JP3401993B2 - Interlayer insulating film and method of forming interlayer insulating film - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insulating material, an interlayer insulating film of a semiconductor element made of the insulating material, and a method for forming the same.

[0002]

2. Description of the Related Art In recent years, in the field of semiconductor manufacturing, with the miniaturization of devices, ILD (Inter Layer Dielectric
ric; inter-layer insulation film) has a high dielectric constant, which causes problems such as increase in capacitance between wirings and signal propagation delay of wirings.
A commonly used interlayer insulating film, for example, BPSG (boron-phosphosilicate glass), NSG (non-doped tosilicate glass), P-TEOS (plasma-).
Insulating films such as tetraethoxysilane), O ₃ -TEOS (ozone-tetraethoxysilane), and SOG (spin-on glass) usually have a relative dielectric constant (ε) of 4 or more. It is effective to lower the dielectric constant of.

Therefore, recently, in order to lower the dielectric constant of the interlayer insulating film, an oxide film (SiO 2) into which fluorine atoms are introduced is used.
It has been proposed to form an interlayer insulating film in F). Further, since an organic compound material can have a relatively low dielectric constant, it has been proposed to form the interlayer insulating film by a vapor deposition film of polyparaxylylene or a film obtained by introducing fluorine atoms into polyimide. When the former SiOF film is used, the relative dielectric constant of the interlayer insulating film can be made lower than that of the conventional one, but the relative dielectric constant is usually about 3, whereas when the latter organic compound material is used, it is 2 Attention has been paid because a relative dielectric constant of about 3 can be achieved.

[0004]

However, when an organic compound is used as the material of the interlayer insulating film, the heat resistance of the organic compound is low, and therefore, for example, a film of polyparaxylylene or the like has a temperature of about 200 to 300 ° C. At best 5 with a polyimide film
Since it cannot withstand a temperature of about 00 ° C., it limits the subsequent manufacturing process of the semiconductor element. Therefore, development of an interlayer insulating film having excellent heat resistance and a low dielectric constant has been earnestly desired.

[0005]

The insulating material of the present invention is a silicon phthalocyanine in which at least one hydrogen bonded to an aromatic ring in a molecule is substituted with a fluorine atom, and an insulating ring bonded to an aromatic ring in a molecule. A metal-free phthalocyanine in which at least one of the hydrogen atoms is substituted with a fluorine atom, a silicon naphthalocyanine in which at least one of the hydrogen atoms bonded to an aromatic ring in the molecule is substituted with a fluorine atom, and an aromatic ring in the molecule The main component is at least one of metal-free naphthalocyanines in which at least one of the bonded hydrogen atoms is replaced by a fluorine atom.

Since the phthalocyanine derivative and the naphthalocyanine derivative have a coordination ability, it is possible to introduce various metal atoms. However, in the insulating material of the present invention, this can also be used as a material for an interlayer insulating film of a semiconductor element. Preferably, that is, metal-free phthalocyanine or metal-free naphthalocyanine in which metal atoms are not coordinated so as to prevent metal contamination of a semiconductor device, or silicon phthalocyanine in which silicon atoms are coordinated so as not to affect metal contamination are preferred. Alternatively, it is mainly composed of silicon naphthalocyanine.

Silicon phthalocyanine or metal-free phthalocyanine having no fluorine atom introduced has four aromatic rings, that is, four benzene rings, in one molecule and four hydrogen atoms are bonded to each benzene ring. It is a thing. Therefore, for example, all of the hydrogens bonded to each benzene ring are each replaced with a fluorine atom (hereinafter,
Silicon phthalocyanine or metal-free phthalocyanine is referred to as completely fluorine-substituted).
Six fluorine atoms are bonded. Further, silicon naphthalocyanine or metal-free naphthalocyanine having no fluorine atom introduced has four aromatic rings in one molecule,
That is, there are four naphthalene rings and six hydrogens are bonded to each of these naphthalene rings. Therefore, for example, silicon naphthalocyanine or metal-free naphthalocyanine in which all of the hydrogens bonded to each naphthalene ring are each substituted with a fluorine atom (hereinafter referred to as complete fluorine substitution) is a total of 24 naphthalene rings in the molecule. The fluorine atom of is bonded.

The silicon phthalocyanine, the metal-free phthalocyanine benzene ring, the silicon naphthalocyanine, and the metal-free naphthalocyanine naphthalene ring of the present invention have 1
And a substituent such as an alkoxy group or an alkyl group may be bonded. Such an insulating material is suitable as an insulating material for an insulating film in a printed wiring board, etc., in addition to the interlayer insulating film in the semiconductor element described above. The interlayer insulating film according to the present invention is an interlayer insulating film formed on a semiconductor element, and is formed by using the above-mentioned insulating material of the present invention. For example, it is composed of a plasma polymerized film formed by polymerizing the above insulating material in plasma.

The method of forming an interlayer insulating film according to the present invention is a method of forming an interlayer insulating film on the surface of a substrate by using the above-mentioned insulating material of the present invention. Particularly, an interlayer insulating film made of a plasma polymerized film is formed. Is the way to do it. That is, after arranging the substrate in the container in advance, an atmosphere consisting of the evaporation material of the above-mentioned insulating material is formed in the container, plasma is generated in the container, and the evaporation material is polymerized in the plasma while the surface of the substrate surface is being formed. Then, an interlayer insulating film made of the above insulating material is formed.

Examples of the substrate in the present invention include a substrate made of silicon or the like, a wiring layer formed on the substrate, and the like. Further, the present invention can be carried out by using an ordinary plasma polymerization apparatus such as a parallel plate type plasma polymerization apparatus and an ECR plasma polymerization apparatus.

For example, when an interlayer insulating film is formed on the surface of a substrate by using a parallel plate type plasma polymerization apparatus, a crucible in which the substrate and the above insulating material are arranged in advance in a vacuum chamber as a container of the present invention. And are installed facing each other.
A shutter is placed between the substrate and the crucible. Next, the inside of the vacuum chamber is evacuated by a negative pressure source such as a cryopump, and the crucible is heated by a method such as resistance heating. Along with this, a small amount of an inert gas such as argon (Ar) or nitrogen (N ₂ ) is introduced into the vacuum chamber, and high frequency is applied to the vacuum chamber to discharge the gas. Inert plasma is generated.

When the evaporation of the insulating material into the vacuum chamber starts by heating the crucible (usually, the pressure in the vacuum chamber is 0.133 × 10 ⁻² to 0.133 × 10 ^−3).
At 200 ° C or higher at Pa), open the shutter. As a result, the vaporized material is deposited on the surface of the substrate while being polymerized in plasma, and an interlayer insulating film made of the above insulating material is formed on the surface of the substrate. In this method, the start of evaporation can be monitored by starting the evaporation by increasing the pressure value of the pressure gauge attached to the vacuum chamber.

In this method, when the main component of the insulating material is the above-mentioned silicon phthalocyanine or metal-free phthalocyanine of the present invention, when plasma polymerization is performed, one molecule of carbon of each benzene ring of silicon phthalocyanine and metal-free phthalocyanine is obtained. And other silicon phthalocyanines,
It is considered that the interlayer insulating film having a structure in which the carbon of the benzene ring of the metal-free phthalocyanine is bonded, that is, the structure in which the matrix is three-dimensionally expanded is formed. Similarly, when the main component of the insulating material is the above-described silicon naphthalocyanine of the present invention or metal-free naphthalocyanine,
When the plasma polymerization is performed, one molecule of silicon naphthalocyanine or carbon of each naphthalene ring of metal-free naphthalocyanine is bonded to carbon of another silicon naphthalocyanine or naphthalene ring of metal-free naphthalocyanine, that is, three-dimensional It is considered that an interlayer insulating film having a structure in which the matrix is expanded is formed.

[0014]

[Function] Generally, it is known that the phthalocyanine derivative and the naphthalocyanine derivative are thermally stable compounds. Since the insulating material of the present invention contains such a phthalocyanine derivative or naphthalocyanine derivative as a main component, it becomes a highly heat resistant organic insulating material. Further, it is generally known that the refractive index of an insulating material decreases when fluorine atoms are introduced, and that the dielectric constant decreases when the refractive index decreases. The insulating material of the present invention is mainly composed of silicon phthalocyanine, metal-free phthalocyanine, silicon naphthalocyanine, and metal-free naphthalocyanine in which at least one hydrogen bonded to an aromatic ring in the molecule is substituted with a fluorine atom. Therefore, the refractive index is lower than that of one not substituted with a fluorine atom, and as a result, the dielectric constant is low.

Since the interlayer insulating film of the present invention is made of the above insulating material, it is an organic insulating material having high heat resistance. Therefore, if this interlayer insulating film is used, there is no restriction on the manufacturing process of the semiconductor element after the formation of the interlayer insulating film. Further, since the interlayer insulating film of the present invention has a low dielectric constant because it is made of the above insulating material, the capacitance between the wirings in the semiconductor element is reduced and the signal propagation delay of the wirings is prevented by using this interlayer insulating film. It

In the method for forming an interlayer insulating film according to the present invention, the interlayer insulating film having a structure in which the molecules of the above-mentioned silicon phthalocyanine, metal-free phthalocyanine, silicon naphthalocyanine and metal-free naphthalocyanine are three-dimensionally spread in a matrix. Thus, an interlayer insulating film having high heat resistance and a low dielectric constant and high strength is formed.

[0017]

EXAMPLES Examples of the present invention will be described below. Needless to say, the present invention is not limited to the examples below. (Example 1) The parallel plate type plasma polymerization apparatus described above provided with a quartz crucible that was pre-fired and thoroughly washed was prepared in advance, and the completely fluorine-substituted metal-free phthalocyanine was contained in this crucible as a 100% component. Place 5g of insulating material,
The substrate was placed in the vacuum chamber. Then, the vacuum chamber was evacuated, and the crucible was heated to evaporate the insulating material. When the heating temperature reached 200 ° C., the heating was once suppressed, the impurities contained in the evaporated material were attached to the shutter, and then the shutter was opened. In addition, the insulating material is vaporized and A
An r gas was introduced, and a high frequency of 13.56 MHz was applied to generate plasma, and an interlayer insulating film was formed on the substrate for about 10 minutes. During film formation, A
The flow rate of r gas was 50 sccm, the pressure in the vacuum chamber was 50 Pa, the frequency of the high frequency was 13.56 MHz, and the high frequency power was 30 W.

When the relative dielectric constant of the interlayer insulating film formed by this operation was measured, it was 3.0. Also DTA
The heat resistant temperature was measured by (Differential Thermal Analysis) and found to be 730 ° C. Therefore, it was confirmed that the interlayer insulating film formed as described above has higher heat resistance and lower dielectric constant than the conventional one.

(Embodiment 2) The insulating material used in Embodiment 1 is approximately 10% of fluorine-free metal-free naphthalocyanine.
An interlayer insulating film was formed in the same manner as in Example 1 except that the insulating material was changed to 0%. The relative dielectric constant of the interlayer insulating film formed by this operation was 2.7. When the heat resistant temperature was measured by the same DTA as in Example 1, it was 8
It was 20 ° C. From this result, it was confirmed that the interlayer insulating film formed as described above also has high heat resistance and a low dielectric constant.

(Example 3) Example 1 was repeated except that the insulating material in Example 1 was replaced with an insulating material composed of completely fluorine-substituted metal-free phthalocyanine and completely fluorine-substituted metal-free naphthalocyanine (weight ratio 1: 1). Similarly, an interlayer insulating film was formed. The relative dielectric constant of the interlayer insulating film formed by this operation was 2.9. Further, the heat resistant temperature was measured by the same DTA as in Example 1 and found to be 780 ° C.
Met. Therefore, it was confirmed that an interlayer insulating film having high heat resistance and a low dielectric constant was formed.

(Embodiment 4) The insulating material used in Embodiment 1 is substantially 100% fluorine-substituted silicon phthalocyanine.
The interlayer insulating film was formed in the same manner as in Example 1 except that the insulating material was changed to 100%. The relative dielectric constant of the interlayer insulating film formed by this operation was 3.1. Example 1
When the heat resistant temperature was measured by the same DTA as
It was 0 ° C. From this result, it was confirmed that the interlayer insulating film formed as described above also has high heat resistance and a low dielectric constant.

(Embodiment 5) The insulating material used in Embodiment 1 is approximately 10% of fluorine-substituted silicon naphthalocyanine.
An interlayer insulating film was formed in the same manner as in Example 1 except that the insulating material was changed to 0%. The relative dielectric constant of the interlayer insulating film formed by this operation was 2.8. When the heat resistant temperature was measured by the same DTA as in Example 1, it was 8
It was 00 ° C. Therefore, it was confirmed that an interlayer insulating film having high heat resistance and a low dielectric constant was formed.

(Example 6) An interlayer insulating film was formed in the same manner as in Example 1 except that the insulating material in Example 1 was changed to an insulating material containing 100% of completely fluorine-substituted tetramethoxy metal-free phthalocyanine. went. The relative dielectric constant of the interlayer insulating film formed by this operation was 3.1. Further, the heat resistant temperature was measured by the same DTA as in Example 1, and it was 680 ° C. Therefore, it was confirmed that the interlayer insulating film formed as described above also has high heat resistance and a low dielectric constant.

(Embodiment 7) The insulating material used in Embodiment 1 is approximately 100% of partially fluorine-substituted metal-free phthalocyanine.
The interlayer insulating film was formed in the same manner as in Example 1 except that the insulating material was changed to 100%. In addition, in this insulating material, fluorine atoms are contained in the benzene ring of metal-free phthalocyanine in an amount of 16 to
It consists of a mixture of four bonded together. The relative dielectric constant of the interlayer insulating film formed by this operation was 3.3.
Further, the heat resistant temperature was measured by the same DTA as in Example 1, and it was 630 ° C. Therefore, it was confirmed that the interlayer insulating film formed as described above also has high heat resistance and a low dielectric constant.

[0025]

INDUSTRIAL APPLICABILITY As described above, the insulating material of the present invention has a thermally stable phthalocyanine derivative and naphthalocyanine derivative as a main component, and a fluorine atom is introduced into this main component. It becomes an organic insulating material having properties and a low dielectric constant. Since the interlayer insulating film of the present invention is made of the above-mentioned insulating material and has high heat resistance, the use of this interlayer insulating film allows the semiconductor element to be manufactured without limiting the manufacturing process after the formation of the interlayer insulating film. You can Since the interlayer insulating film of the present invention is made of the above insulating material and has a low dielectric constant, the use of this interlayer insulating can reduce the capacitance between the wirings in the semiconductor element, and can improve the signal propagation speed of the wirings. It can speed up. In the method for forming an interlayer insulating film of the present invention, since the insulating material is formed by polymerizing with plasma, an interlayer insulating film having high heat resistance and low dielectric constant and high strength is formed. can do.
Therefore, by using this method, it is possible to manufacture a semiconductor element having highly reliable wiring.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI // C07D 487/22 C07D 487/22 C07F 7/10 C07F 7/10 Q (58) Fields investigated (Int.Cl. ⁷ , DB name) H01B 3/16-3/56 CA (STN) REGISTRY (STN)

Claims (2)

(57) [Claims] 1. An interlayer insulating film formed on a semiconductor device, comprising : a silicon phthalocyanine or a metal-free phthalocyanine in which at least one hydrogen bonded to an aromatic ring in the molecule is substituted with a fluorine atom; Characterized in that at least one of the hydrogens bonded to the aromatic ring is composed of an insulating material containing at least one of silicon naphthalocyanine or metal-free naphthalocyanine substituted with a fluorine atom as a main component. Insulating film. 2. A method of forming an interlayer insulating film on the surface of a substrate of a semiconductor device , wherein at least one hydrogen bonded to an aromatic ring in a molecule is fluorine after the substrate is previously placed in a container. At least one of an atom-substituted silicon phthalocyanine or a metal-free phthalocyanine and a silicon naphthalocyanine or a metal-free naphthalocyanine in which at least one hydrogen bonded to an aromatic ring in the molecule is replaced by a fluorine atom.
An atmosphere composed of an evaporation material of an insulating material containing a seed as a main component is formed in the container, plasma is generated in the container, and the evaporation material is polymerized to form an interlayer insulation film composed of the insulating material on the surface of the substrate. A method for forming an interlayer insulating film, which comprises forming a film.