JP2006339373A - Groove forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a groove forming method capable of forming a groove having no blur on edge portions by efficiently eliminating blurs formed of a metal film generated on both the edge portions of a grinding groove in forming the grinding groove on a ductile material or a work having a ductile material on its surface. <P>SOLUTION: A groove grinding process for forming a predetermined grinding groove GM on the work W is performed using a first grinding stone 21A. After the groove grinding process, a chamfering process for performing chamfering processing on both the edges of the grinding groove GM formed in the groove grinding process using a second grinding stone 21B having a V-shaped tip. The blur B generated on both the edges of the grinding groove in the groove grinding process is eliminated in the chamfering process. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a groove forming method, and more particularly, to a groove forming method for forming a groove in a work having a ductile material or a ductile material layer on a surface.

  In the process of dividing a plate-like workpiece (called a semiconductor wafer) having a large number of semiconductor devices on the surface into individual semiconductor chips, a grinding groove is formed on the workpiece with a thin blade grindstone having a thickness of 20 to 30 μm called a dicing blade. Then, a dicing apparatus that divides the workpiece into individual semiconductor devices (referred to as semiconductor chips) is used.

  On a semiconductor wafer on which a large number of such semiconductor devices are formed, a large number of individual semiconductor chips are arranged in a lattice pattern across a cutting region called a street. In the dicing apparatus, a grinding groove is formed in this street to divide the semiconductor wafer into individual semiconductor chips.

  By the way, an inspection pattern made of a metal film such as copper or aluminum called TEG (Test Element Group) for inspecting the characteristics of an electronic circuit formed on each semiconductor chip is formed on the semiconductor wafer. Some are arranged on the street surface. When dicing a semiconductor wafer having a TEG formed on such a street, the metal film forming the TEG is ground to form a cut groove.

However, since the metal film is a ductile material, burrs made of a whisker-like or band-like metal film are generated at both edges of the grinding groove. The burrs are peeled off in a later process, causing problems such as short-circuiting or damaging the electronic circuit formed on each semiconductor chip. In order to solve this problem, various proposals have been made (see, for example, Patent Document 1).
JP 2001-319897 A

  The method described in the above-mentioned Japanese Patent Application Laid-Open No. 2001-319897 (Patent Document 1) uses a roller scriber to form a scribe groove on a street on which a metal film is formed to divide the metal film, and then turn the semiconductor wafer upside down. Then, the front side is attached to a dicing sheet, and a dicing blade is used to form a grinding groove with a slight uncut portion from the back side, thereby dividing each semiconductor chip.

  According to this method, the metal film formed on the street is divided in advance by a roller scriber, and the grinding groove by the dicing blade formed from the back side has a slight uncut portion, so the metal film is not ground. Can be divided into individual semiconductor chips. Therefore, burrs made of a metal film do not occur.

  However, the method disclosed in Patent Document 1 requires a scribing device in addition to the dicing device. In addition, since the semiconductor wafer is turned upside down and the front side is adhered to the dicing sheet, and grinding grooves are formed from the back side, the semiconductor wafer is turned upside down again in the chip mounting process, which is the next process of the dicing process. The sheet must be reattached on the back side with the top facing up. For this reason, the number of apparatuses used is large, and the manufacturing process is complicated and expensive.

  In addition, there has been conventionally proposed a method in which a metal film formed on a street is burned out with a laser, and then a grinding groove is formed with a dicing blade to divide the semiconductor wafer into individual semiconductor chips. However, this method also requires an expensive laser device, and has the problem that the cost is high like the method described in Patent Document 1 described above.

  The present invention has been made in view of such circumstances, and in forming a grinding groove in a work having a ductile material or a ductile material layer on the surface, a burr made of a metal film generated at the edges on both sides of the grinding groove is formed. It is an object of the present invention to provide a groove forming method capable of efficiently removing and forming a groove having no burr at the edge.

  In order to achieve the above object, the present invention provides a groove forming method for forming a groove in a work having a ductile material or a ductile material layer on a surface with a rotating grindstone. A groove grinding step for forming a predetermined grinding groove on the workpiece, and a second grinding wheel having a V-shaped tip after the groove grinding step, and both of the grinding grooves formed in the groove grinding step. And a chamfering process for chamfering an edge, and a burr formed on both edges of the grinding groove in the groove grinding process is removed in the chamfering process.

According to the first aspect of the present invention, after the groove grinding step for forming the grinding groove, the both edges of the grinding groove are chamfered with the second grindstone having a V-shaped tip, and both of the grinding grooves are formed in the groove grinding step. Since the burr generated at the edge is removed, a groove having no burr at the edge can be formed.

  The invention according to claim 2 is characterized in that, in the invention according to claim 1, the grinding groove is a cutting groove for completely cutting the workpiece, and according to the invention according to claim 2, the grinding groove is cut. There is no burr at the edge of the workpiece.

  According to a third aspect of the present invention, in forming the plurality of grooves in the workpiece according to the first or second aspect of the present invention, two spindles, a first spindle and a second spindle, are provided. The first grindstone is attached to the first spindle and the second grindstone is attached to the second spindle, and the chamfering process of the chamfering process by the second grindstone is performed using the dicing apparatus having the first grindstone. There is provided a groove forming method characterized in that the same line is simultaneously performed with a time difference or with a delay of one line or a plurality of lines with respect to grinding groove processing in the groove grinding step with one grindstone.

  According to the invention of claim 3, by using a dicing apparatus having two spindles, the first grindstone is attached to the first spindle, the second grindstone is attached to the second spindle, and the second grindstone is used. Since chamfering is performed at the same time with a time difference or with a delay of one line or a plurality of lines with respect to the grinding groove processing by the first grindstone, the groove grinding step and the chamfering step can be efficiently performed.

  As described above, according to the groove forming method of the present invention, after the groove grinding step of forming the grinding groove on the workpiece, the chamfering process is performed on both edges of the grinding groove with the second grindstone having a V-shaped tip. Since burrs generated at both edges of the grinding grooves in the groove grinding process are removed, grooves having no burrs at the edges can be formed in the workpiece.

  Hereinafter, a preferred embodiment of a workpiece cutting method according to the present invention will be described in detail with reference to the accompanying drawings. In each figure, the same number or symbol is attached to the same member.

  First, the outline of the dicing apparatus will be described. FIG. 1 is a perspective view showing the appearance of the dicing apparatus. The dicing apparatus 10 includes a load port 60 that transfers a cassette containing a plurality of workpieces to and from an external device, a workpiece conveying means 50 that has a suction portion 51 and conveys the workpiece to each part of the device, An imaging means 81 that images the surface of a workpiece to evaluate the machining state, a machining unit 20, a spinner 40 that cleans and dries the workpiece after machining, and a controller 90 that controls the operation of each part of the apparatus. Has been.

  The processing unit 20 is a part that performs grooving or cutting on the workpiece. The processing unit 20 is provided with two high-frequency motor built-in type air bearing spindles 22A and 22B, which are arranged opposite to each other and attached with thin blades 21A and 21B at the tips, both of which are 30,000 rpm to In addition to being rotated at a high speed of 60,000 rpm, the index feed in the Y direction and the cut feed in the Z direction are performed independently of each other. In addition, the work table 23 on which the work is sucked and placed is configured to be rotatable about an axis in the Z direction, and is configured to be ground and fed in the X direction in the drawing by the movement of the X table 30. .

  FIG. 2 is a perspective view showing the structure of the processing unit 20. As shown in FIG. 2, a spindle 22A having a spindle shaft 22a to which a grindstone 21A is attached at the tip is suspended and held on the Z table 26A via a holding block 29A.

  The Z table 26A is guided by Z guides 28, 28 provided on the Y table 25A, and is driven in the Z direction, which is a cutting feed direction, by a ball screw and a stepping motor (not shown).

  Similarly, a spindle 22B having a spindle shaft 22b to which a grindstone 21B is attached at the tip is suspended and held on a Z table 26B opposite to the spindle 22A via a holding block 29B.

  The Z table 26B is also driven in the Z direction, which is the cutting feed direction, by a ball screw and a stepping motor (not shown) guided by Z guides 28, 28 provided on the Y table 25B.

  The Y table 25A and the Y table 25B are guided by Y guides 27 and 27 provided on the Y base 24, and are independently driven in the Y direction which is an index feed direction by a ball screw and a stepping motor (not shown). .

  In the driving in the Z direction and the Y direction, feedback control is performed by a position signal from a linear scale (not shown), and the spindle 22A and the spindle 22B are precisely driven in the Y direction and the Z direction, respectively. On the other hand, in the X direction that is the grinding feed direction, there is an X table 30 that is driven by an X guide and a linear motor (not shown), and a work table 23 on which a work is placed is incorporated.

  The upper surface of the work table 23 is formed of a porous member for adsorbing and placing the work. The work table 23 is also rotationally driven in the θ direction by the θ table 31, and is positioned at a reference position (CH1 position) and a position rotated 90 degrees (CH2 position).

  As described above, in the processing unit 20, the grindstones 21A and 21B independently perform the Z-direction cutting feed and the Y-direction index feed, and the workpiece is fed in the X-direction grinding feed and the θ-direction. Rotation feed is performed.

  The same kind of grindstone is used as the thin-blade grindstones 21A and 21B, and two lines are cut at the same time to increase the dicing efficiency. Each of the two air-bearing spindles 22A and 22B is different. It is also possible to attach a grindstone and apply special processing.

  As shown in FIG. 6, the work is mounted on the frame F via the dicing sheet S and supplied to the dicing apparatus 10. Next, the workpiece is placed on the work table 23 by the workpiece conveying means 50, the surface pattern is imaged by the imaging means 81, and is subjected to image processing and alignment by an image processing device (not shown).

The aligned workpiece W is diced by the grindstones 21A and 21B in the processing unit 20, and conveyed to the spinner 40 by the workpiece conveying means 50, where it is spin-cleaned and spin-dried. The dried workpiece W is stored in a cassette set in the load port 60 by the workpiece transfer means 50.
Next, an embodiment of a groove forming method according to the present invention using this dicing apparatus 10 will be described. FIG. 3 is a flowchart showing an embodiment of the groove forming method of the present invention, and FIG. 4 is a conceptual diagram thereof. In the present embodiment, the workpiece W is a semiconductor wafer made of a silicon material, and a metal film m that is a ductile material layer is formed on the surface.

  First, the surface side of the workpiece W on which a pattern such as an electronic circuit is formed is attached to a dicing sheet S having an adhesive layer formed on one side, and the workpiece W is mounted on an annular frame F through the dicing sheet S. (Step S1).

  Next, the work W together with the frame F is placed on the work table 23 of the dicing apparatus 10 and the surface side of the work W is sucked and fixed. Next, the pattern formed on the surface of the workpiece W is photographed by the imaging unit 81 from the surface side of the workpiece W, and the workpiece W is aligned based on this pattern. The alignment method is an alignment method using image processing. Since an alignment method using image processing is generally well known, description thereof is omitted (step S2).

  Next, a grinding groove is formed at a depth slightly cut into the dicing sheet S by the first grindstone 21A rotating at a high speed from the surface side of the workpiece W, and the workpiece W is completely cut (full cut) (step S3). This is a groove grinding process, and FIG. 4A shows this state.

  At this time, as shown in FIG. 4B, since the metal film m formed on the surface of the workpiece W is ground, burrs B of the metal film m are generated on both upper edges of the grinding groove GM. The burrs B of the metal film m cannot be removed by a subsequent spin cleaning process.

  Next, as shown in FIG. 4C, chamfering is performed on the upper both edges of the grinding groove GM formed in the groove grinding process in step S3 using a second grindstone 21B having a V-shaped tip (chamfering). Process). By this chamfering process, as shown in FIG. 4D, the burrs B formed on the upper both edges of the grinding groove GM are removed.

  As the tip angle of the second grindstone 21B is obtuse, the deburring effect is higher when chamfering and the chipping of the silicon material is less, but the pattern of the electronic circuit or the like is formed on the surface of the workpiece W. It is necessary to perform chamfering grinding with a width that does not hang over. Therefore, the tip angle of the second grindstone 21B is preferably about 30 ° to 60 ° (step S4).

  Through the above-described steps, a plurality of grinding grooves GM, which are a plurality of cutting grooves, are formed in one direction (CH-1) of the workpiece W. Similarly, a plurality of grinding grooves GM are also formed in the other direction (CH-2) perpendicular to 90 °. By forming, the workpiece W can be divided into individual semiconductor chips T. The edge of the upper surface of the semiconductor chip T divided in this way is slightly chamfered to form a smooth surface from which the burrs B made of the metal film m are removed.

  When the groove grinding process in step S3 and the chamfering process in step S4 are performed, as shown in FIG. 5, the first grindstone 21A is attached to the spindle shaft 22a of the spindle 22A of the dicing apparatus 10, and the spindle shaft of the spindle 22B. The second grindstone 21B is attached to 22b, and the chamfering process in step S4 is preferably ground simultaneously with a slight time difference from the grinding groove forming process in step S3, or with a delay of one line or a plurality of lines. (FIG. 5 is shown with a delay of two lines).

  Thereby, the groove grinding process of step S3 and the chamfering process of step S4 can be performed by a series of operations, and the alignment process for the chamfering process of step S4 is not necessary, and is required for the groove grinding process and the chamfering process. Time can be significantly reduced. The above is the process flow of the work groove forming method according to the embodiment of the present invention.

  As described above, according to the groove forming method of the present invention, since the upper both edges of the grinding groove are chamfered after the grinding groove forming process, the metal film m generated on both edges of the groove when the grinding groove is formed. The burr B is removed by chamfering, and a smooth edge is obtained.

  In the above-described embodiment, the workpiece W is a semiconductor wafer having a metal film m formed on the surface. However, the present invention is not limited to this, and the grooving process or cutting process of a ductile material is also applicable. The effect can be demonstrated.

A perspective view showing a dicing apparatus The perspective view showing the structure of the process part of a dicing apparatus The flowchart explaining embodiment of the groove | channel formation method which concerns on this invention The conceptual diagram explaining embodiment of the groove | channel formation method which concerns on this invention Conceptual diagram explaining an efficient implementation method of the present invention A perspective view showing a state in which a work is mounted on a frame

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Dicing apparatus, 20 ... Processing part, 21A ... 1st grindstone, 21B ... 2nd grindstone, 22A ... 1st spindle, 22B ... 2nd spindle, B ... Burr, F ... Frame, GM ... Grinding groove , M ... metal film (ductile material layer), S ... dicing sheet, T ... semiconductor chip, W ... work

Claims (3)

In a groove forming method for forming a groove in a work having a ductile material layer or a ductile material layer on a surface with a rotating grindstone,
A groove grinding step of forming a predetermined grinding groove on the workpiece using a first grindstone;
A chamfering step of chamfering both edges of the grinding groove formed in the groove grinding step using a second grindstone having a V-shaped tip after the groove grinding step;
A groove forming method, wherein burrs generated at both edges of the grinding groove in the groove grinding step are removed in the chamfering step.   The groove forming method according to claim 1, wherein the grinding groove is a cutting groove for completely cutting the workpiece. In forming a plurality of the grooves in the work,
Using a dicing apparatus having two spindles, a first spindle and a second spindle,
Attaching the first grindstone to the first spindle and attaching the second grindstone to the second spindle;
The chamfering process of the chamfering process by the second grindstone is performed simultaneously with a time difference, or by a delay of one line or a plurality of lines with respect to the grinding groove machining of the groove grinding process by the first grindstone. The groove forming method according to claim 1 or 2, characterized in that:

Images