Semiconductor device manufacturing: process – Making field effect device having pair of active regions... – Having insulated gate
Utility Patent
1998-06-09
2001-01-02
Elms, Richard (Department: 2824)
Semiconductor device manufacturing: process
Making field effect device having pair of active regions...
Having insulated gate
C438S308000, C438S535000, C438S798000
Utility Patent
active
06169004
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a production method for a semiconductor device. More particularly, it relates to a production method for a semiconductor device in which a film forming process, which is conventionally performed at a high temperature, can be performed at a low temperature not excluding approximately 250° C.
FIG. 7
is a schematic sectional view of a producing apparatus used in a conventional production method for a semiconductor device. As is shown in
FIG. 7
, this producing apparatus device comprises a chamber
50
that is retained to be vacuum, a substrate table
52
provided within the chamber
50
so as to place and support a semiconductor substrate thereon, an exhaust system
54
for exhausting a gas in the chamber
50
, and an ion gun
58
for emitting desired ions
56
toward the substrate table
52
.
The outline of the conventional production method for a semiconductor device, for example, a MOS transistor, will now be described referring to
FIGS. 7 and 8
.
First, the desired ions
56
are sprayed by the ion gun
58
onto the surface of a semiconductor substrate
60
made of, for example, silicon, that is supported on the substrate table
52
, thereby forming a desired impurity layer
62
on the surface of the semiconductor substrate
60
. Then, a silicon layer
64
is grown on the impurity layer
62
.
Next, the resultant semiconductor substrate
60
is charged in an electric furnace (not shown), and is allowed to stand at a high temperature in a desired oxidation atmosphere. As a result, a silicon oxide film
66
is formed on the surface of the silicon layer
64
. Then, the resultant semiconductor substrate
60
is charged in a CVD device (not shown), in which, for example, a gate electrode
68
is formed on the silicon oxide film
66
. Thus, a MOS transistor is produced.
In the aforementioned conventional method, however, the semiconductor substrate
60
is exposed to a high temperature in forming the silicon oxide film
66
in the electric furnace. Therefore, the distribution such as a sharp distribution of the impurity layer
62
formed in the previous process can be disadvantageously degraded. This will be specifically described as follows: In producing a semiconductor device, a desired amount of a desired impurity is added to a desired portion of a semiconductor substrate made of, for example, pure silicon crystal, and then, the resultant semiconductor substrate is subjected to some treatments at a high temperature such as a process for epitaxially growing a crystal film.
FIG. 9
shows a sharp distribution of an impurity in the direction of the depth of an impurity layer formed on a semiconductor substrate. Such a sharp distribution is required to be retained through the subsequent processes. When the treatment temperature in the subsequent film forming processes is high, however, the distribution of the impurity once settled is changed, resulting in a problem of spoiling the sharp distribution of the impurity.
When the treatment temperature in the subsequent film forming processes is decreased, another problem arises that a satisfactory film cannot be formed.
Further, besides the change of the distribution in the impurity layer, a high temperature at the film forming processes causes still another problem that the distribution of, for example, a compound layer such as an oxide layer, a nitride layer and a carbide layer formed in a previous process can be adversely affected.
SUMMARY OF THE INVENTION
Taking the aforementioned conventional problems into consideration, the objective of the invention is realizing a film forming process at a low temperature, which has been conventionally performed at a high temperature.
The first production method for a semiconductor device according to this invention was attained as a result of finding that a satisfactory film, which has been conventionally formed at a high temperature, can be formed at a low temperature by introducing a functional gas with irradiation by ionizing radiation or light.
The first production method for a semiconductor device comprises a step of forming a film on a semiconductor substrate having an impurity layer by introducing a functional gas on the semiconductor substrate while irradiating the semiconductor substrate with ionizing radiation or light at a temperature lower than 250° C.
When the functional gas is introduced while irradiating the semiconductor substrate with ionizing radiation or light, the functional gas is reacted with the main component of the semiconductor substrate at a low temperature not exceeding 250° C. since the functional gas is provided with energy by the ionizing radiation or light.
Further, since the film is formed at a low temperature not exceeding 250° C., the semiconductor substrate is not exposed to a high temperature, and hence, the formation of the film does not affect the distribution of the impurity in the semiconductor substrate.
Accordingly, a satisfactory film can be formed on a semiconductor substrate without affecting the distribution of the impurity in the semiconductor substrate.
In the first production method for a semiconductor device, the step of forming the film can include a step of forming a patterned film on the semiconductor substrate by exposing the semiconductor substrate with electron beams while introducing a functional gas on the semiconductor substrate.
In this case, the functional gas is reacted with the main component of the semiconductor substrate merely in an area that is exposed with the electron beams. Therefore, the patterned film can be formed on the semiconductor substrate without conducting etching. In this manner, a finely controlled pattern can be formed on a semiconductor substrate.
The second production method for a semiconductor device according to this invention comprises a step of forming a layer on a semiconductor substrate from an atom or a molecule different from the main component of the semiconductor substrate by introducing a functional gas while irradiating the semiconductor substrate with ionizing radiation or light at a temperature not exceeding 250° C.
When the functional gas is introduced while irradiating the semiconductor substrate with the ionizing radiation or light, the functional gas is reacted with the main component of the semiconductor substrate even at a low temperature not exceeding 250° C. since the functional gas is provided with energy by the ionizing radiation or light. Therefore, a layer can be satisfactorily formed from an atom or a molecule different from the main component of the semiconductor substrate.
Further, since the layer is formed at a low temperature not exceeding 250° C., the semiconductor substrate is not exposed to a high temperature, and hence, the component of the functional gas cannot be easily diffused in the semiconductor substrate. As a result, the layer can be formed without affecting the crystal structure of the semiconductor substrate.
Accordingly, it is possible to form an excellent layer on a semiconductor substrate from an atom or a molecule different from the main component of the semiconductor substrate without affecting the crystal structure of the semiconductor substrate.
In the second production method for a semiconductor device, the step of forming the layer can include a step of forming a patterned layer on the semiconductor substrate by exposing the semiconductor substrate with electron beams while introducing a functional gas on the semiconductor substrate.
In this manner, a patterned layer can be formed on a semiconductor substrate without conducting etching, and hence, it is possible to form a finely controlled pattern on a semiconductor substrate.
The third production method for a semiconductor device according to this invention is attained by applying the above-mentioned finding to a production method for a MOS transistor. This method comprises the steps of forming an impurity layer to be formed into a channel region on a semiconductor substrate by introducing a functional gas while irradiating the semiconductor subst
Mizuno Bunji
Nakayama Ichirou
Okada Kenji
Elms Richard
Lebentritt Michael S.
Matsushita Electric - Industrial Co., Ltd.
McDermott & Will & Emery
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