Device having brush for scrubbing substrate

A substrate cleaning device comprising a motor for rotating a wafer together with a spin plate, claws for holding the wafer so as to form a space between the spin plate and the wafer, a jet nozzle through which cleaning solution is jetted onto an upper surface of the wafer, a rotating brush for brush-cleaning the upper surface of the wafer, a mechanism for blowing nitrogen gas or pure water onto the lower surface of the wafer, and a mechanism for exhausting the space between the spin plate and the wafer, wherein a solution passage for the solution blowing mechanism and an exhaust passage for the exhaust mechanism are formed in a drive shaft of the motor and communicated with the space.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a device for scrubbing substrates such as 
semiconductor wafers, LCD substrates, photo-masks, ceramic substrates, 
compact disks and printed substrates by a brush while applying solution to 
substrates. 
2. Description of the Related Art 
In the case of the substrate scrubbing devices, contaminating particles can 
be removed from the wafer surface in such a way that the brush having 
nylon or mohair fibers planted is pushed against the semiconductor wafer 
while rotating the wafer together with spin chuck and applying cleaning 
solution to the wafer. 
Japanese Patent Disclosure Sho 57-45233 discloses a device wherein vortexes 
are caused in a vortex chamber of the spin chuck and negative pressure 
caused by these vortexes is used to hold the semiconductor wafer. The 
vortex chamber has openings in the surface of the chuck and an inlet 
formed in a side wall thereof communicated with a passage in a rotating 
shaft of the spin chuck. In short, pressurized gas or solution is jetted 
into the vortex chamber through the inlet to cause vortexes in the vortex 
chamber. 
In the case of this type of conventional device, however, dust such as 
particles caused in bearings are blown together with solution to the 
semiconductor wafer. They are thus caused to adhere to the bottom surface 
of the wafer, thereby causing the productivity to be lowered. In addition, 
they are also caused to enter into a motor to break it down. 
Japanese Patent Publication Hei 3-9607 discloses a spin chuck of the grip 
type wherein the wafer is gripped at its outer rim by three or more claws. 
In the case of this type of spin chuck, however, the device becomes 
complicated in structure and large in size because it must have drive 
sources for two system lines. 
Furthermore, a spin chuck wherein weights are connected to chuck sections 
which can move toward the rotating center of the wafer and the chuck 
sections are moved by centrifugal force added to the weights when the 
wafer is rotated. The wafer is held by the chuck sections thus moved. In 
the case of this type of spin chuck, however, the extent to which the 
chuck sections can be moved becomes smaller when the rotation of the wafer 
is started and stopped. This makes it impossible to stably hold the wafer. 
SUMMARY OF THE INVENTION 
An object of the present invention is therefore to provide a substrate 
scrubbing device capable of more effectively preventing dust (or 
particles) and process solution from adhering to the lower surface of a 
substrate when the upper surface of the substrate is being scrubbed. 
Another object of the present invention is to provide a substrate scrubbing 
device capable of more stably holding the substrate even when the rotating 
speed of a spin chuck is accelerated for a start and decelerated for a 
stop. 
According to an aspect of the present invention, there can be provided a 
substrate scrubbing device comprising means for rotating a substrate 
together with a spin plate; means for holding the substrate so as to form 
a space between the spin plate member and a lower surface of the 
substrate; means for applying cleaning solution onto an upper surface of 
the substrate; means for cleaning the upper surface of the substrate by a 
rotating brush; and means for blowing solution onto the lower surface of 
the substrate; wherein a solution passage for the solution blowing means 
is formed in a drive shaft of the rotating means and communicated with the 
space between the spin plate and the lower surface of the substrate. 
Further, this substrate scrubbing device includes means for exhausting the 
space between the spin plate member and the lower surface of the substrate 
and an exhaust passage for this exhaust means is formed in the drive shaft 
for the rotating means. 
According to the substrate scrubbing device, process solution can be 
exhausted outside together with other solution through the exhaust passage 
even when process solution comes onto the lower surface of the substrate. 
According to another aspect of the present invention, there can be provided 
a substrate scrubbing device comprising means for rotating a substrate 
together with a spin plate member; means for holding the substrate in such 
a way that a space can be formed between the spin plate and the substrate; 
means for applying solution onto an upper surface of the substrate; means 
for scrubbing the upper surface of the substrate by a rotating brush; and 
an auxiliary assembly attached to the holder means to hold the substrate 
at the time when the rotation of the spin plate member is started and 
stopped. 
According to this second device, the auxiliary assembly is made operative 
to hold the substrate when the rotating speed of the holding means is 
accelerated for a start and decelerated for a stop. Its structure may be 
therefore optional, but it is preferable that the auxiliary assembly 
includes a rotating member arranged rotatable in relation to the holding 
means and urged in forward and backward directions, and holders each being 
swingably pivoted on the holding means and slidably engaged, at its one 
end, with the rotating member and having, at its other end, pressing 
pieces which are to be pressed against the rim of the substrate. 
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 
Some cases where the scrubbing device according to the present invention is 
used to resist-process semiconductor wafers will be described with 
reference to the accompanying drawings. 
As shown in FIG. 1, the resist process system has a load/unload section 20 
so-called a cassette station and a process section 30. Semiconductor 
wafers are carried between the sections 20 and 30 by carrying robots 23 
and 32. The load/unload section 20 includes a robot running passage 24. 
Cassettes 21 and 22 are mounted on the cassette station and wafers which 
are to be processed are housed in cassettes 21 and wafers which have been 
processed are housed in cassettes 22. The wafer carrying robot 23 has an 
arm for sucking and holding the wafer W, and it can move in an X axis 
direction along the running passage 24, in a Y axis direction, in a Z axis 
direction (or vertical direction) and in a direction .theta. (or rotating 
direction). 
An alignment stage 25 is arranged between the load/unload section 20 and 
the process section 30 and the wafer W is centered and transferred from 
the robot 23 to the robot 32 at the alignment stage 25. 
A passage 31 on which the robot 32 can run is arranged along the center 
line of the process section 30, extending from the alignment stage 25 in 
the X axis direction. The robot 32 has a main arm 33 movable in the Y and 
Z axes directions and also in the rotating direction .theta.. Adhesion, 
pre-baking and cooling units 34, 35 and 36 are arranged on one side of the 
running passage 31 and resist-coating and substrate-cleaning units 37 and 
38 on the other side thereof. 
As shown in FIG. 2, a horizontal base 2 of the substrate-cleaning unit 38 
is supported by four posts 3. A brush cleaner 5, an operation mechanism 6 
and a spin chuck mechanism 40 are arranged on the horizontal base 2. The 
operation mechanism 6 serves to move a jet nozzle 13 and a brush 42 in the 
X and Z axes directions. The jet nozzle 13 is attached to the front end of 
an arm 17, which is supported by a mechanism 15. The arm 17 can be 
extended in the Y axis direction and swung in the direction .theta. by the 
mechanism 15. 
The brush 42 is wound round a shaft 44 in a spiral. This spiral brush 42 
can make its contact area with the wafer W larger than the disk brush. In 
addition, it can make its contact pressure against the wafer W more 
uniform than the roll brush. It is made of nylon or mohair. The shaft 44 
is rotated round its center axis, extended in the Y axis direction and 
swung in the direction .theta. by a drive mechanism 41, which is connected 
to the operation mechanism 6 by a lifter base 43 and moved in the Z axis 
direction by the lifter base 43. The brush cleaner 5 serves to clean the 
brush 42 when the brush 42 is at its waiting position. 
As shown in FIG. 3, a motor power supply (not shown) of the drive mechanism 
41 is connected to the output side of a controller 80, by which the 
rotation number and the positioning of the brush 42 are controlled. A 
light-receiving sensor 72 is connected to the input side of the controller 
80 and a light-emitting sensor 71, a pump 57, a valve 59, a motor 60, 
nitrogen gas supply source 81 and an exhaust mechanism 83 to the output 
side thereof. The controller 80 includes circuit-designed CPU, ROM and RAM 
and it sends command signals according to a predetermined recipe to 
control the operation of the brush, the amount of solution supplied, the 
rotation number of the spin chuck the flow rate of gas supplied and the 
amount of gas exhausted. 
In FIG. 3, the brush 42 is contacted with the top surface of the wafer W on 
the spin chuck mechanism 40 and the jet nozzle 13 is positioned above the 
spin chuck mechanism 40. The jetting position of the jet nozzle 13 is 
shifted from that position of the brush 42 at which the brush 42 is 
contacted with the wafer W. The jet nozzle 13 is connected to a pure water 
containing tank 54 through a cleaning solution (or pure water) supply pipe 
58. A pump 57 and a valve 59 are attached to the cleaning solution supply 
pipe 58 and the flow rate and pressure of pure water 55 are controlled by 
this pump and valve. A heater 56 is arranged round the tank 54 to adjust 
the temperature of pure water 55. When heated pure water 55 is used, 
particles adhering to the surface of the wafer W can be more efficiently 
removed from the wafer W. In addition, the wafer W which has been washed 
and cleaned by heated pure water 55 can be dried for a shorter time. 
The spin chuck mechanism 40 will be described. 
A chuck section 51 of the spin chuck mechanism 40 has a disk-like spin 
plate 62, which is rotated by a motor 60. The spin plate 62 is enclosed by 
a case (not shown). Plural holding claws 63 are erected from the top and 
along the rim of the spin plate 62 and a clearance (or space) 52, 
substantially same in depth, is formed between the wafer W supported by 
the holding claws 63 and the spin plate 62. It is preferable that the 
clearance 52 has a depth of 1-3 mm. Each of the holding claws 63 has a 
small-diameter portion 63a on its top and the wafer W is contacted with 
these small-diameter portions 63a at its rim not to be shifted in 
position. 
A rotating shaft 61 is fixed to the spin plate 62 at its top portion and 
left free from (or not fixed to) a cylindrical member 64 at its lower end 
portion. It is supported, rotatable in the drive motor 60, by a pair of 
bearings 60a. A seal block 65 is connected to the underside of the 
cylindrical member 64 and the lower end portion of the rotating shaft 61 
is enclosed by the seal block 65. First and second chambers 67a and 67b 
are formed in the seal block 65. The cylindrical member 64 is fixed to the 
underside of the motor 60 by welding. 
The cylindrical member 64 and the seal block 65 are positioned relative to 
the rotating shaft 61 to have a clearance 66a between them. The motor 60 
is communicated with the first chamber 67a through this clearance 66a. 
Further, an outlet 84a of the first chamber 67a is communicated with the 
exhaust mechanism 83 through a pipe 84 to exhaust the motor 60 and the 
first chamber 67a. 
A labyrinth seal 66b is arranged between the first 67a and the second 
chamber 67b. An inlet 82a of the second chamber 67b is communicated with 
the gas supply source 81 through a pipe 82, through which nitrogen gas is 
supplied from the gas supply source 81 into the second chamber 67b. Air 
may be supplied instead of nitrogen gas. 
The rotating shaft 61 is made hollow. One end 82b of a passage 61a in the 
rotating shaft 61 is communicated with the second chamber 67b and the 
other end 61c thereof with the space 52 (or opened at the top of the spin 
plate 62). 
The wafer detecting sensors 71 and 72 are positioned to extend their 
optical axis along the passage 61a in the rotating shaft 61. A transparent 
plate 70 made of quartz glass is attached to the lower portion of the seal 
block 65 and when no wafer is mounted on the holding claws 63, beam light 
emitted from the sensor 71 is received by the sensor 72 through the 
transparent plate 70. 
A case where the above-described scrubbing device is used to clean the 
wafer W will be described. The wafer W is carried and mounted on the 
holding claws 63 by a forked arm 33. The motor 60 is driven to rotate the 
wafer W together with the spin plate 62. The brush 42 and the jet nozzle 
13 are moved above the wafer W and while spraying pure water onto the 
surface of the wafer through the jet nozzle 13, contaminating particles 
are removed from the surface of the wafer W by the brush 42. While 
introducing gas into the space or clearance 52 under the wafer, the first 
chamber 67a is exhausted. This prevents the cleaning solution or pure 
water from coming or adhering onto the lower surface of the wafer W. In 
addition, matters such as particles caused in the motor 60 are exhausted 
outside through the outlet 84a of the first chamber 67a. This prevents 
these matters from adhering onto the underside of the wafer W. 
As shown in FIGS. 4 and 5, a guide plate 90 may be arranged at the chuck 
section 51 of the spin chuck mechanism 40. It is positioned in the space 
52 and just above the open top 61c of the rotating shaft 61. It guides gas 
introduced through the open top 61c of the rotating shaft 61 to the 
peripheral surface of the underside of the wafer W. It is a little 
separated from the top of the spin plate 62. In short, three legs 91 are 
attached to its underside and they are fixed to a lower boss 62a by screws 
92. It is preferable in this case that the clearance 52 is in a range of 
1-3 mm and that the distance extending from the top of the spin plate 62 
to its underside is in a range of 1-1.5 mm. 
As shown in FIG. 5, three slits 62b are formed at the peripheral portion of 
the spin plate 62 to allow support claws 102 of a fork 100 of arm 33 to 
pass through the slits 62b. When the slits 62b and the support claws 102 
are combined in this manner, the form 100 which is transferring the wafer 
W onto the spin plate 62 can be prevented from interfering with the spin 
plate 62. 
Another spin chuck mechanism 40b of the double-pipe type which comprises 
the spin chuck rotating shaft 61 and a gas supply pipe 74 will be 
described referring to FIG. 6. 
The rotating shaft 61 of the spin chuck mechanism 40b is made hollow and 
the gas supply pipe 74 is coaxially passed through the hollow portion of 
the shaft 61. The lower end portion of the gas supply pipe 74 is fixed to 
a seal block 68, which is attached to the underside of the motor 60 and 
provided with upper and lower chambers 68e and 68b. A passage 68a 
extending from the lower chamber 68e is communicated with a passage 82a of 
the pipe 82 and then with the gas supply source 81. The upper chamber 68b 
is communicated with a passage 84a of the pipe 84 and then with the 
exhaust mechanism 83. 
The top of the gas supply pipe 74 is a little projected from the top 
surface of the spin plate 62 and opened in the space 52. A clearance 
passage 75 is formed between the hollow shaft 61 and the gas supply pipe 
74. This clearance passage 75 is communicated with both of the space 52 
and the upper chamber 68b. 
According to the spin chuck mechanism 40b which is a combination of gas jet 
and exhaust, ambient atmosphere around an upper end portion of the shaft 
61 is not sucked into the space 52, so that the amount of particles 
adhering to the lower surface of the wafer W can be reduced to a greater 
extent. This is because the lower area of the space 52 is exhausted 
through the passage 75. More specifically, ambient atmosphere around an 
upper end portion of the shaft 61 is sucked into the space 52 due to the 
so-called venturi effect. The lower area of the space 52 is exhausted 
through the passage 75, as described above. As a result, atmosphere is 
prevented from being introduced into the space 52, thereby making it 
difficult to contact the lower surface of the wafer. 
Further, the seal block 68 which is communicated with the motor 60 is 
positively exhausted. This also makes it difficult for particles caused by 
the bearings 60a to adhere to the underside of the wafer W. 
A further spin chuck mechanism 40c which is a variation of the mechanism 40 
will be described with reference to FIG. 7. 
In the case of the spin chuck mechanism 40c, solution is blown to the 
underside of the wafer W instead of gas. A bypass pipe 58a is communicated 
with the lower chamber 68e of the seal block 68 through the passage 68a. 
The bypass pipe 58a branches from a main pipe 58 through a cross valve 
59a. The main pipe 58 is communicated with the tank 54 in which pure water 
as contained. The pump 57 is attached to the main pipe 58 upstream the 
cross valve 59a and a valve 59b is attached to the bypass pipe 58a. In 
short, the pure water tank 54 is used as a common source for supplying 
pure water to both of the jet nozzle 13 and the pipe 74. 
According to the above-described scrubbing device, it can be made simpler 
in structure and smaller in size. In addition, the cleaning efficiency can 
be made higher. 
According to the above-described scrubbing device, the motor can be 
exhausted through the seal block. Dust and particles caused by the 
bearings can be thus prevented from adhering to the wafer W. 
Substrates which are to be scrubbed are not limited to semiconductor 
wafers. The scrubbing device of the present invention can also be applied 
to LCD substrates, photo-masks, ceramic substrates, compact disks and 
print substrates, for example. 
A second embodiment of the present invention will be described with 
reference to FIGS. 8 through 12. Description on same components as those 
of the first embodiment will be omitted. 
As shown in FIG. 8, the resist coating and scrubbing units 37 and 38 are 
arranged side by side on one side of the robot running passage 31. A spin 
chuck mechanism 200, the Jet nozzle 13 and a disk brush 202 are arranged 
in the scrubbing unit 38. 
As shown in FIG. 9, the horizontal base of the substrate scrubbing unit 38 
is supported by four posts 3. A brush cleaner 8, an operation mechanism 9 
and the spin chuck mechanism 200 are arranged on the horizontal base 2. 
The operation mechanism 9 serves to move the jet nozzle 13 and the disk 
brush 202 in the X and Z axes directions. The jet nozzle 13 is attached to 
the front end of the arm 17, which is supported by the mechanism 15. The 
arm 17 is extended in the Y axis direction and swung in the direction a by 
the mechanism 15. 
The disk brush 202 is attached to the front end of an operation arm 206 in 
such a way that it can rotate round its own axis and swing round a support 
rod 207 of the arm 206. A plurality of nylon or mohair fibers are planted 
on the underside of the disk brush 202. When it is at its waiting 
position, the disk brush 202 is cleaned by the brush cleaner 8. A 
ultrasonic cleaning nozzle may be used in addition to the disk brush 202. 
As shown in FIGS. 10 and 12, a spin plate 205 of the spin chuck mechanism 
200 is connected to the top of a hollow shaft 204 which is rotated by a 
drive motor (not shown). N.sub.2 gas is supplied from a gas supply source 
(not shown) into the hollow portion of the shaft 204. 
An auxiliary holder mechanism 215 is intended to hold the wafer W in such a 
way that the wafer W is not shifted to and fro on the spin plate 205 when 
the spin plate 205 is accelerated for a start and decelerated for a stop. 
The auxiliary holder mechanism (or assembly) 215 includes a rotator 216, 
springs 217 and holders 218. The rotator 216 as located under the spin 
plate 205 and rotatably fitted onto a rotating block 204a through a 
bearing 204b. The rotating block 204a is fixed to the shaft 204. The 
springs 217 urge the rotator 216 to neutral position. Each of the holders 
218 is swingably engaged, at its one end, with the rotator 216 by a pin 
214. Two pressing pieces 219a and 219b are attached to the other free end 
of each of the holders 218. 
An arc groove 217a coaxial to the rotator 216 is formed in the top of the 
rotator 216 and a base or center pin 212 is inserted into the arc groove 
217a. The base pin 212 is passed through the spin plate 205. Springs 217 
are arranged on both sides of the base pin 212 to keep the rotator 216 
neutral to rotate forward or backward. 
Each of the holders 218 is a plate member pivoted on a fulcrum pin 213 to 
swing in a horizontal plane. The fulcrum pin 213 is attached to the spin 
plate 205. A slit 218a is formed at that end of the holder 218 which is 
nearer the rotating center of the plate 205, and the pin 214 is inserted 
in the slit 218a. Two pressing pieces 219a and 219b which are to be 
pressed against the rim of the wafer W are erected from the other end of 
the holder 218. They are loosely fitted into an arc guide hole 205b formed 
in the spin plate 205 along the rim thereof. These three holders 218 
symmetrical to the center of the spin plate 205 are added to the spin 
plate 205. 
It will be described how the above-described spin chuck mechanism 200 is 
operated. 
When the shaft 204 is driven in a direction R, inertial force in a 
direction A (reverse to the direction R) acts on the rotator 216 and the 
holders 218 are thus swung. Free ends (or pressing pieces) 219a of the 
holders 218 are pressed against the rim of the wafer W, as shown in FIG. 
10, to hold the wafer W not to shift to and fro in the plane of the spin 
plate 205. When the rotating speed of the shaft 204 becomes certain, the 
holders 218 are returned to neutral positions by the springs 217, so that 
the pressing pieces 219 of the holders 218 can be released from the rim of 
the wafer W. 
The wafer W is rotated together with the spin plate 205. The disk brush 202 
and the jet nozzle 13 are positioned above the wafer W. While jetting 
cleaning solution onto the surface of the wafer W through the jet nozzle 
13, the disk brush 202 is contacted with the surface of the wafer W. The 
disk brush 202 is rotated round its own center axis and also round the 
support rod 207 when the wafer W is being scrubbed. Contaminating 
particles are thus removed from the surface of the wafer W. 
This scrubbing process may be achieved using only the jet nozzle 13 wherein 
cleaning solution is jetted onto the wafer W through the jet nozzle 13, or 
using only the disk brush 202 wherein the wafer W is scrubbed by the disk 
brush 202 while supplying cleaning solution near the brush 202. Or both of 
them may be used at the same time or alternately, depending upon the kind 
of substrates to be scrubbed and the extent to which substrates must be 
scrubbed. During this scrubbing process, N.sub.2 gas is supplied to the 
lower surface of the wafer W, flowing particularly to the peripheral 
portion of the wafer W. This prevents cleaning solution from coming or 
adhering onto the lower surface of the wafer W. 
When the rotating speed of the shaft 204 is decelerated, inertial force in 
a direction B (same as the direction R) acts on the rotator 216 and the 
holders 218 are thus swung. Free ends (or pressing pieces) 219b of the 
holders 218 are pressed against the rim of the wafer W, as shown in FIG. 
11, to hold the wafer W not to shift to and from in the plane of the spin 
plate 205. When rotations of the shaft 204 and the spin plate 205 are 
stopped, the holders 218 are returned to neutral positions by the springs 
217 and the pressing pieces 219b are released from the rim of the wafer W. 
According to the above-described spin chuck mechanism 200, the wafer W can 
be more reliably held in the plane of the spin plate 205 even if the spin 
plate 205 is abruptly accelerated or decelerated. The wafer W can be thus 
cleaned for a shorter time and the efficiency of processing wafers can be 
made higher accordingly. 
Although three holders have been attached to the spin plate 205 in the 
above-described case, four or more holders 318 may be attached to it. 
According to the above-described mechanism 200, any changes in the rotating 
speed of the shaft 204 at the rotation start or stop of the wafer W can be 
more reliably transmitted to the holders 218. This enables the wafer a to 
be more stably and reliably held in the plane of the spin plate 205. 
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.