CENTERING DEVICE AND SUBSTRATE PROCESSING APPARATUS

A centering device has three or more contact members each having a contact surface capable of contacting an end face of a substrate supported by a substrate support. These contact members are arranged to surround the substrate support in a horizontal plane with the contact surfaces facing an end face of the substrate. These contact members move toward the substrate in the mutually different directions to sandwich the substrate. Each contact surface is finished such that a contactable region formed to intersect the horizontal plane has a linear shape or a curved shape having a center of curvature located on the substrate side and having the radius of curvature larger than the radius of the substrate and is longer than an arc formed by cutting out the circumference of the substrate by the cut.

CROSS REFERENCE TO RELATED APPLICATION

The disclosure of Japanese Patent Application No. 2022-119717 filed on Jul. 27, 2022 including specification, drawings and claims is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a centering technique for horizontally moving and positioning a substrate such that a center of the substrate is aligned with a center of a substrate support with the disk-like substrate provided with a cut such as a notch in a peripheral edge part placed in a horizontal posture on the upper surface of the substrate support and a substrate processing apparatus for processing a substrate using the centering technique. This process includes a bevel etching process.

2. Description of the Related Art

In a known substrate processing apparatus, a chemical liquid process or a cleaning process is performed by supplying a processing liquid to a peripheral edge part of a substrate such as a semiconductor wafer while rotating the substrate. In an apparatus described in Japanese Patent Application Laid-Open No. 2019-149423, for example, a substrate is held under suction while being supported from below by a spin chuck (corresponding to an example of a “substrate support” of the present invention). In this case, misalignment between the center of the spin chuck and the center of the substrate decreases processing quality. In response to this, the above-described apparatus performs what is called a centering operation of reducing the amount of decentering of the substrate from the spin chuck before implementation of the process on the substrate.

SUMMARY OF INVENTION

The above-described conventional apparatus performs the centering operation in two stages. First, the amount of decentering i.e. eccentricity of the substrate from the spin chuck is measured. Next, the substrate on the spin chuck is pushed horizontally with a pusher to move the center of the substrate toward the center (rotary axis) of the spin chuck. Hence, room for improvement is left in terms of throughput.

Accordingly, a technique for performing the centering process without measuring the eccentricity amount is being studied. More particularly, three or more contact members are provided to surround the spin chuck in a horizontal plane. The contact members sandwich the substrate by moving toward an end face of the substrate in mutually different directions with the substrate placed on the spin chuck. In this way, the center of the disk-like substrate placed on the upper surface of the spin chuck can be aligned with the center of the spin chuck only by movements of the contact members.

However, if the substrate is provided with the cut such as a notch, centering accuracy is different depending on the configurations of the contact members as described in detail later with reference toFIG.4. Accordingly, in the centering device using three or more contact members, the configurations of the contact members need to be devised to enhance centering accuracy. However, this point has not been sufficiently studied.

This invention was developed in view of the above problem and aims to enhance centering accuracy in a centering device using three or more contact members provided to surround a substrate support having a disk-like substrate having a cut in a peripheral edge part placed thereon in a horizontal plane and a substrate processing apparatus using the centering device.

A first aspect of the invention is a centering device for horizontally moving and positioning a substrate such that a center of the substrate is aligned with a center of a substrate support with the disk-like substrate provided with a cut in a peripheral edge part placed in a horizontal posture on an upper surface of the substrate support. The device comprises: three or more contact members each having a contact surface capable of contacting an end face of the substrate, the three or more contact members being arranged to surround the substrate support in a horizontal plane in such a posture that the contact surfaces face the end face of the substrate; a moving mechanism configured to move the contact members toward the substrate in mutually different directions; and a controller configured to control the moving mechanism to sandwich the substrate by moving the contact members toward the substrate. Each contact surface is finished such that a contactable region formed to intersect the horizontal plane has a linear shape or a curved shape having a center of curvature on the substrate side and having a radius of curvature larger than a radius of the substrate and is longer than an arc formed by cutting out a circumference of the substrate by the cut.

A second aspect of the invention is a substrate processing apparatus. The apparatus comprises: a substrate support having an upper surface configured to support a disk-like substrate provided with a cut in a peripheral edge part in a horizontal posture; the centering device; a suction unit configured to suck and hold the substrate on the substrate support by exhausting air between the substrate positioned by the centering device and the substrate support; a rotation driver configured to rotate the substrate support sucking and holding the substrate about a center of the substrate support; and a processing liquid supply mechanism configured to supply a processing liquid to the peripheral edge part of the substrate rotated about the center of the substrate support integrally with the substrate support.

In the invention thus configured, three or more contact members each having the contact surface capable of contacting the end face of the substrate are provided. These contact members are arranged to surround the substrate support in the horizontal plane with the contact surfaces facing the end face of the substrate. These contact members move toward the substrate in the mutually different directions to sandwich the substrate. At this time, if the contact surface is facing the cut of the substrate, there is an influence of the cut. However, in the invention, the contact surface is finished such that the contactable region formed to intersect the horizontal plane has the linear shape or the curved shape having the center of curvature located on the substrate side and having the radius of curvature larger than the radius of the substrate and is longer than the arc formed by cutting out the circumference of the substrate by the cut. This can prevent a part of the contact member from entering the cut, with the result that the influence of the cut on centering accuracy is suppressed.

According to the invention, centering accuracy can be enhanced.

All of a plurality of constituent elements of each aspect of the invention described above are not essential and some of the plurality of constituent elements can be appropriately changed, deleted, replaced by other new constituent elements or have limited contents partially deleted in order to solve some or all of the aforementioned problems or to achieve some or all of effects described in this specification. Further, some or all of technical features included in one aspect of the invention described above can be combined with some or all of technical features included in another aspect of the invention described above to obtain one independent form of the invention in order to solve some or all of the aforementioned problems or to achieve some or all of the effects described in this specification.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG.1is a drawing showing a substrate processing system equipped with an embodiment of a substrate processing apparatus according to the invention. The substrate processing apparatus100includes a substrate processing station110for processing the substrate S and an indexer station120coupled to this substrate processing station110. The indexer station120includes a container holder121capable of holding a plurality of containers C for housing the substrates W (FOUPs (Front Opening Unified Pods), SMIF (Standard Mechanical Interface) pods, OCs (Open Cassettes) for housing a plurality of the substrates W in a sealed state), and an indexer robot122for taking out an unprocessed substrate S from the container C by accessing the container C held by the container holder121and housing a processed substrate S in the container C. A plurality of the substrates W are housed substantially in a horizontal posture in each container C.

The indexer robot122includes a base122afixed to an apparatus housing, an articulated arm122bprovided rotatably about a vertical axis with respect to the base122a, and a hand122cmounted on the tip of the articulated arm122b. The hand122cis structured such that the substrate S can be placed and held on the upper surface thereof. Such an indexer robot including the articulated arm and the hand for holding the substrate is not described in detail since being known.

The substrate processing station110includes a substrate conveyor robot111arranged substantially in a center in a plan view and a plurality of processing units1arranged to surround this substrate conveyor robot11. Specifically, the plurality of (eight in this example) processing units1are arranged to face a space where the substrate conveyor robot111is arranged. The substrate conveyor robot111randomly accesses these processing units1and transfers the substrates W. On the other hand, each processing unit1performs a predetermined processing to the substrate S. In this embodiment, these processing units1have the same function. Thus, a plurality of the substrates W can be processed in parallel. In the embodiment, one of the processing units1corresponds to the substrate processing apparatus10according to the invention.

FIG.2briefly shows a configuration in one embodiment of the substrate processing apparatus.FIG.3is a perspective view showing the configurations of a substrate holder and a centering mechanism of the substrate processing apparatus.FIG.4is a diagram schematically showing the configuration of a contact member that can be employed in the centering mechanism and the relationship with the notch of the substrate.FIG.5is a diagram schematically showing the operation of the centering mechanism.FIG.6is a diagram schematically showing the positional relationship between the contact member and the center of the spin base before and after the minute movement. The substrate processing apparatus10is an apparatus that performs a bevel etching process as an example of a “process” of the present invention, and supplies a processing liquid to a peripheral edge part of an upper surface of the substrate S in a processing chamber. For this purpose, the substrate processing apparatus10includes a substrate holder2, a centering mechanism3forming a principal structure of a centering device according to the present invention, and a processing liquid supply mechanism4. Operations of these structures are controlled by a control unit9responsible for control over the apparatus entirely.

The substrate holder2includes a spin base21that is a member of a smaller circular plate shape than the substrate S. The spin base21is supported on a rotary support shaft22extending downward from a central part of a lower surface of the spin base21in such a manner as to locate an upper surface211of the spin base21horizontally. The rotary support shaft22is rotatably supported by a rotary driver23. The rotary driver23includes a built-in rotary motor231. The rotary motor231rotates in response to a control command from the control unit9. In response to receipt of resultant rotary driving force, the spin base21rotates about a vertical axis AX (alternate long and short dashed lines) extending in a vertical direction while passing through a center21C of the spin base21. InFIG.2, a top-bottom direction corresponds to the vertical direction. A plane perpendicular to the plane of paper ofFIG.2is a horizontal plane. To clearly show a relationship in terms of direction, a coordinate system defining a Z axis as the vertical direction and an XY plane as the horizontal plane is given inFIG.2and its subsequent drawings, if appropriate.

The upper surface211of the spin base21has a dimension by which the substrate S is supportable to allow the substrate S to be placed on the upper surface211of the spin base21. Although not shown in the drawings, the upper surface211is provided with a plurality of suction holes or suction grooves, for example. Such suction holes or grooves are connected to a suction pump24through a suction pipe241. In response to a control command from the control unit9, the suction pump24operates to apply suction power from the suction pump24to the spin base21. As a result, air is exhausted from between the upper surface211of the spin base21and a lower surface of the substrate S, thereby holding the substrate S under suction on the spin base21. Together with the rotation of the spin base21, the substrate S held under suction in this way rotates about the vertical axis AX. Hence, the occurrence of misalignment between a center SC of the substrate S and the center21C of the spin base21, namely, decentering of the substrate S reduces the quality of the bevel etching process.

In response to this, the centering mechanism3is provided in the present embodiment. The centering mechanism3performs a centering operation while suction using the suction pump24is stopped (namely, while the substrate S is horizontally movable on the upper surface211of the spin base21). As a result of implementation of the centering operation, the above-described decentering is eliminated to make alignment between the center SC of the substrate S and the center21C of the spin base21. The configuration and operation of the centering mechanism3will be described later in detail.

The processing liquid supply mechanism4is provided to perform the bevel etching process on the substrate S after implementation of the centering operation on the substrate S. The processing liquid supply mechanism4includes a processing liquid nozzle41, a nozzle mover42that moves the processing liquid nozzle41, and a processing liquid supplier43that supplies a processing liquid to the processing liquid nozzle41. The nozzle mover42moves the processing liquid nozzle41between a retreat position to which the processing liquid nozzle41retreats laterally from a position above the substrate S as indicated by solid lines inFIG.2and a processing position above a peripheral edge part of the substrate S as indicated by dotted lines inFIG.2.

The processing liquid nozzle41is connected to the processing liquid supplier43. When a suitable processing liquid is supplied from the processing liquid supplier43to the processing liquid nozzle41located at the processing position, the processing liquid is ejected from the processing liquid nozzle41onto a peripheral edge part of the rotating substrate S. By doing so, the bevel etching process with the processing liquid is performed on the entire peripheral edge part of the substrate S.

Although not shown inFIG.2, a splash guard is provided in such a manner as to surround the substrate holder2from the side. The splash guard collects droplets of a processing liquid blown off from the substrate S during implementation of the bevel etching process to effectively prevent the collected droplets from flying around the apparatus.

The configuration of the centering mechanism3will be described next by referring toFIGS.2to6. The centering mechanism3has the function of determining the position of the substrate S by moving the substrate S horizontally on the upper surface211of the spin base21in such a manner as to align the center SC of the substrate S placed on the upper surface211of the spin base21with the center21C of the spin base21. As shown inFIG.3, as viewed in the X direction, the centering mechanism3includes a contact member31arranged closer to an X2direction (right-hand direction inFIG.3) and a contact member32and a contact member33arranged closer to an X1direction (left-hand direction inFIG.3) with respect to the center21C of the spin base21. The centering mechanism3further includes a moving mechanism34for moving the contact members31to33in a horizontal direction.

The moving mechanism34includes a single mover35for moving the contact member31, and a multi-mover36for moving the contact members32and33collectively. The single mover35is arranged closer to the X2direction and the multi-mover36is arranged closer to the X1direction with respect to the center21C of the spin base21.

The single mover35includes a fixed base351, a rotary motor352, a power transmitter353, and a slider354. The rotary motor352is mounted on the fixed base351, and the power transmitter353and the slider354are stacked in this order over the fixed base351. The rotary motor352is a driving source for moving the contact member31in the X direction. When the rotary motor352operates in response to a control command from the control unit9, a rotary shaft (not shown in the drawings) rotates. This rotary shaft extends from the top of the fixed base351to the power transmitter353and rotary driving force generated by the rotary motor352is transmitted to the power transmitter353. Using a rack-and-pinion structure, for example, the power transmitter353converts rotary motion responsive to the rotary driving force to liner motion in the X direction, and transmits the linear motion to the slider354. This makes the slider354move back and forth in the X direction by a distance responsive to the amount of the rotation. As a result, in response to the movement of the slider354, the contact member31mounted on the top of the slider354is moved in the X direction.

The multi-mover36has a configuration basically the same as that of the single mover35except that a slider364has a partially different structure. Specifically, the multi-mover36applies rotary driving force generated by a rotary motor362mounted on a fixed base361to the slider364using a power transmitter363, thereby moving the slider364in the X direction. The slider364has a top including two arms364aand364bextending in the X2direction and separated from each other in a Y direction. The top of the slider364has a substantially C-shape in a plan view from vertically above. The contact members32and33are mounted on end portions closer to the X2direction of the arms364aand364brespectively. Thus, when the rotary motor362operates in response to a control command from the control unit9, the slider364moves back and forth in the X direction by a distance responsive to the amount of the rotation of the rotary motor362, like in the single mover35. As a result, in response to the movement of the slider364, the contact members32and33mounted on the slider364are moved in the X direction.

The contact members31to33have contact surfaces311to331capable of contacting the end face Se of the substrate S, respectively. With these contact surfaces311to331directed toward the end face Se of the substrate S, the contact members31to33are arranged so as to surround the substrate holder2in the XY plane (horizontal plane). The contact surfaces311to331have a planar shape, and their surface normals face the vertical axis AX. For example, as shown in section (a) ofFIG.4, on the contact surface321, a linear region322that intersects a virtual horizontal plane including the substrate S placed on the upper surface of the substrate holder2corresponds to the “contactable region” of the present invention. Its length L is longer than the length Ln of the arc along which the circumference of the substrate S is cut off by the notch NT. Therefore, when the contact member32is moved toward the end face Se of the substrate S during centering, it contacts the end face Se of the substrate S at one or two points in the linear region322. That is, as shown inFIG.4, when the substrate S is placed on the upper surface of the spin base21with the notch NT facing the contact surface321, the two contact points CP1and CP2on the linear region322contact on the end face Se of the substrate S. On the other hand, in other areas, one contact point on the linear region322contacts the end face Se of the substrate S. The same applies to the contact surfaces311and331as well. The reason why the contact members31to33are configured as described above will be described later in detail with reference toFIG.4.

When the contact member31is moved in the X1direction by the single mover35, a contact surface311of the contact member31goes toward the center21C of the spin base21to contact on the end face Se of the substrate S. As described above, in the present embodiment, a D1direction in which the contact member31moves for abutting on the substrate S is the X1direction, and this direction corresponds to a “first horizontal direction” of the present invention. After making the abutting contact, the contact member31moves further in the D1direction, thereby moving the substrate S horizontally on the upper surface211of the spin base21in the X1direction while pressing the substrate S in the X1direction. In the present embodiment, to facilitate understanding of the substance of the invention, a virtual line VL extended in the X1direction from the center21C of the spin base21is additionally illustrated inFIGS.3,5and6. This line corresponds to a “virtual line” of the present invention. The configuration of the centering mechanism3will be described continuously using the virtual line VL in appropriate cases.

A configuration in which the contact members32and33are moved by the multi-mover36partially differs from that of the contact member31. The reason for this is that the contact members32and33are arranged line-symmetrically to each other with respect to the virtual line VL in the horizontal plane and are moved in the X direction while being kept in this arrangement state. More specifically, as shown in a section (a) ofFIG.5, the contact member32is arranged at a position deviating from the virtual line VL by a predetermined distance W (shorter than a radius rs of the substrate S) to be closer to a Y2direction. Meanwhile, the contact member33is arranged at a position deviating by the same distance W as the contact member32from the virtual line VL to be closer to the opposite side of the contact member32with respect to the virtual line VL, specifically, to be closer to a Y1direction. Thus, when the contact members32and33are moved in the X2direction by the multi-mover36, a contact surface321of the contact member32contacts on the end face at a position closer to the Y2direction than the virtual line VL. Furthermore, a contact surface331of the contact member33contacts on the end face at a position closer to the Y1direction than the virtual line VL. As described above, in the present embodiment, a D2direction in which the contact member32moves for abutting on the substrate S is the X2direction, and this direction corresponds to a “second horizontal direction” of the present invention. A D3direction in which the contact member33moves for abutting on the substrate S is also the X2direction, and this direction corresponds to a “third horizontal direction” of the present invention. Thus, in order to move the contact surfaces311,321, and331while distances from the center21C of the spin base21to the contact surfaces311,321, and331are kept equally, a movement amount per unit time is required to differ between the contact member31and the contact members32,33. This will be described in detail by referring toFIGS.5and6, and the centering operation using the above-described configuration of movement will also be described.

To place the substrate S on the upper surface211of the spin base21, the contact surfaces311,321and331are desirably positioned at reference positions at least in consideration of a maximum value of an outer diameter tolerance of the substrate S. For example, in the substrate S having a diameter of 300 mm, the outer diameter tolerance is 0.2 mm. Accordingly, the contact surfaces311,321and331need to be separated from the center21C of the spin base21by a distance of 150.1 mm or more. This distance is referred to as a “reference distance r0” in this embodiment and, as shown in field (a) ofFIG.5, a circle (one-dot chain line) having a radius centered on the center21C of the spin base21and equal to the reference distance r0is a reference circle.

Next, a case is studied where the contact surfaces311,321and331are moved toward the substrate S after the contact members31to33are so positioned that the contact surfaces311,321and331are located on the reference circle. In this case, the position of the contact member31for positioning the contact surface311on the reference circle corresponds to a “first reference position” of the invention, the position of the contact member32for positioning the contact surface321on the reference circle corresponds to a “second reference position” of the invention, and the position of the contact member33for positioning the contact surface331on the reference circle corresponds to a “third reference position” of the invention.

Here, a case is studied next, where the contact members31to33are located at the first reference position, the second reference position, and the third reference position respectively, the contact member31makes a tiny movement by a first movement amount Δd1in the D1direction (X1direction) toward the substrate S. If each of the contact members32and33makes a tiny movement by the same distance in the D2direction (X2direction) in response to the movement of the contact member31, the contact surfaces311,321, and331are separated by nonuniform distances from the center21C of the spin base21. Hence, repeating the tiny movements of the contact members31to33while keeping a uniform movement amount per unit time results in the failure to align the center SC of the substrate S with the center21C of the spin base21.

In contrast, as shown in field (b) ofFIG.5andFIG.6, the contact surfaces311,321and331can be moved while keeping the distances from the center21C of the spin base21to the respective contact surfaces311,321and331equal by finely moving the contact member32in the D2direction by a second movement amount Δd2and finely moving the contact member33in the D3direction by a third movement amount Δd3to correspond to a fine movement of the contact member31in the D1direction by a first movement amount Δd1.

FIG.6is a diagram schematically showing positional relationships between the contact member32and the center21C of the spin base21before and after the fine movement.FIG.6shows a positional relationship between a circle centered on the center21C of the spin base21and having a radius r1and the contact member32and a positional relationship between a circle centered on the center21C of the spin base21and having a radius r2and the contact member32. InFIG.6, the contact member32before the fine movement of the contact member32in the D2direction by the second movement amount Δd2is shown by a solid line and the contact member32after the fine movement is shown by a two-dot chain line.FIG.6shows a contact point324between the circle centered on the center21C of the spin base21and having the radius r1and the contact member32and a contact point325between the circle centered on the center21C of the spin base21and having the radius r2and the contact member32.

As shown inFIG.6, the contact points324and325are at different positions on the contact member32. On the other hand, a straight line connecting the center21C of the spin base21and the contact point324and a straight line connecting the center21C of the spin base21and the contact point325overlap. Further, an angle between the straight line connecting the center21C of the spin base21and the contact point324and a virtual line VL and an angle between the straight line connecting the center21C of the spin base21and the contact point325and the virtual line VL are equal.

Thus, a fine moving distance Δd2(corresponding to a “second movement amount” of the invention) of the contact member32and a fine moving distance Δd3(corresponding to a “third movement amount” of the invention) of the contact member33can be set as follows:Δd2=Δd3=(r1−r2)/cosθ=Δd1/cosθ,r1=r0, andr2=r1−Δd1,
where:r1: distance from the center21C to the contact surface321before the fine movement,θ: angle between the straight lines connecting the center21C of the spin base21and the contact points324,325and the virtual line,r2: distance from the center21C to the contact surface321after the fine movement, andW: separation distance of the contact member32from the virtual line VL.
In this case, even after the fine movement, the distances from the center21C of the spin base21to the contact surfaces311,321and331are equal. By repeating such fine movements, the contact members31to33approach the substrate S while keeping the distances from the center21C of the spin base21to the contact surfaces311,321and331equal. Then, for example, if there is a deviation as shown inFIG.5, the contact member31first contacts the substrate S and moves the substrate S in the D1direction while the above fine movements are repeated (see field (c) ofFIG.5). Subsequent to that, the contact member32contacts the substrate S pushed by the contact member31and horizontally moves the substrate S. Then, if the distances from the center21C of the spin base21to the contact surfaces311,321and331become the radius of the substrate S as shown in field (d) ofFIG.5, the last contact member33also contacts the substrate S. In this way, the substrate S is sandwiched by the contact members31to33to stop a movement thereof, and the center SC of the substrate S is aligned with the center21C of the spin base21. In this way, the centering process of the substrate S can be performed.

In the present embodiment including the centering mechanism3, the control unit9controls each part of the substrate processing apparatus10to perform the centering operation described above and the subsequent bevel etching process. The control unit9includes an arithmetic processor91composed of a computer with a central processing unit (CPU), a random access memory (RAM), etc., a storage92such as a hard disk drive, and a motor controller93.

The arithmetic processor91reads a centering program and a bevel etching program as appropriate stored in advance in the storage92, develops the program in the RAM (not shown in the drawings), and performs the centering operation and the bevel etching process shown inFIG.5. In particular, in performing the centering operation, the arithmetic processor91calculates the first movement amount Δd1to the third movement amount Δd3, and controls the rotary motors352and362of the moving mechanism34through the motor controller93on the basis of the calculated movement amounts Δd1to Δd3. Furthermore, the arithmetic processor91calculates a load torque at the single mover35on the basis of a motor current value applied to the rotary motor352and calculates a load torque at the multi-mover36on the basis of a motor current value applied to the rotary motor362. In response to change in a distance from the center21C of the spin base21to each of the contact surfaces311,321, and331(a distance from the base center to the contact surface) occurring while the tiny movements are repeated, the load torque varies in a manner shown inFIG.7, for example. As shown inFIG.7, at a time when this distance conforms to the radius rs of the substrate S, specifically, when the substrate S is nipped with the contact members31to33, the load torques increase steeply at the single mover35and the multi-mover36nearly simultaneously. At a time when the load torque exceeds a threshold, the arithmetic processor91determines that the centering operation is completed and stops the movements of the contact members31to33. In the present embodiment, variation in the load torque at each of the motors352and362is monitored. Alternatively, only one of the motors may be monitored to determine timing of stopping movements of the contact members31to33. Additionally, the load torque may certainly be calculated on the basis of an element other than the motor current value.

As described above, in the present embodiment, the contact members31to33make the tiny movements repeatedly to get closer to the substrate S gradually while distances from the center21C of the spin base21to the contact surfaces311,321, and331are kept equally. Then, the substrate S is nipped with the three contact members31to33to align the center SC of the substrate S with the center21C of the spin base21. As described above, the centering operation is performed only through the tiny movements of the contact members31to33made repeatedly. This achieves implementation of the centering operation with excellent throughput (effect A).

The completion of the centering operation is determined on the basis of variation in the load torque and the movements of the contact members31to33are stopped immediately. This makes it possible to finish the centering operation at appropriate time without damaging the substrate S (effect B). This also applies to embodiments described later.

Further, since the contact members31to33have linear regions312,322and332formed to intersect an XY plane as shown in field (a) ofFIG.4, still another effect is obtained. A contact member having a tip part finished into a semi-disk shape (see field (b) ofFIG.4) or a tip part finished into a sharp shape or a contact member having a roller shape is generally known as a technique for pushing and moving the end face Se of the substrate S in a horizontal direction. Therefore, the effects A and B described above are obtained by using contact members having these shapes.

However, for example, in a comparative example shown in field (b) ofFIG.4, a tip part393of a contact member39has a semi-disk shape. In this contact member39, a contact surface391facing the end face Se of the substrate S is finished into a convex shape toward the substrate S. Accordingly, on the contact surface391, a curved region392intersecting a virtual horizontal plane including the substrate S placed on the upper surface of the substrate holder2has a curved shape having a center of curvature located on the side of the contact member39. Thus, if the substrate S is placed on the upper surface of the spin base21with the notch NT facing the contact surface391, a part of the tip part393is in contact with the substrate S at two contact points CP1, CP2on the curved region392while entering the notch NT. As a result, at the time of centering, the contact surface391moves to a position P1closer to the substrate S by an eccentric deviation amount than a position P0where the contact surface391is positioned in contact with the end face Se of the substrate S. As a result, a pushing position of the contact member39deviates from a position for a precise centering process. For example, if the centering process was performed with the contact members31to33replaced by the contact members39in the centering mechanism3shown inFIG.3, the following experimental result was obtained. Here, if the centering process was performed with the substrate (semiconductor wafer having a radius of 150 mm) placed on the spin base21rotated by a suitable rotation angle (e.g. 32°, 180° or 328°) about the vertical axis AX and the notch NT facing the contact surface391, a deviation amount of the pushing position, i.e. the eccentric deviation amount reached up to 240 μm.

In contrast, in this embodiment, the contact surfaces311to331of the contact members31to33have a flat surface shape. Thus, as shown in field (a) ofFIG.4, a region (corresponding to an example of a “contactable region” of the invention) intersecting the virtual plane including the substrate S placed on the upper surface of the substrate holder2has a linear shape in each of the contact surfaces311to331. Moreover, any of these linear regions312,322and332is longer than an arc length Ln. Accordingly, if the substrate S is placed on the upper surface of the spin base21with the notch NT facing the contact surface321as shown inFIG.4, two contact points CP1, CP2on the linear region322are locked by shoulder parts of the notch NT, which can effectively prevent a part of the contact member32from entering the notch NT. Further, the contact surface321moves to a position P2closer to the substrate S by an eccentric deviation amount La than a position P0where the contact surface321is positioned in contact with the end face Se of the substrate S, but the eccentric deviation amount La is drastically smaller than an eccentric deviation amount Lb in the comparative example.

Here, when an eccentricity amount and an eccentricity direction were measured while a rotation amount of the substrate (semiconductor wafer having a radius of 150 mm) placed on the spin base21about the vertical axis AX was switched by 0.25° in a range of 326.25° to 329.75° in the centering mechanism3shown inFIG.3, experimental results shown inFIG.8were obtained.

FIG.8is a graph showing the eccentricity amount and the eccentricity direction corresponding to a positional relationship of the notch with the contact surface. InFIG.8, the rotation angle represents the positional relationship between the notch NT and the contact surface321. The entire notch NT is facing the contact surface321as shown inFIG.4at 328°, and the notch NT is deviated from the contact surface321in a circumferential direction of the substrate S at 327.25° or less or 328.75° or more. Further, inFIG.8, a rhombus mark represents the eccentricity amount after a centering operation, and a square mark represents the eccentricity direction after the centering operation. As is clear fromFIG.8, even if the centering process is performed in such a posture that the notch NT faces the contact surface321, the eccentricity amount can be suppressed up to about 11 μm. That is, by using the contact member32having the contact surface321configured as described above, the eccentric deviation amount can be drastically suppressed regardless of the position of the notch NT. This point applies also to the contact surface311of the contact member31and the contact surface331of the contact member33. As a result, centering accuracy can be drastically improved as compared to the comparative example by performing the centering process by sandwiching the substrate S placed on the upper surface of the spin base21by these contact surfaces311,321and331.

A combination of the centering mechanism3and the control unit9corresponds to the first embodiment of the centering device according to the invention, but the configurations of the contact surfaces311,321and331in the centering mechanism3are not limited to this. For example, the contact surfaces311,321and331may be finished such that contactable regions intersecting the XY plane are curved as shown inFIG.9(second embodiment).

FIG.9is a diagram schematically showing the configuration of a contact member adopted in the second embodiment of the centering device according to the invention and a relationship with a notch of a substrate. This second embodiment largely differs from the first embodiment in that contact surfaces311,321and331have a curved shape along an end face Se of a substrate S, and the other configuration is the same as in the first embodiment. Therefore, the following description is centered on points of difference and the same components are denoted by the same reference signs and are not described.

As shown in field (a) ofFIG.9, on a contact surface321, a curved region323intersecting a virtual horizontal plane including the substrate S placed on the upper surface of a substrate holder2corresponds to an example of the “contactable region” of the invention. That is, the contact surface321is finished such that a center of curvature of the curved region323is located on the side of the substrate S and a radius of curvature of the curved region323is larger than a radius of the substrate S. Accordingly, at the time of centering, the contact member32contacts the end face Se of the substrate S at one or two points in the curved region323if the contact member32is moved toward the end face Se of the substrate S. That is, as shown inFIG.9, if the substrate S is placed on the upper surface of a spin base21with a notch NT facing the contact surface321, two contact points P1, P2on the curved region323are locked by shoulder parts of the notch NT, which can effectively prevent a part of the contact member32from entering the notch NT. Further, the contact surface321moves to a position P3closer to the substrate S by an eccentric deviation amount Lc than a position P0where the contact surface321is positioned in contact with the end face Se of the substrate S, but the eccentric deviation amount Lc is smaller than the eccentric deviation amount La in the first embodiment. This point applies also to the contact surface311of the contact member31and the contact surface331of the contact member33.

Here, if an eccentric deviation amount by the notch NT (angle of 1.119°) provided in the substrate S (semiconductor wafer having a radius of 150 mm) was obtained while the radius of curvature was changed in multiple stages, an experimental result shown inFIG.10was obtained.FIG.10is a graph showing a change of the eccentric deviation amount in relation to a degree of curvature (radius of curvature) of the contact surface. As is clear fromFIG.10, the eccentric deviation amount L decreases as the radius of curvature approaches the radius of the substrate S. If the radius of curvature and the radius of substrate coincide, there is theoretically no influence of the notch NT. However, in consideration of tolerances of the substrate S, it is actually unusable to cause the radius of curvature to coincide with the radius of the substrate S. Therefore, in the second embodiment, the contact surfaces311,321and331are finished such that radii of curvature of the curved regions313,323and333are larger than the radius of the substrate S.

As described above, in the substrate processing apparatus10, a combination of the centering mechanism3and the control unit9corresponds to the first embodiment of the centering device according to the present invention. Specifically, the contact members31to33correspond to an example of a “first contact member,” an example of a “second contact member,” and an example of a “third contact member” of the present invention respectively.

The control unit9corresponds to an example of a “controller” of the present invention. The spin base21and the center21C correspond to an example of a “substrate support” and an example of the “center of the substrate support” of the present invention respectively. The suction pump24corresponds to an example of a “suction unit” of the present invention.

In the first embodiment described above, the two contact members32and33are moved in the D2direction (X2direction) and in the D3direction (X2direction) respectively by the multi-mover36. However, the multi-mover36may be replaced with a single mover for the contact member32and a single mover for the contact member33each having the same configuration as the single mover35. In this case, the single movers provided for the contact members31to33correspond to an example of a “first single mover,” an example of a “second single mover,” and an example of a “third single mover” of the present invention respectively.

Like in this case, if the single mover for the contact member32and the single mover for the contact member33are provided, both the D2direction and the D3direction are not required to conform to the X2direction but at least one of the D2direction and the D3direction may be changed from the X2direction (second embodiment).

FIG.11schematically shows a configuration in a third embodiment of the centering device according to the present invention. The third embodiment largely differs from the first embodiment in that the multi-mover36is replaced with a single mover37for the contact member32and a single mover38for the contact member33each having the same configuration as the single mover35, and that both the D2direction and the D3direction differ from the X2direction. In the third embodiment, like the cases of the sections (a) and (b) ofFIG.5and like the considerations given to the second movement amount and the third movement amount on the basis of these sections, the second movement amount and the third movement amount are set individually. The other configuration and the other operation are basically the same as those of the first embodiment.

Also in the third embodiment having the above-described configuration, the contact members31to33successively abut on the substrate S so the substrate S is nipped with the contact members31to33while distances from the center21C of the spin base21to the contact surfaces311,321, and331are kept equally. By doing so, the center SC of the substrate S is aligned with the center21C of the spin base21. In this way, the centering operation is performed only through tiny movements of the contact members31to33made repeatedly to achieve implementation of the centering operation with excellent throughput.

Note that the invention is not limited to the above embodiments and various changes other than the aforementioned ones can be made without departing from the gist of the invention. For example, in the above-described embodiments, nipping the substrate S with the contact members31to33, namely, completion of the centering operation is detected on the basis of variation in a load torque. The detection may be made by another method. In an exemplary configuration, the single mover35or38or the multi-mover36may be provided with a sensor such as a load cell or a strain gauge, and stress or strain may be detected by the sensor when the substrate S is nipped with the contact members31to33to output a detection signal. In this case, the control unit9determines nipping the substrate S with the contact members31to33on the basis of the detection signal from the sensor.

In the above-described embodiments, the present invention is applied to the centering device provided to the substrate processing apparatus10that performs the bevel etching process. Meanwhile, the centering device according to the present invention is applicable to every type of centering device provided to a substrate processing techniques that performs a process while rotating a substrate of a circular plate shape and to and every type of centering method. Also, the centering device according to the present invention may be used alone.

Further, although the substrate is centered using the three contact members in the above embodiments, the invention can be applied to a centering device using four or more contact members.

This invention can be applied to a centering technique for horizontally moving and positioning a substrate such that a center of the substrate is aligned with a center of a substrate support with the disk-like substrate provided with a cut such as a notch placed in a horizontal posture on the upper surface of the substrate support, and substrate processing apparatuses in general for processing a substrate utilizing the centering technique.