixture of ammonium fluoride and hydrofluoric acid has been proposed. This ammonium fluoride is
It adjusts the etching rate and also stabilizes the etching rate even if the concentration of hydrofluoric acid changes.Usually, 40% fluoric acid is added to 1 part by weight of 50% hydrofluoric acid. The ammonium chloride aqueous solution is used in a proportion of 5 parts by weight or more. However, when ammonium fluoride is mixed in such a large amount, the surface tension of the etching solution increases, resulting in a problem that the wettability of the silicon semiconductor to be etched and the resist film 11 becomes extremely poor. This is a disadvantage mainly when extremely fine and complicated etching is required for integrated circuits, etc., because it is difficult for the etching solution to enter the fine gaps created in the resist film.

Therefore, it may be possible to reduce the surface tension of etching solutions containing ammonium fluoride by using fluorine-based surfactants, but since ammonium fluoride greatly impairs the solubility of surfactants, there are It has been found that the types of surfactants are very limited.

As a result of various studies, the present inventors have found that a specific fluorine-containing diamine or its salt can be advantageously used in an etching solution consisting of hydrogen fluoride, ammonium fluoride, and water.
Furthermore, we discovered that the etching speed could be sufficiently increased.
The invention has been completed.

That is, the gist of the present invention is the general formula: [wherein R (represents a fluoroalkyl group having 5 to 20 carbon atoms;
R1, R2 and 3 are the same or different and are hydrogen, an alkyl group having 1 to 4 carbon atoms, or hydro, and P is 1 to
m is an integer of 1 to 5; R4 is hydrogen or an acyl group having 1 to 3 carbon atoms; ); B represents an alkylene group having 2 to 4 carbon atoms which may have a substituent. ] An etching agent composition comprising a fluorine-containing diamine or a salt thereof, hydrogen fluoride, ammonium fluoride, and water.

In general formula [I'), 1 (fluoroalkyl group represented by 1) refers to a saturated or unsaturated, linear or branched, substituted or unsubstituted alkyl group containing fluorine. , those in which an oxygen atom is interposed between carbon-carbon bonds are also included. Preferred fluorine-containing alkyl groups have 5 to 20 carbon atoms and/or groups having fluorine in the number of carbon atoms or more. It is.

When kl, R2 and ni3 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.

Furthermore, when the number of carbon atoms, m and P of B exceed the upper limit shown above, the solubility of the compound is poor, and even if it is dissolved, a sufficient effect cannot be obtained.

Group A car (a]2), -1-CH2CH(OCOCH3
)CH2-1-Cl42CH(CH3)- Compound CI) is particularly preferred for its solubility and surface tension lowering performance.

Substituents that the group I3 may have include those having 1 to 1 carbon atoms;
Preferred examples include the alkyl group, hydroxyl group, and lower alkoxy group of No. 3.

Examples of acids that form salts with the fluorine-containing diamine CI) include inorganic acids such as hydrochloric acid, hydroiodic acid, and nitric acid, and lower aliphatic carboxylic acids such as formic acid, acetic 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 CI) and salts thereof used in the present invention are as follows: hydrochloride of compound (1) (2) nitrate of compound (3) (4) acetate of compound (5) (6) Formate of compound (7) (8) Hydrochloride of compound (9)
00 Hydroiodide salt of compound (11) 04 Hydrochloride salt of compound 04
(14) Nitrate of compound 0υ
0 → Hydrochloride of compound αη
Q8J These main compounds and their production methods are detailed in JP-A-56-18944.

The fluorine-containing diamine [■] 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 risk of electrically adversely affecting the semiconductor side slope. It is.

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 in which the required amount of fluorinated diamine [■] or its salt is dissolved in either hydrofluoric acid or ammonium fluoride and then mixed with the other, or a method in which hydrofluoric acid and ammonium fluoride are mixed together. It can be prepared by mixing in advance, and adding and dissolving the fluorine-containing diamine [■] or its salt.

The amount of the fluorine-containing diamine CI) 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 is hardly recognized; on the other hand, 5% by weight
Even if a larger amount is added, the corresponding 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 a fluorine-containing diamine [■] and its salt to an etching solution containing a mixture of hydrofluoric acid and ammonium fluoride, without impairing the advantages of the etching group. , which has improved wettability, which allows it to penetrate into the fine gaps of the resist film.

It is something that Therefore, it has the remarkable advantage that materials to be etched having narrow gaps in the resist film and materials to be etched having 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) (Tatashi, +(f group is 09F
09), Compound (4) (However, R (group is 68F17)
, compound GO (however, R (group is C9F□9)) or compound 0υ (however, R (group is 07F1.) is each 0.0
An etching composition containing 1% by weight was prepared.

The surface tension of the composition at 25°C was measured by the Daigne method. For comparison, measurements were also made in the case where no fluorine-based surfactant was added and in the case where C9F19COOK was added. Results: Note) The solubility of 69F19COOK in the above mixed solution is low, with only 0.01% by weight being dissolved.

Examples 5 to 6 and Comparative Example 3 (Etching rate accelerating effect test) 1 g of the etching composition prepared using Compound (2) or Compound 00 in Example 1 was coated with S having a thickness of about 1000 A by a thermal oxidation method. + 02 diameter produced membrane 50
A silicone wafer made of sake was immersed at 25°C for 1 minute. After immersion, the wafers were taken out, washed with water, and visually observed. In both cases of compound (2) and 00, the entire surface was a glossy silicone surface, indicating that the 5in2 film had been completely removed. I understand. For comparison,
The same operation as in Example 5 was carried out except that the fluorosurfactant was not added.

As a result of visual observation, it was recognized that the surface layer portion of the 5I02 film had been removed due to a color change in the S r 02 surface, but it was not completely removed.

Patent Applicant Uto, representative of Taigin Kogyo Co., Ltd. Patent Attorney Ao 111 Tamotsu (and 2 others) (Monday) November 24, 1980 Commissioner of the Japan Patent Office: 1, 11 7 ■Indication of the case 1988 Patent Application No. 152413 No. 2 Name of the invention Etching agent composition 3 Relationship with the person making the amendment Patent applicant address Osaka 111 Osaka City If, Ward Umeyo 1'J-1.11
2i1i39 New Hankyu Building Name (285) Daigyun Kegyo 1'l <Shikikaihi Representative Yama 1) Minoru 4, Agent 5 Date of amendment order (voluntary) 7 Details of the invention in the statement of contents of the amendment Please correct the following parts of the explanation.

(1) Page 11, 2 lines, "Shika" is completely deleted.

that's all

Claims (1)

[Scope of Claims] [In the formula, R (represents a fluoroalkyl group having 5 to 20 carbon atoms;
1, R2 and 3 are the same or different hydrogen, an alkyl group having 1 to 4 carbon atoms, or hydro, and P is 1
m is an integer of 1 to 5; R4 is hydrogen or an acyl group having 1 to 3 carbon atoms; ); B represents an alkylene group having 2 to 4 carbon atoms which may have a substituent. ] An etching agent composition comprising a fluorine-containing diamine or a salt thereof, hydrogen fluoride, ammonium fluoride, and water. 2. The composition according to claim 1, wherein the amount of the fluorine-containing diamine or its salt added is 0.0001 to 5% by weight based on the total composition. 3. 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 3, wherein the inorganic acid is hydrochloric acid, hydroiodic acid or nitric acid. 5. The composition according to claim 3, wherein the lower aliphatic carboxylic acid is formic acid, acetic acid, or propionic acid.