Determining apparatus for determining object stored in cassette

Apparatus determines whether a stored object is a wafer alone or a frame unit formed by uniting the wafer and a ring frame. The apparatus includes first and second detecting units, the second detecting unit being stored more shallowly than the first detecting unit. The apparatus determines whether light transmitted by the first detecting unit is blocked by the object and does not reach a light receiving portion of the first detecting unit. When light transmitted from the second detecting unit is blocked by the object and does not reach a light receiving portion of the second detecting unit, the apparatus determines that the object is the frame unit, whereas when the light transmitted from the second detecting unit is not blocked by the object and reaches the light receiving portion of the second detecting unit, the apparatus determines that the object is the wafer.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a determining apparatus for determining an object such as a wafer stored in a cassette (storing means).

Description of the Related Art

A plurality of devices such as integrated circuits (ICs) and large-scale integrations (LSIs) are formed on the front side of a wafer. The back side of the wafer having the plural devices on the front side is ground to reduce the thickness of the wafer to a predetermined thickness. Thereafter, the wafer is divided into individual device chips by using a processing apparatus. The device chips thus obtained are mounted in electronic equipment such as mobile phones and personal computers.

In general, the wafer is stored in a cassette (storing means) to transfer the wafer to a processing apparatus such as a grinding apparatus and a cutting apparatus. Particularly in a process (so-called front-end process) of forming semiconductor devices on the front side of the wafer, a cassette called front opening unified pod (FOUP) is used to prevent a problem such that dust or the like present in the atmosphere may adhere to the front side of the wafer. Such an FOUP cassette has a closing mechanism (door or lid) for closing a front opening. Accordingly, a storing space defined in the cassette can be enclosed by the closing mechanism in transferring the wafer. The processing apparatus is provided with a mount table (which will be hereinafter referred to as load port) for mounting the cassette as storing means thereon. When the FOUP cassette is placed on the load port and the closing mechanism of the FOUP cassette is opened (the door or lid is opened), transfer means included in the processing apparatus is allowed to gain access to the wafer stored in the FOUP cassette.

In some case, a wafer alone is stored in storing means such as a cassette. In another case, a frame unit formed by uniting a wafer and a ring frame (annular frame) is also stored in such storing means, wherein a tape is supported at its peripheral portion to the ring frame, and the wafer is attached to the central portion of the tape. Further, there is a cassette capable of storing both a wafer alone and such a frame unit. However, a conventional load port is designed so as to be dedicated to storing means for storing a wafer alone or storing means for storing a frame unit. That is, a conventional processing apparatus must include two kinds of load ports responding to the storing means for the wafer alone and the storing means for the frame unit.

Japanese Patent Laid-open No. 2014-241333 discloses a load port realizing the functions of such two kinds of load ports. That is, this load port can determine whether the cassette placed thereon is a cassette storing a wafer alone or a cassette storing a frame unit.

SUMMARY OF THE INVENTION

However, in the case of using a cassette capable of storing both a wafer alone and a frame unit, the kind of the cassette can be determined, but the kind of the object stored in the cassette cannot be determined. The processing apparatus is operated to select transfer means fit for the kind of the object and then load this object into the processing apparatus by using this transfer means. However, unless the kind of the object can be determined, the transfer means fit for the kind of the object cannot be used. Particularly in the case of the FOUP cassette as mentioned above, the inside of the cassette cannot be visually recognized in the closed condition of the closing mechanism. Accordingly, an operator cannot visually determine the kind of the object stored in the FOUP cassette and therefore cannot input the kind of the object into the processing apparatus.

It is therefore an object of the present invention to provide a determining apparatus which can reliably determine whether the object stored in the cassette is a wafer alone or a frame unit formed by uniting the wafer and a ring frame.

In accordance with an aspect of the present invention, there is provided a determining apparatus for determining whether an object stored by storing means having a storing space is a wafer alone or a frame unit formed by uniting the wafer and a ring frame; the determining apparatus including first detecting means adapted to be inserted in the storing space and second detecting means adapted to be inserted in the storing space more shallowly than the first detecting means; each the first detecting means and the second detecting means including a light transmitting portion and a light receiving portion spaced from each other by a predetermined distance in a horizontal direction; the determining apparatus further including determining means for determining whether the object is the wafer or the frame unit in the condition where the first detecting means and the second detecting means are inserted in the storing space to a predetermined position where light transmitted from the light transmitting portion of the first detecting means is blocked by the object and does not reach the light receiving portion of the first detecting means; wherein when light transmitted from the light transmitting portion of the second detecting means is blocked by the object and does not reach the light receiving portion of the second detecting means, the determining means determines that the object is the frame unit, whereas when the light transmitted from the light transmitting portion of the second detecting means is not blocked by the object and reaches the light receiving portion of the second detecting means, the determining means determines that the object is the wafer.

Preferably, the object includes a plurality of objects stored in the storing space of the storing means, and the determining means determines whether each of the objects is the wafer or the frame unit by scanning the first detecting means and the second detecting means in a vertical direction in the condition where the first detecting means and the second detecting means are inserted in the storing space to the predetermined position.

Preferably, the determining apparatus further includes third detecting means for detecting the frame unit; the third detecting means having a light transmitting portion and a light receiving portion spaced from each other by a predetermined distance in a horizontal direction parallel to a line connecting the light transmitting portion and the light receiving portion of the first detecting means, the predetermined distance between the light transmitting portion and the light receiving portion of the third detecting means being shorter than the predetermined distance between the light transmitting portion and the light receiving portion of the first detecting means; the determining means determining whether or not the object is the frame unit in the condition where the light transmitted from the light transmitting portion of the first detecting means is blocked by the object and does not reach the light receiving portion of the first detecting means; wherein when light transmitted from the light transmitting portion of the third detecting means is reflected on the object and then reaches the light receiving portion of the third detecting means, the determining means determines that the object is the frame unit.

The determining apparatus of the present invention is provided in the vicinity of a load port of a processing apparatus. Prior to loading the object (the wafer or the frame unit) into the processing apparatus, the kind of the object stored in the storing means can be determined by the determining apparatus. Particularly in the case that the storing means is an FOUP cassette having a door, the determining apparatus can determine the kind of the object in the condition where the door of the FOUP cassette is open in loading the object into the processing apparatus. After determining the kind of the object stored in the cassette, it can be decided which of transfer means fit for the wafer alone and transfer means fit for the frame unit is to be used in loading the object into the processing apparatus. Accordingly, suitable transfer means in the processing apparatus can be operated to gain access to the object stored in the cassette.

The determining apparatus of the present invention is widely applicable to any storing means having a storing space into which the first and second detecting means can be inserted. That is, the determining apparatus of the present invention is also applicable to any cassettes other than the FOUP cassette. In any cassettes other than the FOUP cassette, the object stored in each cassette can be visually recognized from the outside thereof. However, when placing the cassette on the load port of the processing apparatus, an operator is required to input and record the kind of the object into the processing apparatus. In the case that the determining apparatus of the present invention is provided between the cassette and a load/unload opening of the processing apparatus, the kind of the object stored in the storing space of the cassette can be automatically determined by the determining apparatus. Accordingly, it is unnecessary for the operator to input the kind of the object into the processing apparatus, but the suitable transfer means in the processing apparatus can be operated to gain access to the object stored in the cassette. Thus, the determining apparatus of the present invention is useful not only for an FOUP cassette, but also for any other cassettes.

According to the present invention, it is possible to provide a determining apparatus which can reliably determine whether the object stored in the cassette is a wafer alone or a frame unit formed by uniting the wafer and a ring frame.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A preferred embodiment of the present invention will now be described. An object to be stored in storing means will first be described. The object is a target to be determined by a determining apparatus according to this preferred embodiment.FIG. 1Adepicts a wafer1alone as an example of the object to be stored in the storing means. The wafer1is formed of silicon or SiC (silicon carbide), for example. The wafer1may be formed of any other semiconductor materials or other materials such as sapphire, glass, and quartz. The wafer1as a target to be determined by the determining apparatus according to this preferred embodiment is a substantially disk-shaped wafer. However, the determining apparatus of the present invention may be configured so as to also determine a rectangular substrate.

As depicted inFIG. 1A, the front side1aof the wafer1is partitioned by a plurality of crossing division lines3to define a plurality of separate regions where a plurality of devices5such as ICs, microelectromechanical systems (MEMSs), and light-emitting diodes (LEDs) are formed. The wafer1is finally divided along the division lines3to obtain a plurality of device chips.FIG. 1Bdepicts a frame unit11formed by uniting the wafer1with a ring frame (annular frame)9as another example of the object to be stored in the storing means. As depicted inFIG. 1B, the ring frame9has a substantially circular opening, and a tape7is attached at its peripheral portion to the ring frame9so as to close the opening of the ring frame9. Further, the wafer1is attached to the central portion of the tape7exposed to the opening of the ring frame9. Thus, the wafer1is supported through the tape7to the ring frame9to thereby form the frame unit11as a unit of the wafer1, the tape7, and the ring frame9. As described above, the devices5are formed in the respective separate regions defined by the division lines3on the front side1aof the wafer1. The ring frame9has a flat side surface9a. As will be described later, a determining apparatus22functions to apply light to the flat side surface9aof the ring frame9and detect the light reflected from the flat side surface9a, thereby determining that the object stored in the storing means is the frame unit11. In contrast, the wafer1has a curved side surface. Accordingly, when light is applied to the curved side surface of the wafer1, the light is not reflected toward the determining apparatus22, that is, the light is not detected by the determining apparatus22. In this case, the determining apparatus22determines that the object stored in the storing means is the wafer1alone. The configuration of the determining apparatus22will be hereinafter described in detail.

The storing means for storing the object including the wafer1will now be described.FIG. 2Ais a schematic perspective view of storing means2afor storing the wafer1alone as an example of the storing means (cassette). As depicted inFIG. 2A, the storing means2acan store a plurality of wafers1in a stacked manner. The storing means2ahas a front side where an inlet/outlet portion4ais formed as an opening to allow the pass of the wafer1. A storing space6ais defined in the storing means2a, wherein the wafer1is adapted to be inserted from the inlet/outlet portion4ainto the storing space6a. The storing space6ais defined by a pair of side wall members12aand an upper wall member14aconnecting the side wall members12aat their upper ends. The inside surface of each side wall member12ais formed with a rack8ahaving a plurality stages. The wafer1inserted into the storing space6ais adapted to be placed on any one of the plural stages of each rack8a(on the opposite stages of the pair of racks8aat the same height). In storing the wafer1into the storing space6a, the wafer1is vertically moved to a desired height corresponding to any one of the plural stages of each rack8aand next inserted into the storing space6ato a predetermined horizontal position on the predetermined stage. The upper surface of the upper wall member14ais provided with a handle16afor use in transferring the storing means2a.

The configuration of the storing means (cassette)2amay be suitably modified, provided that the storing means2ahas a fundamental configuration. For example, the upper wall member14aor the side wall members12amay not be provided. Further, the storing means2amay further include a lower wall member or a rear wall member. The handle16amay be provided on any portion of the storing means2aother than the upper wall member14a. Further, the handle16amay be replaced by a connecting mechanism (not depicted) to be mounted to transfer means installed in a clean room or the like, wherein the storing means2ais transferred by the transfer means through the connecting mechanism.

FIG. 2Bis a schematic perspective view of storing means2bfor storing the frame unit11as another example of the storing means. The storing means2bdepicted inFIG. 2Bhas a fundamental configuration similar to that of the storing means2adepicted inFIG. 2A. Specifically, the storing means2bhas an inlet/outlet portion4bas an opening and a storing space6b, wherein the frame unit11is adapted to be inserted from the inlet/outlet portion4binto the storing space6b. The storing space6bis defined by a pair of side wall members12band a structure14bconnecting the side wall members12bat their upper ends. The inside surface of each side wall member12bis formed with a rack8bhaving a plurality of stages. The frame unit11inserted into the storing space6bis adapted to be placed on any one of the plural stages of each rack8b. The structure14bconnecting the side wall members12bmay be provided on the lower side of the storing means2b.

FIG. 2Cis a schematic perspective view of FOUP type storing means2cas still another example of the storing means. As depicted inFIG. 2C, the FOUP type storing means2chas an inlet/outlet portion4cas an opening on the front side, a lid (door)10for closing the inlet/outlet portion4c, and a housing for enclosing a storing space6cexcept the inlet/outlet portion4c, wherein the lid10is closed to enclose the storing space6cat all times except in the case of storing the object into the storing space6cor taking the object out of the storing space6c. By closing the lid10, the entry of dust or the like present in the atmosphere into the storing space6ccan be suppressed, so that the storing space6ccan be kept clean to thereby prevent the contamination of the object stored in the storing space6c. Thus, when the lid10is in a closed condition, the cleanness of the storing space6ccan be maintained at a high level. Accordingly, if the cleanness of an external environment outside the storing means2cis maintained at a predetermined level, it is unnecessary to increase a cost for improving the cleanness of the external environment to a higher level. The housing of the storing means2cis composed of a pair of side wall members12c, an upper wall member14c, a rear wall member (not depicted), and a lower wall member (not depicted). The inside surface of each side wall member12cis formed with a rack8chaving a plurality of stages. A handle16cis mounted on the outer surface of each side wall member12c. The storing means2cmay be configured so that it can store both the wafer1alone and the frame unit11.

When the FOUP type storing means2cis placed on a load port of a processing apparatus and the lid10is next opened, the object stored in the storing means2cis allowed to be loaded into the processing apparatus. The wafer1alone or the frame unit11inserted into the storing space6cis placed on any one of the plural stages of each rack8c. After loading the object into the processing apparatus, the lid10is closed again. In the closed condition of the lid10of the storing means2c, the kind of the object stored in the storing space6ccannot be visually determined unless the housing of the storing means2cis transparent. Further, the lid10of the storing means2cis opened only when the storing means2cis placed on the load port and the inlet/outlet portion4cis opposed to a load/unload opening of the processing apparatus as will be described later. Accordingly, even in this condition, it is not easy to visually determine the kind of the object stored in the storing space6c. To cope with this problem, the determining apparatus according to this preferred embodiment is configured so as to determine the kind of the object stored in the storing space6c. According to the result of this determination, the processing apparatus selects the proper transfer means to allow the access to the object stored in the storing space6c.

The determining apparatus according to this preferred embodiment will now be described.FIG. 3is a schematic perspective view depicting a load port20of a processing apparatus (not depicted), storing means2placed on the upper surface of the load port20, and a determining apparatus22for determining the kind of the object stored in the storing means2. The processing apparatus has a load/unload opening24for allowing the pass of the object stored in the storing means2. The load/unload opening24is normally closed by a door (not depicted). The storing means2has an inlet/outlet portion4as an opening adapted to be opposed to the load/unload opening24of the processing apparatus. That is, the storing means2is placed on the load port20in the condition where the inlet/outlet portion4is opposed to the door closing the load/unload opening24of the processing apparatus. In this condition, the storing means2is moved toward the load/unload opening24of the processing apparatus by a predetermined distance, and the door closing the load/unload opening24is next opened. In this condition, transfer means included in the processing apparatus or the determining apparatus22can gain access through the inlet/outlet portion4to the object stored in the storing space6defined by the storing means2. The determining apparatus22is located in the vicinity of the load/unload opening24of the processing apparatus. The determining apparatus22is vertically movable between an upper position as an access position and a lower position as a retract position. That is, when the determining apparatus22is operated to perform the determination of the object, the determining apparatus22is raised to the access position where detecting means to be hereinafter described can be inserted into the storing space6of the storing means2. Conversely, when the transfer means of the processing apparatus is operated to load/unload the object through the load/unload opening24, the determining apparatus22is lowered to the retract position so as not to interfere with the transfer means.

FIG. 3depicts an FOUP type cassette as an example of the storing means2. However, the storing means2adapted to be placed on the load port20of the processing apparatus is not limited to such an FOUP type cassette. In the case that the storing means2is not an FOUP type, the kind of the object stored in the storing means2can be visually determined. However, in general, an operator is required to input the kind of the object into the processing apparatus in order that proper transfer means in the processing apparatus can gain access to the object. To the contrary, the determining apparatus22according to this preferred embodiment can eliminate the need for inputting the kind of the object from the operator. That is, the kind of the object can be determined by the determining apparatus22, and the kind thus determined can be automatically input into the processing apparatus. There will now be described the components of the determining apparatus22and the determination by the determining apparatus22.

FIG. 4Ais a schematic plan view depicting a first case that the frame unit11is stored in the storing space6of the storing means2and this frame unit11is determined by the determining apparatus22, andFIG. 4Bis a schematic plan view depicting a second case that the wafer1is stored in the storing space6and it is determined by the determining apparatus22. InFIGS. 4A and 4B, first detecting means and second detecting means are included in the determining apparatus22and they are inserted in the storing space6of the storing means2. The first detecting means and the second detecting means will be hereinafter described in detail. The components of the determining apparatus22will now be described with reference toFIG. 4A. As depicted inFIG. 4A, the determining apparatus22includes a platelike base (supporting means)26located in the vicinity of the load/unload opening24(seeFIG. 3) of the processing apparatus. The base26is supported through an elevating mechanism (not depicted) to the processing apparatus. That is, the base26is vertically movable between an upper detection position and a lower retraction position. The base26has a first surface opposed to the load/unload opening24in the condition where the base26is set at the upper detection position. The base26has a length in a first direction D1(width direction) parallel to the first surface, i.e., in a horizontal direction. This length (width) of the base26in the first direction D1is larger than the length of the inlet/outlet portion (seeFIG. 3) of the storing means2in the first direction D1. Further, the base26has a length in a second direction D2(thickness direction) perpendicular to the first surface. This length (thickness) of the base26in the second direction D2is set so as to accommodate a determining unit (determining means) (not depicted) constituting the determining apparatus22. However, the size of the base26is not especially limited.

A pair of first and second projections30aand30bare provided at the upper end of the base26so as to project toward the load/unload opening24. The first and second projections30aand30bare spaced from each other in the first direction D1and located at substantially the same height. Each the first and second projections30aand30bis a rodlike member formed of stainless steel, for example. The first and second projections30aand30bhave the same length. However, the manner of mounting the first and second projections30aand30bis not especially limited. For example, the first and second projections30aand30bmay be indirectly mounted to the base26. More specifically, the first and second projections30aand30bmay be supported to a rodlike support member (detecting means support member28) extending in the first direction D1, and this detecting means support member28may be fixed to the base26. In this preferred embodiment, the first and second projections30aand30bare supported to the detecting means support member28as depicted inFIGS. 4A and 4B.

The detecting means support member28is movable toward the storing means2placed on the load port20by operating a horizontal moving mechanism (not depicted) including a motor or the like. Accordingly, the first and second projections30aand30bsupported to the detecting means support member28can be inserted into the storing space6of the storing means2. As a modification, the detecting means support member28may have a horizontal moving mechanism for moving the first and second projections30aand30btoward the storing means2. That is, the horizontal movement of the first and second projections30aand30bmay be made independent of the horizontal movement of the detecting means support member28. All of the base (supporting means)26, the detecting means support member28, and the first and second projections30aand30bconstituting the determining apparatus22are formed of stainless steel, for example. Each of these components has a hollow structure for allowing the routing of electrical wires or optical fibers, wherein the electrical wires are used as communication lines for detecting means and control means to be hereinafter described, and the optical fibers are used to guide light for the detecting means. However, the material and shape of these structures are not especially limited.

A light transmitting portion32aincluded in the first detecting means is provided in the vicinity of the front end of the first projection30a, and a light transmitting portion34aincluded in the second detecting means is provided on the first projection30aso as to be spaced from the light transmitting portion toward the base end of the first projection30a. Further, a light receiving portion32bincluded in the first detecting means is provided in the vicinity of the front end of the second projection30b, and a light receiving portion34bincluded in the second detecting means is provided on the second projection30bso as to be spaced from the light receiving portion32btoward the base end of the second projection30b. In the first detecting means, the light transmitting portion32aand the light receiving portion32bmay be exchanged in position. Similarly, in the second detecting means, the light transmitting portion34aand the light receiving portion34bmay be exchanged in position. The light transmitting portion32aof the first detecting means is spaced by a predetermined distance from the light receiving portion32bof the first detecting means in the axial direction of the detecting means support member28. This predetermined distance is set so that a part of the object stored in the storing means2can be interposed between the light transmitting portion32aand the light receiving portion32band that both the light transmitting portion32aand the light receiving portion32bcan be simultaneously inserted in the storing space6. Similarly, the light transmitting portion34aof the second detecting means and the light receiving portion34bof the second detecting means are spaced by this predetermined distance from each other in the axial direction of the detecting means support member28. As a modification, the first and second projections30aand30bsupported to the detecting means support member28may be movable on the detecting means support member28in the axial direction thereof. In this case, the spacing between the first and second projections30aand30bcan be adjusted to the above predetermined distance according to the size of the storing means2and the size of the object. That is, the horizontal positions of the first and second projections30aand30bin the axial direction of the detecting means support member28can be changed according to the size of the storing space6and the size of the object.

The first and second projections30aand30bare inserted into the storing space6to a predetermined position where a part of the object stored in the storing space6is interposed between the first and second projections30aand30b. As described above, the light transmitting portion32aand the light receiving portion32bof the first detecting means are set in a horizontal position deeper than that of the light transmitting portion34aand the light receiving portion34bof the second detecting means in the storing space6. That is, the second detecting means is inserted into the storing space6to a horizontal position shallower than that of the first detecting means. The light transmitting portion32aof the first detecting means functions to transmit light to the light receiving portion32bof the first detecting means. If anybody blocking the light is absent, for example, if the object stored in the storing means2is absent between the light transmitting portion32aand the light receiving portion32b, the light transmitted from the light transmitting portion32ais allowed to reach the light receiving portion32b, so that the light is received by the light receiving portion32b. The light transmitting portion34aand the light receiving portion34bof the second detecting means also function similarly.

Each the first and second detecting means uses a light source such as LED and laser beam oscillator. However, it is unnecessary to provide the light source in the first projection30a. That is, the light source may be provided on the base (supporting means)26or outside the determining apparatus22. In this case, an optical fiber or the like may be provided in the detecting means support member28and the first projection30a, thereby guiding the light emitted from the light source through the optical fiber to the light transmitting portions32aand34aof the first and second detecting means. Thus, the light is transmitted from the light transmitting portions32aand34ato the light receiving portions32band34bof the first and second detecting means, respectively. Further, each the first and second detecting means uses a photodetector such as charge-coupled device (CCD) and complementary metal oxide semiconductor (CMOS). However, it is unnecessary to provide the photodetector in the second projection30b. That is, the photodetector may be provided on the base (supporting means)26or outside the determining apparatus22. In this case, an optical fiber or the like may be provided in the second projection30bor the detecting means support member28, thereby guiding the light received by the light receiving portions32band34bof the first and second detecting means, from the light receiving portions32band34bthrough the optical fiber to the photodetector. Thus, the light received by the light receiving portions32band34bis detected by the photodetector.

The determining apparatus22further includes third detecting means composed of a light transmitting portion36aand a light receiving portion36bas depicted inFIGS. 4A and 4B. The light transmitting portion36aand the light receiving portion36bof the third detecting means are supported to the detecting means support member28. The light transmitting portion36aand the light receiving portion36bare spaced from each other in the first direction D1parallel to the line connecting the light transmitting portion32aand the light receiving portion32bof the first detecting means, wherein the distance between the light transmitting portion36aand the light receiving portion36bis shorter than the distance between the light transmitting portion32aand the light receiving portion32b. The light transmitting portion36aof the third detecting means functions to transmit light toward the object stored in the storing means2. The light transmitted from the light transmitting portion36aof the third detecting means is reflected by the object stored in the storing means2. In the case that the light reflected from the object reaches the light receiving portion36bof the third detecting means, the light is detected by the light receiving portion36b. Conversely, in the case that the light reflected from the object does not reach the light receiving portion36bof the third detecting means, the light is not detected by the light receiving portion36b. The light transmitting portion36aof the third detecting means may be similar in configuration to the light transmitting portions32aand34aof the first and second detecting means. Further, the light receiving portion36bof the third detecting means may be similar in configuration to the light receiving portions32band34bof the first and second detecting means.

The determining apparatus22further includes determining means (not depicted). The determining means is connected through wiring to each detecting means. The determining means functions to control the transmission of light from each light transmitting portion and also to input information on the detection of light by each light receiving portion. The determining means further functions to determine the kind of the object stored in the storing space6, according to the result of detection by each detecting means.

A determining method for the object by the determining apparatus22will now be described. First, the first and second projections30aand30bare inserted into the storing space6to a predetermined position. Thereafter, the height of the detecting means support member28is adjusted so that a part of the object stored in the storing space6is interposed between the light transmitting portion32aof the first detecting means and the light receiving portion32bof the first detecting means. The vertical movement of the detecting means support member28is effected by operating the elevating mechanism (not depicted) of the determining apparatus22to vertically move the base26as a whole. The height adjustment for the detecting means support member28is performed as transmitting light from the light transmitting portion32atoward the light receiving portion32b. When the detecting means support member28is vertically moved to the position where a part of the object is interposed between the light transmitting portion32aand the light receiving portion32b, the light transmitted from the light transmitting portion32ais blocked by the object, so that the light is not received by the light receiving portion32b. Accordingly, when the light transmitted from the light transmitting portion32ais not received by the light receiving portion32b, the determining means determines that the height of the detecting means support member28has been adjusted to a predetermined height. After finishing the height adjustment for the detecting means support member28, light is transmitted from the light transmitting portion34aof the second detecting means toward the light receiving portion34bof the second detecting means.

In the case that the object stored in the storing space6is the frame unit11as depicted inFIG. 4A, the light transmitted from the light transmitting portion34aof the second detecting means is blocked by the frame unit11, so that the light is not received by the light receiving portion34bof the second detecting means. In this case, the light is not detected by the second detecting means, and the determining means of the determining apparatus22determines that the object stored in the storing space6is the frame unit11. In contrast, in the case that the object stored in the storing space6is the wafer1alone as depicted inFIG. 4B, the light transmitted from the light transmitting portion34aof the second detecting means is not blocked by the wafer1, so that the light is received by the light receiving portion34bof the second detecting means. In this case, the light is detected by the second detecting means, and the determining means of the determining apparatus22determines that the object stored in the storing space6is the wafer1alone. Thus, by utilizing the difference in shape between the wafer1and the frame unit11, the determining means of the determining apparatus22can determine the kind of the object according to whether or not the light transmitted from the light transmitting portion34aof the second detecting means is received by the light receiving portion34bof the second detecting means. The layout of the second detecting means may be suitably changed in the range where the difference in shape between the wafer1and the frame unit11can be recognized by the second detecting means.

The above determination may be performed by using the third detecting means including the light transmitting portion36aand the light receiving portion36bin place of the second detecting means. A determining method for the object by the use of the third detecting means will now be described with reference toFIG. 5. First, the height of the detecting means support member28is adjusted so that a part of the object is interposed between the light transmitting portion32aof the first detecting means and the light receiving portion32bof the first detecting means. The height adjustment for the detecting means support member28is performed similarly to the above by using the first detecting means. After finishing the height adjustment for the detecting means support member28, light is transmitted from the light transmitting portion36aof the third detecting means toward the object stored in the storing means6.

In the case that the object stored in the storing space6is the frame unit11as depicted inFIG. 5, the light transmitted from the light transmitting portion36aof the third detecting means impinges on the flat side surface9aof the ring frame9constituting the frame unit11and is then reflected on the flat side surface9a. The light reflected from the flat side surface9areaches the light receiving portion36bof the third detecting means. In this case, the light is detected by the third detecting means, and the determining means of the determining apparatus22determines that the object stored in the storing space6is the frame unit11. In contrast, in the case that the object stored in the storing space6is the wafer1alone, the light transmitted from the light transmitting portion36aof the third detecting means impinges on the curved side surface (seeFIG. 4B) of the wafer1and is then reflected from this curved side surface. However, the light reflected from the curved side surface of the wafer1does not reach the light receiving portion36bof the third detecting means in most cases. In this case, the light is not detected by the third detecting means, and the determining means of the determining apparatus22determines that the object stored in the storing space6is the wafer1alone.

In the determining apparatus22according to this preferred embodiment, the detecting means support member28may be vertically scanned in the condition where the first and second detecting means are inserted in the storing space6of the storing means2to a predetermined position. In this case, a plurality of objects stored in the storing space6can be determined at one time. A determining method in this case will now be described.

First, the first and second projections30aand30bare inserted into the storing space6to a predetermined position. Thereafter, light is transmitted from the light transmitting portion32aof the first detecting means toward the light receiving portion32bof the first detecting means. At the same time, the detecting means support member28is vertically moved. When the light transmitted from the light transmitting portion32ais not received by the light receiving portion32b, that is, when the height of the detecting means support member28becomes equal to the height of any one of the plural objects, the second detecting means is operated to determine the object at this height. This determination is repeated for all the other objects stored in the storing space6without stopping the vertical movement of the detecting means support member28. As a result, the determining means of the determining apparatus22can determine whether the plural objects are a plurality of wafers1or a plurality of frame units11.

The storing means2has a pair of opposed racks8each having a plurality of stages, wherein the wafer1or the frame unit11can be stored on each stage. However, a plurality of objects are not always stored on all the stages of each rack8. Accordingly, unless the processing apparatus grasps the stage where the object is stored, the transfer means cannot be set at a proper height in loading the object from the storing means2to the processing apparatus. To cope with this problem, the detecting means support member28is vertically scanned in this preferred embodiment to thereby identify the stage where the object is stored. Further, in storing a plurality of objects into the storing means2, all the objects are usually of the same kind and it is therefore sufficient to determine one of the plural objects. However, there is a case that different kinds of objects may be stored into the storing means2due to any circumstances. Even in such a case, the determining apparatus22according to this preferred embodiment can determine the different kinds of objects. Accordingly, if there is a problem in kinds of the objects, any abnormality can be instantaneously detected.

After determining the kind/kinds of the objects stored in the storing means2by operating the determining apparatus22as mentioned above, the processing apparatus is operated to select suitable transfer means according to the kind/kinds of the objects on the basis of the result of determination by the determining apparatus22. Thereafter, the transfer means is operated to gain access to one of the objects stored in the storing means2and then take it out of the storing means2, thereby loading the object into the processing apparatus. At this time, the determining apparatus22is lowered to the retraction position so as not to interfere with the loading operation by the transfer means.FIGS. 6A and 6Bare schematic side views depicting different vertical positions of the determining apparatus22with respect to the storing means2placed on the load port20. More specifically,FIG. 6Adepicts an upper operative position where the storing means2has been placed on the load port20and the determining apparatus22is raised so as to face the storing means2.FIG. 6Bdepicts a lower inoperative position where the determining apparatus22is lowered in transferring the object from the storing means2to the processing apparatus. As depicted inFIG. 6A, the determining apparatus22is set at a predetermined height (upper position) for the determination of the object when the storing means2is placed on the load port20. Further, as depicted inFIG. 6B, the determining apparatus22is set at a retraction position (lower position) so as not to interfere with the loading operation of the transfer means in transferring the object from the storing means2to the processing apparatus.

According to the determining apparatus as described above, it is possible to reliably determine whether the object stored in the storing means (cassette) is a wafer alone or a frame unit formed by uniting a wafer and a ring frame.

The present invention is not limited to the above preferred embodiment, but various modifications may be made. For example, while each the first, second, and third detecting means in this preferred embodiment has a light transmitting portion for transmitting light and a light receiving portion for receiving the light transmitted from the light transmitting portion, the first, second, and third detecting means may use different wavelengths of light. In this case, each detecting means can detect only the corresponding wavelength of light, so that there is no possibility that the light transmitted from the light transmitting portion of the other detecting means may be erroneously detected.

Further, in determining whether the object stored in the storing means is the wafer alone or the frame unit, the determining apparatus in the above preferred embodiment utilizes the difference in shape between the wafer and the frame unit. As a modification, the storage position on the rack in storing the wafer alone into the storing means may be made different from that in storing the frame unit into the storing means. In this case, the determining apparatus may be configured to recognize the difference in this storage position, thereby determining the kind of the object stored in the storing means. Specifically, in the case of storing the wafer alone into the storing means, the wafer is set in a position far from the inlet/outlet portion of the storing means. On the other hand, in the case of storing the frame unit into the storing means, the frame unit is set in a position relatively near the inlet/outlet portion of the storing means. More specifically, in the case of storing the wafer alone into the storing means, the wafer is set in a position where the light transmitted from the light transmitting portion of the second detecting means is not blocked by the wafer, whereas in the case of storing the frame unit into the storing means, the frame unit is set in a position where the light transmitted from the light transmitting portion of the second detecting means is blocked by the frame unit.

Accordingly, when the light transmitted from the light transmitting portion of the second detecting means is not received by the light receiving portion of the second detecting means, it is determined that the object stored in the storing means is the frame unit. Conversely, when the light transmitted from the light transmitting portion of the second detecting means is received by the light receiving portion of the second detecting means, it is determined that the object stored in the storing means is the wafer alone. To effect this determination by the determining apparatus, the rack of the storing means may be configured so that the wafer and the frame unit are set at different positions.