JP7664352B2 - Wafer Transfer Device - Google Patents

Description

The present invention relates to a wafer transport device.

Conventionally, in semiconductor manufacturing equipment, a configuration for transporting semiconductor wafers (hereinafter referred to as "wafers") between various processing steps is known (see, for example, Patent Document 1).

The plane processing device known from Patent Document 1 that grinds the back surface (one surface) of a wafer includes a chuck that holds the wafer by suction, a rough grinding wheel, a fine grinding wheel, and a polishing device. With this plane processing device, the wafer is processed in such a way that the front surface (other surface) of the wafer is held by suction with the chuck, the rough grinding wheel is pressed against the back surface of the wafer, and the chuck and the wheel are rotated to roughly grind the back surface. After the rough grinding is completed, the wafer is then fine ground by the fine grinding wheel. After the fine grinding is completed, the wafer is transported to a cleaning device and its back surface is cleaned. This completes the back surface grinding process of one wafer by the plane processing device.

In the above-mentioned flat processing device, the wafer after the backside grinding process is transferred to the next process, which is the cleaning process. That is, the wafer is moved from the first position where the backside grinding process is performed to the second position where the next cleaning process is performed. At this time, a method is known in which the wafer is transported using a suction holding means that suction-holds the wafer and a transport device that moves the suction holding means from the first position to the second position.

However, in the conventional wafer transfer device, the wafer is attracted to and held on the surface of the porous portion of the attracting and holding means, which causes the following problems (1) to (4).
(1) When the wafer is attracted and held, a strong stress is applied to the wafer, such as deformation of the wafer.
(2) There is a risk of scratching the front surface of the wafer by bringing the rough porous portion into contact with the rear surface of the wafer.
(3) When a wafer is processed, simple cleaning is performed, but sludge may not be washed away and may remain. If sludge remains, the sludge may be sucked into the porous part when the wafer is vacuum-adsorbed onto the porous part, causing clogging of the porous part or transferring of the sludge to the porous part.
(4) If sludge remains, the sludge is dried and fixed on the porous portion and the wafer by vacuum suction and air blow release (release air), respectively, making cleaning difficult.

Therefore, a non-contact wafer transport device is also known that cleans the surface of the wafer and the surface of the porous portion with liquid to remove sludge when transporting the wafer, keeps the surface of the wafer and the surface of the porous portion moist, and enables transport in a stable state (see, for example, Patent Document 2).

The wafer transport device known from Patent Document 2 is a wafer transport device that includes an adsorption holding means for adsorbing and holding a wafer, and a transport means for moving the adsorption holding means from a first position to a second position, and the adsorption holding means includes a non-contact pad connected to the transport means, and a negative pressure generating means for spraying liquid from the pad surface of the non-contact pad facing the wafer, forming a liquid film and a negative pressure area on the pad surface side of the non-contact pad, thereby holding the wafer on the pad surface side of the non-contact pad in a non-contact state.

In the wafer transport device known from Patent Document 2, when liquid is sprayed from the pad surface of the non-contact pad by a negative pressure generating means, a liquid film and a negative pressure area are formed on the pad surface side of the non-contact pad. Then, due to the negative pressure formed on the pad surface side of the non-contact pad, the non-contact pad adsorbs and holds the wafer in a non-contact state due to the Bernoulli effect of the thin liquid film formed between the wafer holding surface and the pad surface of the non-contact pad, and the wafer can be moved from the first position to the second position together with the non-contact pad. During this movement, liquid is constantly flowing between the non-contact pad and the wafer, and a thin liquid film continues to be formed by the liquid. Therefore, with this wafer device, the pad surface, which is the underside of the non-contact pad, and the holding surface, which is one side of the wafer, can be transported from the first position to the second position in a moist state.

Patent No. 4808278 JP 2017-92397 A

In a wafer transport device, it is necessary to detect whether a wafer is held on the pad surface and transport the wafer while it is securely held by suction on the pad surface. In a conventional method, a pressure sensor is provided on the pad surface side, and when the wafer is held by suction, the wafer is pressed against the pressure sensor, and the pressure applied from the wafer to the pressure sensor is detected to detect the presence of the wafer.

Another method is to use a photosensor with a light-emitting element and a light-receiving element arranged on either side of the wafer, and detect the presence of the wafer based on whether or not the wafer is between the light-emitting element and the light-receiving element.

However, in non-contact wafer transport devices, conventional wafer detection methods using pressure sensors do not create contact between the pressure sensor and the wafer, making detection using a pressure sensor impossible. On the other hand, wafer detection methods using photosensors can sometimes result in false detections due to a liquid film that forms between the light-emitting element and the light-receiving element.

Therefore, when transporting wafers using non-contact pads, a technical problem arises that must be solved in order to provide a wafer transport device that can reliably check the presence of wafers and transport wafers in a stable manner, and the present invention aims to solve this problem.

The present invention has been proposed to achieve the above-mentioned object, and the invention described in claim 1 provides a wafer transport device having a non-contact pad that forms a liquid film between a wafer after grinding and a pad surface, and adsorbs and holds the wafer via the liquid film, the non-contact pad having a liquid discharge port that discharges the liquid that forms the liquid film between the pad surface and the wafer, and a plurality of capacitive proximity sensors that detect the presence or absence of the liquid film between the pad surface and the wafer.

According to this configuration, when liquid is discharged from the liquid discharge port of the non-contact pad, a liquid film is formed between the pad surface of the non-contact pad and the wafer. Then, due to the Bernoulli effect of the liquid film formed between the pad surface of the non-contact pad and the wafer, the non-contact pad can adsorb and hold the wafer in a non-contact state and move it from the first position to the second position. During this movement, liquid is constantly flowing between the non-contact pad and the wafer, and a thin liquid film of the liquid continues to be formed on the wafer. Therefore,
(1) The wafer can be transported from the first position to the second position while the pad surface of the non-contact pad and the holding surface, which is one surface of the wafer, are kept moist.
(2) In addition, at the start of transport (when the substrate is held by the chuck) and during transport, the pad surface and the holding surface are simultaneously cleaned.
(3) By forming a thin liquid film between the pad surface and the holding surface, the wafer can be transported without damaging the holding surface.
(4) By forming a thin liquid film between the pad surface and the holding surface, the liquid film acts as a cushion and can suppress vibration of the wafer during transportation.

A proximity sensor is also provided to detect the presence or absence of a liquid film between the pad surface and the holding surface, and the presence or absence of a wafer is detected from the presence or absence of the liquid film, so that the presence of the wafer can be confirmed reliably and the wafer can be transported in a stable state. In other words, if there is no wafer, the liquid discharged into the liquid discharge port falls freely and does not form a liquid film, so the proximity sensor does not detect the liquid film and it is known that there is no wafer. Conversely, if there is a wafer, a liquid film is formed and the proximity sensor detects this liquid film, so the presence of the wafer is detected.

The invention described in claim 2 provides a wafer transport device in the configuration described in claim 1, in which the multiple proximity sensors are provided along the outer periphery of the wafer when the wafer is held by suction at approximately the center of the pad surface.

With this configuration, multiple proximity sensors are provided along the inner circumference of the underside of the non-contact pad while the wafer is held by suction at approximately the center of the pad surface. If the wafer shifts off the underside of the non-contact pad, the proximity sensor provided in the detached portion can detect that the wafer has strayed from the area.

The invention described in claim 3 provides a wafer transport device according to the configuration described in claim 1 or 2, in which the liquid discharge ports are provided in a plurality on the underside of the non-contact pad.

With this configuration, multiple liquid discharge ports are provided on the underside of the non-contact pad, dispersing the amount of liquid discharged onto the underside of the non-contact pad, and making the thickness of the liquid film formed between the underside of the non-contact pad and the wafer holding surface uniform. This distributes the force that holds the wafer by suction over the entire underside of the non-contact pad, allowing the wafer to be stably held by the liquid film.

The invention described in claim 4 provides a wafer transport device according to the configuration described in claim 1, 2, or 3, in which the non-contact pad has a plurality of positioning pins along the outer periphery of the wafer to prevent the wafer from protruding laterally from the pad surface when the wafer is held by suction at approximately the center of the pad surface.

With this configuration, multiple positioning pins that prevent the wafer from protruding laterally from the pad surface are provided along the outer periphery of the underside of the non-contact pad, so the positioning pins can prevent the wafer from shifting laterally from the pad surface.

According to the invention, when the wafer is transported, liquid is discharged from the liquid discharge port of the non-contact pad to form a liquid film between the non-contact pad and the wafer, and the wafer is attracted and held in a non-contact state by the Bernoulli effect of the liquid film, and a proximity sensor is provided on the non-contact pad to detect the presence or absence of a liquid film between the non-contact pad and the wafer, thereby detecting the presence or absence of the wafer.
(1) The presence of wafers can be reliably confirmed, and wafers can be transported in a stable state.
(2) Furthermore, the pad surface of the non-contact pad and the wafer holding surface can be transported from the first position to the second position in a moistened state without drying out.
(3) In addition, at the start of transfer and during transfer, the wafer holding surface and the pad surface of the non-contact pad can be simultaneously cleaned, making it possible to hold them in a sludge-free state.
(4) By forming a thin liquid film between the pad surface and the holding surface, the wafer can be transported without scratching the holding surface.
(5) By forming a thin liquid film between the pad surface of the non-contact pad and the wafer holding surface, the liquid film acts as a cushion and can suppress vibration of the wafer during transportation.

1 is an overall perspective view of a wafer transfer device shown as an example according to an embodiment of the present invention; 2 is a plan view of a non-contact pad in the wafer transfer device shown in FIG. 1 as viewed from the bottom side. FIG. 3 is a side view taken along the line AA in FIG. 2, showing a state in which the liquid has been discharged and the wafer is held by suction on the non-contact pad in a non-contact state. FIG. 3 is a cross-sectional view taken along line BB in FIG. 2, showing a state in which the liquid has been discharged and the wafer is held by suction on the non-contact pad in a non-contact state. 13 is a plan view showing a modified example of the non-contact pad in the wafer transfer device as viewed from the pad surface side. FIG.

To achieve the objective of providing a wafer transport device that can reliably check the presence of a wafer and transport the wafer in a stable state when transporting the wafer using a non-contact pad, the present invention provides a wafer transport device that has a non-contact pad that forms a liquid film between the wafer and the pad surface and adsorbs and holds the wafer via the liquid film, in which the non-contact pad is provided with a liquid discharge port that discharges the liquid that forms the liquid film between the pad surface and the wafer, and a capacitance-type proximity sensor that detects the presence or absence of the liquid film between the pad surface and the wafer.

An example of a wafer transfer device according to an embodiment of the present invention will be described in detail below with reference to the attached drawings. Note that in the following examples, when the number, numerical value, amount, range, etc. of components are mentioned, they are not limited to a specific number, and may be more or less than the specific number, unless otherwise specified or in principle clearly limited to a specific number.

In addition, when referring to the shape or positional relationship of components, etc., this includes things that are substantially similar or similar to that shape, etc., unless otherwise specified or considered in principle to be clearly different.

In addition, drawings may exaggerate characteristic parts to make the features easier to understand, and the dimensional ratios of components may not be the same as in reality. In addition, in cross-sectional views, hatching of some components may be omitted to make the cross-sectional structure of the components easier to understand.

In addition, in the following description, expressions indicating directions such as up/down and left/right are not absolute, but are appropriate when each part of the wafer polishing apparatus of the present invention is in the posture depicted, but if the posture changes, they should be interpreted differently depending on the change in posture. Also, the same symbols are used for the same elements throughout the description of the embodiments.

Figure 1 is an overall perspective view showing the main components of a wafer transport device 11 in a semiconductor manufacturing device 10 to which the present invention is applied. The wafer transport device 11 in Figure 1 is formed across the grinding section 12 and cleaning section 13 in the semiconductor manufacturing device 10. The grinding section 12, which is the first position, is provided with a grinding device 14 and a porous chuck 15, and the cleaning section 13, which is the second position, is provided with a cleaning device 16 and a porous chuck 17.

In the grinding section 12, a grinding wheel 18 that rotates horizontally is attached to the tip of the grinding device 14 that is positioned opposite the porous chuck 15. The porous chuck 15 of the grinding section 12 can be moved horizontally to a grinding position that corresponds vertically to the grinding wheel 18 of the grinding device 14, and to a transportable position that is not directly below the grinding device 14. Note that FIG. 1 shows the porous chuck 15 in a state where it has been moved to the transportable position.

The porous chuck 15 is composed of a ceramic porous portion 15a and a ceramic body 15b. Although not shown, the porous chuck 15 uses an air pipe provided in the center of the body 15b to draw a vacuum when chucking, chucking the wafer W onto the body 15b, and when releasing, release air is supplied to release the wafer W.

In the grinding section 12, a rotating grindstone 18 is pressed against the wafer W, which rotates together with the porous chuck 15, to grind the back surface of the wafer W.

The cleaning processing section 13 is provided with a cleaning device (detailed structure is omitted) 16 and a porous chuck 17 disposed within the cleaning device 16.

Like the porous chuck 15, the porous chuck 17 is composed of a ceramic porous portion 17a and a ceramic body 17b. Although not shown, like the porous chuck 15, the porous chuck 17 also has an air pipe provided in the center of the body 17b that draws a vacuum when chucking the wafer W onto the body 17b, and releases the wafer W by supplying release air when releasing it.

In this cleaning section 13, the back surface of the wafer W that has been subjected to grinding processing in the grinding section 12 and then transported to the cleaning device 16 and set on the body 17b of the porous chuck 17 in the cleaning device 16 can be cleaned.

The wafer transfer device 11 includes an adsorption/holding means 19 that adsorbs and holds the wafer W, and a transfer means 20 that reciprocates the adsorption/holding means 19 from a first position (grinding position) to a second position (grinding position).

As shown in FIG. 1, the conveying means 20 has an X-axis direction guide portion 20a that can move the suction holding means 19 back and forth in the X-axis direction (the horizontal direction connecting the first position and the second position), and a Y-axis direction guide portion 20b that can move the suction holding means 19 back and forth in the Y-axis direction (the up and down direction). The conveying means 20 operates in the Y-axis direction to move the suction holding means 19 up and down. The conveying means 20 operates in the X-axis direction to move the suction holding means 19 horizontally, so that the suction holding means 19 can be moved back and forth from the first position to the second position and from the second position to the first position.

The suction holding means 19 comprises a holding body part 19a connected to the Y-axis direction guide part 20b of the conveying means 20, and a non-contact pad 19b fixedly attached to the tip part (lower end part) of the holding body part 19a.

As shown in FIG. 4, a central through hole 21 is provided inside the holding body 19a, and a water supply pipe 22 is arranged inside the central through hole 21. The tip end (lower end) 22a of the water supply pipe 22 is connected to the non-contact pad 19b. Although not shown, the other end (base end) of the water supply pipe 22 is connected to a liquid storage tank (not shown) capable of supplying a liquid 23, such as water (pure water), at high pressure, so that the high-pressure liquid is supplied from the liquid storage tank.

As shown in Figures 2 to 4, the non-contact pad 19b has a roughly disk-shaped pad body 24. A water inlet 26 that leads to a water distribution passage 25 provided inside the pad body 24 is provided on the upper surface 24c of the pad body 24, and the tip 22a of the water supply pipe 22 is connected to the water inlet 26.

The pad surface 24a and a plurality of liquid discharge ports 27 are provided on the lower surface 24d of the pad main body 24. The plurality of liquid discharge ports 27 are provided within the area covered by the wafer W when the wafer W is held by suction at approximately the center of the pad surface 24a. More specifically, the periphery of the liquid discharge port 27 protrudes downward in a circular ring shape, and the pad surface 24a is provided with a flat lower surface (annular protruding lower surface) of the liquid discharge port 27. As shown in FIG. 2, the liquid discharge ports 27 provided on the pad surface 24a are composed of six outer peripheral discharge ports 27a formed at equal intervals of approximately 60° along the inner periphery of the outer periphery of the lower surface 24d of the pad main body 24 (the inner periphery of the area that holds the wafer W by suction), and three center side discharge ports 27b formed at equal intervals of approximately 120° along the inner periphery of the outer periphery, closer to the center than the outer peripheral discharge ports 27a. Therefore, nine pad surfaces 24a are provided on the underside of each liquid discharge port 27, the same number as the number of liquid discharge ports 27. The center discharge port 27b is disposed at a rotational angle of approximately 30° relative to the outer peripheral discharge port 27a. With this arrangement, the outer peripheral discharge port 27a, the center discharge port 27b, and the pad surface 24a are disposed on the pad main body 24 in a substantially even balance.

The outer periphery discharge port 27a and the center discharge port 27b are each connected to a water distribution channel 25 provided in the holding body 19a. When liquid 23 flows in from the water supply pipe 22 connected to the water inlet 26 through the water inlet 26, the water distribution channel 25 distributes the amount of the flowed-in liquid 23 approximately evenly to the outer periphery discharge port 27a and the center discharge port 27b, respectively, so that approximately equal amounts of liquid 23 can be discharged from the outer periphery discharge port 27a and the center discharge port 27b at each location.

Six positioning pins 28 are attached to the outer peripheral surface 24b of the pad body 24 along the outer periphery of the lower surface of the pad body 24 (the outer periphery of the area that holds the wafer W by suction), protruding downward from the nine pad surfaces 24a that define the wafer suction holding area. The positioning pins 28 abut against the outer peripheral surface of the wafer W to prevent it from popping out when the wafer W held by suction on the pad surface 24a tries to pop out by shifting laterally (horizontally) from the area that holds the wafer W by suction, and are provided at 60° intervals corresponding to the outer peripheral release port 27a.

The pad body 24 also has three sensor mounting holes 29 that penetrate vertically, spaced at 120° intervals along the inner circumference of the lower surface of the non-contact pad 19b and positioned between the outer periphery discharge ports 27a. The sensor mounting holes 29 are located along the outer periphery of the wafer W within the area where the wafer W is held by suction at approximately the center of the pad surface 24a. A proximity sensor 30 is attached to each sensor mounting hole 29.

The proximity sensor 30 is a capacitance type sensor and is attached in the sensor attachment hole 29 with the detection surface 30a facing downward. The proximity sensor 30 is a general-purpose capacitance type proximity sensor and detects the liquid film 23a of the liquid 23 formed on the underside of the pad main body 24 and the wafer W adsorbed and held on the pad surface 24a.

Next, an example of the transport operation of the wafer transport device 11 in the semiconductor manufacturing device 10 configured as above will be described, which transports the wafer W to the cleaning and processing section 13 at the second position after grinding processing at the grinding processing section 12 at the first position.

First, the porous chuck 15 holding the wafer W after grinding is moved to a transportable position away from the grinding device 14 as shown in FIG. 1.

Then, the suction holding means 19 is transported above the porous chuck 15, and the pad surface 24a of the non-contact pad 19b is positioned by the transport means 20 so that it is close to the back surface of the wafer W, i.e., the holding surface Wa, in a non-contact state. In this state, the suction chuck to the wafer W on the porous chuck 15 side is also removed.

Next, as shown in FIG. 4, liquid 23 is introduced into the pad body 24 from the water inlet 26 through the water supply pipe 22. When liquid 23 is introduced into the pad body 24, the introduced liquid 23 flows through the water distribution path 25 to the multiple liquid outlets 27 (multiple outer periphery outlets 27a and multiple center outlets 27b).

At each of the multiple liquid discharge ports 27 through which the liquid 23 flows, the liquid 23 is discharged in an approximately equal amount from each liquid discharge port 27, forming a flow of liquid 23 over the entire area between the pad surface 24a of the non-contact pad 19b and the holding surface Wa of the wafer W. This flow of liquid 23 then flows outward while forming a thin liquid film 23a between the pad surface 24a and the wafer W. In this embodiment, this flow of liquid 23 forms a negative pressure area over almost the entire pad surface 24a according to Bernoulli's principle, and this negative pressure causes the wafer W to be sucked and held on the pad surface 24a of the non-contact pad 19b via the liquid film 23a, thereby achieving suction and holding in a non-contact state.

In addition, a negative pressure area is formed over the entire pad surface 24a of the non-contact pad 19b, and the wafer W on the porous chuck 15 is attracted and held by the negative pressure in the negative pressure area against the pad surface 24a of the non-contact pad 19b as shown in Figures 3 and 4. While maintaining this state, the suction holding means 19 is moved upward by the transport means 20, and then moved to the second position, the cleaning processing section 13. Then, the wafer W that is attracted and held on the pad surface 24a of the non-contact pad 19b is positioned close to the porous chuck 17 of the cleaning processing section 13.

Then, the supply of liquid 23 from the water supply pipe 22 is cut off. When the supply of liquid 23 is cut off, the liquid film 23a and negative pressure generated between the pad surface 24a and the holding surface Wa also disappear, and the negative pressure on the pad surface 24a of the non-contact pad 19b is released. Then, the wafer W that was held in a non-contact state on the pad surface 24a of the non-contact pad 19b is dropped onto the porous chuck 17 of the cleaning processing section 13 and transferred onto the porous chuck 17. At this time, if negative pressure is generated on the porous chuck 17 side, the wafer W can be smoothly transferred from the pad surface 24a of the non-contact pad 19b to the porous chuck 17 side of the cleaning processing section 13.

When the pad surface 24a of the non-contact pad 19b is placed close to the holding surface Wa of the wafer W in a non-contact state and is adsorbed and held by the liquid film 23a, if the wafer W is present on the porous chuck 15, the liquid film 23a on the wafer W is detected by the proximity sensor 30 as the thin liquid film 23a formed between the pad surface 24a and the holding surface Wa flows over the wafer W. In addition, the detection of the liquid film 23a by the proximity sensor 30 detects that the wafer W is present on the porous chuck 15.

In contrast, when no wafer W is present on the porous chuck 15, the liquid 23 discharged from each water outlet 37 falls straight down, and no liquid film 23a is formed below the pad surface 24a, i.e., below the proximity sensor 30. In other words, since the proximity sensor 30 does not detect the liquid film 23a, it is possible to detect that no wafer W is present on the porous chuck 15.

Furthermore, if the position of the wafer W is significantly misaligned in the lateral direction (horizontal direction) with respect to the pad surface 24a, the liquid film 23a between the pad surface 24a and the holding surface Wa of the wafer W will not be formed uniformly at the three proximity sensors 30. As a result, the three proximity sensors 30 will not detect the liquid film 23a in the same way, and it can be detected that the wafer W is not set correctly on the porous chuck 15. Furthermore, the degree of misalignment when the wafer transport device 11 holds the wafer W can also be detected, making it possible to detect excessive lateral misalignment.

In addition, if the wafer W is about to jump out of the pad surface 24a due to a large lateral shift during transport, the peripheral surface of the wafer W comes into contact with the positioning pins 28, which prevent further lateral shift. This eliminates lateral shift during transport and ensures reliable transport.

In the above embodiment, three proximity sensors 30 are provided at equal intervals. However, if the proximity sensor 30 is not used to detect horizontal positional deviation of the wafer W, a structure with only one proximity sensor 30 may be used, as shown in FIG. 5.

In addition, the positioning pin 28 provided on the outer peripheral surface 24b of the pad body 24 is not necessarily required if the suction holding based on Bernoulli's principle is strong.

In addition, the liquid discharge port 27 is shown to protrude below the lower surface 24d of the pad main body 24, and the lower surface of the liquid discharge port 27 is shown to be the pad surface 24a. However, the liquid discharge port 27 may not protrude, but may be flush with the lower surface 24d of the pad main body 24, and the entire lower surface 24d of the pad main body 24 may be shown to be the pad surface 24a.

Therefore, in the wafer transport device 11 configured in this manner, a proximity sensor 30 is provided on the non-contact pad 19b, which detects the presence or absence of a liquid film 23a formed between the pad surface 24a and the holding surface Wa, and the presence or absence of the liquid film 23a is used to detect the presence of the wafer W. This makes it possible to reliably confirm the presence of the wafer W and transport the wafer W in a stable state.

During the transfer and movement of the wafer W, the liquid 23 is discharged from the liquid discharge port 27 onto the pad surface 24a of the non-contact pad 19b to form a liquid film 23a between the pad surface 24a of the non-contact pad 19b and the holding surface Wa of the wafer W, and the pad surface 24a of the non-contact pad 19b continues to hold the wafer W in a non-contact state due to the Bernoulli effect of the liquid film 23a. At the same time, a proximity sensor 30 is provided on the non-contact pad 19b to detect the presence or absence of the liquid film 23a formed between the pad surface 24a and the holding surface Wa, and the presence or absence of the wafer W is detected from the presence or absence of the liquid film 23a.
(1) It is possible to reliably check the presence of the wafer W and to transport the wafer W in a stable manner.
(2) In addition, the pad surface 24a of the non-contact pad 19b and the holding surface Wa of the wafer W can be transported from the first position to the second position while being kept moist, without drying out.
(3) At the start of and during transfer, the holding surface Wa of the wafer W and the pad surface 24a of the non-contact pad 19b are also cleaned at the same time, making it possible to hold the wafer W in a sludge-free state.
(4) By forming a thin liquid film 23a between the pad surface 24a and the holding surface Wa, the wafer W can be transferred without being scratched on the holding surface Wa.
(5) By forming a thin liquid film 23a between the pad surface 24a and the holding surface Wa, the liquid film 23a acts as a cushion and can suppress vibration of the wafer W during transfer.

The present invention can be modified in various ways without departing from the spirit of the invention, and it goes without saying that the present invention extends to such modifications.

10: Semiconductor manufacturing equipment 11: Wafer transport device 12: Grinding section 13: Cleaning section 14: Grinding device 15: Porous chuck 15a: Porous section 15b: Body 16: Cleaning device 17: Porous chuck 17a: Porous section 17b: Body 18: Grindstone 19: Suction holding means 19a: Holding body 19b: Non-contact pad 20: Transport means 20a: X-axis guide 20b: Y-axis guide 21: Central through hole 22: Water supply pipe 22a: Tip 23: Liquid 23a: Liquid film 24: Pad body 24a: Pad surface 24b: Outer periphery 24c: Upper surface 24d: Lower surface 25: Water supply path 26: Water inlet 27: Liquid outlet 27a: Outer periphery outlet 27b : Center side discharge port 28 : Positioning pin 29 : Sensor mounting hole 30 : Proximity sensor 30a : Detection surface W : Wafer Wa : Holding surface

Claims (4)

1. A wafer transport device having a non-contact pad that forms a liquid film between a wafer after grinding and a pad surface and adsorbs and holds the wafer via the liquid film,
The non-contact pad is
a liquid discharge port for discharging the liquid that forms the liquid film between the pad surface and the wafer;
a plurality of capacitance type proximity sensors for detecting the presence or absence of the liquid film between the pad surface and the wafer. The wafer transport device according to claim 1, characterized in that the plurality of proximity sensors are provided along the outer periphery of the wafer when the wafer is held by suction at approximately the center of the pad surface. The wafer transport device according to claim 1 or 2, characterized in that the liquid discharge ports are provided in a plurality on the underside of the non-contact pad. The wafer transport device according to claim 1, 2 or 3, characterized in that the non-contact pad has a plurality of positioning pins arranged along the outer periphery of the wafer to prevent the wafer from protruding laterally from the pad surface when the wafer is held by suction at approximately the center of the pad surface.