JP5528596B2 - Wafer storage device and wafer storage / immersion method - Google Patents

Description

  The present invention relates to a wafer storage apparatus for storing a wafer used in a semiconductor manufacturing process, and a wafer storage / immersion method for storing / immersing a wafer used in a semiconductor manufacturing process. A wafer storage device in which the storage jig is inclined by the inclination means for inclining the jig and the storage jig is vertically lowered and immersed in the water tank by the elevating means, and the storage jig is relatively vertical to the water in the water tank. The present invention relates to a wafer storage / immersion method including a step of lowering to a predetermined level and immersing a predetermined amount of the wafer.

  2. Description of the Related Art Conventionally, in a semiconductor manufacturing process, a technique for transporting or cleaning a wafer while storing it in a cassette and submerging it is widely known. For example, in an automatic cleaning apparatus that performs wafer cleaning to drying, a technique is disclosed in which a device forming surface is inclined by a predetermined angle to perform cleaning and drying, and the wafer is transported between processing tanks while being inclined by a predetermined angle. (For example, refer to Patent Document 1). In addition, a transfer device is also disclosed that pulls up from the processing tank while holding the pattern surface of the wafer at a predetermined angle with respect to the horizontal direction (see, for example, Patent Document 2). Furthermore, in order to prevent the wafer and the cassette from coming into contact with each other during cleaning, a technique in which the wafer is tilted and immersed is disclosed (for example, see Patent Document 3). Also disclosed is a technique for performing etching, pure water cleaning, IPA drying and the like while tilting the wafer. By tilting the wafer in this way, it is possible to suppress the wraparound of dust and the generation of watermarks from the back surface of the wafer (see, for example, Patent Document 4). Further, a technique related to a mechanism for converting a wafer from a vertical posture to a horizontal posture at the time of cleaning and drying of the wafer is also disclosed (for example, refer to Patent Document 5).

Japanese Patent No. 3167765 Japanese Patent Laid-Open No. 6-314677 JP-A-8-64570 Japanese Patent Laid-Open No. 10-177988 Japanese Patent No. 3066986

  However, the automatic cleaning apparatus disclosed in Patent Document 1 is designed to prevent the device forming surface of the wafer from coming into contact with the wafer storage jig, and stores the polished wafers one by one in the cassette. Therefore, it cannot be used for a cassette mechanism that submerges them. Furthermore, even if it can be assumed that the wafers that have been polished one by one are stored in the cassette, it is necessary to immerse all the cassettes in the water every time or lift them from the water, and the process of operating the cassettes In many cases, each wafer is stored unnecessarily. As a result, extra particles are often brought into the water, the inside of the water tank becomes dirty, and the throughput becomes very poor.

  In addition, since the transfer device disclosed in Patent Document 2 tilts the pattern surface of the wafer by a predetermined angle and pulls it up from the processing tank, it is possible to suppress the generation of watermarks. The robot cannot be transported and stored. Further, even if the wafer is tilted and pulled up, the wafer is submerged in a substantially vertical state, so that the pattern forming surface of the wafer may hit the slot and come into contact with the wafer storage jig due to the force of water. Moreover, since it has a complicated internal mechanism, when a polished wafer is stored in a cassette, the wafer may come into contact with components of the wafer storage jig.

  Moreover, although the technique disclosed in Patent Document 3 can stabilize the posture of the wafer in the cassette by tilting the wafer, it is not a cassette mechanism that can easily store the polished wafer. . Furthermore, in the technique of Patent Document 4, generation of a watermark can be suppressed, but the polished wafer can be easily stored in a small space, the slurry can be completely washed away, or a separate transfer mechanism can be used. There is a structural problem when taking out a wafer and storing it in a cassette easily. Further, in the technique of Patent Document 5, the mechanism for converting the wafer from the vertical posture to the horizontal posture becomes complicated, the space for changing the posture of the wafer increases, and the space utilization rate deteriorates. There is a problem that the inside of the tank tends to become dirty because there are many parts that operate greatly in conversion. Further, the wafers processed and transferred one by one are not structured to be submerged safely and efficiently with a small amount of movement. Further, no consideration is given to how water existing on the wafer is retreated.

  That is, the conventional wafer storage apparatus has various problems as described below in the mechanism for storing the polished wafer in a wet state. That is, when the cassette is set up vertically and lifted from the water tank, the wafers may be tilted back and forth in the slot, or the tilt of adjacent wafers may be reversed, and the adjacent wafers may be rubbed due to water tension. is there. Further, when the cassette is lifted from the water tank, when the water flows down from the wafer, a line-shaped stripe is formed and flows down, so that a striped line is formed on the wafer. Similarly, even when the wafer is tilted slightly vertically, the line where water flows down can be striped, and it remains as a watermark. May remain.

In addition, when a wafer is stored in the cassette by a robot with the cassette standing upright, the wafer is inclined in various directions, and a sufficient interval between the wafers stored in the cassette cannot be secured. Therefore, when inserting a wafer, there is a possibility that the arm of the robot may hit an adjacent wafer. Further, when the cassette is set up substantially vertically, the wafer must be submerged in the water tank between the time when one wafer is inserted and the time when the next wafer is inserted, but the diameter of the wafer is about 300 mm. In this case, it is necessary to raise and lower the wafer by about 300 mm every time in order to submerge the wafer. At this time, since the ascending / descending distance of the wafer is long, work time is lost. In addition, since all the wafers are repeatedly raised and lowered from the water tank, a line where water flows down is formed on the wafer each time, and as a result, a very large number of watermarks may be formed.

In addition, when the cassette containing the wafer is horizontally lifted, the wafer may swim in the slot due to the surface tension of water, and the wafer surface may be rubbed against the guide groove of the cassette and the wafer may be damaged. Furthermore, when the cassette is leveled and the wafer is submerged in the water tank as it is, the direction in which water enters the wafer varies in various directions for each wafer, which may cause the wafer to swim in the guide groove of the cassette. In addition, the wafer surface may rub against the cassette and the powder may spread to contaminate the water in the water tank. Further, since it is not determined from which part the water flows out on the wafer, the water mark is in various states depending on the wafer. In particular, there is a portion where water accumulates between the guide groove of the cassette and the wafer, and a watermark may be formed there. Further, when the wafer is pulled up, the water adhering to the back surface of the wafer may flow down onto the lower wafer, and the water may form a watermark on the lower wafer.

  Therefore, in the process of submerging and transporting the wafer after polishing, a technical problem to be solved arises so that a watermark is not formed or scratched on the surface of the wafer. It is an object of the present invention to provide a wafer storage device, a wafer storage method and a dipping method that solve this problem.

The present invention has been proposed in order to achieve the above object, and the invention according to claim 1 is a storage jig for storing the wafer horizontally in a wafer storage apparatus for storing a polished wafer. An inclination means for inclining the storage jig by a predetermined angle, a water tank for immersing the wafer stored in the storage jig, and the storage jig in which the inclination angle is maintained at a predetermined angle by the inclination means. Elevating means for elevating and lowering the tool relative to the water in the water tank while maintaining the inclination angle at the predetermined angle, and the elevating means causes the storage jig to be inclined. With the means, the wafer storage opening at the front of the storage jig is placed at a high position and the storage jig is tilted by a predetermined angle, and is lowered in the vertical direction relative to the water in the water tank. And The present invention provides a wafer storage apparatus in which a predetermined amount of wafer is immersed.

According to such a configuration, the wafer is prevented from being lifted by buoyancy against water by immersing the wafer in water while maintaining a predetermined angle of inclination, and the wafer may come into contact with the periphery of the cassette and damage the wafer. There is no.
In addition, the surface tension of the water swells at the outer periphery of the wafer due to the surface tension of the water, and there is a possibility that the water may invade the wafer surface from a random direction at the same time. Can do.
Further, the lifting means raises the storage jig from the water tank while maintaining the tilt angle at a predetermined tilt angle, so that water gently slides down from the wafer surface.

  The invention according to claim 2 is a wafer storage / immersion method for storing a wafer and immersing it in water, the step of horizontally storing the wafer in a storage jig, and the storage jig storing the wafer, The step of inclining the wafer storage opening by a predetermined angle with a high position, and the storage jig maintaining the predetermined inclination angle is lowered relative to the water in the water tank in the vertical direction. And a step of immersing a predetermined amount of the wafer.

According to such a wafer storage / immersion method, the wafer storage opening is inclined at a predetermined angle with a high position, and while maintaining the immersion state, the wafer is lowered in a vertical direction relative to the aquarium water to place the wafer. Since the fixed immersion is performed, the wafer can be gradually infiltrated and immersed in the water, so that the operation can proceed smoothly.
Moreover, when it rises, water slowly recedes from the wafer surface. Thereby, water does not remain between wafers, and the wafer can be taken out with good water drainage. Further, when the storage jig is raised, the wafer swims toward the opening, and the wafer does not spill out from the storage jig.

According to the first aspect of the present invention, the storage jig is inclined by a predetermined angle with the wafer storage opening at the front portion of the storage jig being at a high position by the tilting means, and the storage jig is tilted by the lifting means. The wafer is lowered in the vertical direction relative to the water in the water tank and the wafer is immersed in a predetermined amount. Prevents the wafer from coming into contact with the periphery of the cassette and damaging the wafer.
In addition, the surface tension of the water swells at the outer periphery of the wafer, and there is a risk that the water may invade the wafer surface from a random direction all at once, which can also be avoided, making the wafer stable, The wafer storage operation can be carried out smoothly.
Further, when the storage jig is raised from the water tank, water gently flows down from the wafer surface, so that formation of a watermark on the wafer surface can be suppressed.

According to the second aspect of the present invention, the step of horizontally storing the wafer in the storage jig, and the step of inclining the storage jig storing the wafer by a predetermined angle with the wafer storage opening at a high position. And the step of lowering the storage jig maintaining the predetermined inclination angle in a vertical direction relative to the water in the water tank and immersing the wafer in a predetermined amount, the wafer storage opening is located at a high position. The storage jig that maintains the predetermined inclination angle while being inclined by a predetermined angle is lowered in a vertical direction relative to the aquarium water so that the wafer is immersed in a predetermined amount, so that the wafer is inclined at a predetermined angle. By immersing in water while maintaining the angle, the wafer is prevented from floating due to buoyancy against water, and the wafer contacts the periphery of the cassette and damages the wafer. It is possible to avoid the possibility that say.
In addition, since the storage jig is tilted so as to raise the wafer storage opening of the storage jig and immersed in the water tank, it is possible to prevent the water from draining well and causing a watermark when the wafer is taken out of the water tank. It is.

The wafer storage apparatus which concerns on the Example of this invention comprised in the wet cassette station is shown, (a) is a top view, (b) is a side view. The explanatory view which shows the state which accommodates the wafer after grinding | polishing in the cassette of a wafer storage apparatus in the wafer storage apparatus shown in FIG. Explanatory drawing which shows the state which inclines the wafer storage apparatus in which the wafer was accommodated in the water tank. The flowchart which shows the flow of the process from the robot conveyance of a wafer to submergence in the wafer storage apparatus of this invention. It is a figure for demonstrating the behavior of the water etc. with respect to the wafer at the time of submergence, (a) is a figure which shows the aspect which immerses a wafer in water in a horizontal state, (b) is underwater in the state of (a). The figure which shows the state which water rises in the outer peripheral part of a wafer by the surface tension of water when it is immersed in (c), the figure which shows the state which immerses the wafer while inclining, (d) is the state of (c) The figure which shows that water permeates the surface part of a wafer gradually when it is made to immerse in water by. The wafer storage apparatus of this invention WHEREIN: The flowchart which shows the flow of a process until it pulls out a wafer from a submerged state. It is a figure for demonstrating the behavior of the water etc. with respect to a wafer at the time of pulling up from a submerged state, (a) is a figure which shows the aspect which pulls up a wafer in an inclined state, (b) is when pulling up a wafer in the state of (a) The figure which shows that water slides down on the wafer surface gently, (c) is a figure which shows the aspect which pulls up a wafer in a horizontal state, (d) is water on a wafer when a wafer is pulled up in the state of (c). The figure which shows that water accumulates between upper and lower wafers, and (e) is a figure which shows the aspect which pulls up a wafer in a steep inclination state.

  The present invention provides a wafer storage for storing a polished wafer in order to prevent the wafer surface from being damaged or damaged in a process of submerging and transferring the wafer after polishing the wafer. In the apparatus, a storage jig for storing the wafer, a tilting means for tilting the storage jig in which the wafer is inserted by a predetermined angle, a water tank for submerging the wafer stored in the storage jig, and a tilt Lifting and lowering means for raising and lowering the storage jig inclined by the means relative to the water in the aquarium, and the storage jig with the wafer storage opening at the front portion of the storage jig placed at a high position by the inclination means. The tool is inclined by a predetermined angle, the storage means is lowered in a vertical direction relative to the water in the water tank by the lifting means, and the wafer is immersed in a predetermined amount. Through Rukoto is obtained by achieved by providing a wafer housing unit for housing the wafer.

  Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to FIGS. In FIG. 1, reference numeral 1 denotes a wet cassette station, wherein FIG. 1 (a) is a plan view and FIG. 1 (b) is a side view.

  In FIG. 1, the wet cassette station 1 is provided with two sets of wafer storage devices 2, and both wafer storage devices 2 have the same configuration. The wafer storage device 2 includes a cassette (wafer storage jig) 4 for storing the polished wafer 3, a water tank 5 for submerging the wafer 3 stored in the cassette 4, and one wafer 3 at a time. 4 includes a transport mechanism 6 for storing the cassette 4, a cassette lifting / lowering mechanism (lifting / lowering means) 7 for raising / lowering the cassette 4 with respect to the water in the water tank 5, and an inclination means 8 for tilting the cassette 4 by a predetermined angle.

  As such a cassette 4, a stable cassette 4 that does not float even when immersed in water is used. For example, a Teflon (registered trademark) cassette 4 made of PTFE, PFA, or the like is desirable.

  The cassette elevating mechanism 7 elevates and lowers the cassette 4 by a servo motor and ball screw mechanism, and the elevating speed at this time can be varied at a speed of 5 to 30 mm / sec. The tilting means 8 can tilt the cassette 4 by a predetermined angle by the mechanism of the air cylinder, but can tilt the cassette 4 by a servo motor.

  Although not shown in FIG. 1, the wafer storage device 2 is inactive as a drain valve for draining water from the water tank 5, a publishing function attached to the pop-up prevention means of the drain valve, or a sealed container. It has a function to fill gas and IPA gas. Further, the wafer storage device 2 includes a nozzle bar (not shown) to prevent the wafer 3 from swimming forward, and has a function of flowing water from the nozzle bar to wash away the slurry on the surface of the wafer 3. Yes. Further, the wafer storage device 2 is configured to perform a stopper function of the nozzle bar, or to set the water level of the water tank 5 by one wafer 3 below the running water cleaning portion.

Next, a mechanism for immersing the wafer storage apparatus 2 in the water tank 5 while tilting it will be described.
FIG. 2 is an explanatory view showing a state in which the polished wafer 3 is stored in the cassette 4 of the wafer storage apparatus 2 in the wafer storage apparatus 2 shown in FIG. FIG. 3 is an explanatory diagram showing a state in which the wafer storage device 2 storing the wafer 3 is tilted and submerged in the water tank 5. 2 and 3, the left side of the drawing is a wafer storage opening of the cassette 4 for taking in and out the wafer 3.

  As shown in FIG. 2, the cassette 4 is stored inside the cassette table 4a. However, when the polished wafer 3 is stored in the cassette 4, the cassette table 4a and the cassette 4 are placed in a horizontal state. . At this time, the cassette stand 4 a and the cassette 4 are placed above the water surface of the water 5 a inside the water tank 5. In such a state, the wafers 3 after polishing are stored one by one in the cassette 4 by the transport mechanism 6.

  When all the wafers 3 are stored in the cassette 4, as shown in FIG. 3, the cassette stand 4a and the cassette 4 are tilted by the tilting means 8 (see FIG. 1) and then the cassette lifting mechanism 7 (see FIG. 1). As a result, the cassette table 4 a and the cassette 4 are submerged in the water 5 a inside the water tank 5. The wafer 3 may be cleaned in a state where the cassette table 4 a and the cassette 4 are submerged in the water tank 5. Also, when the cassette table 4 a and the cassette 4 are pulled up from the water tank 5, the cassette table 4 a and the cassette 4 are pulled up with the tilting means 8 tilted.

  At this time, it is desirable that the inclination angle by which the inclination means 8 inclines the cassette table 4a and the cassette 4 is in the range of 1 ° to 20 ° with respect to the vertical axis of the water surface of the water 5a in the water tank 5.

  That is, as shown in FIG. 2, the polished wafer 3 is stored in a horizontal state in a predetermined portion in the cassette 4 by the transfer mechanism 6, and after the wafer 3 is stored, the wafer storage opening of the cassette 4 is set as the front surface. The front surface of the cassette 4a and the cassette 4 are inclined by a predetermined angle (1 ° to 20 °) by the tilting means 8. Then, the cassette lifting / lowering mechanism 7 (see FIG. 1) lowers the cassette base 4a and the cassette 4 into the water 5a in the water tank 5 and immerses them by a predetermined amount (for example, an interval corresponding to one wafer 3). The wafer 3 is cleaned.

  Next, the flow of processing from when the polished wafer 3 is transported by robot until it is submerged in the water tank of the wafer storage device will be described with reference to the flowchart of FIG. 4 and FIGS. FIG. 4 is a flowchart showing the flow of processing from wafer transfer to submergence in the wafer storage apparatus of the present invention, and FIGS. 5A to 5D illustrate the behavior of water and the like with respect to the wafer during submersion. FIG.

  First, the cassette 4 stands by horizontally on the water tank 5 (step S1). Next, the wafer (transfer mechanism 6) inserts the wafer 3 into the slot of the cassette 4 (step S2). Further, the front opening (wafer storage opening) of the cassette 4 is slightly raised and inclined backward (step S3). Then, the wafer 3 in the cassette 4 is slowly immersed in the water tank 5 (step S4). In this way, the cassette 4 is lowered into the water tank 5 by one slot at a time.

  That is, when the wafer 3 is immersed in water in a horizontal state (FIG. 5A), the wafer 3 is lifted by the buoyancy of water, and the surface of the wafer 3 may come into contact with the periphery of the cassette 4 to damage the wafer 3. . In addition, the surface tension of the water causes the water to swell at the outer peripheral portion of the wafer 3, and the water may enter the surface of the wafer 3 from a random direction all at once (FIG. 5B).

  Therefore, in order to eliminate such a problem, the wafer 3 is submerged in the water tank 5 while being inclined (FIG. 5C), so that the direction in which water enters the wafer 3 is from the front opening side of the cassette 4 to the rear surface. It becomes a certain direction to. Furthermore, since the inclination angle of the wafer 3 is gentle, 1 ° to 20 °, water slowly enters the surface portion of the wafer 3, so there is no possibility that the wafer 3 will float (FIG. 5D). Further, since the water level rises along the groove of the cassette 4, the water smoothly rises onto the wafer 3. As a result, the surface can be cleaned cleanly without damaging the wafer 3.

  Next, the flow of processing when the wafer 3 is lifted from the state stored in water and taken out will be described with reference to the flowchart of FIG. 6 and FIGS. 7A to 7E. FIG. 6 is a flowchart showing the flow of processing from the submerged state until the wafer is lifted and taken out in the wafer storage apparatus of the present invention, and FIGS. 7A to 7D show water and the like for the wafer when it is lifted from the submerged state. It is a figure for demonstrating a behavior.

In the flowchart of FIG. 6, the wafer 3 is cleaned and stored in an inclined state in water (step S11). The cassette lifting mechanism 7 slowly raises the cassette 4 in an inclined state (step S12). In the ascending process, water on the surface of the wafer 3 slides gently from the front side to the rear side of the cassette 4 (step S13). When the wafer 3 rises from the water, the cassette 4 is leveled by the tilting means 8. At this time, only the wafer 3 to be taken out is positioned higher than the water, and the next wafer 3 is kept stored in the water (step S14). The wafer 3 placed on the water is grasped by the robot (conveyance mechanism 6) (step S15). The wafer 3 held by the robot is transferred to the next process as it is (step S16).

  As described above, when the wafer 3 is pulled up from the submerged state, the wafer 3 is brought into a gentle inclined state (FIG. 7A), so that the water on the surface of the wafer 3 is the water in the retreating water tank 5. They slowly slide together as if dragged to the surface (FIG. 7B). Thereby, a watermark is not formed on the surface of the wafer 3. Further, a large force is not required for lifting the wafer 3. Then, after the wafer 3 is pulled up on the water, the wafer 3 is placed in a horizontal state so that the robot can be easily taken out and transported to the next process.

  On the other hand, if the wafer 3 is placed in a horizontal state when the wafer 3 is pulled up from the submerged state (FIG. 7 (c)), the direction in which the water flows on the wafer 3 cannot be determined. Marks may be formed in various states. In addition, since water accumulates on the wafer 3 and water accumulates between the upper and lower wafers 3 (FIG. 7D), a large force is required to pull up the wafer 3.

  Further, as shown in FIG. 7E, when the wafer 3 is sharply inclined when the wafer 3 is pulled up from the submerged state, the force of retreating water as a group on the surface of the wafer 3 becomes difficult to work. In addition, a streak line may be formed on the surface portion of the wafer 3 from which water has flowed down. Further, since a very long operating range is required for lifting the wafer 3, it is not suitable for lifting the wafers 3 one by one.

  The method of relatively lifting the cassette 4 in which the wafers 3 are stored from the water is not limited to the case using the cassette lifting mechanism 7, and may be a method of draining the water in the water tank 5.

  As described above, the wafer storage apparatus of the present invention can efficiently store wafers that are polished and transported at regular intervals. Further, since the wafer storage apparatus of the present invention does not use a complicated mechanism, it is easy to access other transfer mechanisms. Furthermore, according to the wafer storage apparatus of the present invention, the wafer can be submerged efficiently without large operation after the wafer is stored. At this time, since the posture of the wafer is stable, there is no possibility that the wafer will rub against the cassette.

  Also, according to the wafer storage device, the wafers can be stocked sequentially in a space-saving manner, and the upper wafer does not bring droplets to the lower wafer, so there is a possibility that a watermark is formed on the surface of the wafer. Absent. In addition, the wafer can be efficiently stored and immersed and washed, and then the wafer can be sent out to the transport mechanism in order, so that the wafer is not frequently taken in and out of the water tank at the time of transport. Soaking and cleaning can be performed in the state.

  Further, when the wafer is stored substantially vertically in the cassette, the streak line and the water mark that are noticeable when water flows down when the water repellent surface is used when draining water can be eliminated. Further, when the wafers are stored in the cassette, it is possible to prevent the intervals between the wafers from varying and the wafers from being rubbed. Further, the wafers can be sequentially stored in the cassette and submerged without repeatedly taking out and taking out the wafers from the water tank. At this time, when the wafer is immersed, the wafer surface can be gently immersed without hitting the cassette. Further, when the wafer is taken out from the immersed state, the water slowly moves back on the wafer surface, so there is no possibility that a watermark is formed.

  The present invention can be variously modified without departing from the spirit of the present invention, and the present invention naturally extends to the modified ones.

1 Wet cassette station 2 Wafer storage device 3 Wafer 4 Cassette (storage jig)
4a cassette stand 5 water tank 6 transport mechanism 7 cassette lifting mechanism (lifting means)
8 Inclination means

Claims (2)

In the wafer storage device that stores the polished wafer,
A storage jig for storing the wafer horizontally;
Tilting means for tilting the storage jig by a predetermined angle;
A water tank for submerging the wafer stored in the storage jig;
Elevating means for raising and lowering the storage jig whose inclination angle is maintained at a predetermined angle by the inclination means relative to the water in the water tank while maintaining the inclination angle at the predetermined angle ; With
In the state in which the storage jig is tilted by a predetermined angle with the storage jig being tilted by a predetermined angle with the elevation means and the wafer storage opening at the front of the storage jig being at a high position by the tilting means. Lower it vertically relative to the water,
A wafer storage apparatus that immerses a predetermined amount of the wafer. In the wafer storage / immersion method in which the wafer is stored and immersed in water,
A step of horizontally storing the wafer in a storage jig;
The step of tilting the storage jig storing the wafer by a predetermined angle with the wafer storage opening at a high position;
The step of immersing the wafer in a predetermined amount by lowering the storage jig maintaining the predetermined inclination angle in a vertical direction relative to the water in the water tank;
A method for storing and immersing a wafer, comprising:

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