JP5041692B2 - Wafer with special shape crystal orientation identification - Google Patents

Description

  The present invention relates to a wafer on which an identification portion for identifying a crystal orientation is formed.

  As shown in FIGS. 9 and 10, the wafers 5 and 6 in which a plurality of devices D such as IC and LSI are formed on the respective surfaces 50 and 60 are divided into individual devices by a dividing device such as a dicing device, Used in various electronic devices.

  In order to reduce the size and weight of electronic devices, the wafer is formed with a very thin thickness of 50 μm or less or 30 μm or less by grinding the back surface, so that handling such as subsequent conveyance is not easy. There's a problem.

  Therefore, when the present applicant grinds the back surface of the wafer to form a thin wafer, only the back surfaces of the device regions 51 and 61 where the device D is formed in the wafers 5 and 6 shown in FIGS. 9 and 10. The outer peripheral surplus regions 52 and 62 on the outer peripheral side of the device regions 51 and 61 are not ground but formed to have a ring-shaped reinforcing portion, and handling such as subsequent conveyance of the thinned wafer is performed. A patent application was filed for an invention that facilitates this (Japanese Patent Application No. 2005-165395). At this time, no publicly known literature similar to the invention can be found.

  However, a crystal orientation identifying portion for identifying the crystal orientation is formed on the wafer from the outer peripheral surplus regions 52 and 62 to the device regions 51 and 61. Specifically, in the wafer 5 shown in FIG. 9, an orientation notch 53 on the notch is formed as a crystal orientation identification portion. In the wafer 6 shown in FIG. 10, an orientation flat 63, which is a flat surface, is formed as a crystal orientation identification portion. In any of the wafers, the crystal orientation identification portion is formed by cutting out part of the outer peripheral surplus regions 52 and 62 and reaches the device regions 51 and 61, so the back side of the device regions 51 and 61 is ground. Then, the ground portion reaches the orientation notch 53 or the orientation flat 63, and there is a problem that sufficient reinforcement cannot be achieved even if the outer peripheral surplus regions 52 and 62 remain.

  Therefore, the problem to be solved by the present invention is that the portion corresponding to the device region of the back surface of the wafer is ground to form a ring-shaped reinforcing portion on the outer peripheral side thereof, and is not affected by the crystal orientation identification portion. It is to secure sufficient strength by the ring-shaped reinforcing part.

A first invention constituting the present invention is a wafer in which a plurality of devices are formed , a device region in which the device is formed, and an outer peripheral surplus region that is located on the outer peripheral side of the device region and in which no device is formed. The device region is ground on the back side to form a recess, and the outer periphery of the recess is formed with a ring-shaped reinforcing portion that maintains the thickness before grinding, and the crystal orientation identification portion protrudes from the outer peripheral side surface of the wafer. It is characterized by being formed.

A second invention constituting the present invention is a wafer in which a plurality of devices are formed , a device region in which the device is formed, and an outer peripheral surplus region that is located on the outer peripheral side of the device region and in which no device is formed. A back surface side of the device region is ground to form a recess, a ring-shaped reinforcing portion having a thickness before grinding is formed on the outer periphery side of the recess , a chamfered portion is formed in the outer periphery surplus region, and a chamfer is formed. A concave crystal orientation identification portion having a depth equal to or smaller than the width of the chamfered portion is formed from the side surface of the portion toward the center of the wafer.

  In the second invention, the depth of the concave crystal orientation identification portion is preferably 0.5 mm or less.

A wafer in which the crystal orientation identification portion protrudes from the outer peripheral side surface of the wafer, or a concave crystal orientation identification portion having a chamfered portion formed in the outer peripheral surplus area and having a depth less than the width of the chamfered portion from the side surface of the chamfered portion. In the formed wafer, the crystal orientation identification part is formed in a state that does not reach the device region. Therefore, even if the portion corresponding to the device region in the back surface is ground to a desired thickness, it is ground. Since this portion does not reach the crystal orientation identification portion, sufficient strength can be secured by the ring-shaped reinforcing portion.

  First, a wafer 1 shown in FIG. 1 will be described as a first example of the present invention. A plurality of devices D are formed on the surface 10 of the wafer 1 shown in FIG. 1 by being partitioned by streets S formed vertically and horizontally. The inner part of the two-dot chain line on which the device D is formed constitutes the device region 12. On the outer peripheral side of the device region 12, an outer peripheral surplus region 13, which is a portion where no device is formed, is formed.

  From the outer peripheral side surface 14 of the wafer 1, the orientation convex part 15 which is a crystal orientation identification part protrudes toward the outer peripheral side. This orientation convex part 15 can be formed by, for example, leaving a part of the ingot without polishing when polishing the outer periphery of the ingot to adjust the cross section to a circle.

  The wafer 1 is formed to have a desired thickness by grinding the back surface 11 shown in FIG. 2, but before the back surface 11 is ground, the protective tape 3 is attached to the front surface 10 as shown in FIG. Is done. Then, for example, the back surface is ground using a grinding device 4 shown in FIG.

  The grinding apparatus 4 includes a chuck table 40 that holds a wafer, and a grinding unit 41 that performs grinding on the wafer held on the chuck table 40. The grinding part 41 includes a rotating shaft 42 having a vertical axis, a wheel 43 attached to the lower end of the rotating shaft 42, and a grindstone 44 fixed to the lower surface of the wheel 43. The wafer 1 is in a state where the protective tape 3 side is held by the chuck table 40 and the back surface 11 is exposed.

  Then, as the chuck table 40 rotates and the grinding part 41 descends while the wheel 43 rotates, the rotating grindstone part 44 contacts the back surface 11 of the wafer 1 to perform grinding. At this time, the grindstone 44 is brought into contact with the back side of the device region 12 (see FIG. 2) formed on the front surface 10 of the wafer 1, and the outer peripheral side is not ground. Then, when the desired amount of the back side of the device region 12 is ground, the grinding is finished.

  Thus, by grinding only the region corresponding to the device region 12 in the back surface 11, a recess 16 is formed on the back surface side of the device region 12 as shown in FIGS. The ring-shaped reinforcement part 17 which maintained the thickness before grinding is formed. For example, the width of the ring-shaped reinforcing portion 17 may be about 2 to 3 mm. Further, the thickness of the ring-shaped reinforcing portion 17 is preferably several hundred μm. On the other hand, the thickness of the device region 12 can be reduced to about 30 μm.

  In the wafer 1 shown in FIG. 4, the orientation convex portion 15 is formed so as to protrude to the outer peripheral side. Therefore, even if the back surface side of the device region 12 is ground, the ground portion does not reach the orientation convex portion 15. Sufficient reinforcement is made by the ring-shaped reinforcing portion 17 maintaining the original thickness, and subsequent handling such as transportation becomes easy.

  Next, a wafer 2 shown in FIG. 5 will be described as a second example of the present invention. Similar to the wafer 1 shown in FIG. 1, a plurality of devices D are formed on the surface 20 of the wafer 2 shown in FIG. 5, partitioned by streets S formed vertically and horizontally. An inner portion of the two-dot chain line formed with the device D forms a device region 22. On the outer peripheral side of the device region 22, an outer peripheral surplus region 23, which is a portion where no device is formed, is formed.

  In a part of the outer peripheral side surface 24 of the wafer 1, an orientation concave portion 25 which is a crystal orientation identification portion is formed in a concave shape toward the center direction of the wafer 2. The orientation recess 25 can be formed, for example, by polishing the outer periphery of the ingot to adjust the cross section to a circle and then polishing a part thereof.

  As shown in FIG. 6, the outer peripheral side surface 24 of the wafer W is chamfered, and a chamfered portion 28 having a semi-circular, semi-elliptical cross section, etc. is formed. The width L of the chamfered portion 28 is about 1 to 2 mm from the outermost side surface 24 toward the center of the wafer W. The chamfered portion 28 is formed in the outer peripheral surplus region 23 and reaches the device region 22. Not.

  The orientation recess 25 has a depth D equal to or less than the width L of the chamfered portion. When the width L of the chamfer 28 is 1 mm, the depth of the orientation recess 25 is 0.5 mm or less toward the center of the wafer W.

  The wafer 2 is formed to have a desired thickness by grinding the back surface 21 shown in FIG. 7. Before the back surface 21 is ground, the protective tape 3 is attached to the front surface 20 as shown in FIG. Is done. Then, for example, the back surface is ground using the grinding device 4 shown in FIG. The grinding method is the same as that for the wafer 1.

  By grinding only the region corresponding to the device region 22 in the back surface 21, a recess 26 is formed on the back surface side of the device region 22 as shown in FIG. A ring-shaped reinforcing portion 27 that maintains the thickness is formed.

  In the wafer W shown in FIG. 8, the orientation concave portion 25 is formed in a concave shape toward the center side of the wafer W, but the depth thereof is smaller than the width of the chamfered portion 28, and the chamfered portion 28 is formed in the outer peripheral surplus region 23. Since it is formed and does not reach the device region, even if the back surface side of the device region 22 is ground, the ground portion does not reach the orientation concave portion 25, so the ring-shaped reinforcing portion 27 that maintains the original thickness is used. Sufficient reinforcement is provided, and subsequent handling such as transportation becomes easy.

It is a top view which shows an example of the wafer in which the crystal orientation identification part protrudes from the outer peripheral side surface of a wafer. It is a perspective view which shows the state which sticks a protective tape on the surface of the wafer. It is a perspective view which shows the state which grinds the part corresponded to a device area | region among the back surfaces of the wafer. It is sectional drawing which shows the state after grinding of the wafer. It is a top view which shows an example of the wafer in which the chamfered part is formed in the outer periphery and the concave crystal orientation identification part which has the depth below the width | variety of a chamfered part from the side surface of a chamfered part is formed. It is the sectional view on the AA line of FIG. It is a perspective view which shows the state which sticks a protective tape on the surface of the wafer. It is sectional drawing which shows the state after grinding of the wafer. It is a top view which shows the wafer in which the orientation notch was formed. It is a top view which shows the wafer in which orientation flat was formed.

Explanation of symbols

1: Wafer 10: Front surface D: Device S: Street 12: Device region 11: Back surface 16: Concave portion 13: Peripheral surplus region 14: Peripheral side surface 15: Orientation convex portion 17: Ring-shaped reinforcing portion 2: Wafer 20: Front surface D: Device S: Street 22: Device region 21: Back surface 26: Recessed portion 23: Outer peripheral surplus region 24: Outer peripheral side surface 25: Orientation concave portion 27: Ring-shaped reinforcing portion 28: Chamfered portion

3: Protection tape 4: Grinding device 40: Chuck table 41: Grinding part 42: Rotating shaft 43: Wheel 44: Grinding wheel part

Claims (3)

A wafer formed with a plurality of devices,
A device region where a device is formed, and an outer peripheral surplus region which is located on the outer peripheral side of the device region and where no device is formed;
The back side of the device region is ground to form a recess, and the outer periphery of the recess is formed with a ring-shaped reinforcing portion that maintains the thickness before grinding,
A wafer in which a crystal orientation identification portion protrudes from the outer peripheral side surface of the wafer. A wafer formed with a plurality of devices,
A device region where a device is formed, and an outer peripheral surplus region which is located on the outer peripheral side of the device region and where no device is formed;
The back side of the device region is ground to form a recess, and the outer periphery of the recess is formed with a ring-shaped reinforcing portion that maintains the thickness before grinding,
The peripheral marginal region chamfered portion is formed on a wafer of crystal orientation identification section of the concave is formed to have a width less than a depth of the chamfered portion toward the side surface of the chamfer in the direction of the center of the wafer. The wafer according to claim 2, wherein a depth of the concave crystal orientation identification portion is 0.5 mm or less.

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