JPH06275721A - Thin film forming method - Google Patents

Abstract

PURPOSE:To deposit on a desired region even if two or more types of material gases are combined and material gas of a thin film material losing selectivity is supplied by laminating only material gas containing a thin film material having highest selectivity on a desired region as a first layer and using the first layer as a nucleus. CONSTITUTION:Cu is selectively deposited only in a viahole 50 from a bottom by a thermal CVD method in which gas of CpCuTEP (C5H5CuP(C2H5)3) of a Cu material and hydrogen are used as materials to form a Cu film 51. Then, an Al-Cu alloy is selectively deposited only on the film 51 in the viahole 50 by a thermal CVD method in which gas of DMAH(AlH(CH3)2) of an A material, gas of CpCuTMP of the Cu material and hydrogen are used as materials to form an AlCu alloy film 52 in the viahole 50. Thus, a via plug 53 made of the Cu film of a lower layer and the Al-Cu alloy film of an upper layer can be formed.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a chemical vapor deposition method (CV).
The present invention relates to a thin film forming method using the D method), and particularly to wiring used in a semiconductor device.

[0002]

2. Description of the Related Art In recent years, semiconductor devices have changed from LSI to VLS.
The degree of integration has been improved to I and further to ULSI, and along with this, the miniaturization of the width of the wiring and the diameter of the contact hole has been remarkably advanced. In the progress of such technological development, Cu and A have been used as wiring materials for semiconductor devices.
Technology using alloy with 1 (Japanese Patent Laid-Open No. 3-111567, etc.)
Is disclosed. Al-C consisting of Al-Cu alloy film
The u alloy wiring has characteristics that it is superior in flatness and denseness and is resistant to electromigration and stress migration as compared with an Al wiring made of only Al.

Conventionally, such an Al--Cu alloy wiring is CV
In the case of forming by the D method, the raw material gas containing the Al component and the raw material gas containing the Cu component were mixed as they were and introduced onto the substrate (JP-A-2-170419).

[0004]

[Problems to be Solved by the Invention] However, Al raw material and C
Since the thermal decomposition temperature and the deposition characteristics of the u raw material are different, the selectivity of at least one of them is lost. Specifically, since the Cu raw material decomposes at a lower temperature than the Al raw material, if the temperature at which the film is formed by the CVD method is adjusted to the Al deposition temperature, the Cu loses its selectivity and spreads over the entire surface of the substrate. There is a problem that it will be accumulated.

This is a problem naturally occurring not only in the combination of Al and Cu but also in raw materials having different deposition conditions such as thermal decomposition temperature.

Therefore, an object of the present invention is to provide a thin film forming method that solves such problems.

[0007]

In order to solve the above problems, the present invention provides a thin film forming method for forming a thin film by a chemical vapor deposition method by supplying two or more source gases containing a thin film material. A first step of supplying only a raw material gas containing a thin film material having the highest selectivity among the raw material gases and depositing the thin film material in a desired region to form a first layer; and two or more raw materials A second step of supplying all gas and further depositing a thin film material on the first layer to form a second layer.

In order to solve the above problems, the present invention provides a thin film forming method for forming a thin film by chemical vapor deposition by supplying two or more kinds of raw material gas containing a thin film material. Among them, only the source gas containing the thin film material having the highest selectivity is supplied, and the thin film material is deposited in a desired region by the chemical vapor deposition method in the hydrogen gas atmosphere.
The first step of forming a layer of, and two or more kinds of source gases are sequentially supplied from a source gas containing a highly selective thin film material,
A second step of forming a second layer by further depositing a thin film material on the first layer.

[0009]

According to the method of the first aspect, only the source gas containing the thin film material having the highest selectivity among the two or more types of source gas supplied is deposited in the desired region to form the first layer. Since the first layer is formed and has the first layer as a nucleus, even if two or more kinds of raw material gases are combined and the raw material gas of the thin film material with lost selectivity is supplied, it can be deposited in a desired region. . That is, in the second step, two or more kinds of source gases having different selectivities are supplied, but since the base that serves as the core is formed in the first step, the concentration of the supplied source gas is high in the base portion. It becomes low in the parts other than the base. In addition, since it takes a long time to form a thin film after each generation in a portion other than the underlayer, an alloy is deposited on the underlayer during that time, so that the thin film can be formed with good selectivity.

According to the method of the second aspect, only the source gas containing the thin film material having the highest selectivity among the two or more types of source gas to be supplied is deposited in the desired region, and the first source gas is deposited. Since a layer is formed and a source gas containing a thin film material is supplied in order of high selectivity with the first layer as a nucleus,
Even when forming a thin film composed of two or more kinds of layers, the selectivity can be deposited in a desired region without losing the selectivity.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description.

A method of manufacturing a semiconductor device according to an embodiment of the present invention will be described with reference to FIGS. First, as shown in FIG. 1A, a base insulating film 20 is formed on the surface of a Si substrate 10, and an Al alloy is deposited on the base insulating film 20 to a thickness of 300 to 800 nm by a sputtering method. The alloy film 31 is formed. Next, the Al alloy film 31 is processed into a predetermined wiring pattern to form the lower layer metal wiring 30. The wiring pattern is formed by RIE (reactive ion etching) using a chlorine-based gas after forming a resist pattern using an exposure device. Next, as shown in FIG. 1B, an interlayer insulating film 40 is formed on the base insulating film 20 on which the lower metal wiring 30 is formed.
The interlayer insulating film 40 is formed of Si by plasma CVD.
O ₂ is deposited to form a SiO ₂ film, and SOG (Spi
non glass) is applied to the flat portion to apply SO
It is formed by forming a G film and performing heat treatment at a necessary temperature. After that, SiO ₂ is deposited again by the plasma CVD method to form a SiO ₂ film.

Next, a photomask is set on the interlayer insulating film 40, a resist pattern is formed using an exposure device, and then RIE is performed using a fluorine-based gas as shown in FIG.
As shown in (c), a via hole 50 is formed in the interlayer insulating film 40. Next, the lower metal wiring 30 exposed at the bottom of the via hole 50 by plasma etching using a chlorine-based gas.
(Al alloy film) is cleaned. This process is performed because deposits, an alumina film and the like adhere to the surface of the lower layer metal wiring 30 exposed at the bottom of the via hole 50 during RIE and when exposed to the atmosphere after RIE. This is because the deposit and the alumina film have to be removed because they impede Al deposition in the CVD method.

Next, CpCuTEP (C
_{5 H 5 CuP (C 2 H} 5) 3: Cyclopentad
ienyl-triethylphosphine-c
The Cu film 51 is formed as shown in FIG. 2A by selectively depositing Cu from the bottom surface only in the via hole 50 by a thermal CVD method using an (operator) gas and hydrogen as raw materials. The conditions for performing the CVD at this time are a bubbling pressure of 170 Torr, a hydrogen gas flow rate of 100 sccm, and a bubbling temperature of 100 ° C. Note that this film formation CV
The total pressure in the D reaction vessel is 2 Torr, and the temperature is 200 ° C. The deposition time at this time was about 30 seconds, and the film thickness of the Cu film was 2 nm.

Next, DMAH (AlH
_{(CH 3) 2: Dimethyl-} alminum-h
gas) and CpCuTM which is a Cu raw material
As shown in FIG. 2B, by selectively depositing an Al—Cu alloy only on the Cu film 51 in the via hole 50 by a thermal CVD method using P gas and hydrogen as raw materials, the via hole 50 is formed. An Al-Cu alloy film 52 is formed inside. The conditions for performing the CVD at this time are: bubbling pressure 170 Torr, hydrogen gas flow rate 10 for CpCuTMP gas.
0 sccm, bubbling temperature 100 ℃, D
Bubbling pressure is 500 Tor for MAH gas
r, hydrogen gas flow rate 100 sccm, bubbling temperature 50
Perform at ℃. The total pressure in the CVD reaction vessel for film formation was 2 Torr and the temperature was 250 ° C. The deposition time at this time was about 5 minutes, and the thickness of the Al—Cu film was 1 μm. Thus, the via plug 53 having the lower layer of the Cu film and the upper layer of the Al—Cu alloy film is formed.

Next, an Al alloy of 400 to 400 is sputtered.
An upper layer metal wiring 60 is formed as shown in FIG. 2C by using the same method as that for forming the Al alloy film by depositing to a film thickness of 1000 nm and forming the lower layer metal wiring 30. A semiconductor device having a multilayer wiring structure is manufactured. After forming the upper layer metal wiring 60, an annealing treatment is performed to diffuse Cu atoms in the Cu film 51 into the Al alloy (or pure Al) film 52 forming the via plug 53, as shown in FIG. The entire via plug 53 may be made of an Al-Cu alloy. Further, until the semiconductor device using the via structure of the present invention is completed, a surface protective film is formed after the via plug 53 is formed, and heat treatment for removing process damage is performed.

Further, structures necessary for a semiconductor device such as a diffusion layer and a gate electrode are formed in and on the surface of the Si substrate 10. A contact hole exists at a required position of the base insulating film 20, and a contact structure for connecting the lower metal wiring 30 and the diffusion layer or the gate electrode or other structure is formed. If necessary, an antireflection film using W or the like and a barrier metal using TiN or the like are formed between the metal wiring and the insulating film. Further, one or more new interlayer insulating film 40 and metal wiring can be laminated on the upper metal wiring 60. As described above, the reason why the Cu film is formed prior to the formation of the Al—Cu alloy film is that Cu has superior selectivity to Al under the deposition conditions in this embodiment. Thus, if the Cu film is formed in advance, the Al—Cu alloy film is selectively deposited with the Cu film as the nucleus. As shown in the present embodiment, as the source gas having excellent Cu selectivity as compared with Al, there are the following materials other than those used in the present embodiment as the Al raw material and the Cu raw material.

That is, as the Al raw material, Al (CH ₃ )
₃ , Al (C ₄ H ₉ ) ₃ , AlH (C ₂ H ₅ ) ₂ , Al
_{H 3 · N (CH 3)} 3, (i-C 3 H 7) AlCl 2,
(N-C ₃ H ₇₎ there are ₂ AlCl or the like.

As the Cu raw material, Cu (aca
c) ₂ , Cu (hfac) ₂ , C ₅ H ₅ CuP (C
_{H 3) 3, (hfac)} CuP (C 2 H 5) 3, (hf
ac) CuP (2-Butyne) and the like.

Although the case where the via plug is formed has been described in the present embodiment, the thin film forming method according to the present invention is applied to a film for forming a metal wiring and a CVD method which is not limited to this and is used in another way. It goes without saying that it can also be used when forming a film to be formed.

[0021]

As described above in detail, according to the present invention, only the source gas containing the thin film material having the highest selectivity among the two or more source gases supplied is deposited in the desired region. Since the first layer is formed and the first layer serves as a nucleus, even if two or more kinds of raw material gases are combined and the raw material gas of the thin film material with lost selectivity is supplied, the desired area is provided. It can be deposited. Therefore, even if two or more kinds of source gases having different deposition conditions are used, a thin film can be formed without impairing the selectivity which is an advantage of the CVD method.

[Brief description of drawings]

FIG. 1 is a diagram showing each manufacturing process of a semiconductor device according to an embodiment of the invention.

FIG. 2 is a diagram showing each manufacturing process of the semiconductor device according to the embodiment of the invention.

FIG. 3 is a sectional view of a semiconductor device according to an example of the present invention.

[Explanation of symbols]

10 ... Si substrate, 20 ... Base insulating film, 30 ... Lower metal wiring, 40 ... Interlayer insulating film, 50 ... Via hole, 51 ... Al-
Cu alloy film, 52 ... Al film, 53 ... Via plug, 60
... Upper layer metal wiring

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tomoji Katagiri 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Corporation Technical Research Division (72) Inventor Yoyo Ota 1 Kawasaki-cho, Chuo-ku, Chiba-shi Address: Kawasaki Steel Corporation Technical Research Division

Claims (2)

[Claims] 1. A thin film forming method for forming a thin film by a chemical vapor deposition method by supplying two or more kinds of raw material gases containing a thin film material, wherein a raw material containing a thin film material having the highest selectivity among the raw material gases. A first step of supplying only gas and depositing a thin film material in a desired region to form a first layer; and supplying all of the two or more kinds of source gases, and further on the first layer, A second step of depositing a thin film material to form a second layer. 2. A thin film forming method for forming a thin film by chemical vapor deposition by supplying two or more raw material gases containing a thin film material, wherein the raw material contains a thin film material having the highest selectivity among the raw material gases. Only the gas is supplied, and the thin film material is deposited in a desired region by a chemical vapor deposition method in a hydrogen gas atmosphere.
A first step of forming a layer, and the two or more kinds of source gases are sequentially supplied from a source gas containing a highly selective thin film material, and a thin film material is further deposited on the first layer to form a first layer. And a second step of forming two layers.