JP2005109433A - Method for abrading semiconductor wafer and protecting member of bump for abrading - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To protect a semiconductor wafer from breaking in the course of abrading the rear surface of the semiconductor wafer by putting an abrasive wheel against the semiconductor wafer so as not to concentrate stress in bumps, and to protect a part of an adhesive from remaining on the bumps during peering a protective tape. <P>SOLUTION: A method for abrading a semiconductor wafer comprises: a protection member disposing step for protecting bumps 19 using a protection member 10 including a periphery adhesive part 11 to be adhered to the periphery of a semiconductor wafer 14 on which the bumps 19 are not formed, a bump protection part 12 surrounded by the periphery adhesive part 11 to support and protect the bumps 19, and a concave 13 formed of the periphery adhesive part 11 and the bump protection part 12 to contain the bumps 19; and an abrading step for holding the protection member side of the semiconductor wafer 14 on a chuck table 2 and for abrading the rear surface of the semiconductor wafer 14 with an abrading means. An external peripheral area of the semiconductor wafer is supported completely by the periphery adhesive part 11 of the protection member 10. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a semiconductor wafer grinding method for thinly and evenly grinding the entire back surface of a semiconductor wafer on which a plurality of semiconductor chips, such as IC and LSI, are formed, by a grinding device, and the protection used for the grinding. This relates to the member.

  A semiconductor wafer in which a plurality of semiconductor chips such as ICs and LSIs of this type are formed is ground to the required thickness by grinding the back surface with a grinding machine, and then divided into individual semiconductor chips with a dividing device such as a dicing machine. It is widely used by being incorporated in circuits of electric devices such as mobile phones and personal computers.

  By the way, on the surface of a semiconductor chip such as IC or LSI, metal protrusions of about 50 to 170 μm called bumps are formed so that they can be directly mounted on the electrodes of the wiring board via the bumps. This makes it possible to reduce the size and weight of electrical equipment.

  However, in order to grind the back surface of the semiconductor wafer, a protective tape or the like is attached to the front surface side of the semiconductor wafer, and the protective tape side is placed in contact with the chuck table of the grinding device. In this case, the grinding is performed by pressing a grinding wheel to cause a problem that stress is concentrated on the bumps and the semiconductor wafer is damaged.

In addition, an energy ray curable adhesive tape comprising a base film and an energy ray curable adhesive layer is attached to the surface of a semiconductor wafer having a step of about 10 to 60 μm in the formed circuit pattern, and energy irradiation is performed. It is well known that grinding is performed after the adhesive layer has been cured, and the unevenness on the wafer surface is buffered by the adhesive layer, and damage can be prevented even if the wafer is ground thinly. The IC chip can be manufactured with high yield.
Japanese Patent No. 3330851

  Therefore, it is conceivable to apply this known technique to backside grinding of semiconductor wafers with bumps formed. In that case, a thick adhesive layer of an energy ray curable adhesive tape, which is a so-called protective tape, is formed. Then, it is recognized that the periphery of the bump is hardened by wrapping it with an adhesive layer, and then the grinding is performed.

  However, if an energy ray curable adhesive tape with a thick adhesive layer is used, the adhesive layer around each bump may be cured even if the adhesive layer is cured and easily peeled off from the surface of the semiconductor wafer. Part of the layer often remains, and when mounting the semiconductor chip on the wiring board, the bump layer is insulated or disconnected by the remaining adhesive layer, and proper mounting is not performed Have

  In addition, the energy ray curable pressure-sensitive adhesive tape having a known pressure-sensitive adhesive layer requires that the pressure-sensitive adhesive layer be formed thick over the entire surface corresponding to the size of the wafer, and that much pressure-sensitive adhesive is required. As a result, not only is the material wasted, but also the irradiation of energy rays must be carried out evenly over a wide range, and since the entire surface is adhered, care must also be taken for the peeling operation. There is a problem that workability is poor.

In the backside grinding method for semiconductor wafers with multiple bumps formed on the surface, the problem to be solved is to prevent damage to the semiconductor wafer by preventing stress from concentrating on the bumps when grinding by pressing a grinding wheel. It is to grind so that a part of the adhesive does not remain on the bump when the protective tape is peeled off.
In addition to the above-described problems, the protective tape is to reduce the amount of adhesive used to eliminate material waste and to improve the workability of energy irradiation work and protective tape peeling work.

  1st invention which concerns on this invention is a method of grinding the back surface of the semiconductor wafer in which the several bump was formed in the surface, Comprising: The outer periphery sticking part stuck on the outer peripheral area | region of the semiconductor wafer in which bump is not formed And a bump protecting part surrounded and supported by the outer periphery attaching part for supporting and protecting the bump, and a recess formed by the outer periphery attaching part and the bump protecting part for accommodating the bump. , And a protective member disposing step for protecting the bumps with the bump protecting portion by attaching the outer peripheral attaching portion of the protective member to the outer peripheral region of the surface of the semiconductor wafer, and holding the protective member side of the semiconductor wafer on the chuck table The semiconductor wafer grinding method is characterized in that it comprises a grinding step of grinding the back surface of the semiconductor wafer with a grinding means.

  A second invention according to the present invention is a protective member that protects the back surface of a semiconductor wafer having bumps formed on the front surface, and an outer periphery bonding portion that is bonded to the outer peripheral region of the semiconductor wafer on which bumps are not formed. A bump protection part that is surrounded by the outer peripheral sticking part and supports and protects the bump, and a concave part that is formed by the outer peripheral sticking part and the bump protective part and accommodates the bump. The bump protection member for grinding.

In the semiconductor wafer grinding method according to the present invention, the outer peripheral adhesive part of the protective member is attached to the outer peripheral region of the semiconductor wafer, and the bumps are protected by the inner bump protective part surrounded by the outer peripheral adhesive part. In particular, since the outer peripheral area of the semiconductor wafer is entirely supported by the outer peripheral sticking part of the protective member, the grinding wheel is pressed evenly against the back surface of the semiconductor wafer, Since the grinding is performed and no stress is concentrated on the bumps, the semiconductor wafer can be prevented from being damaged.
In addition, since the protective member attached to the semiconductor wafer is attached only at the outer peripheral attaching portion in the outer peripheral region of the semiconductor wafer, the adhesive does not come into contact with the bump. No part of the adhesive remains on the surface.

  In addition, the bump protection member according to the present invention includes an outer peripheral sticking portion that is attached only to the outer peripheral region of the semiconductor wafer, and a bump protective portion that is surrounded by the outer peripheral sticking portion and is protected by abutting the tip portion of the bump. Since the outer periphery sticking part has a ring shape, the amount of adhesive used can be significantly reduced, and UV irradiation can be performed simply along the ring shape. Moreover, since the outer peripheral sticking portion is an outer peripheral region where no bump is formed, the protective member can be easily peeled off.

  In the method of grinding the backside of a semiconductor wafer with multiple bumps formed on the surface, when grinding with a grinding wheel pressed against the backside of the semiconductor wafer, the outer peripheral area of the semiconductor wafer sinks and stress concentrates on the bumps In order to prevent the wafer from being damaged, at least the outer peripheral adhesive part that is attached to the outer peripheral region of the semiconductor wafer on which no bumps are formed and the inner side surrounded by the outer peripheral adhesive part support and protect the bumps. Using a protection member composed of a bump protection part that performs grinding, the entire back surface of the semiconductor wafer is supported and ground so as to be substantially horizontal, and the outer peripheral sticking part of the protection member is a bump. Since the adhesive does not come into contact with the bumps, even if the protective member is peeled off after the grinding process, no adhesive is applied to the areas where the bumps are formed. That the residual to prevent the occurrence, is obtained by implementation.

  A grinding method of a semiconductor wafer according to the present invention will be described with reference to the drawings. FIG. 1 shows an example of a grinding apparatus 1 used in the grinding method of the present invention. The chuck table 2, the grinding wheel 3, the drive unit 4 that drives the grinding wheel 3, the guide unit 5 that supports the drive unit 4 and guides movement in the vertical direction, and the drive unit via the guide unit 5 And a moving drive unit 6 for precisely moving 4 in the vertical direction.

  FIG. 2 shows a protective member 10 according to the present invention. The protective member 10 is used by being attached to a semiconductor wafer to be ground, and is composed of a ring-shaped outer peripheral adhesive portion 11 and a flat bump-protecting portion 12.

  The ring-shaped outer peripheral sticking portion 11 constituting the protective member 10 is formed by, for example, coating the surface of a ring-shaped polyolefin or the like with an acrylic resin containing a component that is cured by UV irradiation, and the outer diameter thereof is to be stuck. The thickness of the semiconductor wafer is approximately equal to the outer diameter of the semiconductor wafer, and the thickness thereof is approximately equal to the height of the bump formed on the semiconductor wafer. Further, the flat bump protection portion 12 is, for example, a sheet-like or tape-like shape formed of polyolefin having a thickness of 100 to 200 μm, and is formed in substantially the same shape as the semiconductor wafer. By attaching (attaching) the outer periphery attaching part 11 integrally, the inner side of the outer periphery attaching part 11 becomes the recessed part 13 which accommodates a bump.

  FIG. 3 shows an example of a semiconductor wafer to which the protective member 10 is stuck and ground. The semiconductor wafer 14 is formed with a plurality of semiconductor chips 16 partitioned by streets 15 on the surface side, and an outer peripheral region 17 where the semiconductor chip 16 is not formed exists in the outer peripheral portion. In addition, the outer peripheral sticking portion 11 of the protective member 10 is stuck, and the plurality of semiconductor chips 16 are surrounded by the concave portions 13. A notch 18 indicating a crystal orientation is formed at the outer peripheral edge of the semiconductor wafer 14.

  As shown in FIG. 4, a plurality of bumps 19 having a required height are formed on each semiconductor chip 16, and the bumps 19 can be mounted on the electrodes of the wiring board. The height of the bump 19 in this case is in a range of about 50 to 170 μm, and the height is selected depending on the type of the semiconductor chip 16 or the place of use, and is formed on each semiconductor chip 16 in the single semiconductor wafer 14. All the bumps 19 are formed at the same height.

  After attaching or arranging the protective member 10 to the semiconductor wafer 14, as shown in FIG. 5, the chuck table of the grinding apparatus 1 with the back side of the semiconductor wafer 14 facing up and the protective member 10 facing down. 2 is mounted and fixed by suction to perform the grinding process.

  FIG. 6 is a partially enlarged view showing a state where the protective member 10 is attached to or disposed on the semiconductor wafer 14. As is clear from the figure, when the protective member 10 is adhered and disposed on the semiconductor wafer 14, the outer peripheral adhesive portion 11 is adhered to the outer peripheral region 17, and all the bumps 19 are located in the recess 13. The tip end portion comes into contact with the bump protection portion 12 almost evenly.

  In this case, the thickness of the outer peripheral sticking portion 11 in the protective member 10 substantially corresponds to the height of the bump 19 formed on the semiconductor wafer 14. If the height of the bump 19 is 50 μm, the outer periphery If the thickness of the sticking part 11 is also formed in the range of 50 ± 5 μm and the height of the bump 19 is 170 μm, the thickness of the outer peripheral sticking part 11 is also formed in the range of 170 ± 5 μm. Accordingly, the thickness of the outer peripheral sticking portion 11 is appropriately determined according to the height of the bump 19 formed on the semiconductor wafer 14 on which is disposed.

  In short, the protective member 10 is formed as a separate member in a completely separate process from the semiconductor wafer 14, and the surface side of the semiconductor wafer 14 is removed at the stage of the grinding process in which the back surface of the semiconductor wafer 14 is ground and thinned. In addition, depending on the type / function of the semiconductor wafer, the usage, etc., the size of the wafer, the size of the chip, the height of the bump, etc. are different. Correspondingly, the protective member 10 is selected, and in particular, the thickness of the outer peripheral sticking portion 11 of the protective member 10 is appropriately set with respect to the height of the bump.

  Then, the bump 19 is protected by the bump protector 12 at the stage where the protective member 10 is attached or disposed on the outer peripheral region 17 where the bump is not formed on the semiconductor wafer 14. At the same time, since the outer peripheral region 17 including the outer peripheral surface of the semiconductor wafer 14 is supported by the outer peripheral bonding portion 11 having a thickness corresponding to the height of the bump 19, the rear surface side of the semiconductor wafer 14 is entirely horizontal. Will be supported.

  As shown in FIG. 1, the semiconductor wafer 14 to which the protective member 10 is properly attached or disposed is placed with the protective member 10 abutting against the chuck table 2, and the grinding wheel 3 is placed on the semiconductor wafer. Although pressed against the back side of the wafer 14 and ground, the bump 19 is protected by the bump protector 12 and the outer peripheral area 17 is supported by the outer peripheral adhesive part 11, so that the stress is applied to the outer peripheral adhesive part 11 and the bump. As a result, the semiconductor wafer 14 is absorbed by the protection portion 12 and is not concentrated on the bump 19, so that the semiconductor wafer 14 is not damaged in the cutting process.

  Further, in this grinding process, even if the back surface side of the semiconductor wafer 14 is ground while supplying the grinding water with the grinding stone 3, there is no gap between the outer peripheral attachment portion 11 attached to the outer peripheral region 17. Therefore, the dirty grinding water does not penetrate into the recess 13 from the outer peripheral edge of the semiconductor wafer 14, and therefore there is no possibility of contaminating the semiconductor chip 16.

  After this grinding process is completed, the semiconductor wafer 14 is picked up from the grinding apparatus 1 and, for example, is properly oriented based on the notch 18 indicating the crystal orientation, and is placed and stuck on the dicing tape of the dicing frame, Even when the protective member 10 is peeled off, only the outer peripheral sticking portion 11 of the protective member 10 is stuck to the outer peripheral region 17 of the semiconductor wafer 14, so that the peeling work is easy and the bump 19 portion Thus, no adhesive remains, and various operations related to grinding can be smoothly performed. In addition, when the outer periphery sticking part 11 has the property hardened | cured by UV irradiation, it is preferable to irradiate UV before peeling and to reduce adhesive force.

  The method for grinding a semiconductor wafer according to the present invention is a method for grinding a back surface of a semiconductor wafer having a plurality of bumps formed on the surface thereof. At least an outer periphery attaching portion for attaching to an outer peripheral region of a semiconductor wafer on which no bumps are formed. And a bump protection part that supports and protects the bumps on the inner side surrounded by the outer periphery sticking part, and supports and grinds the entire back surface of the semiconductor wafer substantially horizontally. By doing so, it is possible to prevent the outer peripheral region of the semiconductor wafer from sinking and stress from concentrating on the bumps when the grinding wheel is pressed against the back side of the semiconductor wafer for grinding. Furthermore, since the outer peripheral sticking part of the protective member is formed in a ring shape and does not reach the area where the bump is formed, the adhesive does not contact the bump. Since it is configured as described above, even if the protective member is peeled off after the grinding process, it is possible to prevent any adhesive from remaining in the region where the bumps are formed. In this type of semiconductor wafer, It can be widely used in the manufacture of semiconductor chips that are made smaller and thinner by grinding the back surface efficiently.

It is the perspective view which showed the grinding device used for the grinding method of the semiconductor wafer which concerns on the specific Example of this invention. It is the perspective view which showed the protection member used for grinding of the Example. It is the perspective view which showed the condition which arrange | positions the protection member in the surface side of the semiconductor wafer to be ground. It is the perspective view which expanded the semiconductor chip and bump formed in the surface side of the semiconductor wafer to be ground, and showed a part enlarged. In the Example, it is the perspective view which showed the back surface side of the semiconductor wafer which arrange | positioned the protection member. It is an expanded sectional view which follows the AA line of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Grinding device 2 Chuck table 3 Grinding wheel 4 Drive part 5 Guide part 6 Movement drive part 10 Protective member 11 Peripheral adhesion part 12 Bump protection part 13 Recess 14 Semiconductor wafer 15 Street 16 Semiconductor chip 17 Peripheral area 18 Notch 19 Bump

Claims (2)

A method of grinding a back surface of a semiconductor wafer having a plurality of bumps formed on the surface,
Peripheral adhesive part that is attached to the outer peripheral region of the semiconductor wafer on which no bumps are formed, a bump protection part that is surrounded by the peripheral adhesive part to support and protect the bump, the outer peripheral adhesive part, and the bump protection Using a protective member that is formed of a concave portion that accommodates the bump,
A protective member disposing step of adhering the outer peripheral adhesive portion of the protective member to the outer peripheral region of the surface of the semiconductor wafer and protecting the bump with the bump protective portion;
A grinding step of holding the protective member side of the semiconductor wafer on the chuck table and grinding the back surface of the semiconductor wafer with a grinding means;
A method for grinding a semiconductor wafer comprising: A protective member for protecting the back surface of a semiconductor wafer having bumps formed on the surface,
Peripheral adhesive part that is attached to the outer peripheral region of the semiconductor wafer on which no bumps are formed, a bump protection part that is surrounded by the peripheral adhesive part to support and protect the bump, the outer peripheral adhesive part, and the bump protection A recess that is formed by a portion and accommodates the bump;
A bump protecting member for grinding composed of

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