U.S. patent application number 09/443701 was filed with the patent office on 2001-12-06 for processing apparatus.
Invention is credited to HAYASHI, KAZUICHI.
Application Number | 20010047762 09/443701 |
Document ID | / |
Family ID | 15394673 |
Filed Date | 2001-12-06 |
United States Patent
Application |
20010047762 |
Kind Code |
A1 |
HAYASHI, KAZUICHI |
December 6, 2001 |
PROCESSING APPARATUS
Abstract
A processing apparatus includes a susceptor provided in a
processing chamber and having an upper surface with a support area
on which a semiconductor wafer is placed, and an aligning ring
member movably arranged on the upper surface of the susceptor to
surround the support area, the ring member defining the shift of
the wafer placed on the support area and formed of a material
having a thermal expansion coefficient smaller than that of the
susceptor. A plurality of projections are provided on the
peripheral portion of the upper surface of the susceptor at
intervals along the ring member. A plurality of slots are provided
in the aligning ring member for receiving the corresponding
projections. The slots permit relative movement of the projection
received therein in a radial direction of the ring member, but
prohibit relative movement of the projections received therein in a
rotating direction of the ring member as a whole.
Inventors: |
HAYASHI, KAZUICHI;
(KOFU-SHI, JP) |
Correspondence
Address: |
Morrison & Foerster LLP
555 West Fifth Street suite 3500
Los Angeles
CA
90013-1024
US
|
Family ID: |
15394673 |
Appl. No.: |
09/443701 |
Filed: |
November 19, 1999 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
09443701 |
Nov 19, 1999 |
|
|
|
PCT/JP98/02094 |
May 12, 1998 |
|
|
|
Current U.S.
Class: |
118/728 ;
118/500; 156/345.51 |
Current CPC
Class: |
H01L 21/68785 20130101;
H01L 21/68721 20130101 |
Class at
Publication: |
118/728 ;
118/500; 156/345 |
International
Class: |
C23C 016/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 20, 1997 |
JP |
9-145856 |
Claims
1. A processing apparatus comprising: a processing chamber; A
susceptor which is placed in said processing chamber and has one
surface with a support area on which a processing object is set;
processing means for processing the processing object set in the
support area; an aligning ring member which is arranged on the
surface of said susceptor so as to surround the support area, and
defines movements of the processing object set on the support area
along the surface; and a plurality of movement regulating
mechanisms, provided to said aligning ring member and said
susceptor, for permitting relative movement of said aligning ring
member and said susceptor in a radial direction due to thermal
expansion/contraction difference of the aligning ring member and
the susceptor while prohibiting relative rotation thereof; each of
the movement regulating mechanisms comprising a projection portion
which is provided on said aligning ring member and projects to said
susceptor, and a guide portion which is provided on said susceptor
for receiving said projection portion provided on the aligning ring
member.
2. An apparatus according to claim 1, wherein said guide portion is
a groove formed in the susceptor.
3. An apparatus according to claim 1, wherein said aligning ring
member has an inner circumferential surface with a complementary
shape to an outer peripheral shape of the processing object.
4. An apparatus according to claim 1, wherein said processing means
is for processing the processing object using a plasma, said
susceptor is formed of a metallic material, and said aligning ring
member is formed of a high-heat-resistance and high-rigidity
nonmetallic material with a thermal expansion coefficient smaller
than that of the metallic material forming said susceptor.
5. An apparatus according to claim 4, wherein the nonmetallic
material is a ceramic material.
6. A processing apparatus comprising: a susceptor having one
surface with a support area on which processing object is placed;
processing means for processing the processing object placed on the
support area; an aligning ring member which is shiftably arranged
on the surface of said susceptor so as to surround the support
area, defines shift of the processing object placed on the support
area along the surface, and is formed of a material having a
thermal expansion coefficient smaller than that of said susceptor;
a plurality of projection portions which are provided on said
aligning ring member and project to said susceptor; and a plurality
of elongated guide portions which are provided to said susceptor
and receive the corresponding projection portions therein to permit
relative movement of said projection portions in a radial direction
while prohibiting relative movement in a direction along the ring
member.
7. A processing apparatus comprising: a susceptor having one
surface with a support area on which a processing object is placed;
processing means for processing the processing object placed on the
support area; an aligning ring member which is movably arranged on
the surface of the susceptor to surround the support area, the ring
member defining the shift of the processing object placed on the
support area and formed of a material having a thermal expansion
coefficient smaller than that of said susceptor; a plurality of
projections provided on said aligning ring member and projecting to
said susceptor; and a plurality of guide means provided to said
susceptor for receiving the corresponding projections,
respectively, at least one of said guide means having an elongated
shape to permit relative movement of the projection received
therein in a radial direction of the ring member, and said
plurality of guide means having shapes to prohibit, as a whole,
relative movement of the projections received therein in a rotating
direction of the ring member.
8. A processing apparatus comprising: a susceptor having one
surface with a support area on which a processing object is placed;
processing means for processing the processing object placed on the
support area; an aligning member which is movably arranged on the
surface of the susceptor to surround the support area, the aligning
member defining the shift of the processing object placed on the
support area and formed of a material having a thermal expansion
coefficient smaller than that of said susceptor; a plurality of
projections provided on said aligning member and projecting to said
susceptor; and a plurality of guide means provided to said
susceptor for receiving the corresponding projections,
respectively, the guide means having a shape to permit relative
movement of the projection received therein in a radial direction
of the aligning member and to prohibit, as a whole, relative
movement of the projections received therein in a rotating
direction of the aligning member.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This is a Continuation of Application PCT/JP98/02094, filed
May 12, 1998.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a processing apparatus
having a ring member for holding a processing object such as a
semiconductor wafer at an alignment position on a susceptor.
[0003] Generally in manufacturing a semiconductor integrated
circuit, processing including film formation and pattern etching is
repeatedly executed to form a large number of desired elements on a
substrate such as a semiconductor wafer. Such processing is
performed by placing the wafer on a susceptor inside a processing
chamber, and then supplying processing gas such as film formation
gas or etching gas from a shower head into the processing chamber
while the interior of the processing chamber is kept in vacuum.
[0004] In this case, to ensure high processing uniformity in the
plane of the wafer in, e.g., film formation and etching, the wafer
must be aligned and placed on the susceptor with high precision and
prevented from sliding and moving on the susceptor surface upon the
placement. In particular, even a slight shift of the wafer within
the plane or even a slight difference in horizontal level between
the upper ends of lifter pins for vertically moving the wafer with
respect to the susceptor may lead to sliding movement of the wafer
on the susceptor upon placing the wafer on the support surface of
the susceptor by the lifter pins.
[0005] In general, to prevent the movement of the wafer, an
aligning guide ring having an inner diameter slightly larger than
the diameter of the wafer is fixed to the peripheral edge portion
of the susceptor, and the wafer is placed within the ring.
[0006] FIG. 10 is a schematic sectional view of a conventional
susceptor. FIG. 11 is a plan view of the susceptor. As shown in
FIGS. 10 and 11, a guide ring 4 having an L-shaped section is
fitted on the peripheral edge portion of a thick disk-like
susceptor 2. An inner diameter L1 of the guide ring 4 is set
slightly larger than a diameter L2 of a wafer W by, e.g., about 1
mm. By placing the wafer W on the support surface of the susceptor
2 within the guide ring 4, the wafer W is aligned and prevented
from largely moving, i.e., sliding on the support surface.
[0007] The susceptor 2 and the guide ring 4 are generally made of a
ceramic material such as alumina (Al.sub.2O.sub.3) or aluminum
nitride (AlN). If the constituent material of the susceptor 2 is
the same as that of the guide ring 4, their thermal expansion
coefficients are the same, and thus no problem occurs. If, however,
their constituent materials are different, their thermal expansion
coefficients are also different. The thermal expansion difference
between the susceptor 2 and the guide ring 4 which are exposed to
high temperatures up to, e.g., about 800.degree. C. exceeds an
allowable value. As a result, the guide ring 4 may loosen or
break.
[0008] As the wafer size increases to 8", and 12", the sizes of the
susceptor 2 and the guide ring 4 also increase, and a slight
difference in thermal expansion coefficient results in a large
thermal expansion difference.
[0009] In recent years, in a plasma processing apparatus, it has
been contemplated to use an alloy with high conductivity and
excellent corrosion resistance for the susceptor itself in order to
improve the uniformity of the plasma density by suppressing the
potential difference within the support surface and the potential
difference between the susceptor and the side wall of the chamber.
In this case, however, the difference in thermal expansion
coefficient between the alloy and the ceramic material forming the
guide ring 4 becomes very large, and the guide ring may loosen or
break, as described above.
[0010] In this case, the guide ring itself may be made of the same
alloy material as that of the susceptor 2. However, since the
thickness of the guide ring 4 is as small as, e.g., about 1 mm, if
the guide ring 4 is made of an alloy material inferior in rigidity
to the ceramic material, it thermally deforms and cannot stand
practical use. Thus, such material is practically not employed.
[0011] The guide ring 4 is freely rotatable in the circumferential
direction of the susceptor 2. For this reason, when, for example,
the guide ring 4 is dismounted from the susceptor 2 for the purpose
of maintenance, the guide ring 4 is very difficult to precisely
mount back into its place.
BRIEF SUMMARY OF THE INVENTION
[0012] It is an object of the present invention to provide a
processing apparatus having an aligning ring member which neither
breaks nor is misaligned even if the ring member is formed of a
material with a thermal expansion coefficient different from that
of a susceptor.
[0013] According to an aspect of the present invention, there is
provided a processing apparatus comprising
[0014] a processing chamber,
[0015] a susceptor which is placed in the processing chamber and
has one surface with a support area on which a processing object is
set,
[0016] processing means for processing the processing object set on
the support area,
[0017] an aligning ring member which is arranged on the surface of
the susceptor so as to surround the support area, and defines
movement of the processing object placed on the support area along
the surface, and
[0018] movement regulating means, provided to the aligning ring
member and the susceptor, for permitting relative movement of the
aligning ring member and the susceptor in a radial direction due to
thermal expansion/contraction difference of the alignment ring
member and the susceptor while prohibiting relative rotation
thereof.
[0019] In this processing apparatus, even if the temperatures of
the susceptor and the ring member change upon repeat processing for
processing objects, and a thermal expansion difference is generated
between the susceptor and the ring member, the
expansion/contraction amount is absorbed by the movement regulating
means. Therefore, the aligning ring member can be prevented from
receiving excessive stress and breaking, and in addition from
loosening.
[0020] Further, the aligning ring member itself can be aligned with
the susceptor.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0021] FIG. 1 is a view schematically showing a processing
apparatus according to an embodiment of the present invention;
[0022] FIG. 2 is a plan view showing a susceptor and an aligning
ring member in the processing apparatus shown in FIG. 1;
[0023] FIG. 3 is a view showing both the aligning ring member and
the susceptor before the aligning ring member is mounted on the
susceptor;
[0024] FIG. 4 is a view showing the aligning ring member and the
susceptor upon the mounting;
[0025] FIG. 5 is a plan view showing the susceptor on which another
aligning ring member corresponding to a processing object with a
different size is mounted;
[0026] FIG. 6 is a plan view showing the susceptor on which an
aligning ring member having an orientation flat portion is
mounted;
[0027] FIG. 7 is a plan view showing a modification of the
susceptor according to the present invention;
[0028] FIG. 8 is a view showing the modification of the aligning
ring member and the susceptor according to the present
invention;
[0029] FIG. 9 is a plan view showing a modification of the ring
member;
[0030] FIG. 10 is a view showing a susceptor on which a
conventional guide ring is mounted; and
[0031] FIG. 11 is a plan view showing the susceptor on which a
conventional guide ring is mounted.
DETAILED DESCRIPTION OF THE INVENTION
[0032] A processing apparatus according to an embodiment of the
present invention will be described in detail below by exemplifying
a plasma film forming apparatus with reference to FIGS. 1 to 4.
[0033] As shown in FIG. 1, a plasma film forming apparatus 6
comprises a cylindrical processing chamber 8, which is grounded. A
plurality of exhaust ports 12 for evacuating the interior of the
chamber are formed in a bottom wall 10 of the processing chamber 8.
An exhaust system 16 is connected to these exhaust ports 12 through
a pump 14 to uniformly evacuate the interior of the processing
chamber 8 from a portion around the bottom wall. A disk-like
susceptor 20 is set in the processing chamber 8 through a plurality
of, e.g., three columns 18 made of a conductive material. A
processing object, e.g., a semiconductor wafer W can be placed on a
support area of an upper surface, i.e., support surface of the
susceptor 20. In this preferred embodiment, the upper surface of
the susceptor 20 is horizontal, but may be inclined. The susceptor
20 also serves as a lower electrode and is made up of a lower
susceptor 20A directly supported by the columns 18 and an upper
susceptor 20B joined to the upper surface of the lower susceptor
20A. The joined surface between the lower and upper susceptors 20A
and 20B is recessed, and a resistance heater 22 is fitted in the
recessed portion. The lower and upper susceptors 20A and 20B are
joined by, e.g., welding at the joined surface.
[0034] The susceptor 20, i.e., the lower and upper susceptors 20A
and 20B are made of an alloy containing, e.g., 20% to 23% of Cr, 12
to 15% of Mo, 2 to 4% of W, 2 to 6% of Fe, and the balance of Ni
and impurities. Components of impurities are 2.5% or less of Co,
0.08% or less of Si, 0.5% or less of Mn, and 0.015% or less of C.
Such an alloy material is generally commercially available as
Hastelloy (trademark). The entire susceptor may be formed using,
e.g., this Hastelloy. This alloy material has relatively high
conductivity and high corrosion resistance against ClF-based gas
used as cleaning gas.
[0035] A plurality of pin holes 24, e.g., three pin holes located
at, e.g., the vertexes of a regular triangle are formed in the
susceptor 20 to vertically extend through it. A lifter pin 26
vertically retractable from the susceptor 20 is inserted in each
pin hole 24. These lifter pins 26 are moved up/down by an elevator
mechanism (not shown) so as to support the lower surface of the
wafer by the upper ends of the three lifter pins 26 in
loading/unloading the wafer W.
[0036] An aligning circle ring member 28 is provided on the
peripheral portion of the upper surface of the susceptor 20. More
specifically, as shown in FIGS. 2 to 4, the aligning ring member 28
is a ring-like thin flat member set on the upper surface of the
susceptor so as to surround the semiconductor wafer W to be placed
on the support area of the susceptor. This ring member is formed of
a nonmetallic material, e.g., a ceramic material which has a
thermal expansion coefficient greatly different from (smaller than)
that of the alloy forming the susceptor 20, and is excellent in
heat resistance and rigidity.
[0037] Examples of such a ceramic material are aluminum oxide
(Al.sub.2O.sub.3) and aluminum nitride (AlN). In addition, silicon
compounds such as SiC and SiO.sub.2 are also available.
[0038] A plurality of, e.g., four movement regulating mechanisms 30
(FIG. 2) for safely permitting thermal expansion/contraction of the
aligning ring member 28 and prohibiting the circumferential
movement of the aligning ring member 28 while associating the
aligning ring member 28 with the susceptor 20 are mounted to have
equal intervals (an angle of 90.degree. in the illustrated example)
in the circumferential direction of the aligning ring member
28.
[0039] Each movement regulating mechanism 30 includes a movement
allowing elongated hole or slit 32 which is formed in the aligning
ring member 28 and extends in the radial direction of the circular
ring member 28 and thus the susceptor 20, and a columnar susceptor
side movement regulating projection 34 vertically projecting from
the upper peripheral edge portion (around the support area) of the
susceptor 20. The diameter of the regulating projection 34 is
smaller than a width L3 (FIG. 2) of the elongated hole 32 so as to
enable insertion of the regulating projection 34 in the elongated
hole 32 serving as a guide. However, the diameter of the regulating
projection 34 is set only slightly smaller than the width L3 of the
elongated hole 32 so as to prevent circumferential movement of the
ring member 28 on the susceptor 20, and to permit the projection 34
to relatively move within the elongated hole 32 in the radial
direction of the aligning ring member 28, i.e., guide the
projection 34 along the elongated hole. The projection 34 may be
formed integrally with the susceptor 20, or formed separately and
attached to the susceptor. In the latter case, the projection may
be made up the same or different material against the susceptor.
The elongated hole 32 has a length L4 large enough to absorb the
thermal expansion difference between the susceptor 20 and the
aligning ring member 28, e.g., a length of about 5 mm. With this
setting, the thermal expansion difference in the radial direction
between the susceptor and the ring member which is generated upon a
change in temperature can be absorbed. In the embodiment shown in
FIG. 2, the projection 34 is located at almost the center of the
elongated hole 32 in the longitudinal direction in consideration of
not only heating but also cooling of the susceptor 20. If the
susceptor 20 is only heated during processing, the projection 34 is
preferably inserted in the elongated hole so as to be located near
the end portion of the elongated hole 32 on the inner side of the
ring member in the longitudinal direction. To the contrary, if the
susceptor 20 is only cooled during processing, or the thermal
expansion coefficient of the susceptor is smaller than that of the
ring member though the susceptor 20 is heated, the projection 34 is
inserted in the elongated hole 32 so as to be located near the end
portion of the elongated hole 32 on the outer side of the ring
member in the longitudinal direction.
[0040] As shown in FIG. 2, an inner diameter L5 of the ring member
28 is set larger than a diameter L2 of the wafer W by about 1 mm,
so that the wafer can be aligned with precision of .+-.1 mm. When,
therefore, the wafer W is located at the center of the ring member
28 with high precision, the gap between the peripheral portion of
the wafer and the inner circumferential portion of the ring member
28 is about 0.5 mm except for the orientation flat portion. As
shown in FIG. 3, a thickness L6 of the wafer W is, e.g., about 0.8
mm, whereas a thickness L7 of the ring member 28 is, e.g., about
1.5 mm. Both the wafer W and the ring member 28 are made very
thin.
[0041] As shown in FIG. 1, an upper wall 38 on which a shower head
36 serving as an upper electrode is mounted integrally or
detachably, is airtightly attached to the circumferential wall of
the processing chamber 8 through an insulating ring 40 at the
ceiling portion of the chamber 8. The shower head 36 has a
cylindrical shape with a lower surface facing nearly the entire
upper surface of the susceptor 20. The shower head 36 and the
susceptor 20 define a processing space S between them. The shower
head 36 showers various gases in the processing space S. A spray
surface 42 as the lower surface of the shower head 36 has many
spray holes 44 for spraying gas. A diffusion plate 48 having many
diffusion holes 46 is horizontally arranged inside the shower head
36 to diffuse gas within the head. The circumferential wall of the
shower head 36 incorporates a head temperature control jacket 66
for selectively flowing, e.g., a cooled or heated heat transfer
medium, as needed, in order to control the temperature of the wall
surface.
[0042] A gas inlet port 50 for introducing gas into the head is
formed at the center of the upper portion of the shower head 36. A
supply path 52 for supplying gas is connected to the gas inlet port
50. Various gas sources (not shown) are connected to the supply
path 52. For example, TiCl.sub.4 gas and H.sub.2 gas are used as Ti
film forming gas, Ar gas is used as plasma gas, and ClF-based gas
such as ClF.sub.3 gas is used as cleaning gas.
[0043] A matching circuit 56 and an RF power supply 58 of, e.g., a
13.56 MHz are connected to the upper wall 38 through a lead 54 in
order to generate a plasma in the processing spaces, e.g., forming
a Ti film.
[0044] The circumferential wall of the processing chamber 8
incorporates a chamber temperature control jacket 60 for
selectively flowing, e.g., a cooled or heated heat transfer medium,
as needed, in order to control the temperature of the wall surface.
A gate valve 62 which opens/closes in loading/unloading a wafer is
formed in the circumferential wall of the chamber, and a load-lock
chamber 64 is connected to the chamber through the valve 62.
[0045] The operation of the apparatus having the above arrangement
will be explained in relation with formation of a Ti film as an
example of film forming operation.
[0046] The wafer W in the load-lock chamber 64 is loaded by a
convey arm (not shown) into the processing chamber 8 through the
opened gate valve 62, and transferred on to the top ends of the
lifter pins 26 having moved up from under the susceptor 20. Upon
the transfer, the lifter pins 26 are moved down to place the wafer
surrounded by the aligning ring member 28 on the support area of
the upper surface of the susceptor 20. At this time, even if the
wafer W is obliquely placed on the support surface due to some
reason and slides on the support surface, the movement of the wafer
W is regulated by the aligning ring member 28 arranged at the
peripheral edge portion of the susceptor 20. Therefore, the wafer
can be aligned with high alignment precision.
[0047] After the wafer W has been placed, TiCl.sub.4 gas and
H.sub.2 gas as film forming gas, and Ar gas as plasma gas are
respectively supplied into the processing chamber 8 through the
shower head 36 at predetermined flow rates. The interior of the
processing chamber 8 is evacuated by the pump 14 to maintain the
chamber interior in a predetermined low-pressure state.
[0048] At the same time, an RF power of 13.56 MHz is applied from
the RF power supply 58 to the shower head 36 serving as an upper
electrode to apply an RF electric field between the shower head 36
and the susceptor 20 serving as a lower electrode. As a result, the
Ar gas is excited into a plasma to promote reduction of the
TiCl.sub.4 gas and the H.sub.2 gas, thereby forming a Ti film on
the wafer surface.
[0049] During the formation of the film, the wafer W is heated to a
predetermined temperature by the resistance heater 22 buried in the
susceptor 20. The circumferential wall of the processing chamber 8
and the shower head 36 which are easily heated in a high
temperature by the plasma are cooled to predetermined temperatures
by flowing refrigerants through their jackets 60 and 66.
[0050] At this time, the processing is performed under the
conditions: the temperature of the wafer: about 700.degree. C., the
temperature of the circumferential wall of the chamber: about
130.degree. C., the temperature of the shower head 36: about
130.degree. C., the process pressure: about 1 Torr, and the RF
power: about 700 W.
[0051] In this way, a film is formed using the conductive susceptor
20 made of an alloy such as Hastelloy (trademark). Thus, the
susceptor 20 and the circumferential wall of the chamber are kept
at almost the same potential. Consequently, the plasma density in
the processing space S becomes approximately uniform. This enables
plasma CVD film formation of the Ti film without any charge-up
damage to many elements formed on the surface of the wafer.
[0052] In this film forming operation, since the wafer is heated to
about 700.degree. C., as described above, the susceptor 20 and the
aligning ring member 28 located at the upper peripheral edge
portion of the susceptor 20 are also heated to about 700.degree.
C., and a very large thermal expansion difference of, e.g., about 2
mm is generated between the two members owing to the difference in
thermal expansion coefficient between them. Since the susceptor 20
made of an alloy has a larger thermal expansion coefficient than
that of the ring member 28 made of a ceramic material, a much
larger expansion force radially acts on the susceptor 20 than on
the ring member 28. At this time, the susceptor side movement
regulating projection 34 projecting from the upper surface of the
susceptor 20 can relatively move in the longitudinal direction
within the movement allowing elongated hole 32 formed in the ring
member 28 so that the susceptor 20 can radially expand with respect
to the ring member 28 to absorb the thermal expansion. Therefore,
the ring member 28 can be prevented from receiving large stress and
breaking.
[0053] In particular, the thermal expansion difference between the
ring member 28 made of a ceramic material and the susceptor 20 made
of an alloy becomes large at a processing temperature of
700.degree. C. By setting the length L4 of the elongated hole 32
sufficiently large, thermal expansion/contraction can be
satisfactorily absorbed even if the temperature is repeatedly
increased/decreased. The ring member 28 can be prevented from
receiving stress and breaking.
[0054] Since the width L3 of the elongated hole 32 is set slightly
larger than the diameter of the movement regulating projection 34,
the ring member 28 is prevented from relatively moving in the
circumferential direction of the susceptor 20 by thermal
contraction, and the circumferential movement of the ring member 28
can be regulated. Therefore, the ring member 28 itself is hardly
loosed, the wafer W is not misaligned, and the alignment precision
of the wafer W does not decrease.
[0055] When, e.g., a high-rigidity ceramic material is used for the
ring member 28, the ring member 28 does not thermally deform even
if the thickness L7 of the ring member 28 is as small as, e.g.,
about 1.5 mm.
[0056] Further, in remounting the ring member 28 on to the
susceptor 20 after dismounting it for the purpose of maintenance,
the ring member 28 itself can be aligned with the susceptor 20 by
fitting the regulating projections 34 in the original corresponding
elongated holes 32.
[0057] In the above embodiment, although the movement allowing
elongated hole of the movement regulating mechanism is formed as a
through hole which allows the regulating projection to extend
therethrough, this elongated hole may be formed as a blind hole,
i.e., groove which does not allow the regulating projection to
extend therethrough.
[0058] FIG. 5 shows an aligning ring member 28 having an inner
diameter L8 different from, e.g., smaller than the inner diameter
L5 of the ring member 28 shown in FIG. 2. If a plurality of
aligning ring members having different inner diameters are prepared
in correspondence with various wafer sizes, the processing
apparatus can be easily applied to any wafers with different sizes
such as 12", 8", and 6" wafers by only exchanging the aligning ring
member 28.
[0059] In general, the wafer W has an orientation portion for
orientating the wafer W, i.e., an orientation flat 68 (or notch).
As shown in FIG. 6, the aligning ring member 28 may also comprise a
corresponding portion such as an orientation flat portion 70 (or a
projection of a shape complemental with the notch) in
correspondence with the orientation flat 68 (or notch). This
corresponding or complemental portion also contributes to the
alignment of the wafer W, resulting in higher alignment precision.
In this case, if the ring member 28 is remounted on the susceptor
20 with reference to the orientation flat portion 70 upon
maintenance, the ring member 28 can be easily reset at the original
position, i.e., not a position where the ring member 28 is located
upon circumferential rotation but the original position. In this
manner, the inner circumferential surface of the ring member 28 of
the present invention desirably has a shape conforming to the outer
peripheral shape of the processing object at a predetermined small
gap over almost the entire periphery, i.e., a complementary shape.
The ring member is not limited to a circular shape, and may be
formed into another shape, e.g., a rectangular shape for a
rectangular processing object such as an LCD substrate. In this
case, the radial direction means a direction not extending along
the ring member, for example, a direction toward a gravity center
of the rectangular ring member.
[0060] The above embodiment has exemplified the case wherein, as
the movement regulating mechanism 30, the elongated hole 32 is
formed on the ring member 28 side, and the projection 34 is formed
on the susceptor 20 side. Alternatively, they may be formed on
reverse sides, as shown in FIGS. 7 and 8. As shown in FIG. 8, a
ring member side movement regulating projection 74 of the movement
regulating mechanism 30 may be formed on the lower surface of the
aligning ring member 28. In correspondence with this, a movement
allowing elongated groove 76 having the same width and length as
those of the above elongated hole 32 may be formed at the
peripheral edge portion (around the support area) of the upper
surface of the susceptor 20 so as to extend in the radial direction
of the susceptor 20, as shown in FIG. 7.
[0061] With this arrangement, the same effects as those described
above can be obtained. In addition, since no projection need be
arranged on the surface of the susceptor 20, the manufacture of the
susceptor 20 can be facilitated.
[0062] In the above embodiment, the movement regulating mechanism
is made up of the movement allowing elongated hole 32 and the
regulating projection 34. The present invention is not limited to
this, and the movement regulating mechanism suffices to prevent the
relative movement of the ring member on the upper surface of the
susceptor in the circumferential direction or the direction along
the ring member of the susceptor, and to permit the radial movement
of the ring member. For example, instead of the movement allowing
elongated hole, a pair of guide convex members or ridges extending
radially which radially movably receive the regulating projection
between them may be arranged at an interval slightly larger than
the width of the regulating projection on either one of the
aligning ring and the susceptor where no regulating projection is
formed. The regulating projection is not limited to a circular
columnar shape (circular crossection) and may have another shape
such as a quadrangular prism (rectangular crossection).
[0063] The above embodiment concerns with the case of arranging
four movement regulating mechanisms 30. The number of movement
regulating mechanisms 30 may however be arbitrarily set as far as
it is two or more. Although these movement regulating mechanisms
are preferably circumferentially arranged on the ring member
(susceptor) at equal intervals, e.g., 180.degree. for two
mechanisms or 120.degree. for three mechanisms, they need not be
always arranged at equal intervals. A modification of a ring member
28 of a simple construction having two movement regulating holes 32
is shown in FIG. 9. Two holes 32 are arranged at interval of
180.degree., one of which is a slot extending in a radial direction
of the ring member 28 for allowing a relative movement of a
projection inserted in the slot,-and the other of which is a
circular hole having a diameter slightly smaller than that of the
projection inserted in the circular hole. Thus, the circular hole
32 does not permit the relative movement of the projection inserted
in the circular hole in the radial direction. Hence, the distance
the susceptor and the ring member can move relative to each other
due to thermal expansion/contraction difference is only half the
distance they can so move if both hole are elongate. Nevertheless,
the function of the movement regulating mechanism may by
practically attained, in this modification. Similarly, in the case
of using two slots or elongated holes, one of two projections is
formed to have a crossection similar to the slot. The above
embodiment has exemplified a single wafer processing apparatus in
which one aligning ring member is disposed on the susceptor to
process processing objects one by one. Alternatively, a plurality
of aligning ring members may be set on one susceptor to process a
plurality of processing objects at once.
[0064] As the metal for the susceptor 20, Hastelloy is used, but
another metal such as molybdenum, nickel, or Inconel (trademark),
or the same metal as that for a conventional susceptor such as AlN
or Al.sub.2O.sub.3 may be used.
[0065] Although the above embodiment is directed to a plasma CVD
film forming apparatus, the present invention is not limited to
this and is applicable to another processing apparatus such as a
thermal CVD film forming apparatus, an etching apparatus, a
sputtering apparatus, or an ashing apparatus.
[0066] The processing object is not limited to a semiconductor
wafer but may be a glass substrate, an LCD substrate, or the
like.
[0067] As has been described above, the processing apparatus of the
present invention yields the following good effects.
[0068] Since the aligning ring member is placed on the susceptor
via the movement regulating mechanism, even when a thermal
expansion difference is generated between the susceptor and the
ring member with a change in temperature of the processing object,
this thermal expansion difference can be absorbed without
decreasing the alignment precision. Therefore, the ring member can
be prevented from receiving excessive stress generated by the
thermal expansion difference and breaking. In addition, the ring
member itself can be prevented from loosening.
[0069] Particularly, when the susceptor and the ring member are
formed of different materials having different thermal expansion
coefficients, e.g., the susceptor is formed of a metal, and the
ring member is formed of a ceramic material, the breakage
prevention effect and the like can be enhanced.
* * * * *