JP5896607B2 - Wafer manufacturing method and wafer transport method - Google Patents

Description

The present invention relates to a method for manufacturing a wafer having a circular concave portion and an annular convex portion surrounding the circular concave portion, and a wafer conveying method for conveying the wafer.

  In a semiconductor device manufacturing process, a plurality of regions are partitioned by dividing lines called streets arranged in a lattice pattern on the surface of a substantially wafer-shaped semiconductor wafer, and ICs, LSIs, and the like are divided into the partitioned regions. Form the device. Then, the semiconductor wafer is divided into individual semiconductor chips (devices) by cutting the semiconductor wafer along a street with a cutting device.

  A wafer to be divided into individual chips is ground to a predetermined thickness by grinding the back surface before cutting along the street. In recent years, in order to achieve a reduction in weight and size of electrical equipment, it has been required to make the wafer thinner, for example, about 50 μm.

  Such thin wafers are difficult to handle and may be damaged during transportation. Therefore, Japanese Patent Application Laid-Open No. 2007-19461 discloses a grinding method in which only the back surface corresponding to the device region of the wafer is ground and an annular convex portion (annular reinforcing portion) is formed on the back surface of the wafer corresponding to the outer peripheral surplus region surrounding the device region. Proposed in the gazette.

  A wafer ground by such a grinding method has a circular concave portion on the back surface of the wafer corresponding to the device region, and the circular concave portion is surrounded by an annular convex portion acting as a reinforcing portion. Conventionally, the bottom surface of the circular recess is directly sucked by a suction pad and transported.

JP 2007-19461 A

  By the way, when the wafer device is an individual semiconductor device, a metal film serving as an electrode is formed on the bottom surface of the circular recess. In such a wafer, when the circular recess is directly sucked and transported by the suction pad, foreign matter (contamination) adheres to the circular recess due to contact with the suction pad, which causes a problem when the metal film is formed.

  On the other hand, in non-contact conveyance using a Bernoulli pad, the negative concave portion of the wafer may bend due to the negative pressure generated and be damaged from the boundary between the circular convex portion and the circular concave portion. There is also difficulty in transporting.

The present invention has been made in view of these points, and an object of the present invention is to provide a method for manufacturing a wafer and a method for transporting a wafer that solve the above-described conventional problems.

According to the first aspect of the present invention, the circular concave portion and the annular convex portion having a predetermined width surrounding the circular concave portion are formed on the back surface , and a plurality of arc-shaped indentations are locally formed on the inner peripheral wall of the annular convex portion. A method of manufacturing a wafer having a portion , wherein the plurality of arc-shaped indentations are obtained by grinding the annular convex portion from the inner peripheral side using a grinding wheel, and reducing the width of the annular convex portion from the predetermined width. A method for manufacturing a wafer is provided, wherein the wafer is formed by having a small width.

According to a second aspect of the present invention, there is provided a wafer transport method for transporting a wafer manufactured by the wafer manufacturing method according to the first aspect by a wafer transport mechanism, the wafer transport mechanism comprising: a swivel arm; A head portion attached to the tip of the arm, a plurality of support members attached to the head portion so as to expand and contract in a radial direction corresponding to the arc-shaped depression, and attached to the tips of the plurality of support members, respectively. A plurality of support fingers, and the plurality of support members are inserted into the plurality of arc-shaped depressions by extending the plurality of support members in the radial direction, respectively, and the head portion is moved to the swivel arm. The plurality of support fingers are brought into frictional contact with the arcuate recesses, and the wafer is conveyed with the plurality of support fingers supporting the inner peripheral wall of the annular convex portion. Method of transporting wafers to is provided.

According to the first aspect of the present invention, foreign matter (contamination) does not adhere to the bottom surface of the circular concave portion during wafer conveyance, and the possibility of breakage from the boundary between the annular convex portion and the circular concave portion during conveyance is reduced. Provided is a wafer manufacturing method including a circular concave portion and an annular convex portion surrounding the circular concave portion on a back surface.

  According to the second aspect of the present invention, there is no risk of foreign matter (contamination) adhering to the bottom surface of the circular concave portion, and the wafer transport method in which the risk of breakage from the boundary between the annular convex portion and the circular concave portion during transport is reduced. Is provided.

It is a surface side perspective view of a semiconductor wafer. It is a back surface side perspective view of the semiconductor wafer by which the protective tape was stuck on the surface. 1 is a perspective view of a grinding apparatus suitable for carrying out the wafer transport method of the present invention. It is a principal part perspective view of a wafer carrying-out mechanism (unloading arm). It is a perspective view which shows a mode that the back surface of the wafer corresponding to a device area | region is ground. It is explanatory drawing of the grinding method of FIG. It is a longitudinal cross-sectional view of the wafer by which the back surface of the wafer was ground by the grinding method of FIG.5 and FIG.6. It is a top view explaining the method of forming the wafer of 1st Embodiment. It is a top view of the wafer of a 1st embodiment. It is a top view of the wafer of a 2nd embodiment. FIG. 11A is a plan view for explaining a method of transporting a wafer, and FIG. 11B is a partial sectional side view thereof. FIG. 12A is a plan view for explaining a wafer transport method, and FIG. 12B is a partial sectional side view thereof. FIG. 13A is a plan view for explaining a method for transporting a wafer, and FIG. 13B is a partial sectional side view thereof.

  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. The 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.

  A protective tape 23 is attached to the surface 11a of the semiconductor wafer 11 by a protective tape attaching process. Therefore, the front surface 11a of the semiconductor wafer 11 is protected by the protective tape 23, and the back surface 11b is exposed as shown in FIG.

  Referring to FIG. 3, there is shown a perspective view of a grinding apparatus 2 suitable for carrying out the wafer forming method and the wafer transport method according to the first embodiment of the present invention. Reference numeral 4 denotes a base of the grinding apparatus 2, and a column 6 is erected on the rear side of the base 4. A pair of guide rails 8 extending in the vertical direction are 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. In the grinding unit 10, a support bracket 34 that supports the housing 20 of the grinding unit 10 is attached to the moving base 12 that moves in the vertical direction along the pair of guide rails 8.

  The grinding unit 10 includes a housing 20, a spindle 22 rotatably accommodated in the housing 20, a motor 24 that rotationally drives the spindle 22, a wheel mount 26 fixed to the tip of the spindle 22, and a detachable attachment to the wheel mount 26. It includes a grinding wheel 28 which is mounted as possible.

  The grinding unit 10 includes a grinding unit feed mechanism 18 including a ball screw 14 and a pulse motor 16 that move the grinding unit 10 up and down along a pair of guide rails 8. When the pulse motor 16 is driven, the ball screw 14 rotates and the moving base 12 is moved in the vertical direction.

  A chuck table mechanism 36 having a chuck table 38 is disposed at an intermediate portion of the base 4. The chuck table 38 is moved in the Y-axis direction between a wafer carry-in / carry-out region and a cutting region facing the grinding unit 10 by a chuck table moving mechanism (not shown). A bellows 40 covers the chuck table mechanism 36.

  Two cassette mounting tables 42 and 44 are integrally formed on the front portion of the base 4, and a cassette 46 for storing a wafer before grinding is mounted on the cassette mounting table 42. A cassette 48 for accommodating the wafer after grinding is placed on the top.

  In addition to the two cassette mounting tables 42 and 44, a wafer transfer robot 50, a positioning mechanism 52 having a plurality of positioning pins 54, a wafer loading mechanism (loading arm) 56, and a wafer carry-out are provided on the front side portion of the base 4. A mechanism (unloading arm) 58 and a spinner cleaning unit 60 having a spinner table 61 are provided.

  Referring to FIG. 4, a perspective view of a main part of a wafer unloading mechanism (unloading arm) 58 is shown. The wafer carry-out mechanism 58 includes a swivel arm 62, a head part 64 attached to the tip of the swivel arm 62, a pair of extendable support members 66 and 68 attached to the head part 64, and support members 66 and 68. It is comprised from the support finger 70 with which the front-end | tip was mounted | worn.

  The support finger 70 is preferably formed from an elastic member such as rubber. The pair of support members 66 and 68 are expanded and contracted with respect to the head portion 64 by, for example, an air cylinder accommodated in the head portion 64.

  Next, a grinding method for forming a circular concave portion and an annular convex portion surrounding the circular concave portion on the back surface 11b of the semiconductor wafer 11 will be described with reference to FIGS. As shown in FIG. 5, the grinding wheel 28 includes a base 30 and a plurality of grinding wheels 28 arranged annularly on the outer periphery of the lower end of the base 30.

  The wafer 11 is suction-held on the protective tape 23 side by the chuck table 38, and the back surface 11 b of the wafer 11 is set to face the grinding wheel 32. Here, the relationship between the wafer 11 held on the chuck table 38 and the grinding wheel 32 mounted on the grinding wheel 28 will be described with reference to FIG.

  The rotation center P1 of the chuck table 38 and the rotation center P2 of the grinding wheel 32 arranged in an annular shape are eccentric, and the outer diameter of the grinding wheel 32 is the boundary line 25 between the device region 17 of the wafer 11 and the outer peripheral surplus region 19. The relationship is such that the grinding wheel 32 which is smaller than the diameter and larger than the radius of the boundary line 25 and which is annularly arranged passes through the rotation center P 1 of the chuck table 38.

  As shown in FIG. 5, while rotating the chuck table 38 in the direction indicated by arrow a at 300 rpm, for example, the grinding wheel 28 is rotated in the direction indicated by arrow b at, for example, 6000 rpm, and the grinding unit feed mechanism 18 is operated. The grinding wheel 32 of the grinding wheel 28 is brought into contact with the back surface of the wafer 11. Then, the cutting wheel 28 is ground by a predetermined amount at a predetermined grinding feed speed.

  As a result, on the back surface of the semiconductor wafer 11, as shown in FIG. 7, a region corresponding to the device region 17 is ground and removed to form a circular recess 72 having a predetermined thickness (for example, 50 μm), and an outer peripheral surplus region. The region corresponding to 19 is left, and an annular convex portion 74 including the outer peripheral surplus region 19 is formed.

  Referring to FIG. 8, there is shown a plan view illustrating a method for forming a wafer according to the first embodiment of the present invention. This forming method uses the grinding wheel 28 used in the circular recess grinding step shown in FIGS.

  That is, while rotating the grinding wheel 28 in the direction of arrow b at, for example, 6000 rpm, the chuck table 38 is moved in the direction of arrow Y without rotating, and the grinding wheel 32 of the grinding wheel 28 is moved to the inner peripheral wall 74a of the annular protrusion 74. Make contact.

  The annular convex portion 74 is ground from the inner peripheral wall 74 a side while the chuck table 38 is processed and fed in the arrow Y direction to form a dent 76 on the inner periphery of the annular convex portion 74. Further, as shown in FIG. 9, a dent 76 is formed on the inner periphery of the annular convex portion 74 on the opposite side of the dent 76. In FIG. 9, the annular protrusion 74 has a predetermined width W1.

  Referring to FIG. 10, a plan view of a wafer 11A according to the second embodiment of the present invention is shown. The wafer 11 </ b> A of the present embodiment has three indentations 78 on the inner peripheral wall 74 a of the annular protrusion 74.

  The indentation 78 is formed by attaching a grinding wheel having a smaller diameter than the grinding wheel 28 to the wheel mount 26. The formation method of the dent part 78 is the same as the formation of the dent part 76 described with reference to FIG.

  Next, with reference to FIG. 11 thru | or FIG. 13, the conveyance method of the wafer 11 of 1st Embodiment which has the two recessed parts 76 in the internal peripheral wall 74a of the cyclic | annular convex part 74 is demonstrated. After the formation of the indented portion 76, the wafer 11 is moved to the wafer carry-in / out region by driving the chuck table moving mechanism, and is carried out from the chuck table 38 by the wafer carry-out mechanism 58.

  This unloading method (conveying method) will be described with reference to FIGS. In FIGS. 11 to 13, in the plan view shown in FIG. 11A and the partial cross-sectional side view shown in FIG. Show.

  As shown in FIG. 11, the swing arm 62 is lowered with the support members 66 and 68 of the wafer carry-out mechanism 58 contracted, and the support fingers 70 at the tips of the support members 66 and 68 are inserted into the circular recesses 72 of the wafer 11. To do.

  Then, the air cylinder accommodated in the head portion 64 is driven to extend the support members 66 and 68 as indicated by an arrow A in FIG. 12B, and the air just before the support finger 70 contacts the indented portion 76. Stop driving the cylinder.

  In this state, as shown in FIG. 13, when the head portion 64 is slightly rotated in the direction of arrow B with respect to the turning arm 62, the support finger 70 comes into frictional contact with the indented portion 76, and the wafer 11 is supported by the support finger 70. be able to.

  After the suction holding of the chuck table 38 is released, the turning arm 62 is raised with the supporting finger 70 supporting the indented portion 76 of the annular convex portion 74, and then turned counterclockwise in FIG. The wafer 11 is transported to the spinner table 61 of the cleaning unit 60, and the support members 66 and 68 are pulled into the head portion 64 by the air cylinder, so that the wafer 11 is placed on the spinner table 61.

  After the wafer 11 is cleaned and spin-dried by the spinner cleaning unit 60, the cleaned wafer 11 is sucked and held by the wafer transfer robot 50 and inserted into a predetermined position of the cassette 48.

  In the above-described embodiment, the example in which the present invention is applied to the semiconductor wafer 11 has been described. However, the wafer is not limited to the semiconductor wafer, and includes other wafers such as a sapphire wafer and a SiC wafer.

  Further, the semiconductor wafer 11 shown in FIG. 1 has a plurality of devices 15 formed on its surface 11a, but the wafer of the present invention includes a wafer cut from an ingot having no device on the surface.

  In addition, in the wafers 11 and 11A of the first and second embodiments described above, the example in which two and three dent portions are formed on the inner peripheral wall of the annular convex portion 74 has been described, but the number of the dent portions is limited to these. Is not to be done. When transporting the wafer 11 </ b> A of the second embodiment shown in FIG. 10, the wafer carry-out mechanism 58 needs to provide three support members corresponding to the angle of the indented portion 78.

2 Grinding apparatus 10 Grinding unit 11 Semiconductor wafer 17 Device area 19 Peripheral surplus area 28 Grinding wheel 32 Grinding wheel 38 Chuck table 58 Wafer unloading mechanism (unloading arm)
62 Revolving arm 64 Head portion 66, 68 Support member 70 Support finger 72 Circular recess 74 Annular protrusion 74b Inner peripheral wall 76, 78 Recessed portion

Claims (2)

This is a method for manufacturing a wafer in which a circular concave portion and an annular convex portion having a predetermined width surrounding the circular concave portion are formed on the back surface, and a plurality of arc-shaped concave portions are locally provided on the inner peripheral wall of the annular convex portion. And
The plurality of arc-shaped indentations are formed by grinding the annular projection from the inner peripheral side using a grinding wheel, and setting the width of the annular projection to a width smaller than the predetermined width. A method for producing a wafer. A wafer transport method for transporting a wafer manufactured by the wafer manufacturing method according to claim 1 by a wafer transport mechanism,
The wafer transport mechanism includes a swivel arm, a head portion attached to the tip of the swivel arm, and a plurality of support members mounted on the head portion so as to be expandable and contractable in a radial direction corresponding to the arcuate recess. And a plurality of support fingers respectively attached to the tips of the plurality of support members,
The plurality of support fingers are respectively inserted into the plurality of arc-shaped depressions by extending the plurality of support members in the radial direction, and the head unit is rotated with respect to the swivel arm to thereby support the plurality of support fingers. The wafer is transported in a state in which the wafer is transported in a state in which the inner peripheral wall of the annular convex portion is supported by the plurality of support fingers.

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