JP2006021913A - Clean stocker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a clean stocker for improving the manufacturing yield and quality of stored objects while preventing the deposition of harmful materials such as water on the stored objects such as wafers during storage and surely preventing the destruction of devices resulting from electric charge. <P>SOLUTION: The clean stocker comprises a house 10 having a carry-in port 11 and a carry-out port 12 and including a stocker crane 14 provided between a plurality of stages of shelves 13 for storing the stored objects 3, 5 and the carry-in/-out port in a travelling manner for putting the stored objects in and out of the shelves and a clean air circulating means 15 for making cleaned air flow in the house 10. In the house 10, a clean dry air supply pipe 16 is provided to be filled with clean dry air from which molecular contaminants are removed down to a level of 10 ppb or less and which has an atmospheric pressure dew point of -100°C or lower. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  TECHNICAL FIELD The present invention relates to a clean stocker for temporarily storing stored items such as semiconductor wafers that do not like adhesion of moisture and fine contaminants.

  In manufacturing plants for semiconductor substrates, glass substrates for flat panel displays such as LCD (Liquid Crystal Display), PDP (Plasma Display), EL (Electroluminescent Display), etc., the above-mentioned semiconductor wafers, glass substrates, etc. A clean stocker is provided for temporarily storing them for time adjustment and the like in the process of transporting from one manufacturing process to another manufacturing process.

  FIG. 6 shows a conventional clean stocker of this type. A plurality of shelves 2 for storing cassettes 3 are arranged on both sides of a building 1 provided with a carry-in port and a carry-out port in the front and back direction of the paper. A stocker crane (not shown) for inserting / removing the cassette 3 to / from the shelf 2 is provided between the shelf 2 and the carry-in port and carry-out port at a central portion between the shelves 2. The fan filter unit 4 for allowing the cleaned air to flow into the building 1 is provided on the rear side of each shelf 2.

Here, as shown in FIG. 7A, the inside of the cassette 3 is divided into a plurality of stages in the vertical direction by the cassette pins 3a, and a plurality of the above-mentioned wafers, etc., which are stored items, are interposed between these cassette pins 3a. 5 is stored so as not to interfere with the adjacent ones.
In addition, the upper and lower side walls of the building 1 are each provided with an intake port 6 for supplying clean air (clean air) therein, and an exhaust port 7 at the bottom.

  In the conventional clean stocker having the above configuration, clean air whose humidity is adjusted to about 45% is supplied from the air inlet 6 to the inside of the building 1 and is circulated inside while being cleaned by the fan filter unit 4. In addition, in order to control the internal temperature, a certain amount is extracted from the bottom exhaust port 7 to the outside.

  By the way, along with the recent increase in size and densification of the semiconductor wafer and the flat display glass substrate, the adhesion of moisture at the molecular level to the surface of the wafer 5 etc. in the clean stocker and the contamination of fine organic matter, etc. Material adhesion is becoming a problem.

  That is, in the semiconductor wafer and various flat display glass substrates, when moisture is adsorbed on the surface, the growth of a natural oxide film can be promoted, or a metal or an organic substance can be dissolved therein to become a new contamination source. . In particular, it is also known that when a corrosive gas comes into contact with moisture on the surface in the process chamber, gas molecules dissolve into the moisture layer and become active ions to corrode the metal surface.

  In addition, if contaminants such as fine organic substances contained in the air adhere to the wafer or glass substrate, when a metal film is formed in a later process, insulation resistance cannot be obtained, or the metal film There is a risk of peeling.

  However, in the conventional clean stocker, since clean air supplied to the interior of the building 1 from the air inlet 6 is adjusted to a humidity of about 45%, such a wafer or the like is used. 5 cannot be prevented from adhering to the surface.

  Further, particles contained in the air can be removed by the fan filter unit 4 for the time being, but contaminants such as organic substances cannot be removed. In addition, these fine pollutants are contained in the clean air supplied from the air inlet 6, and the members constituting the inner walls and shelves 2, etc. in the interior of the building 1, or cables wired in the interior Also, it is released from the insulating material over time.

  For this reason, for example, when the amount of clean air exhausted from the exhaust port 7 decreases and the amount circulated inside increases due to temperature control, the concentration of the contaminants gradually increases to the surface of the wafer 5 or the like. Adhesion may not be negligible.

  In general, when the wafer 5 or the like is transferred, as shown in FIG. 7A, a plurality of sheets are stored in one cassette 3 and transferred in a batch, but as shown in FIG. As described above, the cassette pins 3a and the wafer 5 are brought into contact with and slid by the vibration during the transfer, and the wafer 5 is charged with static electricity. For this reason, conventionally, as shown in FIG. 8, in the apparatuses A and B in each process, the above-mentioned wafer 5 is neutralized.

  However, as shown in FIG. 8, even when the static electricity is removed from the apparatus A in the previous process and becomes 0 (V), it is transported from the apparatus A to the clean stocker and is transported to the subsequent process apparatus B. At this time, since the amount of charge continues to increase, if this exceeds the allowable value X (V), there is a possibility that a discharge phenomenon will occur and the device may be destroyed before the neutralization operation is performed in the apparatus B in the subsequent process.

  The present invention has been made in view of such circumstances, and can prevent adhesion of harmful substances such as moisture to stored items such as wafers during storage, and also reliably prevent device destruction caused by charging. Therefore, it is an object of the present invention to provide a clean stocker capable of improving the production yield and quality of the stored items.

  In order to solve the above-mentioned problem, the invention according to claim 1 includes a plurality of shelves for storing stored items inside the building provided with a carry-in port and a carry-out port, and the carry-in port and the carry-out port. A clean stocker provided with a clean air circulating means for flowing clean air into the building, provided with a stocker crane that is movably provided between the shelf and for taking in and out the stored items. The above building was provided with a clean dry air supply pipe filled with clean dry air (hereinafter referred to as ultra-low dew point air) having an atmospheric pressure dew point of −100 ° C. or less in which molecular contaminants were removed to 10 ppb or less. It is characterized by this. If the flat plate member is extremely disliked by molecular contaminants, it is more preferable to use the ultra low dew point air from which molecular contaminants of 5 ppb or less have been removed.

  Here, the ultra-low dew point air is provided with a plurality of disk-shaped members having high water absorption, such as silica gel, for example, and the plurality of stages of disk-shaped members are rotated from the blower while rotating the disk-shaped members. Passing through one section of the member, the dew point is lowered in sequence, and the disk-shaped member that has absorbed moisture is dried by a known ultra-low dew point air supply device in other sections in the rotational direction by a heater or the like. Obtainable.

  According to the above ultra-low dew point air supply device, contaminants such as organic matter contained in the air are also collected and removed when passing through a disk-shaped member such as silica gel arranged in a plurality of stages. However, by installing a predetermined ULPA filter in the final stage, it is possible to obtain clean ultra-low dew point air from which molecular contaminants have been removed to 10 ppb or less.

  The invention according to claim 2 is characterized in that the building according to claim 1 is provided with an exhaust pipe for collecting the clean dry air while keeping the inside at a positive pressure. is there.

  Furthermore, the invention described in claim 3 is a soft X-ray static eliminator that neutralizes the stored matter by irradiating the stored matter with soft X-rays in the building according to claim 1 or 2. Is installed.

  The invention according to claim 4 is the invention according to claim 3, wherein the stocker crane is configured such that a carriage on which the stored item is placed on a mast erected on a base is freely movable up and down and has a vertical axis. The soft X-ray static eliminator is attached to the mast so as to irradiate the soft X-ray toward the carriage.

  According to the invention described in any one of claims 1 to 4, the ultra-low dew point air is supplied and filled from a clean dry air supply pipe, and this is further filled by a clean intake air circulation means such as a fan filter unit. Since it is made to flow into the building, the ultra-low dew point air has an atmospheric pressure dew point of −100 ° C. or less and molecular contaminants are removed to 10 ppb or less. There is no risk of contaminants such as moisture and organic matter that would be harmful to stored items. As a result, the production yield and quality of the stored items can be improved.

  Further, in the invention described in claim 2, since the exhaust pipe for collecting the ultra-low dew point air is provided while the interior of the building is kept at a positive pressure, the internal temperature control is easy as in the prior art. In addition, molecules or molecular level contaminants generated from the constituent members in the building can be discharged to the outside together with the ultra-low dew point air exhausted from the exhaust pipe. Therefore, it is possible to always keep the building in the atmosphere of the above-mentioned ultra-low dew point air and to prevent the outside air from flowing into the building because the inside is always kept at a positive pressure. it can.

  By the way, as described above, when the interior of the building is held in an atmosphere of ultra-low dew point air, the dew point is extremely low, so that static electricity is more likely to be generated in stored items than the conventional one. As a result, as shown in FIG. 8, at the time of carrying back and forth to the clean stocker, there is an increased possibility that the stored item will be discharged and damaged.

  In this regard, according to the invention described in claim 3, since a soft X-ray static eliminator is installed in the building to remove static electricity from the stored item by irradiating the stored item with soft X-rays. It is possible to prevent such adverse effects from occurring.

  Here, when performing neutralization of the above-mentioned stored items, if an ionizer that generates ions between general electrodes is used, ozone is generated when the ions are generated, or particles that become pollutants are generated due to electrode wear. However, in the invention described in claim 3, soft X-rays are used to neutralize the stored items by directly irradiating the stored items with weak X-rays and ionizing the surrounding atmosphere. Since the static eliminator is used, the above-described adverse effects can be prevented.

  Since the stored items are distributed and arranged on a plurality of shelves in the building, a large number of devices are required if the soft X-ray static eliminator according to claim 3 is provided on the shelves. This is not realistic because the device is expensive. Therefore, as the installation position of the soft X-ray static eliminator, a carry-in entrance through which all stored items pass and a carry-out exit conveyor section can be applied.

  Furthermore, since the stocker crane needs to store the stored items carried in from the entrance at various positions on the shelf, a carriage for placing the stored items on the mast usually standing on the base is provided. It is configured to be movable up and down and rotatable about a vertical axis. Therefore, if the soft X-ray static eliminator is attached to the mast as in the invention described in claim 4, various directions are directed toward the stored items on the carriage by using the lifting and rotating operations of the carriage. By irradiating with soft X-rays, the maximum static elimination effect can be obtained with the minimum number of units.

  1 to 5 show an embodiment of a clean stocker according to the present invention. This clean stocker has a moisture or molecular level on the surface of a semiconductor wafer or a glass substrate for flat display such as LCD, PDP, EL, etc. It can be applied to various stored items that do not like the adhesion of pollutants such as organic substances.

  In the clean stocker building 10, both ends in FIG. 2 are provided with an entrance 11 and an exit 12 that are opened and closed at the time of storage and retrieval of stored items, respectively, and those shown in FIG. A plurality of shelves 13 for storing cassettes 3 storing a plurality of similar wafers (stored items) 5 are arranged. Between these shelves 13, a rail 14 a extending from the carry-in port 11 to the carry-out port 12 is laid, and a stocker crane 14 for taking in and out the cassette 3 with respect to the shelf 13 is movably provided on the rail 14 a.

A fan filter unit (clean air circulating means) 15 is provided on the rear side of each shelf 13 to eject the cleaned air to the cassette 3 side and flow into the building 10.
On the other hand, a clean dry air supply pipe 16 for filling the inside of the building 10 with the ultra-low dew point air is provided at the ceiling of the building 10 located above the conveying path of the stocker crane 14.

  The supply pipes 16 are provided at a plurality of locations (four locations in the figure) along the transport path of the stocker crane 14, and all of them are derived from a single ultra-low dew point air supply device (not shown). Further, as shown in FIGS. 3A and 3B, the outer wall of the building 10 is configured by passing an outer plate 18 between frames 17 erected at a predetermined interval. In order to improve the airtightness, a packing 19 is attached to the adjacent outer plate 18, and a tape 20 is attached between these packings 19 to straddle the frame 17 and seal the gap between the outer plate 18. Yes.

  An exhaust pipe 21 is provided above the space between the rear surface side of the shelf 13 and the side wall of the building 10 to collect ultra-low dew point air while keeping the building at a positive pressure. The collected clean dry air is again returned to the intake side of the ultra-low dew point air supply device.

  As shown in FIG. 4, the stocker crane 14 is movably provided on the rail 14 a by a wheel 23 attached to the lower surface of the lower saddle (base) 22. A pair of masts 24 having substantially the same height as the shelf 13 are erected. A carriage 25 on which the cassette 3 is placed is provided along the mast 24 so as to be movable up and down and rotatable about a vertical axis as indicated by an arrow in the figure.

  Further, a soft X-ray neutralizing device 26 is provided at a substantially middle portion of each mast 24 in the height direction. This soft X-ray charge removal value 26 irradiates weak X-rays toward the cassette 3 on the carriage 25 at an irradiation angle of about 115 ° in both the vertical direction and the horizontal direction as indicated by the dotted arrows in the figure. It is attached as follows. On the other hand, when the stocker crane 14 is loaded or unloaded, the carriage 25 on which the cassette 3 is placed is temporarily moved up and down at the height position of the soft X-ray discharger 26 and rotated around its axis, A control sequence that can select non-execution is incorporated.

  In this clean stocker, the inner wall of the building 10 and the constituent members of the internal devices are all formed of a material that has good drainage and hardly generates organic matter from itself. For example, the fan filter unit 15 uses a galvanium steel plate as its casing instead of conventional stainless steel, and uses ULPA with a countermeasure against outgas as a filter.

  Moreover, about the structural member of the shelf 13 or the stocker crane 14, yellow zinc chromate plating is given to the surface, and aluminum white alumite coating is given to covers, such as an exterior panel and a control panel. Furthermore, low outgas cables are used for various cables, and low volatile grease is also used for grease.

  In the clean stocker having the above configuration, when ultra-low dew point air is supplied into the building 10 from the clean dry air supply pipe 16, the ultra-low temperature dew point air descends the transport path of the stocker crane 14 and shelves from the bottom. Go around 13 backwards. Then, the air is supplied to the cassette 3 side through the fan filter unit 15, and thus the inside of the building 10 is filled and circulated. At the same time, a part of the building 10 is recovered from the exhaust pipe 21 and reused through the ultra-low dew point air supply device while maintaining the interior of the building 10 at a positive pressure for temperature control and the like.

  Further, when the cassette 3 is carried in or out by the stocker crane 14, if necessary, the carriage 25 on which the cassette 3 is once placed is brought to the height position of the soft X-ray static elimination device 26 by the control sequence of the stocker crane 14. The wafer is moved by moving the soft X-ray static elimination device 26 while moving it up and down and rotating around the axis so that weak X-rays are directly irradiated to the wafer 5 and the like, and the surrounding atmosphere is ionized. 5 is removed.

  As described above, according to the clean stocker, the ultra-low dew point air flowing in the building 10 has an atmospheric pressure dew point of −100 ° C. or less and molecular contaminants are removed to 10 ppb or less. In addition, there is no possibility that contaminants such as moisture and organic matter which are harmful to the wafer 5 in the cassette 3 adhere during storage. As a result, the manufacturing yield and quality of the wafer 5 can be improved.

  In addition, since the exhaust pipe 21 for collecting the ultra-low dew point air is provided while the inside of the building 10 is maintained at a positive pressure, the internal temperature can be easily controlled, and contaminants are generated in the building 10 by any chance. However, it can be discharged to the outside together with the ultra-low dew point air exhausted from the exhaust pipe 21. Moreover, since the interior is always maintained at a positive pressure, the interior of the building 10 can be always maintained in an atmosphere of ultra-low dew point air, and outside air can also be prevented from flowing into the building 10. Can do.

  Furthermore, since a soft X-ray static elimination device 26 is installed in the building 10 to remove the static electricity by irradiating weak X-rays toward the wafer 5 etc., as shown in FIG. In this clean stocker, it is possible to remove static electricity when transporting to the device B in the subsequent process. Therefore, during the transport between these devices A and B, the charge amount is set to the allowable value X (V). It is possible to surely prevent the device destruction beyond.

  At this time, the soft X-ray static elimination device 26 is used to neutralize the stored item by directly irradiating the stored item with weak X-rays and ionizing the surrounding atmosphere. There is no adverse effect such as generation of ozone or generation of particles due to wear. Moreover, since the soft X-ray static elimination device 26 is attached to the mast 24 of the stocker crane 14, the soft X-ray neutralization device 26 is softly X-rayed from various directions toward the wafer or the like 5 on the carriage 25 by using the raising and lowering and rotating operations of the carriage 25. By irradiating the line, the maximum static elimination effect can be obtained with the minimum number of units.

It is a longitudinal cross-sectional view which shows one Embodiment of the clean stocker of this invention. It is a top view of FIG. It is a cross-sectional view which expands and shows the seal part of the building outdoor wall of FIG. It is a side view which shows the stocker crane of FIG. It is a schematic diagram which shows the charging state before and behind the clean stocker of this embodiment. It is a longitudinal cross-sectional view which shows the conventional clean stocker. (A) is a front view which shows the cassette in which the wafer etc. were stored, (b) is the A section enlarged view of (a). It is a schematic diagram which shows the charging state before and behind the conventional clean stocker.

Explanation of symbols

3 cassettes 5 wafers etc.
DESCRIPTION OF SYMBOLS 10 Building 11 Carry-in port 12 Carry-out port 13 Shelf 14 Stocker crane 15 Fan filter unit (clean air circulation means)
16 Clean dry air supply pipe 21 Exhaust pipe 22 Lower saddle (base)
24 Mast 25 Carriage 26 Soft X-ray neutralizer

Claims (4)

Inside the building provided with a carry-in port and a carry-out port, a plurality of shelves for storing stored items are provided between the carry-in port and the carry-out port so that the stored items can be moved in and out of the shelf. A clean stocker provided with a clean air circulating means for flowing purified air into the building,
A clean stocker provided with a clean dry air supply pipe filled with clean dry air having an atmospheric pressure dew point of -100 ° C. or less in which molecular contaminants are removed to 10 ppb or less in the building.   The clean stocker according to claim 1, wherein the building is provided with an exhaust pipe for collecting the clean dry air while maintaining a positive pressure inside the building.   The soft X-ray static eliminator which removes the static electricity of the stored matter by irradiating the soft X-ray toward the stored matter is installed in the building. Clean stocker.   In the stocker crane, a carriage for placing the stored items is provided on a mast standing on a base so that the carriage can be raised and lowered and rotatable about a vertical axis, and the soft X-ray static eliminator is disposed on the carriage side. The clean stocker according to claim 3, wherein the clean stocker is attached to the mast so as to irradiate the soft X-rays.

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