U.S. patent application number 10/799069 was filed with the patent office on 2004-09-09 for heating furnace and semiconductor wafer-holding jig assembly and process of manufacturing semiconductor devices.
Invention is credited to Takagi, Mikio.
Application Number | 20040175878 10/799069 |
Document ID | / |
Family ID | 19058657 |
Filed Date | 2004-09-09 |
United States Patent
Application |
20040175878 |
Kind Code |
A1 |
Takagi, Mikio |
September 9, 2004 |
Heating furnace and semiconductor wafer-holding jig assembly and
process of manufacturing semiconductor devices
Abstract
An assembly of heating furnace and semiconductor wafer-holding
jig. This assembly includes a furnace body made of refractory or
heat insulting material; a heater disposed around the inner side
surface of the furnace body; a reaction chamber which forms a
uniform heating zone; and a wafer-holding jig. The wafer-holding
jig is capable of holding the wafer and advancing and retracting
the wafer in the uniform heating region along the longitudinal
direction of the furnace body. The front surface of the
semiconductor wafer to be heat-treated is substantially in parallel
with the surface of the heater. The assembly of the invention can
be used in rapid thermal processing and the footprint of the
heating furnace can be reduced.
Inventors: |
Takagi, Mikio;
(Kawasaki-City, JP) |
Correspondence
Address: |
THOMAS, KAYDEN, HORSTEMEYER & RISLEY, LLP
100 GALLERIA PARKWAY, NW
STE 1750
ATLANTA
GA
30339-5948
US
|
Family ID: |
19058657 |
Appl. No.: |
10/799069 |
Filed: |
March 12, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10799069 |
Mar 12, 2004 |
|
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|
10202698 |
Jul 25, 2002 |
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Current U.S.
Class: |
438/200 |
Current CPC
Class: |
C30B 25/08 20130101;
C23C 16/46 20130101; C30B 25/12 20130101; C23C 16/4587 20130101;
H01L 21/67303 20130101; H01L 21/68707 20130101; H01L 21/67109
20130101; H01L 21/67346 20130101 |
Class at
Publication: |
438/200 |
International
Class: |
H01L 021/31 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 26, 2001 |
JP |
2001-225713 |
Claims
What is claimed is:
1. An assembly of heating furnace and semiconductor wafer-holding
jig, comprising: a furnace body made of refractory or heat
insulting material having at least one flat surface; a heater
disposed around the inner side surface of said furnace body; a
reaction chamber which forms a uniform heating zone; and a
wafer-holding jig capable of holding a semiconductor wafer and
advancing and retracting the semiconductor wafer in the uniform
heating zone along the longitudinal axes of the furnace body, the
wafer-holding jig arranged such that the front surface of the
semiconductor wafer is substantially in parallel with said flat
surface of said heater.
2. The assembly as claimed in claim 1, wherein said heating furnace
is a vertical heating furnace.
3. The assembly as claimed in claim 1, wherein said heating furnace
is a horizontal heating furnace.
4. The assembly as claimed in claim 1, further comprising a
plurality of thermal storage plates disposed in the uniform heating
zone, wherein the thermal storage plates are of the same size, or
are smaller than the semiconductor wafers, and are disposed
substantially in parallel with the semiconductor wafer or between
two semiconductor wafers.
5. A method of manufacturing a semiconductor device, comprising
heat-treating a semiconductor wafer by rapid thermal processing
using the assembly as claimed in claim 1.
6. A method of manufacturing a semiconductor device, comprising
heat-treating a semiconductor wafer by rapid thermal processing
using the assembly as claimed in claim 4.
7. A semiconductor wafer-holding jig used in a-heating furnace,
comprising: a gas introduction hollow conduit disposed along the
longitudinal direction of the heating furnace; and a wafer-holding
jig disposed on the front end of said gas introduction hollow
conduit, comprising a wafer-holding portion which includes an
ejection hole for ejecting a gas to the semiconductor wafer from
said gas introduction hollow conduit.
8. The semiconductor wafer-holding jig as claimed in claim 7, which
is used in a vertical heating furnace.
9. The semiconductor wafer-holding jig as claimed in claim 7, which
is used in a horizontal heating furnace.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an assembly of a hot
wall-heating furnace used in the process of manufacturing various
semiconductor devices; including the CVD process and diffusion
process, and a semiconductor wafer-holding jig. The present
invention also relates to a process of manufacturing semiconductor
devices using this assembly.
[0003] 2. Description of the Related Art
[0004] Semiconductor manufacturing apparatuses using a hot
wall-heating furnace are well known. For example, in the Conference
of Applied Physics, (No. 55, Nagoya, Japan, Sep. 19-22, 1994), it
is reported that, in rapid thermal annealing (RTA) , moving a wafer
between a low temperature zone and a high temperature zone,
disposed respectively at the top and bottom portion of a vertical
hot wall heating furnace, can obtain a better sheet resistance
distribution in the wafer surface than that by using an ordinary
RTA. It is also reported that in RTA, five wafers are heat-treated
at a temperature of 1000.degree. C. for 10 seconds to produce CMOS
devices by using the above-mentioned vertical heating furnace (3rd
International Rapid Thermal Processing conference, RTP '95. Aug.
30-Sep. 1, 1995, Amsterdam, Netherlands, THE EFFECTS OF RAPID
THERMAL PROCESSING ON QUARTER MICRON CMOS DEVICES, pp 101-103). It
is also reported that this type of furnace is suitable for use in
the reflow process (4.sup.th Int. Conf. On Advanced Thermal
Processing of Semiconductors-RTP, '96, 30-33), and in the annealing
of gigabit DRAM devices (4.sup.th Int. Conf., On Advanced Thermal
Processing of Semiconductors, RTP '96).
[0005] FIG. 1 shows the main structure of a vertical single wafer
heating furnace having excellent temperature distribution.
Referring to FIG. 1, 1 is a furnace body made of refractory or heat
insulating material. 2 is a heater. 3 is a reaction chamber made of
quartz. 4 is a gas introduction conduit opened at the top of the
reaction chamber 3 for feeding reaction gas from the bottom portion
of the furnace. 5 is a furnace floor plate. 6 is a lifting rod
which is elevated and rotated in the furnace body in the heat
treatment process. 7 is a wafer holding portion extended upwards
obliquely from the lifting rod 6. 8 is a wafer. 9 is a claw
extended horizontally from the wafer holding portion for holding
the back surface of the wafer. 10 is an O-ring. 11 is an exhaust
conduit opened at the bottom of the reaction chamber 3. By using a
heating furnace having such a structure, the temperature
distribution of the wafer 8 is influenced by the distance from the
heater 2, and thus the temperature at the center of the wafer is
high while the temperature in the peripheral portion is low.
[0006] In order to make the temperature distribution of the front
surface of the wafer uniform, the applicant of this application has
proposed a method that has been patented in the United States as
U.S. Pat. No. 6,159,873. According to the patented method, thermal
storage plates having substantially the same size of the wafer are
disposed in the heating furnace, and are preliminarily heated to a
heat-treating temperature, and then the wafer is positioned to the
proximity of the thermal storage plates. By using both the heat
from the heater and from the thermal storage plates, it is possible
to make temperature distribution of the front surface of the wafer
uniform and raise the temperature of the wafer rapidly. In the
article published in the Conference of Applied Physics, Spring,
1998, the effect of the thermal storage plates has been
investigated and studied by means of simulation by the inventors of
said U.S. patent.
[0007] Moreover, U.S. Pat. No. 6,159,873 disclosed several
embodiments of the use of thermal storage plates as heaters. In
FIG. 12 of the US patent, it is shown that the front surface of the
wafer is positioned in the direct proximity of the heater that is
mounted in the flat ceiling portion of the furnace. In this manner,
as the wafer and the heater are positioned close to each other, the
temperature distribution of the front surface of the wafer can be
significantly improved.
[0008] According to the method of the U.S. patent, since the wafer
is positioned in direct proximity of the heater mounted in the
ceiling portion of the furnace, the temperature distribution is
improved. However, because the section of the heating furnace is
circular in shape, the clean room footprint of the furnace is big.
As the building cost of a clean room for accommodating a heating
furnace for manufacturing semiconductor devices is high, it is
desirable to reduce the clean room footprint of the heating
furnace.
SUMMARY OF THE INVENTION
[0009] An object of the present invention is to provide an assembly
of a heating furnace and wafer-holding jig that can significantly
reduce the clean room footprint of the heating furnace.
[0010] Another object of this invention is to provide a process of
manufacturing semiconductor devices using the assembly of the
invention.
[0011] In the heat treatment of semiconductor wafers (hereinafter
wafer(s)), if the wafers are horizontally supported in a vertical
heating furnace, the footprint is larger than the surface area of
the wafers. Moreover, if the wafers are held upright in a
horizontal heating furnace, similarly, the footprint is larger than
the surface area of the wafers. In any case, the size of the
heating furnace becomes larger. In order to make the front surface
of the wafer be consistent with the longitudinal axes of the
furnace, i.e., the vertical axes of a vertical heating furnace or
the horizontal axes of a horizontal heating furnace, the
wafer-holding jig is usually assembled with the heating
furnace.
[0012] It has been found by the inventors that by changing the
sectional profile of the heating furnace in such a manner that the
front surface of the wafer is parallel to the inner side surface of
the furnace, the above objects can be attained.
[0013] Specifically, the assembly of heating furnace and
semiconductor wafer-holding jig of the invention includes a furnace
body made of refractory or heat insulting material; a heater
disposed around the inner side surface of the furnace body; a
reaction tube which forms a uniform heating zone; and a
wafer-holding jig capable of holding the wafer, and advancing and
retracting in the uniform heating zone along the longitudinal axes
of the furnace body. The assembly of the invention is characterized
in that the front surface of the wafer is held on the wafer-holding
jig in such a manner that the front surface is substantially in
parallel with the surface of the heater.
[0014] According to an aspect of the invention, the assembly can be
applied in a vertical heating furnace or a horizontal-heating
furnace.
[0015] According to another aspect of the invention, the assembly
can include a plurality of thermal storage plates disposed in the
uniform heating zone. The thermal storage plates are of the same
size, or are smaller than the wafers, and are disposed
substantially in parallel with one of the wafers or between two
wafers.
[0016] According to a further aspect of the invention, the assembly
of the invention can be used in rapid thermal processing (RTP)
including RTA (Rapid Thermal Annealing), RTO (Rapid Thermal
Oxidation), RTN (Rapid Thermal Nitriding), RTCVD (Rapid Thermal
Chemical Vapor Deposition), and RT-Wet Reflowing. When the assembly
of the invention is used in a RTA, the temperature of the furnace
is raised or lowered at a rate of 10-150.degree. C./sec and kept
for 0-20 seconds at the heat-treating temperature. Under the same
conditions above, the assembly can be used in RTO to form thin
oxide film, and in RTN to form nitride film on the silicon surface.
The assembly also can be used in atmosphere of CVD gas, under the
same conditions, to form a CVD film. The assembly can also be used
in high temperature steam to reflow a film of BPSG. By using the
assembly of the invention, RTP can be applied on 8-12 inch CVD
film.
[0017] According to a further aspect of the invention, the assembly
of the invention also includes a gas- introduction hollow conduit
disposed along the longitudinal axes of the heating furnace. The
gas-guiding hollow conduit is communicated with the wafer-holding
jig. The wafer-holding jig includes a wafer-holding portion having
an ejecting hole for ejecting a gas that is inert to the wafer from
the gas introduction hollow conduit.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The present invention can be more fully understood by
reading the subsequent detailed description in conjunction with the
preferred embodiments and references made to the accompanying
drawing, wherein:
[0019] FIG. 1 illustrates an embodiment of a vertical single wafer
hot wall heating furnace according to the prior art;
[0020] FIG. 2 is a cross-sectional view illustrating an embodiment
of an assembly of vertical heating furnace and vertically disposed
wafer-holding jig according to the present invention;
[0021] FIG. 3 is a vertical-sectional view of the furnace shown in
FIG. 2;
[0022] FIG. 4 is a cross-sectional view illustrating an embodiment
of an assembly of vertical heating furnace, wafer-holding jig and
thermal storage plate according to the present invention;
[0023] FIG. 5 is a sectional view taken from A-A of FIG. 4;
[0024] FIG. 6 illustrates an embodiment of an assembly of a
horizontal heating furnace and vertically disposed wafer-holding
jig, which is a sectional view taken from A-A of FIG. 7;
[0025] FIG. 7 is a sectional view taken from B-B of FIG. 6;
[0026] FIG. 8 illustrates an embodiment of the structure of the
claw portion of the wafer-holding jig, which is a sectional view
taken from C-C of FIG. 7;
[0027] FIG. 9 illustrates another embodiment of the structure of
the claw portion of the wafer-holding jig, which is a sectional
view taken from B-B of FIG. 7;
[0028] FIGS. 10a and 10b illustrate the wafer-holding jig which is
horizontally disposed in a horizontal heating furnace;
[0029] FIG. 10c is a schematic view showing the heating profile of
the wafer;
[0030] FIG. 11 is a schematic view of an assembly of a horizontal
heating furnace and a horizontally disposed wafer-holding jig;
[0031] FIG. 12 is a plan view of FIG. 11; and
[0032] FIG. 13 is a schematic view illustrating the section of the
frame shown in FIG. 11 and FIG. 12.
DETAILED DESCRIPTION OF THE INVENTION
[0033] Referring to FIGS. 2 and 3, it should be noted that the same
portions of the heating furnace as illustrated in FIG. 1 are given
the same reference numerals. As can be seen from FIG. 2 and FIG. 3,
wafer 8 is held upright in the vertical heating furnace. The heater
2 of the heating furnace is disposed around the inner side surface
of the furnace body 1 and is not arranged in a circular shape as in
a conventional heating furnace. The cross-sectional profile of
heater 2 is arranged in an oblong shape comprising a straight line
connected with a curved line, as can be seen in FIG. 2. As a
result, the uniformity of the temperature distribution of the front
surface of the wafers can be increased and the footprint of the
heating furnace is reduced. In these figures, w is the diameter of
the wafer, and when w equals 12 inches, L.sub.0 (length of the
reaction tube) equals 400 mm, L.sub.1 (maximum diameter of heater
2) equals 410 mm, L.sub.2 (minimum diameter of heater 2) equals 70
mm, t (minimum diameter of reaction tube) equals 50 mm, and T
(thickness of the furnace wall) equals 70 mm. Note that although
only one wafer is shown in FIG. 2, two wafers can be held in
parallel according to the present invention. It can be understood
from FIG. 2 that the products of d.times.D and D.times.D(D.sup.2)
respectively approximate to the footprint of the heating furnace
disclosed and a conventional furnace. Accordingly, the reduction
rate of the footprint according to the present invention can be
denoted by d/D, which is about 30-50%.
[0034] The structures as shown in FIG. 4 and FIG. 5 are
respectively a modified structure of FIG. 2 and FIG. 3 with the
addition of thermal storage plates 12 for simultaneously
heat-treating two wafers. That is to say the thermal storage plates
12 have nothing to do with the loading of the wafers 8 and are
disposed in the uniform heating zone of the heating furnace.
Moreover, similar to U.S. Pat. No. 6,159,873, the thermal storage
plates 12 are disposed between the two upright held wafers 8. Note
that the thermal storage plate 12 has the same size as the wafers
8. If the thermal storage plate 12 has a bigger size than the
wafers 8, then temperature non-uniformity will occur, and the
uniformity of temperature distribution can not be obtained. The
thermal storage plates 12 are held in the recessed portion 3a of
the upper reaction chamber 3. By using the heating furnace having a
structure as shown in FIG. 4 and FIG. 5, two wafers can be
heat-treated at same temperature distribution profile as described
in FIG. 1. Moreover, the footprint ratio corresponding to the
number of the wafers is two times of that of the heating furnace of
FIG. 2.
[0035] Referring now to FIG. 6 and FIG. 7, wafer 8 is held upright
in a horizontal heating furnace. The furnace body 1 and the heater
2 are divided into high temperature heating zone a, where reaction
occurs, and low temperature heating zone b, where wafer 8 is held
at low temperature prior to reaction. As shown in FIG. 7, reference
numeral 13 is an exhaust conduit, 14 is an lid for closing the
inlet of the furnace, and 20 is a perforated rectifying plate in
honeycomb shape for adjusting the gas flow in the reaction room.
The width between furnace bodies 1a and 1b of the horizontal
furnace is less than {fraction (1/2)} of a conventional furnace,
and thus the footprint is reduced.
[0036] The wafer holding jig 16 as shown in FIG. 7 comprises a
hollow rod 17, and a curved arm portion 19 mounted on the front end
of the hollow rod 17 for holding the wafer 8. The wafer holding jig
16 is driven by any driving means so that it can be advanced and
retracted in the furnace along the low temperature heating zone b
and high temperature heating zone a. 15 is a spacer. Actually, the
hollow rod 17 functions both as a wafer-moving jig and a gas
introduction conduit. The curved arm portion 19 is opened at an
angle of 120.degree. so as to hold the bottom portion of the wafer
8. There are three claws 19a, 19b formed on the curved arm portion
19 and protruded to the center of the wafer 8. The two claws 19a
are so disposed that the extended line of each claw 19a forms an
angle of 60 degree with respect to the vertical line. These two
claw portions 19a have the function of preventing the wafer 8 from
falling off. That is, the claws 19 can hold the peripheral portion
of the wafer 8 from its two sides, and the inner portion of the
claws is forked to nip the wafer 8 so as to prevent the wafer from
falling off. The claw 19b, however, holds the wafer 8 from-its
bottom portion along the vertical line. Reaction gas is flowed in
the bore of the hollow rod 17 to the reaction room. The holding of
the wafer 8 by the claws 19 will be described in more detail
hereinafter.
[0037] Referring to FIG. 8, an embodiment of the structure in which
the reaction gas is flowed in the claws 19a is shown. The claws 19a
hold the wafer 8 to prevent it from falling off. The claws 19 are
mounted on the front end of the hollow rod 17, and have a structure
that can hold the wafer 8 and eject reaction gas. As can be seen
from FIG. 8, a space 23 that communicates with the bore of the
hollow rod 17 is formed in the outer shell 21 of the claw 19a. The
upper two sides of the outer shell 21 are bent to form a reversed
U-shaped recessed portion 27. On the other hand, inside the outer
shell 21, a U-shaped inner member 22 is disposed and is engaged in
a portion of the outer shell 21. The U-shaped inner member 22 forms
a part of the recessed portion 27. The silicon of the wafer 8
adheres to the quartz of the claw 19a when they are heated to a
temperature of above 1000.degree. C. and sintering reaction occurs.
As long as they are in adhesion, the frictional force between them
becomes larger, which usually causes a risk of production of
particles. Moreover, when the completely adhered wafer 8 and outer
shell 21 and inner member 22 are separated, particles are produced.
However, according to the present invention, a clearance 23 is
formed between the U-shaped inner portion 22 and the outer shell
21. Thus, reaction gas flows in the space formed by the U-shaped
inner member 22, and escapes from the small clearance formed at the
contacting portion of the wafer 8 and the quartz. As a result, it
is possible to prevent the friction between the wafer 8 and the
claws, and thus prevent the production of particles. Moreover, as
reaction gas has a small specific heat, it is sufficiently
preheated to a high temperature in the furnace and ejected out from
the clearance 24, and thus the temperature distribution of the
wafer 8 is not influenced.
[0038] Referring to FIG. 9 now, a structure in which the gas is
ejected from the vertically formed claw 19b is shown. 25 is a room
for the flow of the reaction gas from the hollow rod 16, and
functions as an interior room of the communicated claws 19a. 26 is
an ejection hole for the flow of inert gas, ie., a gas that does
not react with the wafer, such as nitrogen gas.
[0039] The present invention can also be applied in a horizontal
heating furnace in which the wafers are horizontally held. Although
an embodiment is not shown, it can be easily understood by
rearranging the sides 1a, 1b of the furnace body 1 of FIG. 6 to be
in the upper and lower positions. FIG. 10 is an embodiment
illustrating the wafer holding jig used in this situation. As shown
in FIG. 10, a different wafer-holding jig from that shown in FIG. 7
is illustrated. That is, at the front end of the rod 32 that can be
advanced and retracted in the furnace, a U-shaped holding portion
30 is fixed. From the front end, eight pins 33 are protruded
wherein the four inside pins hold the wafer 8 from its bottom
portion. In the high temperature zone of the furnace, a holding
frame 31 is disposed and similarly, eight pins 34 are protruded
from the holding frame 31. After the holding portion 30 is moved to
the upper side of the holding frame 31, wafer 8 is connected with
pins 34 and then descends. After that, the holding portion 30 is
retracted.
[0040] Referring to FIG. 11, in a horizontal furnace in which two
wafers are horizontally held, when the wafers are held on one
level, the occupied space is small, and by holding the wafers on
multi-levels, the occupied space can be further reduced. In this
case, the wafer-holding jig (not shown) is so designed that its
upper and lower forks can hold respectively one wafer, and the
wafers 8 can be held in an upper rack and a lower rack
respectively. FIG. 11 also illustrates another method for the
prevention of the sintering of wafer and quartz. Two wafers are
held in a wafer rack 41 by a wafer-holding jig (not shown). Wafer
18 is held from its bottom portion by 4 claws 19c which are 90
degree separated from the wafer's center. Claws 19c are fixed on
frame 42, which is short when viewing from the plan view. The frame
42 holds the flat surface 3a of the quartz reaction chamber 3 via a
base (not shown). A gas introduction conduit is extended from the
inlet of the quartz reaction gas chamber 3 to the zone of the frame
42 of the furnace, and the gas for preventing the sintering is
ejected from an ejection hole 19c opened at the front end of the
claw 19c. Referring to FIG. 13, the tube 41, which constitutes the
frame, can eject gqs from the ejecting hole 19c and thus lift the
wafer 8 slightly, so that sintering can be prevented.
[0041] Referring to FIG. 10c now, when a silicon wafer is heated by
using the furnace of the invention and the high temperature section
is below 700.degree. C., the silicon wafer can be directly placed
in the high temperature section for heating. However, if the high
temperature section is higher than 800.degree. C., it is preferably
to place the wafer first in a uniform heating section and
preliminarily heated, and then rapidly moved to the high
temperature section for a rapid heating so as to reduce the stress
that may be occurred in the wafer.
[0042] When a horizontal furnace as shown in FIG. 7 and FIG. 11 is
used, it is also possible to follow the heating profile as
illustrated in FIG. 10c. That is, the wafer can be first placed in
a low temperature section for uniform heating, and then be moved to
high temperature section for rapid heating.
[0043] As described above, by using the present invention, the
temperature distribution of the wafers can be uniformly maintained,
and the cost of the investment of the semiconductor manufacturing
equipment can be saved.
* * * * *