JPH0729975A - Semiconductor element and its manufacture - Google Patents

Abstract

PURPOSE:To reduce humidity absorption property of an entire of an insulation film and to improve reliability by forming an insulating film of a semiconductor element of a laminating film of an SiO2 film and an SiOxFy film. CONSTITUTION:In forming an insulating film (mainly a layer insulating film), a P-SiO2 film 12 and an SiOxFy film 13, for example, are formed to a laminating structure. In the process, F-containing gas (such as C2F6 gas) is added in continuation (pulse) during formation of the P-SiO2 film 12 and a lamination structure is formed. Otherwise, after the P-SiO2 film 12 is formed thin, F-containing gas alone is made to flow in the same device, plasma discharge is carried out, and a surface of the P-SiO2 film 12 is processed to SiOxFy. The laminating structure is realized by repeating the processes. Thereby, humidity absorption properties of an entire of an insulating film can be reduced and reliability can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor element and a method of manufacturing the same, and more particularly to the formation of an insulating film, particularly an interlayer insulating film for electrically insulating between wirings.

[0002]

2. Description of the Related Art Conventionally, a silicon oxide film (SiO ₂ ) using a plasma chemical vapor deposition (PE-CVD) method has been widely used as an insulating film of a semiconductor device. However,
With the progress of miniaturization and high integration of elements, the capacitance between wirings has increased to affect the driving force of elements as a circuit. Therefore, there is an increasing demand for an insulating film having a low dielectric constant, and a method for forming such an insulating film having a low dielectric constant is described in Japanese Patent Application No. 5-89891 filed by the present inventors. As described above, when the SiO ₂ film is formed by the PE-CVD method, an etching gas containing F atoms (for example, C ₂ F ₆ , CF ₄ , NF ₃ , HF, etc.) is added to make the composition SiO _x. A method of forming a film that is F _y is practiced. This SiO _x F _y film is formed by, for example, a parallel plate PE-C having a power supply frequency of 13.56 MHz.
TEOS (also called tetraethyl orthosilicate or tetraethoxysilane) 400 cc / min, O ₂ 400 cc / min, as a product gas using a VD device
C ₂ F ₆ 200 cc / min, RF (Radio Fr
power) 2 W / cm ² , pressure 10 Tor
r, temperature 350 ° C., distance between electrodes 5 mm. As described above, the C ₂ F ₆ gas may be another gas containing F.

The relative dielectric constant of this SiO _x F _y film is 3.0 to
3.8, and SiO ₂ (hereinafter,
Referred to as P-SiO _2, but in short, which is a kind of SiO ₂₎ is clear when compared with the dielectric constant from 3.9 to 5.0 of the film small, it is possible to reduce the capacitance between wirings.

[0004]

However, the above-mentioned insulating film having a composition of SiO _x F _y has a high hygroscopic property,
Since a large amount of water is occluded in the film, it causes corrosion of the metal wiring and deteriorates the life of the transistor which is one of the constituent elements of the semiconductor element.

The present invention solves the above-mentioned problem that the SiO _x F _y film has a high hygroscopic property and impairs the reliability of the semiconductor element. Therefore, when the P-SiO ₂ film is formed, an F atom (hereinafter referred to simply as F) is used. ) Is applied (by two methods as described later) to form the SiO ₂ film and the SiO _x F _y film in a laminated manner, thereby reducing the hygroscopicity of the entire insulating film. The purpose is to obtain a highly reliable semiconductor element.

[0006]

In order to achieve the above object, the present invention uses two methods described below in forming an insulating film (mainly an interlayer insulating film) by a P-SiO ₂ film and a SiO _x film.
The F _y film has a laminated structure.

(1) As a first embodiment, P-SiO ₂
During the film formation, a gas containing F is intermittently (pulsed) added to form the laminated structure.

(2) As a second embodiment, P-SiO ₂
After forming a thin film, only a gas containing F is caused to flow in the same device for plasma discharge, and the surface of the P-SiO ₂ film is changed to SiO _2.
It is _x F _y of, by repeating this, and the laminated structure.

[0009]

As described above, according to the present invention, the insulating film is made of P-SiO.
Insulating film with low hygroscopicity (less than half of the case of only SiO _x F _y film as described later) because of the laminated structure of ₂ films and SiO _x F _y film (of course, the dielectric constant is also low as before) Can be realized, and the reliability of the semiconductor element can be improved.

[0010]

EXAMPLE The insulating film forming process of the first example of the present invention
A schematic cross-sectional view is shown in FIG. 1, and a timing chart for introducing various gases into the PE-CVD apparatus at the time of forming the insulating film is shown in FIG. 2, which will be described below.

First, as shown in FIG. 1A, the substrate 11
Is set in a parallel plate PE-CVD apparatus, and TEOS
And O ₂ gas are introduced (region A in FIG. 2) to form a P-SiO ₂ film 12 on the substrate 11 by PE-CVD.

Thereafter, as shown in FIG. 1B, while the TEOS and the O ₂ gas are continuously flowing in the apparatus, the C ₂ F ₆ (as described above, The gas may be another gas containing F, such as CF ₄ , NF ₃ , or HF.) By adding (intermittently adding as shown in region B of FIG. 2) the SiO _x F _y film 13 is added. The P
It is formed on the —SiO ₂ film 12.

As described above, since the C ₂ F ₆ gas is intermittently introduced, the P-SiO ₂ film 12 is formed at the time when the gas does not flow (region A in FIG. 2), and the P-SiO ₂ film 12 is generated as shown in FIG. ), The F-SiO ₂ film 12 and the SiO _x F _y film 13 are
Are alternately formed, and as a result, a laminated structure of the both films 12 and 13 is formed.

FIG. 3 shows a schematic cross-sectional view of an insulating film forming step of the second embodiment of the present invention, and FIG. 4 shows a timing chart of gas introduction at the time of forming the insulating film, which will be described below. To do.

First, as shown in FIG. 3A, the substrate 21
Is set in the PE-CVD apparatus as in the first embodiment, TEOS and O ₂ gas are introduced (region C in FIG. 4),
A P-SiO ₂ film 22 is formed on the substrate 21.

After that, the introduction of the TEOS and the O ₂ gas is stopped, and at the same time, the C ₂ F ₆ gas is introduced to perform plasma discharge (region D in FIG. 4). Then, as shown in FIG. 3B, the P-SiO ₂ film 22 is slightly etched, but the surface becomes a layer (film) 23 made into SiO _x F _y .
Therefore, when the above-mentioned gas introduction is alternately repeated as in the regions C and D shown in FIG. 4, as shown in FIG.
A laminated structure of the —SiO ₂ film 22 and the SiO _x F _y film 23 is formed.

By the method of the above-mentioned embodiment, P-SiO ₂
When a laminated structure of the films 12 and 22 and the SiO _x F _y films 13 and 23 is formed with a film thickness ratio of the both films of 1: 1, a P-SiO ₂ film having a relative dielectric constant of 4.2 and 3.0 When the SiO _x F _y film is used, the relative dielectric constant of the laminated film is about 3.5, and the reduction of the dielectric constant is sufficient as an effect.

In FIGS. 5A and 5B, SiO _x F _{y is shown.}
FTIR (Fourier Transform Infrared Spectroscopy: As is well known, this is a typical method of spectrum analysis, in the case of only the film and in the case of the laminated film of this example, immediately after formation and after being left in the atmosphere for 150 hours. The absorption spectrum is shown for reference. As shown in FIG. 5 (a), immediately after the forming, the both films both H ₂ O (i.e. moisture, wavenumber of around 3400 cm ^-1), the peak of SiOH (3650 cm around ^-1) occluded in the small film There is almost no water. Both of them absorb water while being left in the atmosphere, but as shown in FIG. 5B, the hygroscopicity of the laminated film of this example is only the SiO _x F _y film in the spectrum after the lapse of 150 hours. Compared to
You can see that it is less than half. That is, the laminated film of this embodiment can realize an insulating film having a sufficiently low dielectric constant and a low hygroscopicity.

Although the parallel plate type PE-CVD apparatus is used as the forming apparatus in the above-described embodiment, it is of course possible to use another type of PE-CVD apparatus. Although the method of switching the gas introduction in the CVD apparatus was not particularly described, such a means has been practiced in the apparatus for many years before this description, so the description thereof is omitted. Furthermore, P-SiO ₂
As the film forming gas, SiH ₄ and N other than the above-mentioned gases are used.
Other gas such as ₂ O may be used. Furthermore, it is SiO
_{The 2} film and the SiO _x F _y film may be formed discontinuously, but it is not practical because the forming process takes time.

[0020]

As described above, according to the present invention, since the insulating film has the laminated structure of the P-SiO ₂ film and the SiO _x F _y film, the hygroscopic property is low (in the case of only the SiO _x F _y film). (Less than half of that of conventional products) (of course, the permittivity is also low as in the past), the problems of corrosion of metal wiring and deterioration of transistor life can be solved, and the permittivity is low and the driving force of the device is high. A semiconductor device can be realized.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a forming process according to a first embodiment of the present invention.

FIG. 2 is a timing chart of introduction of generated gas in the first embodiment.

FIG. 3 is a schematic sectional view of a forming process according to a second embodiment of the present invention.

FIG. 4 is a timing chart of introduction of generated gas in the second embodiment.

FIG. 5: FTIR of SiO _x F _y and the laminated film of this example
Absorption spectrum comparison chart

[Explanation of symbols]

11 substrate 12 P-SiO ₂ film 13 SiO _x F _y layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H01L 21/316 X 7352-4M 21/3205 8826-4M H01L 21/88 K

Claims (3)

[Claims] 1. A semiconductor device comprising a laminated film of a SiO ₂ film and a SiO _x F _y film as an insulating film of the semiconductor device. 2. A method of forming an insulating film in a semiconductor device, wherein a semiconductor substrate is set in an apparatus for forming the insulating film, and a gas for forming a SiO ₂ film is introduced into the apparatus, and the gas is introduced. During continuous introduction of SiO _x
A gas for forming the F _y film is intermittently introduced to produce the SiO ₂ film.
A method of manufacturing a semiconductor device, comprising: forming a laminated film of a film and a SiO _x F _y film on the semiconductor substrate. 3. A method for forming an insulating film in a semiconductor device, wherein a semiconductor substrate is set in an apparatus for forming the insulating film, and a gas for forming a SiO ₂ film is introduced into the apparatus, and the gas is used. At the same time stopping the introduction of said SiO ₂
By introducing a gas for converting the film surface into SiO _x F _y , stopping the gas introduction, and at the same time introducing a gas for forming the SiO ₂ film again, the SiO ₂ film and the surface of the film are A method of manufacturing a semiconductor device, comprising: forming a laminated film with a SiO _x F _y film chemically changed by means on the semiconductor substrate.