Semiconductor device manufacturing: process – Chemical etching – Vapor phase etching
Reexamination Certificate
2003-04-25
2004-11-30
Nhu, David (Department: 2818)
Semiconductor device manufacturing: process
Chemical etching
Vapor phase etching
C438S711000
Reexamination Certificate
active
06825126
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a manufacturing method of a semiconductor device and a substrate processing apparatus in which a thin film is formed over a substrate.
2. Description of the Related Art
As one of semiconductor manufacturing steps, there is a CVD (Chemical Vapor Deposition) step in which a predetermined film-forming process is applied to a surface of a substrate (a substrate to be processed formed on a base that is a silicon wafer, glass, or the like on which a fine electric circuit pattern is formed). In this step, the substrate is mounted in an airtight reaction chamber and heated by a heating unit provided in the chamber, and chemical reaction is caused while a source gas is being introduced onto the substrate, thereby forming a thin film uniformly on the fine electric circuit pattern formed on the substrate. In such a reaction chamber, a thin film is also formed on components other than the substrate. Such a thin film will be hereinafter called a built-up film. In a CVD apparatus shown in
FIG. 6
, a showerhead
6
and a susceptor
2
are provided in a reaction chamber
1
, and a substrate
4
is mounted on the susceptor
2
. A source gas is introduced into the reaction chamber
1
through a source supply pipe
5
connected to the showerhead
6
and supplied onto the substrate
4
via a number of holes
8
provided in the showerhead
6
. The gas supplied onto the substrate
4
is exhausted through an exhaust pipe
7
. The substrate
4
is heated by a heater
3
provided under the susceptor
2
. Note that a built-up film is accumulated and deposited on components around the substrate such as the showerhead
6
, the susceptor
2
, and so on in accordance with increase in the number of substrates processed, in other words, increase in the number of processing times.
As such a CVD apparatus, there is a CVD apparatus that uses a MOCYD (Metal Organic Chemical Vapor Deposition) method with which an amorphous HfO
2
film and an amorphous Hf silicate film (they are hereinafter abbreviated to an a-HfO film), an amorphous Ta
2
O
5
film (it is hereinafter abbreviated to an a-TaO film), and an amorphous Ru film and an amorphous RuO
2
film (they are hereinafter abbreviated to an a-Ru film) can be formed by using an organic chemical material as a film-forming source.
As the film-forming source, Hf[OC(CH
3
)
3
]
4
(hereinafter, abbreviated to Hf—(OtBu)
4
), Hf[OC(CH
3
)
2
CH
2
OCH
3
]
4
(hereinafter, abbreviated to Hf-(MMP)
4
(here, MMP: 1methoxy-2-methyl-2-propoxy)), Hf[O—Si—(CH
3
)]
4
(hereinafter, abbreviated to Hf—(OSi)
4
), and the like are used for forming the a-HfO film; Ta(OC
2
H
5
)
5
(hereinafter, abbreviated to PETa) and the like are used for forming the a-TaO film; and Ru(CH
2
C
5
H
4
)
2
(hereinafter, abbreviated to Ru(EtCp)
2
) and the like are used for forming the a-Ru film.
Among them, many organic materials, for example, Hf—(OtBu)
4
, Hf-(MMP)
4
, PETa, Ru(EtCp)
2
, and so on are in liquid phase at normal temperatures and pressures. Therefore, these organic liquid sources are heated and thus transformed to gas by vapor pressure for utilization.
[Patent Document 1]
Japanese Patent Laid-open No. 2001-237397 (pages 4 to 7,
FIG. 5
)
[Patent Document 2]
Japanese Patent Laid-open No. 2000-235962 (page 3, FIG. 1)
[Patent Document 3]
Japanese Patent Laid-open No. Hei 11-217672 (pages 6 to 8, FIG. 1)
The built-up film is constantly deposited in the reaction chamber of the MOCVD apparatus as described above, and H
2
, H
2
O, CO, CO
2
, CH
4
, and the like are constantly coming out as eliminated gases from this built-up film. This is because a thin film such as the a-HfO film, a-TaO-film, and a-Ru film deposited with good coverage by a conventional MOCVD method contains a large amount of C, H, OH, and the like as impurities, H
2
O among these eliminated gases gives an extremely significant influence to the substrate to be processed. For example, when the substrate to be processed is an Si substrate, H
2
O modifies the surface of the substrate to a low quality oxide or hydroxide such as Si—OH or SiOx(x<2), and consequently, turns out to be a factor of greatly lowering the properties of a semiconductor device that is an end product, which poses a big problem.
Presently, in order to avoid such a serious situation, an enormous amount of labor and expenses are spent for alleviating the adverse effect of H
2
O in the MOCVD reaction chamber and the adverse effect of H
2
O which occurs due to elimination from X—OH (X═Hf, Zr, Ta, Ru, or the like) contained in a MOCVD thin film by, for example, subjecting the surface of the Si substrate to a substrate surface modifying process such as nitridation, oxidation, oxynitridation, or CVD-TIN process in advance to form a barrier layer against H
2
O.
The thin film deposited using the MOCVD method as described above has a disadvantage that flatness of a film surface is difficult to obtain. Especially, in the MOCVD method in the case when the thin film deposit rate is determined by surface reaction rate controlling conditions, the abovementioned problem is obvious. It is known that the thin film starts to be deposited on the substrate surface with a certain time lag in the surface reaction rate controlling conditions. This time lag is called an incubation time. During this incubation time, there is a nucleation process in which an island-shaped deposition is made on the substrate, and it is thought that the thin film loses its flatness due to the formation of irregularities in this nucleation process.
Such lack in flatness on the thin film surface becomes a cause of lowering reliability of a semiconductor device product that is an end product, and is becoming a significant problem in accordance with downsizing of the device.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a manufacturing method of a semiconductor device and a substrate processing apparatus capable of effectively and efficiently inhibiting the influence of an eliminated gas from a built-up film deposited in a reaction chamber of a MOCVD apparatus and reducing an incubation time to improve flatness of a thin film. It is another object of the present invention to provide a manufacturing method of a semiconductor device and a substrate processing apparatus capable of greatly saving an enormous amount of labor and expenses which have been conventionally spent for improving the aforesaid serious situation and simplifying a substrate surface modifying process so as to concentrate this process in a MOCVD apparatus, thereby greatly reducing production cost. It is still another object of the present invention to provide a manufacturing method of a semiconductor device and a substrate processing apparatus capable of inhibiting the influence of an eliminated gas from a built-up film deposited in a reaction chamber of a MOCVD apparatus and improving flatness of a thin film, without lowering productivity.
A first invention is a manufacturing method of a semiconductor device which is characterized in that it includes: a preprocess step of performing a preprocess to a substrate from which a natural oxide film is removed; and a film-forming step, subsequent to the preprocess step, of forming a metal thin film or a metal oxide thin film over the substrate, the preprocess step including a nitrogen preprocess step of activating a nitrogen (N)-containing gas and supplying the activated nitrogen-containing gas to the substrate and an oxygen preprocess step of activating an oxygen (O)-containing gas and supplying the activated oxygen-containing gas to the substrate. The preprocess step makes it possible to effectively and efficiently inhibit the influence of an eliminated gas from a built-up film and reduce an incubation time to improve flatness of the film formed in the film-forming step. Moreover, since the preprocess step includes the nitrogen preprocess step and the oxygen preprocess step, the quality of a semiconductor device can b
Asai Masayuki
Horii Sadayoshi
Kitayama Kanako
Tsuneda Masayuki
Hitachi Kokusai Electric Inc.
Nhu David
Oliff & Berridg,e PLC
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