Substrate transferring apparatus

According to the invention, there is provided a substrate transferring apparatus for transferring substrates from a substrate transport container containing a plurality of substrates to be treated to a substrate holder for holding a plurality of substrates to be treated or vice versa, the apparatus including arms for supporting substrate, a supporting member for supporting the arms, and a drive arrangement for driving the supporting member to operate. Each of the arms include a plate shaped arm main body having a connecting section for connecting the arm to the drive arrangement, supporting sections having a thickness greater than that of the arm main body for supporting corresponding peripheral areas of the substrate, and stoppers having a thickness greater than that of the supporting sections for abutting lateral sides of the substrate to rigidly hold the substrate.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to an apparatus for transferring semiconductor 
substrates. 
2. Description of the Related Art 
Semiconductor substrates are normally housed in a substrate container such 
as wafer cassettes or wafer carriers when conveyed from a work station to 
another in a manufacturing line. Such containers are normally made of 
plastic material or a similar lightweight and low cost material. 
On the other hand, plastic containers of the above described type cannot, 
however, be used when substrates are heat treated on a batch basis and, 
therefore, if such is the case, they are replaced by a substrate holder 
such as wafer boats as they are usually called, made of a material which 
is resistive to heat and corrosion, chemically stable and less liable to 
produce dusts such as quartz. 
Normally, a particular apparatus is installed to automatically transfer 
semiconductor substrates from a substrate container to a substrate holder. 
Such a transferring apparatus typically comprises a number of arms for 
respectively supporting substrates, a drive means for driving the arms to 
operate and a rotating means for changing the direction to which the 
transferring apparatus is oriented. The arms of a transferring apparatus 
under consideration may be of the type that hold substrates by vacuum as 
disclosed in Published Unexamined Japanese Patent Application (JP-A) No. 
2-71544 or the type that dispose substrates on respective supporting 
tables as disclosed in Published Examined Japanese Patent Application 
(JP-B) No. 2-39009 and JP-A-64-6047. 
While the arm of the vacuum type is capable of securely holding a 
substrate, it can also gather and suck dusts from the surroundings, which 
by turn adhere to the substrate to consequently reduce the yield of 
manufacturing semiconductor devices. 
With the arm of the supporting table type as disclosed in JP-B-2-39009, on 
the other hand, in a case that the substrate is charged, the entire 
surface of the substrate sustained on the table is held in contact with 
the surface of the wafer supporting table to generate static electricity 
between them that causes the substrate and the table to attract or repel 
each other. Consequently, the substrate is held on the supporting table 
under a rather unstable condition and can eventually drop from the table 
or generate dusts as they are scratched against each other. The generated 
dusts can by turn adhere to the substrate to consequently reduce the yield 
of manufacturing semiconductor devices as in the case of the vacuum type. 
SUMMARY OF THE INVENTION 
It is, therefore, an object of the present invention to provide a substrate 
transferring apparatus that reduces generation of static electricity while 
securely holding substrates and, at the same time, effectively prevents 
dusts from adhering to the substrates so that the operation of 
transferring substrates can be carried out in a reliable manner. 
According to the invention, the above object is achieved by providing a 
substrate transferring apparatus for transferring substrates from a 
substrate transport container containing a plurality of substrates to be 
treated to a substrate holder for holding a plurality of substrates to be 
treated or vice versa, the apparatus comprising: 
arms for supporting substrates; 
a supporting member for supporting the arms; and 
a drive means for driving the supporting member to operate; 
wherein each of the arms including: 
a plate-shaped arm main body having a connecting section for connecting the 
arm to the drive means; 
supporting sections having a thickness greater than that of the arm main 
body for supporting peripheral areas of the substrate; and 
stoppers having a thickness greater than that of the supporting sections 
for abutting lateral sides of the substrate to rigidly hold the object. 
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 PREFERRED EMBODIMENTS 
Now the present invention will be described in greater detail by referring 
to the accompanying drawings that illustrate a preferred embodiment of the 
invention. 
FIG. 1 illustrates a schematic sectional view of a vertical-type heat 
treatment apparatus 1 incorporating an embodiment of substrate 
transferring apparatus according to the invention. Said heat treatment 
apparatus 1 is disposed in a maintenance room M and in contact with a 
clean room R. A lateral wall of the vertical-type heat treatment apparatus 
is connected to a separating wall P installed between the maintenance room 
M and the clean room R. Thus, the maintenance room M is partitioned by the 
separting wall P and the vertical-type heat treatment apparatus. 
The vertical-type heat treatment apparatus 1 is divided into an upper 
chamber 12 and a lower chamber 13 by a partition 11. A vertical-type 
heating furnace 20 is vertically arranged in the upper chamber 12. A 
reaction vessel 30 having a double wall structure is housed in the heating 
furnace 20. Below the reaction vessel 30 and in the lower chamber 13 is 
disposed a lift mechanism 40 for raising and lowering a substrate holder 
(hereinafter referred to as wafer boat) 50 holding a number of substrates 
61 horizontally with a given distance between any two adjacent ones in 
order to load them into or unload them from the reaction vessel 30. A 
substrate transferring apparatus 70 is disposed between the lift mechanism 
40 and a substrate container (hereinafter referred to as wafer cassette) 
60 for transferring the untreated substrates 61 from the wafer cassette 60 
that contains them to the wafer boat 50 for heat treatment and then 
returning the substrates 61 from the wafer boat 50 to the wafer cassette 
60 after heat treatment. 
The upper chamber 12 is in communication with the clean room R through an 
opening 12A cut through the wall separating the clean room R and the 
maintenance room M and also with the lower chamber 13 through a fan 80 and 
a filter 90 disposed at an opening cut through the partition 11 that 
constitutes the floor of the upper chamber 12. The fan 80 draws clean air 
in the clean room R through the opening 12A and feeds it into the lower 
chamber 13 and the filter 90 removes dusts from the air being fed into the 
lower chamber 13 so that the wafer cassette 60 may be subjected to clean 
blowing air to prevent dusts from adhering to the substrates 61 on the 
wafer cassette 60. The filter 90 may typically be a HEPA filter or a ULPA 
filter. 
A swing door 15 is fitted to the wall of the lower chamber 13 disposed 
opposite to the clean room R by means of hinges 14 and a first room 16 is 
formed inside the door 15 when the door 15 is closed. A fan 100, filter 
110 (similar to the filter 90) and a reflector plate 120 are disposed 
inside the door 15 and at an opening 13A cut through the wall of the lower 
chamber 13 to which the door 15 is fitted. The first room 16 and the lower 
chamber 13 are held in communications with each other. 
A second room 17 is arranged under the lower chamber 13. The clean 
room-side and the door-side walls partitioning the second room 17 and the 
clean room R are provided with an opening 13B and an opening 13C, 
respectively. Thus, the clean room R and the first room 16 are held in 
communication with each other so that air in the clean room R is blown 
into the lower chamber 13 by the fan 100. In other words, the second room 
17 operates as an air duct connecting the clean room R and the lower 
chamber 13. The opening 13C is also provided with a filter (not shown). 
Therefore, a horizontal air flow is produced by the fan 100 to move clean 
air in the clean room R into the lower chamber 13 and blow it onto the 
substrates 61 held by the wafer boat 50 to prevent dusts from adhering to 
them. Since the heat emitted from the unloaded the wafer boat 50 after 
heat treatment is reflected into the lower chamber 13 by the reflector 
plate 120, the filter 110 is protected against any damaging heat. 
The lower chamber 13 is also provided with a means for neutralizing any 
electric charges generated there such as an ionizer. 
The heating furnace 20 disposed in the upper chamber 12 is a hollow 
cylinder which is closed at the top and open at the bottom. More 
specifically, the heating furnace 20 comprises a shell 23 made of 
stainless steel or a similar material and lined with a heat insulating 
member 22 and a helical heater 21 arranged on the inner surface of the 
heat insulating member 22. The heating furnace 20 can evenly and stably 
heat the inside of the reaction vessel 30 under a controlled manner by 
means of the heater 21 to temperature required for the heat treatment of 
substrates 61 typically between 500.degree. and 1,200.degree. C. 
The reaction vessel 30 disposed in the heating furnace 20 is coaxially 
aligned with the heating furnace 20. The reaction vessel 30 is a double 
wall structure comprising an outer tube 31 which is made of a material 
resistive to heat and corrosion and closed at the top whereas it is open 
at the bottom and an inner tube 32 which is made of the material of the 
outer tube 31 and coaxially arranged within the outer tube 31 with a space 
provided therebetween. 
The reaction vessel 30 is also provided with a manifold 33 pressed against 
the lower end of the outer tube 31 by a holding mechanism (not shown) with 
an O-ring (not shown) made of a heat-resistive and resilient material. The 
manifold 33 supports the inner tube 32 by means of an inwardly projecting 
extension 33A and can hermetically seal the reaction vessel 30 as a flange 
33B disposed at its lower end is held in close contact with a 
corresponding flange of the wafer boat 50. The manifold 33 is by turn 
provided with a gas discharge pipe 33C made of a material same as that of 
the manifold 33 itself and connected to a gas discharge system comprising 
a vacuum pump for discharging a gas inside the reaction vessel 30 and 
first and second gas feed pipes 33D, 33E which are made of a material 
resistive to heat and corrosion such as quartz and disposed below the gas 
discharge pipe 33C, running through the manifold main body 33, the first 
and second gas feed pipes 33D, 33E being bent to have respective inner 
ends turned upward. The gas feed pipes 33D, 33E are connected to a gas 
supply source (not shown) for feeding gas necessary for the heat treatment 
of the substrates 61, involving gas diffusion. 
The lift mechanism 40 has a configuration as illustrated in FIG. 2. It 
comprises a drive section 41, to which a ball screw 42 is engaged. A pair 
of upright linear guides 43 are extending upward from the drive section 
41. A supporting table 44 is engaged with the ball screw 42 so that it 
moves up and down as the ball screw 42 is driven to rotate by the drive 
section 41. The rising and falling movements of the supporting table 44 
for a heat treatment operation is so programmed that the wafer boat 50 
which is carrying substrates is automatically loaded into the reaction 
vessel 30 for heat treatment and then taken out of the reaction vessel 30 
after the completion of the heat treatment. 
The wafer boat 50 is made of a material such as quartz which is highly 
resistive to heat and corrosion and comprises four poles 51 each provided 
with a large number of horizontal grooves 51A typically between 100 and 
150, a pair of discs 52 for securely and rigidly holding the upper and 
lower ends of the four poles 51, an insulating cylinder 53 disposed below 
the lower disc 52 and a flange 54 fitted to the lower end of the 
insulating cylinder 53. 
The wafer boat 50 is so designed that it hermetically seals the reaction 
vessel 30 as the flange 54 abuts the flange 33B of the manifold 33 when 
the wafer boat 50 is loaded into the reaction vessel 30. The horizontal 
grooves 51A of each of the poles 51 are mutually spaced apart and arranged 
at a constant pitch. The distance between two adjacent ones of the grooves 
51A is set such that an arm of the substrate transferring apparatus can be 
moved into the space between the two substrates held in two adjacent 
grooves without touching the substrates as will be described in greater 
detail hereinafter. 
The substrate transferring apparatus 70 is disposed near the lift mechanism 
40 and typically has a configuration as illustrated in FIG. 2. It 
comprises a drive section 71, to which a ball screw 72 is engaged. A pair 
of upright linear guides 73 are extending upward from the drive section 
71. A supporting table 74 is engaged with the ball screw 72 so that it 
moves up and down as the ball screw 72 is driven to rotate by the drive 
section 71. A rotating drive mechanism 75 is fitted to a front area of the 
supporting table 74. A rectangular main body 76 is fitted to the drive 
shaft 75A (see FIG. 4) of the rotating drive mechanism 75 such that it is 
driven by the driving force of the drive mechanism 75 to rotate by an 
angle of .theta..sub.1. The main body 76 is provided with a plurality of 
arms 77 (or six in the illustrated embodiment). The movements of the arms 
77 for a heat treatment operation is so programmed that they transfer 
respective substrates 61 from the wafer boat 50 to the wafer cassette 60 
and vice versa. 
The main body 76 has a configuration as illustrated in FIGS. 3 and 4. It 
comprises cabinet 76A, on which a pair of motors 76B (only one is shown) 
that operate independently are disposed. Each of the motors 76B is 
provided with two pairs of pulleys 76C respectively disposed at the front 
and rear ends thereof. Each of the two pairs of pulleys 76C are connected 
by a drive belt 76D, which is driven to run by the related motor 76B. 
First and second supporting members 76F and 76G are connected to the 
respective drive belts 76D. Two slits 76E are formed through the top wall 
of the cabinet and the first and second supporting members 76F and 76G 
runs through the respective slits 76E. A total of five arms 77 are 
commonly secured to an end section of the first supporting member 76F, 
whereas a single arm 77 is secured to a corresponding end section of the 
second supporting member 76G. The arms 77 secured to the first supporting 
member 76F and the arm 77 secured to the second supporting member 76G move 
back and forth in the directions as indicated by arrows L in FIG. 3 as the 
drive belts 76D are driven to run by the respective drive motors 76B. 
Thus, movement of the first supporting member 76F is utilized where it is 
desired to move five arms simultaneously, while supporting member 76G is 
utilized for independently moving a single arm. 
As illustrated in FIG. 4, five arms 77 are interposed by a pair of plates 
at an end section of the first supporting member 76F with a spacer 76H 
disposed between any two adjacent arms 77 to separate them, the arms 77 
and the spacers 76H being rigidly secured by means of a plurality of pins 
76I. Similarly, a single arm 77 is interposed by a pair of plates at an 
end section of the second supporting member 76G. 
The arms 77 are made of a ceramic that are resistive to heat and corrosion 
material such as silicon carbide, alumina, sapphire and the like or a 
material that do not damage substrates with which the arms may contact 
when substrates are put thereon. Alternatively, the arm main bodies may be 
made of alumina coated with silicon carbide by using a CVD technique or 
ion-plated with diamond. The efficient thickness of the coating layer of 
silicon carbide or diamond is between 50 and 100 .mu.m. If the thickness 
is less than 50 .mu.m, the coating layer can be affected by the unevenness 
of the surface of the arm main body, whereas, if the thickness exceeds 100 
.mu.m, the coating layer forming process is to be costly. 
As illustrated in FIG. 5, each of the arms 77 comprises an arm main body 
77A having a connecting section 77D for connecting the arm to a drive 
means, a pair of supporting sections 77B having a thickness greater than 
that of the arm main body for supporting corresponding peripheral areas of 
the substrate and a stopper 77C having a thickness greater than that of 
the supporting sections for abutting a lateral side of the substrate to 
rigidly hold the substrate. 
If a 6-inch wafer is held by the arm, the arm main body 77A will have a 
thickness of approximately 0.8 mm (and the connecting section will have a 
thickness of 1.5 mm). If, on the other hand, an 8-inch wafer is handled by 
the arm, the thickness of the arm main body 77A will be approximately 1.1 
mm (and that of the connecting section will be 2.1 mm). The arm main body 
77A will be approximately 60 mm wide when it is used for a 6-inch wafer, 
whereas it will be approximately 70 mm wide when it is used for an 8-inch 
wafer. 
The supporting sections 77B will have a thickness of approximately 0.3 mm 
if the arm is used for a 6-inch wafer, whereas its thickness will be 
approximately 0.5 mm if the arm handles an 8-inch wafer. These values are 
selected by considering the fact that a wafer normally show a maximum warp 
of approximately 150 .mu.m when heat treated. 
The stopper 77C may well have a thickness approximately 60% of that of the 
substrate to be handled by the arm. Therefore, if the substrate is a 
6-inch wafer, the stopper 77C will have a thickness of approximately 0.4 
mm or more (i.e., at least 60% of the wafer thickness), considering that 
the wafer is approximately 0.65 mm thick. If, on the other hand, the 
substrate is an 8-inch wafer, the stopper 77C will have a thickness of 
approximately 0.45 mm or more in view of the fact that the wafer is 
approximately 0.75 mm thick. The surface of the stopper 77C is preferably 
tapered toward the supporting section 77B disposed closer to it so that a 
substrate may easily and smoothly be moved onto and away from the arm. 
The connecting section 77D of the arm main body 77A will have a thickness 
approximately between 1.3 to 1.5 mm if the substrate to be handled by the 
arm is a 6-inch wafer, whereas it will have a thickness approximately 
between 1.9 and 2.1 mm if the substrate is an 8-inch wafer. The holes in 
the connecting section 77D are used to receive pins 77E for securing the 
arm to the end section of the supporting member. 
The arm can securely hold a substrate by means of the supporting sections 
77B and the stopper 77C. If the substrate is warped by heat during heat 
treatment, the substrate will not come to contact the surface of the arm 
main body 77A because the supporting sections 77B are considerably thicker 
than the arm main body 77A. Additionally, the substrate carried by the arm 
is protected against any possible displacement and eventual falling that 
can take place when the arm is moving to transfer the substrate because of 
the provision of a pair of supporting sections 77B and a stopper 77C. 
Finally, any possible attractive force (in the case where the arm is made 
of silicon carbide) or repellent force (in the case where the arm is made 
of alumina) due to the static electricity generated between the arm 77 and 
the substrate will be significantly reduced because the supporting 
sections 77B of the arm touch only small peripheral areas of the 
substrate. 
The attractive or repellent force due to the static electricity generated 
between the arm 77 and the substrate can be further reduced if a 
longitudinally oblong hole 77F is formed approximately at the center of 
the arm main body 77A as illustrated in FIG. 6 in order to reduce the 
surface area of the arm main body 77A that can be electrically charged. 
The provision of such a hole 77F can also suppress adhesion of dusts to 
the arm 77 because it allows a large downward flow of air. The static 
electric charge on the arm can be reduced by an electric charge 
neutralizing means as illustrated in FIG. 1. FIG. 7 shows an alternative 
arm having a pair of holes 77F separated by a dividing section 77G. With 
such an arrangement, the mechanical strength of the arm main body 77A may 
be improved as compared with that of FIG. 6, while the arm may also allow 
a large downward flow of air. 
FIG. 8 shows another alternative arm, in which the stopper 77C and the 
supporting sections 77B of the arm of FIG. 5 are replaced by a set of 
blocks 77H rigidly fitted to the arm main body 77A at the four corners by 
adhesion or glass welding. Since the areas where the supporting sections 
77B contact with the substrate are significantly reduced with such an 
arrangement if compared with the arms of FIGS. 5 through 7, adhesion of 
dusts to the substrate is further suppressed to improve the yield of 
manufacturing substrates using such arms. 
FIGS. 9 and 10 illustrate still other alternative arms that respectively 
resemble the arms of FIGS. 6 and 7 having one or more holes 77F but in 
each of which the stopper is replaced by a set of blocks 77H rigidly 
fitted to the arm main body 77A to reduce the area of contact between the 
supporting sections 77B and the substrate while maintaining a large 
downward flow of air. The arm of FIG. 10 having a pair of holes 77F 
separated by a dividing section 77G will show a particularly enhanced 
mechanical strength of the arm main body 77A. 
While each of the arms of FIG. 9 and 10 is provided with four blocks 77H, 
each comprising a supporting section 77B and a stopper 77C, the number of 
blocks to be used for a single arm is not limited to four and may be 
varied so long as a substrate is securely held in position by the blocks. 
FIG. 11 illustrates an alternative arm provided with three blocks 77H 
arranged on an arm main body 77A. 
The form of the arm main body 77A needs to be determined by considering the 
arrangement of poles 51 of wafer boat 50. FIG. 12 shows a typical 
arrangement of poles 51B through 51E of wafer boat 50. The arm 77 is 
inserted between a pole 51B and another pole 51E for loading a substrate 
on a wafer boat 50. Therefore, the width of the arm main body 77A needs to 
be smaller than the distance separating the poles 51B and 51E. Thus, the 
arm main body 77A is normally realized in an oblong and substantially 
rectangular form as illustrated in any of FIGS. 5 through 11. 
The form of the arm main body 77A is, however, not limited to that of any 
of FIGS. 5 through 11 and may be so realized as to show a tapered front 
end section opposite to the connecting section as illustrated in FIG. 12 
to reduce the possibility with which the front end of the arm main body 
77A collides with the pole 51B or 51E. Alternatively, the arm main body 
77A itself may be tapered toward the front end as illustrated in FIG. 13. 
In any case, the arm main body 77A has a rather large proper width to 
stably support a substrate on it. FIG. 14 illustrates a still another 
alternative arm, where blocks 77H, each comprising a supporting section 
77B and a stopper 77C, are adhered to the surface of the arm main body 
77A. 
If poles 51F through 51H are arranged on a wafer boat 50 in a manner as 
illustrated in FIG. 15, the arm main body 77A may alternatively be 
provided with a semicircular cut out area at the center of the front end 
for receiving a pole 51G without touching it. FIG. 16 illustrates a still 
another alternative arm main body 77A provided with a semicircular cut-out 
area and additionally with four blocks 77H adhered on the arm main body 
77A, each of the blocks comprising a supporting section 77B and a stopper 
77C. FIG. 17 shows a still another alternative arm main body 77A which 
resembles to that of FIG. 16 but provided with only three blocks 77H. 
In order to reduce the weight of the arm main body 77A, it may be so 
realized as to show a thickness that gradually decreases toward the front 
end thereof. Alternatively, it may be realized by bonding a flat plate and 
a plate having a recess to form a hollow central area to achieve the same 
objective. Still alternatively, the arm main body 77A may be provided with 
a plurality of recessed steps and a plurality of supporting sections such 
that it may be used for substrates with different sizes. FIG. 18 typically 
shows such an alternative arm main body 77A having two recessed steps 
respectively with two different sets of supporting sections 77I and 77J so 
that they may be used respectively for a 6-inch wafer and an 8-inch wafer. 
The alternative configurations of the arm main body 77A of FIGS. 5 through 
18 may be appropriately combined to produce additional alternative arm 
main bodies. 
The wafer cassette 60 as illustrated in FIG. 2 is of a known conventional 
type made of a material resistive to heat and corrosion. It can normally 
contain as many as 25 substrates such as those to be heat treated and/or 
dummy substrates as well as substrates to be used for monitoring purposes 
and is provided on the inner surface of its rectangular cabinet with a 
plurality of horizontal grooves arranged at a given pitch for holding 
substrates. A number of wafer cassettes 60 having a configuration as 
described above is commonly placed on a supporting table 130 that can be 
rotated by angle .theta..sub.2 in the directions as indicated by arrows in 
FIG. 2 by means of a drive mechanism (not shown). The drive mechanism for 
the supporting table 130 is so controlled by a program that, when the main 
body 76 of the substrate transferring apparatus 70 is raised or lowered to 
make itself ready to take out the substrates in the wafer cassettes 60, 
the wafer cassettes 60 are disposed exactly vis-a-vis the main body 76 of 
the substrate transferring apparatus 70. 
A vertical-type heat treatment apparatus incorporating a substrate 
transferring apparatus 70 according to the invention will operate in a 
manner as described below, following a program stored in the control unit 
of the heat treatment apparatus. 
Firstly, for heat treatment of substrates 61, the cassette supporting table 
130 is rotated by the drive mechanism. Simultaneously, the lift mechanism 
71 is operated to drive the ball screw 72 to rotate so that the supporting 
table 74 is raised or lowered along the linear guides 73, while the drive 
mechanism 75 is operated to drive the main body 76 to rotate until a 
particular wafer cassette 60 is situated exactly vis-a-vis the substrate 
transferring apparatus 70. 
Then, the motor 76B of the main body 76 of the substrate transferring 
apparatus 70 is operated to drive the drive belts 76D to run and move the 
first supporting member 76F connected to the drive belts 76D. Thus, the 
five arms 77 fitted to the first supporting member 76F is moved forward 
from the main body 76 simultaneously and inserted into the respective 
spaces separating the substrates 61 to be taken out of a wafer cassette 
60. The substrates 61 then come to be supported at peripheral areas by the 
respective sets of supporting sections 76B of the arms 77 when the arms 
are slightly raised. As the motor 76 is reversely driven under this 
condition to make the drive belts 76D to run in the reverse direction and 
retract the arms 77 from the wafer cassette 60, the five substrates 61 are 
moved out of the wafer cassette 60. Note that each of the substrate 61 is 
securely held onto the corresponding arm 77 by a set of supporting 
sections 77B and stoppers 77C of the arm 77. Any static electric charge 
that may be generated between each of the arms 77 and the substrate 61 
held on it will be neutralized by an electric charge neutralizing means. 
Then, the lift mechanism 71 and the drive mechanism 75 are operated to 
raise or lower the supporting table 74 along the linear guides 73 and 
simultaneously rotate the main body 76 until the substrate transferring 
apparatus 70 comes vis-a-vis the wafer boat 50 located at the unloading 
position. Then, the motor 76B of the main body 76 of the substrate 
transferring apparatus 70 is operated to drive the drive belts 76D to run 
so that the first supporting member 76F connected to the drive belts 76D 
is moved accordingly. The five arms 77 fitted to the first supporting 
member 76F and now supporting the substrates 61 are simultaneously moved 
forward from the main body 76 and inserted into the wafer boat 50. Under 
this condition, the substrates 61 are received at peripheral areas in the 
respective grooves 51A of the poles 51. When the arms 77 are lowered 
slightly, the substrates 61 on the respective arms 77 come to be totally 
supported by the wafer boat 50. Under this condition, the motor 76B is 
reversely driven to make the drive belts 76D to run in the reverse 
direction and retract the arms 77 from the wafer boat 50. Now, a first 
cycle of operation of transferring substrates is completed. This cycle of 
operation will be repeated for several times until a predetermined number 
of substrates 61 are moved from the wafer cassette 60 to the wafer boat 50 
for heat treatment. 
When the operation of transferring a predetermined number of substrates 61 
into the wafer boat 50 on the unloading position is over, the lift 
mechanism 40 will be subsequently operated for a next sequence of 
operation. More specifically, as the drive section 41 is driven to rotate 
the ball screw 42, the supporting table 44 is raised along the linear 
guides 43 until the wafer boat 50 is loaded into the reaction vessel 30. 
When a predetermined heat treatment operation is completed, the drive 
section 41 is operated again to drive the ball screw 42 to rotate in the 
reverse direction and lower the supporting table 44 along the linear 
guides 43 until the wafer boat 50 is completely moved unloaded from the 
reaction vessel 30. Thereafter, the heat treated wafer substrates 61 are 
taken out of the wafer boat 50 by means of the substrate transferring 
apparatus 70 and loaded into a given wafer cassette 60. 
Since the substrates 61 are supported by the respective arms and the poles 
only at certain peripheral areas during the above described transferring 
operation, they are held under a stable condition and not significantly 
affected by static electricity. Additionally, since each arm 77 is 
provided with a number of stoppers 77C, the substrate 61 on it will not 
drop from it if the arm 77 is horizontally slued. 
While the present invention has been described above in terms of an 
embodiment incorporated into a vacuum type heat treatment apparatus, a 
substrate transferring apparatus according to the invention may 
alternatively be used for an atmospheric pressure type heat treatment 
apparatus or any other apparatus involving the operation of transferring 
substrates. 
As described above in detail, substrates can be can stably be transferred 
from a substrate container to a substrate holder or vice versa by a 
substrate transferring apparatus according to the invention without being 
affected by static electricity and without fear of dropping because they 
are supported by respective supporting sections and stoppers of arms only 
at certain peripheral areas thereof. Thus, a substrate transferring 
apparatus according to the invention can effectively prevent dusts from 
adhering to the substrate and hence improve the yield of manufacturing 
semiconductor substrates. 
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 devices 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.