JPH0754915Y2 - Clamper status detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is used, for example, in an ion implantation apparatus, in which a substrate is sandwiched between a base and a clamper provided on the base and capable of opening and closing. The present invention relates to a clamper state detecting device for a substrate holding device that holds the device.

[Conventional technology]

 An example of this type of substrate holding device is shown in FIG.

This substrate holding device 1 is used, for example, in a batch processing type ion implantation device, and holds a substrate (for example, a wafer) 6 at the peripheral portion of a wafer disk 2 constituting a base by sandwiching the substrate (for example, a wafer) 6 therebetween. A plurality of clampers 4 (only one is shown) are provided so that they can be opened and closed vertically.

More specifically, the clamper 4 includes a ring portion 4a that presses the peripheral edge of the substrate 6, an arm portion 4b that supports the ring portion 4a, and a shaft 4c that connects the two. The arm portion 4b is mounted on the wafer disk 2. It is supported by a fixed base 10 via a shaft 8 so as to be vertically openable and closable. A torsion coil spring 12 is provided around the shaft 8 so that the clamper 4 is constantly pressed against the wafer disk 2.

The wafer disk 2 is housed in a vacuum container (not shown) and is moved to a predetermined substrate attaching / detaching position when the substrate 6 is attached / detached. Then, when the clamper 4 is opened, the push-up rod 14 comes up from below the wafer disk 2 through a through hole (not shown; see the through hole 16 in FIG. 2) provided in the wafer disk 2, forcibly pushing up the arm portion 4b. Open. When the clamper 4 is closed, when the push-up rod 14 is lowered, the clamper 4 is naturally closed by the reaction force of the torsion coil spring 12.

[Problems to be solved by the device]

However, in the substrate holding device 1 as described above, if there is any abnormality in the clamper 4 during the operation of closing the clamper 4, the clamper 4 stops in a state where it is not completely closed. Since it cannot be performed directly (that is, conventionally, the state of the clamper 4 is indirectly detected only by the movement of the push-up rod 14), which causes an inconvenience in the next processing operation. For example, when processing the substrate 6, the wafer disk 2 is rotated at high speed,
At that time, the substrate 6 may pop out or the clamper 4 may hit another structure.

Therefore, the main object of the present invention is to provide a clamper state detecting device capable of directly detecting that the clamper as described above is completely closed.

[Means for Solving the Problems]

In order to achieve the above object, the clamper state detecting device of the present invention comprises a combination of a light emitter and a light receiver, and the light emitted from the light emitter passes just above the clamper in a completely closed state and the light receiver. A transmission type photoelectric switch arranged so as to enter, and a combination of a sender and a receiver, so that the receiver receives the light emitted from the projector and reflected by the clamper in the closed state or a state close to the closed state. And a reflection type photoelectric switch arranged.

[Action]

According to the above configuration, when the clamper is completely closed, the transmissive photoelectric switch is in a light receiving state because the light passes right above the clamper, and the reflective photoelectric switch also reflects the light at the clamper. It will be done and returned, so it will be in a bright state.

When the clamper is slightly open, the transmissive photoelectric switch is blocked because the light is blocked by the clamper, and the reflective photoelectric switch is bright depending on the state of the reflected light from the clamper at that time. There may be a dark state.

When the clamper is wide open, the transmissive photoelectric switch is in a light receiving state because its light passes under the clamper, and the reflective photoelectric switch is in a dark state because there is no light reflected from the clamper.

Therefore, by using both the signal from the transmission type photoelectric switch and the signal from the reflection type photoelectric switch, it is possible to directly detect that the clamper is completely closed.

〔Example〕

FIG. 1 is a plan view showing an example in which a clamper state detecting device according to an embodiment of the present invention is arranged near a substrate holding device. FIG. 2 is a sectional view generally taken along the line I-I in FIG. The same or corresponding parts as those in the example of FIG. 3 are designated by the same reference numerals, and the difference from them will be mainly described below.

In this embodiment, the light 21 emitted from the projector 20a passes directly above the clamper 4 which is completely closed, as shown in the figure, through a transmissive photoelectric switch 20 consisting of a combination of a projector 20a and a receiver 20b. Then, they are arranged so as to enter the light receiver 20b.

More specifically, the light 21 passes through the clamper 4 immediately above the tip of the arm 4b having a large displacement amount.

These light projectors 20a and 20b are fixed to, for example, a structure inside a vacuum container that houses the wafer disk 2.

On the other hand, in this example, a through hole 24 is provided in a lower portion of one tip of the arm 4b, which is a part of the wafer disk 2 and has a large displacement amount in the clamper 4 in the closed state, and further below the through hole 24. A reflective photoelectric switch 22 with a built-in transmitter and receiver is provided, and the light emitted from this reflective photoelectric switch 22 is provided.
23 is applied to the clamper 4 (more specifically, the arm portion 4b) in the closed state or a state close thereto through the through hole 24, and the light 23 reflected from the clamper 4 is received by the reflection type photoelectric switch 22 again. I have to.

This reflection type photoelectric switch 22 is also fixed to a structure in a vacuum container that houses the wafer disk 2, for example.

According to the above configuration, when the clamper 4 is completely closed, the transmissive photoelectric switch 20 is in a light receiving state because the light 21 thereof passes directly above the clamper 4, and the reflective photoelectric switch 22 also has the light receiving state. Since the light 23 is reflected by the clamper 4 and returned, it becomes a bright state.

When the clamper 4 is slightly open, the transmission type photoelectric switch 20 is in a light shielding state because the light 21 is blocked by the clamper 4, and the reflection type photoelectric switch 22 is set to reflect the reflected light 23 from the clamper 4 at that time. Depending on the state, there may be a bright state and a dark state. Since the detection accuracy of the transmissive photoelectric switch 20 is generally high, it can be detected if the clamper 4 is opened even slightly, whereas the detection accuracy of the reflective photoelectric switch 22 is generally high. This is because it is not so high, and when the clamper 4 is only slightly opened, it is not possible to know which detection state it is in. That is, in this embodiment, the reflective photoelectric switch
22 is used to roughly detect whether the clamper 4 is below or above.

When the clamper 4 is wide open, the light 21 of the transmissive photoelectric switch 20 passes under the clamper 4, so that the light is received, and the reflective photoelectric switch 22 loses the reflected light 23 from the clamper 4. So it becomes dark.

The above three states are summarized in Table 1. Here, it is assumed that the transmissive photoelectric switch 20 and the reflective photoelectric switch 22 are turned on when receiving light.

As can be seen from this table, the transmission type photoelectric switch 20 or the reflection type photoelectric switch 22 alone cannot accurately detect the completely closed state of the clamper 4, but the signals from both 20 and 22 are used in combination ( For example, by taking an AND condition of ON signals from both sides, it is possible to directly and accurately detect that the clamper 4 is completely closed.

The reflective photoelectric switch 22 may be arranged so as to detect the open / closed state of the clamper 4 from a direction other than the above, for example, from above or from the side.

Further, instead of the integrated reflection type photoelectric switch 22 as described above, a reflection type photoelectric switch having a light emitter and a light receiver may be used.

Further, the clamper state detecting device as described above can be applied to a substrate holding device provided with a platen for holding one substrate 6 as a base instead of the wafer disk 2.

[Effect of device]

As described above, according to the present invention, since both the transmission type photoelectric switch and the reflection type photoelectric switch are provided, it is possible to directly and accurately detect that the clamper of the substrate holding device is completely closed.

[Brief description of drawings]

FIG. 1 is a plan view showing an example in which a clamper state detecting device according to an embodiment of the present invention is arranged near a substrate holding device. FIG. 2 is a sectional view generally taken along the line I-I in FIG. FIG. 3 is a plan view partially showing an example of the substrate holding device. 1 ... Substrate holding device, 2 ... Wafer disk (base), 4 ... Clamper, 6 ... Substrate, 20 ... Transmissive photoelectric switch, 20a ... Emitter, 20b ... Photoreceiver, 21 ...
Light, 22 …… Reflective photoelectric switch, 23 …… Light.

Claims (1)

[Scope of utility model registration request] 1. A substrate holding device for holding a substrate by sandwiching it between a base and a clamper openably and closably mounted on the base, which comprises a combination of a light emitter and a light receiver, and is emitted from the light emitter. The transmission type photoelectric switch arranged so that the light passes through the clamper in the completely closed state and enters the light receiver, and a combination of the light emitter and the light receiver, which is emitted from the light emitter and is in the closed state. And a reflection type photoelectric switch arranged so that a light receiver receives the light reflected by the clamper in a state of being close to the clamper state detection device.