Note: Descriptions are shown in the official language in which they were submitted.
This invention relates to tiltable support brackets for
slidably supporting rails on which are carried boats containing
semiconductor wafers for processing. The invention also relates to
processing apparatus embodying such brackets.
Quartz boats, carring wafers, are supported on two
parallel rails, usually of quartz or silicon. The ends of the rails
are in-terconnected, usually at both ends. The rails, carrying the
boats, are slid into a furnace, in which the wafers are treated or
processed, the rails being slid in and out by means of a feed
mechanism connected to an end cap or plate, which normally seals the
open, entry, end oF the furnace when the support rails are fully
inserted. A hook extending from the front or inner face of the end
cap or plate engages in a small loop or similar structure formed on
the interconnecting member at the outer ends of the rails.
The feed mechanism is actuated, normally, by a con-trol
system and in conventional forms of apparatus the support rails slide
at all times on the inner surFace of the Furnace tube. The rails may
be loacled ~ith boats and then -the inner ends of the rails inserted
into the open end of the furnace tube, the loop a-t the outer ends
resting on the hook extending from the encl cap or pla-te. The rails
are thus supported initially only at each end~
As the rails are pushed into -the furnace tube,
vibration can occur. This may be due to roughness developed on -the
rails during processing and/or roughness on the inner surface of the
furnace tube. Sometimes the vibration can build up to dangerous
levels and breakage of one or both support rails can occur. This
results in boats, and ~lafers also being dropped with possible
~x
breakage of boats and damage to wafers. If the rails have been
partially inserted before breakage occurs, boats and wafers can fall
down onto the inner surface of the furnace tube and have to be
retrieved. The furnace tube will be at opera-ting temperature at this
time and therefore it can be difficult to retrieve boats and wafers
and breakage of the furnace tube itself may also occur,
The present invention provides a tiltable bracket which
acts to support the support rails as they are slid into the furnace,
the bracket being hinged down by the end cap or pla-te to enable the
end plate to close off the open end of the furnace tube. On
withdrawal of the end cap or plate, and support rails, frorn the
furnace the end cap or plate engages a projection on the bracket to
cause it to pivot up and support the rails. More than one such
bracket can be provided depending upon -the length of the support
rails and the weight being carried.
Broadly a bracket has -two spaced pillars, at the top
en(ls o-f which are bearings rotatably holding a round shaft extending
between the pillars. The bottom ends of -the pillars are attached -to
a firs-t member of two members hingedly connected. The second member
2~ is adapted to be attached to a base surface of an apparatus. A
projection extends up from the first member. An end plate of a
furnace pushes agains-t the pillars as the plate moves towards the
furnace and hinges -the bracket over and down for passage of the end
plate. On reverse rnovement of the end plate, it engages with the
projection from the first member and hinges the bracket up after
passage of the end plate.
The invention will be readily understood by the
following description of certain embodiments of the invention in
conjunction with the accompanying drawings, in which:-
Figure 1 is a perspective view of one form of bracket;
Figures 2, 3 and 4 are top, rear and side viewsrespectively of the bracket of Figure 1;
Figures 5 and 6 illustrate very diagrammatically an
apparatus embodying brackets as in Figures 1 to 4, illustrating -the
operation of the brackets;
Figure 7 is a partial top plan view of the connection
between support rails, end plate and actuator~
As illustrated in Figure 1, and also in Figures 2, 3
and 4, a bracket has two flat rnembers 10 and 11 hingedly connected at
12. On the firs-t flat member 10 are two spaced apart pillars,
indicated generally at 13. In the example the second flat member 11
has two slots 14 through which are passed screws for attachment to a
base surface of a processing apparatus. Extending rearwards, and
upwards from the first flat member 10 is a projection or lever 15.
The lever 15 extends to a lower height -than the pillars.
Considering the pillars 13 in more detail, in the
example illustrated, each pillar is cornprised of three main parts. A
base 16 is attached at its lower end to -the flat member 10 and has a
bore 17 extending down from its top end. If desired the base 16 can
be formed of tube. A screw 18 extends through the side of the base
to the bore 17. A central part 19 has a lower portion 20 a sliding
fit in the bore 17 and can be locked in position by the screw 1~.
The central part also has a threaded upper portion 21~ A top part 22
has a lower portion 23 which has a threaded bore 24 into which screws
-the threaded upper portion of the cen-tral part. The top member 22
also has a top portion 25 within which is mounted a bearing 26. The
rotational axes of the bearings in the two pillars are coa~ial and a
shaft 27 is mounted at each end in the bearings. The bearings 26 are
conveniently ball bearings. Collars 28 on the ends of the shaft 27
ensure posi-tioning of the shaft 27, the collars locked in position by
screws 19. A lock nut 30 can be provided on the threaded upper
portion 21 of the central part.
To provide for adjustment of the height of the shaft
27, to suit variations in various different furnaces, and to provide
for individual adjustment to meet variations in the level of the
surface on which the brackets are mounted in a particular furnace,
the construction provides two stages of adjus-tment. Thus a
rela-tively coarse adjustment is provided by movement of the lower
portion 20 of the central part 19 in and out o-f the bore 17 of the
base 16, and being held in any desired position by the screws 18. A
finer adjustment is provided by rotating the top part 22 on -the
threaded upper part 21 of the central part 19. To do this lat-ter
adjus-tment the shaft 27 rnust be removed from the bearings 26. The
shaft 27 is made -to be a relatively easy slide fit in the bore of the
bearing. The sliding movemen-t to be supported by -the shaft 27 is
relatively slow and the requirement of the bearings 26 is to provide
a smooth movement, the loading of the bearings being very low.
In operation, the end plate of the furnace assembly
approaches from the right in Figures 1 and 4 when a furnace is being
loaded, the support rails resting, and sliding, on the shaft 27. The
end pla-te contacts the pillars 13 and they pivo-t or hinge over, on
~ 3~ t3
the flat member 10, eventually dropping down until the top parts 25
rest on the mounting surface, the lever 15 extending up behind the
end plate. On withdrawal from the furnace the end plate passes over
the pillars 13 and contacts the lever 150 As the end plate continues
to move, to the right in Figures 1 and 4, the lever acts to pivot the
flat member 10 and attached pillars 13 until the pillars are upright
and the shaft moves under, and supports, the support rails.
Figures 5 and 6 illus-trate very diagrammatically one
particular arrangement of furnace embodying brackets as described
above. The furnace~ indicated generally at 40, has a furnace tube 41
supported therein at one end. Only the front part of the furnace
tube 41 and surrounding enclosure 42 is shown, the enclosure
extending for the length of the furnace. At the rear end are the
means for supplying the various gases and vapours to the furnace
tube, with associated control means. This is conven-tional and is of
normal form, well known. At the other end of the furnace is a
further enclosure, indicated at 43, which can contain indicators,
control input devices and similar items. Extending between the
enclosures 42 and 43 is a base 44 with a top surface 45. Also
extending between the enclosures 42 and 43 is a back wall 46 behind
which runs the mechanism for inserting and withdrawing the support
rails, boats and wafers. A typical form of mechanism is a threaded
rod which is rotated by an electric motor mounted in enclosure 43.
Rotation of the rod causes an actuating member to traverse, and the
actuating member extends through a slot 47 in the back wall 46 and is
attached to the furnace end plate. The actuating member is seen at
4~ and the end plate at 49. Direction of rotation of the -threaded
rod determ1nes the direction of movement of actuatiny member ~, and
thus the end plate 49. Again this mechanism is conventional.
Extending from the front surface of the end plate 49 is
a hooked member 50. This hooked member engages in a loop or ring 51
at the outer end of the support rails 52. This is seen more clearly
in Figure 7, where the outer ends of the support rails 52 are shown
connected -together in a U-form, at 53, the loop or ring 51 extending
from the U, and resting over the hooked member 50.
Figure 5 illustrates the apparatus or -furnace in the
substantially fully withdrawr position, while Figure 6 illustrates a
partially inserted, or partially withdrawn, position. In the
arranyement of Figures 5 and 6, three support brackets are provided,
at 60. In Figure 5 the inner ends of the support rails 52 are
inserted in the open end of the furnace tube and the rails are
supported on the brackets 60. 3Oats are indicated in dot-ted outline
at 61, resting on the rails 52.
As the actuator moves to the leftg in Figure 5, the
support rails, and boats, move into the furnace tube, the end pla-te
49 moving towards the outerrnost bracket 60. Even-tually the end plate
2n contacts the bracket and as movement continues the bracket pivots
over and eventually clrops down, permitting the encl plate to continue
over the bracket. Lever 15 tips up behind the end plate. This
situation is illustrated in Figure 6.
Continued movement of the actuator, and end plate,
continues insertion of rails 52 and boats 61, and each bracket 60 is
progressively tipped over and down. The support rails are
increasingly supported by the inner surface of -the furnace ~ube as
the rails are inserted, although the rails are at least partially
supported by the brackets for the majority of their travel. By the
time the last bracket has been tipped over, the length of rails 52
extending out of the open end of the furnace tube is relatively short
and vibration is substantially reduced. ~ h a long length of the
rails extending out of the furnace tube, unsupported, as is
conventionally the case, the rails are somewhat flexible and thus any
vibra-tion can build up to quite serious levelsO Also, support of the
rails, and boats, by the brackets, relieves the actuator 48 from
having to support at least a substantial portion of the weight of
boats and wafers and also reduces the possibility of vibration
arising from the actuator.
Eventually the end plate 49 is closed against the outer
end of the furnace tube, and the process or treatment proceeds. At
the end oF the process cycle, the rails and boats are withdrawn from
the furnace tube. The actuator 4~ moves the end plate 49 to the
right, in Figures 5 and 6, and as the end plate moves over the first
bracket 60l which will be in the down position, the end plate
contacts the lever 15 and continued movement of the end plate pivots
up the bracket until the shaft 27 supports the support rails.
Continuecl outward movernent of the end plate successively pivots up
the brackets 60.
The number of brackets provided can be varied,
depending upon the length of the support rails 52 and the weigh-t of
the boats and wafers to be supported by the rails 52. It is the
length of support rail which is itself unsupported which creates the
problem of unacceptable vibration, resulting in possible breakage~
and spilling of boats and wafers.
The brackets are usually designed so that when
pivotted to an upright position by interaction between end plate and
levers 15, center of gravity of the pillars 13 and shaft 27 rnoves
over the pivotal axis at 12 and the brackets continue to an upright
position even after contact between end plate and lever ceases.
The particular form of the lever 15 can vary depending
upon the particular form of the end plate. The lever can be central,
offset, or more than one lever can be provided. Also, the actual
form of the pillars 13 can vary. For example, the threaded portion
can be the lower part, screwing into a threaded bore in the base 16.
The upper portion of the central member is then an axially sliding
fit in a bore in the top member. Another alternative is with both
upper and lower parts of the central member being threaded,
cooperating wi-th threaded bores, in the base and top member. If
desired only one stage of adjustment need be provided. Other
variations in the pillars 13 can readily be appreciated. The second
member 11 while described and illustrated as a single flat member,
can be of other forms. While a single member 11 is more convenient,
the member could comprise two, or rnore, independent sections, each
hingedly attachecl to the first member 10. The term second member is
intended to cover one continuous member, or a plurali-ty of sec-tions
cooperating together as a unit.
