JPH1088352A - (fluoroalkoxy)(alkoxy) silane compound and its production and preparation of fluorine-contained silicon oxide film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel compd. for stably forming a fluorine-contained silicon oxide film as a low-dielectric constant interlayer insulating film of a semiconductor device by a CVD method. SOLUTION: The (fluoroalkoxy)(alkoxy) silane compd. is expressed by the formula: (R1 O)n Si(OR<2> )4-n [R<1> denotes 2 to 3C fluoroalkyl group having a straight chain or branch; R<2> denotes a methyl group or ethyl group; n=1 to 3]. Triethoxychlorosilane and 1, 1, 1, 3, 3,3-hexafluoroisopropanol of l.1equiv. are brought into reaction in the co-presence of ammonia and after by-produces are removed, the (hexafluoroisopropoxy) triethoxysilane is obtd. by distillation. A gaseous mixture composed of the compd./tetraethoxysilaned/ozone is sent onto a heated substrate and is deposited by cracking, by which the fluorine- contained silicon oxide film is obtained. The compd. has an adequate vapor pressure, is a stable liquid compd. having low corrosiveness and danger. Since the stable supply of this compd. is possible, the mass production of the fluorine- contained silicon oxide films by a CVD method is possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel alkoxysilane compound having a fluoroalkoxyl group, a method for producing the same, and a method for forming a fluorine-containing silicon oxide film by chemical vapor deposition using these compounds and an oxidizing gas as raw materials. It relates to a method of manufacturing.

[0002]

2. Description of the Related Art As semiconductor devices become more highly integrated, it is required to lower the dielectric constant of an interlayer insulating film in order to reduce the signal delay time. Among them, a fluorine-containing silicon oxide film (hereinafter referred to as a SiOF film) is effective, and its production method and characteristics are being actively studied. Conventionally, as a method for producing a SiOF film, SiH ₄ / SiF ₄ / oxidizing gas or Si
A method of performing plasma CVD in a system of (OC ₂ H ₅ ) ₄ / C ₂ F ₆ / oxidizing gas has been mainly studied. Here, examples of the oxidizing gas include O ₂ , O ₃ , and N ₂ O. In addition, in the 43rd Applied Physics-related Lectures (March 26, 1996), HSi (OC ₂ H ₅ ) _{3
/ FSi (OC 2 H 5)} 3 / O 2 based plasma CVD
(26p-N-7, Toa Gosei, Hattori et al.) And Si (OC _{2
H 5) 4 / (CF 3} ) 2 CHOH / O 3 an atmospheric pressure CVD of
(26p-N-4, NTT) Ikeda et al.) Discloses a method for producing a SiOF film. However, at the time of film formation even in CVD,
Si (OC) which is expected to have flow characteristics and stable supply during deposition
(Fluoroalkoxy) (alkoxy) silanes such as H (CF ₃ ) ₂ ) (OC ₂ H ₅ ) ₃ are unknown compounds, and there is no method for producing an SiOF film by CVD using these compounds.

[0003]

At present, Si (OC ₂ H ₅ ) ₄ is most commonly used as a CVD raw material for forming a silicon oxide film. If an SiOF film is made of a compound having physical properties close to this compound and being stable in handling, its industrial value is great. As the F source, a compound which is liquid at normal temperature and has a vapor pressure is preferable, not a gas such as chlorofluorocarbon. In addition, if Si and F are contained in one molecule, control of the film composition can be facilitated. One of these is S
Compound in which F atom is directly bonded to i atom, for example, FSi
There is (OC ₂ H ₅ ) ₃ , which reacts easily with moisture and air and easily changes in quality.
It is not industrially sufficient and unsatisfactory.

An object of the present invention is to provide a novel compound for stably forming a fluorine-containing silicon oxide film as a low dielectric constant interlayer insulating film of a semiconductor device by a CVD method.

[0005]

Means for Solving the Problems The inventors of the present invention have been developing Si for many years.
Research has been continued on the formation of a silicon oxide film using (OC ₂ H ₅ ) ₄ . A compound in which one ethoxy group of Si (OC ₂ H ₅ ) ₄ was substituted with a fluoroalkoxyl group was not known, but it was thought to be effective in solving the above-mentioned problem, and the compound was synthesized and its physical properties were determined. Was measured, and when a film was formed by CVD, it was found that a SiOF film could be stably formed, and the present invention was completed. That is, the present invention provides (R ¹ O) _n Si (OR ² ) _4-n as a raw material compound for forming a SiOF film by a CVD method.
[Wherein, R ¹ represents a linear or branched fluoroalkyl group having 2 to 3 carbon atoms, R ² represents a methyl group or an ethyl group, and represents that n = 1 to 3]. To provide a novel (fluoroalkoxy) (alkoxy) silane compound. This new compound is more stable against moisture and air since the F atom is not directly bonded to the Si atom. In addition, it is considered that the effect on the human body is small.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The formula [I] (R ¹
In O) _n Si (OR ² ) _4-n , examples of the linear or branched fluoroalkyl group having 2 to 3 carbon atoms represented by R ¹ include a 2,2,2-trifluoroethyl group , 1,1,1,3,3,3-hexafluoroisopropyl group and the like.

The compounds represented by the formula [I] in the present invention include, specifically, (2,2,2-trifluoroethoxy) triethoxysilane, bis (2,2,2-trifluoroethoxy) Diethoxysilane, (1,1,1,
3,3,3-hexafluoroisopropoxy) triethoxysilane, bis (1,1,1,3,3,3-hexafluoroisopropoxy) diethoxysilane and the like.

In the present invention, the compound represented by the formula [I] is represented by Cl _n Si (OR ² ) _4-n [II] wherein R ² represents a methyl group or an ethyl group, and n = 1
To 3] with a fluoroalkyl alcohol in the presence of ammonia.

According to the present invention, compound [II] and its C
1 to 1 to 1.2 equivalents of a fluoroalkyl alcohol is reacted in an inert solvent such as toluene in the presence of ammonia at an appropriate temperature of -20 to 30 ° C for 0.5 to 5 hours. Then, the compound [I] is obtained by post-treatment and distillation by a conventional method.

The chemical formula and physicochemical properties of the compound [I] of the present invention are shown below. This compound is the compound obtained in Example 1. Molecular formula ((CF ₃ ) ₂ CHO) Si (OC ₂ H ₅ ) ₃ Properties Colorless and transparent liquid Melting point −20 ° C. or less Boiling point 165 to 167 ° C. (approximate to the boiling point of Si (OC ₂ H ₅ ) ₄ at 169 ° C.) ¹ H -NMR spectrum; δ (CDCl ₃ ): 1.2 ppm (t, J = 7.0 Hz, methyl proton) 3.9 ppm (q, J = 7.0 Hz, methylene proton) 4.6 ppm (sep, J = 5. 9 F, methine proton ¹⁹ F-NMR spectrum: (C ₆ F ₆ δ _F = 16
2.9 External standard) δ (CDCl ₃ ): -76.8 ppm (d, J = 5.7)
Hz, _CF 3). FT-IR spectrum; 1298, 1267, 123
2,1109,974,878,797,687cm
^-1 GC-MS (CI); (M + H) +331

The above compound is a liquid, and has a vapor pressure close to that of tetraethoxysilane Si (OC ₂ H ₅ ) ₄ , which is currently often used for forming a silicon oxide interlayer insulating film, so that it is mixed with tetraethoxysilane. It is also possible to provide a stable supply. Also, triethoxyfluorosilane FSi (OC in which F atoms are directly bonded to Si atoms)
Compared to the ₂ H _{5) 3,} easy to handle because it is stable to water and air. It is also preferable because it has low corrosiveness.

The present invention provides a compound of the formula [I]
It is also a method of forming a SiOF film by the VD method. By introducing the gas of the compound [I] of the present invention and the oxidizing gas onto a heated substrate and causing a decomposition reaction on the substrate surface, S
An iOF film can be formed. Depending on the desired film composition and structure, Si (OC ₂ H ₅ ) ₄ or Si (OCH ₃ ) ₄
May be supplied simultaneously. Compound [I] is a liquid,
Since the boiling point and vapor pressure are close to i (OC ₂ H ₅ ) ₄ and Si (OCH ₃ ) ₄ and the chemical properties are similar, the compound [I] is stably sent to the substrate and decomposed and deposited there. Can be. Examples of the oxidizing gas include oxygen O ₂ , ozone O ₃ , and nitrous oxide N ₂ O. Atmospheric pressure C
VD, low pressure CVD, plasma CVD and the like can be used.

[0013]

【Example】

Example 1 The compound of the formula [I] (1,1,1,3,3)
Production of 3,3-hexafluoroisopropoxy) triethoxysilane reflux condenser, gas injection tube, thermometer,
500 toluene was placed in an 11 four-necked flask equipped with a stirrer.
ml, triethoxychlorosilane Si (OC ₂ H ₅ ) ₃
29.0 g of Cl (boiling point: 156 ° C., 0.146 mol)
l), 26.5 g (boiling point: 59 ° C., 0.157 mol) of 1,1,1,3,3,3-hexafluoroisopropanol ((CF ₃ ) ₂ CHOH) were charged and cooled to 0 ° C. While cooling the flask while stirring the reaction solution, 3.3 Nl of dry ammonia gas NH ₃ (0 ° C., 1 atm, 0.147 mol) was blown through a blow tube. White crystals were precipitated at the same time as the start of blowing. After the completion of the blowing, the cooling was stopped, and the mixture was stirred and maintained at 25 to 30 ° C. for 4 hours. The reaction solution slurry was filtered to remove by-product ammonium chloride, and the solvent toluene was distilled off to obtain 30 g of a crude liquid. 30 g of this was charged into a small rectification apparatus, distillation was performed under atmospheric pressure, the first distillation was cut, and the top temperature was 16
19.5 g of a fraction exhibiting 5-167 ° C. were obtained. When this was quantified by gas chromatography (column: SE-30 / Chromosorb AW, detector: TCD), the main component was 91% and the rest was mainly Si (OC ₂ H ₅ ) ₄ .
The main component was identified by ¹ H-NMR) ¹⁹ F-NMR, FT-
It was confirmed by IR and GC-MS to be the title compound. Yield 17.7g (36% yield)

The equipment and conditions used for identification are as follows. NMR equipment; BRUCKER AC300P frequency; ¹ H
300.13MHz ¹⁹ F 282.41MHz solvent; CDCl ₃ Concentration: 20 mg / 0.4 ml pulse ^width; 1 H ^6μs, 19 F ^5μs temperature; room temperature FTIR instruments; SHIMADZU FTIR-8600 Resolution: ^{4 cm -1} wavenumber; 400- 4000 cm ^-1 method; liquid membrane method GC column; MEGABORE DB-1 0.53 mm ×
15m Injection temperature; 200 ° C Carrier gas; He 30ml
/ Min Column temperature; 120 ° C. MS instrument; HITACHI M-80B ion accelerating voltage;
3kV ionization method; chemical ionization method (positive)
Gas; isobutane mass range; M / Z = 0-500

Example 2 (1,1,1,3,3,1)
Production of SiOF film by CVD using 3-hexafluoroisopropoxy) triethoxysilane Using a gas of compound [I] / Si (OC ₂ H ₅ ) ₄ / O _3, a 2-inch silicon substrate was formed by a normal pressure CVD apparatus. A film was formed. Conditions feed gas and its supply quantity _{((CF 3) 2 CHO)} Si (OC 2 H 5) 3 5sccm Si (OC 2 H 5) 4 10sccm O 3 / O 2 30 / 70sccm Ar 50sccm obtained substrate temperature 400 ° C. In the FT-IR spectrum of the film, 940c
From the absorption at m- ¹ , it was found that a SiF bond was generated.

[0016]

The compound of the formula [I] of the present invention can stably form a SiOF film under CVD conditions. According to the present invention, a novel chemical substance capable of forming a SiOF film by CVD can be provided.

Claims (6)

[Claims] [Claim 1] _{^{(R 1 O) n Si (}} OR 2) 4-n [I] [ wherein, ^{R 1} represents a fluoroalkyl group having a linear or branched 2-3 carbon atoms, ^{R 2} Represents a methyl group or an ethyl group, and represents that n = 1 to 3]. 2. The method of claim 1, wherein R ¹ is 1,1,1,3,3,3-hexafluoroisopropyl and R ² is ethyl.
A compound as described. 3. Cl _n Si (OR ² ) _4-n [II] wherein R ² represents a methyl group or an ethyl group, and n = 1
Wherein the compound represented by formula (I) is reacted with a fluoroalkyl alcohol in the presence of ammonia. 4. The method according to claim 3, wherein R ² is ethyl and the fluoroalkyl alcohol is 1,1,1,3,3,3-hexafluoroisopropanol. 5. A method of forming a fluorine-containing silicon oxide film by chemical vapor deposition, comprising a step of contacting a substrate with a volatile silane compound and an oxidizing gas, wherein the silane compound is a compound of the formula (1) 1)). 6. The method according to claim 1, wherein the silane compound is (1,1,1,3,3).
6. A method according to claim 5, characterized in that it is 3,3-hexafluoroisopropoxy) triethoxysilane.