Semiconductor device manufacturing: process – Formation of semiconductive active region on any substrate – Fluid growth from gaseous state combined with preceding...
Reexamination Certificate
1998-05-08
2001-06-26
Smith, Matthew (Department: 2825)
Semiconductor device manufacturing: process
Formation of semiconductive active region on any substrate
Fluid growth from gaseous state combined with preceding...
C438S506000, C438S406000, C438S458000
Reexamination Certificate
active
06251754
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application is based upon and claims the benefit of priority of Japanese Patent Appliocations No. H.9-119228 filed on May 9, 1997, No. H.9-125506 filed on May 15, 1997, No. H.9-141671 filed on May 30, 1997, and No. H.9-231189 filed on Aug. 27, 1997, the contents of which are incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method for manufacturing a semiconductor substrate comprising a semiconductor layer for device formation provided on a supporting substrate and insulated from the supporting substrate.
2. Related Art
As one type of semiconductor substrates, there is a SOI (Silicon On Insulator) substrate made by providing a monocrystalline silicon layer on a silicon substrate and interposing an insulating film therebetween. As a method for manufacturing a SOI substrate of this kind, so-called smart cut methods using lamination, of the kind shown in for example Japanese Patent Application Laid-Open No. H.5-211128, have been proposed.
In this method, as shown in
FIGS. 16A through 16D
, a SOI substrate is manufactured in three stages (steps). In the first stage, as shown in
FIG. 16A
, ions obtained by ionizing, for example, hydrogen gas are accelerated with a predetermined implantation energy and implanted into a base substrate
1
made of monocrystalline silicon. In this way, a defective layer
2
is formed at a predetermined depth in the base substrate
1
. Here, a layer of the base substrate
1
above the defective layer
2
constitutes a thin film layer
1
a
eventually to become a monocrystalline silicon layer for device formation.
In the second stage, as shown in
FIG. 16B
, a supporting substrate
3
made of, for example, silicon is laminated to the upper face of the base substrate
1
. At this time, an insulating film
4
consisting of an oxide film has been formed on the surface (in
FIG. 16B
, the lower surface) of the supporting substrate
3
in advance. Then, in the third stage, as shown in
FIG. 16C
, by heat treatment, the thin film layer
1
a
is detached from the base substrate
1
along the defective layer
2
.
In this way, the thin film layer
1
a
is laminated to the insulating film
4
on the supporting substrate
3
. After that, as shown in
FIG. 16D
, by polishing of the detachment face being carried out, a SOI substrate
6
having a monosilicon layer
5
is obtained. With this method, it is possible to obtain a monosilicon layer
5
of high quality. Also, the base substrate
1
, while being reduced in thickness, can be reused.
When this kind of SOI substrate
6
is to be used, for example, for a power device or a surface micromachine, the monosilicon layer
5
is required to have a high thickness (for example several micrometers to several tens of micrometers). However, with the related art manufacturing method described above, to make the monosilicon layer
5
sufficiently thick it is necessary to make the ion implantation deep (make the position at which the defective layer
2
is formed deep).
Consequently, the ion implantation energy is high and a large amount of ion beam current is required. Also, an expensive ion implantation apparatus is also needed. In this case, to form a monosilicon layer
5
of thickness for example 10 &mgr;m, an ion implantation energy of over 1 MeV is necessary. Also, there has been the problem that there is increased contamination by impurities such as heavy metals and damage in the thin film layer
1
a
and hence the monosilicon layer
5
due to heavy metal knock-on to the inside of the thin film layer
1
a
(the monosilicon layer
5
) occurring incidentally along with the use of greater acceleration energies. Furthermore, it is not possible to reuse the base substrate
1
many times.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a semiconductor substrate manufacturing method with which, in manufacturing a semiconductor substrate having a semiconductor layer on a supporting substrate, it is possible to obtain a thick semiconductor layer with a simple process and cheaply.
It is an another object of the present invention to provide a semiconductor substrate manufacturing method with which it is possible to suppress impurity contamination of the semiconductor layer to the utmost.
To achieve these objects and other objects, a first semiconductor substrate manufacturing method provided by the invention includes a defective layer forming step of carrying out ion implantation to a predetermined depth from the surface of a base substrate made of a monocrystalline semiconductor to form a defective layer for detachment use and partitioning off a monocrystalline thin film layer at the surface of the base substrate, a semiconductor film forming step of forming a monocrystalline semiconductor film of a predetermined thickness on the monocrystalline thin film layer at the surface of the base substrate, a laminating step of laminating the base substrate at the surface of the monocrystalline semiconductor film to a supporting substrate, and a detaching step of detaching the base substrate laminated to the supporting substrate at the defective layer.
Because the thickness of the semiconductor layer can be adjusted by adjusting the thickness to which the monocrystalline semiconductor film is formed in the semiconductor film forming step, even when the monocrystalline thin film layer formed at the surface of the base substrate in the defective layer forming step is made extremely thin, the semiconductor layer can be made thick. Therefore, the energy of the ion implantation in the defective layer forming step can be made low, and contamination of the monocrystalline thin film layer by heavy metals and the like can be suppressed.
As a result, there are the highly valuable practical effects that, even when a thick semiconductor layer is to be formed on the supporting substrate, the SOI substrate can be manufactured with a simple process and cheaply and furthermore impurity contamination can be kept low.
A second manufacturing method provided by the invention includes a defective layer forming step of carrying out ion implantation to a predetermined depth from the surface of a base substrate made of a monocrystalline semiconductor to form a defective layer for detachment use so as to provide a monocrystalline thin film layer at the surface of the base substrate, a laminating step of laminating the base substrate at the surface of the monocrystalline thin film layer to a supporting substrate, a detaching step of detaching the base substrate laminated to the supporting substrate at the defective layer, and a semiconductor film forming step of forming a monocrystalline semiconductor layer of a predetermined thickness on the monocrystalline thin film layer on the surface of the supporting substrate.
In the second semiconductor substrate manufacturing method also, because the thickness of the semiconductor layer can be adjusted by adjusting the thickness to which the monocrystalline semiconductor film is formed in the semiconductor film forming step, even when the monocrystalline thin film layer formed at the surface of the base substrate in the defective layer forming step is made extremely thin, the semiconductor layer can be made thick. Therefore, the energy of the ion implantation in the defective layer forming step can be made low, and contamination of the monocrystalline thin film layer by heavy metals and the like can be suppressed.
As a result, there are the highly valuable practical effects that, even when a thick semiconductor layer is to be formed on the supporting substrate, the SOI substrate can be manufactured with a simple process and cheaply and furthermore impurity contamination can be kept low.
In the manufacturing methods described above, the ion implantation in the defective layer forming step may be carried out with an oxide film formed on the surface of the base substrate and the oxide film then removed after the formation of the defective layer. In this way, it is possible to prevent
Matsui Masaki
Ohshima Hisayoshi
Onoda Kunihiro
Yamauchi Shoichi
Denso Corporation
Lee Granvill
Pillsbury & Winthrop LLP
Smith Matthew
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