Substrate transfer apparatus, substrate transfer method, and non-transitory storage medium

A substrate transfer apparatus to transfer a circular substrate provided with a cutout at an edge portion thereof, includes: a sensor part including three light source parts applying light to positions different from one another at the edge portion, and three light receiving parts paired with the light source parts; and a drive part for moving the substrate holding part, wherein the three light source parts apply light to the light receiving parts so that whether or not a detection range of the sensor part overlaps with the cutout of the substrate is determined on the basis of an amount of received light by each light receiving part, and when it is determined that there is an overlap at any position, positions of the edge portion of the substrate are further detected with the position of the substrate displaced with respect to the sensor part.

CROSS REFERENCE TO RELATED APPLICATION

The present application is related to, claims priority from and incorporates by reference Japanese Patent Applications No. 2012-022047 filed on Feb. 3, 2012.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a substrate transfer apparatus for transferring a substrate between modules, a substrate transfer method, and a non-transitory storage medium storing a program for executing the substrate transfer method.

2. Description of the Related Art

In a manufacturing process of, for example, a semiconductor device, a plurality of treatment modules each performing treatment on a wafer being a substrate are provided in an apparatus and the wafer is sequentially transferred by a substrate transfer apparatus between the treatment modules, whereby predetermined treatments are performed. The substrate transfer apparatus includes a holding part holding the wafer.

For performing appropriate treatments on the wafer, it is required to accurately deliver the wafer to a predetermined position in the module. To this end, it is studied to detect the position of the edge portion of the wafer on the holding part by a detection part (sensor) and transfer the wafer on the basis of the detected position. For example, in Japanese Laid-open Patent Publication No. H08-031905, it is described to correct the transfer amount of the wafer between the modules on the basis of the detected position of the edge portion of the wafer so as to eliminate the positional displacement of the wafer in the module. It is also described in Japanese Laid-open. Patent Publication No. 2006-351884 to obtain a center position of the wafer from the detected positions of the edge portion and to conduct control for a transfer arm part to be able to move and mount the wafer to a transfer target position on the basis of the displacement amount between the center position and a predetermined reference position.

However, the wafer is not a round but has a cutout (notch) for positioning of the wafer formed at its edge portion. When a detection range of the detection part overlaps with the cutout, the position of the wafer at the holding part cannot be correctly detected any longer, and therefore, something needs to be done. Further, in the case of failure of the plurality of detection parts due to some problem, it is conceivable that the transfer of the wafer under treatment in the apparatus is stopped and an operator enters the apparatus to collect the wafer and removes the wafer. In this case, however, the treatment on the wafer is suspended in the apparatus and the throughput may greatly decrease. In such circumstances, it is desired to accurately detect the position of the wafer even when a part of the plurality of detection parts are unusable. The apparatuses in Japanese Laid-open Patent Publication No. H08-031905 and No. 2006-351884 in which these problems are not into consideration cannot solve the problems.

SUMMARY OF THE INVENTION

The present invention has been made in consideration of the above points and its object is to provide a technique capable of, when transferring a circular substrate having a cutout provided at an edge portion, accurately transferring the substrate to a module even with a small number of light source parts and light receiving parts pared with the light source parts which detect positions of an edge portion of the substrate respectively.

A substrate transfer apparatus of the present invention is a substrate transfer apparatus including a substrate holding part movable in a lateral direction to transfer a circular substrate provided with a cutout at an edge portion thereof from a first module to a second module, including:

a sensor part including three light source parts applying light to positions different from one another at the edge portion, and three light receiving parts paired with the light source parts, to detect positions of three points of the edge portion of the substrate held by the substrate holding part;

a drive part for moving the substrate holding part relative to the sensor part; and

a control part outputting control signals to control operations of the substrate holding part, the drive part, and the sensor part,

wherein the control part outputs the control signals to execute:

a first step of detecting positions of the edge portion of the substrate with the substrate holding part holding the substrate received from the first module located at a first position preset with respect to the sensor part;

a second step of detecting positions of the edge portion of the substrate with the substrate holding part located at a second position displaced from the first position with respect to the sensor part;

a third step of deriving, assuming that a state that a light irradiation region of the light source part is located at the cutout of the substrate is called an abnormal state, and based on detection results at the first step and the second step, any of results:a. that the abnormal state occurs at any of the first position and the second position and that position is able to be specified;b. that the abnormal state does not occur at any of the first position and the second position;c. that the abnormal state occurs at both of the first position and the second position; andd. that the abnormal state occurs at least at any of the first position and the second position but that position is not able to be specified; and

a fourth step of deciding, when a result at the third step is a or b, a delivery position of the substrate holding part with respect to the second module on the basis of the positions of the edge portion detected at the first position or the second position, and detecting, when the result is c or d, positions of the edge portion of the substrate with the substrate holding part moved to a third position different from the first position and the second position with respect to the sensor part to apply light to a position off the cutout of the substrate, and deciding the delivery position on the basis of the positions.

The present invention according to another aspect is a substrate transfer method using a substrate transfer apparatus including a substrate holding part movable in a lateral direction to transfer a circular substrate provided with a cutout at an edge portion thereof from a first module to a second module,

the substrate transfer apparatus including:

a sensor part including three light source parts applying light to positions different from one another at the edge portion, and three light receiving parts paired with the light source parts, to detect positions of three points of the edge portion of the substrate held by the substrate holding part; and

a drive part for moving the substrate holding part relative to the sensor part, and

the substrate transfer method including:

a first step of detecting positions of the edge portion of the substrate with the substrate holding part holding the substrate received from the first module located at a first position preset with respect to the sensor part;

a second step of detecting positions of the edge portion of the substrate with the substrate holding part located at a second position displaced from the first position with respect to the sensor part;

a third step of deriving, assuming that a state that a light irradiation region of the light source part is located at the cutout of the substrate is called an abnormal state, and based on detection results at the first step and the second step, any of results:a. that the abnormal state occurs at any of the first position and the second position and that position is specified;b. that the abnormal state does not occur at any of the first position and the second position;c. that the abnormal state occurs at both of the first position and the second position; andd. that the abnormal state occurs at least at any of the first position and the second position but that position is not able to be specified; and

a fourth step of deciding, when a result at the third step is a or b, a delivery position of the substrate holding part with respect to the second module on the basis of the positions of the edge portion detected at the first position or the second position, and detecting, when the result is c or d, positions of the edge portion of the substrate with the substrate holding part moved to a third position different from the first position and the second position with respect to the sensor part to apply light to a position off the cutout of the substrate, and deciding the delivery position on the basis of the positions.

The present invention according to still another aspect is a non-transitory storage medium storing a computer program used in a substrate transfer apparatus including a substrate holding part movable in a lateral direction to transfer a circular substrate provided with a cutout at an edge portion thereof from a first module to a second module,

wherein the computer program is to execute a substrate transfer method using the substrate transfer apparatus,

the substrate transfer apparatus including:

a sensor part including three light source parts applying light to positions different from one another at the edge portion, and three light receiving parts paired with the light source parts, to detect positions of three points of the edge portion of the substrate held by the substrate holding part; and

a drive part for moving the substrate holding part relative to the sensor part, and

the substrate transfer method including:

a first step of detecting positions of the edge portion of the substrate with the substrate holding part holding the substrate received from the first module located at a first position preset with respect to the sensor part;

a second step of detecting positions of the edge portion of the substrate with the substrate holding part located at a second position displaced from the first position with respect to the sensor part;

a third step of deriving, assuming that a state that a light irradiation region of the light source part is located at the cutout of the substrate is called an abnormal state, and based on detection results at the first step and the second step, any of results:a. that the abnormal state occurs at any of the first position and the second position and that position is specified;b. that the abnormal state does not occur at any of the first position and the second position;c. that the abnormal state occurs at both of the first position and the second position; andd. that the abnormal state occurs at least at any of the first position and the second position but that position is not able to be specified; and

a fourth step of deciding, when a result at the third step is a or h, a delivery position of the substrate holding part with respect to the second module on the basis of the positions of the edge portion detected at the first position or the second position, and detecting, when the result is c or d, positions of the edge portion of the substrate with the substrate holding part moved to a third position different from the first position and the second position with respect to the sensor part to apply light to a position off the cutout of the substrate, and deciding the delivery position on the basis of the positions.

According to the present invention, the light source part constituting the detection part applies light to the light receiving part at each position with the position of the substrate displaced with respect to the sensor part, and whether or not the detection range of the sensor part overlaps with the cutout of the substrate is determined on the basis of each amount of received light. When it is determined that there is an overlap at any position, the position of the substrate is further displaced with respect to the sensor part and positions of the edge portion of the substrate are detected. Consequently, it is possible to accurately deliver the substrate to a module while suppressing the number of required light source parts and light receiving parts.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1illustrates a perspective view of a transfer arm30that forms a substrate transfer apparatus and a group of modules to which a wafer W that is a circular substrate is delivered by the transfer arm30. An edge portion of the wafer W is provided with a notch N that is a cutout. A numeral11in the drawing denotes a housing that houses a module COT applying a resist to the wafer W. A wafer W is delivered to the module COT through a transfer port12and subjected to a resist coating treatment. The housing11faces a transfer path20for the wafer W in which the transfer arm30moves, and a plurality of heating modules21are provided to face the housing11across the transfer path20. The heating module21includes a heating plate on which the wafer W coated with the resist is mounted, and performs a heat treatment on the wafer W. A numeral22in the drawing denotes a transfer port for the wafer W in the heating module21.

The transfer arm30transfers the wafer W from a module on the upstream side (omitted inFIG. 1) to the resist coating module and then transfers the wafer W to the heating module21, and the wafer W is subjected to a series of treatments. The transfer arm30includes forks3(3A,3B) each forming a holding part for the wafer W, a base31, a rotation mechanism32, a lift table34and a substrate edge position detection mechanism40.

The two forks3A,3B are supported on the base31via supporting parts33A,33B respectively to overlap one above the other, and advance and retract independently of each other on the base31. The base31is provided on the lift table34to be rotatable around the vertical axis by means of the rotation mechanism32. The lift table34is provided to be surrounded by a frame35extended in the vertical direction and lifts up and down in the vertical direction (a Z-direction inFIG. 1). A mechanism for lifting up and down the lift table34is provided inside the frame35, A Y-axis guide rail linearly extending in a lateral direction (a Y-direction inFIG. 1) is provided on a housing36provided under the heating modules21. The frame35is connected to the guide rail. The frame35is therefore configured to move in the Y-direction. This configuration allows the forks3A,3B to be movable in the Z-direction, the Y-direction and an X-direction perpendicular to the Z and Y-directions and rotatable around the vertical axis and to access each of the aforementioned modules and deliver the wafer W to the module.

The base (moving body)31and the forks3A,3B of the transfer arm30will be further explained referring also toFIG. 2,FIG. 3,FIG. 4that are a perspective view, a plan view, and a side view thereof. The forks3A,3B are configured to be identical with each other, and therefore the fork3A will be explained as a representative. The fork3A is formed in a flat arc shape and configured to surround the periphery of the wafer W to be transferred as illustrated inFIG. 3. The inner periphery of the fork3A is formed to be slightly larger than the outer periphery of the wafer W so that the wafer W can be transferred even if the position of the wafer W is slightly displaced during transfer inside and outside the module.

Further, on the lower side of the inner periphery of the fork3A, four holding claws37on which a rear surface edge portion of the wafer W will be mounted are formed at intervals to project toward the inside of the fork3A. Each of the holding claws37is provided with a vacuum suction port38. When the rear surface edge portion of the wafer W is mounted on the holding claws37, the vacuum suction ports38vacuum-suck the edge portion to hold the wafer W on the holding claws37. The vacuum suction ports38are connected to a pipe39provided in the fork3A. The vacuum suction performed as described above enables positioning of the horizontal position of the edge portion of the wafer W.

The fork3advances and retracts on the base31as described above, but is usually located at a retracted position on the base31. For delivering the wafer W to a module, the fork3moves to a delivery position advanced from the retracted position.FIG. 3andFIG. 4indicate a state that the forks3A,3B has moved to the retracted position and the delivery position respectively. The transfer arm30receives a wafer W from a module by one fork and delivers a wafer W to the module by the other fork. In short, the transfer arm30acts to replace the held wafers W with respect to the module.

Subsequently, the substrate edge position detection mechanism40will be explained. The substrate edge position detection mechanism40that is a sensor part includes four detection parts4(4A to4D), which are provided to detect positions of the edge portion of the wafer W respectively when the fork3A or3B is located at the retracted position (reference position) on the base31while holding the wafer W. The detection parts4A to4D are provided at intervals along the edge portion of the wafer W to be able to detect four edge positions of the wafer W different from each other.

The detection parts4are composed of four light source parts41(41A to41D) and four light receiving parts42(42A to42D) paired with the respective light source parts41. The light source parts41(41A to41D) include, for example, LED (Light Emitting Diodes) and are provided on the base31and arranged, for example, below the fork3A,3B at the retracted position. Further, the light source parts41include not-illustrated lenses and radiate light of the LED vertically upward via the lenses as illustrated by arrows inFIG. 4. Further, the irradiation region of the light of the light source part41is formed, in a plan view, linearly from the outside to the center part side of the wafer W on the fork3at the retracted position.

The light receiving part42is a linear image sensor (LIS) composed of a plurality of linearly arranged light receiving elements. The light receiving element is composed of, for example, a CCD (Charge Coupled Device). The light receiving parts42are provided on the base31via a supporting member43and arranged above the forks3A,3B. More specifically, the light source parts41and the light receiving parts42paired with each other are provide above and below the wafer W held by the fork3A,3B at the retracted position intervening therebetween. The light receiving elements of the light receiving part42are arranged from the outside to the center portion side of the wafer W to be able to receive the light from the light source part41.

At the time when the fork3holds the wafer W and stops at the retracted position and at a position slightly advanced from the retracted position as will be described later, the light source parts41A to41D emit light upward from below. The emitted light is received by the light receiving parts42A to42D provided above the fork3A. In this event, a later-described control part can decide the position of the boundary between a pixel which has received the light and a pixel which has not received the light on the basis of detection values of the CCDs that are pixels of the light receiving parts42A to42D. The decided position of the boundary can be expressed by coordinates with a predetermined position on an XY-plane as an original point, and calculation for calculating the center position and the radius of the wafer W can be performed as will be described later. A Y-direction within the Y-plane is the moving direction of the base31, and an X-direction is a direction which is perpendicular to the Y-direction and in which the fork3moves.

The concrete appearance that the light receiving part42recognizes the position of the boundary, namely, the position of the edge portion of the wafer W will be explained usingFIG. 5.FIG. 5is a graph schematically illustrating the relationship between the positions of the wafer W and the fork3and the amount of received light by the pixel corresponding to each light receiving element in the light receiving part (linear image sensor)42, in which the detection value of the pixel which has not received the light emitted from the light source part41(hereinafter, referred to as an “amount of received light”) is a first value n1 and the amount of received light by the pixel which has received the light emitted from the light source part41is a second value n2. In this event, the position of the edge portion of the wafer W can be detected as a position E where the amount of received light by each pixel varies between the first value n1 and the second value n2. When the amount of received light is processed as 8-bit data, the first value n1 can be, for example, 0 and the second value n2 can be, for example, a predetermined value equal to or less than 255. InFIG. 5, numbers (pixel numbers) are given to the pixels from the inside of the wafer W, and the pixel number of the light receiving element from which the light emitted from the light source part41is shielded by the fork3when the fork3retracted on the base31is located at the reference position (retracted position) is 900. As described above, the light receiving part42is configured as a CCD line sensor that detects the position of the edge portion of the wafer W along the direction in which the light receiving part42extends.

The configuration of the detection part4will be further explained. As illustrated inFIG. 6, the detection part4has a CCD line sensor control part44, a digital-analogue converter (DAC)45, and an analogue-digital converter (ADC)46in addition to the light source part41and the light receiving part42. The CCD line sensor control part44is a timing generator that shifts an operation timing of each light receiving element (CCD element) of the CCD line sensor forming the light receiving part42on the basis of a clock signal from a not-illustrated clock to move charges, and also performs current control to the light source part41. In order to input a digital control signal from the CCD line sensor control part44into the light source part41, the DAC45performs analog conversion. In order to output an analog output signal being a detection signal from the light receiving part42to the later-described control part5, the ADC46performs digital conversion.

By the above configuration, the control signal from the CCD line sensor control part44is analog-converted by the DAC45and inputted into the light source part41. This causes the LED of the light source part41to emit light. The light receiving part42that has received the output light from the light source part41outputs a signal corresponding to the amount of received light of each pixel by movement of charges in the light receiving part42on the basis of timing of the control signal from the CCD line sensor control part44. This signal (detection value) is inputted into the control part5via the ADC46.

The transfer arm30includes the control part5composed of a computer, and operations of its parts are controlled by the control part5. The control will be explained referring also to the block diagram of the control part5illustrated inFIG. 7. The control part5controls, via an amplifier47, five motors M1to M5in total that are motors M1, M2for driving in the X-axis provided on the base31for driving the forks3A,3B, a motor M3for driving in the Y-axis provided on the housing36for driving the base31in the Y-direction, a motor M4for driving in the Z-axis provided on the frame35for driving the lift table34in the Z-direction, and a motor M5for rotation driving provided on the rotation mechanism32. The rotation operations of the motors M1to M5are transmitted to the fork3, the base31, the rotation mechanism32, and the lift table34by a transmission mechanism such as a timing belt.

The parts of the transfer arm30linearly move in the X-, Y- and Z-directions respectively by the distances corresponds to the rotation mounts of the motors M1to M5to rotate the rotation mechanism32. To each of the motors M1to M5, an encoder48that outputs pulses according to the rotation amount of the motor and a counter49that counts the number of pulses are further connected. The counter49outputs a signal according to the count to the control parts5, and the control parts5can thereby detect the position of each of the parts of the transfer arm30. For preventing complication of the drawing, only one set of the motor M, the encoder48and the counter49is illustrated inFIG. 7.

As illustrated inFIG. 7, the control part5includes a calculation processing part51, a program storage part52, a display part53, an alarm generation part54, and a storage part55. A numeral50in the drawing denotes a bus. The calculation processing part51is a data processing part having, for example, a memory and a CPU (Central Processing Unit). The calculation processing part51reads programs recorded in the program storage part52, transmits control signals to the respective parts according to instructions (commands) included in the programs to execute transfer of the wafer W.

The program storage part52is a computer-readable non-transitory storage medium and stores a normal mode execution program56and a temporary mode execution program57that are transfer modes for the wafer W. The modes will be described later. The program storage part52is composed of, for example, a flexible disk, a compact disk, a hard disk, a magnetoptical disk (MO) or the like. The display part53is composed of, for example, a computer screen.

Further, the control part5also controls the operations of the respective modules and can select various substrate treatments in the modules and perform input operation of parameters in the substrate treatments through the display part53. For example, when one of the detection parts4becomes unusable, the alarm generation part54generates an alarm sound reporting the fact. The storage part55stores the positions of the edge portion (edge positions) of the wafer W detected by the detection parts4A to4D and the calculation values obtained by executing the aforementioned modes as illustrated inFIG. 8. The calculation values will be described when the modes are explained.

Incidentally,FIG. 7illustrates a longitudinal sectional view of the heating module21. Briefly explaining the configuration of the heating module21to explain the transfer of the wafer W by the transfer arm30, a numeral23in the drawing denotes a heating plate on which the wafer W is to be mounted. A numeral24denotes a raising and lowering pin which is raised and lowered by a raising and lowering mechanism25to deliver the wafer W between the fork3A,3B and the heating plate23. In other words, the wafer W moved to the heating plate23is vertically moved from the position held by the fork3and delivered to the heating plate23.

Here, the outline of the transfer of the wafer from the resist coating module COT to the heating module21by the transfer arm30will be explained referring toFIG. 9,FIG. 10. In the drawings inFIG. 9and subsequent thereto, the fork3and the base31are illustrated while being slightly simplified for explanation. As described above, the fork3holds the wafer W to surround the side periphery of the wafer W delivered from the resist coating module COT. When the wafer W is held in this manner, if a center position o of the wafer W when mounted on the fork3as illustrated inFIG. 9vertically aligns with a preset appropriate position p of the fork3, the base31and the fork3move so that the appropriate position p of the fork3vertically aligns with an appropriate position q (indicated as coordinates (α, β) in the drawing) of the heating plate23, whereby the wafer W can be mounted so that the center position o of the wafer W vertically aligns with the appropriate position q, namely, at an appropriate position of the heating plate23.

However, in the case where the center position o of the wafer W is displaced from the appropriate position p of the fork3as illustrated inFIG. 10, if the base31and the fork3move so that the appropriate position p of the fork3vertically aligns with the appropriate position q of the heating plate23, the wafer W will be delivered with the center position o of the wafer W displaced from the appropriate position q of the heating plate23by the displace amount between the center position o of the wafer W and the appropriate position p of the fork3. The displacement amounts of the center position o of the wafer W with respect to the appropriate position p in the X-direction and the Y-direction in the drawing are ΔX and ΔY respectively. Further, the center position o when displaced from the appropriate position as described above is indicated as o′.

Hence, the coordinate positions of the edge portion of the wafer W in the XY-plane are detected by the detection parts4, and the center position (center coordinates) o′ of the wafer W in the XY-plane is obtained by calculation on the basis of the detection results. Then, at the time when the wafer W is delivered to the heating module21, the position in the Y-direction of the base31and the position in the X-direction of the fork3are controlled so that the displace amounts between the center position o′ and the appropriate position p of the fork3are eliminated.

FIG. 10illustrates an example where the center position o′ is displaced from the appropriate position p by ΔX to the heating plate23side and ΔY in the moving direction of the base31from the resist coating module COT. In this case, the positions of the fork3and the base31are corrected so that the appropriate position p of the fork3at the delivery of the wafer W to the heating plate23is set to (α−ΔX, β−ΔY) that is displaced by ΔX, ΔY from the coordinates (α, β) of the appropriate position q of the heating plate23. In other words, the position of the fork3when delivering the wafer W with respect to the heating plate23is changed to correspond to the displacement amounts between the center position o′ and the appropriate position p. Thus, the wafer W is delivered so that the center position o′ of the wafer W vertically aligns with the appropriate position q of the heating plate23. The coordinate data on the appropriate position q of the module is stored in the storage part55of the control part5, and calculation is performed so that the delivery is performed on the basis of the thus stored data.

However, since the wafer W is provided with the notch N as described above, the detection range of any one of the detection parts4A to4D overlaps with the notch N, for example, as illustrated inFIG. 11when the fork3is located at the retracted position, namely, the light from the light source part41is applied to the notch N in some case.FIG. 11illustrates an example where the detection range of the detection part4A overlaps with the notch N. In this case, the detection part4A overlapping with, the notch N detects a position inside the outer shape of the wafer W as the position of the edge portion, and therefore the center position calculated using the detection result of the detection part4A (indicated as of in the drawing) is displaced from the actual center position o. To prevent such a situation, the control part5is provided with a function of determining whether or not the notch N overlaps with the detection range, and when determining that there is an overlap, moving the fork3to displace the notch N from the position of the detection part4, and calculating the center position again.

Then, when all of the detection parts4A to4D are usable, the control part5executes the normal mode by the program56, and when one of the detection parts4A to4D becomes unusable due to fault or the like, executes the temporary mode by the program57. The modes execute the determination of an overlap of the notch N and the calculation of the center position by respective different processes.

Before explanation of how to perform the determination of an overlap of the notch N, the method of calculating the coordinates of the center position (center coordinates) from the positions of the edge portion of the wafer W will be explained referring toFIG. 12. The positions of the edge portion of the wafer W on the light receiving parts42when the center position o of the wafer W is located to vertically align with the already-described appropriate position p of the fork3are indicated as an a point, a b point, a c point, and a d point respectively. Further, angles formed between directions in which the four light receiving parts42A to42D extend and the Y-axis are θ1, θ2, θ3, θ4.

Further, the position of the held wafer W when the held wafer W is displaced with respect to the appropriate position p is a displacement position, and the positions of the edge portion of the wafer W at the displacement position on the light receiving parts42are an a′ point, a b′ point, a c′ point, a d′ point respectively.

The distances between the a point, the b point, the c point, the d point and the a′ point, the b′ point, the c′ point, the d′ point on the light receiving parts42are Δa, Δb, Δc, Δd respectively. In this event, Δa, Δb, Δc, Δd are
Δa[mm]={(the number of pixels at thea′ point)−(the number of pixels at theapoint)}×pixel interval[mm]  (1)
Δb[mm]={(the number of pixels at theb′ point)−(the number of pixels at thebpoint)}×pixel interval[mm]  (2)
Δc[mm]={(the number of pixels at thec′ point)−(the number of pixels at thecpoint)}×pixel interval[mm]  (3)
Δd[mm]={(the number of pixels at thed′ point)−(the number of pixels at thedpoint)}×pixel interval[mm]  (4)

Note that, for example, the number of pixels at the a point means the number of pixels from the start point on the center side of the wafer W at the light receiving part42to the a point.

Then, the coordinates of the a point to the d point and the a′ point to the d′ point are expressed as following Expressions (5) to (12). In Expressions, R is the radius of the wafer W. Further, X, Y are coordinates of the appropriate position p when the fork3has received the wafer W at the delivery position from each module and moved to the retracted position, namely, an X-coordinate, a Y-coordinate of the center position o when the wafer W is appropriately held by the fork3. The value of R and the coordinates of o are preset known values.

Accordingly, coordinates of the a′ point (X1′, Y1′), the b′ point (X2′, Y2′), the c′ point (X3′, Y3′), and the d′ point (X4′, Y4′) can be found by Expression (6), Expression (8), Expression (10), and Expression (12).

From any three points of thus calculated a′ point, b′ point, c′ point, d′ point, coordinates (X′, Y′) of the center position o′ of the wafer W at the displacement position can be calculated. For example, the expressions of calculating the coordinates (X′, Y′) of the center position o′ at the displacement position, for example, from the three points of the a′ point (X1′, Y1′), the b′ point (X2′, Y2′), the c′ point (X3′, Y3′) are expressed by following Expression (13) and Expression (14).

Incidentally, to perform the determination between an overlap of the notch N and the detection range of the detection part4, a radius R′ of the wafer W that is calculated from the center position calculated from the three edge positions and one of the three edge positions is used. For example, when the center coordinates are calculated from the a′ point, the b′ point, the c′ point, the radius R′ is calculated by following Expression (15).
R′=√{square root over ({(X′−X2′)2+(Y′−Y2′)2})}  (15)

In the above Expression (15), the radius R′ is calculated from the center coordinates o′ and the coordinates of the b′ point. However, when the center coordinates o′ are calculated from the three edge positions, which edge coordinates among those of the edge positions are used to calculate the radius are decided in advance. For example, the coordinates of the a′ point are used when the center coordinates o′ are calculated from the coordinates of the a′ point, the b′ point, the d′ point, and the coordinates of the c′ point are used when the center coordinates o′ are calculated from the coordinates of the b′ point, the c′ point, the d′ point, and the coordinates of the d′ point are used when the center coordinates o′ are calculated from the coordinates of the a′ point, the c′ point, the d′ point.

Next, the method of determining the presence or absence of an overlap between the notch N and the detection range of the detection part4and the handling when there is an overlap as a result of the determination in the normal mode will be explained. For convenience of explanation, the center coordinates (center position) and the radius calculated from the a′ point, the b′ point, the d′ point are o′1and R′1respectively, and the center coordinates and the radius calculated from the a′ point, the b′ point, the c′ point are o′2and R′2respectively. Further, the center coordinates and the radius calculated from the b′ point, the c′ point, the d′ point are o′3and R′3respectively, and the center coordinates and the radius calculated from the a′ point, the c′ point, the d′ point are o′4and R′4respectively.FIG. 13illustrates an example of the positional relationship between the wafer W and the detection parts4in which the fork3holding the wafer W is located at the retracted position (reference position). The notch N does not overlap with any of the detection ranges of the detection parts4A to4D. In this case, when four center positions o′ (o′1to o′4) and radii R′ (R′1to R′4) are obtained using three of the a′ to d′ points as described above, the four radii R′ fall within a normal range, and a value of maximum value−minimum value of them is therefore equal to or less than a preset threshold value. Therefore, the control part5determines that the detection parts4do not overlap with the notch N, calculates an average value of the obtained four center positions o′1to o′4, and sets the calculated value as the center position o′.

FIG. 14illustrates another example of the positional relationship between the wafer W and the detection parts4in which the notch N overlaps with the detection range of the detection part4A.FIG. 14illustrates the center positions o′1to o′4calculated at this time. Since an overlap occurs at this time, two of the radii R′1to R′4are shorter than the actual radius of the wafer W that is a known value. In the example illustrated inFIG. 14, R′2and R′4are thus shorter. Accordingly, the calculated value of maximum value−minimum value of the radius R′ is larger than threshold value. Consequently, it can be determined that the notch N overlaps with the detection range of any of the detection parts4A to4D.

The radius R′ calculated using the detection parts4whose detection ranges do not overlap with the notch N has a normal value that is the same as the actual radius as a matter of course. However, even the radius R′ calculated using the data of the detection part4overlapping with the notch N sometimes falls within the normal range due to displacement of the calculated center position o′ from the actual center position of the wafer W to the cutout direction of the notch N. The radius R′3obtained from the b′ point, the c′ point, the d′ point corresponds to that case in the example inFIG. 14.

Hence, to specify the detection part not overlapping with the notch N, the control part5causes the fork3to slightly advance to displace the positions of the detection parts4and the wafer W as illustrated inFIG. 15. The distance of the advance is, for example, 1 mm, and the position advanced in this manner is a first slightly advanced position. The control part5calculates again the center positions o′1to o′4and the radii R′1to R′4at the first slightly advanced position.

An upper section ofFIG. 16illustrates the appearance that the center positions o′1to o′4move in XY-coordinates, for example, taking a predetermined position of the base31as an original point. In the drawing, the center positions o′1to o′4obtained at the retracted position are indicated by white points, and the center positions o′1to o′4obtained at the first slightly advanced position are indicated by black points. Comparing the center positions o′ at the retracted position with the center positions o′ at the first slightly advanced position, the positions in the Y-direction of some of the center positions o′ calculated using the detection part4overlapping with the notch N move because of change of the positions of the detection parts4with respect to the notch N, as illustrated in the drawing.

A lower section ofFIG. 16is a conceptual view illustrating the movements of the center positions o′1, o′2, o′4incorrectly detected due to the notch N as seen from the correctly detected center position o′3when the wafer W is moved such that the notch N gradually gets out of the detection range of the detection part4A, and illustrates the movement of each coordinates o′ after subtracting therefrom the movement amount of the fork3between the retracted position and the first slightly advanced position. The center positions incorrectly calculated as described above move as if to approach the correctly calculated center position. Note that when the wafer W is moved so that the overlap of the detection range of the detection part4A with the cutout of the notch N gradually increases, the other center positions o′1, o′2, o′4move to separate from the correctly calculated center position o′3.

Then, the center position calculated from the combination of the detection parts4(4B,4C,4D in this example), including the detection part4overlapping with the notch N at the retracted position as described above and calculating the same radius R′ as the normal value, changes in the Y-direction because the detection position with respect to the notch N varies between the inside and the outside of the wafer W. More specifically, the detection parts4in combination by which the radius R′ calculated at the retracted position has the normal value and no change occurs in the Y-direction in comparison between the center positions o′ calculated at the retracted position and at the first slightly advanced position can be specified as the detection parts4not overlapping with the notch N, and the center position o′ obtained from the combination can be decided as the correct center position of the wafer W. Also in the case where the detection part4other than the detection part4A overlaps with the notch N, the center position of the wafer W is specified in the similar manner.

The storage part55of the control part5stores data on the coordinates at the edge positions, the center coordinates o′1to o′4, and the radii R′1to R′4obtained by the detection parts4A to4D at each of the reference position (retracted position) and the first slightly advanced position as illustrated inFIG. 8to be able to perform the above calculation. Further, to enable the determination of the presence or absence of change in the Y-direction of the center position as described above, a region is provided which stores the calculation result of the difference in a Y component of the center coordinates between the reference position and the first slightly advanced position. The control part5recognizes that there is a change in the Y component when the calculated difference exceeds a predetermined range, and recognizes that there is no change when the difference does not exceed the range.

Though the detection method of the notch N using the detection parts4A to4D and the calculation method of the normal center position have been explained, a series of operations in the normal mode will be explained along the flow inFIG. 17taking, as an example, the transfer of the wafer W from the resist coating module COT to the heating module21. The base31is located to face the resist coating module COT, and the fork3A advances from the base31to the delivery position and receives a wafer W from the resist coating module COT, and then moves to the retracted position (Step S1). The light source parts41of the detection parts4A to4D apply light to the light receiving parts42, and the detection parts4A to4D obtain the coordinates of the edge positions of the wafer W. Then, on the basis of the coordinates of the edge positions, the center coordinates o′1to o′4and the radii R′1to R′4are calculated and stored (Step S2). The control part5uses the maximum value and the minimum value of the radii R′1to R′4and determines whether or not the value of maximum value−minimum value is larger than the preset threshold value (Step S3).

When it is determined that the value is not larger than the threshold value, it is determined that the detection range of any of the detection parts4does not overlap with the notch N, and the respective average values of the X components and the Y components of the center coordinates o′1to o′4are calculated, and the average values are set as the center coordinates o′ (X′, Y′). Then, as has been explained forFIG. 10, the displacement amounts ΔX and ΔY with respect to the appropriate coordinates p(X, Y) of the fork3A are calculated.
ΔX(mm)=X′−X(16)
ΔY(mm)=Y′−Y(17)

Then, as has been explained forFIG. 10, the coordinate position of the appropriate position p of the fork3when delivering the wafer W are calculated, on the basis of the ΔX and ΔY and the coordinates of the appropriate position of the heating plate23of the heating module21, so that the center coordinates o′ vertically align with the appropriate position q of the heating plate23of the heating module21. In short, the position of the base31and the position of the fork3when delivering the wafer W are calculated. Then, the base31moves to the position calculated as described above, and the fork3advances to the calculated position toward the heating module and mounts the wafer W so that the center position o′ of the wafer W vertically aligns with the appropriate position q of the heating plate23(Step S4).

When the value of maximum value−minimum value of the calculated radius R′ is determined to be larger than the threshold value at Step S3, it is determined that the detection range of any of the detection parts4overlaps with the notch N. The fork3A advances to the first slightly advanced position, the light sources41apply light, and the detection parts4A to4D obtain the coordinates of the edge positions similarly at Step S2. Then, the center coordinates o′1to o′4and the radii R′1to R′4at the first slightly advanced position are calculated (Step S5). Then, the difference between the Y components of the center coordinates obtained respectively at the retracted position and the first slightly advanced position are calculated.

The combination of the detection parts4by which the radius R′ calculated at the retracted position falls within the normal range and the difference in the Y component falls within the preset range is specified, and the center coordinates o′ calculated by the combination is set as the actual center coordinates o′. For the center coordinates after specifying the combination, the data calculated at the above Step S2may be used or the data calculated at this Step S6may be used. Then, similarly at Step S4, the displacement amounts ΔX and ΔY with respect to the appropriate position p of the fork3are calculated, and the wafer W is transferred so that the center coordinates o′ vertically align with the appropriate position q of the heating plate23(Step S6). The above series of operations are controlled by the normal mode execution program56.

Subsequently, the method of determining the presence or absence of an overlap between the notch N and the detection range of the detection part4and the handling when there is an overlap as a result of the determination in the temporary mode will be explained. As in the normal mode, the fork3holding the wafer W moves to the retracted position, three detection parts4among the four detection parts4A to4D except the unusable detection part are used to detect the edge positions of the wafer W, and the radius R′ and the center coordinates o′ of the wafer W are calculated on the basis of the edge positions. Thereafter, the fork3moves to the first slightly advanced position, the three detection parts4are used to detect the edge positions of the wafer W, and the radius R′ and the center coordinates o′ of the wafer W are calculated on the basis of the edge positions.

Here, if the detection range of one of the three detection parts4overlaps with the notch N at the retracted position or the first slightly advanced position as has been explained in the normal mode, the radius R′ calculated in the overlap state sometimes becomes smaller than the normal range. Further, even if both the radii R′ calculated at the retracted position and the first slightly advanced position fall within the normal range, the Y component of the center coordinates o′ changes between the retracted position and the first slightly advanced position.

As has been described, the radius R′ of the wafer W is obtained as the distance between the center coordinates o′ and the coordinates detected by the detection part4located at the middle in the arrangement direction of the three detection parts4where the arrangement interval is shortest as seen in the peripheral direction of the wafer W. Thus, when the detection range of any of the detection parts4adjacent in the peripheral direction to the unusable detection part4overlaps with the notch N, the radius R′ becomes smaller than the actual radius. When the detection range of the detection part4opposite to the unusable detection part4across the center of the wafer W overlaps with the notch N, the radius R′ falls within the normal range but the Y component varies.

FIG. 18illustrates an example where the detection part4C becomes unusable, in which the detection range of the detection part4A overlaps with the notch N when the fork3is located at the retracted position.FIG. 19illustrates a state that the fork3has moved to the first slightly advanced position. As illustrated inFIG. 18,FIG. 19, the position of the notch N with respect to the detection part4A is displaced, whereby the position of o′1calculated by the detection parts4A,4B,4D is displaced. Accordingly, the control part5recognizes that the detection part4A overlaps with the notch N at the retracted position and/or the first slightly advanced position.

Hence, the fork3further advances by a preset distance as illustrated inFIG. 20. The advance distance is a distance enough for the notch N to get out of the detection range. Then, at the advanced position (regarded as a second slightly advanced position), the detection parts4A,4B,4D are used to detect the edge positions of the wafer W, and the accurate center position o′ is calculated on the basis of the edge positions. Accordingly, the storage part55of the control part5includes a storage region for storing the edge positions at the second slightly advanced position and the center position calculated from the edge positions as illustrated inFIG. 8. Also when the detection part other than the detection part4C becomes unusable or when the detection part4other than the detection part4A overlaps with the notch N, the detection of the center position is similarly performed.

Though the case where the Y component of the center coordinates changes has been explained inFIG. 18toFIG. 20, other cases will be explained. If both the radii R′ calculated at the retracted position and the first slightly advanced position are shorter than the normal range, the notch N overlaps with the detection range of any of the detection parts4at the retracted position and the first slightly advanced position, so that the fork3is moved to the second slightly advanced position and the center coordinates are calculated as in the case of the Y component changes.

The case where there is no change in the Y component of the center coordinates at the retracted position and the first slightly advanced position, only the radius R′ calculated at the retracted position is smaller than the normal range, and the radius R′ at the first slightly advanced position falls within the normal range shows that the detection range overlaps with the notch N at the retracted position but the detection range gets out of the notch N at the first slightly advanced position. Accordingly, the center coordinates obtained from the edge positions obtained at the first slightly advanced position are regarded as, the correct center coordinates of the wafer W.FIG. 21,FIG. 22illustrate such an example in which the detection part4D is unusable and the notch N overlaps with the detection part4A at the retracted position. In this case, the center coordinates o′2obtained at the first slightly advanced position are the correct coordinates, and therefore the fork3is not moved to the second slightly advanced position.

The case where there is no change in the Y component of the center coordinates at the retracted position and the first slightly advanced position, only the radius R′ calculated at the first slightly advanced position is smaller than the normal range and the radius R′ at the retracted position falls within the normal range shows that the detection range overlaps with the notch N at the first slightly advanced position but the notch N is out of the detection range at the retracted position. Accordingly, the center position obtained from the edge positions obtained at the first slightly advanced position is regarded as the correct center position of the wafer W, and the fork3is not moved to the second slightly advanced position.

A series of operations in the temporary mode will be explained along the flow inFIG. 23taking, as an example, the transfer of the wafer W from the resist coating module COT to the heating module21mainly for the different points from those in the normal mode. It is assumed here that the detection part4C is unusable as in the case ofFIG. 18toFIG. 20. Similarly at the above Step S1, for example, the fork3A receives a wafer W from the resist coating module COT and moves to the retracted position (Step T1), the light source parts41apply light at the retracted position, and the detection parts4A,4B,4D obtain the coordinates of the edge positions. Then, on the basis of the coordinates of the edge positions, the center coordinates o′ (o′1) and the radius R′ (R′1) are calculated (Step T2). Thereafter, the fork3A moves to the first slightly advanced position, the light source parts41apply light, and the detection parts4A,4B,4D obtain the coordinates of the edge positions of the wafer W at the first slightly advanced position. Then, the center coordinates o′1and the radius R′1are calculated on the basis of the coordinates of the edge positions (Step T3).

Thereafter, the difference between the Y components of the center positions o′1obtained at Step T2and Step T3as already described is calculated and determined to fall within an allowable range. When the difference falls within the allowable range, whether or not the radii R′1calculated at Steps T2, T3respectively fall within the normal range is determined. In other words, whether or not the detection range of any of the detection parts4A,4B,4D overlaps with the notch N at the retracted position and the first slightly advanced position is determined (Step T4). When it is determined that only one of the radii R′1falls within the normal range, the center coordinates obtained at the same step as that for the radius R′1are decided as the normal center coordinates. When it is determined that both of the radii R′1fall within the normal range, any one of the center coordinates calculated at Steps T2T3, for example, the center coordinates calculated at Step T2are decided as the normal center coordinates. Then, on the basis of the center coordinates decided in such a manner, the wafer W is transferred as in the normal mode (Step T5).

When it is determined that the difference in the Y component of the center coordinates o′1does not fall within the allowable range and when it is determined that the radii R′1calculated at Steps T2, T3do not fall within the normal range, the fork3A is moved to the second slightly advanced position, the light source parts41apply light with the notch N being out of the detection ranges of the detection parts4, and the coordinates of the edge positions of the wafer W are obtained. The center coordinates o′1are calculated on the basis of the coordinates of the edge positions (Step T6), the displacement amounts ΔX and ΔY with respect to the appropriate position p of the fork3A are calculated on the basis of the center coordinates o′1calculated at Step T6, and the wafer W is transferred so that the center coordinates o′1vertically align with the appropriate position q of the heating plate23(Step T7).

Incidentally, depending on the holding position of the wafer W by the fork3, the wafer W is sometimes out of the detection range of any of the detection parts4, for example, when the fork3A advances to the second slightly advanced position. This is the case where the amount of received light having the first value n1 is not detected, but only the amount of received light having the second value n2 is detected in the above schematic view inFIG. 5. In such a case, the edge positions of the wafer W cannot be detected, so that the transfer of the wafer W by the transfer arm30is stopped and a warning indicating the fact that the transfer stop has occurred is displayed on the display part53provided in the control part5and an alarm sound is generated from the alarm generation part54provided in the control part5. The above-described series of operations are controlled by the temporary mode execution program57.

Subsequently, a switching operation from the normal mode to the temporary mode will be described. This switching is automatically performed when abnormality of the light source part41or the abnormality of the light receiving part42in each detection part4is detected, and the wafer W held by the fork3at the occurrence of the abnormality and subsequent wafers W are transferred in the temporary mode.

The light source part41is composed of, for example, the LED as described above, and the abnormality that will occur in the LED is turnoff of the LED, decrease in light quantity of the LED, contamination of the lens provided in the LED, wire breakage of a cable between the control part5and the LED or the like. The detection of the above abnormality in the light source part41is performed, for example, every time the fork3holding the wafer W moves to the retracted position when the edge positions of the wafer W are detected, by detecting the light quantity of light emitted from the light source part41by means of the light receiving element arranged at a position where it is not usually shielded by the wafer W held by the fork3.

FIG. 24is a graph schematically illustrating, similarly to already-describedFIG. 5, the relationship between the pixel number and the amount of received light of the light receiving part42which will be explained referring toFIG. 24. In the case where the above abnormality occurs in the light source part41, when the control part5transmits a signal to the light source part41to emit light, the amount of detected light changes from the second value n2 as exemplified inFIG. 24. When the amount of received light becomes lower than the allowable value, the detection part4including the light source part41is made unusable, and generation of an alarm sound and display of a warning on the screen are performed, and the operation mode is switched from the normal mode to the temporary mode. In other words, in this example, the center position of the wafer is calculated and the abnormality of the light source part41is determined, whereby a poor condition of the light source part41can be instantaneously grasped.

Next, the sensing method of abnormality in the light receiving part42will be explained. Examples of abnormality that will occur in the light receiving part42include a defect of each CCD, wire breakage of any cable between the control part5and the light receiving part42and the like. The method will be explained referring also toFIG. 25schematically illustrating, similarly toFIG. 24, the relationship between the pixel number and the amount of received light.

The fork3delivers the wafer W to the module and then moves to the retracted position while holding no wafer W. Also at the time when the fork3moves to the retracted position in this manner, the light source part41applies light to the light receiving part42as in the case of detecting edge positions of the wafer W. Then, the amount of received light is detected, and the detection of the above abnormality is performed on the basis of the detection value. If the light receiving part42has the above abnormality when receiving the light as described above, the amount of received light by the pixel arranged at a position where it is not shielded by the fork3does not have the second value n2 which is supposed to be detected but sometimes varies. For example, when the CCD having abnormality constituting the light receiving part42cannot receive light at all, the pixel composed of the CCD detects a value different from the second value n2, such as the first value n1 or the like as indicated by a dotted line inFIG. 25.

Accordingly, in the case where there is a pixel indicating a detection value that is not the second value n2 or data on the detection value cannot be obtained, the control part5determines that abnormality occurs in the light receiving part42indicating such a detection value, and makes the detection part4including the light receiving part42unusable. Then, the control part5generates an alarm sound and displays a warning on the screen and switches the transfer mode as in the case where abnormality occurs in the light source part41. The detection of the presence or absence of abnormality in the light receiving part42is performed, for example, every time one of the forks3A,3B delivers the wafer W to the module and then moves to the retracted position while holding no wafer W. In this event, the other fork3moves to the delivery position to deliver the wafer W so that the light from the light source part41is not blocked by the wafer W.

According to the above transfer arm30, the center coordinates of the wafer W are calculated using three detection parts4such that the notch N of the wafer W does not overlap with the detection ranges of the detection parts4, and there is a mode of transferring the wafer W to the module on the basis of the center coordinates. Accordingly, even if one of the four detection parts4becomes unusable, the operation of the transfer arm30does not need to be stopped and the user does not need to enter the apparatus, so that the transfer arm30can deliver the wafer W to the appropriate position of the module with high accuracy and a decrease in operating rate of the substrate treatment apparatus composed of the transfer arm30and the already-described modules can be suppressed. When the four detection parts4are usable, the center coordinates of the wafer W are detected using the four detection parts4. Accordingly, the number of times of performing the operation of advancing to detect the center coordinates of the wafer W can be suppressed and a decrease in throughput can be suppressed.

As the light source part41, a light source in which a plurality of LEDs are linearly arranged or a linear light source in which a light guide material is linearly provided on the light emission side of a single LED can be used. Further, as the light receiving part42, a linear image sensor such as a fiber line sensor, a photoelectronic sensor or the like other than a CCD (Charge Coupled Device) line sensor can be used. In short, various light receiving elements such as a CCD, a photoelectronic sensor or the like can be used as the light receiving element of the light receiving part42. Further, the light source part41may be provided on the upper side of the fork3and the light receiving part42may be provided on the lower side of the fork3. Furthermore, four detection parts4can be provided on each of the two forks3A,3B. In this case, a pair of the light source part41and the linear image sensor constituting the detection part4only need to be provided above and below any of the wafers W held by the retracted forks3A,3B intervening therebetween. Four or more detection parts4may be provided.

Subsequently, a coating and developing apparatus to which the transfer arm30, the heating module21and the resist coating module COT are applied will be briefly explained referring toFIG. 26toFIG. 28. The coating and developing apparatus is connected to an exposure apparatus to constitute a resist pattern forming apparatus, andFIG. 26,FIG. 27,FIG. 28are a plan view, a schematic perspective view, and a side view of the resist pattern forming apparatus respectively.

The resist pattern forming apparatus has a carrier block61, a treatment block62, and an interface block63as illustrated inFIG. 26andFIG. 27. Further, on the interface block63side in the resist pattern forming apparatus, an exposure apparatus64is provided. The treatment block62is provided to be adjacent to the carrier block61. The interface block63is provided to be adjacent to the treatment block62on the side opposite to the carrier block61side of the treatment block62. The exposure apparatus64is provided to be adjacent to the interface block63on the side opposite to the treatment block62side of the interface block63.

The carrier block61has carriers71, mounting tables72and a delivery means C. The carriers71are mounted on the mounting tables72. The delivery means C is to take a wafer W out of the carrier71and deliver the wafer W to the treatment block62, and to receive a treated wafer W treated in the treatment block62and return the treated wafer W into the carrier71.

The treatment block62has, as illustrated inFIG. 26andFIG. 27, a shelf unit U1, a shelf unit U2, a first block (DEV floor) B1, a second block (BCT floor) B2, a third block (COT floor) B3, and a fourth block (TCT floor) B4. The first block (DEV floor) B1is to perform a developing treatment. The second block (BCT floor) B2is to perform a forming treatment of an anti-reflection film to be formed on the lower layer side of a resist film. The third block (COT floor) B3is to perform a coating treatment of a resist solution. The fourth block (TCT floor) B4is to perform a forming treatment of an anti-reflection film to be formed on the upper layer side of the resist film.FIG. 26and the already describedFIG. 1illustrate the third block COT floor B3.

The shelf unit U1is composed of various modules stacked. The shelf unit U1has, for example, delivery modules TRS1, TRS1, CPL11, CPL2, BF2, CPL3, BF3, CPL4, TRS4stacked in order from the bottom as illustrated inFIG. 28. Further, a delivery arm D movable up and down is provided near the shelf unit U1as illustrated inFIG. 26. Between the modules in the shelf unit U1, the wafer W is transferred by the delivery arm D.

The shelf unit U2is composed of various modules stacked. The shelf unit U2has, for example, delivery modules TRS6, TRS6, CPL12stacked in order from the bottom as illustrated inFIG. 28. Note that, inFIG. 28, the delivery module labeled with CPL also serves as a cooling module for temperature regulation, and the delivery module labeled with BF also serves as a buffer module capable of mounting a plurality of wafers W therein.

Between the first block (DEV floor) B1and the second block (BCT floor) B2, a shuttle SH is provided which directly transfers the wafer W from the shelf unit U1to the shelf unit U2.

Each of the second block (BCT floor) B2, the third block (COT floor) B3, and the fourth block (TCT floor) B4has a coating module of a chemical, a heating module group and the already-described transfer arm30. The second block (BCT floor) B2to the fourth block (TCT floor) B4have the same configuration except that the chemical in the second block (BCT floor) B2and the fourth block (TCT floor) B4is a chemical for anti-reflection film and the chemical in the third block (COT floor) B3is a resist solution. The first block (DEV floor) B1has the same configuration as those of the other unit blocks except that a supply module of a developing solution is provided in place of the coating module of a chemical. For convenience of illustration, the transfer arms30in the unit blocks are indicated as A1, A2, A3, A4.

The interface block63has an interface arm F as illustrated inFIG. 28. The interface arm F is provided near the shelf unit U2in the treatment block62. Between the treatment modules in the shelf unit U2and between the shelf unit U2and the exposure apparatus64, the wafer W is transferred by the interface arm F.

The wafers W from the carrier block61are transferred in sequence to one delivery module in the shelf unit U1, for example, the delivery module CPL2corresponding to the second block (BCT floor) B2by the delivery means C. The wafer W transferred to the delivery module CPL2is delivered to the transfer arm A2in the second block (BCT floor) B2, transferred to each of the treatment modules (the coating module and each of the treatment modules in the treatment module group of the heating and cooling system) via the transfer arm A2and subjected to treatment in each of the treatment modules. Thus, an anti-reflection film is formed on the wafer W.

The wafer W on which the anti-reflection film has been formed is delivered to the transfer arm A3in the third block (COT floor) B3via the transfer arm A2, the delivery module BF2in the shelf unit U1, the delivery arm D, and the delivery module CPL3in the shelf unit U1. Then, the wafer W is transferred to each of the treatment modules (the coating module and each of the treatment modules in the treatment module group of the heating and cooling system) via the transfer arm A3and subjected to treatment in each of the treatment modules. Thus, a resist film is formed on the wafer W.

The wafer W on which the resist film has been formed is delivered to the delivery module BF3in the shelf unit U1via the transfer arm A3. Note that the wafer W on which the resist film has been formed may further have an anti-reflection film formed in the fourth block (TCT floor) B4. In this case, the wafer W is delivered to the transfer arm A4in the fourth block (TCT floor) B4via the delivery module CPL4and transferred to each of the treatment modules (the coating module and each of the treatment modules in the treatment module group of the heating and cooling system) via the transfer arm A4and subjected to treatment in each of the treatment modules. Thus, an anti-reflection film is formed on the wafer W. The wafer W on which the anti-reflection film has been formed is then delivered to the delivery module TRS4in the shelf unit U1via the delivery arm A4.

The wafer W on which the resist film has been formed or the wafer W on which the anti-reflection film has been formed on the resist film is mounted on the delivery module CPL11via the delivery arm D, the delivery module BF3or TRS4, delivered to the shuttle SH, directly transferred to the delivery module CPL12in the shelf unit U2, and then delivered to the interface arm F in the interface block63. The wafer W delivered to the interface arm F is transferred to the exposure apparatus64and subjected to predetermined exposure processing. The wafer W is then mounted on the delivery module TRS6in the shelf unit U2via the interface arm F, and returned into the treatment block62. The wafer W returned to the treatment block62is subjected to a developing treatment in the first block (DEV floor) B1. The wafer W subjected to the developing treatment is returned to the carrier71via the transfer arm A1, the delivery module TRS1in the shelf unit U1, and the delivery means C.

Though an example of the transfer by the transfer arm30from the resist coating module COT to the heating module21has been explained in the already-described example, each of the delivery means C, the delivery arm D, and the interface arm F other than the transfer arm30also corresponds to the substrate transfer apparatus in the present invention, and has the aforementioned substrate edge position detection mechanism40as with the transfer arm30. In these substrate transfer apparatuses, the calculation of the center coordinates of the wafer W as explained for the transfer arm30is performed when transferring the wafer W from a module at the preceding stage to a module at the subsequent stage, and transfer is performed on the basis of the center coordinates, in short, in the transfer path, all the transfer from the module at the preceding stage to the module at the subsequent stage is performed as has been explained in the transfer example from the resist coating module COT to the heating module21.

Incidentally, the detection parts4are not limited to be provided on the base31as explained above. As illustrated inFIG. 29,FIG. 30, the light source parts41and the light receiving parts42are arranged on the ceiling side and the floor side of the transfer path20so that the detection of the center position of the wafer W and the decision of the delivery position of the fork3may be performed when the base31and the fork3pass between them. The base31is formed in a shape not blocking the light from the light source parts41. In addition, the base31is slightly moved in the Y-direction as illustrated inFIG. 31instead of slightly displacing the fork3in the X-direction with respect to the detection parts4, to displace the position of the wafer W with respect to the notch N for the detection of the center position.

Further, the above-described detection of the center position of the wafer W only needs to be performed during the transfer from the module at the preceding stage from which the wafer W is received to the module at the subsequent stage to which the wafer is delivered. Accordingly, the detection may be performed with the base31stopped after the fork3retracts or may be performed with the fork3advancing during movement of the base31to the module at the subsequent stage. Though the detection operation of the notch N is performed by advancing the fork3from the reference position that is the retracted position thereof, the detection operation of the notch N may be performed by retracting the fork3from a reference position that is the front side of the retracted position. It is also possible to provide a drive mechanism so that the detection parts4can move with respect to the base31, and move the detection parts4instead of the fork3and detect the center position of the wafer W. Note that in the case where the center position o′ is detected in the temporary mode; the fork3may be moved for acquisition to a position different from the position where the center position o′ is acquired in the normal mode. In other words, the fork may be moved for detection to a position displaced respectively from the retracted position and the first slightly advanced position.

Further, five or more detection parts4may be provided so that the normal mode is performed using the detection parts4, whereas the above-described temporary mode may be executed when the number of usable detection parts4becomes three.

Though whether or not the detection range of the detection part4overlaps with the notch N is determined on the basis of the presence or absence of positional change in the Y-direction of the center coordinates at Steps S6, T4in the above example, another determination method will be explained. Each coordinates o′ acquired at the first slightly advanced position are displaced to the rear side of the fork3by the amount of movement of the fork3from the retracted position. The distance between each coordinates o′ acquired as explained above and each coordinates o′ acquired at the retracted position is calculated. More specifically, the movement amount (displacement amount) of each coordinates o′ after subtracting therefrom the movement amount of the fork3at each coordinates o′ between the retracted position and the first slightly advanced position as illustrated at the lower section ofFIG. 16is calculated. This movement amount is {(X″−X′)2+(Y″−Y′)2}1/2where the X-coordinate and the Y-coordinate of o′ displaced from the first slightly advanced position as described above are X″ and Y″, the X-coordinate and the Y-coordinate at the retracted position are X′ and Y′. o′ that is calculated using the sensor whose detection range does not overlap with the notch N as illustrated inFIG. 16is smaller in movement amount than the other o′.

Hence, at Steps S5, S6in the normal mode, o′ with the radius falling within the normal range and the minimum movement amount can be regarded the correct center position. At Step T4in the temporary mode, it can be determined that the detection range does not overlap with the notch N when the movement amount falls within a preset allowable range and each calculated radius falls within the normal range. When the movement amount does not fall within the allowable range, the fork3A is moved to the second slightly advanced position to acquire the center coordinates as in the case where the difference in the Y component does not fall within the allowable range.