JP3445902B2 - Method for manufacturing semiconductor device - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a wiring provided on a semiconductor substrate, which has moisture resistance and a relative dielectric constant of 3.
The present invention relates to a semiconductor device having an insulating thin film of 0 or less and excellent in flatness, and a manufacturing method thereof.

[0002]

2. Description of the Related Art Generally, in a semiconductor device, an insulating thin film such as SiO ₂ is formed as a surface protective film or an interlayer insulating film after forming an element and a metal wiring on a semiconductor substrate. It is preferable that such an insulating thin film affects the characteristics of the semiconductor device, has a low dielectric constant, has moisture resistance, and has excellent flatness. That is, the transmission delay time τ of the metal wiring on the semiconductor substrate is proportional to the dielectric constant of the insulating thin film provided on the metal wiring. Particularly, in a highly integrated semiconductor device, the transmission delay time τ is Since the influence on τ becomes large, it is essential to reduce the dielectric constant of the insulating thin film. Further, since the insulating thin film also functions as a protective film for circuits and metal wiring, it must also be a film having high moisture resistance. Furthermore, since the insulating thin film is also used as an interlayer insulating thin film, it needs to be a film having excellent flatness.

[0003]

Conventionally, TEOS (tetraethoxysilane) has been used to reduce the dielectric constant of insulating thin films.
In order to lower the dielectric constant of the insulating thin film by adding F, which lowers the dielectric constant of the insulating thin film, to the SiO ₂ insulating thin film formed by the plasma CVD method using Since the moisture resistance of the SiO ₂ insulating thin film is lowered, the amount of F added is actually limited to a certain degree, and as a result, the relative dielectric constant of the insulating thin film is limited to about 3.7, which is a high integration. It has been difficult to obtain a relative dielectric constant of 3.0 or less, which is required in a semiconductor device for semiconductors.

Further, as the degree of integration of semiconductor devices increases, the wiring interval between metal wirings on a semiconductor substrate becomes narrower, and it is difficult to flatly fill narrow metal wirings only with an SiO ₂ insulating thin film formed of TEOS. Therefore, as shown in FIG.
On the SiO ₂ film 4 (FIG. 3B) formed of TEOS, SOG (Spin-O) having excellent step coverage and flatness is provided.
n-Glass) 5 is formed (FIG. 3C), and Si is further formed.
A composite process such as a sandwich method for forming a laminated O ₂ film 6 (FIG. 3D) has been used. However, such a sandwich method has complicated steps, and it takes time to form an insulating thin film. SOG5 has low heat resistance, 40%
It has a defect that cracks are generated in a high temperature process of 0 ° C or higher.

It is therefore an object of the present invention to provide a semiconductor device having an insulating thin film which is moisture resistant, has a relative dielectric constant of 3.0 or less and is excellent in flatness, and a method for manufacturing the same.

[0006]

As a result of intensive studies, the inventors have formed an insulating thin film arranged on a metal wiring on a semiconductor substrate from a cyclic hydrocarbon containing F and N, particularly a polymer thereof. It was found that the above object can be achieved by the above, and the present invention was completed.

That is, the present invention is a semiconductor device including an insulating thin film formed so as to cover a metal wiring provided on a semiconductor substrate, wherein the insulating thin film is made of a cyclic hydrocarbon containing F and N. The semiconductor device is formed and has a relative dielectric constant of 3.0 or less. By forming the insulating thin film from such a cyclic hydrocarbon, the relative dielectric constant can be reduced to 3.0 or less while maintaining the moisture resistance of the insulating thin film, and the transmission delay time of the metal wiring covered by the insulating thin film This is because it is possible to obtain an insulating thin film excellent in moisture resistance and flatness while reducing τ.

The above cyclic hydrocarbon preferably further has a polymer structure. This is because when the cyclic hydrocarbon has a polymer structure, the fluidity of the cyclic hydrocarbon is improved, and an insulating thin film that is more excellent in step coverage and flatness can be obtained.

Further, according to the present invention, a step of introducing respective reaction gases of lower hydrocarbon, lower fluorocarbon, and nitrogen into a reaction chamber in which a semiconductor substrate having metal wiring provided on the semiconductor substrate is placed, and a plasma CVD method. Then, the reaction gas is reacted to deposit an insulating thin film made of a cyclic hydrocarbon containing F and N on the semiconductor substrate.

It is preferable that the method for manufacturing a semiconductor device further includes a step of polymerizing the reaction gas to deposit an insulating thin film made of a cyclic hydrocarbon polymer containing F and N on the semiconductor substrate. . This is because the insulating thin film having more excellent flatness can be obtained by including the polymerization step of the cyclic hydrocarbon.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a step of forming an insulating thin film, which is a part of a manufacturing process of a semiconductor device, according to an embodiment of the present invention. Figure 3 shows the schematic of the reaction chamber. In the present embodiment, the semiconductor substrate 13 is placed on the conductive support 12 in the reaction chamber 11 shown in FIG. The semiconductor substrate 13 is provided with a metal wiring 1 such as an Al wiring on the substrate and has a surface step. Further, the support base 12 is provided with a heater 14 for heating the semiconductor substrate 13 and a high frequency power supply 16 for applying a high frequency to the support base 12, and a switch 15 can switch between the two. ing. The reaction gas is
It is introduced into the reaction chamber 11 through the gas inlet 17 and the exhaust port 1
After that, it is evacuated by a vacuum pump (not shown).
Further, a coil 19 is provided around the reaction chamber 11, and a high frequency power is applied to the coil 19 by a high frequency power source 20 to generate plasma in the reaction chamber 11 to cause the reaction gas to react with the coil 19. A cyclic hydrocarbon containing F and N as shown in (a) can be formed.

Table 1 shows a combination of the reaction gas, the high frequency output, and the vacuum degree, which are preferable as the plasma reaction conditions in the reaction chamber 11.

[Table 1] Here, the reaction gas is composed of lower hydrocarbons, lower fluorocarbons, and nitrogen. Among these, lower hydrocarbons are hydrocarbons having 1 to 10 carbons, and lower fluorocarbons are fluorine 1 It is preferably -20 fluorocarbons. Further, instead of one or both of these reaction gases, it is also possible to use a reaction gas composed of carbon, hydrogen and fluorine. The introduction of nitrogen, N ₂ in addition to gas, NH _3,
It is also possible to introduce in the form of N ₂ O or the like. Further, C contained in the cyclic hydrocarbon formed in the present embodiment,
H, F, and N are C: H: F: N = 20: 10: 30: 1.
Since it is preferably 0, it is preferable to adjust the ratio of each flow rate of the reaction gas introduced into the reaction chamber 11 in accordance with this. The high frequency output is preferably about 100 to 2000 W in order to obtain a stable plasma reaction.
The vacuum degree of the reaction chamber 11 is 1.0 as shown in Table 1.
It is preferably in the range of -100-100 Torr, but especially by maintaining a low vacuum of 10 Torr or less,
Polymerization of the cyclic hydrocarbon 21 containing F and N is facilitated, and the cyclic hydrocarbon polymer 22 can be formed (FIG. 1 (b)). That is, by controlling the degree of vacuum in the reaction chamber 11, the cyclic hydrocarbon 21 can be polymerized to form the cyclic hydrocarbon polymer 22. In addition to the plasma reaction, a thermal decomposition reaction or the like can be used for the reaction of the reaction gas. In addition, by using the switch 15, the high-frequency power source 1 is mounted on the support base 12.
The film forming rate of the insulating thin film 23 can be increased to about 1.5 to 3 times by connecting 6 and applying a high frequency voltage or by heating the support 12 with the heater 14.

The insulating thin film 23 made of the cyclic hydrocarbon 21 containing F or N or the polymer 22 thereof according to the embodiment of the present invention can maintain good moisture resistance and has a relative dielectric constant of 3.0 or less. Therefore, by using the insulating thin film 23, it is possible to improve the transmission delay time τ of the metal wiring 1 without lowering the moisture resistance of the insulating thin film 23. Further, the cyclic hydrocarbon 21 containing F and N is
Due to its excellent fluidity, the insulating thin film 23 formed by this
Can have good step coverage and flatness.
In particular, when the cyclic hydrocarbon forms the polymer 22, the fluidity of the cyclic hydrocarbon is further improved, and the insulating thin film 23 having better flatness can be obtained. In addition, in the present embodiment, the insulating thin film 23 has the SOG5 as in the conventional example.
Since cracks do not occur in the insulating thin film 23 even if a temperature process of 400 ° C. or higher is performed, since the insulating thin film 23 contains N and its annular structure that contribute to heat resistance improvement, The insulating thin film 23 may have good heat resistance. Further, in the present embodiment, it is possible to form the insulating thin film 23 having good step coverage and excellent flatness without using a composite process such as the conventional sandwich method.

[0014]

As is apparent from the above description, in the present invention, the insulating thin film formed on the semiconductor substrate provided with the metal wiring is formed by using the cyclic hydrocarbon containing F and N, particularly the polymer thereof. By forming it, it becomes possible to form an insulating thin film having a relative dielectric constant of 3.0 or less and excellent heat resistance while maintaining good moisture resistance. As a result, the transmission delay time τ of the metal wiring covered with the insulating thin film can be reduced without lowering the moisture resistance of the insulating thin film, and the characteristics of the semiconductor device can be improved.

Further, since the above-mentioned insulating thin film, particularly the insulating thin film formed by using the polymer of cyclic hydrocarbon is excellent in fluidity, it is possible to cover a semiconductor substrate with a step without using a composite process such as a conventional sandwich method. The insulating thin film having excellent flatness and flatness can be formed, and the manufacturing process of the semiconductor device can be simplified and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a part of a process of manufacturing a semiconductor device in which a cyclic hydrocarbon containing F or N or a polymer of cyclic hydrocarbon according to an embodiment of the present invention is used for an insulating thin film.

FIG. 2 is a schematic view of a reaction chamber used in an embodiment of the present invention.

FIG. 3 is a part of a manufacturing process of a semiconductor device in which an insulating thin film is formed by using a conventional sandwich method.

[Explanation of symbols]

1 metal wiring (step), 4 SiO ₂ film, 5 SOG,
6 SiO ₂ film, 11 reaction chamber, 12 conductive support, 1
3 semiconductor substrate, 14 heater, 15 switch, 16
High frequency power supply, 17 gas inlet, 18 exhaust, 19
Coil, 20 high frequency power source, 21 F, cyclic hydrocarbon containing N, 22 F, cyclic polymer containing N, 2
3 Insulating thin film.

Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01L 21/312 H01L 21/314 H01L 21/316 H01L 21/318

Claims (2)

(57) [Claims] 1. A semiconductor substrate provided with metal wiring on a semiconductor substrate is placed in a reaction chamber having a vacuum degree of 1.0 to 100 Torr, and a lower hydrocarbon, a lower fluorocarbon, and nitrogen are placed in the reaction chamber. The step of introducing each reaction gas, and reacting the above reaction gas by the plasma CVD method,
And a step of depositing an insulating thin film made of a cyclic hydrocarbon containing F, N or a cyclic hydrocarbon polymer containing F, N on the semiconductor substrate. 2. The degree of vacuum in the reaction chamber is 10 to 100 T.
The manufacturing method according to claim 1, wherein the manufacturing method is orr.