JP2544056Y2 - Wafer surface treatment equipment - Google Patents

Description

[Detailed description of the invention] [Industrial application field] In this invention, a plurality of thin plate-like substrates (hereinafter, referred to as "wafers") such as semiconductors, ceramics, and glasses are stored in containers (hereinafter, referred to as "cassettes"). BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer surface treatment apparatus of a type in which various surface treatments are performed on a wafer while being housed and housed in a cassette, and particularly to a technique of wafer transfer and cassette storage, transfer, and transfer. .

[Conventional technology]

For example, semiconductor devices are manufactured by subjecting a semiconductor wafer to a number of surface treatments such as metal deposition, photoresist coating, pattern baking, development, etching, cleaning, film stripping, and impurity diffusion. Then, depending on the type of processing step, there are a case where wafers are processed one by one and a case where many wafers are processed simultaneously while a large number of wafers are housed in a cassette.

When performing wafer surface treatment with a large number of wafers stored in a cassette, the wafers are transferred from a transfer-only cassette to a processing-only cassette prior to processing, and the wafers are processed after processing. In some cases, it is necessary to transfer from a dedicated cassette to a transport-only cassette. For example, a quartz cassette is used in the heat treatment apparatus as a processing cassette, and a fluororesin cassette is used in the chemical immersion processing apparatus. Wafers can be transferred between these processing-dedicated cassettes and transport-only polypropylene cassettes. Done.

Along with this, it is necessary to transport the cassettes between a transfer device for transferring wafers between cassettes and a surface treatment device, and to temporarily store the cassettes according to the progress of processing. There may be.

Regarding these technologies, conventionally, for example, the magazine "Semicond
uctor World ”, November 1985, page 82, connects the transport line between two types of processing equipment and the transport line in the equipment via a cassette stocker, exchanges cassettes, stores, identifies lots, etc. And a technique for controlling the processing timing between the respective steps is disclosed. On page 75 of the same magazine, the wafer inlet / outlet part of the diffusion system was connected to the stocker, the wafer was transferred between the transport cassette and the quartz board, and the quartz board supporting the wafer was unloaded to the diffusion furnace. An incoming flow is disclosed.

An example of the above cassette stocker is disclosed in
Japanese Patent Publication No. 220924 (title "Stocker of Semiconductor Wafer Cassette") discloses a stocker capable of three-dimensionally storing a plurality of cassettes.

In addition, as a wafer transfer device, for example,
In Japanese Patent Application Laid-Open No. 56-44566 (title "Object Alignment Apparatus"), a table in which first and second cassettes are placed and through holes are formed at predetermined positions, and a wafer accommodated in the cassettes Vertically moving means vertically moving through the through-hole while holding the wafer, aligning means for collectively holding and aligning the wafers moved above the cassette by the vertically moving means; and There is disclosed an apparatus constituted by driving means for relatively moving the table.

Further, Japanese Patent Application Laid-Open No. 59-104138 (title of "Semiconductor Wafer Transfer Apparatus") discloses that the wafers in the cassettes are collectively held at the respective mounting positions of the first and second cassettes, Moving means, respectively, holding means for holding the wafers moved above one cassette by one vertical moving means at a time, and rotating the holding means by 180 ° above the other cassette. There is disclosed an apparatus provided with a rotating means for transferring a wafer to the other vertical moving means.

[Problems to be solved by the invention]

As described above, the manufacturing process of a semiconductor device includes various surface treatment steps. Of these, when performing wafer surface treatment while a large number of wafers are housed in a cassette, depending on the treatment step, the cassette may be processed. Due to problems such as corrosion resistance and dust prevention, a dedicated cassette is used for each processing step. In each surface processing step, a device for transferring wafers between a transfer cassette and a cassette dedicated to the processing step, and a timing related to the transfer of the cassette between the processing steps are controlled, and the cassette is temporarily stored. Cassette stockers and the like are known.

However, conventionally, the wafer transfer apparatus and the cassette stocker, and the wafer processing apparatus and the surface treatment apparatus are individually arranged independently of each other even though they are connected on the flow, so that they are placed in a clean room. Etc., the installation area occupied by the equipment becomes large, and the transportation means for transporting the cassettes between the apparatuses becomes large, which increases the equipment cost, or requires considerable labor when transporting the cassettes between the apparatuses by hand. In addition, there is a problem that the dust removal is hindered.

The present invention has been made to solve the above-mentioned problem, and has been made in order to solve the above-mentioned problem, and to transfer and transfer wafers in a surface treatment apparatus that performs various surface treatments on wafers while a plurality of wafers are housed in a cassette. It is a technical object to efficiently store, transport, and transfer a cassette in a small space.

[Means for solving the problem]

This invention is a means to achieve the above-mentioned subject,
A cassette dedicated to processing for accommodating wafers to be surface-treated,
In a wafer surface treatment apparatus that uses a transfer-only cassette that accommodates wafers to be carried in and out, a surface treatment in which a plurality of treatment tanks that perform required surface treatment on wafers housed in the treatment-only cassette are arranged Unit, a processing cassette transfer unit that is disposed along the direction in which the plurality of processing tanks are arranged, and transports a processing cassette along the arrangement direction, and is disposed on one end side of the arranged processing tanks. A wafer transfer unit for transferring a wafer between the transfer cassette and the processing cassette; and at least one of the transfer cassette and the processing cassette disposed above or beside the wafer transfer unit. A cassette storage shelf capable of storing one of them, and a transfer-only cassette, which is disposed adjacent to the wafer transfer section and on which a transfer-only cassette to be loaded and unloaded is placed. And a wafer transfer unit, at least one of the transfer cassette and the processing cassette between the wafer transfer unit and the cassette storage shelf, and the wafer transfer unit and the processing cassette transfer unit. And a cassette transfer unit for transferring a processing-only cassette between the processing-only cassette transport unit and the surface processing unit, and between the surface-processing unit and the wafer transfer unit. It is configured as a gist.

[Action]

In the wafer surface treatment apparatus configured as described above, when a transfer-only cassette is loaded into the transfer-only cassette loading / unloading table from the preceding processing apparatus, the wafer accommodated in the transfer-only cassette is transferred to the wafer. The transfer unit transfers the cassette from the transport cassette to the processing cassette.

At this time, the cassette is transferred from the wafer transfer unit to the cassette storage shelf by the cassette transfer unit and temporarily stored, or is taken out of the cassette storage shelf and transferred to the wafer transfer unit according to the progress of processing or the like. Transfer of wafers, surface treatment and transport of cassettes,
The timing between each transfer is controlled. The wafer transferred to the processing cassette is transferred from the wafer transfer unit to the cassette transfer unit by the cassette transfer unit, and transferred to the vicinity of the processing start position of the surface processing unit by the cassette transfer unit. The wafer is transferred to the surface processing unit by the wafer transfer unit, or is directly transferred from the wafer transfer unit to the surface processing unit by the cassette transfer unit. The wafer which has been subjected to the required surface treatment while being housed in the processing-dedicated cassette in the surface treatment unit is transferred from the surface treatment unit to the wafer transfer unit by the transfer unit, or the surface treatment is performed by the cassette transfer unit. From the vicinity of the processing end position of the surface treatment unit to the vicinity of the wafer transfer unit.
The wafer is transferred to the wafer transfer unit by the cassette transfer means. The plurality of wafers that have been subjected to the surface treatment in this manner are transferred from the processing-only cassette to the transfer-only cassette in the wafer transfer unit, and then unloaded from the transfer-only cassette loading / unloading unit and sent to the post-processing apparatus. It is carried out.

The cassette storage shelf is disposed above or to the side of the wafer transfer section, the surface processing section is connected at one end to the wafer transfer section, and the cassette transfer section is located at one side of the surface processing section. Since the cassettes are arranged along the sides, the operation of transferring the cassettes between the units can be performed efficiently over a short distance.

〔Example〕

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view showing an embodiment of the present invention and showing an entire surface treatment apparatus for a wafer.

This wafer surface treatment apparatus includes a wafer transfer unit 1,
A cassette storage shelf 2 provided thereabove, a surface treatment section 3 connected to the wafer transfer section 1 at one end, and a wafer transfer section along one side of the surface treatment section 3 with the other end of the surface treatment section 3. A cassette transport unit 4 for communicating with the replacement unit 1;
And a wafer transfer unit 1 and a cassette storage shelf 2, a wafer transfer unit 1 and a cassette transfer unit 4, a cassette transfer unit 4 and a surface treatment unit 3, and a surface treatment unit 3 And a cassette transfer device 5 for transferring a cassette between each of the wafer transfer units 1 and in the surface treatment unit 3. In FIG. 1, the control panel is not shown.

The wafer transfer unit 1 includes, for example,
The second table 12 for placing the first table 10 and the processing-dedicated cassette C ₂ for mounting a C _1, are arranged reciprocably in a horizontal direction indicated by the respective arrows. Rectangular through holes 14 and 16 are formed in the center of the first table 10 and the second table 12, respectively.
In the intermediate position between the first and second tables 12, the through holes 14, 16
An elevating plate 18 having a slightly smaller outer shape is disposed so as to be able to move up and down in the vertical direction indicated by arrows. On the upper surface of the elevating plate 18, a plurality of holding grooves into which the lower end of the wafer W is loosely inserted and which holds the wafer W are cut out. Incidentally, together with the holding groove wafer housing groove and the groove of the same pitch of the longitudinal side in the side surface of the conveyance dedicated cassette C ₁ and process only the cassette C ₂ of the lifting plate 18 is Setsu設respectively, each bottom, lift plate 18 is open so that it can penetrate. 24 in the figure
Is a transport-dedicated cassette C ₁ that has been transported from the preceding processing apparatus and loaded by an external cassette transport means (not shown).
Is a cassette loading / unloading table on which is mounted.

Further, a pair of holding arms 20 is disposed above the elevating plate 18, and the pair of holding arms 20 are supported by the support driving means 22 such that the interval between the opposing side surfaces can be expanded and narrowed, Moved or rotated. The wafer W stored in the cassette placed on the first table 10 or the second table 12 that has moved to the position of the lifting plate 18 is moved upward from the cassette by the lifting operation of the lifting plate 18, and the upward movement is performed. The held wafer W is clamped by the pair of clamping arms 20. Also, wafer holding grooves having the same pitch as the accommodation grooves of the cassettes C ₁ and C _{2 and} the holding grooves of the elevating plate 18 are cut out on the opposing side surfaces of the pair of holding arms 20, respectively.

The configuration of the wafer transfer unit is, for example,
As described in JP-A-56-44566, two cassettes may be mounted on one table.

The inside of the cassette storage shelf 2 is divided into a plurality of sections (in this embodiment, 2 steps × 3 rows = 6 sections), and one side is opened to serve as a cassette entrance. This cassette storage rack 2, stored transported dedicated cassette C ₁ or process only the cassette C ₂ of the wafer sorting unit 1 according to the progress status of the process temporarily transfers cassettes between the wafer sorting unit 1 Is performed.

Incidentally, the cassette storage shelf may be arranged on the side of the wafer transfer unit 1 in some cases. Each shelf in the cassette storage shelf is provided with an optical sensor (not shown) for detecting the presence or absence of the cassette.

Surface treatment unit 3, in this embodiment, immersion type surface treatment unit 3
Is connected to the wafer transfer section 1 at one end thereof, that is, on the processing end position side, and is constituted by a plurality of surface treatment tanks 26, 28, 30,... Filled with a required surface treatment liquid. They processing tanks 26, 28, 30, ... in the processing-dedicated cassette C ₂ are sequentially inserted, is immersed, each processing tank 26, 28, 30,
... wafer W in a state of being accommodated in the processing only the cassette C ₂ in each surface treatment liquid stored is immersed in. Reference numerals 32 and 33 in the figure are a loader unit and an unloader unit, respectively.

Next, the cassette transport section 4 includes a pair of freely movable wires 34, 34 'along one side of the surface treatment section 3 over the entire length thereof.
And the cassette mounting base plate 36 is fixed to the wires 34, 34 '. The cassette mounting base plate 36 can reciprocate between the wafer transfer unit 1 and the other end of the surface processing unit 3, that is, in the vicinity of the processing start position of the surface processing unit 3. At one end of the cassette transport section 4, a plurality of pairs of cassette holding frames 38, 40, and 42 are disposed so as to be vertically movable as indicated by arrows. An optical sensor 44 is provided at each intermediate position between the pair of holding frames 36, 40, and 42, and the presence or absence of the cassette mounting base plate 36 can be detected by the optical sensor 44. With this arrangement, when the cassette table plate 36 which carries a process dedicated cassette C ₂ travels to the left portion of FIG. 1, the optical sensor 44 detects the presence of the cassette mounting table plate 36, the platform by the detection signal Board
36 stops, then the pair of holding frames 38 rises, and the base plate 36
Floated handle only cassettes C ₂ upwards from the holding frame 38 holds the processing-dedicated cassette C _2. These holding frames and the light sensor is disposed only required number, also acts as a buffer mechanism dedicated to handling the cassette C _2.

It should be noted that the number of wires is not limited to a pair as in this embodiment, and may be one. Further, instead of the wires and the cassette mounting base plate, the cassette may be transported by a walking beam method.

The cassette transfer device 5 includes a pair of freely openable and closable cassette holding fingers 46, a holding drive means 48 for driving the cassette holding fingers 46 to open and close, a vertical movement drive means 50 for vertically moving the holding drive means 48, and a vertical movement drive means. A front-rear direction moving means 52 for moving 50 in the front-rear direction, and a left-right direction moving means for moving the front-rear direction moving means 52 in the left-right direction.
Consists of 54.

The cassette transfer device 5 allows the cassette loading / unloading table 24
The conveying dedicated cassette C ₁ between the first table 10 of the wafer sorting unit 1 and, wafer sorting unit 1 and the cassette storage rack 2 transport dedicated cassettes between the C ₁ or process only the cassette C ₂
And a cassette dedicated to processing between the wafer transfer unit 1 and the cassette transfer unit 4, between the cassette transfer unit 4 and the surface processing unit 3, and between the surface processing unit 3 and the wafer transfer unit 1.
The C ₂ can be transported, respectively. In addition, the cassette transfer device 5 includes the processing tanks 26, 28, 30,
Sequential processing may be transferred a dedicated cassette C ₂ in ....

 Next, the operation of the above device will be described.

First, the transport private cassette C ₁ accommodating the wafer W from the preceding processing unit is conveyed by the external cassette transfer means not shown, when it is placed on the cassette carrying-out Iridai 24,
Its transport dedicated cassette C ₁ is transferred from the cassette unloading Iridai 24 by the cassette transfer device 5 to the wafer sorting unit 1 of the first table 10 above. Further, if necessary, the transport private cassette C ₁ can also be temporarily stored in the cassette storage shelf 2. At this time, on the second table 12, when the processing-dedicated cassette C ₂ that do not accommodate the wafer is required to have been placed, not placed, the cassette storage rack 2
Is placed on the second table 12 by the cassette transfer device.

Then, the first table 10 mounted with the conveying dedicated cassette C ₁
Is moved to a position directly above the elevating plate 18, and then the elevating plate 18 is raised by an elevating means such as an air cylinder (not shown), so that the through-hole 14 of the first table 10 and the cassette C ₁
Passed through the opening in the bottom, lifting float a plurality of wafers W to be processed only cassette C ₁ treatment from a dedicated cassette C ₁ plate 18
To hold. Then, the elevating plate 18 is further raised to the level of the holding arm 20, and the wafer W is held between the pair of holding arms 20.

While the wafer W is being held by the holding arm 20, the elevating plate 18 descends, and when it has finished descending, the first table 10 moves to the right, and the second table 12 is replaced by the left. To the position immediately above the elevating plate 18. Processing cassette
When C ₂ stops at a position just above the lift plate 18, the lift plate 18
Is raised again to penetrate the through hole 16 of the second table 12 and the opening at the bottom of the processing cassette C _2, and the lower end portion of the wafer W held by the holding arm 20 is inserted into the holding groove of the elevating plate 18. . Then, expanding the pair of clamping Jiude 20, collectively the plurality of wafers W held by the holding groove of the lifting plate 18 upper surface, and then lowers the lift plate 18, the wafer W to the processing-dedicated cassette C in ₂ Insert and house.

Thus the wafer W is accommodated in the processing only the cassette C in _2, the second table 12 is moved from the position immediately above the lifting plate 18 to the left. Next, the processing-dedicated cassette C ₂ is held by the holding fingers 46 of the cassette transfer device 5 and transferred from the second table 12 to the cassette mounting base plate 36 at the right end position of the cassette transfer section 4 by the cassette transfer device 5. Is placed. When processing only the cassette C ₂ is placed on the cassette table plate 36, thereby running the base plate 36 to the left, the base plate 36 travels to a position of the cassette holding frame 38, by the detection signal from the photosensor 44 The base plate 40 is stopped. When the cassette mounting table plate 36 is stopped, then the holding frame 38 is raised and the holding frame 38 upward movement by processing only the cassette processing only the C ₂ to the holding frame 38 to float from the cassette table plate 36 cassette C ₂ of Will be kept and temporarily stored. Then, the cassette mounting base plate 36 travels to the original position and returns.

Next, the cassette transfer device 5 is moved to the left end,
Initially held in the cassette holding frame 42 carrying process dedicated cassette C ₂ sandwiched by sandwiching fingers 46, to transfer the processing dedicated cassette C ₂ to the surface processing unit 3 of the loader 32 by the cassette transfer device 5. Then, the required surface treatment tanks 26, 28, 30,...
The processing-dedicated cassette C ₂ is sequentially inserted into the inside, and the wafer W accommodated in the processing-dedicated cassette C ₂ is immersed in the surface treatment liquid.
A required surface treatment is performed on the wafer W.

Processing-dedicated cassette C ₂ which required surface treatment containing a wafer that has been subjected to the surface treatment section 3 is placed is transported to the unloader 33 of the surface treatment unit 3. Then, the process only the cassette C ₂ is transferred from the surface treatment section 3 of the unloader 33 by the cassette transfer device 5 to the wafer sorting unit 1 of the second table 12 above, the wafer sorting unit 1, similar to that described above by the operation, the treated wafer is transferred from the processing-dedicated cassette C ₂ to transport only the cassette C _1. After that, the cassette C _{1 for} exclusive use for transfer is moved from the wafer transfer unit 1 to the cassette loading / unloading stage by the cassette transfer device 5.
24, and is carried out by an external cassette carrying means (not shown).

As described above, unprocessed wafers which have been transported are accommodated in unloading dedicated cassette C ₁ is, once after being transferred to the processing only the cassette C _2, required surface treatment is performed,
Surface-treated processed wafer is unloaded is transferred to the reverse process from a dedicated cassette C ₂ to transport only the cassette C ₁ to the outside of the apparatus. In the meantime, each cassette is temporarily stored in the cassette storage shelf 2 as needed.

FIG. 2 shows a second embodiment of the surface treatment apparatus of the present invention, which is different from the first embodiment shown in FIG.
The cassette transfer means 5 is a cassette transfer means 1 and a cassette transfer means 5 'dedicated to the cassette storage shelf 2, a cassette transfer means 60 dedicated to the surface treatment part, and a surface treatment part loader.
This is the point that a dedicated cassette transfer means 70 is provided.

The cassette transfer means 60 dedicated to the surface treatment section includes a mechanism 62 for swinging the cassette holding fingers 61 and 61 ′, and a finger 6.
1, a lifting means 63 for vertically moving 61 ', and a horizontal moving means 64 for horizontally moving the lifting means 63 along the surface treatment unit 3.

This cassette transfer means 60 can be a cassette C ₂ is transferred from the loader 32 to the processing tank 28, 30 ... and the unloader 33, the required dipping treatment by immersing the cassette C ₂ to a predetermined processing tank .

Also, loader-specific transfer means 70, means 72 for opening and closing the cassette C ₂ pinching finger 71, 71 ', means 73 for vertically moving the closing means 72, horizontally moves the vertical movement means 73 in the longitudinal direction, pinching fingers 71, 71 'is moved horizontally from the left end position of the cassette transport section 4 to the loader 32. And horizontal moving means 74.

This loader-specific transfer means 70 can transfer cassettes C ₂ which is temporarily stored in the cassette transport part 4 to the loader 32 one set.

It should be noted that the cassette transport unit 4 is provided with a second side on the side of the surface treatment unit 3.
Needless to say, it can be provided on the surface opposite to that shown in the figure, and can be provided above the surface treatment section 3 as shown in FIG.

FIG. 4 shows still another embodiment of the surface treatment apparatus of the present invention, in which a wafer transfer section 1 'is provided adjacent to the wafer transfer section 1 and
Wafer sorting unit 1 includes a dedicated sorting unit for transferring the wafer before surface treatment dedicated to handling the cassette C ₂ from conveying dedicated cassette C _1, the second wafer sorting unit 1 'surface treated It is dedicated sorting unit for transferring the wafer to the transport dedicated cassette C ₁ from the processing dedicated cassette C _2.

In this embodiment, the lift plate 18 of the first wafer transfer unit 1 is used.
And the pair of holding arms 20 contact only the wafer before the surface treatment, and the elevating plate 18 ′ and the pair of holding arms 20 ′ of the second wafer transfer unit 1 ′ contact only the surface-treated wafer. Therefore, the surface-treated wafer is transferred to the wafer transfer unit 1
Since no contact is made with a portion that has contacted the unprocessed wafer, dust does not adhere to the surface-treated wafer, and the processing quality of the wafer is significantly improved.

Note that in each of the embodiments described above, or by concatenating device for cleaning the conveying dedicated cassette C ₁ to wafer sorting section 1, or, 1 in the immersion treatment bath of the surface treatment unit 3
Preferably a set to be able to clean the cassette C ₁ in ultrasonic cleaning or spray cleaning or the like.

Also, placing the loader 32 and the unloader 33 of the surface treatment unit 3 Conversely, a process dedicated cassette C ₂ may be transported and transferred to the contrary to the case in the above embodiment.

Further, in the above embodiment, one cassette is placed on each of the surface treatment section and the wafer transfer section. However, an apparatus configured so that two cassettes can be arranged in series may be used.

Further, an optical sensor for detecting the presence or absence of a cassette is provided at a required position, and the cassette transfer device 5 is provided.
Operation can be completely automated.

In the above embodiment, the immersion type surface treatment is described as an example. However, the type of the surface treatment may be other types such as heat treatment, and the present invention is applied to various types of wafer surface treatment apparatuses. What you get.

[Effect of the invention]

Since the present invention is configured and operates as described above, in the wafer surface treatment apparatus of the present invention, the position for loading / unloading the transfer cassette to / from the outside is only one position of the transfer cassette loading / unloading table. Therefore, it is possible to eliminate the complexity of providing a cassette loading / unloading table in each of the component devices such as the surface processing unit and the wafer transfer unit and carrying out loading and unloading individually, and simplifying the loading / unloading process. Thereby, automation of the process between the pre-processing and post-processing is facilitated. Also,
Since the transfer distance of the cassette is the shortest, the transfer procedure is optimized and the wafer is immediately transferred or stored in the stocker after the surface treatment of the wafer is completed. In addition, the quality of the surface treatment of the wafer can be improved, and the vibration and external unnecessary force applied to the wafer can be reduced as much as possible to reduce the damage to the wafer.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention and showing an entire surface treatment apparatus for a wafer. FIG. 2 to FIG. 4 are perspective views similar to FIG. 1, showing another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1 ... Wafer transfer part, 2 ... Cassette storage shelf, 3 ... Surface treatment part, 4 ... Cassette transfer part, 5 ... Cassette transfer device,
C ₁ : cassette for transport, C ₂ : cassette for processing, W: wafer.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-58-135743 (JP, A) JP-A-59-32987 (JP, A) JP-A-60-59747 (JP, A) 138046 (JP, A)

Claims (2)

(57) [Scope of request for utility model registration] 1. A wafer surface treatment apparatus using a processing cassette for accommodating a wafer to be surface-treated and a transport cassette for accommodating a wafer to be carried in and out, wherein the wafer accommodated in the processing cassette is A surface treatment unit in which a plurality of treatment tanks for performing a required surface treatment are arranged, and a treatment tank arranged along the arrangement direction of the plurality of treatment tanks and carrying a treatment cassette in the arrangement direction. A cassette transfer unit, a wafer transfer unit disposed at one end of the plurality of processing tanks arranged for transferring a wafer between a transfer cassette and a processing cassette, and a wafer transfer unit above the wafer transfer unit. Or it is arranged on the side
A cassette storage shelf capable of storing at least one of a transfer-only cassette and a processing-only cassette; and a transfer-only cassette unloading unit, which is disposed adjacent to the wafer transfer unit and on which a transfer-only cassette to be loaded and unloaded is placed. Loading, transferring at least one of the transfer cassette and the processing cassette between the wafer transfer unit and the cassette storage shelf, and between the wafer transfer unit and the processing cassette transfer unit. And cassette transfer means for transferring a processing-only cassette between the processing-only cassette transport unit and the surface processing unit, and between the surface-processing unit and the wafer transfer unit, respectively. Characteristic surface treatment equipment for wafers. 2. A wafer processing apparatus according to claim 1, wherein a transfer cassette cleaning section for cleaning an empty transfer cassette after transferring the wafer is connected to the wafer transfer section. .