U.S. patent application number 09/842071 was filed with the patent office on 2001-08-23 for processing method for substrate.
Invention is credited to Ishii, Katsumi.
Application Number | 20010016307 09/842071 |
Document ID | / |
Family ID | 18200528 |
Filed Date | 2001-08-23 |
United States Patent
Application |
20010016307 |
Kind Code |
A1 |
Ishii, Katsumi |
August 23, 2001 |
Processing method for substrate
Abstract
A processing unit for a substrate has a vertical thermal
processing furnace 4 having a bottom and an opening 4a provided at
the bottom. A boat 3 holding substrates W in vertical multistairs
can be placed on a first lid 17, and the first lid 17 can open and
close the opening 4a of the vertical thermal processing furnace 4
with the boat 3 placed thereon. The processing unit also has a
boat-placing portion 19 on which the boat 3 and another boat 3 can
be placed and a boat conveying mechanism 21 for conveying the two
boats 3 alternatively between the boat-placing portion 19 and the
first lid 17. A second lid 18 hermetically closes the opening 4a of
the vertical thermal processing furnace 4 when the first lid 17
opens the opening 4a but no boat 3 passes through the opening 4a.
The processing unit can effectively reduce the undesirable
influence from the opening 4a when the first lid 17 is taken off
from the opening 4a and the boat 3 is conveyed out, and can also
reduce the wasted energy by preventing the fall of the temperature
in the interior of the thermal processing furnace 4.
Inventors: |
Ishii, Katsumi;
(Kanagawa-ken, JP) |
Correspondence
Address: |
Michael A. Makuch
SMITH, GAMBRELL & RUSSELL, LLP
1850 M Street, NW - Suite 800
Washington
DC
20036
US
|
Family ID: |
18200528 |
Appl. No.: |
09/842071 |
Filed: |
April 26, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09842071 |
Apr 26, 2001 |
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09321542 |
May 28, 1999 |
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6247245 |
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Current U.S.
Class: |
432/239 ;
118/724; 118/725; 414/147; 414/149; 414/937; 414/938; 432/124;
432/241 |
Current CPC
Class: |
H01L 21/67757 20130101;
H01L 21/67778 20130101; H01L 21/67769 20130101; Y10S 414/14
20130101; Y10S 414/138 20130101 |
Class at
Publication: |
432/239 ;
432/124; 432/241; 118/724; 118/725; 414/147; 414/149; 414/937;
414/938 |
International
Class: |
B65G 025/04; B65G
049/07 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 18, 1998 |
JP |
327568/1998 |
Claims
What is claimed is:
1. A processing unit comprising; a vertical thermal processing
furnace having a bottom and an opening provided at the bottom, a
first lid on which a boat holding substrates in vertical
multistairs can be placed and which can open and close the opening
of the vertical thermal processing furnace with the boat placed
thereon, a boat-placing portion on which the boat and another boat
can be placed, a boat conveying mechanism for conveying the two
boats alternatively between the boat-placing portion and the first
lid, and a second lid for hermetically closing the opening of the
vertical thermal processing furnace when the first lid opens the
opening but no boat passes through the opening.
2. A processing unit according to claim 1, wherein: the second lid
is a shutter which can be moved vertically and horizontally with
respect to an outside surface of the opening of the vertical
thermal processing furnace to open and close the opening.
3. A processing unit according to claim 1, further comprising: a
carrier-placing portion on which a carrier housing the substrates
can be placed, and a transferring mechanism for transferring the
substrates between the carrier placed on the carrier-placing
portion and the boat placed on the boat-placing portion.
4. A processing unit according to claim 3, wherein: the
transferring mechanism is retractable in such a manner that the
transferring mechanism does not interfere with the boat when the
boat is conveyed by the boat conveying mechanism.
5. A processing unit according to claim 3, further comprising; a
notch aligning mechanism arranged along a vertical central line of
the carrier-placing portion for aligning notches provided at the
substrates.
6. A processing unit according to claim 1, wherein: the boat
conveying mechanism includes; a first arm which has a rotational
axis and a distal end and which can be vertically elevated and
horizontally rotated around the rotational axis, and a second arm
which is supported at the distal end in such a manner that the
second arm can horizontally rotate around the distal end and which
can vertically hold the boat and convey the boat in such a manner
that a center of the boat passes over the rotational axis of the
first arm, and the boat conveying mechanism can convey the boat in
a radial direction with respect to the rotational axis of the first
arm by synchronously rotating the first arm and the second arm.
7. A processing unit according to claim 6, wherein: the
transference mechanism is movable vertically above the boat
conveying mechanism.
8. A processing unit according to claim 1, further comprising: a
ventilating unit disposed adjacent the boat-placing portion for
making a clean gas flow.
9. A processing unit according to claim 8, wherein: the
boat-placing portion has a first placing portion and a second
placing portion arranged between the first placing portion and the
first lid, and the boat conveying mechanism is operable to convey
the boat from the first placing portion to the second placing
portion, from the second placing portion to the first lid, and from
the first lid to the first placing portion in such a manner that
the boat passes under lee of the second placing portion with
respect to the clean gas flow made by the ventilating unit.
10. A processing method for a substrate by using a processing unit
for the substrate comprising: a vertical thermal processing furnace
having a bottom and an opening provided at the bottom, a first lid
on which a boat holding substrates in vertical multistairs can be
placed and which can open and close the opening of the vertical
thermal processing furnace with the boat placed thereon, a
boat-placing portion having a first placing portion and a second
placing portion arranged between the first placing portion and the
first lid, a second lid for hermetically closing the opening of the
vertical thermal processing furnace when the first lid opens the
opening but no boat passes through the opening, a carrier-placing
portion on which a carrier housing the substrates can be placed, a
transferring mechanism for transferring the substrates between the
carrier placed on the carrier-placing portion and the boat placed
on the boat-placing portion, a ventilating unit disposed adjacent
the boat-placing portion for making a clean gas flow, and a boat
conveying mechanism for conveying the boat from the first placing
portion to the second placing portion, from the second placing
portion to the first lid, and from the first lid to the first
placing portion in such a manner that the boat passes under lee of
the second placing portion with respect to the clean gas flow made
by the ventilating unit, said method comprising the steps of:
conveying a first boat from the first portion to the second portion
by the boat conveying mechanism, conveying a second boat from the
first lid to the first portion by the boat conveying mechanism in
such a manner that the second boat passes under the lee of the
second placing portion with respect to the clean gas flow made by
the ventilating unit, and conveying the first boat from the second
portion to the first lid by the boat conveying mechanism.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a processing unit for a substrate
and a processing method for a substrate.
[0003] 2. Disclosure of the prior art
[0004] Processes for manufacturing semiconductor devices include
steps in which semiconductors as substrates undergo processes such
as oxidation, diffusion, CVD (Chemical Vapor Deposition) or the
like. Vertical thermal processing units are often used for
conducting the various processes. A conventional vertical thermal
processing unit comprises: an carrier-transferring area where an
operator or an automatic conveying mechanism holds and conveys a
carrier housing semiconductor wafers, and a loading area where
semiconductor wafers in the carrier are transferred to a boat as a
holder for a thermal processing which is then loaded into or
unloaded from a thermal processing furnace.
[0005] In such vertical thermal processing units, it is preferable
for a partition (bulkhead) to be provided between the
carrier-transferring area which is exposed to the atmosphere and
the loading area. The partition allows the loading area to remain
clean and prevents a natural oxidation film from forming on the
semiconductor wafers. The loading area should also be preferably
filled with an inert gas such as nitrogen. A closed-type carrier,
whose entrance for semiconductor wafers can be hermetically closed
by a lid, should also be preferably used in the vertical thermal
processing unit in order to prevent the semiconductor wafers from
being contaminated with particles.
[0006] A carrier-placing portion having an opening is arranged at
the partition between the carrier-transferring area and the loading
area. The opening is adapted to become in contact with the carrier
on the side of the carrier-transferring area. A door is provided at
the opening on the side of the loading area to open and close it.
When processing the semiconductor wafers, the lid of the carrier is
aligned to be in contact with the carrier-placing portion, and the
door and the lid are opened to communicate the interior of the
carrier with the loading area. The semiconductor wafers are then
conveyed from the interior of the carrier to the boat in the
loading area via the opening. The boat is then loaded in the
thermal processing furnace to perform the prescribed processes on
the semiconductor wafers.
[0007] Furthermore, two boats are used as below. One boat of them
is placed on the lid which can be vertically elevated to open and
close the opening of the thermal processing furnace. The boat is
conveyed into the thermal processing furnace. While the opening of
the furnace is hermetically closed with the lid and the
semiconductor wafers in the boat undergo the thermal processing,
other the semiconductor wafers are transferred to the other boat.
This improves the throughput of the vertical thermal processing
unit.
[0008] Vertical thermal processing units for semiconductor wafers
having large, for example 300 mm diameters need thermal processing
furnaces having large capacities and large openings. Thus, after
the thermal processing, considerable heat in the furnace may leak
from the opening of the furnace into the loading area while the
opening of the furnace is opened, the boat in the furnace is
conveyed out, the next boat is conveyed into the furnace and the
opening of the furnace is closed with the lid. This may raise the
temperature of the loading area and influence instruments in the
loading area. In addition, the wasted energy may be so much because
the interior of the thermal processing furnace has to be maintained
above the predetermined temperature.
[0009] The width, the depth and the height of the vertical thermal
processing unit are increased accompanying the increase of the
diameter of the semiconductor wafer, for example to 300 mm. The
space of the floor and the height of the ceiling are also increased
for arranging the vertical thermal processing unit. These lead to
the increase of the costs for manufacturing and maintaining of the
vertical thermal processing unit. Therefore, there is a requirement
that the vertical thermal processing unit be miniaturized as much
as possible.
[0010] In order to improve the ability to process the semiconductor
wafers with the vertical thermal processing unit, it is desirable
that the boat-placing portion is disposed in the loading area for
placing one boat to which semiconductor wafers are transferred
while the thermal processing is conducted to the other boat, that
the transferring mechanism is disposed in the loading area for
transferring the semiconductor wafers between the boat on the
boat-placing portion and the carrier at the carrier-placing portion
and that the boat-conveying mechanism is disposed in the loading
area for conveying the boat between the boat-placing portion and
the lid. Having the trace of the boat and the occupying space of
the conveying mechanism overlap is effective in miniaturizing the
vertical thermal processing unit. However, in that case, there is
an undesirable possibility that the boat and the transferring
mechanism interference with each other.
[0011] In addition, the boat before the thermal processing may be
under the lee of the other boat after the thermal processing while
the two boats are conveyed between the boat-placing portion and the
lid respectively. In that case, the semiconductor wafers in the
boat before the thermal processing may be contaminated with
particles or gases coming from the other boat after the thermal
processing.
SUMMARY OF THE INVENTION
[0012] Therefore, the object of this invention is to provide a
vertical thermal processing unit, which can reduce the undesirable
influence caused by the heat leaking from the opening of the
furnaces when the lid is taken off from the opening and the boat
after the thermal processing is conveyed out.
[0013] Another object of this invention is to improve the ability
to process the substrates, by making the trace of the boat and the
occupying space of the transferring mechanism of the substrates
overlap and by laterally evacuating the transferring mechanism from
the trace of the boat when the boat is conveyed, in order to
prevent the interference of the boat and the transferring
mechanism.
[0014] Another object of this invention is to achieve the
miniaturization of the unit by arranging a notch aligning mechanism
along a vertical central line of the carrier-placing portion and by
reducing the width and the depth thereof without increasing the
height thereof.
[0015] Another object of this invention is to provide a boat
conveying method where the contamination of the substrates is
restricted when the boat is conveyed.
[0016] To achieve the above objects, this invention is
characterized by a feature wherein a processing unit for a
substrate comprises: a vertical thermal processing furnace having a
bottom and an opening provided at the bottom, a first lid on which
a boat holding substrates in vertical multistairs can be placed and
which can open and close the opening of the vertical thermal
processing furnace with the boat placed thereon, a boat-placing
portion on which the boat and another boat can be placed, a boat
conveying mechanism for conveying the two boats alternatively
between the boat-placing portion and the first lid, and a second
lid for hermetically closing the opening of the vertical thermal
processing furnace when the first lid opens the opening but no boat
passes through the opening.
[0017] According to the feature, the processing unit can
effectively reduce the undesirable influence from the opening when
the first lid is taken off from the opening and the boat is
conveyed out, and can also reduce the wasted energy by preventing
the fall of the temperature in the interior of the thermal
processing furnace.
[0018] Preferably, the second lid is a shutter which can be moved
vertically and horizontally with respect to an outside surface of
the opening of the vertical thermal processing furnace to open and
close the opening.
[0019] Preferably, the processing unit further comprises: a
carrier-placing portion on which a carrier housing the substrates
can be placed, and a transferring mechanism for transferring the
substrates between the carrier placed on the carrier-placing
portion and the boat placed on the boat-placing portion. In that
case, the transference mechanism is preferably retractable in such
a manner that the transferring mechanism does not interfere with
the boat when the boat is conveyed by the boat conveying mechanism.
In that case, the processing unit can be suitably miniaturized.
[0020] Preferably, a notch aligning mechanism is arranged along a
vertical central line of the carrier-placing portion for aligning
notches provided at the substrates. In that case, the width, the
depth and the height of the processing unit can be effectively
reduced, so that the time for transferring the substrates can be
substantially reduced.
[0021] Preferably, the boat conveying mechanism includes; a first
arm which has a rotational axis and a distal end and which can be
vertically elevated and horizontally rotated around the rotational
axis, and a second arm which is supported at the distal end in such
a manner that the second arm can horizontally rotate around the
distal end and which can vertically hold the boat and convey the
boat in such a manner that a center of the boat passes over the
rotational axis of the first arm, and the boat conveying mechanism
can convey the boat in a radial direction with respect to the
rotational axis of the first arm by synchronously rotating the
first arm and the second arm. In that case, the space for conveying
the boat can be minimized, so that the width and the depth of the
processing unit can be substantially reduced.
[0022] Preferably, the transferring mechanism is movable vertically
above the boat conveying mechanism.
[0023] Preferably, a ventilating unit is disposed adjacent the
boat-placing portion for making a clean gas flow. In that case, the
boat-placing portion has preferably a first placing portion and a
second placing portion arranged between the first placing portion
and the first lid, and the boat conveying mechanism is also
preferably operable to convey the boat from the first placing
portion to the second placing portion, from the second placing
portion to the first lid, and from the first lid to the first
placing portion in such a manner that the boat passes under lee of
the second placing portion with respect to the clean gas flow made
by the ventilating unit.
[0024] In addition, this invention is characterized by a feature
wherein a processing method for a substrate by using a processing
unit for the substrate comprising: a vertical thermal processing
furnace having a bottom and an opening provided at the bottom, a
first lid on which a boat holding substrates in vertical
multistairs can be placed and which can open and close the opening
of the vertical thermal processing furnace with the boat placed
thereon, a boat-placing portion having a first placing portion and
a second placing portion arranged between the first placing portion
and the first lid, a second lid for hermetically closing the
opening of the vertical thermal processing furnace when the first
lid opens the opening but no boat passes through the opening, a
carrier-placing portion on which a carrier housing the substrates
can be placed, a transferring mechanism for transferring the
substrates between the carrier placed on the carrier-placing
portion and the boat placed on the boat-placing portion, a
ventilating unit disposed adjacent the boat-placing portion for
making a clean gas flow, and a boat conveying mechanism for
conveying the boat from the first placing portion to the second
placing portion, from the second placing portion to the first lid,
and from the first lid to the first placing portion in such a
manner that the boat passes under lee of the second placing portion
with respect to the clean gas flow made by the ventilating unit,
said method comprises the steps of: conveying a first boat from the
first portion to the second portion by the boat conveying
mechanism, conveying a second boat from the first lid to the first
portion by the boat conveying mechanism in such a manner that the
second boat passes under the lee of the second placing portion with
respect to the clean gas flow made by the ventilating unit, and
conveying the first boat from the second portion to the first lid
by the boat conveying mechanism.
[0025] According to the feature, the contamination of the
substrates in the boat before the thermal processing is prevented
when the boat is conveyed because the boat does not pass under the
lee of the other boat after the thermal processing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIG. 1 is a schematic perspective view of an embodiment of
the vertical thermal processing unit of the invention;
[0027] FIG. 2 is a schematic plan view of the vertical thermal
processing unit in FIG. 1;
[0028] FIG. 3 is a schematic vertical sectional view of the
vertical thermal processing unit in FIG. 1;
[0029] FIG. 4 is a schematic front view of the carrier-placing
portion and the notch aligning mechanism in FIG. 1;
[0030] FIG. 5 is a schematic perspective view of the boat conveying
mechanism in FIG. 1;
[0031] FIG. 6 is a schematic plan view showing a way for conveying
the boats.
[0032] FIG. 7 is a schematic perspective view of another embodiment
of the vertical thermal processing unit of the invention;
[0033] FIG. 8 is a schematic plan view of the vertical thermal
processing unit in FIG. 7;
[0034] FIG. 9 is a schematic side view of the transferring
mechanism in FIG. 7;
[0035] FIG. 10 is an explanatory view showing an operation of the
transferring mechanism.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0036] Embodiments of the invention will now be described in more
detail with reference to FIGS. 1 to 10.
[0037] FIG. 1 schematically shows an embodiment of the vertical
thermal processing unit of the invention. FIG. 2 is a schematic
plan view of the vertical thermal processing unit in FIG. 1. FIG. 3
schematically shows a vertical section of the vertical thermal
processing unit in FIG. 1. FIG. 4 is a schematic front view of the
carrier-placing portion and the notch aligning mechanism in FIG. 1.
FIG. 5 is a schematic perspective view of the boat conveying
mechanism in FIG. 1. FIG. 6 is a schematic plan view showing a way
for conveying the boats.
[0038] In these figures, a numeral sign 1 designates a housing
forming outside walls of the vertical thermal processing unit
disposed in a clean room. The interior of the housing 1 is divided
by a partition (bulkhead) 5 into a carrier-transferring area Sa
into and from which carriers 2 are conveyed and in which the
carries 2 are kept, and a loading area Sb where semiconductor
wafers W (substrates to be processed) in the carriers 2 are
transferred to boats 3 which are loaded into or unloaded from a
vertical type thermal processing furnace 4.
[0039] As shown in FIGS. 1 and 2, an entrance 6 is provided in
front of the housing 1 for introducing and discharging the carriers
2 by an operator or an automatic conveying robot. As shown in FIGS.
2 and 3, the entrance 6 is provided with a door 7 which can move
vertically to open and close the entrance 6. A stage 8 is provided
near the entrance 6 in the carrier-transferring area Sa for placing
the carrier 2 thereon. As shown in FIGS. 1 and 3, a sensor
mechanism 9 is provided at the rear portion of the stage 8 for
opening a lid (not shown) of the carrier 2 and detecting positions
of and the number of the semiconductor wafers W. As shown in FIGS.
1 to 3, shelf-like storing sections 10 are formed above the stage 8
and near the upper portion of the partition 5 for storing a
plurality of the carriers 2.
[0040] As shown in FIG. 3, plural, for example two carrier-placing
portions (transfer stages) 11 are provided in vertically spaced
positions on the side of the partition 5 as tables for placing the
carriers 2 thereon for transferring the semiconductor wafers. Thus,
the throughput of the processing unit can be improved as one
carrier 2 can be exchanged at one carrier-placing portion while the
semiconductor wafers W are transferred to another carrier 2 at the
other carrier-placing portion. A carrier transference mechanism 12
is arranged in the carrier-transferring area Sa for transferring
the carriers 2 to and from the stage 8, the storing sections 10 and
the carrier placing portions 11.
[0041] As shown in FIG. 2, the carrier transference mechanism 12
comprises: an elevating arm 12b which can be moved vertically by an
elevating mechanism 12a provided on a side of the
carrier-transferring area Sa, and a transferring arm 12c mounted on
the elevating arm 12b for supporting the bottom of the carrier 2 to
horizontally transfer the carrier 2.
[0042] The carrier 2 is a so-called closed type, which can house a
number of, for example 13 or 25 semiconductor wafers W and which
can be hermetically closed by the lid (not shown). The carrier 2
comprises a portable plastic container for housing and holding
semiconductor wafers W in multistairs in horizontal attitude and in
vertically spaced relation by a prescribed pitch. The diameter of
the semiconductor wafer W is for example 300 mm. The lid (not
shown) is removably attached at the wafer-entrance formed in front
of the carrier 2 in such a manner that the lid can sealingly close
the wafer-entrance.
[0043] A clean atmospheric air, which has passed through filters
(not shown), is supplied into the carrier-transferring area Sa, so
that the carrier-transferring area Sa is filled with the clean
atmospheric air. On the other hand, a clean atmospheric air is also
supplied into the loading area Sb, so that the loading area Sb is
filled with the clean atmospheric air, or an inert gas such as
nitrogen (N.sub.2) is supplied into the loading area S2, so that
the loading area Sb is filled with the inert gas. As shown in FIG.
1, the partition 5 has two, upper and lower openings 13, with each
of which the carrier 2 is adapted to come into contact on the side
of the carrier-transferring area Sa. The openings 13 match with the
carrier-placing portions 11 respectively. Each opening 13 is
provided with a lid 14 for opening and closing the opening 13. The
opening 13 is formed in such a manner that the size of the opening
13 is substantially the same as that of the wafer-entrance of the
carrier 2, so that semiconductor wafers W can be transferred into
and from the carrier 2 through the opening 13 and the
wafer-entrance.
[0044] Each door 14 is provided with a lid opening-closing
mechanism (not shown) for opening and closing the lid of the
carrier 2. Each door 14 is also connected with a door
opening-closing mechanism (not shown) for opening and closing the
door 14 on the side of the loading area Sb. The door
opening-closing mechanism is adapted to move the door 14 and the
lid toward the side of the loading area Sb and further move
(evacuate) them upward or downward not to disturb the transference
of the semi conductor wafers W. As shown in FIG. 3, a notch
aligning mechanism 15 is arranged below the carrier-placing
portions 11 and along a vertical central line of the
carrier-placing portion 11 for aligning notches (cut portions)
provided at peripheries of the semiconductor wafers W i.e. for
aligning the crystalline directions of the semiconductor wafers W.
The notch aligning mechanism 15 has an opening on the side of the
loading area Sa. The notch aligning mechanism 15 is adapted to
align the notches of the semiconductor wafers W transferred from
the carrier 2 on the carrier-placing portion 11 by the transferring
mechanism 22.
[0045] The notch aligning mechanism 15 has two apparatus in
vertically spaced positions, each apparatus of which can align the
two notches of the two semiconductor wafers W. Thus, the throughput
of the processing unit can be improved as one apparatus can
transfer back the aligned semiconductor wafers W to the boat 3
while the other apparatus aligns other semiconductor wafers W. The
apparatus may be adapted to align plural, for example 3 or 5
semiconductor wafers W at a time. The central line of the
semiconductor wafer W being aligned by the notch aligning mechanism
15 is adapted to coincide with the central line 16 of the
semiconductor wafer W in the carrier 2 placed on the
carrier-placing portion 11. Thus, the width, the depth and the
height of the processing unit can be effectively reduced, so that
the time for transferring the semiconductor wafers can be
substantially reduced.
[0046] The thermal processing furnace 4 is disposed in a rear and
upper portion in the loading area Sb. The thermal processing
furnace 4 has a furnace opening 4a in the bottom thereof. A lid 17
is provided below the furnace 4. The lid 17 is adapted to be
vertically moved by an elevating mechanism (not shown) for loading
a boat 3 into and unloading it from the furnace 4 and for opening
and closing the furnace opening 4a. The boat 3, which can hold a
large number of, for example 100 or 150 semiconductor wafers W in
vertical equally spaced multistairs, is adapted to be placed on the
lid 17. The boat 3 is made of crystal or the like. The thermal
processing furnace 4 is provided with a shutter 18 at the furnace
opening 4a for closing the furnace opening 4a while the lid 17 is
taken off and the boat 3 is unloaded after the thermal processing.
The shutter 18 is adapted to horizontally pivot to open and close
the furnace opening 4a. A shutter driving mechanism 18a is provided
to make the shutter 18 pivot.
[0047] As shown in FIG. 2, a boat-placing portion (boat stage) 19
is disposed adjacently in a side region of the loading area Sb for
placing the boat 3 thereon when transferring semiconductor wafers W
into and from the boat 3. The boat-placing portion 19 has a first
placing portion 19a and a second placing portion 19b arranged
between the first placing portion 19a and the first lid 17. A
ventilating unit 20 is disposed adjacent the boat-placing portion
19 for cleaning the circulation gas (the clean atmospheric air or
the inert gas) in the loading area Sb via filters and making a
clean gas flow therefrom.
[0048] A boat-conveying mechanism 21 is arranged between the
carrier-placing portion 11 and the thermal processing furnace 4 in
the lower portion in the loading area Sb for conveying the boat 3
between the boat-placing portions 19 and the lid 17. Specifically,
the boat-conveying mechanism 21 is arranged for conveying the boat
3 between the first placing portion 19a or the second placing
portion 19b and the lowered lid 17, and between the first placing
portion 19a and the second placing portion 19b.
[0049] A transferring mechanism 22 is arranged above the
boat-conveying mechanism 21 for transferring semiconductor wafers W
between the carrier 2 on the carrier-placing portion 11 and the
boat 3 on the boat-placing portion 19, specifically between the
carrier 2 on the carrier-placing portion 11 and the notch aligning
mechanism 15, between the notch aligning mechanism 15 and the boat
3 on the first placing portion 19a of the boat-placing portion 19,
and between the boat 3 after the thermal processing on the first
placing portion 19a and the vacant carrier 2 on the carrier-placing
portion 11.
[0050] As shown in FIG. 2, the boat conveying mechanism 21 has an
arm which can support one boat 3 vertically and move (expands and
contracts) horizontally. Specifically, as shown in FIG. 5, the boat
conveying mechanism 21 has a first arm 21a which has a rotational
axis and a distal end and which can be elevated and horizontally
rotated around the rotational axis. The boat conveying mechanism 21
also has a C-shaped support arm 21b which is supported at the
distal end of the first arm 21a in such a manner that the support
arm 21b can horizontally rotate around the distal end. The C-shaped
support arm 21b forms an opening portion 21c whose center is
designed to pass the rotational axis of the first arm 21a and which
holds the boat 3 vertically. That is, a center of the boat can pass
over the rotational axis of the first arm 21a. Thus, the boat 3 can
be conveyed in a radial direction (a horizontal linear direction)
with respect to the rotational axis of the first arm 21a by
synchronously rotating the first arm 21a and the support arm 21b.
Therefore, the area for conveying the boat 3 can be minimized as
much as possible, so that the width and the depth of the processing
unit can be reduced.
[0051] The boat conveying mechanism 21 can move as shown by arrows
in FIG. 5. The boat conveying mechanism 21 conveys the boat 3 as
shown by arrows in FIG. 6. Specifically, the boat conveying
mechanism 21 conveys one boat 3 before the thermal processing
waiting on the first placing portion 19a to the second placing
portion 19b ({circle over (1)}). Then the boat conveying mechanism
21 conveys the other boat 3 after the thermal processing from the
first lid 17 to the first placing portion 19a({circle over (2)}).
Then, the boat conveying mechanism 21 conveys the boat 3 before the
thermal processing on the second placing portion 19b onto the lid
17 ({circle over (3)}). As shown in FIG. 6, the boat 3 after the
thermal processing can pass under lee of the second placing portion
19b with respect to the clean gas flow made by the ventilating unit
20. Thus, the boat 3 before the thermal processing never passes
under lee of the other boat 3 after the thermal processing.
Therefore, the semiconductor wafers W in the boat 3 before the
thermal processing are prevented from being contaminated by
particles or gases coming from the boat 3 after the thermal
processing when the boats 3 are conveyed.
[0052] As shown in FIG. 2, a transferring mechanism 22 has a base
stage 22a which can horizontally rotate around a rotational axis
and a support arm 22b provided on the base stage 22a which can move
forward and backward and which has plural, for example 2 or 5 thin
fork-like plates for supporting semiconductor wafers. The
transferring mechanism 22 can laterally retract (evacuate) from the
operating position A shown as an imaginary line in FIG. 2 into the
evacuating position B shown as a real line in the same figure by
means of an pivoting arm 23. A proximal end portion of the pivoting
arm 23 is connected with an elevating mechanism (not shown)
provided in the other side region of the loading area Sb. Thus, the
transferring mechanism 22 can move vertically. A lower protrusion
22c of the base stage 22a can be accommodated in the opening
portion 21c of the support arm 21b of the boat conveying mechanism
21 being in a lowered waiting state when the transferring mechanism
22 is lowered at the lowest position. Thus, the interference of the
transferring mechanism 22 with the boat conveying mechanism 21 is
prevented, and the elevating stroke of the transferring mechanism
22 is set in the smaller area.
[0053] Next, the operation of the described vertical thermal
processing unit is explained as below. The conveying method of the
boat is also explained together. When a carrier 2 is placed on the
stage 8 through the entrance 6, the sensor mechanism 9 detects the
placing state of the carrier 2. Then, the lid of the carrier 2 is
opened, and the sensor mechanism 9 detects positions of and the
number of the semiconductor wafers W in the carrier 2. Then, the
lid of the carrier 2 is closed again, and the carrier 2 is conveyed
into the keeping portions 10 by means of the carrier transference
mechanism 12.
[0054] Then, a carrier 2 stored in the keeping portion 10 is
conveyed onto the carrier-placing portion 11 at a suitable time by
means of the carrier transference mechanism 12. After the lid of
the carrier 2 on the carrier-placing portion 11 and the door 14 of
the opening 13 of the partition 5 are opened, the transferring
mechanism 22 takes out semiconductor wafers W from the carrier 2.
Then, the transferring mechanism 22 transfers them successively
into a vacant boat 3 placed on the first placing portion 19a of the
boat-placing portion 19 via the notch aligning mechanism 15. While
the semiconductor wafers W are transferred, the boat conveying
mechanism 21 is lowered to evacuate from the transferring mechanism
22, so that the interference of the boat conveying mechanism 21 and
the transferring mechanism 22 is prevented. As the notch aligning
mechanism 15 is arranged on the central line 16 of the
carrier-placing portion 11, the width of the vertical thermal
processing unit can be reduced, so that the processing unit can be
miniaturized. In addition, the time for transferring the
semiconductor wafers can be reduced, so that the throughput of the
processing unit can be substantially improved.
[0055] After the transference of the semiconductor wafers W is
completed, the transferring mechanism 22 laterally retracts
(evacuates) from the operating position A into the evacuating
position B in the other side region of the housing 1 by means of
the pivoting arm 23.
[0056] After the thermal processing is completed, the lid 17 is
lowered, and the boat 3 after the thermal processing is conveyed
out from the furnace 4 into the loading area Sb. The shutter 18
hermetically closes the opening 4a of the furnace immediately after
the lid 17 is taken off with the boat 3. Thus, only little heat
leaks from the opening 4a of the furnace 4 into the loading area
Sb, so that the heat seldom influence the instruments in the
loading area Sb. After the boat 3 after the thermal processing is
conveyed out from the furnace 4, as shown in FIG. 6, the boat
conveying mechanism 21 conveys another boat 3 before the thermal
processing waiting on the first placing portion 19a to the second
placing portion 19b ({circle over (1)}). Then the boat conveying
mechanism 21 conveys the boat 3 after the thermal processing from
the first lid 17 to the first placing portion 19a ({circle over
(2)}). Then, the boat conveying mechanism 21 conveys the boat 3
before the thermal processing placed on the second placing portion
19b onto the lid 17 ({circle over (3)}). That is, the boat
conveying mechanism 21 conveys the boats in such a manner that the
boat 3 before the thermal processing never passes under lee of the
other boat 3 after the thermal processing. Therefore, the
semiconductor wafers W in the boat 3 before the thermal processing
are prevented from being contaminated by particles or gases coming
from the boat 3 after the thermal processing when the boats 3 are
conveyed. The boat 3 before the thermal processing is relatively
further away from the other boat 3 after the thermal processing
immediately after the latter is conveyed out from the furnace.
Thus, the influence from the boat 3 after the thermal processing to
the other boat 3 before the thermal processing is effectively
restrained or prevented.
[0057] The boats 3 being conveyed and the transferring mechanism 22
are effectively prevented from interfering with each other because
the latter evacuates not upward but laterally from the boat
conveying mechanism 21. The shutter 18 which horizontally pivots to
open and close and the transferring mechanism 22 are also prevented
from interfering with each other because the latter evacuates not
upward but laterally.
[0058] After the boat 3 before the thermal processing is conveyed
onto the lid 17, the boat 3 and the lid 17 are introduced into the
furnace 4 through the opening 4a where the shutter 18 is opened.
The next thermal processing is conducted on the semiconductor
wafers W in the boat 3. On the other hand, after the boat 3 after
the thermal processing is conveyed onto the first placing portion
19a, the processed semiconductor wafers W in the boat 3 are
transferred back from the boat 3 into the vacant carrier 2 on the
carrier-placing portion 11 by means of the transferring mechanism
22. Then, the above cycle is repeated.
[0059] Another embodiment of the invention will now be described in
more detail with reference to FIGS. 7 to 10. FIG. 7 is a schematic
perspective view of another embodiment of the vertical thermal
processing unit of the invention. The exterior portion and the
inside walls of the processing unit are not shown in FIG. 7 for
convenience of the illustration. A boat conveying mechanism 105
comprises: a first pivoting arm 151 for conveying a wafer-boat 142
from a first placing portion onto a boat-elevator 141, a second
pivoting arm 152 for conveying the wafer-boat 142 from the
boat-elevator 141 onto a second placing portion, and a boat-moving
mechanism 153 for conveying the wafer-boat 142 from the second
placing portion onto the first placing portion.
[0060] The boat-moving mechanism 153 comprises: a boat-stage 154 on
which the wafer-boat 142 is placed, a guide rail 155 for guiding
the boat-stage 154 between the first placing portion and the second
placing portion, and driving means (not shown) for driving the
boat-stage 154.
[0061] Each proximal end of the first pivoting arm 151 and the
second pivoting arm 152 is rotatably attached at each pivoting
center shaft 156 or 157. As shown in FIG. 9, a flange portion 147
is provided at the lower end portion of the wafer-boat 142. A
ring-shaped protrusion 147a is provided at the lower surface of the
flange portion 147 for fitting with a thermal cylinder 141a on the
boat-elevator 141. Each free end of the first pivoting arm 151 and
the second pivoting arm 152 has a cut-out portion for avoiding
interfering with the ring-shaped protrusion 147a, and is adapted to
support the lower surface of the flange portion 147.
[0062] As shown in FIG. 9, each of the first pivoting arm 151 and
the second pivoting arm 152 has a clump mechanism, which consists
of at least two clump members 158 adapted to laterally fasten the
flange portion 147 of the wafer-boat 142 placed on the arm 151 or
152. Specifically, the clump members 158 are adapted to fasten and
release the flange portion 147 of the wafer-boat 142 by means of an
open-closing mechanism (not shown). The clump members 158 may also
fasten and release the flange portion 147 of the wafer-boat 142 by
making use of an elastic force of an elastic member such as a
spring or an elastic rubber (not shown). Thus, the wafer-boat 142
is prevented from falling down while the pivoting arm 151 or 152 is
pivoting. The numeral sign 159 in FIG. 9 indicates the driving
means such as a motor, which drive the first pivoting arm 151 or
the second pivoting arm 152 to pivot.
[0063] In FIG. 8, an imaginary X-axis is extending in the
horizontal front-rear direction with respect to a transferring
stage 102, through the center axis A of the wafer-boat 142 placed
on the boat-elevator 141. An imaginary Y-axis is extending in the
horizontal direction perpendicular to the X-axis. The pivoting axes
156, 157 of the first pivoting arm 151 and the second pivoting arm
152 are arranged on the Y-axis symmetrically with respect to the
center axis A. Specifically, as shown in FIG. 8, the pivoting axes
156, 157 are disposed in left and right side regions of the loading
area 104, respectively.
[0064] The first placing portion P1 and the second placing portion
P2 of the boat-stage 154 are arranged symmetrically with respect to
the X-axis, as shown as two-dot chained lines in FIG. 8. A filter
unit 146 for making a clean gas flow is disposed adjacently to the
lateral wall 145 near the first placing portion P1 defining the
loading area 104. The clean gas flow made by the filter unit 146 is
adapted to flow toward the second placing portion P2 through the
first placing portion P1 in the loading area 104. The lateral wall
near the second placing portion P2 defining the loading area 104 is
adapted to absorb the clean gas. The pivoting arm 151 is located
below the filter unit 146.
[0065] For the sake of the clean gas flow in the loading area 104,
the first placing portion P1 is preferably used to load the
wafer-boat into the furnace 140, and the second placing portion P2
is preferably used to unload the wafer-boat from the furnace 140.
Specifically, semiconductor wafers W are transferred into the
vacant wafer-boat 142 at the first placing portion P1. Then, the
wafer-boat 142 is conveyed onto the boat-elevator 141 and they are
conveyed into the thermal processing furnace 140 (loading). The
wafer-boat 142 after the thermal processing is conveyed from the
boat-elevator 141 onto the second placing portion P2. The processed
semioconductor wafers W are taken out from the wafer-boat 142 at
the second placing portion P2 (unloading). Thus, the semiconductor
wafers W before the thermal processing are always exposed to the
clean gas flow to be prevented from being contaminated by particles
or the like, so that the semiconductor wafers W can be loaded into
the thermal furnace 140 with the surfaces thereof kept clean. On
the other hand, the wafers W after the thermal processing are
unloaded from the thermal furnace 140 under the lee with respect to
the clean gas flow. Thus, the wafers W after the thermal processing
may be contaminated by particles or the like. However, the wafers W
after the thermal processing are then conveyed to the washing step
and the next processing step, so that if particles adhere to the
surfaces thereof, the particles are removed in the washing
step.
[0066] The above thermal processing unit operates as below. At
first, a cassette 120 is placed on the transferring stage 102 from
the outside by an operator or an automatic conveying robot not
shown. The cassette 120 is conveyed onto the supporting stage 130
for transferring wafers by means of a cassette-transferring
apparatus 103. The cassette 120 may be stored temporarily depending
on the progress situation of the thermal processing.
[0067] Then, semiconductor wafers W are taken out from the cassette
120 on the supporting stage 130 by means of a wafer-transferring
apparatus 143. The semiconductor wafers W are aligned by a notch
aligning apparatus 144, and conveyed into the wafer-boat 142 at the
first placing portion P1. The wafer-boat 142 is placed onto the
boat-elevator 141 by the first pivoting arm 151, and loaded into
the thermal processing furnace 140.
[0068] After the thermal processing is completed, the wafer-boat
142 is conveyed out from the thermal furnace 140, and conveyed from
the boat-elevator 141 to the second placing portion P2 by the
second pivoting arm 152. The processed semiconductor wafers W are
taken out from the wafer-boat 142 and conveyed into the cassette
120 on the supporting stage 130 by the wafer-transferring apparatus
143. The cassette 120 filled with the processed semiconductor
wafers W is conveyed to the outside through the transferring stage
102.
[0069] FIGS. 10A to 10F schematically show the moving flow of the
wafer-boats. In FIGS. 7 to 9, the wafer-boats are indicated by the
same numeral sign 142, but in FIGS. 10A to 10F, two wafer-boats are
indicated by the different numeral signs 148 and 149, respectively.
In addition, in FIGS. 10A to 10F, the numeral signs W1 and W2
indicate the wafer before the thermal processing and the wafer
after the thermal processing, respectively. The first placing
portion is disposed near the filter unit 146. For example, the
first placing portion is shown as a position occupied by the
wafer-boat 149 in FIG. 10A.
[0070] While the first wafer-boat 148 is loaded into the thermal
processing furnace 140 and undergoes the thermal processing, the
wafers W1 before the thermal processing are transferred into the
vacant second wafer-boat 149 placed on the boat-stage 154 at the
first placing portion (see FIG. 10A).
[0071] After the thermal processing of the first wafer-boat 148 is
completed, the first wafer-boat 148 is unloaded, and conveyed to
the second placing portion by the second pivoting arm 152. At the
same time, the second wafer-boat 149 is conveyed from the first
placing portion onto the boat-elevator 141 below the thermal
furnace 140 by the first pivoting arm 151 (see FIG. 10B). Then, the
boat stage 154 becomes empty and moves back from the first placing
portion P1 to the second placing portion P2 for receiving the
unloaded first wafer-boat 148 from the second pivoting arm 152.
[0072] While the second wafer-boat 149 is loaded into the thermal
processing furnace 140 and undergoes the thermal processing, the
wafers W2 after the thermal processing are taken out from the first
wafer-boat 148 placed on the boat-stage 154 at the second placing
portion (see FIG. 10C).
[0073] After the first wafer-boat 148 becomes vacant, the boat
stage 154 moves from the second placing portion P2 to the first
placing portion P1 with the first wafer-boat 148 placed thereon.
While the second wafer-boat 149 undergoes the thermal processing in
the thermal processing furnace 140, the wafers W1 before the
thermal processing are transferred into the first wafer-boat 148
placed on the boat-stage 154 at the first placing portion (see FIG.
10D).
[0074] After the thermal processing of the second wafer-boat 149 is
completed, the second wafer-boat 149 is unloaded, and conveyed to
the second placing portion by the second pivoting arm 152. At the
same time, the first wafer-boat 148 is conveyed from the first
placing portion onto the boat-elevator 141 below the thermal
furnace 140 by the first pivoting arm 151 (see FIG. 10E). Then the
boat stage 154 becomes empty and moves back from the first placing
portion P1 to the second placing portion P2 for receiving the
unloaded second wafer-boat 149 from the second pivoting arm
152.
[0075] While the first wafer-boat 148 is loaded into the thermal
processing furnace 140 and undergoes the thermal processing, the
wafers W2 after the thermal processing are taken out from the
second wafer-boat 149 placed on the boat-stage 154 at the second
placing portion (see FIG. 10F).
[0076] After the second wafer-boat 149 becomes vacant, the boat
stage 154 moves from the second placing portion P2 to the first
placing portion P1 with the second wafer-boat 149 placed thereon.
Then, the cycle of FIGS. 10A to 10F is repeated.
[0077] In the above embodiment, the pivoting axes 156, 157 of the
pivoting arms 151, 152 are arranged on the Y-axis symmetrically
with respect to the center axis A of the wafer-boat 142 placed on
the boat-elevator 141. The first placing portion P1 and the second
placing portion P2 are arranged on the side of the transferring
stage 102 with respect the center axis A, symmetrically with
respect to the X-axis, which is perpendicular to Y-axis and passes
through the center axis A. Therefore, the width of the thermal
processing unit can be effectively reduced, compared with the
conventional one wherein the first placing portion and the second
placing portion are arranged laterally to the X-axis in one side
region of the loading area 104 and only one arm transfers
wafer-boats.
[0078] This invention is not limited by the above embodiments and
may be modified variously within the scope of claim. For example,
the substrates may be not only the semiconductor wafers but also
glass substrates or LCD substrates.
* * * * *