JPH06346240A - Formation of thin film - Google Patents

Abstract

PURPOSE:To form an AlCu alloy film excellent in uniformity and smoothness at a low cost with high productivity by supplying a raw gas contg. an Al component and a raw gas contg. the hydrate of an org. Cu(I) compd. and conducting chemical vapor deposition. CONSTITUTION:A base insulating film 20 is formed on the surface of an Si substrate 10, and a lower-layer metallic wiring 30 of specified pattern is formed thereon. An interlayer insulating film 40 of SiO2, etc., having a via hole is formed thereon. A raw gas contg. an Al component is then supplied, Al is selectively deposited in the via hole by chemical vapordeposition to form an Al layer 51. Subsequently, the hydride of an org. Cu(I) compd. is used as a raw gas contg. a Cu component to form a Cu layer 52 on the Al layer 51 in the same way, and a metallic thin film 53 consisting of plural layers of Al and Cu is obtained. An upper-layer metallic wiring 60 is then formed on the interlayer insulating film 40, and the thin film 53 is alloyed to obtain a semiconductor device of multilayer wiring structure consisting of an Al-Cu alloy and having a via plug 54.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a chemical vapor deposition method (CV).
The present invention relates to a method of forming a thin film 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, a technique of using an Al / Cu alloy film obtained by alloying a Cu film deposited by a CVD method having an excellent step coverage and an Al film by heat treatment as a wiring material of a semiconductor device (Patent Document 1) 3-47966, etc.) is disclosed. Also C
Regarding the CVD film formation of the u film, bishexafluoroacetylacetonate / copper (C
By using a hydrate of u (hfac) 2) as a raw material,
It has been reported that it is possible to improve the film formation rate and obtain a Cu film of high film quality with good uniformity and smoothness as compared with the case of using an anhydrate as a raw material (Awaya et al.,
1991 VLSI Technology Symp
osium, p. 37). It is considered that this is because the use of hydrate increased the decomposition efficiency of the raw material gas and improved the nucleus generation density on the substrate surface. The wiring made of an Al—Cu alloy film has characteristics that it is superior in flatness and denseness and is resistant to electromigration and stress migration, as compared with a wiring made of only Al.

[0003]

However, conventionally, organic A
In the case of forming an alloy film using a 1-compound and an organic Cu compound, the deposition conditions such as the decomposition temperature of each raw material gas are different, and the deposition rate of the Cu raw material itself by the CVD method is slow. It was difficult to increase the film speed. In order to improve this film forming speed, it is possible to reduce the pressure inside the bubbler containing each source gas or increase the carrier gas flow rate,
Although some improvement can be expected by this, there was a limit to that. Further, when a hydrate of a divalent compound is used as a raw material, a film forming temperature of about 350 ° C. is required for CVD film formation of a Cu film. Therefore, it is difficult to form continuously with Al that is formed at a temperature of about 150 to 300 ° C.
To form Al and Cu in separate reaction chambers after film formation, or to form films in the same reaction chamber, Al
After film formation, a step of changing the substrate temperature to a temperature for Cu film formation is required. In the former case, a complicated and expensive film forming apparatus is required, and in the latter case, productivity is lowered due to the time required for temperature change.

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

[0005]

In order to solve the above problems, the thin film forming method according to the present invention supplies a source gas containing an Al component and a source gas containing a Cu component to perform chemical vapor deposition. In the metal thin film forming method of forming a metal thin film composed of a plurality of Al layers and Cu layers in a desired region by a method, a monovalent organic Cu compound hydrate is used as a source gas containing the Cu component. It is characterized by using.

[0006]

According to the above method, when a monovalent organic Cu compound hydrate is used as the source gas for forming the Cu film,
The film formation rate and film quality can be improved as in the case of using a hydrate of a divalent organic Cu compound. Besides, 1
When a hydrate of a divalent organic Cu compound is used, it is lower than that when a hydrate of a divalent compound is used as a raw material.
Cu film formation is possible at a substrate temperature of about 50 to 250 ° C. In addition, since the hydrate of a monovalent compound has a shorter reaction path until copper reaches a metal state, it is easy to form a Cu film in which impurities such as carbon, oxygen, and fluorine due to the source gas are less likely to remain. Can be obtained.

[0007]

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 using a chlorine-based gas after forming a resist pattern using an exposure device. Next, as shown in FIG. 1B, the interlayer insulating film 40 is formed on the base insulating film 20 on which the lower metal wiring 30 is formed.
To form. The interlayer insulating film 40 is formed by depositing SiO ₂ by a plasma CVD method to form a SiO ₂ film, and
Apply OG (Spin on Glass) to SOG
A film is formed, heat treatment is performed at a necessary temperature, and then SiO ₂ is deposited again by the plasma CVD method to form Si.
An O ₂ film is formed.

Next, a photomask is set on the interlayer insulating film 40, a resist pattern is formed by using an exposure apparatus, and then RIE using a fluorine-based gas is performed.
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 must be removed because they hinder the deposition of the Al film or Cu film in the CVD method.

Next, by selectively depositing Al only in the via holes 50 by a thermal CVD method using a gas of AlH source DMAH (dimethyl aluminum hydride) and hydrogen as a source, FIG. 2A. As shown in, an Al layer 51 is formed in the via hole 50.

In addition to DMAH, TM is used as an Al raw material.
AA (trimethylamine alane), Al (CH ₃ ) ₂ H
· N (CH _{3) 3} (trimethylamine dimethylaluminum hydride), DMEAA (dimethylethylamine alane), TIBA (triisobutyl aluminum), TMA (trimethyl aluminum), etc. intermolecular compound of DMAH and TMA can be used.

Next, monovalent organic Cu compound, squiwapentadienyl triethylphosphine copper (CpC).
2 (b) by selectively depositing Cu only in the via hole 50 by a thermal CVD method using a gas of CpCuTEP.H ₂ O, which is a hydrate of uTEP), and hydrogen.
As shown in, the Cu layer 51 is formed. In addition, in order to clarify the Cu layer 51 in the drawings, the film thickness of the Cu layer 51 is drawn thicker than the heights of other elements. The hydrate gas can be supplied either by putting the hydrate in a bubbler container and passing through a carrier gas such as hydrogen, or by putting the hydrate in a bubbler container and passing through a carrier gas containing water. However, in the case of the former, there is a problem that the hydrate in the bubbler container changes to an anhydride with the aeration time, and the concentration of the hydrate gas supplied decreases, and the latter is preferable. On the other hand, in order to solve the former problem, a method in which water is included in the carrier gas even when a hydrate is placed in the bubbler container, or a carrier gas that does not contain water is usually used during film formation, There is a method of keeping the hydrated state within a certain range through a carrier containing water.

As the Cu raw material, in addition to CpCuTEP hydrate, cyclopentadienyl trimethylphosphine copper (CpCuTMP), acetylacetonate trimethylphosphine copper ((acac) CuTM)
P), acetylacetone, triethylphosphine,
Copper ((acac) CuTEP), trifluoroacetylacetonate / trimethylphosphine / copper ((tfa
c) CuTMP), trifluoroacetylacetone
Triethylphosphine / copper ((tfac) CuTE
P), hexafluoroacetylacetone, trimethylphosphine, copper ((hfac) CuTMP), hexafluoroacetylacetonate, triethylphosphine, copper ((hfac (CuTEP), hexafluoroacetylacetonate, cyclooctadiene, copper) ((Hfac
(Cu (COD)), Hexafluoroacetylacetonate / Vinyltrimethylsilane / Copper ((hfac) Cu
(VTMS)), hexafluoroacetylacetonate
2-butyne / copper ((hfac) Cu (2-butyn)
e)), hexafluoroacetylacetone, bistrimethylsilylacetylene, copper ((hfac) Cu (BT
MSA)), hexafluoroacetylacetone, 2-pentyne, copper ((hfac) Cu (2-pentyn)
Hydrates such as e)) can be used.

By using the hydrate of the monovalent organic Cu compound as described above, as in the case of using the hydrate of the divalent organic Cu compound, a high film quality with good smoothness and uniformity is obtained. The Cu film can be deposited at a high film forming rate.
Moreover, Cu film formation is possible at a substrate temperature of about 150 to 250 ° C., which is lower than when a hydrate of a divalent compound is used as a raw material. Therefore, it is possible to form a film at the same substrate temperature as that of Al, and by using an inexpensive apparatus having only a single film formation layer, high productivity, good uniformity and smoothness, and high quality AlCu An alloy film can be formed. Furthermore, since the hydrate of a monovalent compound has a shorter reaction path until copper reaches a metal state, carbon and oxygen are compared to the case where a hydrate of a divalent compound is used as a raw material. It is possible to easily obtain a Cu film in which impurities such as fluorine and fluorine resulting from the source gas are less likely to remain. Therefore, the impurity concentration in the finally obtained AlCu alloy film can also be lowered.

Next, Al is sputtered to 400 to 1 by the sputtering method.
The upper layer metal wiring 60 is formed as shown in FIG. 2C by using the same method as that for forming the lower layer metal wiring 30 by depositing the Al alloy film to a thickness of 000 nm.

Next, after forming the upper layer metal wiring 60, an annealing treatment is performed to alloy the Al layer 52 and the Cu layer forming the metal thin film 53 with each other, and a metal as shown in FIG. The entire thin film 53 is made into an Al—Cu alloy and the via plug 54 is formed to manufacture a semiconductor device having a multilayer wiring structure. The annealing treatment at this time is performed at an annealing temperature of 200 ° C. to 550 ° C. in an inert gas atmosphere or a vacuum atmosphere.
Done in. It should be noted that the time required for the annealing treatment cannot be generally specified because it changes depending on the annealing temperature.
About 30 minutes at ℃, 1 at 400 ℃
0 minutes or more is sufficient.

Further, until the semiconductor device using the via structure of the present invention is completed, a surface protective film is formed after the metal thin film 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 or a barrier metal using TiN or the like is formed between the metal wiring and the like 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. 1
H ₂ O contained in the Cu source gas in the film formation layer in the state where the Al and Cu films have been formed on the single substrate.
Remains. This H ₂ O reacts extremely well with the source gas of Al to form alumina. Therefore, it is necessary to remove H ₂ O from the inside of the film forming layer before inserting the next substrate into the film forming layer. For this purpose, for example, after taking out the substrate on which film formation has been completed, DMAH or other Al organic compound gas is supplied into the film formation layer to remove the residual H ₂ O in the form of alumina particles, and thereafter, There is a method of inserting the following board. In this embodiment, after forming the Al layer, Cu
The case of forming the layer has been described, but the Al layer may be formed after the Cu layer is formed.

Further, the Cu layer and the Al layer are not limited to one layer each as in this embodiment, and the same window and Al layer are further deposited to form a plurality of Cu layers and a plurality of Al layers. It goes without saying that a metal thin film having a plurality of layers may be formed. However, in these cases, when the films of Al and Cu are continuously formed in the same film formation layer, H ₂ O contained in the Cu source gas is completely removed before the Al source gas is removed. Is difficult to introduce in the layer,
The film quality deteriorates. DMA with the board mounted in the layer
When H or other Al organic compound gas is supplied,
This is because the alumina particles generated by the reaction with the residual H ₂ O adhere to the substrate and cause dust generation, so that the H ₂ O removal cannot be performed by this method. Therefore, Al,
It is desirable to form Cu in each dedicated film formation layer. Here, AlCu is selectively formed only in the via hole.
An example of depositing an alloy film to form a plug has been shown, but the method of forming a thin film of the present invention is also effective when depositing an AlCu alloy film on the entire surface of a substrate and then processing it into a desired wiring pattern. Is.

[0020]

As described above in detail, according to the method for forming a metal thin film of the present invention, when a monovalent organic Cu compound hydrate is used as a source gas for forming a Cu film, it is uniform. C with good film quality, smooth and smooth with few impurities
The u film can be formed at a high film forming rate and at a low film forming temperature which is almost equal to the film forming temperature of Al.

Therefore, it is possible to form an AlCu alloy film having high uniformity and smoothness and high film quality with high productivity by using an inexpensive apparatus.

[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.

[Explanation of symbols]

10 ... Si substrate, 20 ... Base insulating film, 30 ... Lower layer metal wiring, 40 ... Interlayer insulating film, 50 ... Via hole, 51 ... Al
Layer, 52 ... Cu layer, 53 ... Metal thin film, 54 ... Via plug, 60 ... Upper layer metal wiring

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Eiichi Kondo 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Corporation Technical Research Division (72) Inventor Yoyo Ota Kawasaki-cho, Chuo-ku, Chiba-shi No. 1 Kawasaki Steel Co., Ltd. Technical Research Division

Claims (1)

[Claims] 1. A source gas containing an Al component and a source gas containing a Cu component are supplied, and a metal thin film having a plurality of layers of an Al layer and a Cu layer is formed in a desired region by a chemical vapor deposition method. In the method for forming a thin film, the source gas containing the Cu component is monovalent organic Cu.
A method for forming a thin film, which comprises using a hydrate of a compound.