Method and apparatus for controlling rise and fall of...

Single-crystal – oriented-crystal – and epitaxy growth processes; – Forming from vapor or gaseous state – With decomposition of a precursor

Reexamination Certificate

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C117S086000, C117S089000, C117S102000, C117S107000

Reexamination Certificate

active

06461428

ABSTRACT:

BACKGROUND OF INVENTION
The present invention relates to a method and an apparatus for controlling the rise and fall of the temperature in a semiconductor substrate including as a silicon wafer when such semiconductor substrate is being subjected to treatments such as oxidization, diffusion or chemical vapor deposition.
Further, the present invention relates to a susceptor in a gas phase thin film growth apparatus and a gas phase thin film growth apparatus using such susceptor and more particularly to a susceptor which is capable of minimizing contamination of the semiconductor substrate caused by metal impurities at the time of effecting an air phase growth of a thin film and an apparatus using such susceptor.
The semiconductor substrate has a wide range of temperature rise/fall characteristics depending on materials, thickness and physical properties and, in other words, differs in the rate of temperature rise/fall and the in-plane temperature distribution.
Particularly, silicon wafers have different temperature rise/fall characteristics depending on the concentration of dopants including boron, phosphor and antimony.
Conventionally, the control of rising and falling semiconductor temperature at the time of oxidation, diffusion and chemical vapor deposition is done by feeding semiconductor substrates into a reactor set at an actual operating temperature, measuring the temperature of said semiconductor substrates to obtain temperature rise/fall characteristics of the respective semiconductor substrates, and then, writing respective temperature control programs on the basis of the thus obtained data for the temperature rise and fall control and using only a reactor installed with a specific temperature control program which suits a semiconductor having a specific temperature rising/falling characteristic.
According to the conventional method of temperature rise/fall control of the semiconductor substrate, however, a problem that a semiconductor substrate is subjected to a temperature rise/fall control on the basis of a specific temperature control program suited to a semiconductor substrate having a specific temperature rise/fall characteristic. If a wrong semiconductor substrate having a different temperature rise/fall characteristic is fed into the reactor to be heated on the basis of said specific temperature control program, a heat stress is exerted to said semiconductor substrate with the result that cracks can be formed in the semiconductor substrate leading to troubles such as damage to the components of the reactor, breakdown of the reactor, or the like. Such troubles are likely to cause production inefficiency and cost increase.
Therefore, the first object of the present invention is to provide a method and an apparatus for controlling the rise and fall of a semiconductor substrate which is free from any cracks in the semiconductor substrate even though the a semiconductor substrate having a different temperature rise/fall characteristic is fed into the reactor and the temperature is cause to rise and fall on the basis of the program install to the reactor.
Further, the gas phase thin film growth apparatus in which a thin film is gas phase grown on the semiconductor substrate such as a silicon wafer or the like has a structure as shown in FIG.
12
.
More specifically, the conventional gas phase thin film growth apparatus is composed of a cylindrical reactor
31
, a susceptor
32
provided in the lower inner part of said reactor
31
for holding a semiconductor substrate W such as a silicon wafer or the like, rotary drive means including a rotary shaft
33
and a motor (not shown) for rotating said susceptor
32
and a heater
34
for heating the semiconductor substrate W supported by said susceptor
34
. Further, there are a plurality of exhaust gas pipes
35
provided at the bottom of said reactor
31
to discharge a leftover reaction gas, said exhaust gas pipes
35
being connected to the exhaust gas control system (not shown).
On the other hand, the upper part of the reactor
31
is provided with a plurality of gas supply pipes
36
to allow a reaction gas such as a material gas for producing the thin film and a carrier gas therefor into the reactor
31
and a disc shaped inflow gas guiding plate
37
. Said admitted gas guiding plate
37
has a number of holes
37
a
therein to guide the gas flow.
Further, said susceptor
32
is disc-shaped and formed of a material such as carbon, silicon carbide, quartz or the like, with the upper surface thereof being formed with a seat recess for holding said semiconductor substrate therein as disclosed in Japanese Patent Application (Kokai) Publication No. 8-48595.
Further, while having said inflow gas guide plate
37
provided in the upper part of the reactor
31
so as to prevent the semiconductor substrate W from being contaminated by impurities such as whiled-up metal particles by suppressing an inflow of the atmosphere gas, said conventional gas phase thin film growth apparatus also has a cylindrical gas guiding member
8
so as to surround the lower area of a reverse side peripheral portion of said susceptor
2
.
Thus constructed, the susceptor
32
holding the wafer substrate W thereon is rotated at a predetermined revolution by a motor drive in said conventional gas phase thin film growth apparatus. At this time, the wafer substrate W is rotated and heated by the heater
34
to the predetermined temperature. Also at the same time, the reaction gases such as a material gas and a carrier gas therefore are allowed into said reactor
31
by way of a plurality of gas supply pipes
36
. With the reaction gases passing through said plurality of holes
37
a
in the inflow gas guide plate
37
, the gas flow rate distribution within the reactor
31
is made uniform. The thus uniformly distributed reaction gases are supplied onto the semiconductor substrate W held on the susceptor
32
to gas phase grow into a thin film.
In said gas phase thin film growth apparatus, the atmosphere gases (reaction gases) cause particles to be whirled up in turbulences, adherents on the inner wall of the reactor to be accumulated or the semiconductor substrate to be contaminated with metal impurities. Therefore, it is essential to see that such whirl up of the particles, accumulation of adherents on the inner wall of the reactor or contamination of the substrate is suppressed such that contamination of the semiconductor substrate from metal impurities is prevented for minimizing the formation of crystal flaw in the thin film formed on the semiconductor substrate.
For this purpose, said gas phase thin film growth apparatus is provided with the above mentioned inflow gas guide plate
37
in the upper part of the reactor and the cylindrical gas guiding member
38
to surround the lower area of the space around the susceptor.
As a result, the turbulence of the atmosphere gas (the reaction gas) in the upper and lower areas of the space beneath the susceptor
32
is suppressed, thus preventing the particles from whirling up and the semiconductor substrate from being contaminated by metal impurities.
In this connection, as shown in FIG.
13
and
FIG. 14
, the rotated susceptor causes a flow of the atmosphere gas flow (gas flow) to generate from the central area to the peripheral area of the susceptor
32
as shown in arrow on the reverse side of the susceptor
32
. In this connection, it is noted that
FIGS. 13 and 14
are fragmental sectional views of the peripheral area of the susceptor
32
;
FIG. 13
shows the gas deflector
38
is formed at the peripheral area of the susceptor
32
on the reverse side thereof whereas
FIG. 14
shows the gas deflector
38
is formed over the entire reverse side of the susceptor
32
.
The flow of said atmosphere gas (gas flow) is generated by the centrifugal force caused by the rotation of the susceptor
32
and the viscosity of the gas. Such gas flow is sucked from the lower peripheral area of the wall and from near the bottom of the reactor
31
to rise along the periphery of the rotary shaft
33
until flowing out

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