JPH11288931A - Insulation film and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form an insulation film with a low permttivity, improved heat resistance and moisture resistance by using a silicon hydrocarbon compound that is expressed by a specific general expression as a material gas for forming the insulation film. SOLUTION: For forming an insulation film on a semiconductor substrate, first a silicon hydrocarbon compound whose generation expression is shown by Siα Oβ Cx Hy (where α, β, x, and y are integers) is vaporized directly as a material gas through a vaporization method. Then the gas is introduced into a reaction chamber 6 of a plasma CVD device 1. Then, an addition gas whose flow rate essentially has been reduced is introduced into the reaction chamber 6. Then, with the mixed gas between silicon hydrocarbon compound gas and the addition gas as a reaction gas, an insulation film is formed on a semiconductor substrate 4. By reducing the flow rate of the addition gas, the total flow rate of the reaction gas is essentially made to decrease. The obtained insulation film is extremely stable since it uses Si-O with a high total energy as a basic framework.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the manufacture of semiconductor devices, and more particularly to a silicon-based organic film formed by using a plasma CVD method and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, with the increasing demand for higher integration of semiconductor devices, multilayer wiring technology has attracted attention. The bottleneck of high-speed operation of the device in this multilayer wiring structure is
This is the capacitance between wires. In order to reduce the capacitance between wirings, it is necessary to lower the dielectric constant of the insulating film. Therefore, low dielectric constant insulating film materials have been developed.

A conventional silicon oxide film SiO _x used as an insulating film is obtained by adding O ₂ or N ₂ O as an oxidizing agent to a silicon material gas such as SiH ₄ or Si (OC ₂ H ₅ ) ₄ and applying heat and plasma. Manufactured using energy, its relative permittivity was about ε = 4.0.

On the other hand, an attempt has been made to produce a fluorinated amorphous carbon film by a plasma CVD method using C _X F _Y H _Z as a material gas. This insulating film achieves a low dielectric constant of a relative dielectric constant ε = 2.0 to 2.4.

Attempts have also been made to lower the dielectric constant of a film by utilizing the property of a highly stable Si—O bond. Using a material gas obtained by vaporizing P-TMOS (finyltrimethoxysilane) (chemical formula 1), a compound of benzene and silicon, by bubbling, a silicon-based organic film is formed at low pressure (1 Torr) by plasma CVD. It is to manufacture.
This insulating film achieved a low dielectric constant of ε = 3.1.

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Further, attempts have been made to lower the dielectric constant of the film by forming pores in the film and utilizing the porous structure. Inorganic SOG
An insulating film is manufactured using a material by a spin-coating method. This insulating film achieved a low dielectric constant of ε = 2.3.

[0007]

However, each of the above approaches has various disadvantages as described below.

First, the fluorinated amorphous carbon film has the disadvantages of low heat resistance (370 ° C.), poor adhesion to silicon-based materials, and low mechanical strength of the film.
If the heat resistance is low, there is a risk that the insulating film will be damaged in a high temperature process of, for example, 400 ° C. or more. If the adhesion is poor, there is a risk that the film will peel off. Further, when the mechanical strength of the film decreases, there is a risk that the wiring material may be damaged.

Next, in the P-TMOS film, the polymer formed in the gas phase does not grow linearly because the material P-TMOS has _three O-CH ₃ bonds, and the deposited film is Since it does not have a continuous porous structure (micropore structure), it has a disadvantage that the dielectric constant cannot be reduced to a certain degree or more. In addition, liquid
There is also a problem in that P-TMOS is vaporized by the bubbling method.

Here, the bubbling method is a method in which a vapor of a material obtained by passing a carrier gas such as an argon gas through a liquid material is introduced into a reaction chamber together with the carrier gas. In this method, a large amount of carrier gas is generally required to secure the flow rate of the material gas. As a result, the residence time of the material gas in the reaction chamber is shortened,
The polymerization reaction does not sufficiently occur in the gas phase.

Further, the SOG insulating film formed by the spin coating method has a problem of uneven application of a material on a substrate and a problem of a device cost used for a temperature control device in a curing process.

Accordingly, an object of the present invention is to provide an insulating film having a low dielectric constant, excellent heat resistance, moisture absorption resistance and adhesion, and a method for manufacturing the same.

Another object of the present invention is to provide a material for producing an insulating film having a low dielectric constant and excellent heat resistance, moisture absorption resistance and adhesion.

Still another object of the present invention is to provide a method for easily manufacturing an insulating film having a low dielectric constant without increasing the device cost.

[0015]

In order to achieve the above object, a method for forming an insulating film on a semiconductor substrate by using a plasma CVD apparatus according to the present invention comprises a general formula Si _α O
A silicon-based hydrocarbon compound represented by _β C _X H _Y (where α, β, x, and y are integers) is vaporized by a direct vaporization method,
A step of introducing an additional gas having a substantially reduced flow rate into the reaction chamber of the plasma CVD apparatus; and a step of using a mixed gas of the silicon-based hydrocarbon compound gas and the additional gas as a reaction gas. Forming an insulating film on the semiconductor substrate by a plasma polymerization reaction, wherein reducing the flow rate of the additive gas substantially reduces the total flow rate of the reaction gas.

Here, specifically, the silicon-based hydrocarbon compound has a chemical formula (A): (Where R1 and R2 are any of CH ₃ , C ₂ H ₃ , C ₂ H ₅ , C ₃ H ₇ , C ₆ H ₅ , and m and n are arbitrary integers). At least one compound.

In addition, the silicon-based hydrocarbon compound has a chemical formula (B): (Where R1, R2 and R3 are any of CH ₃ , C ₂ H ₃ , C ₂ H ₅ , C ₃ H ₇ , C ₆ H ₅ , and n is an arbitrary integer). May contain at least one compound.

In addition, the silicon-based hydrocarbon compound has a chemical formula (C): (Wherein, R1, R2, R3 and R4 _{are, CH 3, C 2 H 3} , C 2 H 5, C 3 H 7, C 6 H
₅ , and m and n are arbitrary integers. ) May be at least one compound.

In addition, the silicon-based hydrocarbon compound may have a chemical formula (D): (Where R1, R2, R3, R4, R5 and R6 are CH ₃ , C ₂ H ₃ , C ₂ H ₅ , C
₃ H ₇ or C ₆ H ₅ . ), And the additive gas is nitrogen oxide (N ₂ O) or oxygen (O ₂ ), argon (Ar) gas and / or helium (H).
e) It may be a gas.

Preferably, as a material gas in the chemical formula (D),
Further, it may contain at least one silicon-based hydrocarbon compound of the chemical formulas (A) and (B).

Specifically, the additive gas is argon (A
r) gas and / or helium (He) gas.

In addition, the additional gas may be hydrogen (H ₂ )
It may be gas and / or methane (CH ₄ ) gas.

Further, the additive gas may be a mixed gas of hydrogen (H ₂ ) gas and / or methane (CH ₄ ) gas and argon (Ar) gas and / or helium (He) gas.

The silicon-based hydrocarbon compound has a chemical formula (E): (Wherein, R1, R2, R3 and R4 _{are, CH 3, C 2 H 3} , C 2 H 5, C 3 H 7, C 6 H 5
Is one of At least one compound of the formula
And the additive gas is nitrogen oxide (N ₂ O) or oxygen
(O ₂ ), argon (Ar) and / or helium (He).

Further, as the material gas, the chemical formula (A),
It may also contain at least one silicon-based hydrocarbon compound gas of (B), (C) and (D).

On the other hand, the insulating film according to the present invention has the chemical formula (A): (Where R1 and R2 are any of CH ₃ , C ₂ H ₃ , C ₂ H ₅ , C ₃ H ₇ , C ₆ H ₅ , and m and n are arbitrary integers). It is formed on a substrate by plasma polymerization using a material gas containing a silicon-based hydrocarbon compound to be produced by a plasma CVD apparatus.

The insulating film according to the present invention has a chemical formula
(B): (Where R1, R2 and R3 are any of CH ₃ , C ₂ H ₃ , C ₂ H ₅ , C ₃ H ₇ , C ₆ H ₅ , and n is an arbitrary integer). It is formed on a substrate by plasma polymerization using a material gas containing a silicon-based hydrocarbon compound to be produced by a plasma CVD apparatus.

Further, the insulating film according to the present invention has a chemical formula
(C): (Wherein, R1, R2, R3 and R4 _{are, CH 3, C 2 H 3} , C 2 H 5, C 3 H 7, C 6 H 5
And m and n are arbitrary integers. ) Is formed on a substrate by plasma polymerization using a material gas containing a silicon-based hydrocarbon compound shown in (2) by a plasma CVD apparatus.

Further, the insulating film according to the present invention has a chemical formula
(D): (Where R1, R2, R3, R4, R5 and R6 are CH ₃ , C ₂ H ₃ , C ₂ H ₅ , C
₃ H ₇ or C ₆ H ₅ . ) Is formed on a substrate by plasma polymerization using a material gas containing a silicon-based hydrocarbon compound and an oxidizing agent of nitrogen oxide (N ₂ O) or oxygen (O ₂ ) by a plasma CVD apparatus.

Further, the insulating film according to the present invention has a chemical formula (E): (Wherein, R1, R2, R3 and R4 _{are, CH 3, C 2 H 3} , C 2 H 5, C 3 H 7, C 6 H 5
Is one of ) And nitrogen oxide (N ₂ O) or oxygen (O ₂ ) containing a silicon-based hydrocarbon compound
Is formed on a substrate by plasma polymerization using a plasma CVD apparatus using the above oxidizing agent.

On the other hand, the film forming raw material according to the present invention, which is supplied in a gaseous state near the substrate on which the film is formed and is used in a plasma CVD apparatus for forming an insulating film on the substrate by a chemical reaction, has the chemical formula (A): (Where R1 and R2 are any of CH ₃ , C ₂ H ₃ , C ₂ H ₅ , C ₃ H ₇ , C ₆ H ₅ , and m and n are arbitrary integers). It is.

The film forming raw material according to the present invention, which is supplied in a gaseous state near a substrate on which a film is formed and is used in a plasma CVD apparatus for forming an insulating film on the substrate by a chemical reaction, has a chemical formula (B): (Where R1, R2 and R3 are any of CH ₃ , C ₂ H ₃ , C ₂ H ₅ , C ₃ H ₇ , C ₆ H ₅ , and n is an arbitrary integer). It is.

Further, a film forming raw material according to the present invention, which is supplied in a gaseous state near a substrate on which a film is formed and is used in a plasma CVD apparatus for forming an insulating film on the substrate by a chemical reaction, has a chemical formula (C): (Wherein, R1, R2, R3 and R4 _{are, CH 3, C 2 H 3} , C 2 H 5, C 3 H 7, C 6 H 5
And m and n are arbitrary integers. ).

Further, in a plasma CVD apparatus which is supplied in a gas state together with an oxidizing agent of nitrogen oxide (N ₂ O) or oxygen (O ₂ ) in the vicinity of a substrate on which a film is formed, and forms an insulating film on the substrate by a chemical reaction. The film-forming raw material according to the present invention to be used has a chemical formula (D): (Where R1, R2, R3, R4, R5 and R6 are CH ₃ , C ₂ H ₃ , C ₂ H ₅ , C
₃ H ₇ or C ₆ H ₅ . ).

Further, a plasma CVD apparatus is supplied in the gaseous state together with an oxidizing agent of nitrogen oxide (N ₂ O) or oxygen (O ₂ ) in the vicinity of a substrate on which a film is formed, and forms an insulating film on the substrate by a chemical reaction. The film-forming raw material according to the present invention, which is used in the above, has a chemical formula (E) (Wherein, R1, R2, R3 and R4 _{are, CH 3, C 2 H 3} , C 2 H 5, C 3 H 7, C 6 H 5
Is one of ).

[0036]

[Function] Has at least one Si-O bond and no more than two
Having OC _n H _{2n + 1} bond and two or more hydrocarbon groups are Si
An insulating film having a low dielectric constant and excellent heat resistance and moisture resistance is formed by a method of vaporizing the silicon-based hydrocarbon compound by a direct vaporization method using a silicon-based hydrocarbon compound bonded to the material.

The material gas vaporized by the direct vaporization method stays in the plasma for a time necessary for forming a linear polymer. The result (Formula 2) is used as the basic structure, and n
Are grown in the gas phase. This deposits on the semiconductor substrate to form an insulating film having a continuous porous structure.

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The insulating film according to the present invention is extremely stable because it has a basic skeleton of Si—O having a high binding energy. In addition, a low dielectric constant is realized due to the continuous porous structure. Furthermore, dangling bonds on the side surfaces of the basic skeleton (-Si-O-) n are terminated by a hydrophobic hydrocarbon group, thereby achieving moisture absorption resistance. Furthermore, hydrocarbon groups and Si
Is generally stable. For example, a bond Si—CH ₃ with a methyl group or a bond Si—C ₆ H ₅ with benzene has a dissociation temperature of 500 ° C. or more. Since semiconductor production requires heat resistance of 450 ° C. or higher, very high heat resistance is realized.

[0039]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 schematically shows a plasma CVD apparatus used in the present invention. The apparatus includes a reaction gas supply device 12 and a plasma CVD device 1. The reaction gas supply device 12 comprises several lines 13, a control valve 8 disposed on the lines 13, and gas input ports 14, 15, 16. A flow controller 7 is connected to each control valve 8, and controls the material gas to a predetermined flow rate. A vaporizer 17 for directly vaporizing the liquid is connected to the line of the liquid reaction material 18. On the other hand, the plasma CVD apparatus 1 includes a reaction chamber 6, a gas inlet 5, a susceptor 3, and a heater 2. A large number of pores are provided on the bottom surface of the circular gas diffusion plate 10, from which a reaction gas is injected toward the semiconductor substrate 4. An exhaust port 11 is provided in the reaction chamber 6, and the inside of the reaction chamber 6 is evacuated by being connected to an external vacuum pump (not shown). The susceptor 3 is disposed to face the gas diffusion plate 10 in parallel, and heats and holds the semiconductor substrate 4 placed on the surface thereof through the heater 2. The gas inlet 5 is electrically insulated from the reaction chamber 6 and is connected to an external high frequency power supply 9. Here, the susceptor 3 may be connected to the high-frequency power supply 9. Thus, the gas diffusion plate 10 and the susceptor 3 function as high-frequency electrodes, and generate a plasma reaction region near the surface of the semiconductor substrate 4.

The method for forming an insulating film on a semiconductor substrate using the plasma CVD apparatus according to the present invention is based on the general formula Si _α O _β C _X H _Y (where α, β, x and y are integers) A) a step of vaporizing the silicon-based hydrocarbon compound represented by the direct vaporization method and introducing it into the reaction chamber of the plasma CVD apparatus; and a step of introducing an additive gas having a substantially reduced flow rate into the reaction chamber. Forming a dielectric film on the semiconductor substrate by a plasma polymerization reaction using a mixed gas of a silicon-based hydrocarbon compound gas and the additive gas as a reaction gas, and reducing the flow rate of the additive gas to reduce the flow rate of the additive gas. It is characterized in that the total flow rate of the reaction gas is substantially reduced.

Here, the general formula Si _α O _β C _X H _Y (where,
The silicon-based hydrocarbon compound represented by (α, β, x, y is an integer) preferably has at least one Si—O bond,
At most two OC _n H _{2n + 1} bonds and at least 2
A compound having a structure in which two hydrocarbon groups are bonded, specifically, a compound represented by the chemical formula (A): (Where R1 and R2 are any of CH ₃ , C ₂ H ₃ , C ₂ H ₅ , C ₃ H ₇ , C ₆ H ₅ , and m and n are arbitrary integers). Compound, formula (B): (Where R1, R2 and R3 are any of CH ₃ , C ₂ H ₃ , C ₂ H ₅ , C ₃ H ₇ , C ₆ H ₅ , and n is an arbitrary integer). Compound, formula (C): (Wherein, R1, R2, R3 and R4 _{are, CH 3, C 2 H 3} , C 2 H 5, C 3 H 7, C 6 H 5
And m and n are arbitrary integers. ), A chemical formula (D): (Where R1, R2, R3, R4, R5 and R6 are CH ₃ , C ₂ H ₃ , C ₂ H ₅ , C
₃ H ₇ or C ₆ H ₅ . ) And a mixture of the oxidizing agent nitric oxide (N ₂ O) or oxygen (O ₂ ), or a chemical formula (E): (Wherein, R1, R2, R3 and R4 _{are, CH 3, C 2 H 3} , C 2 H 5, C 3 H 7, C 6 H 5
Is one of ) And a mixture of the oxidizing agent nitric oxide (N ₂ O) or oxygen (O ₂ ), or any combination thereof.

The above-mentioned additional gas is specifically an argon gas and / or a helium gas. Argon gas is mainly used for plasma stabilization. Helium gas is used to improve plasma uniformity and film thickness uniformity.

The direct vaporization method is a method in which a liquid material whose flow rate is controlled is instantaneously vaporized in a preheated vaporization section. The difference from the bubbling method is that a carrier gas such as argon is not required. Is that a predetermined flow rate of the material gas can be obtained. Therefore, it is possible to greatly reduce the large amount of argon gas or helium gas required conventionally, and as a result, the total flow rate of the reaction gas is reduced, and the time for the material gas to stay in the plasma can be extended. it can. As a result, a sufficient polymerization reaction takes place in the gas phase, a linear polymer is formed, and a film having a continuous porous structure can be produced.

When an inert gas is input to the gas input port 14, the liquid reactant 18
Is sent to the control valve 8 through the line 13. The control valve 8 controls the flow rate of the liquid reaction material 18 to a predetermined flow rate through the flow rate controller 7. The silicon-based hydrocarbon compound 18 whose flow rate is controlled is sent to a vaporizer 17 and is vaporized by a direct vaporization method. When using an additive gas, the additive gas is introduced from the input ports 15 and 16 and the flow rate is controlled through the control valve 8. When two or more types of additive gas are used, additional input ports and valves similar to the input ports 15 and 16 are added to control the additional gas. The vaporized silicon-based hydrocarbon compound gas and / or additive gas is plasma
The gas is introduced into the gas inlet 5 of the CVD device 1. A high-frequency RF voltage of 13.4 MHz and 430 kHz is preferably applied to a space between the gas diffusion plate 10 and the semiconductor substrate 4 inside the evacuated reaction chamber 1 to form a plasma region. The semiconductor substrate 4 is heated and maintained at a temperature of preferably 350 to 450 ° C. through the susceptor 3. The reaction gas introduced from the pores of the gas diffusion plate 10 stays in the plasma region near the surface of the semiconductor substrate 4 for a predetermined time. If the residence time is short, the linear polymer will not grow sufficiently. As a result, the film deposited on the substrate does not have a continuous porous structure. Since the residence time is inversely proportional to the flow rate of the reaction gas, the residence time can be extended by reducing the flow rate of the reaction gas. This application focuses on this point,
By reducing the flow rate of the additive gas, the total flow rate of the reaction gas was significantly reduced. As a result, the linear polymer grows sufficiently and an insulating film having a continuous porous structure is formed.

To adjust the reaction in the gas phase, it is effective to add a small amount of an inert gas, a reducing gas, or an oxidizing gas.

The inert gases helium (He) and argon (A
r) is the respective ionization energy (1st ionization
energy) is 24.56 (eV) and 15.76 (eV), and therefore, the reaction in the gas phase of the material gas can be controlled by adjusting the addition amount of one or both of them.

As a method for adjusting the film quality, addition of an oxidizing gas or a reducing gas is effective. Whether to use an oxidizing gas or a reducing gas, or not to use both, depends on the ratio of oxygen contained in the material gas used as the reaction gas. The composition ratio of Si and O in the material gas molecules is as follows: In the case of the chemical formula (A): Si: O = 1: 2 In the case of the chemical formula (B): Si: O = 1: 1 In the case of the chemical formula (C): Si: O = 2: 3 In the case of chemical formula (D): Si: O = 2: 1 In the case of chemical formula (E): Si: O = 1: 0, which differs depending on the selected gas type. These source gas molecules polymerize in the gas phase to form oligomers. The composition ratio of this oligomer is ideally about Si: O = 1: 1. However, the polymerization of the oligomer proceeds further at the stage of film formation on the substrate, and the ratio of oxygen becomes higher in the film state. This composition ratio varies depending on the relative dielectric constant of the film to be formed or other film quality, but in Example 5 shown below, Si: O
= 2: 3.

The oxygen of the material gas molecules not taken into the film is desorbed and floats in the plasma. Therefore, when the ratio of oxygen contained in the material gas molecules is higher than the ratio of oxygen contained in the film after film formation, the amount of oxygen floating in the plasma increases. When the amount of oxygen in the plasma increases, the organic groups necessary for film formation are oxidized by being directly bonded to silicon (Si) atoms of the material gas, and as a result, the film quality may be deteriorated. By adding hydrogen (H ₂ ) or methane (CH ₄ ) as a reducing gas, the oxygen partial pressure in the plasma is reduced, and the oxidation of organic groups can be prevented.
When the ratio of oxygen is low, it is necessary to supply oxygen necessary for film formation by adding an oxidizing gas.

FT-IR (Fourier transform infrared spectrophotometer) spectrum measurement value or XPS of the formed film
(X-ray photoelectron spectroscopy) to measure the composition ratio, relative permittivity, and stability of Si: O, and determine whether to use an oxidizing gas or a reducing gas, or not at all based on the measured values. By determining the amount and, if used, adjusting the amount of addition appropriately, it is possible to obtain an appropriate film quality.

[0050]

EXAMPLES P-TMOS (finyltrimethoxysilane) (chemical formula 1), PM-DMOS (phenylmethyldimethoxysilane) (chemical formula 3) and DM-DMOS (dimethyldimethoxysilane) (chemical formula 4) were used as material gases. The experimental results used will be described.

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The experimental apparatus was a normal plasma CVD apparatus (Eagle-
10) was used. The film forming conditions are as follows. Additive _{gas: Ar, He, H 2,} CH 4 RF Power: 250 W (using by combining the 13.4MHz and 430 kHz) substrate temperature: 400 ° C. Reaction pressure: 7 Torr vaporization method: direct vaporization method Incidentally, the residence time Rt next Is defined as

(Equation 1)

Here, Pr is the reaction chamber pressure (Pa), Ps is the standard pressure (Pa), Tr is the average temperature of the reaction gas (K), and Ts is the standard temperature.
(K), radius (m) of the rw silicon substrate, d represents the distance (m) between the silicon substrate and the upper electrode, and F represents the total flow rate (sccm) of the reaction gas. In the experiment, the above parameters were fixed at the following values, and the relationship between the flow rate and the relative permittivity was examined by changing the flow rate F. Pr = 9.33 x 10 ² (Pa) Ps = 1.01 x 10 ⁵ (Pa) Tr = 273 + 400 = 673 (K) Ts = 273 (K) rw = 0.1 (m) d = 0.014 (m) Compare Table 1 9 is a summary of experimental results of Examples and Examples.

[Table 1]

Comparative Example 1 Material gas: P-TMOS (100 sccm) Additive gas: Ar (1000 sccm), He (1000 sccm) Total flow rate of reaction gas: 2100 sccm Other film forming conditions and equipment used are as described above. . As a result of the calculation, the residence time is Rt = 24 msec. The relative dielectric constant of the insulating film manufactured under the above conditions was ε = 3.38.

Comparative Example 2 Material gas: P-TMOS (100 sccm) Additive gas: Ar (10 sccm), He (10 sccm) Total flow rate of reaction gas: 120 sccm Other film forming conditions and equipment used are as described above. . As a result of the calculation, the residence time is Rt = 412 msec. The relative dielectric constant of the insulating film manufactured under the above conditions was ε = 3.42.

Comparative Example 3 Material gas: PM-DMOS (100 sccm) Additive gas: Ar (775 sccm), He (775 sccm) Total flow rate of reaction gas: 1650 sccm Other film forming conditions and equipment used are as described above. . As a result of the calculation, the residence time is Rt = 30 msec. The relative dielectric constant of the insulating film manufactured under the above conditions was ε = 3.41.

Comparative Example 4 Material gas: PM-DMOS (100 sccm) Additive gas: Ar (550 sccm), He (550 sccm) Total flow rate of reaction gas: 1200 sccm Other film forming conditions and equipment used are as described above. . As a result of the calculation, the residence time is Rt = 41 msec. The relative dielectric constant of the insulating film manufactured under the above conditions was ε = 3.41.

Comparative Example 5 Material gas: PM-DMOS (100 sccm) Additive gas: Ar (430 sccm), He (430 sccm) Total flow rate of reaction gas: 960 sccm Other film formation conditions and equipment used are as described above. . As a result of the calculation, the residence time is Rt = 51 msec. The relative dielectric constant of the insulating film manufactured under the above conditions was ε = 3.40.

Comparative Example 6 Material gas: PM-DMOS (100 sccm) Additive gas: Ar (310 sccm), He (310 sccm) Total flow rate of reaction gas: 720 sccm Other film forming conditions and equipment used are as described above. . As a result of the calculation, the residence time is Rt = 68 msec. The relative dielectric constant of the insulating film manufactured under the above conditions was ε = 3.35.

Example 1 Material gas: PM-DMOS (100 sccm) Additive gas: Ar (140 sccm), He (140 sccm) Total flow rate of reaction gas: 480 sccm Other film forming conditions and equipment used are as described above. . As a result of the calculation, the residence time is Rt = 103 msec. The relative dielectric constant of the insulating film manufactured under the above conditions was ε = 3.10.

Example 2 Material gas: PM-DMOS (100 sccm) Additive gas: Ar (100 sccm), He (100 sccm) Total flow rate of reaction gas: 300 sccm Other film forming conditions and equipment used are as described above. . As a result of the calculation, the residence time is Rt = 165 msec. The relative dielectric constant of the insulating film manufactured under the above conditions was ε = 2.76.

Example 3 Material gas: PM-DMOS (100 sccm) Additive gas: Ar (70 sccm), He (70 sccm) Total flow rate of reaction gas: 240 sccm Other film forming conditions and equipment used are as described above. . As a result of the calculation, the residence time is Rt = 206 msec. The relative dielectric constant of the insulating film manufactured under the above conditions was ε = 2.64.

Example 4 Material gas: PM-DMOS (100 sccm) Additive gas: Ar (10 sccm), He (10 sccm) Total flow rate of reaction gas: 120 sccm Other film forming conditions and equipment used are as described above. . As a result of the calculation, the residence time is Rt = 412 msec. The relative dielectric constant of the insulating film manufactured under the above conditions was ε = 2.45.

The following is an embodiment using DM-DMOS as a material gas.

Example 5 Material gas: DM-DMOS (100 sccm) Additive gas: Ar (10 sccm), He (10 sccm) Total flow rate of reaction gas: 120 sccm Other film forming conditions and equipment used are as described above. . As a result of the calculation, the residence time is Rt = 412 msec. The relative dielectric constant of the insulating film manufactured under the above conditions was ε = 2.58.

Example 6 Material gas: DM-DMOS (25 sccm) Additive gas: Ar (3 sccm) Total flow rate of reaction gas: 28 sccm Other film forming conditions and equipment used are as described above. As a result of the calculation, the residence time is Rt = 1764 msec. The relative dielectric constant of the insulating film manufactured under the above conditions was ε = 2.51.

Example 7 Material gas: DM-DMOS (25 sccm) Additive gas: He (5 sccm) Total flow rate of reaction gas: 30 sccm Other film forming conditions and equipment used are as described above. As a result of the calculation, the residence time is Rt = 1647 msec. The relative dielectric constant of the insulating film manufactured under the above conditions was ε = 2.50.

Example 8 Material gas: DM-DMOS (100 sccm) Additive gas: H ₂ (20 sccm) Total flow rate of reaction gas: 120 sccm Other film forming conditions and equipment used are as described above. As a result of the calculation, the residence time is Rt = 412 msec. The relative permittivity of the insulating film manufactured under the above conditions was ε = 2.52.

Example 9 Material gas: DM-DMOS (25 sccm) Additive gas: H ₂ (5 sccm) Total flow rate of reaction gas: 30 sccm Other film forming conditions and equipment used are as described above. As a result of the calculation, the residence time is Rt = 1647 msec. The relative dielectric constant of the insulating film manufactured under the above conditions was ε = 2.49.

Example 10 Material gas: DM-DMOS (25 sccm) Additive gas: CH ₄ (5 sccm) Total flow rate of reaction gas: 30 sccm Other film forming conditions and equipment used are as described above. As a result of the calculation, the residence time is Rt = 1647 msec. The relative dielectric constant of the insulating film manufactured under the above conditions was ε = 2.67.

Embodiment 11 The film forming conditions are different from those of the above embodiment as follows. Additive gas: He (5 sccm) RF power: 400 W (27 MHz only) Substrate temperature: 400 ° C Reaction pressure: 3 Torr Vaporization method: Direct vaporization Material gas: DM-DMOS (25 sccm) Total flow rate of reaction gas: 30 sccm Other film forming conditions and equipment used are as described above. As a result of the calculation, the residence time is Rt = 706 msec. The relative dielectric constant of the insulating film manufactured under the above conditions was ε = 2.58.

The above experimental results will be discussed below with reference to FIGS. FIG. 2 is a graph showing the relationship between the total flow rate of the reaction gas and the relative permittivity for PM-DMOS, and FIG. 3 is a graph showing the relationship between the residence time and the relative permittivity for PM-DMOS.

First, the relationship between the gas flow rate and the relative permittivity of PM-DMOS will be discussed. It can be seen from the graph of FIG. 2 that the relative dielectric constant is almost constant at ε = 3.4 up to a flow rate of about 700 sccm. However, when the flow rate drops below 700 sccm, the relative dielectric constant starts to decrease, and when the flow rate drops below 500 sccm, the residence time sharply increases and the relative dielectric constant sharply decreases. From the graph of FIG. 3, it can be seen that the relative permittivity sharply decreases around the time when the residence time Rt exceeds 70 msec. Rt> 400 msec, relative permittivity ε = 2.45
An extremely low dielectric constant insulating film was realized.

Therefore, from the above experimental results, when PM-DMOS is used as the material gas, the residence time is set to Rt> 100.
It was found that the relative dielectric constant of the insulating film can be controlled to ε <3.1 by controlling to msec.

Next, it will be examined whether or not this experimental result holds for P-TMOS. Comparative Example 1 and Comparative Example 2 are both experimental results using P-TMOS as a material gas. It can be seen that the relative permittivity does not decrease even if the total flow rate of the reaction gas is greatly reduced to 5.7%. Therefore,
It can be seen that the relationship between the flow rate and the relative permittivity established in PM-DMOS or the relationship between the residence time and the relative permittivity is not established in P-TMOS.

Here, looking at Examples 5 to 10 in which DM-DMOS is used as a material gas, the relative dielectric constant of the insulating film is ε.
<2.7, which indicates that the control is very small. PM-DMOS and DM-DMOS are common in having the structure of the chemical formula (A). PM-DMOS has C ₆ H ₅ and CH ₃ at R1 and R2 of formula (A), respectively, while DM-DMOS has R 6 of formula (A)
1 and R2 have CH ₃ and CH ₃ respectively. This indicates that the material gas having the structure of the chemical formula (A) generally has a low relative dielectric constant.

The difference in the relative permittivity depending on the type of the material gas will be examined. A comparison between Comparative Example 2 and Examples 4 and 5 shows that although the flow rate and other film forming conditions are completely the same,
It can be seen that the relative permittivity of P-TMOS is ε = 3.42, the relative permittivity of PM-DMOS is ε = 2.45, and the relative permittivity of DM-DMOS is ε = 2.58. This is presumed to be due to the difference in the molecular structure of the material gas. PM-DMOS and DM-DMOS
Has two relatively unstable O-CH ₃ bonds, but these bonds are broken and a polymerization reaction occurs to form a linear polymer (Formula 5) in the gas phase.

Embedded image

Then, the polymer is deposited on the semiconductor substrate to form a film having a continuous porous structure, and the dielectric constant of the film decreases.
On the other hand, since P-TMOS has _three O-CH ₃ bonds, the polymer formed in the gas phase does not grow linearly even if the residence time is extended. Therefore, the deposited film does not have a continuous porous structure, and the dielectric constant of the film does not decrease.

Therefore, from the above experimental results, the silicon-based hydrocarbon compound used as the material gas has not only Si—O bonds but also two or less OC _n H _{2n + 1} bonds and at least 2 One in which two hydrocarbon groups are bonded has been found to be suitable.

Further, with respect to Examples 4 and 5, the following 2
Two experiments were performed to verify the performance of both thin films.

[Experiment (I)] PCT test Experimental conditions; Experimental equipment: Pressure Cooker Material gases: PM-DMOS (Example 4), DM-DMOS (Example 5) Film thickness: 1 μm Temperature: 120 ° C. Humidity: 100 % Leaving time: 1 hour (Experimental results) Material gas Dielectric constant ε immediately after film formation Dielectric constant ε 'after standing PM-DMOS (Example 4) 2.45 2.45 DM-DMOS (Example 5) 2.58 2.58 The above experiment From the results, the relative dielectric constant ε immediately after film formation and the temperature of 120
The relative dielectric constant ε ′ after the PCT test left for 1 hour in an environment of 100 ° C. and 100% humidity did not change, indicating that both insulating films were extremely stable.

[Experiment (II)] TDS: Thermal desorption test Experimental conditions; Material gases: PM-DMOS (Example 4), DM-DMOS (Example 5) Temperature: Temperature increased at 10 ° C./min. vacuum measuring method: measured (experimental results) the amount of molecules desorbed 4 temperature and methane (CH ₄₎ thermal desorption spectrum of molecular weight 16 due to gas desorption (thermal Desorpt
It shows the relationship with (Ion spectra). From this graph, it can be seen that PM-DMOS (Example 4) starts desorption at around 450 ° C., peaks at around 800 ° C., and ends at around 960 ° C. On the other hand, DM-DMOS (Example 5)
It can be seen that desorption starts at around 00 ° C, peaks at around 820 ° C, and ends at around 1000 ° C.

FIG. 5 shows the relationship between the temperature and the increase in pressure caused by the total number of all kinds of molecules desorbed from the insulating film. From this graph, it can be seen that PM-DMOS (Example 4) begins to desorb at around 500 ° C., peaks at around 820 ° C., and then sharply decreases. On the other hand, it can be seen that the DM-DMOS (Example 5) starts desorption at around 500 ° C., reaches a peak at around 840 ° C., and sharply decreases thereafter.

From the results shown in FIGS. 4 and 5, no desorption of gas occurs at 450 ° C. or less for PM-DMOS (Example 4), and no gas desorption at 500 ° C. or less for DM-DMOS (Example 5). Since no desorption occurred, it was found that the heat-resistant temperature of 400 to 450 ° C required for the low-k film was cleared in all cases.
Moreover, it was found that DM-DMOS has a high heat resistance of 500 ° C.

[0084]

According to the method for producing an insulating film according to the present invention using the silicon-based hydrocarbon compound as a material gas according to the present invention, it is possible to produce a low-dielectric-constant film having high heat resistance and moisture absorption resistance. It became.

Further, the dielectric constant of the film can be easily controlled by controlling the residence time of the reaction gas by the method of manufacturing an insulating film according to the present invention.

Further, according to the method for manufacturing an insulating film according to the present invention, it is possible to manufacture an insulating film having a low dielectric constant which is extremely stable and has high heat resistance.

Further, according to the method of manufacturing an insulating film according to the present invention, an insulating film having a low dielectric constant can be easily manufactured without increasing the apparatus cost.

[Brief description of the drawings]

FIG. 1 schematically shows a plasma CVD apparatus used for manufacturing an insulating film according to the present invention.

FIG. 2 is a graph showing a relationship between a total flow rate of a reaction gas and a relative permittivity in an experiment using PM-DMOS as a material gas.

FIG. 3 is a graph showing the relationship between residence time and relative permittivity in an experiment using PM-DMOS as a material gas.

FIG. 4 shows a PM-DMOS film and a D-film formed according to the present invention.
₄ is a graph showing the relationship between the temperature and the desorption of CH ₄ in the M-DMOS film.

FIG. 5 shows a PM-DMOS film and a D-DMOS film formed according to the present invention.
5 is a graph showing the relationship between the temperature of the M-DMOS film and the increase in pressure caused by all desorbed molecules.

[Explanation of symbols]

 1 Plasma CVD device 2 Heater 3 Susceptor 4 Semiconductor substrate 5 Gas inlet 6 Reaction chamber 7 Flow control device 8 Control valve 9 High frequency power supply 10 Gas diffusion plate 11 Exhaust port 12 Reactive gas supply device 13 Line 14 Gas input port 15 Gas input port 16 Gas input port 17 Vaporizer 18 Liquid reaction material

Claims (21)

[Claims] 1. A method for forming an insulating film having a low dielectric constant on a semiconductor substrate using a plasma CVD apparatus, comprising the general formula: Si _α O _β C _X H _Y (where α, β, x , y is an integer) by vaporizing a silicon-based hydrocarbon compound represented by the direct vaporization method and introducing it into the reaction chamber of the plasma CVD apparatus, and introducing an additive gas having a substantially reduced flow rate into the reaction chamber. And a step of forming an insulating film on the semiconductor substrate by a plasma polymerization reaction using a mixed gas of the silicon-based hydrocarbon compound gas and the additive gas as a reaction gas, and reducing a flow rate of the additive gas. Wherein the total flow rate of the reaction gas is substantially reduced. 2. The method according to claim 1, wherein the silicon-based hydrocarbon compound has a chemical formula: (Where R1 and R2 are any of CH ₃ , C ₂ H ₃ , C ₂ H ₅ , C ₃ H ₇ , C ₆ H ₅ , and m and n are arbitrary integers). The method comprises at least one compound of the formula: 3. The method according to claim 1, wherein the silicon-based hydrocarbon compound has a chemical formula: (Where R1, R2 and R3 are any of CH ₃ , C ₂ H ₃ , C ₂ H ₅ , C ₃ H ₇ , C ₆ H ₅ , and n is an arbitrary integer). The method comprises at least one compound of the formula: 4. The method according to claim 1, wherein the silicon-based hydrocarbon compound has a chemical formula: (Wherein, R1, R2, R3 and R4 _{are, CH 3, C 2 H 3} , C 2 H 5, C 3 H 7, C 6 H 5
And m and n are arbitrary integers. ) Comprising at least one compound represented by the formula: 5. The method according to claim 1, wherein the silicon-based hydrocarbon compound has a chemical formula: (Where R1, R2, R3, R4, R5 and R6 are CH ₃ , C ₂ H ₃ , C ₂ H ₅ , C
₃ H ₇ or C ₆ H ₅ . ), And the additive gas is nitrogen oxide (N ₂ O) or oxygen (O ₂ ), argon (Ar) gas and / or helium (H).
e) The method where it is a gas. 6. The method according to claim 3, wherein the material gas further comprises at least one silicon-based hydrocarbon compound according to claim 2 or 4. 7. The method according to claim 1, wherein the additive gas is an argon (Ar) gas and / or a helium (He) gas. 8. The method according to claim 1, wherein the additive gas is a hydrogen (H ₂ ) gas and / or a methane (CH ₄ ) gas. 9. The method according to claim 1, wherein said additional gas is hydrogen (H ₂ ) gas and / or methane (CH ₄ ) gas and argon (Ar) gas and / or A method using a mixture of helium (He) gas. 10. The method according to claim 1, wherein the silicon-based hydrocarbon compound has a chemical formula: (Wherein, R1, R2, R3 and R4 _{are, CH 3, C 2 H 3} , C 2 H 5, C 3 H 7, C 6 H 5
Is one of At least one compound of the formula
And the additive gas is nitrogen oxide (N ₂ O) or oxygen
(O ₂ ), argon (Ar) and / or helium (He),
Where way. 11. The method according to claim 10, further comprising at least one silicon-based hydrocarbon compound gas according to claim 2 as a material gas. 12. The chemical formula: (Where R1 and R2 are any of CH ₃ , C ₂ H ₃ , C ₂ H ₅ , C ₃ H ₇ , C ₆ H ₅ , and m and n are arbitrary integers). An insulating film formed on a substrate by plasma polymerization using a material gas containing a silicon-based hydrocarbon compound by a plasma CVD apparatus. 13. The chemical formula: (Where R1, R2 and R3 are any of CH ₃ , C ₂ H ₃ , C ₂ H ₅ , C ₃ H ₇ , C ₆ H ₅ , and n is an arbitrary integer). An insulating film formed on a substrate by plasma polymerization using a material gas containing a silicon-based hydrocarbon compound by a plasma CVD apparatus. 14. The chemical formula: (Wherein, R1, R2, R3 and R4 _{are, CH 3, C 2 H 3} , C 2 H 5, C 3 H 7, C 6 H 5
And m and n are arbitrary integers. (2) An insulating film formed on a substrate by plasma polymerization using a material gas containing a silicon-based hydrocarbon compound by a plasma CVD apparatus. 15. The chemical formula: (Where R1, R2, R3, R4, R5 and R6 are CH ₃ , C ₂ H ₃ , C ₂ H ₅ , C
₃ H ₇ or C ₆ H ₅ . An insulating film formed on a substrate by plasma polymerization using a plasma CVD apparatus using a material gas containing a silicon-based hydrocarbon compound and a oxidizing agent of nitrogen oxide (N ₂ O) or oxygen (O ₂ ) . 16. The chemical formula: (Wherein, R1, R2, R3 and R4 _{are, CH 3, C 2 H 3} , C 2 H 5, C 3 H 7, C 6 H 5
Is one of ) And nitrogen oxide (N ₂ O) or oxygen (O ₂ ) containing a silicon-based hydrocarbon compound
An insulating film formed on a substrate by plasma polymerization using a plasma CVD apparatus using the above oxidizing agent. 17. A plasma CVD apparatus which is supplied in a gaseous state in the vicinity of a substrate on which a film is formed and which is used to form an insulating film on the substrate by a chemical reaction. (Where R1 and R2 are any of CH ₃ , C ₂ H ₃ , C ₂ H ₅ , C ₃ H ₇ , C ₆ H ₅ , and m and n are arbitrary integers). Raw materials for film formation. 18. A plasma CVD apparatus which is supplied in a gaseous state near a substrate on which a film is to be formed and which is used to form an insulating film on the substrate by a chemical reaction. (Where R1, R2 and R3 are any of CH ₃ , C ₂ H ₃ , C ₂ H ₅ , C ₃ H ₇ , C ₆ H ₅ , and n is an arbitrary integer). Raw materials for film formation. 19. A chemical CVD apparatus which is supplied in a gaseous state near a substrate on which a film is formed and which is used in a plasma CVD apparatus for forming an insulating film on the substrate by a chemical reaction. (Wherein, R1, R2, R3 and R4 _{are, CH 3, C 2 H 3} , C 2 H 5, C 3 H 7, C 6 H 5
And m and n are arbitrary integers. ). 20. A gaseous state is supplied to the vicinity of a substrate on which a film is formed, together with an oxidizing agent of nitrogen oxide (N ₂ O) or oxygen (O ₂ );
Plasma CV that forms an insulating film on a substrate by chemical reaction
Chemical formula used in D apparatus: (Where R1, R2, R3, R4, R5 and R6 are CH ₃ , C ₂ H ₃ , C ₂ H ₅ , C
₃ H ₇ or C ₆ H ₅ . ). 21. A gaseous state is supplied to the vicinity of a substrate on which a film is formed, together with an oxidizing agent of nitrogen oxide (N ₂ O) or oxygen (O ₂ ),
Plasma CV that forms an insulating film on a substrate by chemical reaction
Chemical formula used in D apparatus: (Wherein, R1, R2, R3 and R4 _{are, CH 3, C 2 H 3} , C 2 H 5, C 3 H 7, C 6 H 5
Is one of ).