JP2006297686A - Support plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a support plate used for supporting a sheetlike article when the sheetlike article like a silicon wafer is ground or diced and capable of easily cutting off a gate mark projection by a cutter or a nipper without damaging a product. <P>SOLUTION: The gate mark projections 1 are vertically provided to the outer edge part of the upper surface of the support plate 21 at opposed positions. When the gate mark projections 1 are cut off by the nipper or the like, they become slightly thicker than the product to become an obstruction in a case that the silicon wafer is ground. Accordingly, the gate mark projection 1 are made less than the wall thickness of the product using a drilling machine. By setting the positions of the gate mark projections 1 to the outer edge part of the support plate, the gate mark projections 1 can be easily cut off by the cutter or the nipper without damaging the product. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a support plate made of a thermoplastic resin used for supporting a plate-like object such as a silicon wafer when it is polished or diced.

  A semiconductor integrated circuit (hereinafter referred to as an IC chip) is usually formed by slicing a high-purity silicon single crystal or the like into a silicon wafer, forming a predetermined circuit pattern on the wafer surface using a photoresist, and then backside the wafer. Is polished by a polishing machine to reduce the thickness of the wafer, and finally the wafer is diced into chips.

  In recent years, the use of IC chips has been expanded, and an extremely thin silicon wafer (hereinafter referred to as an ultrathin wafer) having a thickness of about 50 μm has been required. However, the ultra-thin wafer is inferior in handling because it has a large warp and is easily cracked by impact compared to a conventional one having a thickness of about 100 to 600 μm, and it may be damaged if it is processed in the same way as a conventional silicon wafer is there.

  In addition, an ultra-thin wafer is easily damaged by an impact and has a high risk of breakage in a polishing process or a dicing process, and is easily broken when a bump (fine electrode) is formed on an IC chip, so that the yield is poor. For this reason, it is required to improve the handleability of the wafer in the process of manufacturing the IC chip from the ultra-thin wafer.

  In response to this requirement, a method has been proposed in which a wafer is affixed to a support plate using a support tape, and the wafer is polished while being fixed to the support plate. According to this method, the handleability of the wafer is improved, and ultrathin wafers and IC chips can be manufactured with a high yield.

  Various tapes have been developed as support tapes (see Patent Document 1). In particular, there is a commercially available product that controls the adhesive strength of the tape by applying light stimulation to the support tape (manufactured by Sekisui Chemical Co., Ltd.). "Selfa BG"). In such a method for controlling the adhesive force by light, it is considered that there is less damage to the wafer and no adverse effect on peripheral devices than the method of controlling the adhesive force by applying heat stimulation. A glass plate is widely used as the support plate. This is because glass can transmit visible light and ultraviolet light and can control the adhesive force of the support tape, and the handleability is not good, but it has a low coefficient of linear expansion and is suitable for polishing.

In recent years, plastic support plates have been developed. However, this has drawbacks such as low rigidity, a large linear expansion coefficient, and a narrow range of application to silicon wafers. These plastic support plates are formed using, for example, the apparatus described in Patent Document 2.
JP 2003-171624 A JP-A-55-146714

  In the manufacturing method of the support plate using the apparatus described in Patent Document 2, the molten resin is injected into the center of the cavity for forming the support plate, and the molten resin is caused to flow so as to spread concentrically outward from the radial direction. In this apparatus, an inflow port of a molten resin called a gate opens at the center of the cavity, and a projection remains at a position corresponding to the gate in a molded product, that is, a support plate, which is taken out from the mold.

  Throughout the claims and the entire specification, the protrusions remaining on the molded product after molding are referred to as “gate trace protrusions”, and the portions where the protrusions existed on the surface of the molded product after the protrusions have been cut off. A surface formed by further cutting or grinding the gate mark protrusion or the gate mark is called a “gate portion removal surface”. Further, the size and shape of the gate and the gate mark protrusion formed thereby are not limited, and for example, a cone, a pyramid, a truncated cone, a truncated pyramid, a cylinder, a prism, a semicircular section, etc. It may be. Further, the gate trace protrusions include those in which the above-mentioned shape is excised leaving the base.

In order to use the molded product as a support plate for polishing a wafer, it is necessary to cut off the gate trace protrusion. However, since the protrusion is located at the center of the plate as described above, a cutting tool such as a cutter or a nipper may come into contact with a portion other than the center, for example, a peripheral portion, to damage the product. . In addition, because the protrusion is located in the center, if the excision trace protrudes from the plate surface, there is a problem that the plate rattles when placed with this surface down, and the excision trace is recessed from the plate surface. In this case, although the rattling can be prevented, there is a problem that the wafer is recessed due to the pressing force during polishing, and uniform processing cannot be performed.

  This invention makes it a subject to provide the support plate which can solve the said problem of a prior art.

  The invention according to claim 1 is a support plate made of an injection molding method and made of a thermoplastic resin for supporting a silicon wafer to be polished or diced, wherein the gate trace protrusion or the gate trace is one of the two. It is a support plate located in the outer edge part of a plate surface (refer FIG. 1).

  In the support plate according to the present invention, the gate trace is formed on the outer edge portion of one plate surface by opening the gate at the outer edge portion of the cavity for forming the support plate. Thus, by setting the position of the gate mark protrusion to the outer edge portion of the support plate, the gate mark protrusion can be easily removed with a cutter or a nipper without damaging the product.

  The invention according to claim 2 is a support plate made of a thermoplastic resin made by an injection molding method for supporting a silicon wafer to be polished or diced, wherein the gate trace protrusion or the gate trace is formed on the plate. The support plate is located on a peripheral side surface.

  The gate trace protrusion may be formed directly on the peripheral side surface of the plate (see FIG. 9), or may be formed on an outward projection provided on the outer peripheral surface of the support plate (see FIG. 2).

  In the support plate according to the present invention, gate traces are formed on the peripheral side surface of the plate by opening the gate on the peripheral side surface of the cavity for forming the support plate. Thus, by making the position of the gate trace protrusion on the peripheral side surface of the support plate, the gate trace protrusion can be removed more easily, and the product is not damaged with the excision.

  Although the direction of the gate mark protrusion is not limited, it is preferably an outward protrusion.

  A third aspect of the present invention is the support plate according to the first or second aspect, wherein a plurality of gate trace protrusions or gate traces, preferably 2 to 4, are provided.

  The relative positions of the plurality of gate traces or gate traces are not limited, but they are preferably positioned to face each other across the center of the support plate.

  When molding a support plate having a diameter of 100 to 150 mm, one gate may be used. However, when molding a support plate having a larger diameter, by providing a plurality of gates, the molten resin is poured into the cavity through the gates. The resistance can be lowered, the molten resin can be filled into the cavity at a low pressure, the pressure loss can be reduced, and thereby the dimensional accuracy of the product can be increased, and a homogeneous and highly accurate product can be molded.

  According to a fourth aspect of the present invention, in the support plate according to the first or second aspect, the gate portion removal surface is flush with the plate surface or the plate peripheral side surface, or is recessed from the plate surface or the plate peripheral side surface. It is a support plate characterized by being.

 When the gate mark protrusion or gate mark is further cut or ground to form the gate removal surface, the gate mark protrusion or gate mark can be cut with a cutting tool such as a cutter or nipper, using a laser or the like. Can also be done.

  The depth of the recessed gate portion removal surface is not limited, but is preferably 50 μm or less.

  Grinding of the recessed gate portion removal surface can be performed, for example, by attaching a blade such as an end mill or a drill to a machine tool such as a drilling machine and rotating these blades. The surface having the recessed gate portion removal surface formed in this way is used as the back surface, a wafer is attached to the surface, and the wafer is polished or diced.

  The invention according to claim 5 is the support plate according to claim 1, wherein the gate mark is removed by a through hole penetrating the plate.

  The shape of the through hole may be a circular cross section, a rectangular cross section, or the like. The through holes can be formed by, for example, attaching a blade such as an end mill or a drill to a machine tool such as a drilling machine and rotating these blades. This method is easier than the method using a tool such as a cutter or a nipper, and there is very little risk of causing unnecessary scratches on other portions of the plate. When using a support plate having a through-hole formed in this way, if a wafer having a smaller diameter than this is attached to the plate, the wafer can be polished or diced without any influence of the through-hole (see FIG. 8).

  The invention according to claim 6 is the support plate according to claim 2, wherein the dimension of the gate trace protrusion in the plate thickness direction is smaller than the plate thickness.

  As shown in FIG. 9, the dimension of the gate trace protrusion in the plate thickness direction may be less than the plate thickness. However, in consideration of the fluidity of the molten resin, it is preferably at least 1/2 of the plate thickness and the plate thickness. Is less than.

  Since the entire plate surface can be used, the support plate according to the present invention can be suitably used for attaching a wafer having substantially the same diameter to the support plate (see FIG. 10) and polishing or dicing the wafer.

  When the dimension of the gate trace protrusion in the plate thickness direction exceeds the plate thickness, the wafer trace protrusion and the wafer interfere with each other when the wafer having the same diameter is placed on the support plate, and the wafer cannot be placed.

  The invention according to claim 7 is the support plate according to claim 2, wherein the gate portion removal surface is concentrically curved with the peripheral side surface of the plate.

 The gate part removal surface formed by cutting or grinding the gate trace protrusion or the gate trace may be flush with the peripheral side surface of the plate, may be raised from the peripheral side surface of the plate, or may be recessed. However, in the former two cases, it is preferable that the removal surface be curved concentrically with the peripheral side surface of the plate. 4 shows an example in which the gate portion removal surface is raised from the peripheral side surface of the plate, and FIGS. 5 and 6 show examples in which the gate portion removal surface is recessed from the peripheral side surface of the plate. When the gate portion removal surface is recessed from the peripheral side surface of the plate, the depth is preferably about 5 μm to 1 mm.

  In order to curve the gate portion removal surface concentrically with the peripheral side surface of the plate, for example, the gate portion removal surface is ground to a desired surface using a cutter, a nipper, an end mill, a grinder, or the like.

  When the gate part removal part formed by removing the gate trace protrusion protrudes from the peripheral side surface of the plate and is not curved concentrically with the peripheral side surface of the plate, it is conveyed while pinching the peripheral side surface of the support plate In the wafer polishing apparatus that performs the above, there is a possibility that the protruding gate portion removing portion hits the wafer polishing apparatus when the support plate is transported and the support plate and the wafer fall. In the present invention, since the gate portion removal surface is concentrically curved with the peripheral side surface of the plate, such a problem can be avoided.

  According to the first aspect of the present invention, since the gate trace protrusion is located at the outer edge portion, the gate trace protrusion can be easily excised with a cutter, a nipper or the like without damaging the product.

  According to the second aspect of the present invention, since the gate trace protrusion is located on the peripheral surface of the plate, the gate trace protrusion can be more easily removed, and the product is not damaged with the excision. According to the invention of claim 3, by providing a plurality of gates so as to form a plurality of gate trace protrusions, it is possible to reduce the resistance when the molten resin is poured into the cavity through the gates. The cavity can be filled at a low pressure, reducing the pressure loss, thereby increasing the dimensional accuracy of the product and forming a homogeneous and high-precision product.

  According to the fourth aspect of the present invention, the gate portion removal surface is flush with the plate surface or the plate circumferential side surface, or is recessed from the plate surface or the plate circumferential side surface. No rattling occurs when the plate is placed.

  According to the fifth aspect of the present invention, since the gate mark is removed by the through hole penetrating the plate, if a wafer having a smaller diameter is attached to the support plate, the influence of the through hole is not affected at all. Polishing or dicing can be performed (see FIG. 8).

  According to the invention of claim 6, since the dimension of the gate trace protrusion in the plate thickness direction is smaller than the plate thickness, the entire plate surface can be used, and a wafer having substantially the same diameter as this is attached to the support plate. Dicing can be performed.

  According to the seventh aspect of the present invention, since the gate portion removal surface is concentrically curved with the peripheral side surface of the plate, the protruding gate portion removal portion hits the wafer polishing apparatus when the support plate is conveyed by the conveyor. The problem of falling wafers does not occur.

  Next, in order to describe the present invention specifically, examples of the present invention will be given.

  First, an example of a mold for producing a molded product by an injection molding method is shown.

Mold example 1
FIG. 13 shows a conventional mold. In FIG. 13, (10) is a sprue that receives the molten resin injected from the nozzle of the injection molding machine, (8) is a runner that is a passage for the molten resin, and (9) is from the sprue (10) through the runner (8). It is a gate which is an inflow port for introducing the molten resin coming into the cavity (11) of the mold (12). (13) is a heater.

  In this mold (12), since the gate (9) is opened in the center of the cavity (11), the molded product taken out from the cavity (11) after the molding is completed, that is, the support plate (21) is shown in FIG. As shown, the gate trace protrusion (1) remains in the center of the upper surface. Since the gate trace protrusion (1) is located at the center of the support plate (21) in this way, it is necessary to move a cutter or nipper or other cutting device or tool for cutting this to the center of the support plate (21). In this case, the cutting device or tool may come into contact with the surface of the support plate (21).

  When injection molding was performed using this mold (12), the cavity (11) had a diameter of 200 mm and the molten resin pressure of the molten resin injected from the nozzle of the injection molding machine was 44 MPa. The variation in thickness of the support plate (21) was ± 9.5 μm.

Mold example 2
FIG. 11 shows an example of an improved mold. In FIG. 11, the cavity (11) has outward projections (11a) at two opposing positions on the outer peripheral surface, and a gate (9) is opened in these outward projections (11a). With this structure, the molten resin flows into the cavity (11) from the outer periphery through the gate (9).

  In this mold (12), the gate (9) is opened to a pair of outward projections (11a) provided on the outer peripheral surface of the cavity (11), so that it is removed from the cavity (11) after completion of molding. As shown in FIG. 2, gate trace protrusions (1) remain on the molded product, that is, the pair of outward protrusions (21a) of the support plate (21).

Mold example 3
In FIG. 11, the cavity (11) has outer protrusions (11a) at four positions at equal intervals on the outer peripheral surface, and a gate (9) is opened in these outer protrusions (11a). Other configurations are the same as those of the mold example 2.

  In this mold (12), since the gate (9) is open to four outward projections (11a) provided on the outer peripheral surface of the cavity (11), the gate (9) is taken out from the cavity (11) after completion of molding. Gate trace protrusions (1) remain on the four outer protrusions (21a) of the molded product, that is, the support plate (21).

There remain four outward projections (21a).

  When injection molding was performed using this mold (12), the cavity (11) had a diameter of 200 mm and the molten resin pressure of the molten resin injected from the nozzle of the injection molding machine was 31 MPa. The variation in thickness of the support plate (21) was ± 7.5 μm. Therefore, compared with the case where the mold example 1 is used, an effect of reducing the pressure of the molten resin and an effect of improving the dimensional accuracy of the product are recognized.

Production example 1 of support plate
In FIG. 1, a gate trace protrusion (1) is provided vertically at a position facing the outer edge of the upper surface of the support plate (21).

  When cutting the gate trace protrusion (1), the gate trace protrusion will become slightly thicker than the product if it is cut with a nipper, etc., which will be an obstacle when polishing the wafer. Make it thinner than the wall thickness.

Production example 2 of support plate
In FIG. 2, a pair of outward projections (21a) are provided at positions opposed to the outer peripheral surface of the support plate (21), and gate trace projections (1) are formed on one surface of these outward projections (21a), respectively. Is formed. The gate trace protrusion (1) is provided perpendicular to one surface of the outward protrusion (21a).

Production example 3 of support plate
In FIG. 3, a pair of outward projections (21a) are provided at opposing positions on the outer peripheral surface of the support plate (21), and these outward projections (21a) are thinned from the base end portion to the distal end portion. The upper surface is inclined so as to be Gate trace protrusions (1) are formed on the inclined upper surface in this way. The gate trace protrusion (1) is provided perpendicular to one surface of the outward protrusion (21a).

Production example 4 of support plate
In the example of FIG. 4, the gate trace protrusion remaining on the peripheral side surface of the support plate (21) is removed leaving the base, thereby forming a gate portion removal portion (3) that rises from the peripheral side surface of the plate, The outer peripheral surface, that is, the gate portion removal surface (3a) is curved concentrically with the peripheral side surface of the support plate (21).

Production example 5 of support plate
In the example of FIG. 5, the gate trace protrusion remaining on the peripheral side surface of the support plate (21) is removed, thereby forming a circular gate portion removal portion (4) recessed from the peripheral side surface of the plate. The gate portion removal surface (4a) is concentrically curved with the peripheral side surface of the support plate (21). The depth of the circular gate portion removal portion (4) is about 0.1 mm.

Production example 6 of support plate
In the example of FIG. 6, the gate trace protrusion remaining on the peripheral side surface of the support plate (21) is removed to form a rectangular gate portion removal portion (5) recessed from the peripheral side surface of the plate. The gate portion removal surface (5a) is concentrically curved with the peripheral side surface of the support plate (21). The depth of the rectangular gate portion removing portion (5) is about 0.1 mm.

Production example 7 of support plate
In FIG. 7, by removing the gate trace protrusion remaining on the outer edge of one plate surface of the support plate (21), a circular gate portion removal portion (6) is formed. (6a) is recessed from the peripheral side of the plate. The depth of the circular gate portion removal portion (6) is about 0.1 mm.

Production example 8 of support plate
In FIG. 8, the gate trace protrusion remaining on the peripheral side surface of the support plate (21) is removed to form a gate portion removal surface, and a circular through hole (7) penetrating the plate (21) on the removal surface. Is provided. A wafer (31) having a smaller diameter is attached to the support plate (21), and the wafer is polished or diced.

Production example 9 of support plate
In FIG. 9, the dimension of the gate trace protrusion (18) remaining on the peripheral side surface of the support plate (21) in the plate thickness direction is about 2/3 of the plate thickness.

Preparation Example 10 of Support Plate
In FIG. 10, a wafer (31) having substantially the same diameter as that of the support plate (21) of Production Example 9 of the support plate is pasted.

It is a perspective view which shows the support plate by this invention. It is a perspective view which shows the support plate by this invention. It is a perspective view which shows a part of support plate by this invention. It is a perspective view which shows a part of support plate by this invention. It is a perspective view which shows a part of support plate by this invention. It is a perspective view which shows a part of support plate by this invention. It is a perspective view which shows the support plate by this invention. It is a perspective view which shows the support plate by this invention. It is a perspective view which shows a part of support plate by this invention. It is a perspective view which shows the support plate by this invention. It is a longitudinal cross-sectional view which shows the metal mold | die for manufacturing the support plate by this invention. It is a perspective view which shows the conventional support plate. It is a longitudinal cross-sectional view which shows the metal mold | die for manufacturing the conventional support plate.

Explanation of symbols

(1) (18): Gate trace protrusion
(21): Support plate
(21a): Outward protrusion
(3) (4) (5) (6): Gate part removal part
(3a) (4a) (5a) (6a): Gate part removal surface
(7): Through hole
(31): Wafer

Claims (7)

  A support plate made of a thermoplastic resin made by an injection molding method for supporting a silicon wafer to be polished or diced, wherein the gate trace protrusion or gate trace is located at the outer edge of one plate surface Support plate characterized by.   A support plate made of a thermoplastic resin made by an injection molding method for supporting a silicon wafer to be polished or diced, characterized in that the gate trace protrusion or gate trace is located on the peripheral side surface of the plate Support plate.   3. The support plate according to claim 1, wherein a plurality of gate trace protrusions or gate traces are provided.   3. The support plate according to claim 1, wherein the gate portion removal surface is flush with the plate surface or the plate peripheral side surface or is recessed from the plate surface or the plate peripheral side surface.   2. The support plate according to claim 1, wherein a gate mark is removed by a through hole penetrating the plate.   3. The support plate according to claim 2, wherein the dimension of the gate trace protrusion in the plate thickness direction is smaller than the plate thickness. 3. The support plate according to claim 2, wherein the gate portion removal surface is curved concentrically with the peripheral side surface of the plate.

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