Substrate treating apparatus with inter-unit buffers

The invention provides coating units, heat-treating units, and a first main transport mechanism for transporting substrates to each of these treating units. The substrates are transferred from the first main transport mechanism to a second main transport mechanism through a receiver. When a substrate cannot be placed on the receiver, this substrate is placed on a buffer. Thus, the first main transport mechanism can continue transporting other substrates. The other substrates in the treating units are transported between the treating units without delay, to receive a series of treatments including coating treatment and heat treatment as scheduled. This prevents lowering of the quality of treatment for forming film on the substrates.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No. JP2007-310676, filed on Nov. 30, 2007, the entire disclosure of which is hereby incorporated by reference its entirety for all purposes.

BACKGROUND OF THE INVENTION

This invention relates to a substrate treating apparatus for performing a series of treatments of substrates such as semiconductor wafers, glass substrates for liquid crystal displays, glass substrates for photomasks, and substrates for optical disks (hereinafter called simply “substrates”).

Conventionally, this type of substrate treating apparatus is used to form a resist film on substrates, and develop the substrates exposed in a separate exposing machine. The apparatus includes a treating section having arranged therein at least a coating block for forming film such as resist film, a developing block for developing the substrates, and. Each treating block includes a single main transport mechanism and various treating units. The treating units of the coating block include coating units for applying treating solutions to the substrates, and heat-treating units for heat-treating the substrates. The main transport mechanism of each block, while transporting substrates to the treating units in that block, transfers the substrates through receivers to and from the main transport mechanism of another adjacent treating block, to carry out a series of treatments of the substrates (as disclosed in Japanese Unexamined Patent Publication No. 2003-324139, for example).

The conventional apparatus with such a construction has the following drawbacks.

In the conventional apparatus, when the main transport mechanism of the coating block transfers a substrate to the other adjacent main transport mechanism, the substrate cannot be placed on a receiver if, for example, a different substrate is present on that receiver. In such a case, the main transport mechanism of the coating block stands by until the receiver becomes capable of receiving the substrate. While the main transport mechanism of the coating block is on standby, the main transport mechanism does not transport substrates between the treating units of the coating block. For example, even when a substrate has been treated in a coating unit, this substrate is not transported to another treating unit such as a heat-treating unit. Therefore, the coating block cannot carry out a series of treatments including coating treatment and heat treatment in a predetermined time. As a result, there is an inconvenience of lowering the quality of treatment of the substrates.

SUMMARY OF THE INVENTION

This invention has been made having regard to the state of the art noted above, and its object is to provide a substrate treating apparatus that can prevent lowering the quality of treatment for forming film on substrates.

The above object is fulfilled, according to one embodiment of this invention, by a substrate treating apparatus comprising a film forming section for forming film on substrates, including coating units for applying a treating solution to the substrates, and heat-treating units for heat-treating the substrates; a first main transport mechanism for transporting the substrates to and from the coating units and the heat-treating units; a receiver for receiving the substrates in order to transfer the substrates having the film formed thereon in the film forming section from the first main transport mechanism to a different main transport mechanism; and a buffer disposed adjacent the receiver for temporarily holding the substrates.

According to this embodiment, since the buffer is provided adjacent to the receiver, even when the first main transport mechanism cannot place a substrate on the receiver, the first main transport mechanism can place that substrate on the buffer. Thus, the first main transport mechanism can continue transporting substrates. That is, other substrates can be transported to the coating units and heat-treating units without delay. The film forming section can carry out a series of treatments including coating treatment in the coating units and heat treatment in the heat-treating units for a plurality of substrates on time (as scheduled). This can prevent lowering of the quality of treatment to form film on the substrates.

In the embodiment noted above, the first main transport mechanism may be arranged to place the substrates temporarily on the buffer when the first main transport mechanism cannot place the substrates on the receiver. The first main transport mechanism places the substrates on the buffer when unable to place the substrates on the receiver, to be able to start other substrate transporting operations promptly. Thus, the treatment in progress in the film forming section can be continued on time (as scheduled). This can prevent lowering of the quality of treatment to form film on the substrates.

In the embodiment noted above, the different main transport mechanism may be permitted to receive the substrates placed on the buffer. Then, the substrates can be transported efficiently since this arrangement does not require the first main transport mechanism to transport the substrates from the buffer to the receiver in order to transfer the substrates placed on the buffer to the different main transport mechanism.

In the embodiment noted above, the different main transport mechanism may be permitted to place the substrates on the receiver in order to transfer the substrates to the first main transport mechanism, and also permitted to place the substrates temporarily on the buffer. Then, the substrates can also be transferred from the different main transport mechanism to the first main transport mechanism through the receiver, and in addition the different main transport mechanism also can place the substrates temporarily on the buffer. No delay will occur in the substrate transport by the different main transport mechanism even when the different main transport mechanism cannot place the substrates on the receiver for transferring the substrates from the different main transport mechanism to the first main transport mechanism. Thus, there is no possibility of adversely affecting the quality of substrate treatment.

The different transport mechanism may be arranged to place the substrates temporarily on the buffer when the different main transport mechanism cannot place the substrates on the receiver. Since the different main transport mechanism places the substrates on the buffer when unable to place the substrates on the receiver, there will occur no delay in the substrate transport by the different main transport mechanism.

The buffer may be stacked with the receiver. Then, the first main transport mechanism can selectively access both the receiver and buffer only by moving vertically.

In the embodiment noted above, the buffer may be disposed in at least one of positions over and under the receiver. Then, the first main transport mechanism can selectively access both the receiver and buffer only by moving up and down.

In the embodiment noted above, the buffer may be arranged to accommodate the substrates corresponding in number at least to the number of substrates that can be treated simultaneously in the film forming section. Then, all the substrates that can be treated simultaneously in the film forming section can be placed temporarily on the buffer. Therefore, at whatever time it may become impossible to place the substrates on the receiver, the first main transport mechanism can smoothly transport all the substrates being treated in the film forming section at that time. The series of treatments in the film forming section can be completed for each substrate as usual. Thus, even when it becomes impossible to place the substrates on the receiver while the film forming section is treating the substrates, there is no possibility of lowering the quality of ongoing treatment of the substrates.

The buffer may be arranged to accommodate the substrates corresponding in number at least to the number of coating units. Even when the first main transport mechanism becomes unable to place the substrates on the receiver while the substrates are being treated in the coating units, the first main transport mechanism can transport, at predetermined times, all the substrates being treated in the coating units. Thus, even when it becomes impossible to place the substrates on the receiver while the coating units are treating the substrates, there is no possibility of lowering the quality of ongoing treatment of the substrates.

In the embodiment noted above, the film forming section may be arranged to form resist film on the substrates. Then, resist film can be formed on the substrates with high quality.

The film forming section is arranged to form also anti-reflection film on the substrates. Then, anti-reflection film can be formed on the substrates with high quality.

In another aspect of the embodiment, a substrate treating apparatus comprises a film forming section for forming film on substrates, including coating units for applying a treating solution to the substrates and heat-treating units for heat-treating the substrates; a first main transport mechanism for transporting the substrates to and from the coating units and the heat-treating units; a receiver for receiving the substrates in order to transfer the substrates from the first main transport mechanism to a different main transport mechanism; a buffer disposed adjacent the receiver for temporarily holding the substrates; and a controller for controlling the first main transport mechanism to place on the receiver the substrates to be transferred to the other main transport mechanism, and to place the substrates temporarily on the buffer at an abnormal time when the substrates cannot be placed on the receiver.

According to this embodiment, the first main transport mechanism transports the substrates to and from the coating units and the heat-treating units. The coating units apply a treating solution to the substrates, and the heat-treating units heat-treat the substrates. As a result, film is formed on the substrates. When the substrates can be placed on the receiver, the first main transport mechanism places the substrates with film formed thereon on the receiver to transfer the substrates to the different main transport mechanism. At an abnormal time when the substrates cannot be placed on the receiver, the first main transport mechanism places the substrates temporarily on the buffer. The controller controls the substrate transport of the first main transport mechanism to the receiver and the buffer. Therefore, whether an abnormal time or not, there occurs no delay in the substrate transport by the first main transport mechanism. The treatments in the coating units and heat-treating units can be carried out for the substrates on time (as scheduled). This can prevent lowering of the quality of treatment to form film on the substrates.

In the embodiment noted above, the apparatus may further comprise a first detector for detecting the substrates placed on the receiver; wherein the controller is arranged to cause the substrates to be placed temporarily on the buffer when, in transferring the substrates from the first main transport mechanism to the different main transport mechanism, the controller determines from a result of detection by the first detector that one of the substrates is present on the receiver. With the first detector provided, the controller can reliably determine whether or not this is an abnormal time when the substrates cannot be placed on the receiver.

In the embodiment noted above, the controller may be arranged, when causing the first main transport mechanism to place the substrates temporarily on the buffer, to cause the different main transport mechanism to receive the substrates placed on the buffer. Then, the substrates can be transported efficiently since this arrangement does not require the first main transport mechanism to transport the substrates from the buffer to the receiver in order to transfer the substrates placed on the buffer to the different main transport mechanism.

In a further aspect of the embodiment, a substrate treating apparatus comprises a resist film coating block including resist film coating units for applying a resist film material to substrates and heat-treating units for heat-treating the substrates; a first main transport mechanism transporting the substrates to and from the resist film coating units and the heat-treating units; a developing block disposed adjacent the resist film coating blocks, the developing block including developing units for supplying a developer to the substrates and heat-treating units for heat-treating the substrates; a second main transport mechanism for transporting the substrates to and from the developing units and the heat-treating units; and an interface section disposed adjacent the developing block, and including an interface transport mechanism for transporting the substrates to and from an exposing machine provided separately from the apparatus; wherein the first main transport mechanism and the second main transport mechanism transfer the substrates through a first receiver arranged to receive the substrates, and the first main transport mechanism is arranged, when unable to place the substrates on the first receiver, to place the substrates temporarily on a first buffer.

According to this embodiment, in the resist film coating block, the first main transport mechanism transports the substrates to and from the resist film coating units and the heat-treating units, and each treating unit carries out a predetermined treatment of the substrates. As a result, resist film is formed on the substrates. The first main transport mechanism transfers the substrates with resist film formed thereon to the second main transport mechanism of the developing block. The substrates transported to the developing block are further transported through the interface section to the exposing machine to be exposed therein. The exposed substrates are transported through the interface section to the developing block. In the developing block, the second main transport mechanism transports the substrates to the developing units and heat-treating units, and each treating unit carries out a predetermined treatment for the substrates. As a result, the substrates are developed. The second main transport mechanism transfers the developed substrates to the first main transport mechanism.

The first main transport mechanism and second main transport mechanism transfer the substrates between the transport mechanisms through the first receiver. When a substrate cannot be placed on the first receiver, the first main transport mechanism places the substrate temporarily on the first buffer. Thus, the first main transport mechanism can transport other substrates to and from the resist film coating units and the heat-treating units without delay. The treatments in the resist film coating units and heat-treating units can be carried out for the substrates on time (as scheduled). This can prevent lowering of the quality of treatment in the resist film coating block.

In the embodiment noted above, the first buffer may be disposed adjacent and above or below the first receiver. Then, the first main transport mechanism can selectively access both the receiver and buffer only by moving vertically.

In the embodiment noted above, each of the resist film coating block and the developing block may be divided into stories arranged vertically. The resist film coating units, the first main transport mechanism, and the heat-treating units of the resist film coating block may be arranged on each story of the resist film coating block; the developing units, the second main transport mechanism and the heat-treating units of the developing block may be arranged on each story of the developing block; the first receiver may be provided for each story between the resist film coating block and the developing block; and the first buffer may be provided for each first receiver. A series of treatments is carried out for the substrates in parallel on each story of the resist film coating block, and a series of treatments is carried out for the substrates in parallel on each story of the developing block. This can increase throughput of the substrate treating apparatus. The stories are arranged one over the other to form a layered structure with pluralities of first and second main transport mechanisms and various treating units arranged vertically, which can avoid an enlarged installation area of the substrate treating apparatus.

In the embodiment noted above, the interface transport mechanism may be arranged to transport the substrates to the heat-treating units of the developing block where the heat-treating units carry out post-exposure baking (PEB) treatment of the substrates exposed; the interface transport mechanism and the second main transport mechanism may transfer the substrates through a second receiver for receiving the substrates; and the interface transport mechanism may be arranged, when unable to place the substrates on the second receiver, to place the substrates temporarily on a second buffer. The interface transport mechanism receives the substrates from the exposing machine and transports the substrates to the heat-treating units of the developing block. The heat-treating units of the developing block carry out post-exposure baking (PEB) treatment for the substrates. After the post-exposure baking (PEB) treatment, the interface transport mechanism transports the substrates from the heat-treating units of the developing block to the developing block.

The interface transport mechanism and the second main transport mechanism of the developing block transfer the substrates between the transport mechanisms through the second receiver. When a substrate cannot be placed on the second receiver, the interface transport mechanism places the substrate temporarily on the second buffer. Thus, the interface transport mechanism can promptly start transporting other substrates. Specifically, the interface transport mechanism can unload the substrates having undergone the post-exposure baking (PEB) treatment from the heat-treating units of the developing block on time (as scheduled). This can prevent lowering of the quality of post-exposure baking (PEB) treatment given to the substrates.

In the embodiment noted above, the second buffer may be provided in the interface section. Then, the interface transport mechanism can access the second buffer easily.

In the embodiment noted above, the resist film coating block may further include anti-reflection film coating units for applying a treating solution for anti-reflection film to the substrates. Then, anti-reflection film can be formed on the substrates with high quality.

This specification discloses embodiments directed to the following substrate treating apparatus:

(1) The substrate treating apparatus according to one embodiment, wherein the buffer is arranged to receive the substrates to be transferred from the first main transport mechanism to the different main transport mechanism.

According to the apparatus defined in (1) above, the first main transport mechanism can place on the buffer the substrates with film formed thereon in the film forming section.

(2) The substrate treating apparatus according to one embodiment, wherein the buffer is arranged to receive the substrates placed by the first main transport mechanism.

According to the embodiment defined in (2) above, the first main transport mechanism can place on the buffer the substrates with film formed thereon in the film forming section.

(3) The substrate treating apparatus according to one embodiment, wherein the buffer is disposed between the first main transport mechanism and the different main transport mechanism.

According to the embodiment defined in (3) above, the first main transport mechanism and the different main transport mechanism can transfer the substrates conveniently.

(4) The substrate treating apparatus according to one embodiment, wherein the buffer is juxtaposed with the receiver.

According to the embodiment defined in (4) above, the first main transport mechanism can easily access both the receiver and the buffer.

(5) The substrate treating apparatus according to one embodiment, wherein the coating units include resist film coating units for applying a resist film material.

According to the embodiment defined in (5) above, resist film can be formed on the substrates with high quality.

(6) An embodiment of a substrate treating apparatus according to (5) above, wherein the coating units include anti-reflection film coating units for applying a treating solution for anti-reflection film.

According to the embodiment defined in (6) above, anti-reflection film can be formed on the substrates with high quality.

(7) The substrate treating apparatus according to one embodiment, further comprising a second detector for detecting the substrates placed on the buffer; wherein the controller is arranged to determine from a result of detection by the second detector that one of the substrates is present on the buffer.

According to the embodiment defined in (7) above, with the second detector provided, the controller can reliably determine whether or not a substrate is present on the buffer.

(8) The substrate treating apparatus according to one embodiment, further comprising an anti-reflection film coating block disposed adjacent the resist film coating block, and including anti-reflection film coating units for applying a treating solution for anti-reflection film to the substrates, heat-treating units for heat-treating the substrates, and a third main transport mechanism for transporting the substrates to and from the anti-reflection film coating units and the heat-treating units; wherein the third main transport mechanism and the first main transport mechanism transfer the substrates through a third receiver arranged to receive the substrates, and the third main transport mechanism is arranged, when unable to place the substrates on the third receiver, to place the substrates temporarily on a third buffer.

According to the embodiment defined in (8) above, in the anti-reflection film coating block the third main transport mechanism transports the substrates to and from the anti-reflection film coating units and the heat-treating units, and each treating unit carries out a predetermined treatment of the substrates. As a result, anti-reflection film is formed on the substrates. The third main transport mechanism transfers the substrates with anti-reflection film formed thereon to the first main transport mechanism of the resist film coating block.

The third main transport mechanism and first main transport mechanism transfer the substrates between the transport mechanisms through the third receiver. When a substrate cannot be placed on the third receiver, the third main transport mechanism places the substrate temporarily on the third buffer. Thus, a series of treatments in the anti-reflection film coating block including coating treatment and heat treatment can be carried out for the substrates on time. This can prevent lowering of the quality of treatment for forming anti-reflection film on the substrates.

(9) An embodiment of the substrate treating apparatus according to (8) above, wherein the third buffer is disposed adjacent and above or below the third receiver.

According to the embodiment defined in (9) above, the third main transport mechanism can selectively access both the receiver and buffer only by moving vertically.

(10) An embodiment of a substrate treating apparatus comprising resist film coating units for applying a resist film material to substrates, heat-treating units for heat-treating the substrates, a first main transport mechanism for transporting the substrates to and from the resist film coating units and the heat-treating units, a developing section for developing the substrates, a second main transport mechanism for transporting the substrates to and from the developing section, and transferring the substrates to and from the first main transport mechanism; and a buffer for temporarily holding the substrates, the buffer being disposed adjacent a receiver used for transferring the substrates from the first main transport mechanism to the second main transport mechanism.

According to the embodiment defined in (10) above, since the buffer is provided adjacent to the receiver, even when the first main transport mechanism cannot place a substrate on the receiver, the first main transport mechanism can place that substrate on the buffer. Thus, the first main transport mechanism can continue transporting substrates. That is, other substrates can be transported to the coating units and heat-treating units without delay. A series of treatments in these coating units and heat-treating units is carried out for the substrates on time. This can prevent lowering of the quality of treatment to form film on the substrates.

(11) An embodiment of the substrate treating apparatus according to (10) above, wherein the first main transport mechanism is arranged to place the substrates temporarily on the buffer at an abnormal time when the first main transport mechanism cannot place the substrates on the receiver.

According to the embodiment defined in (11) above, even at an abnormal time, the treatments in the coating units and heat-treating units can be carried out for the substrates on time (as scheduled).

(12) The substrate treating embodiment according to (10) or (11) above, wherein the buffer is arranged to hold a substrate to be accessible to the second main transport mechanism, the second main transport mechanism being permitted to receive the substrate placed on the buffer.

According to the embodiment defined in (12) above, high transporting efficiency is assured since this arrangement does not require the first main transport mechanism to transport the substrates from the buffer to the receiver in order to transfer the substrates placed on the buffer to the second main transport mechanism.

(13) The substrate treating embodiment according to any one of (10) to (12) above, wherein the second main transport mechanism is permitted to place the substrates on the receiver in order to transfer the substrates to the first main transport mechanism, and also permitted to place the substrates temporarily on the buffer.

According to the embodiment defined in (13) above, the substrates can also be transferred from the second main transport mechanism to the first main transport mechanism through the receiver, and in addition the second main transport mechanism also can place the substrates temporarily on the buffer. Even when the second main transport mechanism cannot place a substrate on the receiver, the second main transport mechanism can start transferring other substrates promptly by placing the above substrate on the buffer. Thus, there is no possibility of lowering the quality of treatment of the substrates in the developing section.

(14) The substrate treating embodiment according to (13) above, wherein the second transport mechanism is arranged to place the substrates temporarily on the buffer at an abnormal time when the second main transport mechanism cannot place the substrates on the receiver.

According to the embodiment defined in (14) above, the second transport mechanism places a substrate temporarily on the buffer when the second main transport mechanism cannot place the substrate on the receiver. Thus, the second transport mechanism can transfer other substrates without delay.

(15) The substrate treating embodiment according to any one of (10) to (14) above, wherein the buffer is arranged to accommodate the substrates corresponding in number at least to the number of coating units.

According to the embodiment defined in (15) above, at whatever time it may become impossible to place the substrates on the receiver, all the substrates being treated in the coating units at that time can receive a series of treatments on time.

(16) The substrate treating embodiment according to (15) above, wherein the buffer is arranged to accommodate the substrates corresponding in number at least to a total of the number of coating units and the number of substrates that can be treated simultaneously in the developing section.

According to the embodiment defined in (16) above, at whatever time it may become impossible to place the substrates on the receiver, all the substrates being treated in the developing section at that time can receive a series of treatments on time.

DETAILED DESCRIPTION OF THE INVENTION

One embodiment of this invention will be described in detail hereinafter with reference to the drawings.

FIG. 1is a plan view showing an outline of a substrate treating apparatus according to this embodiment.FIGS. 2 and 3are schematic side views showing an arrangement of treating units included in the substrate treating apparatus.FIGS. 4 through 7are views in vertical section taken on lines a-a, b-b, c-c and d-d ofFIG. 1, respectively.

This embodiment provides a substrate treating apparatus for forming resist film or the like on substrates (e.g. semiconductor wafers) W, and developing exposed wafers W. This apparatus is divided into an indexer section (hereinafter called “ID section”)1, a treating section3and an interface section (hereinafter called “IF section”)5. The ID section1, treating section3and IF section5are arranged adjacent one another in the stated order. An exposing machine EXP, which is an external apparatus separate from this apparatus, is disposed adjacent the IF section5.

The ID section1takes wafers W out of each cassette C, which stores a plurality of wafers W, and deposits wafers W in the cassette C. The ID section1has a cassette table9for receiving cassettes C, and an ID transport mechanism TIDfor transporting wafers W to and from each cassette C.

The treating section3carries out treatment for forming film on the wafers W and treatment for developing the wafers W. The treating section3has a layered structure with a plurality of stories. In this embodiment, the treating section3is divided into two, upper and lower, stories. The upper and lower stories have substantially the same structure as described hereinafter. Each story includes a substrate treatment line for treating wafers W while transporting the wafers W between the ID section1and IF section5. The treatment carried out on each story includes treatment for forming film on the wafers W and treatment for developing the wafers W.FIG. 1shows the upper story.

The treating section3has coating units31and heat-treating units41arranged on each story. The coating units31apply a treating solution to the wafers W. The heat-treating units41heat-treat the wafers W. The coating units31and heat-treating units41constitute a film forming section for forming film on the wafers W. The treating section3has also developing units DEV for supplying a developer to the wafers W, and heat-treating units42for heat-treating the wafers W (to be described hereinafter).

The treating section3includes four main transport mechanisms T1, T2, T3and T4. The main transport mechanisms T1and T2are arranged on the upper story, while the main transport mechanisms T3and T4are arranged on the lower story. Each of the main transport mechanisms T1and T2transports wafers W to and from the coating units31and heat-treating units41. Each of the main transport mechanisms T3and T4transports wafers W to and from the developing units DEV and so on. Further, the main transport mechanisms T1and T2transfer wafers W between the transport mechanisms. Similarly, the main transport mechanisms T3and T4transfer wafers W between the transport mechanisms. Each of the main transport mechanisms T1and T3transfers wafers W to and from the ID transport mechanism TID.

The IF section5transports wafers W to and from the exposing machine EXP provided separately from the apparatus. The IF section5has IF transport mechanisms TIFfor transporting wafers W. The IF transport mechanisms TIFinclude an IF first transport mechanism TIFAand an IF second transport mechanism TIFB. The IF transport mechanisms TIF(first transport mechanism TIFAand second transport mechanism TIFB) correspond to the interface transport mechanisms in this embodiment.

The construction of each component of this embodiment will be described in greater detail hereinafter.

The ID section1takes wafers W out of each cassette C, which stores a plurality of wafers W, and deposits wafers W in the cassette C. The ID section1has a cassette table9for receiving cassettes C. The cassette table9can receive four cassettes C as arranged in a row. The ID section1has also an ID transport mechanism TID. The ID transport mechanism TIDtransports wafers W to and from each cassette C, and transports wafers W to and from receivers PASS1and PASS3to be described hereinafter. The ID transport mechanism TIDhas a movable base21for moving horizontally alongside the cassette table9in the direction of arrangement of the cassettes C, a lift shaft23vertically extendible and contractible relative to the movable base21, and a holding arm25swivelable on the lift shaft23, and extendible and retractable radially of the swivel motion, for holding a wafer W. The ID transport mechanism TIDcorresponds to the indexer transport mechanism in this invention.

In this embodiment, the treating section3includes a plurality of (two) treating blocks Ba and Bb arranged side by side (in substantially the same direction as the transport direction). Each of the treating blocks Ba and Bb is vertically divided into two stories K. The upper story K1of the treating block Ba and the upper story K2of the treating block Bb constitute the upper story of the treating section3noted hereinbefore. Similarly, the lower story K3of the treating block Ba and the lower story K4of the treating block Bb constitute the lower story of the treating section3. The above main transport mechanism T1and various treating units corresponding thereto are arranged on the upper story K1of the treating block Ba, while the main transport mechanism T3and various treating units corresponding thereto are arranged on the lower story K3. Similarly, the main transport mechanism T2and various treating units corresponding thereto are arranged on the upper story K2of the treating block Bb, while the main transport mechanism T4and various treating units corresponding thereto are arranged on the lower story K4.

The treating block Ba is disposed adjacent the ID section1. Receivers PASS1and PASS3for receiving wafers W are provided between the ID section1and the respective stories K1and K3of the treating block Ba. The receiver PASS1receives, as placed thereon, wafers W passed between the ID transport mechanism TIDand the main transport mechanism T1. Similarly, the receiver PASS3receives, as placed thereon, wafers W passed between the ID transport mechanism TIDand the main transport mechanism T3. Seen in a sectional view, the receiver PASS1is disposed at a height adjacent to a lower part of the upper story K2, while the receiver PASS3is disposed at a height adjacent to an upper part of the lower story K3. Thus, the positions of receiver PASS1and receiver PASS3are relatively close to each other for allowing the ID transport mechanism TIDto move between the receiver PASS1and receiver PASS3through using only a small amount of vertical movement.

Receivers PASS2and PASS4for receiving wafers W are provided for the respective stories K between the treating blocks Ba and Bb. Specifically, the receiver PASS2is disposed between the story K1and story K2, and the receiver PASS4between the story K3and story K4. The main transport mechanisms T1and T2transfer wafers W through the receiver PASS2, and the main transport mechanisms T3and T4through the receiver PASS4.

The receiver PASS1includes a plurality of receivers (two in this embodiment). These receivers PASS1are arranged vertically adjacent to each other. Similarly, each of the receivers PASS2-PASS4, and each of receivers PASS5and PASS6to be described hereinafter, includes a plurality of receivers (two in this embodiment) arranged vertically adjacent to each other.

One of the receivers PASS constituting each pair of receivers PASS1-PASS6is selected according to a direction for transferring wafers W.

The receiver PASS1, for example, has two receivers PASS1Aand PASS1Barranged vertically adjacent to each other. One of these receivers PASS1Areceives wafers W passed from the ID transport mechanism TIDto the main transport mechanism T1. The other receiver PASS1Breceives wafers W passed from the main transport mechanism T1to the ID transport mechanism TID.

The receiver PASS2, for example, has two receivers PASS2Aand PASS2Barranged vertically adjacent to each other. One of these receivers PASS2Areceives wafers W passed from the main transport mechanism T1to the main transport mechanism T2. The other receiver PASS2Breceives wafers W passed from the main transport mechanism T2to the main transport mechanism T1. In this case, the wafers W placed on one of the receivers PASS2Aare wafers W having film formed in the film forming section (coating units31and heat-treating units41) on the story K1. The wafers W placed on the other receiver PASS2Bare wafers W developed in the developing units DEV on the story K2. This is the case also with the receiver PASS4.

Each of the receivers PASS1-PASS6has a plurality of support pins projecting therefrom, for receiving a wafer W in a substantially horizontal position on these support pins. Each of the receivers PASS1-PASS6has also a sensor Sp for detecting presence or absence of a wafer W. Detecting signals of each sensor Sp are inputted to a control section90described hereinafter. Based on the detection signals of each sensor Sp, the control section90determines whether or not a wafer W is placed on the receiver PASS, and controls the transport mechanisms in transferring wafers W through the receiver PASS. The receiver PASS2and receiver PASS4correspond to the first receiver in this invention. The sensors Sp for detecting wafers W placed on the receivers PASS2and PASS4correspond to the first detector in this invention.

Further, buffers BF2and BF4are provided for the respective receivers PASS2and PASS4between the treating blocks Ba and Bb. The buffers BF2and BF4are used to hold wafers W temporarily. In this embodiment, when a wafer W cannot be placed on each receiver PASS, the wafer W is placed on the corresponding buffer BF temporarily. That is, usually or during a normal operation, the wafers W are placed only on the receivers PASS, and the wafers W are not placed on the buffers BF.

The buffers BF2and BF4are arranged adjacent the receivers PASS2and PASS4, respectively. In this embodiment, the buffer BF2is stacked under the receiver PASS2, and the buffer BF4under the receiver PASS4.

The number of wafers W that can be accommodated in each of the buffers BF2and BF4, preferably, is equal to or larger than the number of coating units31provided on each story K1or K3. Where, for example, the story K1has two resist film coating units RESIST1and two anti-reflection film coating units BARC1, the buffer BF2can accommodate at least four wafers W which corresponds to the total number of coating units. More preferably, the number of wafers W that can be accommodated in each of the buffers BF2and BF4is equal to or larger than the number of wafers W that can be treated simultaneously in the film forming section on the story K1or K3.

In this embodiment, as shown inFIG. 4, each of the buffers BF2and BF4can accommodate five wafers W.

Each of the buffers BF2and BF4has shelves for storing wafers W in multiple stages, and is open at opposite ends facing the main transport mechanism T1and main transport mechanism T2. Thus, both of the main transport mechanism T1and main transport mechanism T2can deposit wafers W on the shelves, and fetch wafers W from the shelves. The buffers BF2and BF4are not limited to the above construction. As long as they can receive wafers W temporarily, the buffers BF2and BF4may hold wafers W in any positions, e.g. peripheral positions or at the lower surfaces. For example, each buffer BF may have a plurality of projecting support pins like the receivers PASS, for supporting wafers W in a substantially horizontal position.

Each of the buffers BF2and BF4, and buffers BFIF described hereinafter, has a sensor (not shown) for detecting presence or absence of wafers W placed thereon. Detection signals of each sensor is inputted to the control section90described hereinafter. Based on the detection signals of each sensor, the control section90determines whether or not wafers W are placed on the buffer BF, and controls substrate transport of the corresponding transport mechanisms. Each of the buffers BF2and BF4corresponds to the first buffer in this invention. Each sensor for detecting wafers W placed on the buffer BF2or BF4corresponds to the second detector in this invention.

The story K1will now be described. The main transport mechanism T1is movable in a transporting space A1extending substantially through the center of the story K1and parallel to the direction of transport. The treating units on the story K1are divided broadly into coating units31for applying a treating solution to wafers W, and heat-treating units41for heat-treating the wafers W. The coating units31are arranged on one side of the transporting space A1, while the heat-treating units41are arranged on the other side thereof. The coating units31and heat-treating units41constitute the film forming section noted hereinbefore.

The coating units31are arranged vertically and horizontally, each facing the transporting space A1. In this embodiment, four coating units31in total are arranged in two columns and two rows.

The coating units31include anti-reflection film coating units BARC for forming anti-reflection film on the wafers W, and resist film coating units RESIST for forming resist film on the wafers W (i.e. carrying out resist film forming treatment).

The anti-reflection film coating units BARC apply a treating solution for anti-reflection film to the wafers W. The resist film coating units RESIST apply a resist film material to the wafers W. The plurality of (two) anti-reflection film coating units BARC are arranged at substantially the same height in the lower row. The plurality of resist film coating units RESIST are arranged at substantially the same height in the upper row. No dividing wall or partition is provided between the anti-reflection film coating units BARC. That is, all the anti-reflection film coating units BARC are only housed in a common chamber, and the atmosphere around each anti-reflection film coating unit BARC is not blocked off (i.e. is in communication). Similarly, the atmosphere around each resist film coating unit RESIST is not blocked off.

Reference is made toFIGS. 8A and 8B.FIG. 8Ais a plan view of the coating units31.FIG. 8Bis a sectional view of a coating unit31. Each coating unit31includes a spin holder32for holding and spinning a wafer W, a cup33surrounding the wafer W, and a supply device34for supplying a treating solution to the wafer W.

The supply device34includes a plurality of nozzles35, a gripper36for gripping one of the nozzles35, and a nozzle moving mechanism37for moving the gripper36to move one of the nozzles35between a treating position above the wafer W and a standby position away from above the wafer W. Each nozzle35has one end of a treating solution pipe38connected thereto. The treating solution pipe38is arranged movable (flexible) to permit movement of the nozzle35between the standby position and treating position. The other end of each treating solution pipe38is connected to a treating solution source (not shown). Specifically, in the case of anti-reflection film coating units BARC, the treating solution sources supply different types of treating solution for anti-reflection film to the respective nozzles35. In the case of resist film coating units RESIST, the treating solution sources supply different types of resist film material to the respective nozzles35.

The nozzle moving mechanism37has first guide rails37aand a second guide rail37b. The first guide rails37aare arranged parallel to each other and opposed to each other across the two cups33arranged sideways. The second guide rail37bis slidably supported by the two first guide rails37aand disposed above the two cups33. The gripper36is slidably supported by the second guide rail37b. The first guide rails37aand second guide rail37btake guiding action substantially horizontally and in directions substantially perpendicular to each other. The nozzle moving mechanism37further includes drive members (not shown) for sliding the second guide rail37b, and sliding the gripper36. The drive members are operable to move the nozzle35gripped by the gripper36to the treating positions above the two spin holders32.

The plurality of heat-treating units41are arranged vertically and horizontally, each facing the transporting space A1. In this embodiment, three heat-treating units41can be arranged horizontally, and five heat-treating units41can be stacked vertically. Each heat-treating unit41has a plate43for receiving a wafer W. The heat-treating units41include cooling units CP for cooling wafers W, heating and cooling units PHP for carrying out heating and cooling treatments continually, and adhesion units AHL for heat-treating wafers W in an atmosphere of hexamethyldisilazane (HMDS) vapor in order to promote adhesion of coating film to the wafers W. As shown inFIG. 5, each heating and cooling unit PHP has two plates43, and a local transport mechanism (not shown) for moving a wafer W between the two plates43. The various types of heat-treating units CP, PHP and AHL are arranged in appropriate positions.

The main transport mechanism T1will be described specifically. Reference is made toFIG. 9.FIG. 9is a perspective view of the main transport mechanism T1. The main transport mechanism T1has two third guide rails51for providing vertical guidance, and a fourth guide rail52for providing horizontal guidance. The third guide rails51are fixed opposite each other at one side of the transporting space A1. In this embodiment, the third guide rails51are arranged at the side adjacent the coating units31. The fourth guide rail52is slidably attached to the third guide rails51. The fourth guide rail52has a base53slidably attached thereto. The base53extends transversely, substantially to the center of the transporting space A1. Further, drive members (not shown) are provided for vertically moving the fourth guide rail52, and horizontally moving the base53. The drive members are operable to move the base53to positions for accessing the coating units31and heat-treating units41arranged vertically and horizontally.

The base53has a turntable55rotatable about a vertical axis Q. The turntable55has two holding arms57aand57bhorizontally movably attached thereto for holding wafers W, respectively. The two holding arms57aand57bare arranged vertically close to each other. Further, drive members (not shown) are provided for rotating the turntable55, and moving the holding arms57aand57b. The drive members are operable to move the turntable55to positions opposed to the coating units31, heat-treating units41, receivers PASS1and PASS2and buffer BF2, and to extend and retract the holding arms57aand57bto and from the coating units31and so on.

The story K3will be described next. Like reference numerals are used to identify like parts which are the same as in the story K1, and will not be described again. The layout (arrangement) in plan view of the main transport mechanism T3and various treating units on the story K3is substantially the same as on the story K1. Thus, the arrangement of the various treating units of the story K3as seen from the main transport mechanism T3is substantially the same as the arrangement of the various treating units of the story K1as seen from the main transport mechanism T1. The coating units31and heat-treating units41of the story K3are stacked under the coating units31and heat-treating units41of the story K1, respectively.

In the following description, when distinguishing the resist film coating units RESIST in the stories K1and K3, subscripts “1” and “3” will be affixed (for example, the resist film coating units RESIST in the story K1will be referred to as “resist film coating units RESIST1”).

The other aspects of the treating block Ba will be described. As shown inFIGS. 5 and 6, each of the transporting spaces A1and A3has a first blowout unit61for blowing out a clean gas, and an exhaust unit62for sucking the gas. Each of the first blowout unit61and exhaust unit62is in the form of a flat box having substantially the same area as the transporting space A1in plan view. Each of the first blowout unit61and exhaust unit62has first blowout openings61aor exhaust openings62aformed in one surface thereof. In this embodiment, the first blowout openings61aor exhaust openings62aare in the form of numerous small bores f (seeFIG. 9). The first blowout units61are arranged over the transporting spaces A1and A3with the first blowout openings61adirected downward. The exhaust units62are arranged under the transporting spaces A1and A3with the exhaust openings62adirected upward. The atmosphere in the transporting space A1and the atmosphere in the transporting space A3are blocked off by the exhaust unit62of the transporting space A1and the first blowout unit61of the transporting space A3. Thus, each of the stories K1and K3has the atmosphere blocked off from the other.

Referring toFIG. 5, the first blowout units61of the transporting spaces A1and A3are connected to a common, first gas supply pipe63. The first gas supply pipe63extends laterally of the receivers PASS2and PASS4from an upper position of the transporting space A1to a lower position of the transporting space A3, and is bent below the transporting space A3to extend horizontally. The other end of the first gas supply pipe63is connected to a gas source not shown. Similarly, the exhaust units62of the transporting spaces A1and A3are connected to a common, first gas exhaust pipe64. The first gas exhaust pipe64extends laterally of the receivers PASS2and PASS4from a lower position of the transporting space A1to a lower position of the transporting space A3, and is bent below the transporting space A2to extend horizontally. As the gas is blown out of each first blowout opening61aand sucked and exhausted through each exhaust opening62aof the transporting spaces A1and A3, gas currents are formed to flow from top to bottom of the transporting spaces A1and A3, thereby keeping each of the transporting spaces A1and A3in a clean state.

As shown inFIGS. 1,6and8A, each coating unit31of the stories K1and K3has a pit portion PS extending vertically. The pit portion PS accommodates a second gas supply pipe65extending vertically for supplying the clean gas, and a second gas exhaust pipe66extending vertically for exhausting the gas. Each of the second gas supply pipe65and second gas exhaust pipe66branches at a predetermined height in each coating unit31to extend substantially horizontally from the pit portion PS. A plurality of branches of the second gas supply pipe65are connected to second blowout units67for blowing out the gas downward. A plurality of branches of the second gas exhaust pipe66are connected for communication to the bottoms of the respective cups33. The other end of the second gas supply pipe65is connected to the first gas supply pipe63below the story K3. The other end of the second gas exhaust pipe66is connected to the first gas exhaust pipe64below the story K3. As the gas is blown out of the second blowout units67and exhausted through the second exhaust pipes62a, the atmosphere inside each cup33is constantly maintained clean, thereby allowing for excellent treatment of the wafer W held by the spin holder32.

The pit portions PS further accommodate piping of the treating solutions, electric wiring and the like (not shown). Thus, with the pit portions PS accommodating the piping and electric wiring provided for the coating units31of the stories K1and K3, the piping and electric wiring can be reduced in length.

The treating block Ba has one housing75for accommodating the main transport mechanisms T1and T3, coating units31and heat-treating units41described hereinbefore. The treating block Bb described hereinafter also has a housing75for accommodating the main transport mechanisms T2and T4and the various treating units of the treating block Bb. The housing75of the treating block Ba and the housing75of the treating block Bb are separate entities. Thus, with each of the treating blocks Ba and Bb having the housing75accommodating the main transport mechanisms T and various treating units en bloc, the treating section3may be manufactured and assembled simply. The treating block Ba corresponds to the resist film coating block in this invention. The main transport mechanisms T1and T3correspond to the first main transport mechanism in this invention.

The treating block Bb is disposed adjacent the IF section5. The story K2will be described. Like reference numerals are used to identify like parts which are the same as in the story K1and will not be described again. The story K2has a transporting space A2formed as an extension of the transporting space A1.

The treating units on the story K2are developing units DEV for developing wafers W, heat-treating units42for heat-treating the wafers W, and an edge exposing unit EEW for exposing peripheral regions of the wafers W. The developing units DEV are arranged at one side of the transporting space A2, and the heat-treating units42and edge exposing unit EEW are arranged at the other side of the transporting space A2. Preferably, the developing units DEV are arranged at the same side as the coating units31. It is also preferable that the heat-treating units42and edge exposing unit EEW are arranged in the same row as the heat-treating units41. The developing units DEV and heat-treating units42constitute a developing section for developing wafers W.

The number of developing units DEV is four, and sets of two units DEV arranged horizontally along the transporting space A2are stacked one over the other. As shown inFIGS. 1 and 6, each developing unit DEV includes a spin holder77for holding and spinning a wafer W, and a cup79surrounding the wafer W. The two developing units DEV arranged at the lower level are not separated from each other by a partition wall or the like. A supply device81is provided for supplying developers to the two developing units DEV. The supply device81includes two slit nozzles81ahaving a slit or a row of small bores for delivering the developers. The slit or row of small bores, preferably, has a length corresponding to the diameter of wafer W. Preferably, the two slit nozzles81aare arranged to deliver developers of different types or concentrations. The supply device81further includes a moving mechanism81bfor moving each slit nozzle81a. Thus, the slit nozzles81aare movable, respectively, over the two spin holders77juxtaposed sideways.

The plurality of heat-treating units42are arranged sideways along the transporting space A2, and stacked one over the other. The heat-treating units42include heating units HP for heating wafers W, cooling units CP for cooling wafers W, and heating and cooling units PHP for successively carrying out heating treatment and cooling treatment.

The plurality of heating and cooling units PHP are vertically stacked in the column closest to the IF section5, each having one side facing the IF section5. The heating and cooling units PHP on the story K2have transport ports formed in the sides thereof for passage of wafers W. IF transport mechanisms TIFto be described hereinafter transport wafers W through the above transport ports to the heating and cooling units PHP. The heating and cooling units PHP arranged on the story K2carry out post-exposure baking (PEB) treatment for exposed wafers W.

The single edge exposing unit EEW is disposed in a predetermined position. The edge exposing unit EEW includes a spin holder (not shown) for holding and spinning a wafer W, and a light emitter (not shown) for exposing edges of the wafer W held by the spin holder.

The receiver PASS5is formed on top of the heating and cooling units PHP on the story K2. Through the receiver PASS5, the main transport mechanism T2and IF transport mechanisms TIFto be described hereinafter transfer wafers W.

The main transport mechanism T2is disposed substantially centrally of the transporting space A2in plan view. The main transport mechanism T2has the same construction as the main transport mechanism T1. The main transport mechanism T2transports wafers W to and from the receiver PASS2, various heat-treating units42, edge exposing unit EEW and receiver PASS5.

The story K4will be described briefly. The relationship in construction between story K2and story K4is similar to that between stories K1and K3. The treating units U on the story K4are developing units DEV, heat-treating units42and an edge exposing unit EEW. The heat-treating units42on the story K4include heating units HP, cooling units CP and heating and cooling units PHP. The receiver PASS6is formed on top of the heating and cooling units PHP on the story K4. The main transport mechanism T4and IF transport mechanisms TIFdescribed hereinafter transfer wafers W through the receiver PASS6. The heating and cooling units PHP on the story K4also correspond to the PEB units in this invention.

In the following description, when distinguishing the developing units DEV, edge exposing units EEW and so on provided on the stories K2and K4, subscripts “2” and “4” will be affixed (for example, the heating units HP on the story K2will be referred to as “heating units HP2”).

Each of the transporting spaces A2and A4of the stories K2and K4also has constructions corresponding to the first blowout unit61and exhaust unit62. Each developing unit DEV of the stories K2and K4also has constructions corresponding to the second blowout unit67and second gas exhaust pipe66.

The treating block Bb corresponds to the developing block in this invention. Each of the main transport mechanism T2and main transport mechanism T4corresponds to the second main transport mechanism and to the other main transport mechanism in this invention. Each of the receiver PASS5and receiver PASS6corresponds to the second receiver in this invention.

The IF section5transfers wafers W between the treating section3(more particularly, the stories K2and K4of the treating block Bb) and the exposing machine EXP. The IF section5has IF transport mechanisms TIFfor transporting wafers W. IF transport mechanisms TIFinclude an IF first transport mechanism TIFAand an IF second transport mechanism TIFBthat can transfer wafers W to and from the transport mechanisms. IF first transport mechanism TIFAtransports wafers W to and from the stories K2and K4. In this embodiment, as described hereinbefore, IF first transport mechanism TIFAtransports wafers W to and from the receivers PASS5and PASS6on the stories K2and K4, and to and from the heating and cooling units PHP on the stories K2and K4. IF second transport mechanism TIFBtransports wafers W to and from the exposing machine EXP. IF transport mechanisms TIFcorrespond to the interface transport mechanisms in this invention.

As shown inFIG. 1, IF first transport mechanism TIFAand IF second transport mechanism TIFBare arranged in a transverse direction substantially perpendicular to the direction of arrangement of the main transport mechanisms T on each story. IF first transport mechanism TIFAis disposed at the side where the heat-treating units42and so on of the treating block Bb are located. IF second transport mechanism TIFBis disposed at the side where the developing units DEV of the treating block Bb are located.

Stacked in multiples stages between IF first and second transport mechanisms TIFAand TIFBare a receiver PASS-CP for receiving and cooling wafers W, a receiver PASS7for receiving wafers W, and buffers BFIF for temporarily storing wafers W. The buffers BFIF are divided into a send buffer BFIFSfor temporarily storing wafers W to be sent to the exposing machine EXP, and a return buffer BFIFRfor temporarily storing wafers W to be returned to the treating section3. The return buffer BFIFRstores wafers W having received post-exposure baking (PEB) treatment. The send buffer BFIFScan accommodate five wafers W. The return buffer BFIFRcan accommodate eight wafers W which corresponds in number to the total of heating and cooling units PHP which carry out the post-exposure baking (PEB) treatment.

IF first and second transport mechanisms TIFAand TIFBtransfer wafers W through the receiver PASS-CP and receiver PASS7. The buffers BFIF are accessed exclusively by IF first transport mechanism TIFA. The return buffer BFIFRcorresponds to the second buffer in this invention.

As shown inFIG. 7, IF first transport mechanism TIFAincludes a fixed base83, lift shafts85vertically extendible and contractible relative to the base83, and a holding arm87swivelable on the lift shafts85, and extendible and retractable radially of the swivel motion, for holding a wafer W. IF second transport mechanism TIFBalso has a base83, lift shafts85and a holding arm87.

A control system of this apparatus will be described next.FIG. 10is a control block diagram of the substrate treating apparatus according to the invention. As shown, the control section90of this apparatus includes a main controller91and first to seventh controllers93,94,95,96,97,98and99.

The main controller91performs overall control of the first to seventh controllers93-99. Further, the main controller91can communicate through a host computer with an exposing machine controller provided for the exposing machine EXP. The first controller93controls substrate transport by the ID transport mechanism TID. The second controller94controls substrate transport by the main transport mechanism T1, and substrate treatment in the resist film coating units RESIST1, anti-reflection film coating units BARC1, cooling units CP1, heating and cooling units PHP1and adhesion units AHL1. The third controller95controls substrate transport by the main transport mechanism T2, and substrate treatment in the edge exposing unit EEW2, developing units DEV2, heating units HP2and cooling units CP2. The controls by the fourth and fifth controllers96and97correspond to those by the second and third controllers94and95, respectively. The sixth controller98controls substrate transport by IF first transport mechanism TIFA, and substrate treatment in the heating and cooling units PHP2and PHP4. The seventh controller99controls substrate transport by IF second transport mechanism TIFB. The first to seventh controllers93-99carry out the controls independently of one another.

Each of the main controller91and the first to seventh controllers93-99is realized by a central processing unit (CPU) which performs various processes, a RAM (Random Access Memory) used as the workspace for operation processes, and a storage medium such as a fixed disk for storing a variety of information including a predetermined processing recipe (processing program).

Next, operation of the substrate treating apparatus in this embodiment will be described.FIG. 11is a flow chart of a series of treatments of wafers W, indicating the treating units and receivers to which the wafers W are transported in order.FIG. 12is a view schematically showing operations repeated by each transport mechanism, and specifying an order of treating units, receivers and cassettes accessed by the transport mechanisms.FIGS. 11 and 12show an example of ordinary operation in which the transport mechanisms can transfer wafers W through the receivers PASS. The following description will be made separately for each transport mechanism. Further, regarding the main transport mechanisms T1-T4and IF transport mechanisms TIF, an example of operation in which wafers W cannot be placed on the receivers PASS will be described in addition to the example of normal operation.

The ID transport mechanism TIDmoves to a position opposed to one of the cassettes C, holds with the holding arm25a wafer W to be treated and takes the wafer W out of the cassette C. The ID transport mechanism TIDswivels the holding arm25, vertically moves the lift shaft23, moves to a position opposed to the receiver PASS1, and places the wafer W on the receiver PASS1A(which corresponds to step S1ainFIG. 11; only step numbers will be indicated hereinafter). At this time, a wafer W usually is present on the receiver PASS1B, and the ID transport mechanism TIDreceives this wafer W and stores it in a cassette C (step S23). When there is no wafer W on the receiver PASS1B, step S23is omitted. Then, the ID transport mechanism TIDaccesses the cassette C, and transports a wafer W from the cassette C to the receiver PASS3A(step S1b). Here again, if a wafer W is present on the receiver PASS3B, the ID transport mechanism TIDwill store this wafer W in a cassette C (step S23). The ID transport mechanism TIDrepeats the above operation.

This operation of the ID transport mechanism TIDis controlled by the first controller93. As a result, the wafers W in the cassette C are fed to the story K1, and the wafers W delivered from the story K1are stored in the cassette C. Similarly, the wafers W in the cassette C are fed to the story K3, and the wafers W delivered from the story K3are stored in the cassette C.

Since operation of the main transport mechanism T3is substantially the same as operation of the main transport mechanism T1, only the main transport mechanism T1will be described. The main transport mechanism T1moves to a position opposed to the receiver PASS1. At this time, the main transport mechanism T1holds, on one holding arm57(e.g.57b), a wafer W received immediately before from the receiver PASS2B. The main transport mechanism T1places this wafer W on the receiver PASS1B(step S22), and holds the wafer W present on the receiver PASS1Awith the other holding arm57(e.g.57a).

The main transport mechanism T1accesses a predetermined one of the cooling units CP1. There is a different wafer W having already received a predetermined heat treatment (cooling) in the cooling unit CP1. The main transport mechanism T1holds the different wafer W with the unloaded holding arm57(holding no wafer W), takes it out of the cooling unit CP1, and loads into the cooling unit CP1the wafer W having been received from the receiver PASS1A. Then, the main transport mechanism T1, holding the cooled wafer W, moves to one of the anti-reflection film coating units BARC1. The cooling unit CP1starts heat treatment (cooling) of the wafer W loaded therein (step S2). This heat treatment (cooling) will have been finished by the time the main transport mechanism T1accesses this cooling unit CP1next time. The following description assumes that wafers W having received predetermined treatments are present also in the other, different heat-treating units41and coating units31when the main transport mechanism T1makes access thereto.

Accessing the anti-reflection film coating unit BARC1, the main transport mechanism T1takes a wafer W having anti-reflection film formed thereon from the anti-reflection film coating unit BARC1, and places the cooled wafer W on the spin holder32of the anti-reflection film coating unit BARC1. Then, the main transport mechanism T1, holding the wafer W having anti-reflection film formed thereon, moves to one of the heating and cooling units PHP1. The anti-reflection film coating unit BARC1starts treatment of the wafer W placed on the spin holder32(step S3).

Specifically, the spin holder32spins the wafer W in horizontal posture, the gripper26grips one of the nozzles35, the nozzle moving mechanism37moves the gripped nozzle35to a position above the wafer W, and the treating solution for anti-reflection film is supplied from the nozzle35to the wafer W. The treating solution supplied spreads all over the wafer W, and is scattered away from the wafer W. The cup33collects the scattering treating solution. In this way, the treatment is carried out for forming anti-reflection film on the wafer W.

Accessing the heating and cooling unit PHP1, the main transport mechanism T1takes a wafer W having received heat treatment out of the heating and cooling unit PHP1, and loads the wafer W having anti-reflection film formed thereon into the heating and cooling unit PHP1. Then, the main transport mechanism T1, holding the wafer W taken out of the heating and cooling unit PHP1, moves to one of the cooling units CP1. The heating and cooling unit PHP1receives a wafer W successively on the two plates43, to heat the wafer W on one of the plates43and then to cool the wafer W on the other plate43(step S4).

Having moved to the cooling unit CP1, the main transport mechanism T1takes a wafer W out of the cooling unit CP1, and loads the wafer W held by the transport mechanism T1into the cooling unit CP1. The cooling unit CP1cools the wafer W loaded therein (step S5).

Then, the main transport mechanism T1moves to one of the resist film coating units RESIST1. The main transport mechanism T1takes a wafer W having resist film formed thereon from the resist film coating unit RESIST1, and loads the wafer W held by the main transport mechanism T1into the resist film coating unit RESIST1. The resist film coating unit RESIST1supplies the resist film material while spinning the wafer W loaded therein, to form resist film on the wafer W (step S6).

The main transport mechanism T1further moves to one of the heating and cooling units PHP1and one of the cooling units CP1. The main transport mechanism T1loads the wafer W having resist film formed thereon into the heating and cooling unit PHP1, transfers a wafer W treated in the heating and cooling unit PHP1to the cooling unit CP1, and receives a wafer W treated in the cooling unit CP1. The heating and cooling unit PHP1and cooling unit CP1carry out predetermined treatments of newly loaded wafers W, respectively (steps S7and S8).

The main transport mechanism T1moves to the receiver PASS2, places the wafer W it is holding on the receiver PASS2A(step S9), and receives a wafer W present on the receiver PASS2A(step S21).

Subsequently, the main transport mechanism T1accesses the receiver PASS1again, and repeats the above operation. This operation is controlled by the second controller94. As a result, the main transport mechanism T1receives a wafer W from the receiver PASS1and transports the wafer W to a predetermined treating unit (a cooling unit CP1in this embodiment), and takes a treated wafer W from this treating unit. Subsequently, the main transport mechanism T1transports the wafer W taken out to a different treating unit, and takes a treated wafer W from the different treating unit. In this way, the treatment is carried out in parallel for a plurality of wafers W by transferring a treated wafer W from each treating unit to a new treating unit. Starting with a wafer W first placed on the receiver PASS1, the wafers W are successively placed on the receiver PASS2to be fed to the story K2. Similarly, the wafers W are placed on the receiver PASS1in the order of placement on the receiver PASS2, to be fed to the ID section1.

Next, operations taking place when the main transport mechanism T1cannot place the wafer W on the receiver PASS2in the above step S9will be described.

A situation where a wafer W cannot be placed on the receiver PASS2may be caused by the receiver PASS2, e.g. due to a different wafer W present on the receiver PASS2. Apart from this, the cause may lie in a different component such as the main transport mechanism T1, various treating units or controller90. The wafer cannot be placed on the receiver PASS2when the main transport mechanism T1fails to operate properly, when the control section90does not permit the main transport mechanism T1to place the wafer W on the receiver PASS2, or when the control section90fails to control properly. In this specification, a time when a wafer W cannot be placed on a receiver PASS will be called an abnormal time as appropriate.

Whether a wafer W can be placed on the receiver PASS2is determined by the second controller94. The second controller94determines from a result of detection by the sensor Sp of the receiver PASS2whether another wafer W is present on the receiver PASS2. When another wafer W is present on the receiver PASS2, the second controller94determines that the further wafer W cannot be placed on the receiver PASS2. Since the result of detection by the sensor Sp of the receiver PASS2is inputted also to the third controller95, the same determination is made also by the third controller95.

When the second controller94determines that the wafer W cannot be placed on the receiver PASS2in step S9, the main transport mechanism T1moves to the position opposed to the buffer BF2, and temporarily places the wafer W it holds on the buffer BF2. Once the wafer W is placed on the buffer BF2, the operation shifts to the ordinary substrate transporting operation of step S21noted hereinbefore. Specifically, the main transport mechanism T1receives a wafer W from the receiver PASS2B(step S21), and places the received wafer W on the receiver PASS1(step S22).

After further repeating the series of operations, when a wafer W cannot be placed on the receiver PASS2in step S9again, the main transport mechanism T1temporarily places the wafer W on the buffer BF2. The buffer BF2can accommodate five wafers W in this embodiment. Even if the state where wafers W cannot placed on the receiver PASS2continues, the main transport mechanism T1can repeat the series of operations at least five times. This operation of the main transport mechanism T1is also controlled by the second controller94.

Thus, even when a wafer W cannot be placed on the receiver PASS2, the main transport mechanism T1, by placing the wafer W on the buffer BF2, can promptly shift to operation for transporting other wafers W. Therefore, the main transport mechanism T1can continue the transporting operation in steps S21et seq. Since the buffer BF2is disposed adjacent the receiver PASS2, the time taken in the operation for placing a wafer W on the buffer BF2is almost the same as the time taken in the operation (step S9) for placing a wafer W on the receiver PASS2. Therefore, the transporting steps, steps S21et seq., may be resumed after step S9without delay, compared with a schedule for the normal operation (specifically, a schedule for the case where the wafer can be placed on the receiver PASS2).

Since the buffer BF2can accommodate five wafers W, even if it becomes impossible for the main transport mechanism T1to place a wafer W on the receiver PASS2while all of the four coating units31are treating wafers, the wafers W can be transported successively from the coating units31to the heat-treating units41. It is therefore possible to start heat treatment of each wafer W as scheduled for a normal operation. Thus, even when a wafer W cannot be placed on the receiver PASS2, it is possible to prevent lowering the quality of treatment for forming film on the wafers W.

Since operation of the main transport mechanism T4is substantially the same as operation of the main transport mechanism T2, only the main transport mechanism T2will be described. The main transport mechanism T2moves to a position opposed to the receiver PASS2. At this time, the main transport mechanism T2holds a wafer W received from a cooling unit CP2accessed immediately before. The main transport mechanism T2places this wafer W on the receiver PASS2B(step S21), and holds the wafer W present on the receiver PASS2A(step S9).

The main transport mechanism T2accesses the edge exposing unit EEW2. The main transport mechanism T2receives a wafer W having received a predetermined treatment in the edge exposing unit EEW2, and loads the cooled wafer W into the edge exposing unit EEW2. While spinning the wafer W loaded therein, the edge exposing unit EEW2irradiates peripheral regions of the wafer W with light from the light emitter not shown, thereby exposing the peripheral regions of the wafer W (step S110).

The main transport mechanism T2, holding the wafer W received from the edge exposing unit EEW2, accesses the receiver PASS5. The main transport mechanism T2places the wafer W on the receiver PASS5A(step S11), and holds a wafer W present on the receiver PASS5B(step S16).

The main transport mechanism T2moves to one of the cooling units CP2, and replaces a wafer W in the cooling unit CP2with the wafer W held by the main transport mechanism T2. The main transport mechanism T2holds the wafer W having received cooling treatment, and accesses one of the developing units DEV2. The cooling unit CP2starts treatment of the newly loaded wafer W (step S17).

The main transport mechanism T2takes a developed wafer W from the developing unit DEV2, and places the cooled wafer W on the spin holder77of the developing unit DEV2. The developing unit DEV2develops the wafer W placed on the spin holder77(step S18). Specifically, while the spin holder77spins the wafer W in horizontal posture, the developer is supplied from one of the slit nozzles81ato the wafer W, thereby developing the wafer W.

The main transport mechanism T2holds the developed wafer W, and accesses one of the heating units HP2. The main transport mechanism T2takes a wafer W out of the heating unit HP2, and loads the wafer W it is holding into the heating unit HP2. Then, the main transport mechanism T2transports the wafer W taken out of the heating unit HP2to one of the cooling units CP2, and takes out a wafer W already treated in this cooling unit CP2. The heating unit HP2and cooling unit CP2carry out predetermined treatments for the newly loaded wafers W, respectively (steps S19and S20).

Subsequently, the main transport mechanism T2accesses the receiver PASS2again, and repeats the above operation. This operation is controlled by the third controller95. As a result, the wafers W are forwarded to the receiver PASS5Bin the order in which they are placed on the receiver PASS2A. Similarly, the wafers W are forwarded to the receiver PASS2Bin the order in which they are placed on the receiver PASS5B.

Next, operations taking place when the main transport mechanism T1could not place a wafer W on the receiver PASS2in the above step S9, and placed the wafer W on the buffer BF2instead, will be described. In this case, the third controller95controls the main transport mechanism T2to place the wafer W it is holding on the receiver PASS2B(Step S21). Then, omitting the substrate transport corresponding to step S9of the main transport mechanism T2, the third controller95lowers the main transport mechanism T2to the position opposed to the buffer BF2, and causes the main transport mechanism T2to hold the wafer W placed on the buffer BF2. When the wafer W has been received from the buffer BF2, the main transport mechanism T2resumes substrate transport in the above steps S10et seq. That is, the main transport mechanism T2transports the received wafer W to the edge exposing unit EEW2(step S10).

Thus, the main transport mechanism T2can directly receive the wafer W which the main transport mechanism T1has placed on the buffer BF2. The wafer W can be transferred efficiently, compared with the case where the main transport mechanism T1places the wafer W first placed on the buffer BF2on the receiver PASS2again, and the main transport mechanism T2receives the wafer W from the receiver PASS2. Therefore, even when the main transport mechanism T1cannot place a wafer W on the receiver PASS2, the wafer W can be transferred efficiently.

Next, operations taking place when the main transport mechanism T2cannot place the wafer W on the receiver PASS2in the above step S21will be described. The third controller95controls the main transport mechanism T2to omit the substrate transport corresponding to step S21of the main transport mechanism T2and place the wafer W on the buffer BF2. Subsequently, the main transport mechanism T2is made to carry out the substrate transport in the above steps S9et seq.

It is preferable in this case that the main transport mechanism T1skips the above step S21(to receive the wafer W from the receiver PASS2B), accesses the buffer BF2, and receives the wafer W from the buffer BF2.

Thus, even when the main transport mechanism T2cannot place a wafer W on the receiver PASS2. the main transport mechanism T2, by placing the wafer W on the buffer BF2, can promptly shift to operation for transporting other wafers W. On the story K2of the developing block Bb, therefore, a series of treatments can be carried out for a plurality of wafer W on time (as scheduled). There is no possibility of lowering the quality of development carried out for the wafers W.

[IF Transport Mechanisms TIF—IF First Transport Mechanism TIFA]

IF first transport mechanism TIFAaccesses the receiver PASS5, and receives the wafer W present on the receiver PASS5A(step S11a). IF first transport mechanism TIFA, holding the wafer W received, moves to the receiver PASS-CP, and loads the wafer W on the receiver PASS-CP (step S12).

Next, IF first transport mechanism TIFAreceives a wafer W from the receiver PASS7(step S14), and moves to a position opposed to one of the heating and cooling units PHP2. IF first transport mechanism TIFAtakes a wafer W having received post-exposure baking treatment (PEB) treatment from the heating and cooling unit PHP2, and loads the wafer W received from the receiver PASS7into the heating and cooling unit PHP2. The heating and cooling unit PHP2carries out heat treatment for the newly loaded wafer W (step S15a).

IF first transport mechanism TIFAtransports the wafer W taken out of the heating and cooling unit PHP2to the receiver PASS5B. Subsequently, IF first transport mechanism TIFAtransports a wafer W from the receiver PASS6Ato the receiver PASS-CP (Step S11b, S12). Next, IF first transport mechanism TIFAtransports a wafer W from the receiver PASS7to one of the heating and cooling units PHP4. At this time, IF first transport mechanism TIFAtakes out a wafer W having received the post-exposure baking treatment (PEB) treatment in the heating and cooling unit PHP4, and places the wafer W on the receiver PASS6B(steps S14, S15b, S16b).

Subsequently, IF first transport mechanism TIFAaccesses the receiver PASS5again and repeats the above operation. This operation is controlled by the sixth controller98.

Next, operations taking place when IF first transport mechanism TIFAcannot place the wafer W in receiver PASS5Bin the above step S16will be described. The sixth controller98controls IF first transport mechanism TIFAto omits the substrate transport by IF first transport mechanism TIFAcorresponding to step S16, and place the wafer W on the return buffer BFIFB. Subsequently, the sixth controller98causes IF first transport mechanism TIFAto carry out the transport in the above steps S11band S12et seq.

Thus, even when IF first transport mechanism TIFAcannot place a wafer W on the receiver PASS5B, IF first transport mechanism TIFA, by placing the wafer W on the return buffer BFIFB, can successively unload wafers W having undergone post-exposure baking (PEB) treatment from the heating and cooling units PHP2on time. Therefore, even when a wafer W cannot be placed on the receiver PASS5B, the post-exposure baking (PEB) treatment can be carried out for wafers W effectively.

[IF Transport Mechanisms TIF—IF Second Transport Mechanism TIFB]

IF second transport mechanism TIFBtakes a wafer W out of the receiver PASS-CP, and transports it to the exposing machine EXP. Then, IF second transport mechanism TIFBreceives an exposed wafer W from the exposing machine EXP, and transports it to the receiver PASS7(step S13).

Subsequently, IF second transport mechanism TIFBaccesses the receiver PASS-CP again and repeats the above operation.

In the substrate treating apparatus according to this embodiment, as described above, the receivers PASS2and PASS4have the buffers BF2and BF4corresponding thereto, respectively. Even when the main transport mechanism T1or T3cannot place a wafer W on the receiver PASS2or PASS4, the main transport mechanism T1or T3can place that wafer W on the buffer BF2or BF4. Thus, the main transport mechanism T1or T3can continue transporting wafers W. Even if other wafers W are being treated in the film forming section (coating units31and heat-treating units41) when the main transport mechanism T1or T3becomes incapable of placing a wafer W on the receiver PASS2or PASS4, a series of treatments including coating treatment and heat treatment can be continued for those other wafers W on time. Thus, there is no possibility of lowering the quality of treatment to form film (resist film and anti-reflection film) on the wafers W.

Since the buffers BF2and BF4are arranged adjacent the receivers PASS2and PASS4, respectively, an amount of movement required for the main transport mechanism T1or T3to access the buffer BF2or BF4does not differ greatly from an amount of movement required to access the receiver PASS2or PASS4. Therefore, a time taken when accessing the buffer BF2or BF4can be made substantially the same as the time taken to access the receiver PASS2or PASS4. This allows the main transport mechanism T1or T3to carry out a subsequent transporting operation according to normal schedule.

The buffers BF2and BF4are open also in the direction accessed by the main transport mechanisms T2and T4, respectively. Thus, the main transport mechanism T2or T4can receive a wafer W temporarily placed on the buffer BF2or BF4. Even when the main transport mechanism T1or T3places a wafer W on the buffer BF2or BF4, the wafer W can be transferred efficiently from the main transport mechanism T1or T3to the main transport mechanism T2or T4.

Even when the main transport mechanism T2or T4of the treating block Bb cannot place a wafer W on the receiver PASS2or PASS4, the main transport mechanism T1or T3also can place that wafer W on the buffer BF2or BF4. Thus, wafers W can receive high-quality developing treatment in the treating block Bb.

Each buffer BF2or BF4can accommodate a larger number of wafers W than the number of coating units31. Thus, even if wafers W are being treated in all the coating units31when it becomes impossible for the main transport mechanism T2or T4to place a wafer W on the receiver PASS2or PASS4, all these wafers W under treatment can receive the series of treatment following the coating treatment according to a predetermined schedule. This prevents lowering in the quality of treatment for forming film on these wafers W.

Since each of the receivers PASS1-PASS6has a sensor Sp for detecting presence or absence of a wafer W, the control section90(specifically, the controllers93-99) can determine properly whether a wafer W can be placed on each of the receivers PASS1-PASS6.

The treating section3is divided into the two, upper and lower, stories, and wafers W can receive a series of treatments in parallel on the respective stories. Thus, the apparatus has an increased throughput. The treating section3has a layered structure with the stories arranged one over the other. The stories are arranged vertically as are the main transport mechanism T1and main transport mechanism T3, for example. This arrangement can avoid an enlarged installation area of this apparatus.

This invention is not limited to the foregoing embodiment, but may be modified as follows:

(1) In the foregoing embodiment, the buffer BF2is stacked under the receiver PASS2, but the invention is not limited to this. For example, the buffer BF2may be disposed over the receiver PASS2, or may be juxtaposed with the receiver PASS2. Even with such a modification, the main transport mechanism T1can easily access the buffer BF2. A similar modification may be made to the buffer BF4.

(2) In the foregoing embodiment, the buffer BF2is open at opposite ends facing the main transport mechanism T1and main transport mechanism T2to be accessible also to the main transport mechanism T2. The invention is not limited to this construction. For example, the buffer BF2may be open only at the end facing the main transport mechanism T1to be accessible only to the main transport mechanism T1. A similar modification may be made to the buffer BF4.

(3) In the foregoing embodiment, each of the buffers BF2and BF4has been described as capable of accommodating five wafers W. This is not limitative. Instead, for example, the buffer BF2may be modified to accommodate at least the number of wafers W that can be treated simultaneously in the film forming section on the story K1. Similarly, the buffer BF4may be modified to accommodate at least the number of wafers W that can be treated simultaneously in the film forming section on the story K3. This construction allows all the wafers W that can be treated simultaneously in the film forming section to be temporarily placed on the buffers BF2and BF4. Therefore, whenever timing causes wafers W to be incapable of being placed on the receiver PASS2or receiver PASS4, these wafers W can be placed on the buffer BF2or BF4after continuing a series of treatments including coating treatment and heat treatment on time for all the wafers W treated in the film forming section.

Alternatively, the buffer BF2may be modified to accommodate the number of wafers W at least corresponding to the sum of the number of coating units31on the story K1and the number of developing units DEV on the story K2. Similarly, the buffer BF2may be modified by taking into account the number of developing units DEV on the story K4. With this construction, even when it becomes impossible for the main transport mechanism T2or T4of the treating block Bb to place wafers W on the receiver PASS2or receiver PASS4, the wafers W treated in the developing units DEV then can be developed with high quality.

(4) In the foregoing embodiment, the control section90determines presence or absence of a wafer W on each of the receivers PASS1-PASS6based on a result of detection by a sensor Sp. The invention is not limited to this. Instead, for example, it may be determined from controls of the main transport mechanisms T1and T2carried out by the second and third controllers94and95, whether the main transport mechanism T2has received a wafer W from the receiver PASS2after the main transport mechanism T1placed the wafer W on the receiver PASS2. If the wafer W has been received, it may be determined that the receiver PASS2has no wafer W (i.e. is vacant).

(5) Although each of the buffers BF2, BF4and BFIF similarly has a sensor for detecting presence or absence of a wafer W, the sensor may be omitted as appropriate as long as whether each buffer BF is loaded with a wafer W can be determined.

(6) In the foregoing embodiment, the treating block Ba includes the anti-reflection film coating units BARC. The invention is not limited to this. A treating block including anti-reflection film coating units may be provided separately from the treating block Ba. Or the anti-reflection film coating units BARC may be omitted.

(7) In the foregoing embodiment, the treating section3has a layered structure with two, upper and lower, stories. The invention is not limited to this. The treating section3may be divided into three or more stories. Or it is not necessary for the treating section3to have a layered structure (i.e. the treating section3may consist of one story).

The modifications in paragraphs (6) and (7) above will be described with reference toFIG. 13.FIG. 13a plan view showing an outline of a modified substrate treating apparatus. Like reference numerals are used to identify like parts which are the same as in the foregoing embodiment and will not be described again.

As shown, the treating section3may be modified to include three treating blocks B arranged horizontally. Specifically, an anti-reflection film coating block Bc, a resist film coating block Bd and a developing block Be are arranged in order from the ID section1, with the developing block Be disposed adjacent the IF section5.

The anti-reflection film coating block Bc has an anti-reflection film coating unit BARC, heat-treating units41, and a main transport mechanism T9for transporting wafers W to and from the anti-reflection film coating unit BARC and heat-treating units41.

The resist film coating block Bd has a resist film coating unit RESIST, heat-treating units41and a main transport mechanism T1for transporting wafers W to and from the resist film coating unit RESIST and heat-treating units41.

The developing block Be has a developing unit DEV, heat-treating units42, an edge exposing unit EEW and a main transport mechanism T2.

A receiver PASS9is provided between the anti-reflection film coating block Bc and resist film coating block Bd. The receiver PASS9is used to transfer wafers W between the main transport mechanism T3and main transport mechanism T1. A buffer BF9is provided adjacent the receiver PASS9. When the main transport mechanism T3cannot place a wafer W on the receiver PASS9, the wafer W is temporarily placed on the buffer BF9. The main transport mechanism T3corresponds to the third main transport mechanism in this invention. The receiver PASS9corresponds to the third receiver in this invention. The buffer BF9corresponds to the third buffer in this invention.

Each of the above treating blocks Bc-Be is not divided into a plurality of stories. Therefore, the treating section3does not have a layer structure with a plurality of stories (it has a single-story structure).

In such modified embodiment, since the receiver PASS9has the buffer BF9corresponding thereto, even when the main transport mechanism T3cannot place a wafer W on the receiver PASS9, the main transport mechanism T9can place the wafer W on the buffer BF9. Thus, the main transport mechanism T9can continue transporting wafers W. The anti-reflection film coating block Bc can effectively carry out treatment for forming anti-reflection film on the wafers W.

(8) In the foregoing embodiment, the films formed on the wafers W in the treating block Ba are resist film and anti-reflection film. The invention is not limited to this. A modification may be made to form other types of film on the wafers W.

(9) In the foregoing embodiment, each of the receivers PASS1-PASS6has a plurality of (two) receivers, and one of the receivers PASS is selected according to a direction for transferring wafers W. The invention is not limited to this. Each of the receivers PASS1-PASS6may consist of a single receiver. In this case, wafers W transferred in whichever direction may be placed on the single receiver PASS.