JP2002319610A - Method and device for separating and storing wafers - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for separating and storing wafers, which can reduce defective wafers by preventing progress of etching which accompanies remaining of an alkaline solvent used in a polishing process and adhesion of particles from outside air and also preventing the secondary pollution of the wafer caused by the adhesion of particles brought into existence due to the breakdown, etc., of the wafer too, when separating the wafer from a top plate and storing it in a multistage carrier after polishing process. SOLUTION: In this method and device for separating and storing the wafers, the wafers separated from the top plate 9 are guided to into a tank 1, being slid on a wafer surface whereon water is flowing, and they are stored in order from upper stages within the above multistage carrier 7, capable of elevation to the top of the tank 1 from within the above tank 1 while contacting with a water level L of the above tank, and the wafers within the above multistage carrier 7 positioned on the wafer level of the above tank are showered with water.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for separating and storing a wafer, and more particularly to a method for separating and storing a wafer after a polishing process is separated from a top plate and stored in a multi-stage carrier. Method and apparatus.

[0002]

2. Description of the Related Art In the manufacture of semiconductor wafers such as single crystal silicon, single-side polishing of a wafer involves fixing the wafer to a top plate such as an alumina plate and polishing the surface of the wafer by a polishing machine. At this time, as a method of fixing the wafer to the top plate, there are a method of adsorbing by immersing the wafer on a cloth having a high coefficient of friction, a method of adsorbing under vacuum, and a method of attaching the wafer to the top plate with an adhesive such as wax. There is a bonding method. In any of these methods, it is necessary to peel the wafer from the top plate after the polishing step, and an apparatus for automatically storing the peeled wafer in a carrier is used.

[0003] In a conventional wafer separating and storing apparatus, when a wafer is separated from a top plate and automatically stored in a carrier, etching progresses due to the remaining alkaline solvent used in the polishing step, and the air from the outside air. In order to prevent particles from adhering, they are stored underwater.

FIG. 3 shows an example of a conventional wafer peeling and accommodating apparatus of the type operated in water, in which a mounting plate and a wafer guide are provided in a water tank, and FIG.
(B) is a plan view seen from above. In the wafer separating and storing apparatus, a mounting table 13 is provided in a water tank 11 filled with water and supported by a supporting column 12 inclined with respect to a water surface L. Locking member 1
4 are attached. A wafer guide 15 is provided adjacent to the mounting table 13 and slightly lower. The wafer guide 15 is mounted on the mounting table 1 described above.
3 and attached to the support column 12 by the bottom plate 16 in the same inclination direction. Further, a carrier 17 for accommodating a wafer is disposed obliquely below the wafer guide 15. The carrier 17 is supported by a carrier elevator 18 in a state where the wafer guide 15 is inclined so that the wafer guide 15 side becomes higher. Is configured.

[0005] In the separation and storage step by this apparatus, first, the top plate 19 to which the wafer W is fixed is mounted on the upper surface of the mounting table 13 and locked by the locking member 14. Then, the wafer W is peeled from the top plate 19 by a wafer peeling jig (not shown) or the like. The peeled wafer W is guided by the wafer guide 15, slides, falls in water, and is stored in the carrier 17. By repeating the above operation, a predetermined number of wafers W are stored in the carrier 17 and the carrier is lifted by the carrier elevator 18.

As described above, according to the above-described conventional apparatus,
Since the operation until the wafer is peeled and stored is all performed in water, the etching does not proceed due to the remaining alkaline solvent used in the polishing step and particles do not adhere from the outside air. Further, friction and impact due to contact with the wafer are suppressed by the resistance of the water, and damage to the wafer can be reduced.

[0007]

However, as described above, in a conventional apparatus in which a wafer is submerged together with the fixed top plate and all operations from peeling of the wafer to storage are performed in water, The wafer is
If a part of the carrier is contaminated, the contaminant diffuses into the water in the water tank, and contaminates all wafers stored in the carrier. In addition, when even one wafer is damaged during peeling or storage, particles are generated, which are diffused in water, contaminating many of the wafers on the top plate and many of the wafers already stored in the carrier. Inconvenience also occurs. Further, since the mounting table, the wafer guide, and the like are fixed in the water tank, it takes time to clean the contaminated water tank.

In order to avoid such inconvenience, the present inventors have also studied a method of storing only a carrier containing a wafer in water. Specifically, as shown in FIG. 4, there is used a wafer separation and storage apparatus which is provided with a top plate and a wafer guide outside a water tank, and in which separation and transfer of wafers are operated on water. In this apparatus, a mounting table 23 on which a top plate 29 is mounted is provided on an outer edge of a water tank 21. In addition, a wafer guide 25 that slides the wafer W separated from the top plate 29 and guides the wafer W into the water tank 22 is provided on a water surface L in the water tank 21. Further, a carrier 27 is arranged in the water in the water tank 21 so as to be inclined so that the wafer guide 25 side is higher.
7 is supported by a carrier elevator 28 that raises and lowers it. In this apparatus, the carrier 27 is a multi-stage type having a stage for accommodating the wafers W one by one, and the wafers W are sequentially accommodated from the lower stage while being lowered by the carrier elevator 28.

According to this apparatus, since the top plate 29 and the like are outside the water tank 21, it is possible to prevent the contaminants attached on the top plate 29 from diffusing into water. Further, even if the wafer W is damaged when peeled, the secondary contamination of the wafer due to particles or the like caused by the damage is already in the carrier by cleaning the water tank or the like when the damage occurs. Stays only in wafers stored and stored in water. That is, since secondary contamination on another wafer W on the top plate 29 can be prevented, as a result, the number of defective wafers is reduced.

However, in this apparatus, a large number of wafers are already stored in the carrier, and if the wafer stored in the upper part of the carrier is damaged, the large number of wafers already stored in the carrier and stored in the water. It has been confirmed that the wafers having the second contamination are still about 10 times as large as the wafers actually damaged, resulting in particle defects due to the second contamination.

[0011] Therefore, the present invention has been made to solve the above problems, and after the polishing step,
When peeling the wafer from the top plate and storing it in a multi-stage carrier, it prevented the progress of etching due to the residual alkaline solvent used in the polishing process and prevented particles from adhering to the outside air, and also caused by damage to the wafer etc. An object of the present invention is to provide a method and an apparatus for separating and storing a wafer, which can reduce the number of defective wafers by preventing secondary contamination of the wafer due to adhesion of particles and the like.

[0012]

According to a method of separating and storing a wafer according to the present invention, a method of separating and storing a wafer fixed on a top plate and storing the wafer in a multi-stage carrier is provided. The peeled wafer is guided into the water tank by sliding on the surface where the water is flowing, while contacting the water surface of the water tank, from the upper stage into the multi-stage carrier that can move up and down from the water tank to the upper part of the water tank. Water is showered on the wafers in the multi-stage carrier which are sequentially stored and located on the water surface of the water tank. According to the above method, the wafers are sequentially stored from the upper stage of the multi-stage carrier, and the stored wafers are showered. Therefore, when the wafers are separated, the wafers are attached by particles or the like generated due to breakage of the wafers. Secondary contamination can be prevented. In addition, by the showering, it is possible to prevent the progress of etching due to the remaining alkaline solvent used in the polishing step and the generation of defective wafers due to particles attached from the outside air.

It is preferable that the peeled wafer is accommodated in the multi-stage carrier in a state where 50% or more and 80% or less of the diameter of the wafer are submerged in the sliding direction. By setting the submerged surface of the wafer within the above-mentioned range, the path of the wafer in water due to the resistance of the water is small, so that the wafer can be reliably housed in a predetermined stage of the multistage carrier.

Further, according to the present invention, there is provided a wafer separating and storing apparatus for separating a wafer fixed to a top plate and storing the separated wafer in a multi-stage carrier. A wafer guide that slides and guides the wafer separated from the top plate, the multistage carrier for storing the wafer guided by the wafer guide in the water tank, and a water tank that moves the multistage carrier from inside the water tank. A carrier elevator that moves up and down to the top, and a shower nozzle that is housed in the multi-stage carrier and that showers water on wafers located on the water surface of the water tank, and the carrier elevator includes the multi-stage carrier. As the wafer is lifted, the peeled wafer comes into contact with the water surface of the water tank and rises into the multi-stage carrier. Control means is sequentially stored from, characterized in that is provided. According to the present apparatus, the multistage carrier can be moved up each time one wafer is stored, sequentially stored from the upper stage, and the stored wafer can be subjected to showering. In addition, it is possible to prevent the next contamination and also prevent the generation of a defective wafer due to the progress of etching due to the remaining of the alkaline solvent used in the polishing step and the adhesion of particles from the outside air.

The multistage carrier is supported such that the inclination angle of each stage with respect to the water surface of the water tank is not less than 5 ° and not more than 45 °, and the wafer guide is provided such that the inclination angle of the water tank with respect to the water surface is the multistage. It is preferable that the mold carrier is provided so as to be equal to the inclination angle of each stage. By setting the inclination angle within the above range, it is preferable in that the resistance received from the water when the wafer enters the water surface is adjusted, and the entry direction in the water and the storage position in the multi-stage carrier are appropriately maintained.

[0016] The shower nozzle may be symmetrical leftward and rightward of the multistage carrier toward the sliding direction of the wafer and downward from the horizontal at an angle equal to the inclination angle of each stage of the multistage carrier. It is preferable to be provided so as to be showered. With the shower nozzle having the above-described configuration, it is possible to uniformly shower the entire wafer in each stage accommodated in the multistage carrier.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing one embodiment of a wafer separation and storage apparatus according to the present invention. This device is
The present invention is characterized in that the wafers are stored sequentially from the upper stage in the multi-stage carrier and are showered on the stored wafers located on the water surface.

As shown in FIG. 1, in the wafer separating and storing apparatus according to the present invention, the top plate 9 is
Is mounted on the upper surface of the mounting table 3 which is disposed to be inclined downward toward the water surface L by a locking member (not shown) or the like. The wafer guide 5 is positioned adjacent to and slightly lower than the mounting table 3.
Are provided to be inclined downward toward the water surface L. On the exit side of the wafer guide 5 (on the opposite side of the mounting table 3), a multi-stage carrier 7 is arranged so as to be inclined downward in the sliding direction of the wafer. The multi-stage carrier 7 is supported by a carrier elevator 8. The carrier elevator 8 is operated by rollers, belts, motors, and the like, and is provided with control means capable of adjusting the height position of the multistage carrier 7 by one pitch (step interval). Each of the wafers W accommodated in the multi-stage carrier 7 and raised above the water surface is placed on the water tank 1.
Is provided with a shower nozzle 2 for showering (spraying) water.

The carrier elevator 8 sets the multi-stage carrier 7 at a step interval (usually 4.76 mm) of one pitch,
Between the time when the wafer W is stored in the predetermined stage and the time when the next wafer slides underwater, the multi-stage carrier 7
Is increased by one pitch. As a result, when the wafers W are sequentially stored in the predetermined stages, the stage in which the wafers W are stored is pulled up on the water surface L.

In the above apparatus, the wafer W is peeled off from the top plate 9 one by one using the wafer peeling jig 4. At that time, the separated wafer W
In order to reduce sliding friction and prevent drying, sliding movement is performed on the top plate 9 and then on the surface of the wafer guide 5 along the slope with running water. The running water is received in the water tank 1.

The wafer guide 5 plays a role of guiding the wafer W separated from the top plate 9 to be stored in a predetermined stage in the multi-stage carrier 7 located in the water in the water tank 1. To fulfill. The exit side of the wafer guide 5 is set at a position higher than the water surface, and the inclination angle thereof is not less than 5 ° and not more than 45 ° with respect to the water surface L. When the inclination angle of the wafer guide 5 is less than 5 °, the resistance of water when the wafer W enters the water is large,
The deflection of the path of the wafer W increases, and the multi-stage carrier 7
It is difficult to reliably store the information in a predetermined stage. On the other hand, when the inclination angle exceeds 45 °, the wafer W
However, the speed at which the wafer W is stored in the multi-stage carrier 7 is high, and the wafer W
May be damaged.

The multi-stage carrier 7 used in the above-mentioned apparatus has a structure in which a plurality of steps having an upper surface and an opening for the entrance of the wafer W are provided. In use, the wafer W sliding from the wafer guide 5 is used. Is fixed to the support base of the carrier elevator 8 in a state where it is inclined so as to be stored in a predetermined step from this opening.

The inclination angle of each stage of the multistage carrier 7 is as follows:
Is set according to the relationship with the inclination angle of the wafer guide 5,
It is preferable that the inclination angle is equal to the inclination angle of the wafer guide 5. By making the inclination angle between each stage of the multi-stage carrier 7 and the wafer guide 5 equal, the impact when the wafer W is stored in the multi-stage carrier 7 is reduced, and the storage can be surely performed.

The wafer W is stored in the multi-stage carrier 7 near the water surface L in a state where 50% to 80% of the diameter of the wafer W is submerged in the sliding direction. FIG. 2A is a schematic cross-sectional view showing a state near the water surface L when the wafer W is stored in a predetermined stage of the multi-stage carrier 7 in the above apparatus. FIG. 2B is a view showing the state of submerging the wafer W when the wafer W is stored, as viewed from the direction A in FIG. 2A. As shown in FIGS. 2A and 2B, the wafer W
In the sliding direction, in a state where the length / diameter (b / a) of the submerged diameter is 50% or more and 80% or less,
It is preferable to set so as to be stored in a predetermined stage. b / a is more preferably 50%. Said b
/ A is less than 50%, the wafer W that has slid
Cannot fully receive the resistance of the water in the water tank 1,
The impact when stored in the multi-stage carrier 7 increases,
It may be damaged. On the other hand, if the ratio b / a exceeds 80%, the path of the wafer W in the water becomes long, and the resistance of the water tends to cause a swing in the direction of the path.
May not be properly stored in a predetermined stage of the multi-stage carrier 7.

The wafer housed in the multi-stage carrier 7 and pulled up on the water surface by the carrier elevator 8 is
Water is showered by the shower nozzle 2. Thereby, by washing off the deposits such as particles generated by the damage of the wafer W due to the separation, it is possible to prevent the secondary contamination of the wafer W and also prevent the wafer from drying. Further, even if a very small amount of the alkaline solvent used in the polishing step adheres to the surface of the wafer W, it can be completely cleaned and the progress of etching can be prevented.

Further, in the above-described apparatus, even if the wafer W is damaged when peeled, the wafer W already stored in the multi-stage carrier 7 is outside the water tank 1, so that the water tank 1 There is no secondary contamination by water in the interior. Then, when the wafer W is damaged, the multi-stage carrier 7 is pulled up, the operation is temporarily suspended, and the water tank 1 containing the damaged wafer W and the water mixed with the particles generated thereby is washed or replaced. do it.

The position of the shower nozzle 2 is
Is preferably provided on the rear surface of the multi-stage carrier 7 in the sliding direction. In particular, it is preferable to install two symmetrically from the diagonally rearward so as not to hinder the course of the wafer W and to uniformly shower the wafer W. Further, the angle of the showering is set so that the wafers of each stage stored in the multi-stage carrier 7 are uniformly showered. The setting of these shower nozzles 2 is appropriately set according to the size of the wafer W, the number of stages of the multi-stage carrier 7, and the like. The material of the shower nozzle 2 is preferably made of Teflon (registered trademark) from the viewpoint of preventing contamination such as metal contamination. Further, it is preferable to cover the shower with a waterproof cover or the like in order to prevent water from splashing around the wafer separation and storage device.

Although the material of the top plate 9 to which the wafer W is attached is not particularly limited, an alumina plate or the like is usually used in the polishing process of the wafer W. In general, for attaching the wafer W to the top plate 9 such as an alumina plate,
A solution in which a wax or the like is dissolved in a solvent is used as a bonding and fixing agent.However, in order to prevent breakage such as cracking or chipping of the wafer at the time of peeling, especially when the flatness standard of the wafer is not strict, It is preferable to perform a baking process for evaporating the solvent of the wax.

Hereinafter, a method of peeling the wafer W attached to the top plate 5 and storing the wafer W in the multi-stage carrier 7 using the above-described apparatus according to the present invention will be described in detail. First, the water tank 1 is filled with water, and the multi-stage carrier 7 is fixed to the carrier elevator 8. Then, the multi-stage carrier 7 is lowered by the carrier elevator 8, and the uppermost stage is arranged such that a portion forward in the wafer entry direction is submerged. Next, when the first wafer W is peeled off from the top plate 9 using the wafer peeling jig 4 or the like, the wafer W slides along the slope with the water flowing on the surface of the top plate 9 to the wafer guide 5. . At the same time, the showering of water from the shower nozzle 2 is automatically started.

The peeled wafer W slides on the surface of the wafer guide 5 together with the water flow, and enters the water surface L obliquely from the exit side. Then, the wafer W is stored in the uppermost stage of the multi-stage carrier 7 while being in contact with the water surface L. At the same time as the storage of the first wafer W is completed, the multi-stage carrier 7 supported by the carrier elevator 8 moves up, and the next lower stage than the stage where the wafer W is stored is moved to the next stage. Stop at a position where a wafer can be stored. Water is showered by the shower nozzle 2 to the wafer W stored in the multi-stage carrier 7 and pulled up on the water surface. Next, the next separated wafer W slides toward the water surface via the wafer guide 5.

By repeating the above operation, the separation and storage of the wafers proceed sequentially. Then, when either the separation and storage of the wafer W stuck on the top plate 9 is completed or the wafer is stored in all the stages of the multi-stage carrier 7, the above operation is performed once. Suspended,
After replacing the top plate 9 and / or the multi-stage carrier 7, etc., the carrier elevator 8 and the like are arranged in the initial state.

If the wafer W is damaged when it is peeled, the multi-stage carrier 7 is pulled up, the above operation is temporarily stopped, and water containing the damaged wafer W and particles generated by the damage enters. Wash or replace the existing water tank 1. As a result, secondary contamination of another wafer W can be prevented, and post-processing when the wafer W is damaged is simplified.

In the above description, the method and apparatus for peeling and storing a wafer when the wafer is attached to the top plate, that is, when the wafer is fixed to the top plate by an adhesive method, have been described. The present invention is not limited to this case, and the same method and apparatus can be used even when fixed by an adsorption method.

[0034]

EXAMPLES Hereinafter, the present invention will be described more specifically based on examples, but the present invention is not limited to the following examples. EXAMPLE A wafer was peeled from an alumina plate having a 5-inch diameter polished wafer on one side using a wafer peeling and accommodating apparatus according to the present invention as shown in FIG. The operation of storing the wafers in the mold carrier was performed, and about 200,000 wafers were processed. Investigation of the probability of occurrence of defective wafers including the secondary-contaminated wafer during this time revealed that only defective wafers were damaged, and the probability of occurrence of defective wafers was 0.004%.
For the lots in which breakage such as cracks due to peeling occurred, the number of particles adhering to the wafer was measured using a wafer surface inspection device (WM-3: manufactured by Topcon Corporation). (≧ 0.20 μm).

COMPARATIVE EXAMPLE Using a conventional wafer separation and storage apparatus as shown in FIG. 4, the wafer was peeled from an alumina plate to which a wafer having a diameter of 5 inches and one side of which was polished was attached. An operation of accommodating in a 25-stage multi-stage carrier was performed, and about 200,000 wafers were processed. Investigation of the probability of occurrence of defective wafers including the secondary-contaminated wafer during this time revealed that the probability of occurrence of defective wafers was 0.042%. Further, for a lot in which no damage such as a crack occurred, the number of particles adhering to the wafer was measured in the same manner as in the example, and found to be 3.2 on average (≧ 0.20 μm). on the other hand,
For lots with breaks such as cracks due to peeling,
The average number of particles of wafers stored in water is 7.
In particular, the number of stages of the multi-stage carrier is 14.5 on the average in the upper and lower 5 stages around the stage where the damaged wafer is stored, which is 4 of the lots in which no damage occurred. 0.5 times.

As described above, when the apparatus according to the present invention for storing a wafer while raising the multi-stage carrier and performing showering is used, the wafer is stored while the multi-stage carrier is lowered and stored in water. It has been found that, when a wafer is damaged, particles adhering to other wafers can be reduced and secondary contamination of the wafer can be prevented as compared with the case where a conventional apparatus is used.

[0037]

As described above, the wafer peeling and accommodating apparatus according to the present invention is used in the polishing step when the wafer is peeled off from the top plate by a method combining the ascending and accommodating of the multistage carrier and the showering. In addition to preventing the progress of etching due to the remaining alkaline solvent and the adhesion of particles from the outside air, it is also possible to prevent the secondary contamination of the wafer due to the adhesion of particles and the like caused by damage, and the defective wafer in the wafer peeling and storing process. Can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing one embodiment of a wafer peeling and storing apparatus of the present invention.

FIG. 2A is a cross-sectional view showing a state near a water surface when a wafer is stored in a multi-stage carrier using the wafer separation and storage apparatus according to the present invention. FIG. 2 (b) is a view from the direction of arrow A in FIG. 2 (a), showing a state of submergence when a wafer is stored in a multistage carrier.

FIG. 3A is a schematic cross-sectional view showing an example of a conventional wafer separation and storage device. FIG. 3B is a schematic plan view of the device shown in FIG.

FIG. 4 is a schematic cross-sectional view showing an example of a conventional wafer separation and storage device.

[Explanation of symbols]

 1, 11, 21 Water tank 2 Shower nozzle 3, 13, 23 Mounting table 4 Wafer peeling jig 5, 15, 25 Wafer guide 7, 27 Multi-stage carrier 8, 18, 28 Carrier elevator 9, 19, 29 Top plate 12 Supporting column 14 Locking member 16 Bottom plate 17 Carrier L Water surface W Wafer

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Nobuyuki Sato, Inventor No. 378, Oguni-machi, Oguni-machi, Nishiokitama-gun, Yamagata F-term in the Oguni Works of Toshiba Ceramics Co., Ltd. 5F031 CA02 DA01 FA01 FA07 FA11 FA12 FA18 GA56 GA61 HA02 HA12 HA13 HA44 MA22 NA18 PA20 PA23 PA24

Claims (5)

[Claims] 1. A method for separating and storing a wafer fixed to a top plate and storing the wafer in a multi-stage carrier, wherein the wafer separated from the top plate slides on a surface where water is flowing. Guided into the water tank, and while being in contact with the water surface of the water tank, the multi-stage carriers are sequentially housed from the upper stage in the multi-stage carrier capable of ascending and descending from the water tank to the upper part of the water tank, and located on the water surface of the water tank. A method for separating and storing a wafer, wherein water is showered on a wafer in a carrier. 2. The multi-stage carrier according to claim 1, wherein the separated wafer is submerged in the sliding direction by 50% or more and 80% or less of the diameter of the wafer. 2. The method for separating and storing a wafer according to 1. 3. A wafer peeling and storing apparatus for peeling a wafer fixed to a top plate and storing the wafer in a multi-stage carrier, wherein a water tank and a wafer peeled from the top plate into the water tank are slid. A wafer guide to be guided, the multistage carrier for storing the wafer guided by the wafer guide in the water tank, a carrier elevator for elevating the multistage carrier from the water tank to the upper part of the water tank, and the multistage type. A shower nozzle for showering water is provided on the wafer positioned on the water surface of the water tank housed in the carrier, and the carrier lifter lifts the multi-stage carrier to remove the separated wafer, While being in contact with the water surface of the aquarium, a control means is provided that is sequentially stored in the multi-stage carrier from the upper stage. Peeling housing device of the wafer, characterized by being. 4. The multi-stage carrier is supported such that an inclination angle of each stage with respect to the water surface of the water tank is 5 ° or more and 45 ° or less, and the wafer guide has an inclination angle with respect to the water surface of the water tank. 4. The wafer separating and storing apparatus according to claim 3, wherein the wafer is provided so as to have the same inclination angle as each stage of the multi-stage carrier. 5. The shower nozzle is arranged obliquely rearward of the multi-stage carrier in a direction in which the wafer slides.
5. The wafer according to claim 3, wherein the wafer is provided so as to be symmetrical and to be showered downward from a horizontal direction at an angle equal to an inclination angle of each stage of the multistage carrier. Peeling storage device.