Cutting – Processes
Reexamination Certificate
2002-05-03
2004-12-07
Shoap, Allan N. (Department: 3724)
Cutting
Processes
C083S073000, C083S279000, C451S006000, C451S190000, C125S013010
Reexamination Certificate
active
06826986
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a sawing system having a plurality of rotating saw blades adapted to cut or saw, substrates or semiconductor wafers, in two opposite directions of relative movement at a sawing zone, and more particularly to a sawing system having a vision zone incorporated between a loading/unloading zone and the sawing zone.
BACKGROUND OF THE INVENTION
A singulation saw, hereinafter referred to as a sawing system, for sawing either substrate or semiconductor wafers using a pair of counter rotating saw blades is disclosed in co-pending patent application Ser. No. 09/849,049 titled “BI-DIRECTIONAL SINGULATION SAW AND METHOD” filed on May 5, 2001, and assigned to the same assignee as the present patent application, and which is incorporated herein by reference thereto.
With reference to
FIG. 1
, the disclosed sawing system
100
is coupled to a prior art handler
105
, and the disclosed sawing system
100
primarily comprises three processing zones. The three processing zones are physically arranged relative to each other with a sawing zone
110
located between a loading/unloading zone
115
, and a vision zone
120
. A dual spindle counter rotating saw
125
is used in the sawing zone
110
, and a vision system
129
that employs a camera is employed in the vision zone
120
.
A transport system transports the substrates or semiconductor wafers between the unloading/unloading zone
115
, the sawing zone
110
, and the vision zone
120
; and the transport system also transports the substrates or semiconductor wafers in a reciprocating movement during the sawing process in the sawing zone
110
. The transport system comprises a pair of linear transport means that transport two rotatable carrier supports
122
and
124
along transport paths
129
and
130
, respectively. Each of the two rotatable carrier supports
122
and
124
are adapted for loading a removable carrier thereon. The substrates or semiconductor wafers for sawing are removably mounted on one such carrier.
During the sawing process, for example, when singulating a semiconductor wafer, the handler
105
loads a carrier, with the semiconductor wafer thereon, at the loading/unloading zone
115
onto one of the carrier supports
122
of the sawing system
100
. The transport system then transports the wafer past the sawing zone
110
, to the vision zone
120
. After the vision system
129
has captured the necessary images of the wafer for alignment purposes and the like, the transport system then transports the wafer from the vision zone
120
to the sawing zone
110
. At the sawing zone
110
, the wafer is singulated by the dual spindle counter rotating saw
125
, using the alignment information from the vision system. The dual spindle counter rotating saw
125
is movably mounted along the Y and Z axes, and the rotatable carrier support
122
allows the wafer to be sawn along the X and Y axes. When the dual spindle counter rotating saw
125
has completed singulation of the wafer, the singulated wafer is transported by the transport system to the loading/unloading zone
115
, where the carrier with the singulated wafer thereon is unloaded from the carrier support
122
at the loading/unloading zone
115
by the handler
105
.
The transport system can transport two wafers at a time such that, while a first wafer on the carrier support
122
is being singulated in the sawing zone
110
, a second wafer on the other carrier support
124
is transported from the loading/unloading zone
115
to the vision zone
120
, where the necessary images of the wafer are captured. Then, after the first wafer has been singulated in the sawing zone
110
, as the first wafer is being transported from the sawing zone
110
to the loading/unloading zone
115
, the second wafer at the vision zone
120
is transported to the sawing zone
110
and sawing of the second wafer can then begin.
A disadvantage of this arrangement is that the second wafer passes the sawing zone
110
while the first wafer is being sawn. Consequently, as the sawing process involves the use of water to cool the saw blades as well as to wash away debris, the water from the sawing process tends to wet the second wafer, which adversely affects the subsequent imaging of the second wafer in the vision zone
120
.
In order for the transportation system to be able to transport substrates or semiconductor wafers between the loading/unloading zone
115
and the vision zone
120
, the dual spindle counter rotating saw
125
in the sawing zone
110
is mounted on a cantilever arrangement. The cantilevered dual spindle counter rotating saw
125
is movably mounted to travel along a Y-axis relative to the transport system, and also movably mounted to extend along a Z-axis for moving to and away from the substrate or wafer to be sawn. Due to the weight of the dual spindle counter rotating saw
125
, the load on the cantilever varies dependent upon the position of the saw motor assembly along the Y-axis. Consequently, the displacement of the saw assembly away from a reference horizontal plane also varies. Hence, a disadvantage of the cantilever mounted dual spindle counter rotating saw
125
is the tendency of variation in the displacement of the saw blades, and this variation adversely affects the required five micron tolerance for a cut made by the saw blades.
A scrap removal system of the sawing system
100
operates during the sawing process, where water washes various debris in the sawing zone
110
down a debris collection sink to a removable bin, where the debris is separated from the water. The bin containing the debris can then either be emptied and re-attached to the sawing system
100
, or replaced with an empty bin. A disadvantage of this scrap removal system is the need to stop the sawing process prior to removing the bin, in order stop the flow of water and debris to the bin, and allow the bin containing the debris to be physically removed from the sawing system
100
, without spilling water and debris in a production area. Consequently, the need to stop the sawing process reduces the throughput of the sawing system
100
.
BRIEF SUMMARY OF THE INVENTION
The present invention seeks to provide a bi-directional singulation saw and method, which overcomes or at least reduces the abovementioned problems of the prior art.
Accordingly, in one aspect, the present invention provides a bi-directional singulation system for singulation of substrates, the bi-directional singulation system comprising:
a loading/unloading zone for mounting a carrier onto a first movable carrier support located thereat prior to singulation of at least one substrate disposed on the carrier, and the loading/unloading zone for unloading the carrier from the first movable carrier support located thereat after singulation of the at least one substrate;
a sawing zone comprising at least one bi-directional cutting means for singulating at least another substrate on another carrier mounted on a second movable carrier support, while the first movable carrier support is at the loading/unloading zone; and
a vision zone located between the loading/unloading zone and the sawing zone, the vision zone comprising a vision system for imaging the at least one substrate when the first movable carrier support is at the vision zone, while the second movable carrier support is at the sawing zone.
In another aspect the present invention provides a method for singulating substrates with a bi-directional singulation system, the method comprising the steps of:
a) providing a bi-directional singulation system comprising:
a loading/unloading zone for mounting a first carrier onto a first movable carrier support and for unloading the first carrier from the first movable carrier support, and the loading/unloading zone for mounting a second carrier onto a second movable carrier support and for unloading the second carrier from the second movable carrier support;
a sawing zone comprising at least one bi-directional cutting means for singulating at least a first substrate and at least a se
Chua Eng Hwa
Diprinzio Steven John
Lim Ah Beng
Ghassem Alie
Shoap Allan N.
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