Semiconductor device manufacturing: process – Coating of substrate containing semiconductor region or of... – Insulative material deposited upon semiconductive substrate
Reexamination Certificate
2003-02-28
2004-09-07
Ghyka, Alexander (Department: 2812)
Semiconductor device manufacturing: process
Coating of substrate containing semiconductor region or of...
Insulative material deposited upon semiconductive substrate
C438S681000, C438S685000, C438S778000
Reexamination Certificate
active
06787481
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method for manufacturing a semiconductor device wherein a thin film is formed on a substrate.
2. Description of the Related Art
In semiconductor manufacturing processes, there is a CVD (Chemical Vapor Deposition) process in which a prescribed film formation process is performed on a surface of a substrate (a substrate to be processed which is based on a silicon wafer, a glass and the like, on which a fine electric circuit pattern is produced). In this CVD process, the substrate is loaded into a gas-tight reaction chamber, the substrate is heated by a heating means provided in the chamber, and a chemical reaction is allowed to occur while introducing a film formation gas on the substrate, to uniformly form a thin film on the fine electric circuit pattern provided on the substrate. In such a reaction chamber, the thin film is also formed on a structure besides the substrate. In a CVD apparatus as shown in
FIG. 19
, a shower head
6
and a susceptor
2
is provided in a reaction chamber
1
, and a substrate
4
is disposed on the susceptor
2
. A film formation gas is introduced into the reaction chamber
1
through a raw material supply tube
5
which is connected to the shower head
6
, and supplied on the substrate
4
through a plurality of apertures
8
which are provided in the shower head
6
. The gas which is supplied on the substrate
4
is subjected to an exhaust process through an exhaust tube
7
. In addition, the substrate
4
is heated by a heater
3
which is provided below the susceptor
2
.
As such a CVD apparatus, there is an ALD (Atomic Layer Deposition) apparatus or an MOCVD (Metal Organic Chemical Vapor Deposition) apparatus for forming an amorphous HfO
2
film or an amorphous Hf silicate film using an organic chemical material as a film formation raw material (the amorphous HfO
2
film and the amorphous Hf silicate film being hereinafter simply abbreviated as an HfO film). Here, the differences between the CVD method performed by the MOCVD apparatus and the ALD method performed by the ALD apparatus are as follows. The ALD method is performed at a low process temperature and under a low pressure to form a film by one atomic layer at a time. On the contrary, the CVD method is performed at a higher process temperature and under a higher pressure than those of the ALD method to form a film by approximately a ⅙ atomic layer to tens of atomic layers at a time.
The film formation raw material which includes:
Hf[OC(CH
3
)
3
]
4
(hereinafter abbreviated as Hf-(OtBu)
4
);
Hf[OC(CH
3
)
2
CH
2
OCH
3
]
4
(hereinafter abbreviated as Hf-(MMP)
4
) where MMP: methylmethoxypropoxy;
Hf[O—Si—(CH
3
)
3
]
4
; and the like, is used.
In such materials, most organic materials, for example, Hf-(OtBu)
4
and Hf-(MMP)
4
, are in a liquid phase at ordinary temperature and ordinary pressure. As a result, for example, Hf-(MMP)
4
is heated and changed into a gas due to a vapor pressure and is utilized. Utilizing such a raw material and using the above-described CVD method, an HfO film is formed, for example, at a substrate temperature of 450° C. or lower. This HfO film contains impurities such as CH, OH and the like, in large quantity, for example, in an amount of several percent (%), which result from the organic material. Consequently, as a classification indicating an electrical property of a substance, the HfO film belongs to a semiconductor or conductor which is contrary to the intention of ensuring an electrical insulator.
In order to ensure electrical insulation of such a thin film and stability of the film, conventionally, an attempt has been made to allow C and H to leave the HfO film so as to convert it into an densified stable insulator thin film, by performing on the HfO film a rapid annealing treatment (hereinafter abbreviated as an RTA (Rapid Thermal Annealing)) at a temperature of 650° C. to 800° C. in an atmosphere of O
2
or N
2
. Here, an aim of the RTA is to allow the impurities such as C, H and the like, in a film to leave the film and is to densify the film. Although the densification is not performed up to crystallization, the densification is performed in order to allow a mean interatomic distance in an amorphous state to be shorter.
In
FIG. 20
, there is shown a cluster apparatus construction in a conventional method for forming an HfO film. A substrate is loaded into a load-lock chamber
32
. In a first reaction chamber
33
, a substrate surface treatment such as RCA cleaning (a typical cleaning method based on hydrogen peroxide) and the like, is performed. In a second reaction chamber
34
, an HfO film according to a method corresponding to the above-described method is formed. In a third reaction chamber
35
, an RTA treatment (an impurity removal, thermal annealing treatment) is performed. In a fourth reaction chamber
36
, an electrode (for example, a poly-Si thin film and the like) is formed. The substrate on which the electrode is formed is unloaded from the load-lock chamber
32
to an outside of the apparatus. The above carrying-in and carrying-out are performed using a substrate transfer robot
31
provided in a substrate transfer chamber
30
.
In the third chamber
35
, when C and H are allowed to leave the HfO film by the RTA treatment, there arises a problem that a surface state of the HfO film loses evenness and changes into an uneven surface state. Further, the HfO film tends to partially crystallize by the RTA treatment so that a large current becomes apt to pass through a crystal grain boundary to cause a problem that the insulation and stability of the film are impaired, which is contrary to the intention. These problems which are not limited to an insulator are common to all thin film deposition methods which utilize an ALD method or an MOCVD method in which a organic chemical material is used.
Moreover, in the second reaction chamber
34
, a thin film is also formed on a structure besides a substrate. This is referred to as an accumulated film in which a large quantity of C and H are also mixed. As a result, amounts of C and H leaving the accumulated film increase with increasing number of the processed substrates, and amounts of C and H mixed and contained in the HfO film gradually increase with increasing number of the processed substrates. Due to this phenomenon, it is very difficult to allow the quality of the continuously produced HfO films to be constant. Therefore, in order to solve the critical phenomenon, it becomes necessary to frequently practice a removal process of an accumulated film by self-cleaning, which becomes a factor that decreases productivity.
As stated above, in the conventional technique for forming an amorphous thin film, there are problems that the surface state of an HfO film loses evenness by an RTA treatment and changes into an uneven surface state, and that the HfO film partially crystallizes by the RTA treatment so as to allow a crystal grain boundary to occur so that the insulation and stability of the film are lowered.
Furthermore, in order to allow the quality of continuously produced HfO films to be constant, it is necessary to frequently practice a cleaning process of an accumulated film in which a large quantity of C and H are mixed. As a result, the productivity is reduced.
In addition, as a thin film formation technique, which does not relate to an HfO film, a method for repeating in a same reaction chamber a Ta
2
O
5
film formation and a modification process two or more times (for example, refer to Patent Document 1), a method for repeating in a same reaction chamber a film formation process of a high dielectric constant oxide film and a ferroelectrics oxide film and a heat treatment with plasma generated by using an oxidative atmospheric gas two or more times (for example, refer to Patent Document 2), and a method for repeating a metal film formation process and a metal nitride film formation process by introducing a nitriding material gas two or more times (for example, refer to P
Asai Masayuki
Horii Sadayoshi
Nomura Hisashi
Ghyka Alexander
Hitachi Kokusai Electric Inc.
Oliff & Berridg,e PLC
LandOfFree
Method for manufacturing semiconductor device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for manufacturing semiconductor device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for manufacturing semiconductor device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3244332