JP5625546B2 - Wafer etching jig - Google Patents

Description

  The present invention relates to a structure of a wafer etching jig for processing a plurality of wafers in a wafer etching process.

  One of silicon wafer processing processes is an etching process. The etching process is performed for the purpose of removing processing distortion, minute defects, deposits, and the like caused by mechanical processing such as slicing and lapping, for example, with an etching solution (etchant) using a mixed acid. The front and back surfaces of the wafer are etched by submerging the wafer in an etching tank filled with an etching solution, but an etching jig called a barrel is used in the etching process to efficiently process a large number of wafers. (For example, see Patent Documents 1 to 3).

  A conventional wafer etching barrel has a large number of wafer accommodating spaces (slots) partitioned by plates, and a wafer is accommodated in each slot. A barrel containing a large number of wafers is immersed in an etching bath, and the barrel is rotated to rotate the wafer in the barrel and stir the etching solution, thereby realizing uniform etching of the main surface of the wafer. . In addition, contact prevention protrusions called “botches” are provided on both surfaces of the plate, thereby preventing the wafer and the plate from being in close contact with each other, and achieving more uniform etching.

Japanese Patent No. 3431114 JP-A-2005-050943 JP 2006-286946 A

  However, the conventional barrel for wafer etching has a problem that a convex etching abnormality occurs on the surface of the wafer because the wafer is in contact with the botch for a long time and the etching of the portion in contact with the protrusion is inhibited. . As a method for preventing an etching abnormality, a method of reducing a portion that contacts a wafer during etching, a method of stirring an etching solution by nitrogen bubbling, and the like are known. However, among these methods, the method of reducing the portion in contact with the wafer has already been implemented by Bocci, and it is impossible to reduce the contact portion further. Further, the method of performing nitrogen bubbling has a problem that not only the surface roughness of the wafer is uneven and discolored, but also nitrogen is required, which increases the cost. Therefore, a new idea for preventing an etching abnormality due to contact with the bocce is desired.

  The present invention solves the above-described problems, and an object of the present invention is to provide a wafer etching jig capable of suppressing the occurrence of an etching abnormality due to contact with a bocce.

  As a result of intensive research on the mechanism by which the surface of the wafer becomes abnormally etched by the botch, the inventors of the present application have suppressed the contact between the wafer and the protrusions when the etching solution is properly stirred together with the rotation of the barrel, and abnormal etching of the wafer. Has been found to be suppressed. The present invention is based on such technical knowledge, and a wafer etching jig according to the present invention includes a plurality of first and second side plates, a plurality of the first side plates and the second side plates. A plurality of plates defining a storage space for individual wafers between the first side plate and the second side plate, protrusions provided on both surfaces of the plate, and a central axis of the jig And at least one stirring fin provided radially outward from the shaft, and the stirring fin is a plate-like member extending in parallel with the shaft.

  According to this invention, the stirring effect of the etching liquid in a reaction tank can be heightened by the effect | action of a stirring fin. Therefore, the contact between the wafer and the protrusion in the jig can be reduced as much as possible, and the occurrence of a bunch mark on the wafer surface can be suppressed.

  In the present invention, the plurality of shafts are provided detachably with respect to the plurality of fixed shafts fixedly provided to the first and second side plates and to the first and second side plates. Preferably, the stirring fin is attached to the fixed shaft. In this case, the plurality of fixed shafts include first and second fixed shafts adjacent to the insertion rod in the circumferential direction of the first and second side plates, and a first not adjacent to the insertion rod in the circumferential direction. 3 and fourth fixed shafts, and the stirring fins include first to third stirring fins provided corresponding to three fixed shafts selected from the first to fourth fixed shafts, respectively. It is preferable. According to this configuration, an appropriate number of stirring fins can be provided at appropriate positions, and the etching solution stirring effect can be enhanced. Therefore, it is possible to reliably prevent wafer etching abnormalities.

  In the present invention, the height of the stirring fin is preferably 4% or more of the diameter of the plate. Or it is preferable that the height of the said stirring fin is 10 mm or more. According to this configuration, the stirring effect of the etching solution can be enhanced, and the wafer etching abnormality can be reliably prevented.

  According to the present invention, it is possible to suppress the occurrence of abnormal etching of a wafer due to contact with a bocce.

1 is a schematic perspective view showing a configuration of a wafer etching jig (barrel) according to a preferred embodiment of the present invention. FIG. 2 is a development view of the wafer etching barrel shown in FIG. 1, (a) is a plan view seen from the side plate 11A side, (b) is a plan view seen from the arrow X direction of FIG. 1, and (c) is a side plate 11B. It is the top view seen from the direction. 4 is a schematic plan view showing a configuration of a plate 13. FIG. 4 is a schematic cross-sectional view showing a configuration of a plate 13. FIG. It is a schematic plan view which shows the structure of the stirring fin 15a. It is a schematic sectional drawing of the stirring fin 15a along the DD line | wire of FIG.

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

  FIG. 1 is a schematic perspective view showing a configuration of a wafer etching jig (barrel) according to a preferred embodiment of the present invention. 2 is a development view of the barrel for wafer etching shown in FIG. 1, wherein (a) is a plan view seen from the side plate 11A side, (b) is a plan view seen from the arrow X direction of FIG. (C) is the top view seen from the side-plate 11B direction.

  As shown in FIGS. 1 and 2, a wafer etching barrel (hereinafter simply referred to as “barrel”) 10 according to the present embodiment includes five side plates 11A and 11B, and five side plates 11A and 11B. Shafts 12a to 12e, and a plurality of plates 13 provided between the side plate 11A and the side plate 11B. The plate 13 is for defining a wafer accommodation space, and an area sandwiched between two adjacent plates 13 and 13 is used as a wafer accommodation space. Although not particularly limited, 35 wafers can be accommodated by providing 36 plates 13 between the side plates 11A and 11B.

  The side plates 11A and 11B are both disk-shaped members and have a larger diameter than the wafer to be accommodated. A shaft member 11a is provided at the center of the outer main surface of the side plates 11A and 11B, and the shaft member 11a projects outward. The barrel 10 is rotatably supported by the shaft member 11a in the etching tank. Moreover, as shown to Fig.2 (a), the gear 11b integrated with the shaft member 11a is provided in the outer main surface of one side plate 11A. The gear 11b is connected to the gear on the drive mechanism side in the etching tank, and the barrel 10 is rotationally driven by the power of the drive mechanism.

  Although not particularly limited, the side plates 11A and 11B according to the present embodiment are composed of a side plate main body 11m and an O-ring 11o. The side plate body 11m is a disc member having a slightly smaller diameter than the side plates 11A and 11B, and the O-ring 11o is an additional member for increasing the radius of the side plate body 11m. That is, by providing the O-ring 11o on the outer periphery of the side plate body 11m, side plates 11A and 11B having a desired diameter are configured. According to this structure, the side plate of the barrel currently used conventionally can be diverted, and the side plate with a large diameter by this embodiment is realizable. Of course, it is also possible to use side plates with a large diameter from the beginning.

  The shafts 12a to 12e are members for defining a wafer accommodating space. Both ends of each shaft are connected to the outer periphery of the side plates 11A and 11B, and a space surrounded by the shafts 12a to 12e is a wafer accommodating space. The shafts 12a to 12e are preferably provided at equal intervals (about 72 °) on a circumference having a predetermined radius from the central axis.

  The shafts 12a to 12e include a single insertion rod 12a provided so as to be insertable / removable with respect to the side plates 11A and 11B, and four fixed shafts 12b to 12e provided fixed to the side plates 11A and 11B. . Among the four fixed shafts 12b to 12e, the fixed shafts 12b and 12c are adjacent to the insertion rod 12a in the circumferential direction of the side plate, and the fixed shafts 12d and 12e are not adjacent to the insertion rod 12a. The insertion rod 12a is removed when the wafer is accommodated in the barrel 10, so that the slot is opened. On the contrary, since the slot is closed when attached to the insertion rod 12a, the wafer can be enclosed in the barrel 10.

  The shafts 12a to 12e according to the present embodiment are all long shafts that pass through holes provided in the plate 13, and both ends thereof are fixed to the side plates 11A and 11B with screws. The fixed shafts 12b to 12e may be a set of short shaft pieces that are inserted between the plates 13 and 13 to connect them. In this case, the end face of the shaft piece is merely connected to the surface of the plate 13 and does not penetrate the plate 13, but it can be regarded as a single long shaft.

  FIG. 3 is a schematic plan view showing the configuration of the plate 13. FIG. 4 is a schematic cross-sectional view showing the configuration of the plate 13.

  As shown in FIGS. 3 and 4, the plate 13 is a disk-like member thinner than the side plates 11A and 11B, and has a diameter larger than the wafer W accommodated and smaller than the side plates 11A and 11B. ing. Although not particularly limited, three botches (projections) 14 a to 14 c are provided on both surfaces of the plate 13. The botches 14a to 14c are provided in order to prevent contact between the wafer W and the plate 13 during etching, and are configured as substantially conical members in particular so as to minimize the contact portions. In the absence of the botches 14a-14c, the wafer sticks to the plate 13, and both surfaces of the wafer cannot be etched uniformly. However, if the botches 14a-14c are provided, such problems should be solved. Can do. The botches 14 a to 14 c may be formed integrally with the plate 13 or may be provided as a member separate from the plate 13. The three botches 14 a to 14 c are preferably provided at equal intervals (120 °) on a circumference having a predetermined radius from the center of the plate 13.

  The barrel 10 according to the present embodiment is provided with three stirring fins 15a to 15c. The stirring fins 15a to 15c are plate-like members extending in parallel with the fixed shafts 12b to 12d. The stirring fins 15 a to 15 c serve to stir the etching solution when the barrel 10 rotates. The barrel 10 according to the present embodiment is provided immediately above the first stirring fin 15a provided immediately above the fixed shaft 12b, the second stirring fin 15b provided immediately above the fixed shaft 12b, and the fixed shaft 12c. A third stirring fin 15c is provided. The reason why the stirring fin is not provided directly above the insertion rod 12a is that the insertion port of the wafer W is blocked. Further, it is possible to provide stirring fins directly above the fixed shaft 12e, and the number of stirring fins can be four. However, since the stirring effect is not so different from the case of three, in this embodiment, the fixed shaft 12e. The stirring fin corresponding to is omitted. As described above, since the stirring fin is directly above the fixed shaft, it can be laid out without interfering with the loading / unloading of the wafer into / from the barrel. Thus, the stirring effect of the etching solution can be enhanced.

  FIG. 5 is a schematic plan view showing the configuration of the stirring fin 15a. FIG. 6 is a schematic cross-sectional view of the stirring fin 15a along the line DD in FIG. In addition, since the stirring fins 15a to 15c have the same structure, in the following description, the description of the stirring fins 15b and 15c is omitted with the stirring fin 15a as a target.

  As shown in FIGS. 5 and 6, the stirring fin 15a is fixed to the bracket 16 connected to the fixed shaft 12b with screws. The bracket 16 has a through hole 16a, and is fixed by inserting the fixed shaft 12b into the through hole 16a. The stirring fin 15 a is sandwiched between substantially U-shaped brackets 16 and fixed by screws 17.

  The stirring fins 15a to 15c according to the present embodiment may be fixed by screws to brackets coupled to the corresponding fixed shafts 12b to 12d, or may be integrated with the fixed shafts 12b to 12d. In the case where the stirring fins 15a to 15c are separate members from the corresponding fixed shafts 12b to 12d, it is possible to add the stirring fins to the conventional barrel without the stirring fins to constitute the barrel according to the present invention. The size can be easily changed. On the other hand, when the fixed shafts 12b to 12d corresponding to the stirring fins 15a to 15c are integrated, the stirring fin does not come off from the fixed shaft during etching, and therefore, a highly reliable stirring fin is provided. In addition, the manufacturing cost can be reduced by reducing the number of parts.

  The height of the stirring fins 15a to 15c is preferably 4% or more of the diameter of the side plates 11A and 11B. For example, when the diameter of the side plates 11A and 11B is about 200 to 300 mm, the height of the stirring fins 15a to 15c. Is preferably 10 mm or more. In this case, it is preferable that the upper ends of the stirring fins 15a coincide with the upper ends of the side plates 11A and 11B. If the height of the stirring fins 15a to 15c is 4% or more of the diameter of the side plates 11A and 11B, or 10 mm or more, a sufficient stirring effect can be obtained, and wafer etching abnormalities can be reliably suppressed. The height of the stirring fin means a dimension in a direction coinciding with the radial direction of the side plates 11A and 11B.

  Although the material of the barrel 10 is not particularly limited, for example, PVC (Polyvinyl Chloride) can be used. Can be formed.

  When etching a wafer using the barrel 10, the barrel 10 charged with a large number of wafers is set in an etching tank filled with an etching solution, and the front and back surfaces of the wafer are etched. As an etchant, a mixed acid in which hydrofluoric acid, nitric acid, and acetic acid are mixed at a predetermined ratio can be used. By rotating the barrel 10 in the etching tank, the wafer in the barrel 10 is rotated, whereby the wafer surface is uniformly etched and the desired flatness is maintained. The rotational speed of the barrel 10 is not limited, but is preferably 40 to 110 rpm.

  Since the barrel 10 according to the present embodiment includes the stirring fins 15a to 15c, the etching liquid is stirred by the rotation of the stirring fins 15a to 15c together with the barrel 10, and the convection of the etching liquid determines the contact time between the wafer and the bocce. It works in the direction of decreasing. Therefore, a small convex etching abnormality formed on the wafer surface by contact with the botches 14a to 14c can be suppressed.

  As described above, according to the present embodiment, the stirring effect of the etching solution in the reaction tank can be enhanced by the action of the stirring fin. Thereby, the contact between the wafer in the barrel and the bottom can be reduced as much as possible, and the occurrence of the bottom marks on the wafer surface can be suppressed.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. Needless to say, it is included in the range.

  For example, the barrel for wafer etching according to the above embodiment includes five shafts 12a to 12e and three stirring fins 15a to 15c, but the number of shafts and stirring fins is not limited thereto. The present invention can be realized even when other numbers are used.

  Moreover, in the said embodiment, although the area | region pinched | interposed between two adjacent plates 13 and 13 is used as a wafer accommodation space, this invention is not limited to such a structure, An area between the side plate 11A or an area between the plate 13 and the side plate 11B can be used as a wafer accommodating space. In this case, it is necessary to provide the botches 14a to 14c on the inner main surfaces of the side plates 11A and 11B.

  Moreover, although the case where the barrel 10 for wafer etching was used for acid etching was mentioned as an example in the said embodiment, it can also be used for alkali etching. Furthermore, it can employ | adopt for the etching process of various wafers other than a silicon wafer.

Example 1
Using a barrel (A1) according to the present invention to which a stirring fin having a height of 10 mm was attached and a conventional barrel (A2) to which no stirring fin was attached, 50,000 silicon wafers were respectively etched. The size of the silicon wafer was 150 mm, and the barrel size was 208 mm for the side plate diameter and 188 mm for the plate diameter. In the etching process, the barrel was set in an etching bath and submerged in an etching solution, and the barrel was rotated at 40 rpm to enhance the wafer etching effect. After the etching was completed, the wafer was cleaned, the surface state of the wafer was inspected, and the abnormal etching rate was determined. The abnormal etching rate is the ratio of the number of abnormal etching wafers to the total number of wafers. The results are shown in Table 1.

  As shown in Table 1, when the conventional barrel (A2) having no stirring fin is used, the abnormal etching rate of the wafer is 8%, whereas the barrel (A1) having the stirring fin is used. In this case, the rate of occurrence of abnormal etching of the wafer was 0.02%, which indicates that the rate of occurrence of abnormal etching was very low.

(Example 2)
The silicon wafer was etched while the height of the stirring fin was changed little by little. The height of the stirring fins was 0 mm (no stirring fins), 5 mm, 10 mm, 15 mm, and 20 mm, and 50 silicon wafers were etched for each. Etching conditions were the same as in Example 1. After the etching was completed, the wafer was cleaned, the surface state of the wafer was inspected, and the abnormal etching rate was determined. The results are shown in Table 2.

  As shown in Table 2, in the case of the conventional barrel (B1) without stirring fins, the number of etching abnormal occurrences was 4, but in the case of the barrel (B2) having a stirring fin of 5 mm in height, abnormal etching occurred. The number of sheets decreased to three, and in the barrel (B3) having a stirring fin having a height of 10 mm, the number of abnormal etchings was zero. Further, even in the barrels (B4, B5) having the stirring fins having a height of 15 mm and 20 m, the number of abnormal etchings was zero. From the above results, it was found that even if the fin height is about 5 mm, the effect of suppressing the etching abnormality can be obtained, but if the fin height is 10 mm or more, the etching abnormality can be reliably suppressed.

10 Wafer etching jig (barrel)
11A, 11B Side plate 11a Shaft member 11b Gear 11m Side plate body 11o O-ring 12a Shaft (Inserting rod)
12b-12e Shaft (fixed shaft)
13 Plate 14a-14c Bocchi (projection)
15a-15c Stirring fin W wafer

Claims (6)

A wafer etching jig for storing a plurality of wafers,
First and second side plates;
A plurality of shafts connecting the first side plate and the second side plate;
A plurality of plates defining an accommodation space for individual wafers between the first side plate and the second side plate;
Protrusions provided on both sides of the plate;
One or more stirring fins provided on the outer side in the radial direction than the shaft as seen from the central axis of the jig,
The plurality of shafts includes a plurality of fixed shafts fixed to the first and second side plates, and at least one provided detachably to the first and second side plates. Including a book stick,
The stirring fin is a plate-like member extending in parallel with the shaft, and is attached to the fixed shaft . The plurality of fixed shafts include first and second fixed shafts that are adjacent to the insertion rod in the circumferential direction of the first and second side plates, and third and fourth that are not adjacent to the insertion rod in the circumferential direction. Including a fixed shaft of
The stirring fins, according to claim 1, characterized in that it comprises first to third agitation fin provided corresponding to the first to three fixed shaft selected from the fourth stationary shaft Wafer etching jig. The jig for wafer etching according to claim 1 or 2 , wherein a height of the stirring fin is 4% or more of a diameter of the plate. The wafer etching jig according to claim 1, wherein a height of the stirring fin is 10 mm or more. The wafer etching jig according to claim 1 , wherein the stirring fin is a separate member from the shaft. 5. The wafer etching jig according to claim 1 , wherein the stirring fin is integrated with a corresponding shaft.

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