Cassette chamber

A cassette chamber according to the present invention comprises a housing defining a space stored with a cassette for holding a plurality of objects of treatment, a lift base having a rotatable shaft and located in the housing for up-and-down motion, an auxiliary base fixed to the shaft and inclined at a predetermined angle to the longitudinal direction of the shaft, a cassette support having a bottom support portion set on the lift base and bearing the bottom face of the cassette and a back support portion rotatably supported by the auxiliary base and bearing the back face of the cassette, a rotation mechanism for rotating the shaft as the lift base ascends or descends, thereby rotating the auxiliary base and the cassette support between a first position inside the housing and a second position outside the housing, and a support section for keeping the back support portion of the cassette support parallel to the shaft by engaging the back support portion being rotated to the second position by the rotation mechanism and causing the back support portion to rotate relatively to the auxiliary base.

BACKGROUND OF THE INVENTION 
The present invention relates to a cassette chamber into and from which a 
cassette stored with objects of treatment, such as semiconductor wafers, 
is loaded and unloaded. 
Generally, in subjecting semiconductor wafers to any of various treatments, 
such as film formation, etching, thermal oxidation, etc., a cassette 
stored with a large number of wafers, e.g., 25 wafers, is first loaded 
into a cassette chamber. Thereafter, each wafer in the cassette is 
delivered into a process chamber through a transfer chamber by means of a 
transportation arm in a vacuum. 
In setting the cassette in the cassette chamber, the cassette is placed on 
a stage in the chamber in a manner such that its wafer loading/unloading 
aperture faces upward. Thereafter, the cassette is rotated substantially 
through 90.degree. by means of a drawbridge-type drive mechanism in the 
cassette chamber as it is taken into the chamber, and the wafer 
loading/unloading aperture having so far been kept upward is oriented in 
the horizontal direction. 
In general, a plurality of cassette chambers, e.g., two chambers, are 
connected to one transfer chamber that is provided with one transportation 
arm. Accordingly, each of cassettes in the two cassette chambers is 
directed so that its horizontally oriented wafer loading/unloading 
aperture is reoriented in the moving direction of the transportation arm, 
whereby the single arm can access the individual cassettes in the two 
chambers. 
FIG. 23 shows a cluster tool apparatus, in which semiconductor wafers W are 
fed into process chambers and treated therein by the aforesaid series of 
processes of operation. This apparatus mainly comprises two process 
chambers 2 and 4, one transfer chamber 6 connected to the chambers 2 and 
4, and two cassette chambers 8 and 10 connected to the chamber 6. These 
chambers can communicate with one another by means of gate valves G that 
can be closed airtightly. As shown in FIG. 24, the transfer chamber 6 
contains therein a bendable rotatable transportation arm 12 of, for 
example, a multi-joint type, which can load and unload semiconductor 
wafers W stored in cassettes C in the cassette chambers 8 and 10. 
In general, each cassette C must be placed on a stage outside a gate door 
G1 of each corresponding cassette chamber 8 or 10 in a manner such that it 
faces itself in the X-axis direction of FIG. 23 and that its wafer 
loading/unloading aperture 14 faces upward (or in the Z-axis direction). 
In order to take the cassettes C into the cassette chambers 8 and 10 and 
take out the semiconductor wafers W from the cassettes C in the two 
cassette chambers 8 and 10 by means of the single transportation arm 12, 
therefore, each cassette C must be rotated horizontally while being set 
upright so that the wafer loading/unloading aperture 14 is directed toward 
the center of the transportation arm 12 (or oriented in a moving direction 
A). 
Apparatuses for this operation are described in, for example, U.S. Pat. 
Nos. 5,186,594 and 5,507,614. In the apparatus disclosed in U.S. Pat. No. 
5,186,594, the cassette C placed on the stage outside the cassette chamber 
8, with its wafer loading/unloading aperture 14 upward, is rotated through 
90.degree. around the Y-axis of FIG. 23 by means of a drawbridge-type 
drive mechanism. Thereupon, the cassette C is taken into the chamber 8, 
and its aperture 14, having so far been kept upward (or in the Z-axis 
direction), is reoriented in the horizontal direction (X-axis direction). 
Then, the cassette C is rotated through a predetermined angle .theta. 
around the Z-axis of FIG. 23 by means of a pivot mechanism, whereupon its 
wafer loading/unloading aperture 14 is directed toward the center of the 
arm 12 (see FIG. 25). In the apparatus disclosed in U.S. Pat. No. 
5,507,614, on the other hand, a tilted shaft that is oriented at a 
predetermined angle to the direction of gravity is rotated so that the 
cassette C can be situated at one operation in a predetermined position 
with its aperture 14 directed toward the center of the arm 12. 
The apparatus stated in U.S. Pat. No. 5,186,594 requires the pivot 
mechanism as well as the drawbridge-type drive mechanism, that is, it 
needs use of separate drive mechanisms for rotating the cassette C through 
90.degree. around the Y-axis and through the predetermined angle around 
the Z-axis. Consequently, a lot of complicated drive mechanisms must be 
used in each cassette chamber, so that the manufacturing cost is high, and 
more particles are produced. As for the apparatus described in U.S. Pat. 
No. 5,507,614, it is designed so that the obliquely extending shaft is 
rotated. As compared with the case in which the cassette is rotated 
horizontally, therefore, the rotation mechanism section of this apparatus 
includes more biased portions, so that more particles are produced 
correspondingly. Since the cassette C is rotated obliquely, moreover, the 
rotation requires a wide space, so that the chamber is inevitably 
large-sized. 
BRIEF SUMMARY OF THE INVENTION 
The object of the present invention is to provide a cassette chamber of 
simple construction, which is provided with a drive mechanism capable of 
loading a horizontally oriented cassette into the chamber while setting it 
upright and orienting a wafer loading/unloading aperture of the cassette 
in the access direction of a transportation arm. 
The above object of the present invention is achieved by a cassette 
chamber, which comprises: a housing defining a space stored with a 
cassette for holding a plurality of objects of treatment; a lift base 
having a rotatable shaft and located in the housing for up-and-down 
motion; an auxiliary base fixed to the shaft and inclined at a 
predetermined angle to the longitudinal direction of the shaft; a cassette 
support having a bottom support portion set on the lift base and bearing 
the bottom face of the cassette and a back support portion rockably 
supported by the auxiliary base and bearing the back face of the cassette; 
a rotation mechanism for rotating the shaft as the lift base ascends or 
descends, thereby rotating the auxiliary base and the cassette support 
between a first position inside the housing and a second position outside 
the housing; and a support section for keeping the back support portion of 
the cassette support parallel to the shaft by engaging the back support 
portion being rotated to the second position by the rotation mechanism and 
causing the back support portion to rock relatively to the auxiliary base. 
Additional objects and advantages of the invention will be set forth in the 
description which follows, and in part will be obvious from the 
description, or may be learned by practice of the invention. The objects 
and advantages of the invention may be realized and obtained by means of 
the instrumentalities and combinations particularly pointed out in the 
appended claims.

DETAILED DESCRIPTION OF THE INVENTION 
Preferred embodiments of a cassette chamber according to the present 
invention will now be described with reference to the accompanying 
drawings. 
FIGS. 1 to 6 show a cassette chamber 8 according to a first embodiment of 
the invention. The chamber 8 according to present embodiment, like the 
cassette chamber 8 of the cluster tool apparatus shown in FIGS. 23 and 24, 
is connected to a transfer chamber 6 having a transportation arm 12. 
As shown in FIG. 1, the cassette chamber 8 of the present embodiment 
includes a rectangular chamber vessel 18 of, e.g., aluminum. The vessel 18 
is provided with a cassette loading aperture 20 in one side face thereof, 
through which a cassette C can be passed. As shown in FIG. 23, the 
aperture 20 is closed by an open-close gate door G1 (not shown in FIG. 1). 
A wafer unloading aperture 22 is formed in the upper part of the other 
side face of the vessel 18. The aperture 22 is connected to the transfer 
chamber 6 by means of an open-close gate valve G. As shown in FIG. 4, the 
cassette loading aperture 20 opens in the X-axis direction, while the 
wafer unloading aperture 22 opens in a direction at a predetermined angle 
.theta. (e.g., 22.5.degree.) to the X-axis direction, that is, an access 
direction A in which the transportation arm 12 in the transfer chamber 6 
accesses the cassette chamber 8. The cassette C can store, for example, 25 
semiconductor wafers W therein. As shown in FIG. 7, moreover, the cassette 
C has a wafer loading/unloading aperture 14 through which the wafers W are 
loaded and unloaded, and that side face of the cassette C which is 
opposite to the aperture 14 is formed as a back face 24. Further, the 
cassette C has a top face 28, which is provided with a handle 26, and a 
bottom face 30. 
As shown in FIG. 1, a lift pedestal 32 is provided in the chamber vessel 
18. A lift rod 34 is connected to the underside of the pedestal 32. The 
rod 34 air-tightly penetrates a bottom portion 18A of the vessel 18 with 
the aid of a seal 36, such as an O-ring, and is moved up and down by means 
of a lift mechanism 38. 
As shown in detail in FIGS. 4 and 6, a main shaft 40 is rotatably supported 
on one side portion of the lift pedestal 32 near the cassette loading 
aperture 20 by means of two bearings 46. Pinion gears 48, which constitute 
part of a rotation mechanism 54 (mentioned later), are fixed individually 
to the opposite ends of the shaft 40. Preferably, the gears 48 are formed 
of a resin having relatively high hardness, in order to restrain 
production of particles. 
The main shaft 40 is fitted with an auxiliary pedestal 42, which extends 
vertically (in the Z-axis direction), by means of two arms 50A and 50B. In 
this case, one end of each of the arms 50A and 50B is fixed to the shaft 
40, while the other end thereof is fixed to, for example, a lower region 
of the auxiliary pedestal 42. Thus, the pedestal 42 can be rotated 
integrally with the shaft 40 so that it projects outside the chamber 8. 
The first arm 50A is made to be a little longer than the second arm 50B so 
that the auxiliary pedestal 42 faces in the access direction (moving 
direction) A of the transportation arm 12 at the predetermined angle 
.theta. (e.g., 22.5.degree.) to the longitudinal direction (Y-axis 
direction) of the shaft 40. 
An L-shaped cassette support 44, which extends beyond the other side 
portion of the auxiliary pedestal 42, is attached to one side portion of 
the pedestal 42 by means of a hinge 52. The support 44 is composed of a 
bottom support portion 44A for bearing and holding the bottom face 30 of 
the cassette C and a back support portion 44B for bearing and holding the 
back face 24 of the cassette. The back support portion 44B is bonded to 
the bottom support portion 44A at right angles thereto, and its one side 
portion is attached to the one side portion of the auxiliary pedestal 42 
by means of the hinge 52. The hinge 52 is provided with an elastic member, 
such as a spring, which continually urges the back support portion 44B to 
engage the pedestal 42. Normally, therefore, the back support portion 44B 
is caused, by means of the urging force of the elastic member, to engage 
(abut against) the pedestal 42 and face in the access direction A of the 
transportation arm 12. Only when it is subjected to a force that resists 
the urging force of the elastic member, the support portion 44B rotates 
around the hinge 52 and is disengaged (away) from the auxiliary pedestal 
42. 
As is clearly shown in FIGS. 1 and 4, two stationary racks 56 are set up 
vertically on the bottom portion 18A of the chamber vessel 18, in 
positions where they can mesh with their corresponding pinion gears 48. 
Preferably, the racks 56 are formed of a resin having relatively high 
hardness, in order to restrain production of particles. 
The stationary racks 56, along with the pinion gears 48, constitute the 
rotation mechanism 54 for rotating the cassette support 44. The racks 56 
mesh with their corresponding gears 48 that ascend and descend as the lift 
rod 34 moves up and down. As the gears 48 are rotated, the main shaft 40 
is rotated, and the cassette support 44, which is fixed to the shaft 40 by 
means of the auxiliary pedestal 42, is rotated. More specifically, the 
racks 56 have their tooth shape and height set so that they can rotate the 
pinion gears 48 through 90.degree., and moreover, can rotate the 
descending and ascending gears 48 in the counterclockwise and clockwise 
directions of FIG. 1, respectively. Thus, when the lift pedestal 32 
descends, the rotation mechanism 54 rotates the cassette support 44 
through 90.degree. in the counterclockwise direction, thereby causing it 
to project outward from the cassette chamber 8 through the cassette 
loading aperture 20. When the pedestal 32 ascends, the mechanism 54 
rotates the support 44 through 90.degree. in the clockwise direction, 
thereby situating it inside the chamber 8. 
Further, a support member 58 is set up vertically on the bottom portion 18A 
of the chamber vessel 18. The support member 58 engages the free end side 
of the back support portion 44B of the cassette support 44, which rotates 
so as to project outward from the cassette loading aperture 20, and causes 
the support portion 44B to rotate around the hinge 52, resisting the 
urging force of the elastic member attached to the hinge 52, whereupon the 
support portion 44B is disengaged from the auxiliary pedestal 42. More 
specifically, the height of the support member 58 is set so that the back 
support portion 44B is kept horizontal when the cassette support 44 is 
rotated through 90.degree. in the counterclockwise direction around the 
main shaft 40, as shown in FIGS. 3 and 5. 
In order to position the cassette support 44 with respect to the lift 
pedestal 32, the pedestal 32 is provided with a projection 60 on its upper 
surface, while the bottom support portion 44A has a recess 62 on its lower 
surface (see FIG. 1). The projection 60 can be fitted in the recess 62. 
The following is a description of the operation of the cassette chamber 8 
constructed in this manner. 
FIGS. 1 and 4 show a state in which the cassette C, holding the 
semiconductor wafers W therein, is located in a wafer delivery position in 
the upper part of the chamber vessel 18. In this state, the cassette 
support 44 is caused to abut against the auxiliary pedestal 42 by the 
urging force of the elastic member, and is oriented in the access 
direction (moving direction) A of the transportation arm 12 (or is 
directed at the predetermined angle .theta. to the X-axis direction). 
Thus, the wafer loading/unloading aperture 14 of the cassette C placed on 
the cassette support 44 is opposed to the wafer unloading aperture 22 of 
the chamber vessel 18, and is also oriented in the access direction A of 
the arm 12 in the transfer chamber 6. In this state, moreover, the load of 
the cassette C is borne by the bottom support portion 44A of the cassette 
support 44. 
In discharging (unloading) the cassette C in the state of FIG. 1 from the 
chamber vessel 18, the lift rod 34 is first moved downward to lower the 
lift pedestal 32. When the pedestal 32 is lowered to a predetermined 
height, the pinion gears 48, fixed individually to the opposite ends of 
the main shaft 40, mesh with the teeth of the stationary racks 56 that are 
set up on the bottom portion 18A of the vessel 18 (see FIG. 2). When the 
lift pedestal 32 is further lowered with the gears 48 and the racks 56 in 
mesh with one another, the gears 48 rotate in the counterclockwise 
direction of FIG. 1 as they descend along their corresponding racks 56. 
Also, the main shaft 40, which is integral with the pinion gears 48, 
descends rotating counterclockwise. Accordingly, the auxiliary pedestal 
42, which is fixed to the shaft 40 by means of the arms 50A and 50B, and 
the cassette support 44 also descend rotating counterclockwise, whereupon 
the wafer loading/unloading aperture 14 of the cassette C, having so far 
been oriented in the horizontal direction, starts gradually to turn 
upward. 
When the cassette support 44 is lowered to a predetermined height while 
rotating counterclockwise in this manner, the cassette C, along with the 
support 44, projects outward from the chamber vessel 18 through the 
cassette loading aperture 20. At the same time, the upper end of the 
support member 58 abuts against the back of the free end side of the back 
support portion 44B of the support 44, thereby preventing the free end 
side of the back support portion 44B (support 44) from descending further. 
When the cassette support 44 in this state is further rotated, that is, 
when the auxiliary pedestal 42 is lowered rotating as the lift pedestal 32 
descends, the back support portion 44B, having so far been in contact with 
the pedestal 42, rotates around the hinge 52 and is disengaged from the 
pedestal 42. When the cassette support 44 is rotated counterclockwise 
through 90.degree., the descent of the lift pedestal 32 is stopped, and 
the support 44 is stopped from rotating further. FIGS. 3 and 5 show the 
resulting state. As shown in these drawings, the back support portion 44B 
projects outward from the chamber vessel 18 through the cassette loading 
aperture 20 in a manner such that it is kept horizontal by the holding 
action of the support member 58. Thus, the cassette C also projects 
outside the vessel 18, and its load is borne by the back support portion 
44B with the wafer loading/unloading aperture 14 facing upward (in the 
Z-axis direction). 
When the aforesaid operation is carried out reversely from the state shown 
in FIGS. 3 and 5, the cassette C is loaded into the chamber vessel 18, and 
the wafer loading/unloading aperture 14 is oriented in the access 
direction A of the transportation arm 12. When the lift pedestal 32 is 
raised from the state of FIGS. 3 and 5, the cassette support 44 is lifted 
rotating clockwise. Thereupon, the back support portion 44B and the 
support member 58 are disengaged from each other, and the support portion 
44B is brought into contact with the auxiliary pedestal 42. When the 
cassette support 44 in this state is further raised and rotated clockwise 
through 90.degree., it is set in the state shown in FIG. 2. When the lift 
pedestal 32 in this state is raised to a predetermined height, the 
cassette support 44 is oriented in the access direction (moving direction) 
A of the transportation arm 12. Thus, the wafer loading/unloading aperture 
14 of the cassette C placed on the support 44 is opposed to the wafer 
unloading aperture 22 of the chamber vessel 18, and is also oriented in 
the access direction A of the arm 12 in the transfer chamber 6. 
According to the cassette chamber 8 of the present embodiment, as described 
above, the cassette C, kept horizontal so that its wafer loading/unloading 
aperture 14 faces upward, can be set upright as it is loaded into the 
chamber 8 and moved to the wafer delivery position, by only moving the 
lift rod 34 upward. By only moving the rod 34 downward, on the other hand, 
the cassette C in the wafer delivery position can be unloaded from the 
cassette chamber 8 in a manner such that its aperture 14 upward. Thus, in 
the cassette chamber 8 of the present embodiment, the cassette support 44 
is oriented in the access direction A of the transportation arm 12, so 
that a drive mechanism need not be provided for orienting the cassette C 
in the access direction A of the arm 12. Accordingly, the number of drive 
mechanisms used in the chamber 8 can be reduced, so that production of 
particles can be restrained. In contrast with this, the apparatus 
described in U.S. Pat. No. 5,186,594 requires use of separate drive 
mechanisms for rotating the cassette C through 90.degree. around the 
Y-axis and through the predetermined angle around the Z-axis. According to 
this arrangement, therefore, a lot of complicated drive mechanisms must be 
used in each cassette chamber, so that the manufacturing cost is high, and 
more particles are produced. According to the cassette chamber 8 of the 
present embodiment that requires use of no drive mechanism for rotating 
the cassette C around the Z-axis, compared with the apparatus described in 
U.S. Pat. No. 5,186,594, the fewer drive mechanisms result in restrained 
production of particles, and the simple construction permits reduction in 
cost. 
Since the cassette chamber 8 of the present embodiment has no obliquely 
extending shaft, moreover, its rotation mechanism section includes no such 
biased portions as the tilted shaft described in U.S. Pat. No. 5,507,614, 
so that only small quantities of particles are produced. Since the 
cassette C need not be rotated around any diagonal axes, moreover, 
rotation requires only a small space, so that the chamber 8 can be 
manufactured with a compact design. 
The arrangement of the cassette chamber 8 according to the present 
embodiment is also applicable to a cassette chamber 10 that adjoins the 
cassette chamber 8. It is to be understood, in this case, that the 
respective lengths of arms 50A and 50B of the cassette chamber 10 are made 
to be opposite in superiority to those of the cassette chamber 8 and the 
hinge 52 is attached to the other side portion of the auxiliary pedestal 
42, in order to orient the cassette support 44 in the access direction A 
of the transportation arm 12. According to a modification of the present 
embodiment, moreover, the lift pedestal 32 has a space that can store a 
plurality of dummy wafers for inspection, for example. 
FIG. 8A shows a first modification of the support member. As shown in FIG. 
8A, this support member 58a has a rotatable spherical member 64 on its 
upper end. Preferably, the spherical member 64 is formed of a resin in 
order to restrain production of particles. With use of the rotatable 
spherical member 64, the coefficient of friction between the support 
member 58a and the back support portion 44B of the cassette support 44 is 
so low that production of particles can be further restrained. 
FIG. 8B shows a second modification of the support member. As shown in FIG. 
8B, this support member 58b has a rotating roller 64 on its upper end. 
Preferably, the roller 64 is formed of a resin, and its length is adjusted 
to about 3 cm, for example. Further, a rotating roller 66 is provided on 
the back of the back support portion 44B of the cassette support 44, in a 
region such that it can be in contact with the roller 64. In this case, 
the rollers 64 and 66 are arranged so as to cross each other at an angle 
of about 90.degree.. According to this arrangement, the coefficient of 
friction between the rollers 64 and 66 is so low that production of 
particles can be restrained. 
FIGS. 9A and 9B show a third modification 58c of the support member. 
Provided on the upper end of the support member 58c is a micro-switch 90 
for detecting the presence of a cassette C on the cassette support 44, at 
the unloading position. An optical sensor (not shown) is mounted on one 
side of the cassette chamber 8, for detecting the presence of a cassette C 
on the support 44, at the loading position. Two leaf springs 91A and 91B 
are provided on the bottom 44A and back 44B of the support 44, 
respectively. The leaf spring 91A has a projection 300. Two pins 92A and 
92B are provided on the bottom 44A and back 44B of the support 44, 
respectively. The pins 92A and 92B can project outwards to push the leaf 
springs 91A and 91B, respectively. 
When no cassette C is placed on the cassette support 44 as shown in FIG. 
9A, neither the pin 92A nor the pin 92B projects outwards. Thus, the 
spring 91A is not pushed from the bottom 44A of the support 44. Nor is the 
spring 91B pushed from the back 44B of the support 44. Even if the support 
member 58c abuts on the back 44B at the unloading position, the leaf 
spring 91B does not actuate the micro-switch 90. Similarly, at the loading 
position, the projection 300 of the leaf spring 91A does not enter the 
optical path p of the optical sensor. It is thus detected that no cassette 
C is mounted on the cassette support 44. 
When a cassette C is placed on the support 44 as shown in FIG. 9B, both 
pins 92A and 92B project outwards, pushing the springs 91A and 91B from 
the bottom 44A and back 44B of the support 44, respectively. In this case, 
the support member 58c abuts on the back 44B of the support 44 at the 
unloading position, whereby the micro-switch 90 is actuated, and the 
projection 300 of the leaf spring 91A enters the optical path p of the 
optical sensor at the loading position. It is thus detected that a 
cassette C is mounted on the cassette support 44. 
FIGS. 10 and 11 show a state in which the cassette chamber 8 shown in FIG. 
1 is provided with a support member 58d according to a fourth 
modification. As shown in these drawings, the support member 58d is 
composed of an air cylinder having a rod 95 that moves up and down. The 
member 58d is situated close to the cassette loading aperture 20 and 
outside the chamber vessel 18. When the cassette support 44 is rotated to 
the outside of the chamber 8 by the rotation mechanism 54, the extended 
rod 95 of the support member 58 pushes up one side portion of the back 
support portion 44B and supports the portion 44B horizontally. The air 
cylinder may be replaced with a lift mechanism that combines a ball screw 
and a drive motor, for example. In short, the support member may be any 
mechanism that can push up the one side portion of the back support 
portion 44B and horizontally support it through up-and-down motion. In the 
case where the support member 58d is thus composed of the drive mechanism, 
it should preferably be located outside the chamber vessel 18 in order to 
restrain production of particles. 
FIGS. 12 to 14 show a cassette chamber according to a second embodiment of 
the present invention. Like reference numerals refer to common components 
that are also used in the first embodiment, and a description of those 
components is omitted. 
In the cassette chamber of the present embodiment, two arms 50A and 50B 
have the same length, and an auxiliary pedestal 42 is mounted on a main 
shaft 40 in parallel relation. A back support portion 44B of a cassette 
support 44 is attached to one side portion of the pedestal 42 by means of 
a hinge 68. The hinge 68 is provided with an elastic member, such as a 
spring, which continually urges the back support portion 44B to be 
separated from the pedestal 42. A bottom support portion 44A of the 
cassette support 44 is provided with a guide groove 70 having the shape of 
a circular arc around the hinge 68. The auxiliary pedestal 42 is provided 
with a stopper plate 42A, which is bonded to the pedestal 42 at right 
angles and extends in the horizontal direction. Formed on the upper 
surface of the stopper plate 42A is a projection 72, which is fitted in 
the guide groove 70. The back support portion 44B, which is separated from 
the auxiliary pedestal 42 by means of the urging force of the elastic 
member attached to the hinge 68, is restrained from being further 
separated from the pedestal as the projection 72 abuts against an end 
portion of the guide groove 70. Thereupon, a separation angle .theta. 
between the back support portion 44B and the auxiliary pedestal 42 is kept 
at 22.5.degree., for example. Thus, the back support portion 44B is 
oriented in an access direction A of a transportation arm 12. 
A guide rod 74 is provided on one side portion or hinge-side portion of the 
bottom support portion 44A of the cassette support 44, and extends on the 
side of the main shaft 40. A rotatable guide roller 76 is mounted on the 
distal end of the rod 74. The roller 76 is formed of a resin in order to 
restrain production of particles. A chamber vessel (not shown) is provided 
with a guide rail member 78 having a groove in which the guide roller 76 
is movably fitted, as shown in FIG. 13. In this case, an upper end portion 
78A of the groove of the rail member 78 is opened so that the guide roller 
76 can be disengaged upward through it. 
The groove of the guide rail member 78 is vertically bent so as to be in 
the form of a somewhat helical circular arc. The groove regulates the 
movement of the guide roller 76 so that the back support portion 44B of 
the cassette support 44 engages the auxiliary pedestal 42 as the pedestal 
42 rotates through 90.degree. around the shaft 40. Thus, when the guide 
rod 74 takes a horizontal position such that the roller 76 is situated at 
the upper end portion 78A of the groove of the guide rail member 78, the 
member 78 causes the auxiliary pedestal 42 and the back support portion 
44B to separate at the angle .theta. from each other, thereby orienting a 
wafer loading/unloading aperture 14 of a cassette C in the moving 
direction A of the transportation arm 12 (see FIG. 12). When the guide 
roller 76 is situated at a lower end portion 78B of the groove of the 
guide rail member 78, on the other hand, the member 78 causes the 
auxiliary pedestal 42 and the back support portion 44B to engage each 
other and directs the aperture 14 of the cassette C upward (see FIG. 14). 
With this arrangement, according to the present embodiment, the necessity 
of the support member 58 according to the first embodiment can be 
obviated. 
The following is a description of the operation of the cassette chamber 
according to the present embodiment. 
When the lift rod 34 (see FIG. 1) is lowered to a predetermined height from 
the state in which the projection 72 abuts against the end portion of the 
guide groove 70 so that the auxiliary pedestal 42 and the back support 
portion 44B are separated at the predetermined angle .theta. from each 
other (or in which the wafer loading/unloading aperture 14 of the cassette 
C is oriented in the access direction A of the transportation arm 12), 
pinion gears 48 and stationary racks 56 mesh with one another, as shown in 
FIG. 12. At this time, the guide roller 76 on the distal end of the guide 
rod 74 engages the upper end portion 78A of the guide rail member 78. When 
the lift rod 34 in this state is further moved downward to lower the lift 
pedestal 32 (see FIG. 1), the main shaft 40 rotates, and the auxiliary 
pedestal 42 and the cassette support 44 rotate so as to project outside 
the chamber vessel. During this rotating operation, the guide roller 76 is 
guided along the groove of the rail member 78. Thus, the back support 
portion 44B of the cassette support 44 engages the auxiliary pedestal 42, 
whereupon the cassette C is carried out of the chamber vessel in a 
horizontal state such that its wafer loading/unloading aperture 14 faces 
upward (see FIG. 14). 
According to the cassette chamber of the present invention, as described 
above, the same effects of the first embodiment can be obtained, and the 
guide rod 74 for setting the cassette C in the horizontal position has the 
guide roller 76, so that the coefficient of friction between the roller 76 
and the guide rail member 78 can be lowered to restrain production of 
particles. 
FIGS. 15 to 22 show cassette chambers according to a third embodiment of 
the present invention. 
As shown in FIG. 15, cassette chambers 118 and 120 according to the present 
embodiment, like the cassette chambers 8 and 10 of the cluster tool 
apparatus shown in FIGS. 23 and 24, are connected to a transfer chamber 6. 
A chamber vessel that forms each of the cassette chambers 118 and 120 has 
a cassette loading aperture 122 and a wafer unloading aperture 124. In 
this case, the apertures 122 and 124 are parallel to each other. More 
specifically, the cassette loading aperture 122 is directed at the 
predetermined angle .theta. (e.g., 22.5.degree.) to the X-axis direction 
and parallel to the access direction A of the transportation arm 12 in the 
transfer chamber 6. 
Since the cassette chambers 118 and 120 have substantially the same 
construction, only the chamber 118 will be described below. 
As shown in FIG. 16, the cassette chamber 118 includes a generally 
rectangular chamber vessel 121 of, e.g., aluminum. The vessel 121 is 
provided with the cassette loading aperture 122 in one side face thereof, 
through which a cassette C can be passed. The aperture 122 is closed by an 
open-close gate door G1. The wafer unloading aperture 124 is formed in the 
upper part of the other side face of the vessel 121. The aperture 124 is 
connected to the transfer chamber 6 by means of an open-close gate valve 
G. 
The cassette C, which is stored with semiconductor wafers W as objects of 
treatment, is constructed in the same manner as the ones according to the 
first and second embodiments, as shown in FIG. 7. The cassette C is set in 
a working region on the side of the cassette loading aperture 122 so as to 
face in the X-axis direction, having its wafer loading/unloading aperture 
14 directed upward. 
A lift pedestal 134 is provided in the chamber vessel 121. A lift rod 135 
is connected to the underside of the pedestal 134. The rod 135 airtightly 
penetrates a bottom portion 121A of the vessel 121 with the aid of a seal 
136, such as an O-ring, and is moved up and down by means of a lift 
mechanism 138. 
As is clearly shown in FIG. 17, a horizontally extending auxiliary pedestal 
142 is rotatably mounted on one side portion of the lift pedestal 134 by 
means of a main shaft 140. As is also shown in FIG. 18, an L-shaped 
cassette support 144 is rotatably attached to one side portion of the 
pedestal 142 by means of hinges 156. More specifically, the main shaft 140 
is first rotatably supported on the one side portion of the lift pedestal 
134 by means of two bearings 146. Pinion gears 148, which constitute part 
of a rotation mechanism 158 (mentioned later), are fixed individually to 
the opposite ends of the shaft 140. Preferably, the gears 148 are formed 
of a resin having relatively high hardness, in order to restrain 
production of particles. The auxiliary pedestal 142 is fixed to the main 
shaft 140 by means of screws 150. Thus, the pedestal 142 can rotate 
integrally with the shaft 140. 
On the other hand, the L-shaped cassette support 144 is composed of a 
bottom support portion 152 for bearing and holding the bottom face 30 of 
the cassette C and a back support portion 154 for bearing and holding the 
back face 24 of the cassette. These two support portions 152 and 154 are 
bonded together at right angles to each other. The bottom support portion 
152 is formed of two support plates 152A and 152B, which are coupled 
together by means of, for example, three height adjusting screws 157 (only 
two of which are shown in FIG. 16). The distance between the plates 152A 
and 152B can be changed to adjust the height of the cassette support 144 
by turning the screws 157. In this case, the support plate 152B is 
attached to the one side portion of the auxiliary pedestal 142 by means of 
the hinges 156. 
As is clearly shown in FIG. 18, two stationary racks 160 are set up 
vertically on the bottom portion 121A of the chamber vessel 121, in 
positions where they can mesh with their corresponding pinion gears 148. 
Preferably, the racks 160 are formed of a resin having relatively high 
hardness, in order to restrain production of particles. 
The stationary racks 160, along with the pinion gears 148, constitute the 
rotation mechanism 158 for rotating the cassette support 144. The racks 
160 mesh with their corresponding gears 148 that ascend and descend as the 
lift rod 135 moves up and down. As the gears 148 are rotated, the main 
shaft 140 is rotated, and the cassette support 144, which is fixed to the 
shaft 140 by means of the auxiliary pedestal 142, is rotated. More 
specifically, the racks 160 have their tooth shape and height set so that 
they can rotate the pinion gears 148 through 90.degree., and moreover, can 
rotate the descending and ascending gears 148 in the counterclockwise and 
clockwise directions of FIG. 1, respectively. Thus, when the lift pedestal 
134 descends, the rotation mechanism 158 rotates the cassette support 144 
through 90.degree. in the counterclockwise direction, thereby causing it 
to project outward from the cassette chamber 118 through the cassette 
loading aperture 122. When the pedestal 134 ascends, the mechanism 158 
rotates the support 144 through 90.degree. in the clockwise direction, 
thereby situating it inside the chamber 118. 
In order to position the cassette support 144 with respect to the lift 
pedestal 134, the pedestal 134 is provided with a projection 169 on its 
upper surface, while the auxiliary pedestal 142 has a recess 170 on its 
lower surface (see FIG. 16). The projection 169 can be fitted in the 
recess 170. 
Outside the chamber vessel 121, on the other hand, an actuator 162 formed 
of, e.g., an air cylinder is located close to the cassette loading 
aperture 122, as shown in FIG. 15 and FIGS. 18 to 21. The body of the 
actuator 162 is fixed to the outer surface of the chamber vessel 121 by 
means of a support arm 164. Also, the actuator 162 has an engaging rod 166 
capable of extension and contraction. As shown in the drawings, the rod 
166 has a hook 166A at its distal end, which is bent upward at an angle of 
90.degree.. The hook 166A can be fitted in an engaging hole 168 (see FIG. 
18) of the back support portion 154 that is rotated through 90.degree. to 
the outside of the chamber 118. When the actuator 162 is actuated with the 
hook 166A fitted in the hole 168, the whole cassette support 144 is 
rotated through the predetermined angle .theta. around the hinges 156. 
The following is a description of the operation of the cassette chamber 118 
constructed in this manner. 
FIGS. 15, 16 and 18 show a state in which the cassette C, holding the 
semiconductor wafers W therein, is located in a wafer delivery position in 
the upper part of the chamber vessel 121. In this state, the cassette 
support 144 is oriented in the access direction (moving direction) A of 
the transportation arm 12 (or is directed at the predetermined angle 
.theta. to the X-axis direction). Thus, the wafer loading/unloading 
aperture 14 of the cassette C placed on the cassette support 144 is 
opposed to the wafer unloading aperture 124 of the chamber vessel 121, and 
is also oriented in the access direction A of the arm 12 in the transfer 
chamber 6. In this state, moreover, the load of the cassette C is borne by 
the support plate 152A of the bottom support portion 152 of the cassette 
support 144. 
In discharging the cassette C in this state from the chamber vessel 121, 
the lift rod 135 is first moved downward to lower the lift pedestal 134. 
When the pedestal 134 is lowered to a predetermined height, the pinion 
gears 148, fixed individually to the opposite ends of the main shaft 140, 
mesh with the teeth of the stationary racks 160 that are set up on the 
bottom portion 121A of the vessel 121. When the lift pedestal 134 is 
further lowered with the gears 148 and the racks 160 in mesh with one 
another, the gears 148 rotate in the counterclockwise direction of FIG. 16 
as they descend along their corresponding racks 160. Also, the main shaft 
40, which is integral with the pinion gears 148, descends rotating 
counterclockwise. Accordingly, the auxiliary pedestal 142, which is fixed 
to the shaft 40, and the cassette support 144 also descend rotating 
counterclockwise, whereupon the wafer loading/unloading aperture 14 of the 
cassette C, having so far been oriented in the horizontal direction, 
starts gradually to turn upward (see FIG. 19). 
When the cassette support 144 is rotated counterclockwise through 
90.degree. in this manner, the descent of the lift pedestal 134 is 
stopped, and the support 144 is stopped from rotating further. FIG. 20 
shows the resulting state. As shown in FIG. 20, the back support portion 
154 projects outward from the chamber vessel 121 through the cassette 
loading aperture 122 in a manner such that it is kept horizontal. Thus, 
the cassette C also projects outside the vessel 121, and its load is borne 
by the back support portion 154 with the wafer loading/unloading aperture 
14 facing upward (in the Z-axis direction). In this state, moreover, the 
hook 166A of the engaging rod 166 of the actuator 162, previously held on 
standby in a predetermined position, is fitted into the engaging hole 168 
in the back support portion 154 of the cassette support 144. When the rod 
166 in this state is extended to cause the support 144 to rotate through 
the angle .theta. around the hinges 156 and separate from the auxiliary 
pedestal 142, as shown in FIG. 21, the cassette C is oriented in the 
X-axis direction. The state of the cassette C at this point of time is 
indicated by full line in FIG. 22 
When the aforesaid operation is carried out reversely from the state shown 
in FIG. 21, the cassette C is loaded into the chamber vessel 121, and the 
wafer loading/unloading aperture 14 is oriented in the access direction A 
of the transportation arm 12. Thus, when anthe cassette C is placed 
horizontal on the back support m ember 154 of the cassette support 144 in 
the state shown in FIG. 21 with the aperture 14 upward, the engaging rod 
166 of the actuator 162 is contracted, whereupon the support 144 is 
rotated through the angle .theta.. Thus, the bottom support portion 152 of 
the support 144 is caused to engage the auxiliary pedestal 142. When the 
lift pedestal 134 in this state is raised, the pinion gears 148 ascend 
along their corresponding stationary racks 160, and the main shaft 140 
rotates clockwise. As a result, the cassette support 144 also rotates 
clockwise to be taken into the chamber vessel 121. When the pedestal 134 
is further raised so that the cassette support 144 is rotated clockwise 
through 90.degree., the support 144 is held in the same posture as the one 
shown in FIG. 18. 
According to the cassette chamber of the present embodiment, as described 
above, substantially same effects of the first and second embodiments can 
be obtained. Unlike the ones according to the first and second 
embodiments, the cassette chamber according to the present embodiment 
requires use of the actuator 162 for rotating the cassette C in the 
horizontal direction. Since the actuator 162 is located outside the 
cassette vessel 121, however, there is no possibility of produced 
particles adhering to the wafer surface. Also in the case of the present 
embodiment, the lift pedestal 134 may have a space that can store a 
plurality of dummy wafers for inspection, for example. 
Semiconductor wafers have been described as typical objects of treatment 
according to the aforementioned embodiments. Alternatively, however, glass 
substrates, LCD substrates, etc. may be used as objects of treatment. 
Moreover, the apparatus to which the cassette chamber according to the 
present invention is applied is not limited to the so-called cluster tool 
apparatus. 
Additional advantages and modifications will readily occur to those skilled 
in the art. Therefore, the invention in its broader aspects is not limited 
to the specific details and representative embodiments shown and described 
herein. Accordingly, various modifications may be made without departing 
from the spirit or scope of the general inventive concept as defined by 
the appended claims and their equivalents.