JP7374591B2 - Wafer presence detection device - Google Patents

Description

The present invention relates to a device for detecting the presence of a workpiece (e.g., a wafer, etc.), and particularly for detecting whether or not a wafer is placed on a tray in a wafer polishing device that performs CMP processing on a wafer. The present invention relates to a wafer presence detection device.

In the field of semiconductor manufacturing, wafer polishing apparatuses are known that polish the surfaces of semiconductor wafers (hereinafter simply referred to as "wafers") such as silicon wafers.

The polishing apparatus described in Patent Document 1 is a polishing apparatus to which chemical mechanical polishing, so-called CMP (Chemical Mechanical Polishing) technology is applied. In this polishing apparatus, a waiting unit relays the transfer of wafers between a load/unload section to which wafers taken out of a cassette are transported and a polishing head that polishes the wafers.

The waiting unit is a wafer mounting table with an upper and lower structure, with the upper stage being a load-only wafer mounting table (in-table) with a tray that transfers wafers before polishing to the polishing head, and the lower stage wafers after polishing. This is a wafer placement table (out table) exclusively for unloading and has a tray for receiving wafers from the polishing head.

In this polishing equipment, when the in-table tray moves to a predetermined position (loading position) where the wafer is transferred to the polishing head, the polishing head with the retainer attached descends, holds the wafer by suction on the retainer, and holds the wafer on the polishing surface plate. The wafer is then transported to the top and polished.

After polishing, the wafer is moved onto an out-table tray, and the processed wafer is transferred to the out-table tray. The out table is transported to a predetermined position together with the processed wafer, and then moved to an unload cassette by a transport robot. Thereafter, by repeating such operations, it is possible to polish a large number of wafers in succession.

By the way, in the method of transporting wafers using a waiting unit, in order to eliminate mistakes such as double feeding of wafers, the in-table is moved from the transport robot when there are no wafers in the in-table tray or the out-table tray. The out-table must receive the polished wafer from the polishing head. Therefore, a wafer presence detection device is provided in the in-table tray and in the out-table tray to detect whether or not there are wafers. The conventional wafer presence detection device uses an optical sensor to detect the presence of wafers.

As shown in FIG. 7, an optical sensor 101 in a conventional wafer presence detection device has a light projecting section 102 and a light receiving section 103. On the other hand, an in-table (or out-table) tray 104 on which the wafer W is placed is provided with an opening 105 that passes through it vertically. In addition, the optical sensor 101 has a light projector 102 disposed on the lower surface side (or upper surface side) of the tray 104 in correspondence with the opening 105 of the tray 104, and a light emitting section 102 on the upper surface side (or lower surface side) of the tray 104. It is provided so that the light receiving section 103 is arranged.

When the wafer W is placed on the in-table (or out-table) tray 104, the optical sensor 101 closes the opening 105 with the wafer W, and the light is blocked by the wafer W. Since the light does not reach the light receiving unit 103, it is recognized that the wafer W is on the tray 104. On the other hand, if the wafer W is not placed on the tray 104 on the in-table or out-table, the opening 105 will be in an open state, and the light from the light projecting section 102 will pass through the opening 105 and reach the light receiving section 103. It is recognized that there is no wafer W on the tray 104. That is, the presence of wafers W on the in-table or out-table tray 104 is detected depending on whether the light from the light projecting section 102 enters the light receiving section 103 or not.

Patent No. 3510177

However, in the conventional structure in which the presence of wafers W is detected using the optical sensor 101, if water droplets adhere to the optical sensor 101, the presence of wafers W may be incorrectly detected.

Furthermore, nowadays there are transparent wafers W etc. made of transparent glass, but in the case of transparent wafers W, the light from the light projecting section 102 passes through the wafer W and enters the light receiving section 103. There is also the problem that the optical sensor 101 cannot be used when handling transparent wafers W.

Therefore, a technical problem has arisen that must be solved in order to provide a wafer presence detection device that can reliably detect the presence of wafers, even transparent wafers, without being affected by water droplets. , the present invention aims to solve this problem.

The present invention has been proposed to achieve the above object, and the invention according to claim 1 is a wafer presence detection device that detects whether or not a wafer is placed on a tray. is provided on the back side of the tray in which an opening is formed extending from the front side on which the wafer is placed to the back side, and the ultrasonic wave is emitted toward the wafer on the tray and an ultrasonic sensor that receives the reflected ultrasonic waves; and an ultrasonic sensor that is provided below the opening and refracts and reflects the ultrasonic waves emitted from the detection surface of the ultrasonic sensor toward the opening. and an ultrasonic reflecting surface that refracts and reflects the ultrasonic waves reflected from the surface of the wafer toward the detection surface of the ultrasonic sensor, and is on an ultrasonic path connecting the opening and the ultrasonic sensor. A wafer presence detection device is provided, which includes an ultrasonic refraction means provided in a wafer.

According to this configuration, the ultrasonic sensor is incorporated with the ultrasonic transmitter and the receiver placed on one side of the tray and the distance in the height direction shortened. This makes it possible to make the device more compact and to downsize the entire device. Note that although the ultrasonic transmitter and the receiver are generally the same part, they may be independent parts.

In addition, since ultrasonic waves are emitted towards the wafer surface and the ultrasonic waves reflected from the wafer surface are received, ultrasonic waves can be transmitted even if the wafer is transparent, such as a transparent wafer made of transparent glass. It can be reflected. This makes it possible to reliably detect the presence of wafers and improve detection accuracy.

Additionally , when an ultrasonic sensor placed on the back side of the tray emits ultrasonic waves toward the opening of the tray, if a wafer is placed on the front side of the tray, it hits the back side of the wafer and is reflected back to the tray. The ultrasonic waves returning through the opening can be received by an ultrasonic sensor, and the presence of wafers can thereby be detected. That is, if there are no wafers on the tray surface side, no reflection of ultrasonic waves will be obtained, but if there are wafers, reflection of ultrasonic waves will be obtained. Utilizing this fact, the presence of wafers can be easily detected. Furthermore, by arranging the ultrasonic reflecting surface of the ultrasonic refraction means, the arrangement and length of the ultrasonic path of the ultrasonic sensor can be freely changed. As a result, the shortest detection distance of the ultrasonic sensor is relatively long, but the detection distance can be increased by using the ultrasonic refraction means, and the ultrasonic sensor can be set horizontally to reduce the distance in the height direction. This makes it possible to downsize the device.

In the invention according to claim 2, in the configuration according to claim 1, the ultrasonic sensor and the ultrasonic refraction means are arranged substantially parallel to the back surface of the tray, and the ultrasonic sensor detects the The surface is arranged substantially perpendicular to the back surface of the tray to provide a wafer presence sensing device.

The invention according to claim 3 is the configuration according to claim 1, in which the ultrasonic sensor is arranged on the back side of the tray from the ultrasonic refraction means, and the detection surface of the ultrasonic sensor is A wafer presence detection device is provided, which is provided to be inclined toward the ultrasonic refraction means.

The invention according to claim 4 provides a wafer presence detection device having the configuration according to claim 1 , which includes a blower that blows air onto the ultrasonic reflecting surface.

According to this configuration, when water droplets, dust, etc. adhere to the ultrasonic reflecting surface, the air blown out from the blower blows off the water droplets, dust, etc. on the ultrasonic reflecting surface, and keeps the ultrasonic reflecting surface always clean. The accuracy of detecting the presence of wafers can be maintained.

The invention according to claim 5 is the configuration according to claim 1, 2, 3, or 4, which includes a blower for blowing air onto the ultrasonic transmitting surface and the ultrasonic receiving surface of the ultrasonic sensor. Provides a detection device.

According to this configuration, when water droplets, dust, etc. adhere to the ultrasonic transmitting surface and the ultrasonic receiving surface of the ultrasonic sensor, the air blown from the blower removes the water droplets, dust, etc. on the ultrasonic reflecting surface. By blowing away the ultrasonic waves, the ultrasonic transmitting surface and the ultrasonic receiving surface are always kept clean, and the accuracy of detecting the presence of wafers can be maintained.

According to the invention, the ultrasonic transmitter and the receiver are arranged on one side of the tray, and the ultrasonic sensor is incorporated with the distance in the height direction shortened, thereby making it possible to make the device more compact. . This makes it possible to downsize the entire device.

In addition, since ultrasonic waves are emitted toward the wafer surface and the ultrasonic waves reflected from the wafer surface are received, even if the wafer is transparent, such as a transparent wafer made of transparent glass, It is possible to reliably detect the presence of goods. Thereby, detection accuracy can be improved.

FIG. 1 is a plan view schematically showing the overall structure of a wafer polishing apparatus using the wafer presence detection device of the present invention. It is a figure which shows typically the principal part structure of the waiting unit in the same wafer polishing apparatus as the above, (a) is a front view of a waiting unit, (b) is a top view of a waiting unit seen from the upper side. 1 is a vertical sectional side view schematically showing the configuration of main parts of a wafer presence detection device according to a first embodiment of the present invention. FIG. 2 is a longitudinal sectional side view schematically showing the configuration of main parts of a wafer presence detection device according to a second embodiment of the present invention. FIG. 7 is a vertical cross-sectional side view schematically showing the configuration of main parts of a wafer presence detection device according to a third embodiment of the present invention. FIG. 7 is a vertical sectional side view schematically showing the configuration of main parts of a wafer presence detection device according to a fourth embodiment of the present invention. FIG. 2 is a longitudinal sectional side view schematically showing the configuration of main parts of a conventional wafer presence detection device.

The present invention has been made to provide a wafer presence detection device that can reliably detect the presence of wafers even when the wafers are transparent without increasing the size of the device. A wafer presence detection device detects whether or not a wafer is placed on a wafer, the device comprising: transmitting ultrasonic waves toward the wafer on the tray and transmitting an ultrasonic wave toward the wafer on at least one side of the tray; This was realized by including an ultrasonic sensor that receives the reflected ultrasonic waves.

Examples according to embodiments of the present invention will be described in detail below based on the accompanying drawings. In addition, in each example below, when referring to the number, numerical value, amount, range, etc. of constituent elements, the specific number is used unless it is specifically specified or it is clearly limited to a specific number in principle. The number is not limited to , and may be more than or less than a certain number.

In addition, when referring to the shape or positional relationship of constituent elements, etc., unless it is specifically specified or it is clearly considered that it is not the case in principle, etc., we refer to things that are substantially similar to or similar to the shape, etc. include.

Further, in the drawings, characteristic parts may be enlarged or exaggerated in order to make the features easier to understand, and the dimensional ratios of the constituent elements are not necessarily the same as in reality. Further, in the cross-sectional views, hatching of some components may be omitted in order to make the cross-sectional structure of the components easier to understand.

In addition, in the following explanation, expressions indicating directions such as up and down and left and right are not absolute, but are appropriate when each part of the wafer presence detection device of the present invention is in the depicted orientation. , if the posture changes, the interpretation should be changed according to the change in posture. Further, the same elements are given the same reference numerals throughout the description of the embodiments.

FIG. 1 is a plan view schematically showing the overall configuration of a wafer polishing apparatus 10 using a wafer presence detection device according to the present invention. In FIG. 1, a wafer polishing apparatus 10 is a CMP apparatus, and polishes the surface of a wafer W to a flat surface.

The wafer polishing apparatus 10 includes a load cassette 11, a transfer robot 12, an aligner 13, a waiting unit 14, a polishing surface plate 15, and an unload cassette 16. The waiting unit 14 also includes an in-table 17, a polishing head 18, and an out-table 19.

The load cassette 11 is used to temporarily store wafers W before polishing.

The transfer robot 12 is for loading the wafer W, receives the wafer W before polishing from the load cassette 11, and transfers the wafer W to the aligner 13, the in-table 17, the polishing head 18, the polishing surface plate 15, and the out-table 19 in this order. The wafer W is then transported to an unload cassette 16 where the wafer W after polishing processing is temporarily stored.

The aligner 13 adjusts the orientation of the wafer W taken out from the load cassette 11 and before being transferred to the waiting unit 14.

The polishing surface plate 15 is formed into a disk shape, and a polishing pad (not shown) is attached to the upper surface of the polishing plate 15 so as to be replaceable. The polishing surface plate 15 rotates together with the polishing pad around its axis by driving the rotational drive mechanism. The polishing surface plate 15 polishes the surface of the wafer W, which is pressed together with the polishing head 18, to a flat surface using a polishing pad.

FIG. 2 is a diagram schematically showing the configuration of the waiting unit 14, in which (a) is a front view of the waiting unit 14, and (b) is a plan view of the waiting unit 14 seen from above. In FIG. 2, the waiting unit 14 is a wafer mounting table with a two-stage structure, upper and lower. The waiting unit 14 is provided with a wafer presence detection device 40 according to the present invention.

The wafer mounting table on the upper stage side of the waiting unit 14 is an in-table 17 that serves as a loading-only wafer mounting table that transfers the wafer W before polishing to the polishing head 18. On the other hand, the wafer mounting table on the lower stage side is an out table 19 serving as a wafer placement table exclusively for unloading, which receives the wafer W after polishing from the polishing head 18 . The in-table 17 and the out-table 19 are each provided with a tray 41 on which a wafer W is placed and held. The tray 41 provided on the in-table 17 moves together with the in-table 17, and the tray 41 provided on the out-table 19 moves together with the out-table 19.

The in-table 17 and out-table 19 in the weighting unit 14 are connected to rodless cylinders 21a and 21b via connecting members 20a and 20b, respectively. In the weighting unit 14, when the rodless cylinders 21a and 21b are driven, the inner table 17 and the outer table 19 can move in the direction of the arrow Y in FIG. 2(b).

The polishing head 18 is configured to be able to slide above the tray 41 of the in-table 17 and the tray 41 of the out-table 19, and also to be able to move up and down in the vertical direction Z. The polishing head 18 receives the wafer W from the tray 41 of the in-table 17, moves to the top of the polishing surface plate 15 after receiving it, and descends during polishing to attach the wafer W to the top surface of the polishing surface plate 15. Polishing is performed by pressing the wafer W against a polishing pad that is not polished. Note that during the polishing process, CPM slurry, which is a mixture of an abrasive and chemicals, is supplied onto the polishing pad from a nozzle (not shown).

Further, after the polishing process, the wafer W is moved onto the out table 19 and the processed wafer W is transferred onto the tray 41 of the out table 19. The out table 19 is transported to a predetermined position together with the processed wafer W, and then moved to the unload cassette 16 by the transport robot 12.

In this way, in the wafer polishing apparatus 10 in which the wafer W is transferred via the tray 41 of the in-table 17 and the tray 41 of the out-table 19, serious mistakes such as double feeding of wafers W are eliminated, and movement and processing are smooth. In order to perform the necessary operations, it is necessary to detect the state of the wafers W in the tray 41 of the in-table 17 and the state of the wafers W in the tray 41 of the out-table 19. need to be executed. Therefore, in the wafer polishing apparatus 10 of this embodiment, the wafer presence detection device 40 that detects the state of the wafers W in each tray 41 in the in-table 17 and out-table 19 is They are provided corresponding to each table 19.

The wafer presence detection device 40 according to the first embodiment in the wafer polishing apparatus 10 of the present embodiment includes a wafer presence detection device 40 provided in the in-table 17 and a wafer presence detection device 40 provided in the out-table 19. The structure is almost the same as that of the cargo presence detection device 40 shown in FIG. Therefore, in the following description, in order to simplify the description, the wafer presence detection device 40 on the out-table 19 side will be described as a representative. Therefore, it should be understood that the same wafer presence detection device 40 as the wafer presence detection device 40 provided in the in-table 17 on the out-table 19 side is provided on the in-table 17 side.

As shown in FIG. 3, the wafer presence detection device 40 according to the first embodiment has a wafer W placed thereon and a tray 41 covered with the wafer W, which is placed approximately at the center of the tray 41 and extends from the tray surface 41a to the tray back surface 41b. It has an opening 42 that extends through it. Further, in the wafer presence detection device 40, an ultrasonic sensor 43 is arranged on the tray back surface 41b side of the tray 41 at a position corresponding to the opening 42, with the detection surface 43a facing the opening 42.

The ultrasonic sensor 43 itself is a well-known sensor, and emits ultrasonic waves from the transmitting part of the sensing surface 43a, and receives the ultrasonic waves reflected from one surface of the wafer W at the receiving part of the sensing surface 43a. The receiving operation is performed alternately, and the presence of wafers W on the tray 41 is detected based on whether there is an ultrasonic wave reflected from one surface of the wafer W and returned to the detection surface 43a. Note that, depending on the ultrasonic sensor 43, the detection surface 43a may have a separate ultrasound transmitting surface for emitting ultrasound waves and a receiving ultrasound receiving surface for receiving reflected ultrasound waves.

That is, in the wafer presence detection device 40 of the first embodiment shown in FIG. When an ultrasonic wave is emitted from the transmitter of the sensing surface 43a, the ultrasonic wave passes through the opening 42 and hits one surface of the wafer W, and the hit ultrasonic wave is reflected by the one surface of the wafer W and is transmitted to the sensing surface 43a. The signal enters the receiving section and is received by the detection surface 43a within a predetermined time. By alternately transmitting and receiving the ultrasonic waves, it is possible to detect whether or not the wafer W is present on the tray 41. Furthermore, since the wafer W is detected by detecting ultrasonic waves reflected from one surface of the wafer W, even if the wafer W is a transparent wafer W made of transparent glass, for example, the tray surface The wafer W placed on the wafer 41a can be reliably detected.

On the other hand, when the wafer W is not placed on the tray 41 and the opening 42 is not covered with the wafer W, when an ultrasonic wave is emitted from the transmitting part of the detection surface 43a of the ultrasonic sensor 43, The ultrasound waves pass upward through the opening 42 and are not reflected. Further, even if the light is reflected by another member, it is incident on the receiving section of the detection surface 43a for a time different from the predetermined time, and it is possible to detect that the wafer W is not present on the tray 41.

Therefore, in the wafer presence detection device 40 shown in FIG. 3, the ultrasonic transmitter and the receiver are arranged on one surface (the back surface in this embodiment) of the tray 41 to shorten the distance L in the height direction. In this state, the ultrasonic sensor 43 can be incorporated. Thereby, the wafer presence detection device 40 can be made more compact, and the wafer polishing apparatus 10 as a whole can be made more compact.

In addition, since ultrasonic waves are emitted toward one surface of the wafer W and the ultrasonic waves reflected from the one surface of the wafer W are received, even if the wafer is a transparent wafer made of transparent glass, for example, The presence of wafers W can be reliably detected, and the detection accuracy is improved.

FIG. 4 shows a wafer presence detection device 40 according to a second embodiment. The wafer presence detection device 40 of the second embodiment is provided with a reflecting plate 44 as an ultrasonic refraction means having an ultrasonic reflecting surface 44a between an opening 42 of a tray 41 and an ultrasonic sensor 43. It is. Note that the reflection plate 44 is a member such as a metal plate or a plastic plate that reflects sound waves, and has an ultrasonic wave reflection surface 44a provided on its surface. The ultrasonic sensor 43 is disposed below the tray back surface 41b of the tray 41 with the detection surface 43a facing the reflection plate 44, and the ultrasonic sensor 43 is placed below the tray back surface 41b of the tray 41, and is Ultrasonic waves can be transmitted approximately parallel to the back surface 41b (in the horizontal direction).

The ultrasonic reflecting surface 44a of the reflecting plate 44 refracts and reflects the ultrasonic waves emitted in the horizontal direction from the transmitting part of the detection surface 43a of the ultrasonic sensor 43 at a substantially right angle toward the tray 41, and The reflected light from the ultrasonic sensor 43 can be refracted and reflected at a substantially right angle toward the detection surface 43a of the ultrasonic sensor 43, and can be returned toward the detection surface 43a.

That is, in the wafer presence detection device 40 of the second embodiment shown in FIG. When an ultrasonic wave is emitted from the transmitter of the detection surface 43a, the ultrasonic wave is directed toward the ultrasonic reflection surface 44a of the reflection plate 44. The ultrasonic waves directed toward the ultrasonic reflecting surface 44a are reflected by the ultrasonic reflecting surface 44a, pass through the opening 42, and impinge on one surface of the wafer W. The ultrasonic waves that hit one surface of the wafer W are reflected by one surface of the wafer W, pass through the ultrasonic reflection surface 44a of the reflection plate 44, enter the receiving section of the detection surface 43a, and are received within a predetermined time. Therefore, in this embodiment as well, the presence of the wafer W on the tray 41 can be detected by alternately transmitting and receiving the ultrasonic waves. In addition, since this detection of the wafer W detects the ultrasonic waves reflected from one surface of the wafer W, even if the wafer W is a transparent wafer made of transparent glass, for example, it can be reliably detected. .

On the other hand, when the wafer W is not placed on the tray 41 and the opening 42 is not covered with the wafer W, when an ultrasonic wave is emitted from the transmitting part of the detection surface 43a of the ultrasonic sensor 43, As in the case of the first embodiment, the ultrasonic waves pass upward through the opening 42 and are not reflected. Furthermore, even if the light is reflected by another member, it does not enter the receiving section of the detection surface 43a within a predetermined time, and it is possible to detect that no wafer W is present on the tray 41.

Therefore, in the wafer presence detection apparatus 40 shown in FIG. Since the ultrasonic sensor 43 can be incorporated in the shortened state, the wafer presence detection device 40 can be made more compact, and the entire wafer polishing device 10 can be made more compact. Moreover, by arranging the reflection plate 44 between the opening 42 and the detection surface 43a of the ultrasonic sensor 43, the ultrasonic sensor 43 can be placed close to the tray back surface 41b of the tray 41, and ultrasonic The distance L in the height direction between the formula sensor 43 and the tray 41 can be reduced, and further compactness can be achieved. Furthermore, although the shortest detection distance of the ultrasonic sensor 43 is as long as about 50 mm or more, a reflecting plate 44 is provided between the opening 42 and the ultrasonic sensor 43, and the ultrasonic waves are reflected by the reflecting surface 44a for detection. By increasing the distance, it becomes possible to easily incorporate the ultrasonic sensor 43.

Further, as in the case of the first embodiment, ultrasonic waves are emitted toward one surface of the wafer W, and the ultrasonic waves reflected from the one surface of the wafer W are received. Even if the wafer W is a transparent wafer, the presence of the wafer W can be reliably detected, and the accuracy of detection is improved.

FIG. 5 shows a wafer presence detection device 40 according to a third embodiment. The wafer presence detection device 40 of the third embodiment uses ultrasonic waves having an ultrasonic reflecting surface 44a between the opening 42 of the tray 41 and the ultrasonic sensor 43, as in the second embodiment. A reflecting plate 44 is provided as a refracting means. The ultrasonic sensor 43 is placed below the tray back surface 41b of the tray 41 with the detection surface 43a facing the reflection plate 44, and emits ultrasonic waves from the transmitting portion of the detection surface 43a of the ultrasonic sensor 43. This device is substantially the same as the wafer presence detection device 40 of the second embodiment in that it can receive reflected ultrasonic waves.

The difference between the wafer presence detection device 40 of the third embodiment and the wafer presence detection device 40 of the second embodiment is that in the case of the second embodiment, the detection surface 43a of the ultrasonic sensor 43 is In the case of the third embodiment, the detection surface 43a of the ultrasonic sensor 43 is disposed obliquely downward, whereas the ultrasonic sensor 43 is disposed substantially perpendicularly to the rear surface 41b of the tray.

That is, if water droplets are scattered and attached to the detection surface 43a of the ultrasonic sensor 43 during cleaning of the wafer W, the ultrasonic waves may be refracted by the water droplets and the detection performance may deteriorate. . However, when the sensing surface 43a of the ultrasonic sensor 43 is provided diagonally downward as in the third embodiment, it is possible to prevent water droplets from adhering to the sensing surface 43a and stabilize the detection accuracy. can be achieved.

FIG. 6 shows a wafer presence detection device 40 according to a fourth embodiment of the present invention. The wafer presence detection device 40 of the fourth embodiment uses ultrasonic waves between the opening 42 of the tray 41 and the ultrasonic sensor 43, as in the case of the wafer presence detection device 40 of the second embodiment. A reflection plate 44 as an ultrasonic refraction means having a reflection surface 44a is provided, and blowers 45a and 45b are provided for blowing wind onto the ultrasonic reflection surface 44a and the detection surface 43a of the ultrasonic sensor 43, respectively.

As in the fourth embodiment, in a structure in which a blower 45a blows wind onto the ultrasonic reflecting surface 44a and a blower 45b blows wind onto the detection surface 43a of the ultrasonic sensor 43, the ultrasonic reflecting surface 44a and When water droplets, dust, etc. adhere to the sensing surface 43a, the wind from the blowers 45a, 45b can blow away the water droplets, dust, etc. on the ultrasonic reflecting surface 44a and the sensing surface 43a, and make them clean. This makes it possible to stabilize the ultrasonic path and maintain stable detection accuracy for the presence of wafers.

Note that in the first, second, third, and fourth embodiments, the structure in which the ultrasonic sensor 43 is provided on the tray back surface 41b side of the tray 41 is disclosed; It may be a structure. Further, it may be provided on both the tray front surface 41a side and the tray back surface 41b of the tray 41.

Furthermore, in the case of the second, third, and fourth embodiments, depending on the structure of the tray 41, the recess or recess in which the reflection plate 44 provided with the ultrasonic reflection surface 44a and the ultrasonic sensor 43 are placed may be placed in the tray. If the structure is such that the reflection plate 44 and the ultrasonic sensor 43 are arranged in a recessed part or in the recess, a part of the height of the reflection plate 44 and the ultrasonic sensor 43 is set in a part of the tray 41. It is also possible to absorb it within the thickness dimension of .

Furthermore, although each of the above embodiments has been described with reference to the case where it is applied to the waiting unit 14 of the wafer polishing apparatus 10, it is not limited to the application to the waiting unit 14 of the wafer polishing apparatus 10. It can be applied within the device.

Further, the present invention can be modified in various ways without departing from the spirit of the invention, and it is natural that the present invention extends to such modifications.

10: Wafer polishing device 11: Load cassette 12: Transfer robot 13: Aligner 14: Waiting unit 15: Polishing surface plate 16: Unloading cassette 17: In table 18: Polishing head 19: Out table 20a: Connecting member 20b: Connecting member 21a: Rodless cylinder 21b: Rodless cylinder 40: Load detection device 41: Tray 41a: Tray surface 41b: Tray back surface 42: Opening 43: Ultrasonic sensor 43a: Detection surface 44: Reflector plate 44a: Ultrasonic reflection Surface 45a: Blower 45b: Blower L: Distance in height direction W: Wafer Y: Arrow Z: Vertical direction

Claims (5)

A wafer presence detection device that detects whether or not a wafer is placed on a tray,
Provided on the back side of the tray in which an opening is formed extending from the front side on which the wafer is placed to the back side, the ultrasonic wave is emitted toward the wafer on the tray and is reflected by the surface of the wafer. an ultrasonic sensor that receives the ultrasonic waves;
Provided below the opening, the ultrasonic sensor emitted from the detection surface of the ultrasonic sensor is refracted and reflected toward the opening, and the ultrasonic wave reflected on the surface of the wafer is converted into an ultrasonic wave. an ultrasonic refracting means provided on an ultrasonic path connecting the opening and the ultrasonic sensor;
A wafer presence detection device comprising: The ultrasonic sensor and the ultrasonic refraction means are arranged substantially parallel to the back surface of the tray,
The wafer presence detection device according to claim 1 , wherein the detection surface of the ultrasonic sensor is arranged substantially perpendicular to the back surface of the tray . The ultrasonic sensor is disposed closer to the back side of the tray than the ultrasonic refraction means,
2. The wafer presence detection device according to claim 1, wherein the detection surface of the ultrasonic sensor is inclined toward the ultrasonic refraction means. The wafer presence detection device according to claim 1 , further comprising a blower that blows air onto the ultrasonic reflecting surface. 5. The wafer presence detection device according to claim 1, further comprising a blower that blows air onto the ultrasonic transmitting surface and the ultrasonic receiving surface of the ultrasonic sensor.