JP2010021484A - Grinding method of wafer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grinding method of a wafer for easily peeling a protective tape from the front of the wafer. <P>SOLUTION: The grinding method of the wafer is used for grinding the rear of a wafer having a device region where a plurality of scheduled division lines are formed in a grid on the front and a device is formed in each of a plurality of regions divided by the plurality of scheduled division lines, and a peripheral surplus region surrounding the device region. The grinding method includes: a cutting groove formation process for forming a cutting groove having a depth at least corresponding to the finishing thickness of the wafer in the peripheral surplus region of the wafer; a protective tape bonding process for bonding the protective tape to the front of the wafer; a grinding process of a wafer for holding the wafer on a chuck table of a grinding apparatus with the side of the protective tape located down for grinding the rear of the wafer to form the thickness of the wafer to be a finishing thickness, and for performing separation with a side the external peripheral side of the cutting groove as an ear; and a protective tape peeling process for carrying out the wafer from the chuck table for peeling the protective tape from the front of the wafer with the ear. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a wafer grinding method for grinding a back surface of a wafer.

  A semiconductor wafer in which a number of devices such as IC and LSI are formed on the surface, and each device is partitioned by a line to be divided (street), the back surface is ground by a grinding machine and processed to a predetermined thickness. A dividing line is cut by a cutting device (dicing device) to be divided into individual devices, and the divided devices are used for electric devices such as mobile phones and personal computers.

  A grinding apparatus for grinding a back surface of a wafer includes a chuck table for holding a wafer, and a grinding means on which a grinding wheel having a grinding wheel for grinding the wafer held on the chuck table is rotatably mounted. The wafer can be ground to a desired thickness with high accuracy.

Also, in order to grind the back surface of the wafer, the front side of the wafer on which a large number of devices are formed must be sucked and held with a chuck table, so that a protective tape is attached to the surface of the wafer so as not to damage the device. (See Japanese Patent Laid-Open No. 10-50642).
Japanese Patent Laid-Open No. 10-50642

  After grinding, it is necessary to peel off the protective tape from the wafer surface. However, in order to peel off the protective tape from the surface of the wafer, a trigger for peeling is created on the outer periphery of the protective tape, and the protective tape is peeled from one side of the outer periphery toward the other side of the outer periphery. Because it is pressed by the grinding wheel during backside grinding, it is strongly attached to the front side of the wafer, and as the wafer diameter increases to 300mm and 450mm, it becomes difficult to create a trigger for peeling on the outer periphery of the protective tape. There is a risk of sometimes damaging the wafer.

  The present invention has been made in view of these points, and an object of the present invention is to provide a wafer grinding method capable of easily peeling the protective tape from the surface of the wafer.

  According to the present invention, a plurality of division lines are formed in a lattice shape on the surface, and a device area in which devices are formed in a plurality of areas partitioned by the plurality of division lines, and the device area A wafer grinding method for grinding a back surface of a wafer having an outer peripheral surplus area that surrounds, and forming a cutting groove having a depth corresponding to a finished thickness of the wafer at least in the outer peripheral surplus area of the wafer A protective tape attaching step for attaching a protective tape to the surface of the wafer, holding the wafer on a chuck table of a grinding device with the protective tape side down, and grinding the back surface of the wafer to In addition to forming the thickness into a finished thickness, the wafer grinding process for separating the outer peripheral side from the cutting groove as an ear part, and the chuck table Wafer was unloaded, grinding method of a wafer, characterized by comprising a protective tape peeling step of peeling the protective tape, there is provided with the ear portion from the surface of the wafer.

  According to the present invention, since the outer peripheral side can be separated from the cut groove of the wafer after grinding as an ear part, the protective tape can be easily and reliably peeled from the surface of the wafer by gripping the protective tape together with the ear part.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view of a semiconductor wafer before being processed to a predetermined thickness. A semiconductor wafer 11 shown in FIG. 1 is made of, for example, a silicon wafer having a thickness of 700 μm, and a plurality of streets 13 are formed in a lattice shape on the surface 11a, and a plurality of streets partitioned by the plurality of streets 13 are formed. A device 15 such as an IC or LSI is formed in the region.

  The semiconductor wafer 11 configured as described above includes a device region 17 in which the device 15 is formed, and an outer peripheral surplus region 19 that surrounds the device region 17. A notch 21 is formed on the outer periphery of the semiconductor wafer 11 as a mark indicating the crystal orientation of the silicon wafer.

  According to the wafer grinding method of the present invention, as a first step, the cutting groove 27 having a depth corresponding to at least the finished thickness of the wafer is formed in the excess outer peripheral region 19 of the wafer 11 by the cutting blade 25 of the cutting device.

  When the finished thickness of the wafer 11 whose back surface is ground is, for example, 100 μm, the depth of the cutting groove 27 is, for example, about 110 μm. After forming the cutting grooves 27 in this way, as shown in FIG. 2, a protective tape 23 is attached to the surface of the wafer 11 as a second step.

  Next, an example of a grinding apparatus suitable for implementing the grinding method of the present invention will be described with reference to FIG. Reference numeral 4 denotes a housing of the grinding device 2, and a column 6 is erected on the rear side of the housing 4. A pair of guide rails 8 extending in the vertical direction is fixed to the column 6.

  A grinding unit (grinding means) 10 is mounted along the pair of guide rails 8 so as to be movable in the vertical direction. The grinding unit 10 includes a housing 12 and a support portion 14 that holds the housing 12, and the support portion 14 is attached to a moving base 16 that moves up and down along a pair of guide rails 8.

  Referring also to FIG. 4, the grinding unit 10 includes a spindle 18 rotatably accommodated in a housing 12, a mounter 20 fixed to the tip of the spindle 18, and a screw fastening to the mounter 20. A grinding wheel 22 having a plurality of grinding wheels 24 and a servo motor 26 that rotationally drives the spindle 18 are included.

  The grinding apparatus 2 includes a grinding unit moving mechanism 32 including a ball screw 28 that moves the grinding unit 10 in the vertical direction along a pair of guide rails 8 and a pulse motor 30. When the pulse motor 30 is pulse-driven, the ball screw 28 is rotated and the moving base 16 is moved in the vertical direction.

  A recess 4a is formed on the upper surface of the housing 4, and a chuck table mechanism 34 is disposed in the recess 4a. The chuck table mechanism 34 has a chuck table 36 and is moved in the Y-axis direction between a wafer attachment / detachment position A shown in FIG. 3 and a grinding position B facing the grinding unit 10 by a moving mechanism (not shown). 38 and 40 are bellows. On the front side of the housing 4, an operation panel 42 on which an operator of the grinding device 2 inputs grinding conditions and the like is disposed.

  The grinding operation of the grinding device 2 configured as described above will be described below. The wafer 11 on which the protective tape 23 shown in FIG. 2 is attached is sucked and held with the protective tape 23 facing down on the chuck table 36 positioned at the wafer attachment / detachment position A shown in FIG. Next, the chuck table 36 is moved in the Y-axis direction and positioned at the grinding position B shown in FIG.

  While rotating the chuck table 36 in the direction of arrow a at, for example, 300 rpm with respect to the wafer 11 thus positioned, the grinding wheel 22 is rotated in the same direction as the chuck table 36, that is, in the direction of arrow b at, for example, 6000 rpm. Then, the grinding unit moving mechanism 32 is operated to bring the grinding wheel 24 into contact with the back surface 11 b of the wafer 11.

  Then, the grinding wheel 22 is ground and fed by a predetermined amount at a predetermined grinding feed speed (for example, 3 to 5 μm / second), and the wafer 11 is ground. The wafer is finished to a desired thickness, for example, 100 μm while measuring the thickness of the wafer using a contact-type thickness measurement gauge (not shown). When the grinding process is performed, the grinding streak 31 having a pattern in which a large number of arcs are radially drawn remains on the back surface (surface to be ground) 11b of the wafer 11.

  When the back surface grinding of the wafer 11 is completed, the chuck table moving mechanism is operated to position the chuck table 36 at the wafer attaching / detaching position A shown in FIG. 3, releasing the suction of the chuck table 36 and removing the wafer 11 from the chuck table 36. .

  Since the cutting groove 27 is formed to a depth of 110 μm, when the wafer 11 is finished to a thickness of 100 μm, the cutting groove 27 appears on the back surface 11b of the wafer 11 as shown in FIG. The outer peripheral side is separated as an ear portion 29 from other wafer portions.

  Therefore, as shown in FIG. 5B, the ear tape 29 and the protective tape 23 can be picked at the same time, and the protective tape 23 can be easily and reliably peeled from the surface of the wafer 11. When the protective tape is peeled off, the wafer 11 cut by the cutting groove 27 can be obtained as shown in FIG.

  As described above, according to the wafer grinding method of the embodiment of the present invention, when the protective tape is peeled off from the surface of the wafer, the protective tape is picked up together with the ears separated from the other parts of the wafer and peeled off. Therefore, the protective tape can be easily and reliably peeled off from the surface of the wafer after grinding.

It is a surface side perspective view of a semiconductor wafer showing a cutting groove formation process. It is a disassembled perspective view which shows a mode that a protective tape is stuck on the surface of a wafer. 1 is an external perspective view of a grinding apparatus suitable for carrying out the grinding method of the present invention. It is a perspective view which shows the positional relationship of the grinding wheel and the wafer hold | maintained at the chuck | zipper tape at the time of a grinding process. It is explanatory drawing explaining the peeling process of a protective tape. It is a surface side perspective view of the semiconductor wafer from which the protective tape was peeled off.

Explanation of symbols

2 Grinding device 10 Grinding unit 11 Semiconductor wafer 22 Grinding wheel 23 Protective tape 24 Grinding wheel 27 Cutting groove 29 Ear part 36 Chuck table

Claims (1)

A device area in which a plurality of division lines are formed in a lattice pattern on the surface, and devices are formed in a plurality of areas partitioned by the plurality of division lines, and an outer peripheral surplus area surrounding the device area A method of grinding a wafer for grinding a back surface of a wafer having:
A cutting groove forming step of forming a cutting groove having a depth corresponding to at least the finished thickness of the wafer in the outer peripheral surplus area of the wafer;
A protective tape attaching step of attaching a protective tape to the surface of the wafer;
Hold the wafer on the chuck table of the grinding machine with the protective tape side down, and grind the back surface of the wafer to form a finished wafer thickness, and separate the outer periphery of the cutting groove from the ear The wafer grinding process,
A protective tape peeling step of unloading the wafer from the chuck table and peeling the protective tape together with the ears from the surface of the wafer;
A method for grinding a wafer, comprising:

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