JP4479190B2 - Insulating film material comprising alkenyl group-containing organosilane compound, insulating film and semiconductor device using the same - Google Patents

Description

  The present invention relates to an insulating film material comprising an organosilane compound for plasma polymerization and its use. In particular, the present invention relates to a low dielectric constant interlayer insulating film material used in multilayer wiring technology in logic ULSI.

  In the manufacturing technology of the integrated circuit field of the electronics industry, there is an increasing demand for high integration and high speed. In silicon ULSIs, especially logic ULSIs, the performance of wiring connecting them is a problem rather than the performance due to miniaturization of MOSFETs. That is, in order to solve the wiring delay problem associated with the multilayer wiring, it is required to reduce the wiring resistance and between the wirings and the interlayer capacitance.

  For these reasons, instead of aluminum wiring, which is currently used in most integrated circuits, it is essential to introduce copper wiring with lower electrical resistance and migration resistance. The process of copper plating after seed formation by the CVD method is being put into practical use.

There are various proposals for low dielectric constant interlayer insulating film materials. As the prior art, silicon dioxide (SiO ₂ ), silicon nitride, phosphosilicate glass has been used for inorganic systems, and polyimide has been used for organic systems. Recently, however, a tetralayer has been previously prepared for the purpose of obtaining a more uniform interlayer insulating film. Hydrolysis of ethoxysilane monomer, that is, polycondensation to obtain SiO ₂ and proposal to use as a coating material called Spin on Glass (inorganic SOG), or polysiloxane obtained by polycondensation of organic alkoxysilane monomer to organic There are proposals for use as SOG.

  In addition, there are two methods for forming an insulating film: a coating type in which an insulating film polymer solution is applied by spin coating or the like, and a CVD method in which a film is formed mainly by plasma polymerization in a plasma CVD apparatus. .

  As a proposal of the PECVD method, for example, in Patent Document 1, a method of forming a trimethylsilane oxide thin film by plasma CVD from trimethylsilane and oxygen, and in Patent Document 2, such as methyl, ethyl, n-propyl, etc. There has been proposed a method of forming an alkyl silane oxide thin film from an alkoxy silane having an alkynyl and aryl group such as linear alkyl, vinyl and phenyl by PECVD. These conventional insulating films formed by plasma CVD method have good adhesion to barrier metal and copper wiring material as wiring material, but there are cases where film uniformity is a problem. In addition, the film formation requires high plasma power in order to realize a high film formation rate, such as high-power high-frequency power supply of several thousand watts (W), quartz or the like in the chamber for film formation. Expensive materials had to be used, and there were economic problems. Furthermore, since the film is formed with a high plasma power, it is difficult to control the structure of the thin film polymer to be produced, and the relative dielectric constant may be insufficient.

  Therefore, there is a demand for a material capable of forming a low dielectric constant insulating film at low film power and high film formation speed using an inexpensive apparatus.

  On the other hand, as a coating type proposal, although the uniformity of the film is good, three steps of coating, solvent removal, and heat treatment are necessary, which is economically disadvantageous than CVD materials, and barrier metal, wiring In many cases, adhesion to the copper wiring material, which is the material, and uniform application of the coating liquid to the miniaturized substrate structure itself are problems.

Moreover, in the coating type material, the method of using a porous material in order to implement | achieve the Ultra Low-k material whose relative dielectric constant is 2.5 or less and also 2.0 or less is proposed. Organic or inorganic material matrix readily disperse the thermally decomposed organic component particles in the method of heat treating and pore formation, silicon and oxygen by evaporating SiO ₂ ultrafine particles formed by evaporation in a gas, SiO ₂ than There is a method of forming a fine particle thin film.

  However, although these porous methods are effective for lowering the dielectric constant, the mechanical strength decreases, chemical mechanical polishing (CMP) becomes difficult, and the dielectric constant increases due to moisture absorption. And wiring corrosion could be caused.

  Therefore, the market further seeks well-balanced materials that satisfy all the required performance such as low dielectric constant, sufficient mechanical strength, adhesion to barrier metal, copper diffusion prevention, plasma ashing resistance, moisture absorption resistance, etc. . As a method for balancing these required performances to some extent, a material having an intermediate characteristic between an organic polymer and an inorganic polymer has been proposed in an organic silane material by increasing the carbon ratio of the organic substituent to silane.

  For example, in Patent Document 3, a coating solution obtained by hydrolytic polycondensation of a silicon compound having an adamantyl group in the presence of an acidic aqueous solution by a sol-gel method is used, and an interlayer having a relative dielectric constant of 2.4 or less without being made porous. A method for obtaining an insulating film is proposed.

  However, this material is a coating type material, and still has the problem of the film forming method using the coating type as described above.

JP 2002-110670 A

JP-A-11-288931 JP 2000-302791 A

  It is an object of the present invention to provide a novel low dielectric constant material, in particular, a low dielectric constant insulating film material comprising an alkenyl group-containing organosilane compound suitable for a PECVD apparatus, and including these insulating films. It is providing the semiconductor device which becomes.

  The present inventors have found that an organosilane compound having an alkenyl group is particularly suitable as a low dielectric constant interlayer insulating film material for a semiconductor device, and have completed the present invention.

  That is, the following general formula (1) having at least one alkenyl group

（式中、Ｒ^１，Ｒ^２は、炭素数１〜２０の炭化水素基を表し、ｎは０〜３の整数を表す。Ｒ^１，Ｒ^２は互いに結合していてもよい。）で示される有機シラン化合物を含んでなる、化学気相成長法により形成される絶縁膜用材料を提供することにある。

(Wherein R ¹ and R ² represent a hydrocarbon group having 1 to 20 carbon atoms, and n represents an integer of 0 to ^3. R ¹ and R ² may be bonded to each other). It is an object of the present invention to provide a material for an insulating film formed by a chemical vapor deposition method, comprising an organic silane compound.

  Details of the present invention will be described below.

In the general formula (1), R ¹ and R ² represent a saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms, and n represents an integer of 0 to 3. Further, those in which R ¹ and R ² are bonded to each other are also included in the scope of the present invention. When the number of carbon atoms exceeds 20, it may be difficult to procure the corresponding raw material or the purity may be low even if it can be procured.

  In consideration of stable use in a CVD apparatus, a hydrocarbon group having 1 to 10 carbon atoms is particularly preferable. When carbon number exceeds 10, the vapor pressure of the produced | generated organosilane compound may become low, and the use with a PECVD apparatus may become difficult.

Examples of the hydrocarbon group for R ¹ and R ² include, but are not limited to, alkyl groups having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, aryl groups, arylalkyl groups, and alkylaryl groups. Can be mentioned. R ¹ and R ² may be the same or different.

  For example, methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, tert. -Butyl, n-pentyl, tert. -Amyl, n-hexyl, cyclohexyl and the like can be mentioned.

  As unsaturated hydrocarbon groups, alkenyl such as vinyl, 1-propenyl, 1-butenyl and 2-butenyl, alkadienyl such as 1,3-butadienyl, 1,3-pentadienyl and 1,3-hexadienyl, ethynyl, 1- Examples thereof include alkynyl such as propynyl, 1-butynyl and 2-butynyl, aryl such as phenyl, and alkylaryl such as toluyl.

  In any case of the saturated hydrocarbon group and the unsaturated hydrocarbon, n in the chemical formula (1) is an integer of 0 to 3.

  Specific examples of the organic silane compound represented by the general formula (1) include tetravinylsilane, tetraisopropenylsilane, methyltrivinylsilane, dimethyldivinylsilane, trimethylvinylsilane, ethyltrivinylsilane, diethyldivinylsilane, triethylvinylsilane, phenyltri Vinyl silane, diphenyldivinylsilane, triphenylvinylsilane, isopropyltrivinylsilane, diisopropyldivinylsilane, triisopropylvinylsilane, sec-butyltrivinylsilane, disec-butyldivinylsilane, trisec-butylvinylsilane, tert. -Butyldimethylvinylsilane, tert. -Butylmethyldivinylsilane, tert. -Butylethyldivinylsilane, di-tert. -Butyldivinylsilane, tert. -Butyltrivinylsilane, etc. can be mentioned.

  Although the details of the mechanism of action of the organosilane compound having an alkenyl group of the present invention are unknown, it has a low dielectric constant insulation at a high film formation rate by chemical vapor deposition compared to conventional organosilane compounds. It is possible to form a film.

  Although the manufacturing method of the organosilane compound of the said General formula (1) is not specifically limited, For example, the hydrocarbon group substituted halogenated silane compound of the following General formula (2)

（式中、Ｒ^１及びｎは、上記一般式（１）に同じ。Ｘは、フッ素原子、塩素原子、臭素原子、沃素原子、炭素数１〜４のアルコキシ基を表す。）と、下記一般式（３）のアルケニル金属化合物

(Wherein R ¹ and n are the same as those in the general formula (1). X represents a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, or an alkoxy group having 1 to 4 carbon atoms) and the following general formula. Alkenyl metal compound of formula (3)

（式中、Ｒ^２は、上記一般式（１）に同じ。Ｍは、Ｌｉ、ＭｇＣｌ、ＭｇＢｒ、ＭｇＩを表す。）
を反応させ、製造することができる。

(In the formula, R ² is the same as in the general formula (1). M represents Li, MgCl, MgBr, and MgI.)
Can be made to react.

  Further, for example, an alkenyl group-substituted halogenated silane compound of the following general formula (4)

（式中、Ｒ^２及びｎは、上記一般式（１）に同じ。Ｘは、フッ素原子、塩素原子、臭素原子、沃素原子、炭素数１〜４のアルコキシ基を表す。）と、下記一般式（５）の有機金属化合物

(Wherein R ² and n are the same as those in the general formula (1). X represents a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, or an alkoxy group having 1 to 4 carbon atoms) and the following general formula. Organometallic compound of formula (5)

（式中、Ｒ^１は、上記一般式（１）に同じ。Ｍは、上記一般式（３）に同じ。）
を反応させ、製造することもできる。

(In the formula, R ¹ is the same as the above general formula (1). M is the same as the above general formula (3).)
Can also be made to react.

  In this production method, the production of by-products is suppressed, and an organic silane compound represented by the general formula (1) having a high purity and a high yield can be obtained.

  Reaction conditions of the hydrocarbon group-substituted halogenated silane compound of the general formula (2) and the alkenyl metal compound represented by the general formula (3), and the alkenyl group-substituted halogenated silane compound of the general formula (4) and The reaction conditions with the organometallic compound of the general formula (5) are not particularly limited, and are usually in the range of −100 to 200 ° C., preferably −85 to 150 ° C., which is an industrially used temperature. Preferably it is done. The pressure conditions for the reaction can be any of under pressure, normal pressure, and reduced pressure.

  The solvent used in the above reaction is not particularly limited as long as it is used in the technical field. For example, n-pentane, i-pentane, n-hexane, cyclohexane, n-heptane, n- Saturated hydrocarbons such as decane, unsaturated hydrocarbons such as toluene, xylene and decene-1, diethyl ether, dipropyl ether, tert. -Ethers such as butyl methyl ether, dibutyl ether, and cyclopentyl methyl ether can be used. Moreover, these mixed solvents can also be used.

  The alkenyl metal compound of the general formula (3) and the organometallic compound of the general formula (5) used in the production are the organic halide compounds of the following general formula (6)

（式中、Ｒ^３は、アルケニル基を含む炭素数１〜２０の炭化水素基を表し、Ｘは、上記に同じ。）と、金属リチウム粒子または金属マグネシウムとを反応させて製造することができる。

(In the formula, R ³ represents a hydrocarbon group having 1 to 20 carbon atoms including an alkenyl group, and X is the same as above) and can be produced by reacting metal lithium particles or metal magnesium. .

  Although the reaction conditions of the organic halide compound of the general formula (6) and the metal lithium particles or metal magnesium are not particularly limited, an example is shown below.

  As the metallic lithium to be used, lithium wire, lithium ribbon, lithium shot and the like can be used, but lithium fine particles having a particle diameter of 500 μm or less are preferably used from the viewpoint of reaction efficiency.

  As the metallic magnesium to be used, magnesium ribbon, magnesium particles, magnesium powder and the like can be used.

  The solvent used in the above reaction is not particularly limited as long as it is used in the technical field, and the solvents exemplified in the production of the organosilane compound of the general formula (1) can be used. . Moreover, these mixed solvents can also be used.

  About reaction temperature in said reaction, it is preferable to carry out in the temperature range which the organic lithium compound or organic magnesium compound to produce | generate does not decompose | disassemble. Usually, it is carried out in the range of −100 to 200 ° C., preferably −85 to 150 ° C., which is a temperature used industrially. The pressure conditions for the reaction can be any of under pressure, normal pressure, and reduced pressure.

  The synthesized alkenyl metal compound and organometallic compound can be used as they are after synthesis, and unreacted organic halide compound and metal lithium, metal magnesium, reaction by-product lithium halide, and magnesium halide are removed. It can also be used later.

  The method for purifying the organosilane compound represented by the above general formula (1) obtained by the above-described method is an element other than silicon, carbon, and hydrogen, having a moisture content of less than 50 ppm, useful for use as an insulating film material. In order to reduce the amount of impurities derived from the production raw material to less than 10 ppb, by-product lithium salt, magnesium salt, alkali metal salt is filtered using a glass filter, sintered porous body, etc., atmospheric pressure or reduced pressure distillation or silica It may be removed by means such as column separation and purification using alumina or polymer gel. At this time, these means may be used in combination as necessary. In a method of extracting by-product lithium salt, magnesium salt, alkali metal salt with water or the like as used in a general organic synthesis technique, the organic silane compound represented by the general formula (1) finally obtained Element impurities other than moisture, silicon, carbon, and hydrogen, especially metal impurity residues, may become high and may become inappropriate as an insulating film material.

  In the production, the method in the organometallic compound synthesis field is followed. That is, the dehydration and deoxygenation is performed in a nitrogen or argon atmosphere, and the solvent to be used and the column filler for purification are preferably subjected to dehydration operations in advance. It is also preferable to remove impurities such as metal residues and particles.

  The organosilane compound represented by the general formula (1) of the present invention is a material suitable for forming a film as a low dielectric constant insulating material by a PECVD apparatus.

  The method of using the insulating film material of the present invention is not particularly limited, but the PECVD apparatus generally used in the technical field such as the semiconductor manufacturing field and the liquid crystal display manufacturing field may be used to form the insulating film. it can. The PECVD equipment vaporizes an insulating film material such as an organosilane compound with a vaporizer, introduces it into a film forming chamber, applies it to an electrode in the film forming chamber with a high frequency power source, generates plasma, and forms a film. An apparatus for forming a plasma polymerized film on a silicon substrate or the like in a chamber. At this time, a gas such as argon or helium for the purpose of generating plasma, or a compound having at least one oxygen atom may be introduced for the purpose of introducing oxygen into the thin film.

  Compounds having at least one oxygen atom include oxygen, ozone, dinitrogen monoxide, water, hydrogen peroxide, alkoxysilane compounds, carbon dioxide, carbon monoxide, carboxylic acid, carboxylic acid peroxide, carboxylic acid Oxidizing materials such as peroxide esters can be mentioned.

  When a film is formed using the insulating film material of the present invention by a PECVD apparatus, a thin film suitable as a low dielectric constant material (low-k material) for semiconductor devices can be formed.

  A porous low dielectric constant insulating material can also be obtained by heat-treating these materials at a temperature higher than the bond between carbon atoms and silicon atoms is broken after film formation by CVD. The heat treatment temperature is preferably a temperature of 350 ° C. or higher at which the porosity is completed and 500 ° C. or lower at which the semiconductor device is not deteriorated.

  The low dielectric constant material of the present invention is suitable for the production of ULSI using multilayer wiring, and semiconductor devices using this material are also included in the scope of the present invention.

According to the present invention, the following remarkable effects are exhibited.
(1) By using the alkenyl group-containing organosilane compound having the structure of the present invention, an interlayer insulating film for a semiconductor device can be formed at a low relative dielectric constant and a high film formation rate.
(2) An alkenyl group-containing organosilane compound useful as a PECVD interlayer insulating film material can be efficiently produced with high purity.

  Examples are shown below, but the present invention is not limited to these Examples.

Reference example [Synthesis of vinylmagnesium chloride]
Under a nitrogen atmosphere, 552 g (22.7 mol) of magnesium and 4445 g (5.00 L) of tetrahydrofuran were charged into a 6 L four-necked flask reactor equipped with a reflux condenser, a dropping funnel and a stirrer, and 24.7 g of ethyl bromide. (0.227 mol) was added and stirred for 10 minutes. Thereafter, 1351 g of vinyl chloride gas was blown in for 10 hours to react. After blowing the vinyl chloride gas, the mixture was further stirred for 12 hours to obtain a 27.8 wt% (3.20 mol / kg) vinylmagnesium chloride tetrahydrofuran solution.

[Synthesis of tetravinylsilane]
Under a nitrogen stream, 493 g (2.90 mol) of silicon tetrachloride and 1422 g (1.60 L) of tetrahydrofuran were charged into a 6 L four-necked flask reactor equipped with a reflux condenser and a stirring device, and prepared above at room temperature. A 37.8 g (11.6 mol) tetrahydrofuran solution of 27.8 wt% (3.20 mol / kg) vinylmagnesium chloride was added dropwise over 3 hours. After completion of dropping, the mixture was further stirred at room temperature for 1 hour.

  The solid residue was filtered off with a glass filter to obtain a reaction mixture solution. Tetrahydrofuran was distilled off, and tetravinylsilane as the target product was isolated by distillation under reduced pressure.

  The yield was 184 g (1.35 mol), corresponding to a yield of 46.6%.

The results of analyzing the isolated tetravinylsilane by ¹ H-NMR, ¹³ C-NMR, and GC-MS were as follows.

¹ H-NMR; 5.80 to 6.26 ppm (m, 12H)
¹³ C-NMR; 134.7 ppm, 136.2 ppm
GC-MS; Mw = 136, C ₈ H ₁₂ Si
Further, the water content and potassium and lithium contents in 100 g of the obtained tetravinylsilane were measured using a Karl Fischer moisture meter and ICP-MS (high frequency plasma emission-mass spectrometer, manufactured by Yokogawa Analytical Systems, trade name “HP4500”). The results of measurement by H) were H ₂ O = 5 ppm and Mg <10 ppb, and were useful as insulating film materials.

[Plasma polymerization of tetravinylsilane]
Using a plasma polymerization apparatus NL-OP50FT manufactured by Nippon Laser Electronics Co., Ltd., discharge voltage 2.1 V, discharge current 3.0 mA, tetravinylsilane partial pressure 0.7 torr, oxygen partial pressure 0.03 torr, room temperature, polymerization (discharge) time Tetravinylsilane was subjected to plasma polymerization under conditions of 5 minutes, and a film was formed on a silicon substrate. Result is,
Deposition rate = 91.7 nm / min.
Thin film composition (XPS) C = 23.9 atom%, O = 51.1 atom%,
Si = 25.0 atom%
C / Si = 0.96 atom ratio
O / Si = 2.04 atom ratio SEM thin film cross-section observation It was a flat dense film.

Example 1
[Synthesis of Isopropyltrivinylsilane]
Under a nitrogen stream, 686 g (3.87 mol) of isopropyltrichlorosilane and 1422 g (1.60 L) of tetrahydrofuran were charged into a 6 L four-necked flask reactor equipped with a reflux condenser and a stirrer, and prepared above at room temperature. A solution of 3820 g (11.6 mol) of 0.88 wt% (3.20 mol / kg) of vinylmagnesium chloride in tetrahydrofuran was added dropwise over 3 hours. After completion of dropping, the mixture was further stirred at room temperature for 1 hour.

  The solid residue was filtered off with a glass filter to obtain a reaction mixture solution. Tetrahydrofuran was distilled off and the target product, isopropyltrivinylsilane, was isolated by distillation under reduced pressure.

  The yield was 441 g (2.90 mol), corresponding to a yield of 74.9%.

The results of analyzing the isolated isopropyltrivinylsilane by ¹ H-NMR, ¹³ C-NMR, and GC-MS were as follows.

¹ H-NMR; 1.091 ppm (s, 6H), 1.094 ppm (s, 1H),
5.77 ppm to 6.24 ppm (m, 9H)
¹³ C-NMR; 12.24 ppm, 17.64 ppm, 133.4 ppm
134.9 ppm
GC-MS; Mw = 152, C ₉ H ₁₆ Si
Further, the water content and potassium and lithium content in 100 g of the obtained isopropyltrivinylsilane were measured using a Karl Fischer moisture meter and ICP-MS (high-frequency plasma emission-mass spectrometer, manufactured by Yokogawa Analytical Systems, trade name “HP4500”). )), H ₂ O = 7 ppm, Mg <10 ppb, which was useful as an insulating film material.

Comparative Example 1
[Plasma polymerization of tetraethoxysilane]
Plasma polymerization was performed using a plasma polymerization apparatus NL-OP50FT manufactured by Nippon Laser Electronics Co., Ltd. under conditions of a discharge voltage of 2.1 V, a discharge current of 3.0 mA, a tetraethoxy partial pressure of 0.7 torr, room temperature, and a polymerization (discharge) time of 5 minutes. A film was formed on a silicon substrate. Result is,
Deposition rate = 37.5 nm / min.
Thin film composition (XPS) C = 53.6 atom%, O = 29.3 atom%,
Si = 17.1 atom%
C / Si = 3.13 atom ratio
O / Si = 1.71 atom ratio SEM thin film cross-sectional observation A flat dense film, and the film formation rate was as low as 41% of the film formation rate of tetravinylsilane in the reference example .

Claims (7)

A material for an insulating film formed by plasma enhanced chemical vapor deposition (PECVD) , comprising any of isopropyltrivinylsilane, diisopropyldivinylsilane, and triisopropylvinylsilane . Silicon, carbon, insulating film material according to claim 1, wherein the amount of impurities derived from a by a raw material an element other than hydrogen is less than 10 ppb, and a water content of less than 50 ppm. Claim 1 or 2 with insulation Enmaku material according to the insulating film deposited by PECVD apparatus. Insulating film according to claim 3, characterized in that a combination of compounds having at least one oxygen atom. A compound having at least one oxygen atom is oxygen, ozone, dinitrogen monoxide, water, hydrogen peroxide, an alkoxysilane compound, carbon dioxide, carbon monoxide, carboxylic acid, carboxylic acid peroxide, carboxylic acid peroxide The insulating film according to claim 4, wherein the insulating film is a product ester. An insulating film made porous by heat-treating the insulating film according to any one of claims 3 to 5 at a temperature at which the bond between carbon atoms and silicon atoms is broken. Semiconductor devices using an insulating film according to any one of claims 3 to 6.