JP5119614B2 - Wafer outer periphery grinding method - Google Patents

Description

  The present invention relates to a wafer outer periphery grinding method for grinding an outer periphery of a wafer such as a semiconductor material or an electronic component material.

  In the manufacturing process of semiconductor devices, electronic components, etc., wafers with semiconductor devices, electronic components, etc. formed on the front side are subjected to probing, dicing, die bonding, wire bonding, etc., and then resin molded. It becomes a finished product such as a semiconductor device or an electronic component.

  In recent years, semiconductor devices and electronic components used in mobile devices such as mobile phones and portable music players and in-vehicle power devices have been made thinner and smaller in order to increase functionality and improve device characteristics. Demand is increasing. For this reason, the demand for ultra-thin wafers of 100 μm or less is increasing for wafers on which semiconductor devices, electronic components, and the like are formed.

  Such an ultra-thin wafer is manufactured by applying a tape that protects a semiconductor device or electronic component to the surface of the wafer on which the semiconductor device or electronic component is formed, and then grinding the back surface (back grinding). The At this time, after the wafer is sliced from the ingot state by a slicing device such as an inner peripheral blade or a wire saw, the outer peripheral portion is prevented as shown in FIG. Is chamfered into a curved surface or a tapered shape. Therefore, if the back grinding is performed as it is, the outer peripheral portion on the back surface side of the wafer becomes an acute angle as shown by E portion in FIG.

  When the wafer outer peripheral part is stored in a cassette or the like with an acute angle and transported to the next dicing process or the like, chipping or chipping occurs in the outer peripheral part, and the wafer breaks or chipping pieces become particles. Cause problems such as remaining on the wafer surface.

As means for solving this problem, there has been proposed a semiconductor device manufacturing apparatus that grinds an outer peripheral portion of a wafer having an acute angle by a grindstone provided inside a dome-shaped holder (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 10-41259

  According to the technique described in Patent Document 1, the wafer outer peripheral portion having an acute angle becomes an obtuse angle in accordance with the angle of the grindstone provided inside the holder, and chipping and chipping of the outer peripheral portion are suppressed. However, the semiconductor element manufacturing apparatus in Patent Document 1 requires a device for removing a new acute angle portion in addition to a normal chamfering device, which increases the equipment cost.

  In addition, since the grindstone is applied to an acute angle portion where chipping or chipping is already likely to occur, the wafer may be damaged during grinding, which causes a decrease in yield.

  The present invention has been made to solve such a problem, and does not produce an acute angle portion in a wafer after back grinding, and has improved yield without causing chipping, chipping, or wafer cracking. It aims to provide a method.

According to a first aspect of the present invention, in the outer periphery grinding step for grinding the outer periphery of the wafer, the outer periphery of the wafer is performed before the back surface grinding step for reducing the thickness of the wafer by grinding the back surface side of the wafer. A wafer outer periphery grinding method in which a corner end surface of the wafer outer peripheral portion end face is ground to a straight shape with a straight grindstone, and then a corner portion between the front surface side and the back surface side is ground to provide a tapered shape at the corner portion. The tapered shape formed on the front surface side of the wafer is smaller than the thickness of the wafer when the back surface grinding process of the wafer is completed, and the tapered shape formed on the back surface side of the wafer is the wafer. Grind to a position where the straight-shaped part of the outer peripheral end face is larger than the thickness of the wafer when the wafer back grinding process is completed. It is being formed.

According to the present invention , before the wafer is back-grinded, the end face of the outer peripheral portion of the wafer is ground into a straight shape by the straight grindstone provided in the chamfering device. The wafer outer peripheral portion ground in a straight shape is ground with a grindstone with tapered corners on the front surface side and the back surface side, or with an inclined grindstone, and becomes a tapered shape. As a result, the corner portion of the end surface of the outer periphery of the wafer that has been ground into a straight shape is further obtuse, and chipping and chipping do not occur. Therefore, it is possible to process a stable wafer with a high yield.
Further, according to the present invention, the corner portion on the surface side of the wafer outer peripheral end surface ground into a straight shape is ground into a tapered shape smaller than the wafer thickness after back grinding. The tapered shape formed at the corner on the back side of the wafer outer peripheral end surface is ground to a position where the straight shape of the outer peripheral portion after forming the tapered shape is larger than the wafer thickness after back grinding. As a result, the taper shape formed on the surface side by back grinding is not ground, so that an acute angle portion does not occur in the wafer after back grinding. Furthermore, since a large taper shape is formed on the back surface side, damage caused by the entry of a grindstone during back grinding is reduced.

According to a second aspect of the present invention, in the first aspect of the invention, the tape for protecting the wafer surface, which is adhered to the front surface side of the wafer, is smaller than the outer diameter of the wafer. Yes.

  This makes it possible to perform stable grinding without interfering with the grindstone to be ground by the tape that protects the wafer surface when grinding the outer peripheral portion of the wafer.

  As described above, according to the wafer peripheral portion grinding method of the present invention, the wafer peripheral portion grinding with improved yield that does not cause an acute angle portion on the wafer after back grinding and does not cause chipping, chipping, or wafer cracking. Is possible.

  Hereinafter, preferred embodiments of a wafer peripheral portion grinding method according to the present invention will be described in detail with reference to the accompanying drawings.

  First, a wafer chamfering apparatus used in the present invention will be described. FIG. 1 is a front view showing a main part of the chamfering apparatus.

  The chamfering apparatus 10 includes a wafer feeding unit 20, a grindstone rotating unit 50, a wafer supply / storage unit (not shown), a wafer cleaning / drying unit, a wafer transfer unit, and a controller that controls operations of each part of the chamfering device.

  The wafer feeding unit 20 includes an X-axis base 21, two X-axis guide rails 22, 22, four X-axis linear guides 23, 23,..., A ball screw and a stepping motor mounted on the main body base 11. It has an X table 24 that is moved in the X direction in the figure by an X axis driving means 25 that is a linear movement axis.

  The X table 24 has two Y-axis guide rails 26, 26, four Y-axis linear guides 27, 27,..., And a Y-axis drive means that is a linear movement shaft composed of a ball screw and a stepping motor (not shown). A Y table 28 that is moved in the Y direction is incorporated.

  The Y table 28 is guided by two Z-axis guide rails 29 and 29 and four Z-axis linear guides (not shown), and is shown by a Z-axis drive means 30 which is a linear movement shaft composed of a ball screw and a stepping motor. A Z table 31 that is moved in the Z direction is incorporated.

  The Z table 31 incorporates a θ-axis motor 32 and a θ spindle 33, and a wafer table (mounting table) 34 on which the wafer W is sucked and mounted is attached to the θ spindle 33, and the wafer table 34 rotates the wafer table. It is rotated around the axis CW in the θ direction in the figure.

  A truing grindstone 41 (hereinafter referred to as a truer 41) used for truing a grindstone for finishing and grinding the outer periphery of the wafer W is attached to the lower portion of the wafer table 34 concentrically with the wafer table rotation axis CW.

  By the wafer feeding unit 20, the wafer W and the truer 41 are rotated in the θ direction in the figure and are moved in the X, Y, and Z directions.

  The grindstone rotating unit 50 is mounted with an outer peripheral grindstone 52, and is mounted on an outer grindstone spindle 51 that is driven to rotate about an axis CH by an outer grindstone motor (not shown), and a turntable 53 disposed above the outer peripheral grindstone 52. The outer peripheral fine spindle 54 and the outer peripheral fine spindle motor 56, the notch rough spindle 60 and the notch coarse motor 62, the notch fine spindle 57 and the notch fine motor 59 are provided.

  A peripheral grinding wheel 55 which is a chamfering grindstone for finish grinding the outer circumference of the wafer W is attached to the peripheral grinding spindle 54.

  A notch rough grinding wheel 61 is attached to the notch rough spindle 60, and a notch fine grinding wheel 58, which is a chamfering grind for finishing grinding the notch portion, is attached to the notch fine spindle 57.

  The outer peripheral processing grindstone 52, the outer peripheral fine grinding grindstone 55, the notch rough grinding grindstone 61, and the notch fine grinding grindstone 58 are formed of any one of a metal bond grindstone, a resin bond grindstone, and a vitrified grindstone.

  In the outer peripheral processing grindstone 52, the outer peripheral fine grinding grindstone 55, the notch rough grinding grindstone 61, and the notch fine grinding grindstone 58, respectively, the groove P that is trued to the desired outer peripheral shape shown in FIG. A groove Q having a desired shape and a straight shape on the front surface side and the back surface side is formed as shown in FIG.

  By the chamfering apparatus having the above configuration, the outer peripheral portion of the wafer is ground.

  Next, a method for grinding the outer periphery of the wafer according to the present invention will be described. FIG. 3 is a side view showing a processing procedure in the first embodiment of the wafer outer periphery grinding method according to the present invention.

  The wafer W manufactured by slicing the ingot with a slicing device such as an inner peripheral blade or a wire saw is subjected to a process such as polishing, and the outer peripheral surface is chipped, chipped, or removed by the chamfering device 10 shown in FIG. In order to prevent wafer breakage, the outer periphery is ground. As shown in FIG. 3A, the outer peripheral portion of the ground wafer W is ground into a curved shape or a tapered shape that reduces the load on the outer peripheral portion due to contact or the like. In this state, processing is performed up to the process before the back grinding process is performed.

  The wafer that has been processed up to the step before the back grinding process is ground by the straight shape portions of the outer peripheral processing grindstone 52 and the outer peripheral fine grinding grindstone 55, and as shown in FIG. The end face is ground into a straight shape.

  At this time, a protective tape (not shown) for protecting the wafer surface is attached to the front side F of the wafer W. The protective tape has an outer diameter smaller than the outer diameter of the wafer W, and does not interfere with the outer peripheral processing grindstone 52 or the outer peripheral fine grinding grindstone 55 when the outer peripheral portion is ground.

  The wafer W whose outer peripheral end face has been ground is ground on the back side B in a back grinding process, and becomes an extremely thin wafer WF. The thickness t of the wafer WF is about 100 μm in the present embodiment.

  Thereby, the outer peripheral end surface of the wafer WF becomes a straight shape, and an acute angle portion is not formed.

  Next, a second embodiment of the wafer peripheral grinding method according to the present invention will be described. FIG. 4 is a side view showing a processing procedure in the second embodiment of the wafer outer periphery grinding method according to the present invention.

  The wafer W manufactured by slicing the ingot with a slicing device such as an inner peripheral blade or a wire saw is subjected to a process such as polishing, and the outer peripheral portion is ground to obtain a curved surface shape as shown in FIG. Or ground into a tapered shape or the like. In this state, processing is performed up to the process before the back grinding process is performed.

  The wafer that has been processed up to the step before the back grinding step is attached with a protective tape on the front side F, and the straight shape portions of the outer peripheral processing grindstone 52 and the outer peripheral fine grinding grindstone 55 are used as shown in FIG. ), The outer peripheral end face is ground into a straight shape.

  The outer peripheral end face of the wafer W ground in a straight shape has a groove K formed on the outer peripheral processing grindstone 52 and the outer peripheral precision grinding grindstone 55, with the corner K1 on the front surface side F and the corner K2 on the rear surface B side, or It is ground by the inclined portion of the groove Q. Thereby, taper shapes C1 and C2 are formed on the front surface side F and the back surface side B of the wafer W, respectively.

  At this time, the sizes of the tapered shapes C1 and C2 are smaller than the thickness t of the wafer WF after the back grinding process.

  As a result, the outer peripheral portion of the wafer WF has an obtuse angle due to the taper C1, and no chipping or chipping occurs. Therefore, it is possible to process a stable wafer with a high yield.

  Next, a third embodiment of the wafer peripheral grinding method according to the present invention will be described. FIG. 5 is a side view showing a processing procedure in the third embodiment of the wafer outer periphery grinding method according to the present invention.

  The wafer W manufactured by slicing the ingot with a slicing device such as an inner peripheral blade or a wire saw is subjected to a process such as polishing, and the outer peripheral portion is ground to have a curved surface shape as shown in FIG. Or ground into a tapered shape or the like. In this state, processing is performed up to the process before the back grinding process is performed.

  The wafer that has been processed up to the process before the back grinding process is attached with a protective tape on the front surface side F, and the straight shape portions of the outer peripheral processing grindstone 52 and the outer peripheral fine grinding grindstone 55 are used as shown in FIG. ), The outer peripheral end face is ground into a straight shape.

  The outer peripheral end face of the wafer W ground in a straight shape has a groove K formed on the outer peripheral processing grindstone 52 and the outer peripheral precision grinding grindstone 55, with the corner K1 on the front surface side F and the corner K2 on the rear surface B side, or It is ground by the inclined portion of the groove Q. Thereby, a taper shape C1 is formed on the front surface side F of the wafer W, and a taper shape C3 is formed on the back surface side B.

  At this time, the size of the taper shape C1 is smaller than the thickness t of the wafer WF after the back grinding process. Further, as shown in FIG. 5C, the taper shape C2 is such that the straight shape of the outer peripheral end face of the wafer W after the taper shape C1 and the taper shape C3 are formed is the thickness of the wafer WF after the back grinding process. It is formed by grinding to a position larger than the length t.

  Thereby, the outer peripheral portion of the wafer WF is further obtuse due to the taper C1, and further, since the large taper shape C3 is formed on the back surface B, damage due to the entry of the grindstone during back grinding is reduced. .

  Next, a fourth embodiment of the wafer outer periphery grinding method according to the present invention will be described. FIG. 6 is a side view showing a processing procedure in the fourth embodiment of the wafer outer periphery grinding method according to the present invention.

  The wafer W manufactured by slicing the ingot with a slicing device such as an inner peripheral blade or a wire saw is subjected to a process such as polishing, and the outer peripheral portion is ground to obtain a curved surface shape as shown in FIG. Or ground into a tapered shape or the like. In this state, processing is performed up to the process before the back grinding process is performed.

  The wafer that has been processed up to the process before the back grinding process is attached with a protective tape on the surface side F, and the straight shape portions of the outer peripheral processing grindstone 52 and the outer peripheral precision grinding grindstone 55 are used in FIG. ), The outer peripheral end face is ground into a straight shape.

  The outer peripheral end face of the wafer W ground in a straight shape has a groove K formed on the outer peripheral processing grindstone 52 and the outer peripheral precision grinding grindstone 55, with the corner K1 on the front surface side F and the corner K2 on the rear surface B side, or It is ground by the inclined portion of the groove Q. Thereby, a taper shape C1 is formed on the front surface side F of the wafer W, and a taper shape C4 is formed on the back surface side B.

  At this time, the size of the taper shape C1 is smaller than the thickness t of the wafer WF after the back grinding process. Further, as shown in FIG. 6C, the taper shape C4 is such that the straight shape of the outer peripheral end surface of the wafer W after the taper shape C1 and the taper shape C4 are formed is the thickness of the wafer WF after the back grinding process. It is formed by grinding to a position that is smaller than the length t and does not overlap the tapered shape C1 and the tapered shape C4.

  Thus, a taper shape C1 is formed on the front surface side and a taper shape C5 is formed on the back surface side on the outer peripheral portion of the wafer WF, and the corner portion becomes an obtuse angle so that no chipping or chipping occurs. Therefore, it is possible to process a stable wafer with a high yield.

  Next, a fifth embodiment of the wafer outer periphery grinding method according to the present invention will be described. FIG. 7 is a side view showing a processing procedure in the fifth embodiment of the wafer outer periphery grinding method according to the present invention.

  The wafer W manufactured by slicing the ingot with a slicing device such as an inner peripheral blade or a wire saw is subjected to a process such as polishing, and the outer peripheral portion is ground to have a curved surface shape as shown in FIG. Or ground into a tapered shape or the like. In this state, processing is performed up to the process before the back grinding process is performed.

  The wafer that has been processed up to the process before the back grinding process is bonded with a protective tape on the front side F, and as shown in FIG. The front surface side F of the W outer peripheral portion is removed to a depth of t1. t1 is larger than the thickness t of the wafer WF after the back grinding process shown in FIG.

  The outer peripheral portion of the wafer W from which the surface side F has been removed to the depth t1 is further removed from the surface side F to the depth t2 by the corner portion of the outer peripheral grinding wheel 55 as shown in FIG. . t1 is larger than the thickness t of the wafer WF after the back grinding process and smaller than t1.

  As a result, the outer peripheral portion of the back-ground wafer WF does not become an acute angle but remains in a flat shape. Therefore, chipping and chipping do not occur, and stable wafer processing with a high yield is possible.

  Further, since the flat shape portion formed on the wafer WF is ground by the peripheral grinding wheel 55, there is no grinding damage on the grinding surface, and the grinding is performed to the position of t2 shallower than t1, so that it is efficiently ground. The

  As described above, according to the wafer outer peripheral portion grinding method according to the present invention, without causing an acute angle portion in the wafer outer peripheral portion after back grinding, during the transfer from the back grinding process to the next process, or in the next process, No chipping, chipping, or wafer cracking occurs. This improves the yield and enables stable wafer processing.

  In this embodiment, a chamfering device is used for grinding the outer peripheral portion of the wafer. However, the present invention is not limited to this, and can be suitably used by another grinding device or the like.

The front view which shows the principal part of a chamfering apparatus. The cross-sectional view which showed the groove part of the grinding wheel. The side view which showed the process sequence in 1st Embodiment of the wafer outer periphery grinding method concerning this invention. The side view which showed the process sequence in 2nd Embodiment. The side view which showed the process sequence in 3rd Embodiment. The side view which showed the process sequence in 4th Embodiment. The side view which showed the process sequence in 5th Embodiment. Sectional drawing which showed the wafer outer peripheral part before and after back grinding.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Chamfering device, 24 ... X table, 28 ... Y table, 33 ... θ spindle, 34 ... Wafer table, 41 ... Truing grindstone (truer), 52 ... Peripheral processing grindstone, 54 ... Peripheral precision spindle, 55 ... Peripheral precision Grinding wheel, 58 ... Notch fine grinding wheel, 61 ... Notch rough grinding wheel, B ... Wafer back side, C1, C2, C3, C4, C5 ... Tapered shape, E ... Sharp angle part, F ... Wafer surface side, K1, K2 ... Corner, P, W ... Groove, W ... Wafer, WF ... Wafer after back grinding

Claims (2)

In the outer peripheral portion grinding step for grinding the outer peripheral portion of the wafer, which is performed before the back surface grinding step for reducing the thickness of the wafer by grinding the rear surface side of the wafer, the outer peripheral end face of the wafer is a straight-shaped grindstone After grinding into a straight shape by grinding the corners of the front and back sides of the wafer outer peripheral end surface to provide a taper shape at the corners ,
The taper shape formed on the front surface side of the wafer is smaller than the thickness of the wafer when the back surface grinding process of the wafer is completed, and the taper shape formed on the back surface side of the wafer is the outer periphery of the wafer. A method for grinding a wafer outer peripheral portion, wherein a straight-shaped portion of a part end surface is formed by grinding to a position where the thickness of the wafer becomes larger than the thickness of the wafer at the time when the wafer back grinding process is completed . Is affixed to the front surface side of the wafer, the tape for protecting the wafer surface, the wafer outer peripheral portion grinding method according to claim 1, characterized in that less than the size of the wafer outer diameter.

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