JPH0851089A - Dicing method for semiconductor wafer that avoids formation of sliver from cut test pad and die that arises by dicing operation - Google Patents

Abstract

PURPOSE: To prevent a sliver from being formed from a cut test pad by cutting a wafer partially inside along a sheet by using a rotary cutter and forming a groove to be cut through a test pad. CONSTITUTION: A cutter 54 has a cutting edge in an inclined shape with two inclined side surfaces 54a and 54b. The cutter 54 cuts a wafer 40 only partially toward the inside. Then, a groove with two angles or an inclined edge is formed in the wafer 40. When the cutter 54 passes through the test pad 52 is cut, a sliver generated owing to the cutting of the test pad 52 is all compressed into a cutting area and is sheared by the inclined side surfaces 54a and 54b of the cutter 54.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to semiconductor device manufacturing technology, and more particularly to cut test
The present invention relates to a method for dicing a semiconductor wafer that avoids the formation of a sliver from a pad, and a die created by dicing the wafer.

[0002]

BACKGROUND OF THE INVENTION In order to minimize the cost of manufacturing integrated circuits by microelectronics, as many individual integrated circuit dies as possible are made on a single semiconductor wafer. The wafer is then cut using known dicing techniques to separate individual dies.

More particularly, FIG. 1 illustrates a semiconductor wafer 10 having a plurality of individual integrated circuit dies formed thereon. Two adjacent dies 12, 14 are shown in FIG. 1 with microelectronic circuitry formed on their surfaces, designated 13, 15 respectively.

FIG. 1 shows a die 1 with appropriate metallization in such a way that the test pads can be used to test this circuit before the wafer is diced.
A test pad structure 16 is illustrated that includes individual test pads 18, 20, 22, 24, 26, 28 interconnected to 2, 14 circuits.

After the fabrication of the circuits on the wafer 10 is completed, the wafer 10 is cut or diced to separate individual dies. This operation is conventionally accomplished using a rotary cutter that cuts the material of the wafer 10 along a line 30 that extends along the center of the space or street 32 between the individual dies 12,14.

A problem that remains unsolved in the prior art is that cutting along line 30 cuts one or more test pads of structure 16. In this case, the test pads 22 and 28 are cut off. As illustrated in FIG. 2, for example, the cut portion 22a of the test pad 22 has slivers 22b, 22c extending from its cut edge 22d.

The slivers 22b, 22c are formed because the edges 22d are cut in a relatively random manner when cut using a conventional rotary cutter having a rectangular cross section. . This forms sliver 22b, 22c, which is not separated from edge 22d, but rather sliver 22b, 22c is pushed backwards by the straight sides of the blade to create edge 22d.
Stays adhered to.

The dies 12, 14 are packaged and interconnected with circuitry on a printed circuit board (not shown) or other supporting structure during subsequent processing. Under normal conditions, the sliver 22b, 22c does not separate from the edge 22d and causes no problems during the operation of the circuit. The sliver 22b, 22c can ensure separation is avoided by forming a passivation layer for protection or a sealing layer of, for example, silicon dioxide on the surface of the die.

However, the test pad cut in such a way that the sliver extends from it has the military test standard "Mil-STD.883, method 2010".
And are excluded under the visual inspection standards of this standard. Therefore, dies manufactured and diced using conventional methods are unacceptable for military applications, as well as for commercial applications that require the dies to meet similar standards.

A convenient solution to this problem is to employ a dual dicing method in which two cuts are made through the wafer along the lines 34, 36 illustrated in FIG. A cut along line 34 is made at the upper edge of street 32 between test structure 16 and circuitry on die 12. A cut along line 36 is similarly made between test structure 16 and circuitry on die 14.

The dual dicing method solves the sliver generation problem by not cutting any of the test pads in structure 16. However, this dual dicing method is also not applicable to high density microelectronic circuits where the distance between the test pad structure and the circuitry on the adjacent die is less than the thickness of the cutting blade. In many circuits, the spacing is very narrow and providing a sufficiently thin cutting blade is physically impractical.

The use of rotary dicing cutters with beveled edges to suppress the formation of chips of wafer material is known in the art. However, the use of angled cutters to eliminate sliver formation caused by cutting metal test pads has never been attempted in any way.

[0013]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of dicing a semiconductor wafer which prevents the formation of sliver from cut test pads.

More specifically, a plurality of dies are formed on a semiconductor wafer, and test pads are formed in the streets between the dies. This wafer partially cuts the wafer inward along the streets using a first rotary cutter to form a groove for cutting through the test pad, and a second rotary cutter. Is diced by completely cutting the wafer along the groove using.

These rotary cutters are preferably arranged in tandem, so that both cuts can be made in one pass. It has been found that the first rotary cutter has a beveled cutting surface, which imparts a beveled surface to the edges of the die that is cut, thus resulting in sliver removal.

Another object of the present invention is to provide a semiconductor die that is made using the dicing method of the present invention and has no extended metal sliver from a cut test pad.

The die of the present invention includes a substrate and portions of test pads that are cut at the beveled corners of the edge of the substrate.

The above and other objects, features and advantages of the present invention will become apparent to those skilled in the art upon reading the detailed description of the invention described below in conjunction with the accompanying drawings. In the accompanying drawings, similar parts are provided with similar reference numbers.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A method of dicing a semiconductor wafer to create individual dies is illustrated in FIG. A semiconductor wafer 40 having a plurality of individual die formed thereon is mounted on a movable carriage 42 via a layer 44 of releasable tape or other means.

As illustrated in FIG. 4, dies 46, 48 are formed on the wafer 40 and streets 50 are provided between the dies 46, 48. A test pad 52, symbolically representing the test pad structure designated by reference numeral 16 in FIG. 1, is formed in the street 50 between the dies 46, 48.

In accordance with the present invention, wafer 40 is a Disco High T, Santa Clara, Calif., USA.
It is diced using a dicing saw (not explicitly shown) such as DFC-3D / 8, a disco fully automatic dicing saw, commercially available from ech America.

This dicing saw has a carriage 42.
In addition, it has two rotary cutters 54, 56 arranged in tandem as illustrated in FIG. 4 and driven and rotated as shown by the arrow in FIG. Furthermore, the cutters 54, 5
Nozzles 58, 60 are illustrated for ejecting a cooling and lubricating liquid onto the area of the wafer 40 that is cut by each of the six.

The cutters 54, 56 are rotatably driven by electric or hydraulic motors 62, 64 which are normally fixed in a stationary position. The carriage 42 is moved to the right as indicated by arrow 65, which causes the cutters 54, 56 to cut the wafer 40 along a line 66 extending through the center of the street 50. Wafer 40 is cutter 54, 56
As the cutter moves under the test pad 52
Disconnect.

As illustrated in FIG. 5, the cutter 54
Has a beveled cutting edge with two beveled sides 54a, 54b. The cutter 54 only partially cuts the wafer 40 inward as shown in FIG. 5 to form a groove in the wafer 40 having two angled or beveled edges.

According to an important feature of the invention, the cutter 54
When cutting through the test pad 52, any sliver produced by cutting the test pad 52 is compressed into the cutting area and sheared by the sloping sides 54a, 54b of the cutter 54 (shear).
ed off).

By the action of the inclined cutter 54,
The formation of sliver as shown in FIG. 2 is avoided and thus the die made by the dicing method of the present invention
It will meet the above-mentioned military standards.

As illustrated in FIG. 6, blade 56
Are configured to cut into and along the groove formed by the cutter 54. The cutter 54 only partially cuts the inside of the wafer 40, while the cutter 56 completely cuts the wafer 40. This completes the operation of separating the wafer 40 into individual dies.

The cutters 54 and 56 may have the same or different diameters. If a deeper cut is required by the cutter 56, this can be accomplished by choosing the diameter of the cutter 56 to be larger than the diameter of the cutter 54 and / or placing the cutter 56 lower than the cutter 54. It

Next, as illustrated in FIG. 7, the diced portions of the wafer 40 that make up the dies 46, 48 are removed from the tape 44 and the subsequent packaging and interconnection operations are performed. , The integrated circuit of the finished product.

A die diced using the method of the present invention is clearly different from a die diced using prior art methods in that the sliver does not extend from the cut edge of the test pad. There is.

As illustrated in FIG. 7, the die diced using the dicing method according to the present invention further has a unique shape which should be distinguished from that of the prior art. For example, die 46 includes a top surface 46b having the microelectronic circuitry of die 46 and test pads 52 formed thereon.

According to a unique feature of the invention, the die 4
6 also has a vertical edge 46c cut by the cutter 56. The corner 46d that connects the surface 46b with the edge 46c is angled, that is, slanted by the action of the cutter 54. The test pad 52 has a cutting edge 52a cut at a corner 46d by a cutter 54.

FIG. 8 illustrates another form of implementing the method of the present invention. In this embodiment, the side surfaces 54a, 54b
The cutter 54 having a beveled cutting edge defined by is replaced by a rotary cutter 70 having a straight or rectangular cutting edge. Cutter 70
The axis of is inclined by 45 degrees, and the side surface 70a of the cutter 70 is
The adjacent edge 70b extends toward the inside of the wafer 40 and cuts a V-shaped groove as described with reference to FIG.

The present invention is preferably implemented using the two rotary cutters illustrated in FIGS.
However, the present invention provides a single motor, such as 62, with a beveled cutter 54 mounted on the axis of this motor, during the first passage of the cutter 54 down the street 50. Makes a first cut with the cutter 54, then
It can also be realized by removing the cutter 54, installing the cutter 56 on the shaft of the motor, and performing the second cutting using the cutter 56 during the second passage along the street 50.

According to this alternative method, the invention can be implemented using one motor to rotatably drive one cutter, but because the cutting is done in two passes rather than once. It takes twice as long.

Those of ordinary skill in the art, with the understanding of the above description, will be able to make various modifications without departing from the scope of the invention.

[Brief description of drawings]

FIG. 1 is a plan view illustrating a conventional semiconductor wafer including a plurality of dies and a test pad structure formed in a street between the dies.

2 is cut using a prior art dicing method,
FIG. 6 is a plan view illustrating a portion of a test pad having a metal sliver extending from its cut edge.

FIG. 3 is a side view illustrating a dicing method embodying the present invention.

FIG. 4 is a plan view illustrating a dicing method according to the present invention.

FIG. 5 is a sectional view illustrating a dicing method according to the present invention.

FIG. 6 is a sectional view illustrating a dicing method according to the present invention.

FIG. 7 is a sectional view illustrating a dicing method according to the present invention.

FIG. 8 is a cross-sectional view illustrating another form of carrying out the dicing method according to the present invention.

Claims (12)

[Claims] 1. A method of dicing a semiconductor wafer having a die formed above and a test pad formed in a street between the dies, comprising: (a) using a first rotary cutter Cutting the wafer partially inward along the streets to form grooves for cutting through the test pad, and (b) using a second rotary cutter to cut the wafer along the grooves. Completely cutting the wafer. 2. The method of claim 1, wherein the first rotary cutter in step (a) has a cutting edge having two beveled sides. how to. 3. The method of claim 2, wherein step (a) comprises cutting into the interior of the wafer to a depth such that the groove has beveled edges. Method. 4. The method of claim 1, wherein the first and second rotary cutters are arranged in tandem, and steps (a) and (b) are performed on the wafer in parallel with the street. Producing a relative movement between the first and second cutters. 5. The method of claim 4, wherein step (a) is performed during a first passage of the first rotary cutter along the street, and step (b) is the street. A second pass of the second rotary cutter along the. 6. A method of dividing a semiconductor wafer having at least one die formed above, comprising: (a) partially cutting the wafer inward with a first rotary cutter to form a bevel. Forming a groove having a sharp edge, and (b) completely cutting the wafer along the slanted groove using a second rotary cutter. . 7. The method of claim 6, wherein the first
Rotary cutter of claim 1 having a cutting edge with beveled sides. 8. The method of claim 1, wherein the first
And the second rotary cutter is arranged in tandem. 9. The method of claim 8, wherein the step of partially cutting the wafer inward and completely cutting the wafer comprises the steps of: relative to the wafer and the first and second cutters. A method characterized by being performed by causing a physical movement. 10. The method of claim 8, wherein the step of partially cutting is performed during a first pass of the first rotary cutter along the semiconductor wafer. Method. 11. The method of claim 10, wherein the step of completely cutting the wafer is performed during a second pass of the second rotary cutter along the semiconductor wafer. And how to. 12. A semiconductor die comprising: a substrate; and a portion of a test pad formed on a surface of the substrate and cut at an oblique corner of an edge of the substrate.