JP2005028846A - Method of and device for producing wafer storage container - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of and a device for producing a wafer storage container by which particle deposition onto the container can be prevented even in a polluted environment, a particle level after washing is stabilized, and also particle deposition onto the wafer is reduced to obtain the wafer having a stable quality. <P>SOLUTION: In this method, the container for storing a semiconductor wafer is produced while discharging the container during its production. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a container for housing a high-purity semiconductor material, and more particularly to a container molding apparatus and method.

  Conventionally, a method for manufacturing a silicon wafer used as a semiconductor substrate material used for a memory device or the like is generally a single crystal ingot using a Czochralski (CZ) method, a floating zone (FZ) method, or the like. And a wafer manufacturing (processing) process in which the single crystal ingot is sliced and at least one main surface is processed into a mirror surface. The wafer that has undergone such a process is shipped to a device manufacturing process (device company), and an element is formed on the wafer.

  In the wafer manufacturing (processing) process, a single crystal ingot is sliced to obtain a thin disk-shaped wafer, and the outer periphery of the wafer is chamfered to prevent cracking and chipping of the wafer obtained by the slicing process. A chamfering step, a lapping step for flattening the wafer, an etching step for removing processing distortion remaining on the chamfered and lapped wafer, a polishing step for mirror polishing the wafer surface, and a polished wafer And a cleaning step of removing the abrasive and foreign matter adhering to the substrate. The wafer processing step is a main step, and other processes such as a heat treatment process are added, the same process is performed in multiple stages, and the order of processes is changed. The mirror-polished wafer (sometimes called PW) is then subjected to quality inspection, etc., and the wafer is placed in a wafer storage box in units of about 25 sheets, wrapped in a laminate bag, etc., and placed in cardboard. Then shipped to a device company (device process; usually a separate company).

  A mirror-polished wafer (the final product of a wafer processing manufacturer) also has a problem of adhesion of a small amount of dust. Normally, finishing cleaning, inspection, and wafer boxing are handled in a clean room.

  As a wafer storage container (hereinafter also referred to as a storage box or simply a container), for example, a structure as shown in FIGS. 9 and 10 is known. In the figure, a wafer storage container 12 includes a container main body 14 for storing a wafer and a lid body 16 for closing an upper opening of the container main body 14. A substrate storage cassette 18 for storing a plurality of wafers is mounted in the container body 14 as shown in FIG. Reference numeral 20 denotes a gasket for improving the sealing performance attached to the peripheral portion of the upper opening of the container body 14, and 22 denotes a substrate holder attached to the upper side of the substrate storage cassette 18 and supporting the wafer.

  In addition, as shown in FIG. 11, the manufacturing method of the container for storing the wafer generally includes a raw material charging step (step 100) in which raw material pellets, which are raw materials of the container, are placed in a raw material supply tank (raw material supply unit). , A molding process for plasticizing and melting the container and supplying the mold to the mold to mold the container (step 102), an inspection and assembling process for the molded container (step 104), and packaging the container for shipping It is manufactured in the order of the packaging and packaging process (step 106). The above steps are the main ones. In the inspection and assembling process, an appearance inspection (visual and palpation) is performed for abnormalities in molding (particularly, contamination of foreign matters called “kneading”), and particle inspection of the container itself is performed. Since this inspection process takes a considerable time with respect to the molding speed, temporary storage called a storage process may be performed between the molding process and the inspection process. In addition, a cleaning process for cleaning the container may be added if necessary.

  In the product wafer after mirror finishing the wafer, it is important that no particles exist on the surface. Particles are considered to adhere depending on how the wafer is handled and the environment. Such a container for storing a wafer is washed and used in advance before storing the wafer. Depending on the particle level after molding of the container, the container is cleaned before filling the wafer (before use). However, it may not be able to be removed, and the particle level in the container after cleaning may not be stable.

  In addition, if a molded product with many particles is cleaned by using a cleaning method / cleaning device that is cleaned in a cleaning tank, particles in the cleaning tank are increased, which may cause re-adhesion problems. There was sex. Particles adhering to such a container may be bad and lead to problems in the device process. Therefore, it is desired that the number of particles adhering to the container at the time of manufacturing the container is as small as possible.

  In order to improve the particle level after molding, it is conceivable to improve the cleanliness, but to improve the cleanliness, a certain amount of equipment investment is required and the production cost is excessive. .

  The present invention can prevent particles from adhering to a container even if the environment is contaminated, stabilize the particle level after washing, and reduce the amount of particles adhering to the wafer to obtain a stable quality wafer. It is an object of the present invention to provide a manufacturing method and a manufacturing apparatus for a wafer storage container which can be used.

  Conventional storage boxes for semiconductor wafers are mainly manufactured using thermoplastic resins such as polypropylene (PP) and polycarbonate (PC) as main raw materials. It was found that the container with such a material has a very large electrostatic charge immediately after molding. In other words, it has been found that there is a phenomenon in which particles in the environment adhere to the container when the container is charged during the manufacture of the container.

  Accordingly, in order to solve the above problems, a first aspect of the method for manufacturing a wafer storage container according to the present invention is a method for manufacturing a container for storing a semiconductor wafer, which is manufactured while removing electricity from the container. It is characterized by that. A second aspect of the method for manufacturing a wafer storage container according to the present invention is a method for manufacturing a container for storing a semiconductor wafer, wherein the container is molded while removing electricity in the container forming step. To do.

  In particular, if the container is molded in an environment such as a clean room, the adhesion of particles to some extent can be reduced without worrying about the charging of the container. However, the indoor environment of the current molding process is an environment in which the degree of cleanliness is not so controlled, and the number of particles adhering to the container immediately after molding is considerable. In particular, even if the box itself is cleaned before use, particles may remain without being completely removed.

  In the method of the present invention, a static elimination mechanism (a static eliminator) is installed in a container molding machine, and the amount of charge on the container immediately after molding is kept small. In addition, a static eliminator is installed in the inspection process that is likely to generate static electricity.Measure the amount of charge in each process in advance, identify the location where static electricity is likely to be generated, install the static eliminator at an appropriate position, and eliminate static electricity. While producing the container.

  At this time, if the material of the container for housing the semiconductor wafer is polypropylene resin (PP) or polycarbonate resin (PC), the effect is great. Polyolefin-based elastomers and polyester-based elastomers are also used as parts for forming the container, but polypropylene resins and polycarbonate resins are easily charged, and containers that currently contain large semiconductor substrates (for example, silicon wafers with a diameter of 300 mm) ( Carriers, transport boxes, shipping boxes, storage boxes, etc.) are mostly made of polycarbonate resin, and it is important to eliminate static electricity when manufacturing such containers. .

  A first aspect of a wafer storage container manufacturing apparatus according to the present invention is an apparatus for molding a container for storing a semiconductor wafer, and is characterized in that a static elimination mechanism is provided for neutralizing the container. According to a second aspect of the wafer storage container manufacturing apparatus of the present invention, a mold for molding a container for storing a semiconductor wafer, a supply unit for supplying raw material pellets as a raw material of the container, and the raw material An injection molding apparatus having an injection unit for supplying a resin obtained by plasticizing and melting pellets to a mold, wherein a static eliminator is provided near the mold for molding the container.

  By using such an apparatus, the adhesion of particles at the molding stage can be significantly reduced.

  According to the present invention, it is possible to prevent adhesion of particles to the container even if the environment is contaminated to some extent by performing resin molding and inspection while taking measures against static electricity (static elimination) in the process of manufacturing the container. it can. As a result, particle contamination in the cleaning process of the container before use can be minimized, and the particle level after cleaning is also stabilized. The amount of particles originally attached to the container can be reduced, and the wafers of stable quality can be reduced by reducing particle adhesion on the wafer caused by moving from the container to the wafer. Can be supplied.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the accompanying drawings. However, the illustrated examples are illustrative only, and various modifications can be made without departing from the technical idea of the present invention. .

  The manufacturing process of the wafer storage container of the present invention will be described. FIG. 1 is a flowchart showing an example of the order of steps in the method for manufacturing a wafer storage container according to the present invention. A manufacturing method of a storage container for storing semiconductor silicon and the like generally includes a raw material charging step (step 100) in which raw material pellets, which are raw materials of the container, are placed in a raw material supply tank, and a resin obtained by plasticizing and melting the container A molding process (step 102) for molding the container in a charge-removed state, an inspection and assembly process (step 104) for the container, and a packaging and packaging process (step 106) for packaging the container for shipping. Manufactured in order. The process sequence of the method for manufacturing the wafer storage container of the present invention shown in FIG. 1 is the same as the process sequence of the conventional method shown in FIG. 11 except that the molding is performed in a static elimination state. This is manufactured by melting a pellet-shaped raw material for each member for forming a container and injection-molding it into a mold suitable for the shape of the member.

  In addition, it is preferable to manufacture while discharging the container through the entire manufacturing process of the container from the raw material charging process to the packaging process. However, it is not always necessary to neutralize the whole, and the container may be neutralized particularly in a process in which static electricity is easily charged. For example, it may be performed in a molding process, an inspection assembly process, or the like. In particular, the influence of particles adhering to the container immediately after molding is large, and implementation in the molding process is effective. Therefore, the method of the present invention is particularly characterized in that the container is molded while the container is neutralized (the container is molded in a neutralized state). In addition, in order to form the container while removing electricity from the container, for example, in the forming process, the entire injection molding apparatus can be removed from the raw material melting stage until the molded product is taken out. In particular, in the present invention, it is not necessary to remove static electricity continuously or in the whole apparatus, and a static eliminator is provided to remove electricity near the mold part for molding the container, and the container immediately after molding, particularly the moment when the mold is opened. It is important that the container is manufactured (molded) so as to eliminate static electricity.

  Then, the manufacturing method of the wafer storage container of this invention is demonstrated. FIG. 2 is a perspective explanatory view showing an embodiment of the wafer storage container manufacturing apparatus of the present invention. In FIG. 2, reference numeral 32 denotes a wafer storage container manufacturing apparatus according to the present invention. The apparatus 32 according to the present invention includes a raw material supply unit (hopper) 38 for supplying the raw material resin pellets 36 as the raw material resin of the wafer storage container 34 and a mold 40 for molding the wafer storage container, as in the known injection molding apparatus. , And an injection unit portion 42 for supplying a resin 36 a obtained by plasticizing and melting the raw material pellets 36 to the mold 40. The injection unit 42 is composed of a cylinder part 42a for melting the pellet-shaped raw material 36 introduced from the raw material supply part 38 and a screw means (injection means) for injecting the molten raw material pellets into the mold 40. (FIGS. 4-8).

  In the drawing, an example in which the injection unit 42 is disposed in a base body 43 is shown. As the mold 40, any known configuration can be used, but in the illustrated example, an example of a two-sheet configuration mold is shown. That is, the mold 40 includes a cavity mold 40a having a cavity 44 and a core mold 40b having a protrusion 46 corresponding to the cavity 44 and disposed so as to be able to contact with and separate from the cavity mold 40a. It is configured. Reference numeral 48 denotes a mold support for supporting the core mold 40b. The mold support 48 is provided with a support rod 52 having a static eliminator 50 attached to the tip thereof so as to surround the core mold 40b. Reference numeral 54 denotes a transfer robot for taking out the molded container 34. By using such an injection molding machine with the static eliminator 50, that is, the device 32 of the present invention, charging of the container 34 is prevented during molding, and adsorption of particles in the environment is reduced. In addition, although the example which attached the static eliminator 50 to the metal mold | die support body 48 was shown in the said example, arrangement | positioning of the static eliminator 50 is not restricted to the said example, The metal mold | die 40 (especially core metal mold | die 40b) by which a container is shape | molded. It may be attached in any shape as long as it is arranged in the vicinity and the container immediately after molding can be neutralized.

  The static eliminator 50 may have any principle. For example, it is preferable to use a static eliminator of a type that can eliminate static electricity in a short time and at a certain distance from the object. For example, a so-called “ionizer” of a corona discharge type or a static eliminator called “electric field line radiation neutralizer” may be used. What is necessary is just to perform static elimination by setting the distance between the electrodes of the static eliminator and the distance to the container (object) to be fixed.

  The case where the container 34 is injection-molded using the above-described device 32 of the present invention will be described with reference to FIGS. FIG. 3 is a flowchart showing the procedure of injection molding of the wafer storage container. 4 to 8 are schematic views showing first to fifth steps for carrying out the method of the present invention using the apparatus of the present invention.

  First, the raw material pellets 36 charged from the raw material supply unit 38 are melted in the cylinder part 42a. At this time, the screw means 42b is moved backward so that the molten resin 36a accumulates in the vicinity of the molds 40a and 40b (first process, step 200 in FIG. 3, plasticizing stage, FIG. 4). Next, the screw means 42b is moved in the direction of the molds 40a and 40b, the resin 36a is supplied into the molds 40a and 40b, and is cooled (second process, step 202 in FIG. 3, injection cooling stage, FIG. 5). . After cooling, while removing the charge by the charge eliminator 50, one mold 40b is moved to open the molds 40a and 40b (third step, step 204 in FIG. 3, mold opening stage, FIG. 6). Finally, the container 34 is completely peeled off from the mold 40b in the static elimination state, and the molded product (container) 34 is taken out by the transport robot 54 or the like (fourth step, step 206 in FIG. 3, release stage, FIG. 7). ). Next, the molds 40a and 40b are returned to their original positions to prepare for molding the next molded product (container) 34 (fifth step, step 208 in FIG. 3, mold closing step, FIG. 8). The raw material pellets 36 are melted in the cylinder portion 42a and are always crushed by the screw means 42b so that they can be continuously injected.

  The present invention will be described more specifically with reference to the following examples. However, it is needless to say that these examples are shown by way of illustration and should not be construed in a limited manner.

(Examples 1 and 2)
In the present embodiment, the production of a storage container for storing 25 silicon wafers having a diameter of 200 mm in one box will be described. This container is a container comprising a container body and wafer storage cassette made of polypropylene resin, a lid made of polycarbonate resin, a gasket made of polyolefin elastomer, and a substrate presser made of polyester elastomer. However, some containers are provided with other parts or have different shapes, and the form of the container is not limited to this.

  The material of the container differs depending on the part to be molded, but it is formed by melting and injecting a pellet-shaped resin as a raw material. For example, the container main body and the lid were manufactured by using a pellet-shaped resin formed of polypropylene or polycarbonate resin as a raw material, and injecting it into an injection molding machine.

  The molding machine used in the molding process is a molding machine as shown in FIG. 2, and molds for components constituting the container as shown in FIGS. 9 and 10 are installed.

  In this example, static elimination was performed using an electric field line radiating static eliminator as a static eliminator at the time of molding the container main body, the lid, and the wafer storage cassette. In addition to the above, as the member forming the storage container, there are a gasket, a substrate presser, and the like as described above. However, in this embodiment, these effects are usually slight, and this time, it was manufactured without performing static elimination. Of course, it is preferable to manufacture such a member while removing electricity.

  Next, after molding, it was stored in the storage process as a temporary storage before inspection, and then in the inspection / assembly process, the appearance of molding abnormalities was inspected and the parts were assembled to complete the container. This is packaged and packaged to complete the production of the container.

  In this way, two containers (Examples 1 and 2) were prepared, and particles in those containers were confirmed. The particles were confirmed by a liquid shaking method. The liquid vibration method is a method for evaluating the cleanliness of a container such as a container. A liquid such as a definite amount of pure water is put into the container to be evaluated and vibrated to remove particles and other foreign substances adhering to the container. Are collected and analyzed. In this embodiment, as a method for evaluating a container for storing a 200 mm wafer as described above, 3 liters of ultrapure water is placed in the container, and is shaken for 2 minutes (1 minute in each of the two directions) for 20 minutes. After standing still, particles in pure water were measured with a liquid particle counter. Three times are measured and the average value is used as particle data.

  The number of particles in the two containers (Examples 1 and 2) produced in this example was as shown in Table 1.

  As is apparent from the results in Table 1, the number of particles having a size of 2 μm or more was very small, about 20. Further, the number of finer particles (0.2 μm or more) is about 2600, which is halved compared to the conventional one.

  Note that the charge amount of each member of the storage container of Example 1 was measured immediately after molding, after several hours of molding, after inspection, and after assembly. The measurement was performed with a surface electrometer. The results are shown in Table 2. It can be seen that the charge potential is suppressed to 1 kV or less by performing static elimination using the apparatus of the present invention.

(Comparative Examples 1 and 2)
Two containers were manufactured in the same manner as in Examples 1 and 2 except that the same process and apparatus as those described above were used, and the static eliminator was not used. The number of particles in the container was confirmed in the same manner as in Examples 1 and 2, and the results are also shown in Table 1. As is clear from the results in Table 1, a large number of particles were observed, with about 50 particles having a particle number of 2 μm or more and about 5000 particles (0.2 μm or more). It can be seen that the influence of adsorption of particles in the molding process is large.

  It was found that when the charge was removed as described above, the particle adhesion after manufacturing the container was reduced by about 50% compared to the case where the charge was not removed. Although this effect may vary depending on the indoor environment in which molding is performed, it is considered that the probability of particle adhesion to the molded product is reduced by at least static elimination.

  The charge amount of each member of the storage container of Comparative Example 1 was measured immediately after molding, after several hours of molding, after inspection, and after assembly. The measurement was performed with a surface electrometer. The results are shown in Table 3. It can be seen that the charging potential is high when the container is not neutralized.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and has the same function and effect can be used. Included in the technical scope.

  For example, in the above embodiment, an example in the molding process where particles are most likely to adhere is shown. However, when handling a container even in an inspection process, the container tends to be charged due to friction due to handling etc. It was in. Even in such a process, the number of particles adhering to the final product storage container can be reduced by manufacturing (inspecting) the container while removing electricity.

  Further, in this embodiment, a container for storing a wafer having a diameter of 200 mm is shown as an example. However, a large container used for a wafer having a diameter of 300 mm or the like can be similarly applied. In particular, at 300 mm, polycarbonate resin is mainly used, and the effect of static elimination is great.

  Containers manufactured in this state of static elimination have a small number of particles, which reduces the amount of particles brought into the actual process and reduces the load on the container cleaning process before the container is used. it can.

  It is preferable that the container is manufactured in a clean room, but the wafer storage box manufacturing method and manufacturing apparatus according to the present invention does not require a relatively loose clean room or clean room in the molding process or the like and has few particles. A container can be manufactured and production cost can be held down.

It is a flowchart which shows an example of the process order of the manufacturing method of the wafer storage container of this invention. It is a perspective explanatory view showing one embodiment of a wafer storage container manufacturing device of the present invention. It is a flowchart which shows an example of the procedure of the injection molding of the wafer storage container of this invention. It is a schematic diagram which shows the 1st process of the manufacturing method of the wafer storage container of this invention. It is a schematic diagram which shows the 2nd process of the manufacturing method of the wafer storage container of this invention. It is a schematic diagram which shows the 3rd process of the manufacturing method of the wafer storage container of this invention. It is a schematic diagram which shows the 4th process of the manufacturing method of the wafer storage container of this invention. It is a schematic diagram which shows the 5th process of the manufacturing method of the wafer storage container of this invention. It is a perspective view which shows the state which opened the cover body of the wafer storage container upwards. FIG. 10 is an exploded perspective view of the wafer storage container of FIG. 9. It is a flowchart which shows the process order of the manufacturing method of the conventional wafer storage container.

Explanation of symbols

  12: Wafer storage container, 14: Container body, 16: Lid, 18: Substrate storage cassette, 20: Gasket, 22: Substrate retainer, 32: Apparatus of the present invention, 34: Wafer storage container, 36: Raw material pellet, 36a: Molten resin, 38: Raw material supply section, 40: Mold, 40a: Cavity mold, 40b: Core mold, 42a: Cylinder section, 42b: Screw means, 42: Injection unit section, 43: Base body, 44: Cavity , 46: protrusion, 48: mold support, 50: static eliminator, 52: support rod, 54: transfer robot.

Claims (5)

A method of manufacturing a container for storing a semiconductor wafer, wherein the container is manufactured while removing electricity when the container is manufactured. A method of manufacturing a container for storing a semiconductor wafer, wherein the container is molded while removing electricity in a forming step of the container. The method for manufacturing a wafer storage container according to claim 1 or 2, wherein the material of the container is polypropylene resin or polycarbonate resin. An apparatus for forming a container for housing a semiconductor wafer, comprising a neutralization mechanism for neutralizing the container. A mold for molding a container for housing a semiconductor wafer, a supply unit for supplying raw material pellets as a raw material of the container, and an injection unit unit for supplying resin obtained by plasticizing and melting the raw material pellets to the mold An apparatus for manufacturing a wafer storage container, characterized in that a static eliminator is provided in the vicinity of a mold for molding the container.

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