Method and apparatus for cutting a wafer

Details Method and apparatus for cutting a wafer Method and apparatus for cutting a wafer

1999-01-07

2002-03-19

Rachuba, M. (Department: 3724)

Cutting

Other than completely through work thickness or through work...

Combined types of cutting

C083S073000, C083S076100, C083S169000, C083S367000, C083S368000, C083S370000, C125S013010

Reexamination Certificate

active

06357330

ABSTRACT:

BACKGROUND OF THE INVENTION
1). Field of the Invention
This invention generally relates to a wafer cutting apparatus and, more specifically, to a wafer cutting apparatus which includes a saw for cutting a wafer wherein the saw is controlled by a variable of the wafer.
2). Discussion of Related Art
FIG. 1
illustrates a conventional silicon wafer
10
. The manufacture of semiconductor chips involves the formation of a number of integrated circuits
12
on such a silicon wafer
10
. The integrated circuits
12
are usually positioned in a matrix of rows and columns. The integrated circuits
12
are then severed from one another in a subsequent sawing operation.
FIG. 2A
illustrates a portion of a wafer of the above kind having adjacent integrated circuits
12
A and
12
B with a saw street
16
defined between the integrated circuits
12
A and
12
B. A guard ring
18
is made around each integrated circuit
12
A and
12
B. The guard rings
18
form edges of the saw street
16
.
The wafer
10
has an undulating upper surface which may be due to the manufacturing of the integrated circuits
12
A and
12
B or due to mounting of the wafer
10
for purposes of sawing. A V-shaped groove
20
is sawed through the saw street
16
. A sawing blade (not shown) having a V-shaped edge is used for sawing the groove
20
. The sawing blade is progressed through the saw street
16
without compensating for differences in height of the wafer
10
so that the width of the groove
20
varies along its length. Variations in width of the groove
20
may cause severe damage to the guard ring
18
and the integrated circuits
12
.
FIG. 2B
illustrates a portion of a wafer
22
with portions of integrated circuits
24
and
26
, guard rings
28
, and a saw street
30
as in FIG.
2
A. The saw street is made of silicon and one or more objects
32
of a different material than silicon is located in the saw street
30
. The objects
32
are typically made of aluminum, aluminum-copper, tungsten or copper. The objects
32
may include test features such as thickness monitors, resistance monitors, device monitors, fabrication alignment marks etc.
A sawing blade may progress through the silicon saw street
30
without causing major damage to the guard ring
28
. However, when the sawing blade starts sawing through the objects
32
, major damage to the guard ring
28
and the integrated circuits
12
A and
12
B may result. Damage to the guard ring
28
and the integrated circuits
12
A and
12
B is typically in the form of delamination of different layers of the wafer
10
and may be due to a number factors including the material characteristics of the objects
32
, the rotational speed of the sawing blade, the speed at which the sawing blade progresses through to the saw street
30
, the accumulation of debris, plate quality, past usage of the blade or variations in temperature of the wafer
10
while being cut.
SUMMARY OF THE INVENTION
A wafer cutting apparatus which includes a wafer saw, a detector, and a control unit. The wafer saw includes a wafer holder. The detector detects a variable of a wafer being held by the wafer holder. The control unit utilizes the variable to control the saw.


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patent: 6006739 (1999-12-01), Akram et al.
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