U.S. patent application number 10/952095 was filed with the patent office on 2005-10-13 for support jig of quartz glass for receiving wafer-like substrates of semiconductor material.
This patent application is currently assigned to Heraeus Quarzglas GmbH & Co., KG. Invention is credited to Herbert, Thorsten, Maul, Armin, Stock, Roland, Weber, Jurgen.
Application Number | 20050224429 10/952095 |
Document ID | / |
Family ID | 32668317 |
Filed Date | 2005-10-13 |
United States Patent
Application |
20050224429 |
Kind Code |
A1 |
Maul, Armin ; et
al. |
October 13, 2005 |
Support jig of quartz glass for receiving wafer-like substrates of
semiconductor material
Abstract
A support jig of quartz glass for receiving wafer-like
substrates of semiconductor material in a vertical orientation
comprises two spaced-apart circular end plates (10) which are
interconnected by means of at least three transverse rods (1, 2, 3)
extending in parallel with one another and between the end plates.
They are provided with slots (4) for receiving the substrates, the
slots (4) being open towards the substrate to be received and
having a predetermined maximum slot depth, and they are arranged in
a partial circle around the circular edge (5) of the end plates
(10) such that an envelope (6) which encloses the partial circle on
the outside projects nowhere beyond the circular edge (5). At least
part of the transverse rods (1, 2, 3) have a radial cross-sectional
profile which is configured as a circular form with a flattening
(21, 31). The transverse rods (1, 2, 3) are arranged around the
partial circle such that the flattening (21, 31) is oriented
towards the circular edge of the end plates.
Inventors: |
Maul, Armin;
(Grebenheim/Nosberts, DE) ; Stock, Roland;
(Freigericht, DE) ; Weber, Jurgen; (Kleinostheim,
DE) ; Herbert, Thorsten; (Mombris, DE) |
Correspondence
Address: |
TIAJOLOFF & KELLY
CHRYSLER BUILDING, 37TH FLOOR
405 LEXINGTON AVENUE
NEW YORK
NY
10174
US
|
Assignee: |
Heraeus Quarzglas GmbH & Co.,
KG
Hanau
DE
|
Family ID: |
32668317 |
Appl. No.: |
10/952095 |
Filed: |
September 28, 2004 |
Current U.S.
Class: |
211/41.18 |
Current CPC
Class: |
H01L 21/67313
20130101 |
Class at
Publication: |
211/041.18 |
International
Class: |
A47G 019/08 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 3, 2004 |
DE |
20 2004 005378.0 |
Claims
What is claimed is:
1. A support jig of quartz glass for receiving wafer-like
substrates of semiconductor material in a vertical orientation,
comprising two spaced-apart circular end plates (10) which are
interconnected by means of at least three transverse rods (1, 2, 3)
extending in parallel with one another and between the end plates,
which are provided with slots (4) for receiving the substrates, the
slots (4) being open towards the substrate to be received and
having a predetermined maximum slot depth, and which are arranged
in a partial circle around the circular edge (5) of the end plates
(10) such that an envelope (6) which encloses the partial circle on
the outside projects nowhere beyond the circular edge (5),
characterized in that at least part of the transverse rods (1, 2,
3) have a radial cross-sectional profile which is configured as a
circular form with a flattening (21, 31), and that the transverse
rods (1, 2, 3) are arranged around the partial circle such that the
flattening (21, 31) is oriented towards the circular edge of the
end plates.
2. The support jig according to claim 1, characterized in that the
flattening (21, 31) contacts the circular edge (5) of the end
plates.
3. The support jig according to claim 1 or claim 2, characterized
in that the flattening (21, 31) is configured as a planar
surface.
4. The support jig according to claim 1 or claim 2, characterized
in that the flattening is configured as a curved surface.
5. The support jig according to any one of the preceding claims,
characterized in that the tangent to the flattening (21) at the
point of contact extends in at least one of the transverse rods (2)
in parallel with the slot bottom and in at least one further
transverse rod (1, 3) at an oblique angle relative to the slot
bottom.
6. The support jig according to any one of the preceding claims,
characterized in that the transverse rods (1, 2, 3) have a maximum
outer diameter of more than 22 mm, preferably 25 mm or more.
7. The support jig according to any one of the preceding claims,
characterized in that the transverse rods (1, 2, 3) have a maximum
outer diameter of 30 mm or less.
8. The support jig according to any one of the preceding claims,
characterized in that at least part of the transverse rods have a
radial cross-sectional profile in which a second flattening is
provided in the area of the slots.
9. The support jig according to any one of the preceding claims,
characterized in that the flattening (21, 31) and/or the slots (4)
have surfaces that are fire polished.
10. The support jig according to claim 9, characterized in that the
fire polish is produced by using a robot.
11. The support jig according to any one of the preceding claims,
characterized in that the slots (4) are produced in a
machine-controlled manner.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a support jig of quartz
glass for receiving wafer-like substrates of semiconductor material
in vertical orientation, the jig comprising two spaced-apart
circular end plates which are interconnected by means of at least
three transverse rods extending in parallel with one another and
between the end plates,
[0002] which are provided with slots for receiving the substrates,
the slots being open towards the substrate to be received and
having a predetermined maximum slot depth, and
[0003] which are arranged in a partial circle around the circular
edge of the end plates such that an envelope which encloses the
partial circle on the outside projects nowhere beyond the circular
edge.
BACKGROUND OF THE INVENTION
[0004] In the semiconductor-technological processing of wafers,
such support jigs are used for storing and transporting the wafers.
A jig of the above-mentioned type is known from DE 36 34 935 C2.
This is a vertical type jig consisting essentially of two boundary
plates that are interconnected by slotted transverse webs.
[0005] Such support jigs have standard dimensions which are exactly
matched to mount the jigs in a process container, for instance in
an ion etching system or a furnace. This is particularly true for
the outer dimensions of the support jig, i.e. the length and the
outer diameter of the boundary plates, which are circular as a
rule.
[0006] Arrangement and dimensions of the transverse rods are also
strictly limited in terms of process engineering. The transverse
rods are arranged around the periphery of the boundary plates in a
partial circle such that the envelope which encloses the partial
circle on the outside projects nowhere beyond the outer diameter of
the boundary plates. A further limitation of the transverse rods is
due to the predetermined outer diameter of the substrate wafers.
This limitation consists in that the enveloping circle on the slot
bottom of the slots must not be smaller than the outer diameter of
the substrate wafers. In other words, the transverse rods are
arranged and configured such that they are suited for receiving the
substrate wafers on the one hand and do not project beyond the
circular edge of the end plates on the other hand. Attention must
here be paid that the slot depth of the transverse rods must not
exceed a predetermined maximum value because the surface areas of
the substrate wafers resting in the slots cannot be processed in an
exact manner and are thus not suited for the production of
semiconductor components.
[0007] When quartz glass jigs are used, the fundamental problem
arises that these get bent when used at high temperatures and may
thus turn useless at an early stage.
SUMMARY OF THE INVENTION
[0008] It is therefore the object of the present invention to
provide a quartz glass support jig of high thermal stability.
[0009] Starting from a support jig with the features indicated at
the outset, this object is achieved according to the invention in
that at least part of the transverse rods have a radial
cross-sectional profile configured as a circular form with a
flattening, and that the transverse rods are arranged around the
partial circle such that the flattening is oriented towards the
circular edge of the end plates.
[0010] In the support jig of the invention, the transverse rods do
not have an exactly circular radial cross-sectional profile as is
known in the prior art, but a cross-sectional profile in circular
form that is provided with at least one flattening. Said flattening
is configured as a planar or curved surface on the outer surface of
the transverse rods and extends over the entire length thereof.
[0011] Said flattening permits the use of transverse rods with
larger outer diameters without the rods projecting beyond the
circular edge of the end plates and without requiring an
enlargement of the slot depth beyond the predetermined maximum.
[0012] Despite strict specifications regarding the maximum slot
depth, the outer diameter of the support jig (outer diameter of the
end plates) and the outer diameter of the substrate wafers, the
inventive modification of the transverse rods with a flattening
thus permits the configuration thereof with a cross-section that is
thicker on the whole, so that the risk of plastic deformation in a
high-temperature process is reduced as, despite the predetermined
slot depth, the flattening permits a larger supporting
cross-sectional area in the modification of the transverse rods
according to the invention than in the transverse rods with a
circular cross-section as are known in the prior art.
[0013] According to the invention all of the transverse rods, or
part thereof, are provided with such a flattening of the
cylindrical outer surface.
[0014] Preferably, the flattening contacts the circular edge of the
end plates.
[0015] In this embodiment the transverse rods are displaced as much
as possible to the outside towards the circular edge of the end
plates. This has the effect that the envelope which encloses the
partial circle of the transverse rods on the outside corresponds to
the outer diameter of the end plates and the transverse rods can be
formed with a maximum thickness (outer diameter).
[0016] In a first preferred variant of the support jig of the
invention, the flattening is configured as a planar surface.
[0017] A planar surface which extends in parallel with the
longitudinal axis axially along the transverse rods can be produced
with little manufacturing efforts, for instance by grinding.
[0018] As an alternative, the flattening is designed as a curved
surface in an equally preferred second variant of the support jig
of the invention.
[0019] In this instance, the flattening has a curvature contacting
the outer edge of the end plate.
[0020] In this embodiment, with the maximally possible outer
diameter of the transverse rods, the amount of material removed
from said rods for producing the flattening is as small as
possible, so that a supporting cross-sectional area that is as
large as possible will remain, which contributes to improved
thermal stability.
[0021] In this respect it has also turned out to be advantageous
when the tangent to the flattening at the point of contact extends
in at least one of the transverse rods in parallel with the slot
bottom and in at least one further transverse rod at an oblique
angle relative to the slot bottom.
[0022] The transverse rod in which the tangent to the flattening at
the point of contact extends in parallel with the slot bottom is
here arranged in the area of one of the central axes which divide
the circular area of the end plate. The other transverse rod or the
other transverse rods are arranged outside said central axes.
[0023] In a preferred embodiment of the support jig according to
the invention, the transverse rods have a maximum outer diameter of
more than 22 mm, preferably 25 mm or more.
[0024] Apart from the type of quartz glass, the outer diameter of
the transverse rods is of relevance to the thermal stability
thereof. The larger the outer diameter and the supporting
cross-sectional area are, the smaller is the risk of deformation
during use of the support jig.
[0025] However, it should be noted that with an increasing outer
diameter the necessary slot depth will also increase so that the
enveloping circle around the slot bottoms corresponds to the outer
diameter of the substrate wafer or, for avoiding a larger slot
depth, a stronger flattening is needed, which means enhanced
manufacturing efforts. The ideal outer diameter has to be
determined as a compromise between the requirements for high
thermal stability on the one hand and for minimum efforts in
producing the axial flattening on the other hand.
[0026] That is why a support jig is preferred, in which the
transverse rods have a maximum outer diameter of 30 mm or less.
[0027] A further improvement is achieved when the transverse rods
have, at least in part, a radial cross-sectional profile in which a
second flattening is provided in the area of the slots.
[0028] Hence, said transverse rods have two flattened portions that
in a top view on the radial cross-section are exactly or
approximately opposite to each other. The radial shape of the
transverse rods is slightly oval. The supporting cross-section can
thereby be increased further and the predetermined slot depth can
nevertheless be maintained. Such a support jig is characterized by
a particularly high thermal stability.
[0029] Furthermore, it has turned out to be advantageous when the
flattening and/or the slots have surfaces that are
fire-polished.
[0030] The flattening, and normally also the slots, are produced by
grinding. Cracks are thereby introduced into the surface, the
cracks reducing the mechanical strength of the support jig, also at
high temperatures. Said surface cracks are closed by fire-polishing
the ground surfaces, which further contributes to the thermal
stability of the support jigs of the invention.
[0031] A particularly high dimensional stability is achieved when
the fire polish is produced by using a robot.
[0032] In this respect it has turned out to be particularly useful
when the slots are produced in a machine-controlled way.
[0033] The slots effect a mechanical weakening of the transverse
rods, which accelerates deformation at high temperatures. As a
rule, a transverse rod has more than 100 slots. Due to the
machine-controlled formation of the slots, all slots have the same
slot depth and slot width, and the slot distance is observed. Weak
points are thus avoided and a particularly high thermal stability
of the support jig of the invention is thereby accomplished.
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] The invention will now be explained with reference to
embodiments and a drawing in more detail. In the drawing,
[0035] FIG. 1 shows an embodiment of a support jig of the invention
in a top view on the flat side of an end plate;
[0036] FIG. 2 is an enlarged illustration of detail C of FIG.
1;
[0037] FIG. 3 is an enlarged illustration of detail B of FIG. 1;
and
[0038] FIG. 4 shows an embodiment of a support jig according to the
prior art in a top view on the flat side of an end plate.
DETAILED DESCRIPTION
[0039] FIG. 4 is a sectional illustration of a vertical type jig
according to the prior art in a view on one of the two end plates
10 at the front sides. Said end plate 10 consists of a circular
quartz glass plate having a thickness of about 10 mm and an outer
diameter of 315 mm. The end plate 10 is connected by means of
transverse quartz glass rods 41, 42, 43 to a further end plate (not
shown in FIG. 4) which is arranged opposite to and in parallel with
end plate 10. Each of the transverse rods is provided with about
130 slots 4 for receiving semiconductor wafers. The slot depth is
6.5 mm, the slot width 4 mm, and the slot distance about 7.7
mm.
[0040] The transverse rods 41, 42, 43 have an exactly circular
radial cross-section. They are arranged on the outer periphery of
the end plate 10 such that they project nowhere beyond the outer
edge 5 thereof. In the view of FIG. 4, the transverse rods 41, 42,
43 form a partial circle around the outer edge 5 of the end plate
10, wherein the envelope 6 which encloses the partial circle on the
outside extends exactly around the outer edge 5.
[0041] The transverse rod 42 is arranged on one of the central axes
7 of the circular surface of the end plate 10, the slot bottom
being oriented towards the center point 8. The two other transverse
rods 41, 43 are arranged above the other central axis 9 of the
corresponding circular area, the slot bottom extending in parallel
with the axis of symmetry 7. The distance A between the slot
bottoms of the transverse rods 41 and 43 is 303 m. The diameter of
the transverse rods 41, 42, 43 is 22 mm and cannot be increased in
view of the predetermined specifications that allow for neither an
increase in slot depth nor components projecting beyond the outer
edge 5.
[0042] FIG. 1 shows the same view as FIG. 4, but on an end plate in
a vertical type jig according to the present invention. As far as
identical reference numerals are used in FIG. 1 as in FIG. 4,
identical or equivalent components of the support jig are referred
to, as have been explained above with reference to FIG. 4.
[0043] In contrast to the prior art, transverse quartz-glass rods
1, 2, 3 in the support jig according to the invention have an outer
diameter which is 25 mm at the most. To observe the predetermined
distance A of 303 mm between the slot bottoms of the transverse
rods 1 and 3 despite the increased cross-section thereof, the depth
of slots 4 is however not increased (said depth is always about 6.5
mm), but the transverse rods 1 and 3, like the transverse rod 2,
are provided with a flattening which contacts the outer edge 5 of
the end plate 10. The flattened portions 22, 23, which are shown in
detail in FIGS. 2 and 3, are produced by grinding and subsequent
fire polishing using a grinding machine and a robot for fire
polishing. The slots 4 were produced by means of a CNC grinding
machine.
[0044] FIG. 2 shows an enlarged illustration of the transverse rod
2 with the slot 4, the slot bottom 22 and the flattening 21. The
flattening 21 is configured as a planar surface having a width of 6
mm on the cylindrical outer surface of the transverse rod 2. The
transverse rod 2 is arranged on the end plate 10 such that the
tangent 23 to the outer edge 5 extends in parallel with the
flattening 21 and the slot bottom 22.
[0045] FIG. 3 is an enlarged illustration showing the transverse
rod 3 with the flattening 31 and the slot bottom 32 (the transverse
rod 1 is designed in mirror symmetry therewith). The flattening 31
is also designed as a planar axial surface, the tangent 33 to the
flattening 31 at the point of contact on the outer edge 5 enclosing
an angle of 7.degree. with the slot bottom 32. The length of the
flattening, i.e. the area adapted to the circular edge 5 by
grinding, is about 13 mm in the transverse rods 1 and 3.
[0046] The minimum outer diameter of the transverse rods 1 and 3 is
about 23 mm and the minimum outer diameter of the transverse rod 2
is about 24.5 mm.
[0047] As an alternative to the embodiment shown in FIG. 3, the
transverse rod 3 is provided with a flattening having a curvature
adapted to the outer edge 5. In this case said curvature is
configured, and the transverse rod 3 is arranged on the end plate
10, such that the tangent 33 to the flattening 31 at the point of
contact on the outer edge 5 encloses an angle of 7.degree. with the
slot bottom 32.
[0048] Although the specifications given by process engineering are
adhered to, specifically distance A, the outer diameter of the end
plates 10, and the depths of the slots 4, it is thereby possible to
provide a support jig of quartz glass that is characterized by high
temperature resistance.
* * * * *