JP3283344B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION This invention, in the manufacturing method of the semiconductor element, an insulating film, and in particular the formation of electrically insulating interlayer insulating film between wirings.

[0002]

2. Description of the Related Art Conventionally, as an insulating film of a semiconductor device, a silicon oxide film (SiO ₂ ) using a plasma enhanced chemical vapor deposition (PE-CVD) method has been widely used. However,
With the advancement of miniaturization and high integration of elements, the capacitance between wirings has increased, which has affected the driving force of elements as circuits. Therefore, there is an increasing demand for an insulating film having a low dielectric constant. As a method for forming such an insulating film having a low dielectric constant, Japanese Patent Application No. 5-88991 filed earlier by the present inventors has filed.
As described in the specification, at the time of forming a SiO ₂ film 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. Then, a method of forming a film having a composition of SiO _x F _y is performed. The method of forming this SiO _x F _y film is as follows.
For example, a parallel plate type PE having a power supply frequency of 13.56 MHz
Using a CVD apparatus and using TEOS (also referred to as tetraethylorthosilicate or tetraethoxysilane) 400 cc / min, O ₂ 400 cc / mi
n, C ₂ F ₆ 200 cc / min, RF (Radio
Freq u ency) power 2W / cm ^2, pressure 10T
orr, a temperature of 350 ° C., and a distance between the electrodes of 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 3.0.
3.8, and SiO ₂ (hereinafter, referred to as PE-CVD)
The relative dielectric constant of the film is clearly smaller than 3.9 to 5.0 (it is described as P-SiO ₂ , which is basically a kind of SiO ₂ ), and the capacitance between wirings can be reduced.

[0004]

However, the insulating film having the composition of SiO _x F _y described above has high hygroscopicity,
Since a large amount of moisture is absorbed in the film, it causes corrosion of metal wiring and deteriorates the life of a transistor, which is one of the components of a semiconductor element.

The present invention solves the above-mentioned problem that the SiO _x F _y film has high hygroscopicity and impairs the reliability of the semiconductor device. Therefore, when forming a P-SiO ₂ film, F atoms (hereinafter simply referred to as F) are formed. ) is reacted with a gas containing, SiO ₂ film and the S
An object is to obtain a highly reliable semiconductor element by reducing the hygroscopicity of the entire insulating film by forming an iO _x F _y film in a stacked manner.

[0006]

For the purposes achieved SUMMARY OF THE INVENTION The present invention is in the insulating film (mainly the interlayer insulating film) formed, in a way we describe below, and a P-SiO ₂ film and the SiO _x F _y layer It has a laminated structure.

[0007]

That is, after forming a thin P-SiO ₂ film, plasma discharge is performed by flowing only a gas containing F in the same apparatus to convert the surface of the P-SiO ₂ film into SiO _x F _y , and this is repeated. Thereby, the laminated structure is formed.

[0009]

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

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the first embodiment of the present invention,
FIG. 1 is a schematic cross-sectional view, and FIG. 2 is a timing chart of introducing various gases into the PE-CVD apparatus at the time of forming the insulating film, which will be described below.

First, as shown in FIG.
Is set in a parallel plate type PE-CVD apparatus, and TEOS
And an O ₂ gas alone (region A in FIG. 2), and a P-SiO ₂ film 12 is formed 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, C ₂ F ₆ (as described above, The gas may be another gas containing F, for example, CF ₄ , NF ₃ , HF, or the like. The gas is added (intermittently added as shown in a region B in FIG. 2) to form the SiO _x F _y film 13. The P
-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 generated at the time when the gas does not flow (region A in FIG. 2), and as shown in FIG. ), The F-SiO ₂ film 12 and the SiO _x F _y film 13
Are alternately formed, and as a result, a laminated structure of the two films 12 and 13 is formed.

FIG. 3 is a schematic cross-sectional view showing a step of forming an insulating film according to a second embodiment of the present invention, and FIG. 4 is a timing chart of gas introduction during the formation of the insulating film. I do.

First, as shown in FIG.
Is set in a 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 a substrate 21.

Thereafter, 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 converted to SiO _x F _y .
Therefore, when the above-described 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 obtained.

According to the method of the embodiment described above, P-SiO ₂
When the laminated structure of the films 12 and 22 and the SiO _x F _y films 13 and 23 is formed at a film thickness ratio of the two films of 1: 1, a P-SiO ₂ film having a relative dielectric constant of 4.2 and a 3.0 are formed. When the SiO _x F _y film is used, the relative dielectric constant of the laminated film is about 3.5, and the decrease in the dielectric constant is sufficient as an effect.

FIGS. 5A and 5B show SiO _x F _y.
FTIR (Fourier Transform Infrared Spectroscopy: As is well known, this is a typical method of spectrum analysis) in the case of the film alone and in the case of the laminated film of this embodiment immediately after formation and after leaving the film in the air for 150 hours. The absorption spectrum is shown for reference. As shown in FIG. 5A, immediately after the formation, the peaks of H ₂ O (ie, water, wave number around 3400 cm ⁻¹ ) and SiOH (around 3650 cm ⁻¹ ) were small and occluded in both films. Almost no moisture. Although both absorb water while being left in the air, as shown in FIG. 5B, in the spectrum after 150 hours, the hygroscopicity of the laminated film of this example is only the SiO _x F _y film. Compared to
It can be seen 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.

In this embodiment described above, a parallel plate type PE-CVD apparatus is used as a forming apparatus. However, other types of PE-CVD apparatus can be used. The method of switching the gas introduction in the CVD apparatus has not been particularly described, but such a means has been used in this apparatus for many years before this description, so that the description is omitted. Further, P-SiO ₂
As a film forming gas, SiH ₄ and N
Other gases such as ₂ O may be used. In addition to SiO2
_{The two} films 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 a laminated structure of the P-SiO ₂ film and the SiO _x F _y film, it has low hygroscopicity (in the case where only the SiO _x F _y film is used). (Less than half the thickness) of the insulating film (of course, the dielectric constant is as low as before) can be realized, and the problems of corrosion of metal wiring and deterioration of transistor life can be solved, and the dielectric constant is low and the driving force of the element is high and the reliability is high. A semiconductor device can be realized.

[Brief description of the drawings]

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

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

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

FIG. 4 is a timing chart for introducing a generated gas in a second embodiment.

FIG. 5 is an FTIR of SiO _x F _y and the laminated film of the present embodiment.
Comparison of absorption spectra

[Explanation of symbols]

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

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/768 H01L 21/3205 H01L 21/31 H01L 21/205

Claims (1)

(57) [Claims] 1. A method for forming an insulating film in a semiconductor element, wherein a semiconductor substrate is set in an apparatus for forming the insulating film, and a gas for forming an SiO ₂ film is introduced into the apparatus. At the same time as the introduction of SiO ₂ was stopped.
Introducing a gas to SiO _x F _y the membrane surface, by repeating the steps of introducing a gas to form a stop at the same time again the SiO ₂ film the gas introduction, the SiO ₂ film and the surface of the film is of A method of manufacturing a semiconductor device, comprising forming a laminated film with a chemically modified SiO _x F _y film on the semiconductor substrate.