U.S. patent application number 11/768119 was filed with the patent office on 2007-10-18 for wafer edge with light sensor.
This patent application is currently assigned to ASM America, Inc.. Invention is credited to David A. Beginski, Richard Crabb, James Donald.
Application Number | 20070242281 11/768119 |
Document ID | / |
Family ID | 33417788 |
Filed Date | 2007-10-18 |
United States Patent
Application |
20070242281 |
Kind Code |
A1 |
Beginski; David A. ; et
al. |
October 18, 2007 |
WAFER EDGE WITH LIGHT SENSOR
Abstract
An apparatus for detecting the presence of a substrate that is
carried by an end effector of a substrate handling assembly
positioned within a substrate processing system comprises a
receiving member that is coupled to an end effector and a light
sensor that is operatively coupled to the receiving member and is
configured to detect an amount light transmitted by the receiving
member. In a modified embodiment, the apparatus also includes a
transmitting member that receives light from a light source and is
also coupled to the end effector.
Inventors: |
Beginski; David A.;
(Gilbert, AZ) ; Crabb; Richard; (Phoenix, AZ)
; Donald; James; (Phoenix, AZ) |
Correspondence
Address: |
KNOBBE, MARTENS, OLSEN & BEAR LLP
2040 MAIN STREET
FOURTEENTH FLOOR
IRVINE
CA
92614
US
|
Assignee: |
ASM America, Inc.
Phoenix
AZ
|
Family ID: |
33417788 |
Appl. No.: |
11/768119 |
Filed: |
June 25, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10439393 |
May 16, 2003 |
7235806 |
|
|
11768119 |
Jun 25, 2007 |
|
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Current U.S.
Class: |
356/622 ;
250/559.29 |
Current CPC
Class: |
H01L 21/67259
20130101 |
Class at
Publication: |
356/622 ;
250/559.29 |
International
Class: |
G01N 21/86 20060101
G01N021/86 |
Claims
1. An apparatus for detecting the presence of a substrate that is
carried by an end effector of a substrate handling assembly
positioned within a substrate processing system, the apparatus
comprising: a first receiving member that is coupled to the end
effector such that the first receiving member moves with the end
effector; a light sensor that is operatively coupled to the first
receiving member and is configured to detect an amount of light
received by the first receiving member; and a control system
operatively coupled to the light sensor and configured to indicate
the presence of the substrate based upon the amount of light
detected by the light sensor; wherein a tip portion of the first
receiving member is positioned such that, when the substrate is
properly carried by the end effector in a first position, the
substrate substantially blocks ambient light from being received by
the tip portion of the first receiving member; a first transmitting
member that is coupled to the end effector such that the first
transmitting member moves with the end effector; and a light source
that is operatively coupled to the first transmitting member and is
configured to transmit an amount of light to the first transmitting
member.
2. The apparatus as in claim 1, wherein the apparatus is positioned
within a sealed environment and the apparatus further comprises a
wireless data transmitter that is positioned in the sealed
environment and is configured to transmit information to a point
beyond the sealed environment.
3. The apparatus as in claim 1, further comprising a photoelectric
cell configured to provide power to the light sensor.
4. The apparatus as in claim 1, further comprising a photoelectric
cell configured to provide power to the control system.
5. An apparatus for detecting the presence of a substrate that is
carried by an end effector of a substrate handling assembly
positioned within a substrate processing system, the apparatus
comprising: a first receiving member that is coupled to the end
effector such that the first receiving member moves with the end
effector; a light sensor that is operatively coupled to the first
receiving member and is configured to detect an amount of light
received by the first receiving member; a control system
operatively coupled to the light sensor and configured to indicate
the presence of the substrate based upon the amount of light
detected by the light sensor; a first transmitting member that is
coupled to the end effector such that the first transmitting member
moves with the end effector; and a light source that is operatively
coupled to the first transmitting member and is configured to
transmit an amount of light to the first transmitting member;
wherein, when the substrate is being properly carried on the end
effector, at least a portion of the amount of light transmitted by
the first transmitting member is reflected off of a lower surface
of the substrate at an angle and is received by the first receiving
member to indicate the presence of the substrate on the end
effector.
6. The apparatus as in claim 5, wherein the first receiving member
and the first transmitting member have a tip portions that are
generally perpendicular to elongated portions of the first
receiving member and the first transmitting member.
7. The apparatus as in claim 5, further comprising a photoelectric
cell configured to provide power to the apparatus.
8. An apparatus for detecting the presence of a substrate that is
carried by an end effector of a substrate handling assembly
positioned within a substrate processing system, the apparatus
comprising: a first receiving member that is coupled to the end
effector such that the first receiving member moves with the end
effector; a second receiving member that is coupled to the end
effector such that the second receiving member moves with the end
effector; a light sensor that is operatively coupled to the first
receiving member and the second receiving member and is configured
to detect an amount of light transmitted by the first and second
receiving members; a first transmitting member that is coupled to
the end effector such that the first transmitting member moves with
the end effector; a second transmitting member that is coupled to
the end effector such that the second transmitting member moves
with the end effector; a light source that is operatively coupled
to the first and second transmitting members and is configured to
transmit an amount of light through the first and second
transmitting members; and a control system operatively coupled to
the light sensor and configured to indicate the presence of the
substrate based upon the amount of light detected by the light
sensor; wherein, when the substrate is being properly carried on
the end effector, at least a portion of the amount of light
transmitted by the first transmitting member is reflected off of a
lower surface of the substrate at an angle and is received by the
first receiving member to indicate the presence of the substrate on
the end effector.
9. A method for monitoring the position of a substrate within a
substrate processing system, comprising: providing a first
receiving member that is coupled to an end effector of the
substrate processing system; providing a light detection sensor,
which is operatively coupled to the first receiving member;
detecting the presence of a substrate when the first receiving
member receives a first amount of light; and detecting the absence
of a substrate when the first receiving member receives a second
amount of light that is greater than the first amount of light;
wherein, when the substrate is present, a lower surface of the
substrate reflects light at an angle from a transmitting member
into the first receiving member.
10. A method for monitoring the position of a substrate within a
substrate processing system, comprising: providing a first
receiving member that is coupled to an end effector of the
substrate processing system; providing a light detection sensor,
which is operatively coupled to the first receiving member;
providing a first transmitting member that is also coupled to an
end effector of the substrate processing system; providing a light
source, which is operatively coupled to the first transmitting
member; detecting the presence of a substrate when the first
receiving member receives light from the first transmitting member
that is reflected off of a lower surface of the substrate at an
angle; and detecting the absence or misalignment of a substrate
when the first receiving member does not receive light from the
first transmitting member that is reflected off of a lower surface
of the substrate.
11. A method as in claim 10, further comprising: providing a second
receiving member that is coupled to the end effector; providing a
second transmitting member that is also coupled to an end effector;
detecting the absence or misalignment of a substrate when the first
receiving member does not receive light from the first transmitting
member and the second receiving member does not receive light from
the second transmitting member; and detecting the position of a
substrate when the first receiving member receives light from the
first transmitting member that is reflected off of the substrate
and the second receiving member does not receive light from the
second transmitting member.
12. A method for monitoring the position of a substrate within a
substrate processing system, comprising: providing a first
receiving member that is coupled to an end effector of the
substrate processing system; providing a second receiving member
that is coupled to the end effector; providing a light detection
sensor, which is operatively coupled to the first receiving member
and the second receiving member; providing a first transmitting
member that is also coupled to an end effector of the substrate
processing system; providing a second transmitting member that is
also coupled to an end effector; providing a light source, which is
operatively coupled to the first transmitting member and the second
transmitting member; detecting the absence or misalignment of a
substrate when the first receiving member does not receive light
from the first transmitting member that has be been reflected off
of a lower surface of the substrate and the second receiving member
does not receive light from the second transmitting member that has
be been reflected off of the lower surface of the substrate;
detecting the position of a substrate when the first receiving
member receives light from the first transmitting member that is
reflected off of the lower surface of the substrate at an angle and
the second receiving member does not receive light from the second
transmitting member that has been reflected off of the lower
surface of the substrate; and detecting the misalignment of a
substrate when the first receiving member receives light from the
first transmitting member that is reflected off of the lower
surface of the substrate and the second receiving member receives
light from the second transmitting member that is also reflected
off of the lower surface of the substrate.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of U.S.
application Ser. No. 10/439,393 filed on Apr. 10, 2003, issued as
U.S. Pat. No. 7,235,806 on Jun. 26, 2007, which is hereby
incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This present invention relates to substrate processing and,
in particular, to methods and apparatus for detecting the presence
or position of a substrate located within a substrate processing
system.
[0004] 2. Description of the Related Art
[0005] Semiconductor devices, such as transistors, diodes, and
integrated circuits, are typically fabricated on a thin slice of
semiconductor material, termed a substrate or wafer. The substrate
is fabricated within a substrate processing system, which typically
includes one or more load locks, a wafer handling module and one or
more processing modules. The one or more load locks provide a
substantially particle free environment from which substrates may
be selectively withdrawn into the substrate handling module. The
substrate handling module typically includes a substrate handler,
which is configured to move substrates to/from the one or more load
locks and to/from the one or more processing modules.
[0006] There are several general problems that are associated with
prior art substrate processing stations. For example, as the
substrate is moved within the processing station, the substrate can
become misaligned or mispositioned for various reasons. Such
mispositioning can result in damage to the substrate as it is moved
within the processing station and/or errors in the fabrication
process if the mispositioning occurs within a processing module. As
such, some substrate processing system include several sensors to
monitor the position of the substrate position. Each sensor adds to
the complexity and cost of the processing system. These sensors are
also typically difficult to maintain and require frequent
alignment.
SUMMARY OF THE INVENTION
[0007] A need therefore exists for a more simple and accurate
method for monitoring the position of the substrate within a
processing system.
[0008] One embodiment of the present invention is an apparatus for
detecting the presence of a substrate that is carried by an end
effector of a substrate handling assembly positioned within a
substrate processing system. The apparatus comprises a first
receiving member that is coupled to the end effector such that the
first receiving member moves with the end effector. A light sensor
is operatively coupled to the first receiving member and is
configured to detect an amount light transmitted by the first
receiving member. A control system is operatively coupled to the
light sensor and configured to indicate the presence of the
substrate based upon the amount of light detected by the light
sensor.
[0009] Another embodiment is a method for monitoring the position
of a substrate within a substrate processing system. The method
involves providing a first receiving member that is coupled to an
end effector of the substrate processing system. A light detection
sensor is provided and is operatively coupled to the first
receiving member. The presence of a substrate is detected when the
first receiving member receives a first amount of light. The
absence of a substrate is detected when the first receiving member
receives a second amount of light that is greater than the first
amount of light.
[0010] Another embodiment is a method for monitoring the position
of a substrate within a substrate processing system. The method
comprises providing a first receiving member that is coupled to an
end effector of the substrate processing system. A light detection
sensor is operatively coupled to the first receiving member. A
first transmitting member is provided and is also coupled to an end
effector of the substrate processing system. A light source is
provided and is operatively coupled to the first transmitting
member. The presence of a substrate is detected when the first
receiving member receives light from the first transmitting member
that is reflected off of the substrate. The absence or misalignment
of a substrate is detected when the first receiving member does not
receive light from the first transmitting member.
[0011] Further aspects, features and advantages of the invention
will become apparent from the following description of the
preferred embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] These and other features, aspects and advantages of the
present invention will now be described with reference to the
drawings of preferred embodiments which are intended to illustrate
and not to limit the invention. The drawings comprising
[0013] FIG. 1 a schematic top plan view of a substrate processing
system.
[0014] FIG. 2 is a bottom plan view of an end effector of the
substrate processing system and a portion of a substrate detection
system having certain features and advantages according to the
present invention.
[0015] FIG. 3 is a front view of the end effector and substrate
detection system of FIG. 2.
[0016] FIG. 4 is a top plan view of a light pipe of the substrate
detection system of FIG. 2.
[0017] FIG. 5 is a schematic illustration of the substrate
detection system of FIG. 2.
[0018] FIG. 6A-C are schematic illustrations showing the operation
of the substrate detection system.
[0019] FIG. 7A-C are schematic illustrations showing the operation
of a modified embodiment of the substrate detection system.
[0020] FIG. 8 is a top plan view of the end effector with a portion
of another modified embodiment of a substrate detection system.
[0021] FIG. 9 is a front view of the end effector and substrate
detection system of FIG. 8.
[0022] FIG. 10 is a top plan view of a light pipe of the substrate
detection system of FIGS. 8 and 9.
[0023] FIG. 11 is a schematic illustration of the substrate
detection system of FIGS. 8 and 9.
[0024] FIGS. 12A and 12B are schematic illustrations of a front
view of the detection system of FIGS. 8 and 9 showing the operation
the substrate detection system.
[0025] FIGS. 13A-C are schematic illustrations of a top view of the
detection system of FIGS. 8 and 9 showing the operation of the
substrate detection system.
[0026] FIG. 14 is a schematic illustration of another modified
embodiment of a substrate detection system.
[0027] FIG. 15 is a schematic illustration of still another
modified embodiment of a substrate detection system.
[0028] FIG. 16 is a schematic illustration of a temperature sensor
system.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0029] FIG. 1 illustrates an exemplary substrate processing system
10 that comprises two load locks 12, a substrate handling module
14, and two substrate processing modules 16. The substrate handling
module 14 comprises a housing 18, which defines a substrate
handling chamber 20. The substrate handling chamber 20 is
preferably substantially closed and under vacuum. However, in
modified embodiments, the substrate handling chamber can be kept a
higher pressures (e.g., atmospheric).
[0030] The load locks 12 can be adapted for holding, among other
things, a cassette of substrates, a plurality of single substrates
and/or a single substrate. The load locks 12 are connected to the
substrate handling module 14 by an opening, which is selectively
opened and closed by a gate valve 22. In a similar manner, the
processing modules 16 are connected to the substrate handling
chamber 18 by openings, which are also selectively opened and
closed by gate valves 24.
[0031] A substrate handler 26 is positioned within the substrate
handling chamber 20. The substrate handler 26 is configured to
transfer a substrate 28 to, from and between the load locks 12 and
the processing modules 16. The substrate handler 26 includes an end
effector 30, which is configured to fit between the openings that
connect the load locks 12 and processing chambers 16 to the
substrate handling module 14. The substrate handler 26 also
includes a robot arm assembly 32. The robot arm assembly 32 is
mounted to a support member (not shown) and can control movement of
the end effector 30 in any manner.
[0032] As shown in FIGS. 2 and 3, in the illustrated embodiment,
the end effector 30 comprises a simple paddle or spatula, which
supports the substrate 28 by contacting a lower surface 36 of the
substrate 28 with an upper surface 38 of the paddle 30. The paddle
30 in some embodiments may be made of quartz so that it can engage
a substrate at high temperatures (e.g., above 1000 degrees
Celsius). Of course, other suitable materials may be used.
[0033] In the embodiments illustrated herein and described below,
the substrate detection system 40 is shown with a paddle-type end
effector 30. However, it should be appreciated that certain
features and advantages of the present invention can be used with
other types of end effectors 30. For example, the end effector may
be a gridded type spatula as described in U.S. Pat. No. 6,331,023,
a forked type end effector as described in U.S. Pat. No. 6,293,749,
a Bernoulli wand as described in U.S. Pat. No. 6,242,718, an edge
grip type end effector, or a vacuum grip end effector. The
detection system 40 may also be used with a substrate carrier such
as the substrate carrier described in U.S. patent application Ser.
No. 09/256,743.
[0034] With reference to FIGS. 2-5, the end effector 30 preferably
includes a substrate detection system 40 having certain features
and advantages according to the present invention. In the
illustrated embodiment, the detection system 40 comprises a
detection portion 42 (see FIGS. 2 and 3) and a
receiving/transmitting portion 44 (see FIG. 5). The detection
portion 42 is preferably configured such that it moves with the end
effector 30. In contrast, the receiving/transmitting portion 44 can
be located on the robot arm assembly 32 and/or the support member.
In the illustrated embodiment, the detection portion 42 and the
receiving/transmitting portion receive and transmit light through
light pipes, which may have a number of straight and bent sections
to allow receiving/transmitting surfaces to be at the appropriate
positioned as will be explained in more detail below.
[0035] In the illustrated embodiment, the detection portion 42
comprises a transmitting light pipe 48 and a receiving light pipe
50. Both light pipes 48, 50 are preferably formed from clear
optical material and form a wave guide for transmitting light,
preferably visible light. In the illustrated embodiment, the
transmitting light pipe 48 includes a straight section 54, a bent
section 56 and a tip portion 58 (see also FIG. 2). The straight
section extends along a first longitudinal side 60 of the end
effector 30. The curved section 56 preferably curves about a first
front corner 62 of the end effector 30 such that the tip portion 58
lies in front of the end effector. In a similar manner, the
receiving light pipe 50 of the illustrated embodiment also includes
a straight section 64, a bent section 66 and a tip portion 68. The
straight section 64 extends along a second longitudinal side 70 of
the end effector 30. The bent section 66 curves about a second
front corner 72 of the end effector 30 such that the tip portion 68
of the receiving light pipe 50 also lies in front of the end
effector 30.
[0036] In the illustrated embodiment, the tip portions 58, 68 are
located in front of the end effector 30 and the straight portions
54, 64 extend along the longitudinal sides 60, 70 of the end
effector 30. However, it should be appreciated that the illustrated
configuration of the bent and straight portions are merely
exemplary. For example, in one modified embodiments, one or both
tip portions 58, 68 can be located on the sides of the end effector
30. In another embodiment, the straight portions 54, 64 can be
positioned underneath the end effector 30. In still another
embodiments, the light pipes 48, 50 can be located adjacent to each
other.
[0037] With reference to FIG. 4, the tip portions 58, 68 include
transmitting/receiving surfaces 71. As shown in FIG. 3, the tip
portions 58 are angled such that the transmitting/receiving
surfaces point towards the lower surface 36 of the substrate 28
that is properly positioned on the end effector 30. More
specifically, the tip portions 58, 68 are orientated such that a
light beam emanating from the transmitting light pipe 48 will be
reflected off of the lower surface 36 of the substrate 28 and be
collected or received by the receiving light pipe 50.
[0038] As seen in FIG. 5, in the illustrated embodiment, the
straight section 54 of the transmitting light pipe 48 is
operatively coupled to a connecting member 74, which preferably
comprises a flexible light transmitting material, such as, for
example, a fiber optic cable. The connecting member 74 is, in turn,
connected to a light source 76. In one embodiment, the light source
76 is a 0.5 mW laser with a wave length of approximately 689
nanometers and in another embodiment the light source is a 48 Watt
quartz lamp. A lens 78 is preferably provided on the flexible
member 74 between the interface be the connecting member 74 and the
transmitting light pipe 48 for gathering light transmitted by the
connecting member 74.
[0039] In a similar manner, in the illustrated embodiment, the
straight section 64 of the receiving light pipe 50 is connected to
a second connecting member 80, which also preferably comprises a
flexible light transmitting material, such as, for example, a fiber
optic cable. As with the first connecting member 74, the second
connecting member 80 includes a lens 82 at the interface with the
receiving light pipe. The second connecting member 80 is connected
to a light sensor 84 (e.g., a photo cell sensor), which is
preferably operatively connected to a control system 86, as will be
explained in more detail below.
[0040] With reference to FIGS. 6A-C, the operation of the detection
system 40 will now be described. In FIG. 6A, the substrate 28 is
properly positioned on the end effector 30. The tip portions 58, 68
of the transmitting and receiving light pipes 48, 50 are orientated
such the light 88 generated by the light source 76 (FIG. 5) and
emitted from the transmitting light pipe 48 is reflected off the
substrate 28 and received by the receiving light pipe 50. The light
is transmitted through the receiving light pipe 50 and the flexible
member 80 and detected by light sensor 84 (FIG. 5), which plight
pipeuces an appropriate signal to the control system 68 (FIG. 5) to
indicate that the substrate 28 is present and in the proper
position.
[0041] In FIG. 6B, the substrate 28 is improperly positioned on the
end effector 30. With the substrate 28 in this position, the light
88 emitted by the transmitting light pipe 48 is not received by the
receiving light pipe 50 because it is reflected at an incorrect
angle. As such, no light or insufficient light is detected by the
light sensor 84 (FIG. 5) and an appropriate signal or lack of
signal can be sent to the control system 86 (FIG. 5) indicating
that the substrate 28 is improperly aligned. In a similar manner,
as shown FIG. 6C, when a substrate 28 is not positioned on the end
effector 30, the light 88 emitted by the transmitted light pipe 48
is not reflected and is not received by the receiving light pipe
50. The light sensor 84 (FIG. 5), therefore, does not receive a
light signal and an appropriate signal can be sent to the control
system 86 (FIG. 5).
[0042] In a modified embodiment, the end effector 30 can be
provided with one or more additional pairs of transmitting and
receiving light pipes. The additional pairs can be used in
combination with the transmitting and receiving light pipes
described above to determine the position of the substrate on the
end effector 30. That is, the additional pair can be used to
determine the edge of the substrate 28.
[0043] For example, as shown in FIGS. 7A, a second pair 90 of
transmitting and receiving light pipes 48', 50' can be spaced
further from the tip of the end effector 30. Though not
illustrated, it will be understood that each of the pairs ins
angled upwardly to bounce and receive light off the wafer bottom
surface, as illustrated in FIGS. 6A-C. When no wafer is present, as
illustrated in FIG. 7A, neither of the receiving light pipes 50,
50' receives light and thus the control system 86 (FIG. 5) would
indicate that a substrate is not present. When a substrate 28 is
present as shown in 7B, the receiving light pipe 50 of the first
pair 91 receives reflected light while the receiving light pipe 50'
of the second pair 90 does not. Such a situation indicates that a
substrate 28 is present on the end effector 30 and is in a position
wherein the edge 92 of the substrate 28 lies between the first and
second pairs of light pipes 91, 90. When the substrate 28 is
positioned as illustrated in FIG. 7C, the receiving light pipes 50,
50' of both pairs 91, 90 receive reflected light. Such a situation
indicates that the substrate 28 is present and that the edge 92 of
the substrate 28 is located past the second pair of light pipes
90.
[0044] It should be noted that, in the above-described embodiments,
the light sensor 84 (FIG. 5) can be configured such that it is
powered (i.e., generates electricity) from the light received from
the light source 76. Such an arrangement eliminates the need for a
power source (e.g., a battery) for the light sensor 84.
[0045] FIGS. 8-11 illustrate another embodiment of a substrate
detection system 100 having certain features and advantages
according to the present invention. The illustrated detection
system 100 comprises a shadow detection portion 102, that as with
the previous embodiment, is configured to move with the end
effector 30.
[0046] As with the previous embodiment, the detection portion 102
comprises a light pipe that is preferably formed from optically
transparent material that forms a wave guide for transmitting light
(preferably visible light) as will be explained below. In the
illustrated embodiment, the detection portion 102 includes a
straight section 106 and a tip portion 108, which is best seen in
FIG. 10. As shown, in FIG. 10, the tip portion 108 preferably
comprises a well-polished face 110 that forms approximately a 45
degree angle with respect to a longitudinal axis 112 of the
elongated portion 106. The tip portion 108 is configured to detect
a shadow as will be explained in more detail below. As best seen in
FIGS. 8 and 9, in the illustrated embodiment, the tip portion 108
is generally located near a front end 114 of the end effector 30.
However, this particular position is merely exemplary. For example,
the tip portion 108 may be located on along a side 116 of the end
effector 30. In still other embodiments, the elongated portion 106
may extend under the end effector 30. The elongated portion 106 may
also be bent, for example, in a manner as shown FIGS. 2 and 3.
[0047] With reference now to FIG. 11, the elongated portion 106 is
preferably connected to a connecting member 120, such as the
flexible connecting members described above. The flexible
connecting member 120 is connected to a photo cell or light sensor
122, which is preferably operatively connected to a control system
124 as will be explained in more detail below. The flexible
connecting member 120 preferably includes a lens 126 at the
interface between the flexible connecting member 120 and the
elongated portion 106.
[0048] The operation of the detection system 100 will now be
described with reference to FIGS. 12A and 12B. In FIG. 12A, the
substrate 28 is positioned on the end effector 30. The tip portion
108 of the detection portion 102 is under the substrate 28. As
such, the substrate 28 blocks the light 128 (e.g., visible light)
from being received by the detection portion 102. That is, the tip
portion 108 is located in the "shadow" of the substrate 28. As
such, no light or a very small amount light is being received by
the tip portion 108 and no or a very small amount of light is
transmitted to the light sensor 122. The control system 124 (FIG.
11) can be calibrated to interpret such a situation as indicating
that a substrate is present on the end effector 30.
[0049] The light 128 can be ambient light (i.e., light typically
present in the processing system 10) or light from a supplemental
light source (i.e., a light source added specifically to aid the
detection system 100). The ambient light or supplemental light
source may be positioned within or outside the processing system 10
(FIG. 1). In the embodiments where the ambient or supplemental
light is positioned outside the processing system 10, the
processing system 10 may include windows for allowing the ambient
or supplemental light to pass into the processing or handling
chambers 20.
[0050] In FIG. 12B, there is no substrate 28 on the end effector
30. As such, the tip portion 108 is no longer in the "shadow" of
the substrate 28. The tip portion 108, therefore, can receive
ambient light 128 or light from a supplemental light source. Such
light is transmitted to the light sensor 122, indicating that a
substrate is not present.
[0051] In a modified embodiment, the end effector can be provided
with one or more additional shadow detection portions. The shadow
detection portions can be used in combination to determine the
position of a substrate on the end effector in a manner similar to
that described above.
[0052] For example, as shown in FIG. 13A, the end effector 30
includes a second shadow detection portion 130 that is be distanced
further from the tip of the end effector as compared to the first
detection portion 102. While not shown, the tip can be angled as
described with respect to FIG. 10. When a substrate is absent as
illustrated in FIG. 13A, both shadow detection portions 102, 130
receive light and thus the control system indicates the absence of
a substrate. When a substrate 28 is positioned as shown in 13B, the
first shadow detection portion 102 is under the shadow of the
substrate 28 while the second detection portion 130 receives light.
Such a situation indicates that a substrate 28 is present on the
end effector 30 and that the edge 132 of the substrate is located
between the tip portions of the first and second shadow detection
portions 102, 130. When the substrate 28 is positioned as
illustrated in FIG. 13C, the tips of the shadow detection portions
102, 130 are both under the shadow of the substrate 28. This
situation indicates that the substrate 28 is present and that the
edge 132 of the substrate 28 is positioned beyond the tip of the
second shadow detection portion 130.
[0053] In another modified embodiment, the detection systems 100 of
FIGS. 8 or 13A can include an ambient light sensor 136 (See FIG.
14). The ambient light sensor 136 can be positioned on the end
effector 30 such that it is not affected by the presence or absence
of a substrate. In other embodiments, the ambient light sensor 136
can be positioned on one or more stationary portions of the
substrate processing system 10 (FIG. 1) or on a portion of the
substrate handler 26 (FIG. 1). As shown in FIG. 14, the ambient
light sensor 136 is preferably connected by a member 138 to a
second light sensor 167, which is also connected to the control
system 124. The presence or absence of a substrate can therefore be
determined by comparing the signals of the first light sensor 22 to
second light sensor 167. Such an arrangement reduces errors that
may be associated with changes in the ambient light and reduces the
time necessary to calibrate the detection system.
[0054] The embodiments described above have several advantages as
compared to prior art substrate detection systems. For example,
prior art substrate detection systems typically require multiple
sensors to sense the position of the substrate as the substrate is
moved between the load locks, the substrate handling module and the
processing modules. In the illustrated embodiments, the detection
portions of the detection system preferably are mounted onto and
move with the end effector. This arrangement reduces the need for
multiple sensors and thereby results in fewer parts, less
installation time and less maintenance time. In addition, the
detection portions preferably are made of quartz, which can
withstand temperatures up to about 1100 degrees Celsius. As such,
the detection portions may even be inserted into the processing
modules of the substrate processing system. In contrast, mirrors
and electrical sensors, which are often used in prior art detection
systems, typically cannot be inserted in the processing modules due
to the high temperatures.
[0055] FIG. 15 illustrates another embodiment of a substrate
detection system wherein like numbers are used to refer to parts
similar to those of FIG. 5. In this embodiment, the detection
system 150 includes an internal power source 152 and a wireless
transmission device 154. As will be explained in more detail below,
the wireless transmission device 154 can be used to transmit
information regarding the position of the substrate between a
sealed processing environment 153 an outer clean room or gray room
157, which is separated by a wall 155 from the sealed processing
environment 153. That is, the information is transmitted through
the walls 155 without the need for wires that extend through such
walls 155. With reference to FIG. 1, in the illustrated embodiment,
the wall 155 corresponds to the walls of the substrate processing
system 10 (i.e., the walls of the load locks 12, substrate handling
module 14, and processing chambers 20). As such, the sealed
processing environment 153 is the space within the processing
system 10, which is surrounded, at least partially, by the outer
clean room or gray room 157.
[0056] In a preferred embodiment, the internal power source 152
comprises a photoelectric cell or "solar" cell, which can convert
ambient light or light from a supplemental light source to
electricity. The electricity generated by the internal power source
152 can be used to power the light source 76, the light detection
device 84, and/or the control system 86, and/or the transmission
device 154. The signals from the control system are preferably
transmitted by the wireless communication device 154 to a more
comprehensive substrate processing control system 156, which is
preferably located outside or external to the sealed environment
153 (i.e., the substrate processing system 10). The signals can be
used by the substrate processing control system 156 to monitor the
position of the substrate as it moves through the processing system
10. The wireless communication device 154 is also preferably
powered by the power source 152. In one embodiment, the wireless
communication device 154 is a low power IR transmitter. In such an
embodiment, the wall 155 preferably includes a window through which
the IR signal can be transmitted. In another embodiment, the
wireless communication device 154 is a low power RF transmitter.
Preferably, the detection system 150 also includes a regulator and
a storage cap battery that can be charged by the solar cell (power
source) 152 to provide power during periods of darkness.
[0057] The embodiment described above has several advantages. For
example, as compared to an external power source (e.g., a direct
electrical connection), there are no physical connections (e.g.,
wires) between the external power source and the components of the
detection system. Such wires increase the complexity of the system
and may become damaged during the operation of the wafer handler.
Wire movement may also cause particle generation and require
additional seals in the processing system. Other internal power
sources, e.g., batteries, require frequent downtime to open the
processing system 10 and replace or maintain the power source when
the power is drained. The wireless communication device also
eliminates physical connections (e.g., wires) between the substrate
detection system 150 and the substrate control system 160, which
further reduces the complexity of the detection system 150. In
addition, the processing system can be retrofitted with additional
sensors without adding additional wires, which can create more
particle generation.
[0058] It should be appreciated that certain features of the system
150 described above can also be used with the embodiments described
with reference to FIGS. 1-14. Moreover, in certain embodiments, the
internal power source 152 may be used without the wireless
communication device 154 and in other embodiments, the wireless
communication device 154 may be used without the internal power
source 152.
[0059] It should also be appreciated that the internal power source
and/or the wireless communication device may be used to transmit
information between devices in the sealed processing environment
and the outer room. In particular, an internal power source and/or
a wireless communication device can be mounted on other devices
that move within the sealed substrate processing environment apart
from the substrate detection system described above. In other
embodiments, the internal power source and/or the wireless
communication device described above may be used with sensors on
other devices or other moving parts within the sealed semiconductor
processing chamber, such as, for example, temperature sensors on a
rotating support structure or surrounding ring inside a processing
chamber. The internal power source and/or the wireless
communication device can be used with other types of sensors
besides or in addition to the substrate detection system.
[0060] For example, as shown in FIG. 16, the internal power source
152 and/or the wireless communication device 154 may be used with a
temperature measurement system (e.g., a series of temperatures
sensors 160) or a gas composition detection sensor 162. In the
illustrated embodiment, the temperature sensors and gas sensors are
placed on a generally flat circular susceptor 164, which is
supported by a spider 166 within the sealed environment 153 of, for
example, a processing chamber. The spider 166 is mounted on a
tubular shaft 168 which may extends through the processing chamber.
Details of such an arrangement together with a drive mechanism can
be found in U.S. Pat. No. 4,821,674, which is incorporated herein
by reference. In the illustrated embodiment, the wireless
communication device 154 is placed on the spider. In a modified
arrangement, the wireless communication device can be powered by an
internal power source that is mounted, for example, on the spider
166.
[0061] Of course, the foregoing description is that of preferred
embodiments of the invention and various changes, modifications,
combinations and sub-combinations may be made without departing
from the spirit and scope of the invention, as defined by the
appended claims.
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