Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – Of individual circuit component or element
Reexamination Certificate
2002-07-09
2004-03-16
Pert, Evan (Department: 2829)
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
Of individual circuit component or element
C324S754090, C324S758010
Reexamination Certificate
active
06707311
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a contact structure to establish electrical connection with contact targets such as contact pads on semiconductor devices, and more particularly, to a contact structure formed with a flexible cable for use with a probe contact assembly to test semiconductor wafers, IC chips and the like, with high speed, high density and low cost.
BACKGROUND OF THE INVENTION
In testing high density and high speed electrical devices such as LSI and VLSI circuits, a high performance contact structure provided on a probe card must be used. A contact structure is basically formed of a contact substrate (space transformer) having a large number of contactors or probe elements. The contact substrate is mounted on a probe card for testing LSI and VLSI chips, semiconductor wafers, burn-in of semiconductor wafers and dice, testing and burn-in of packaged semiconductor devices, printed circuit boards and the like.
In the case where semiconductor devices to be tested are in the form of a semiconductor wafer, a semiconductor test system such as an IC tester is usually connected to a substrate handler, such as an automatic wafer prober, to automatically test the semiconductor wafer. Such an example is shown in
FIG. 1
in which a semiconductor test system has a test head
100
which is ordinarily in a separate housing and electrically connected to the test system with a bundle of cables
110
. The test head
100
and a substrate handler
400
are mechanically as well as electrically connected with one another with the aid of a manipulator
500
which is driven by a motor
510
. The semiconductor wafers to be tested are automatically provided to a test position of the test head
100
by the substrate handler
400
.
On the test head
100
, the semiconductor wafer to be tested is provided with test signals generated by the semiconductor test system. The resultant output signals from the semiconductor wafer under test (IC circuits formed on the semiconductor wafer) are transmitted to the semiconductor test system. In the semiconductor test system, the output signals are compared with expected data to determine whether the IC circuits on the semiconductor wafer function correctly or not.
In
FIG. 1
, the test head
100
and the substrate handler
400
are connected through an interface component
140
consisting of a performance board
120
(shown in
FIG. 2
) which is a printed circuit board having electric circuit connections unique to a test head's electrical footprint, coaxial cables, pogo-pins and connectors. In
FIG. 2
, the test head
100
includes a large number of printed circuit boards
150
which correspond to the number of test channels (test pins) of the semiconductor test system. Each of the printed circuit boards
150
has a connector
160
to receive a corresponding contact terminal
121
of the performance board
120
. A “frog” ring
130
is mounted on the performance board
120
to accurately determine the contact position relative to the substrate handler
400
. The frog ring
130
has a large number of contact pins
141
, such as ZIF connectors or pogo-pins, connected to contact terminals
121
, through coaxial cables
124
.
As shown in
FIG. 2
, the test head
100
is placed over the substrate handler
400
and mechanically and electrically connected to the substrate handler through the interface component
140
. In the substrate handler
400
, a semiconductor wafer
300
to be tested is mounted on a chuck
180
. In this example, a probe card
170
is provided above the semiconductor wafer
300
to be tested. The probe card
170
has a large number of probe contactors (such as cantilevers or needles)
190
to contact with contact targets such as circuit terminals or contact pads in the IC circuit on the semiconductor wafer
300
under test.
Electrical terminals or contact pads of the probe card
170
are electrically connected to the contact pins (pogo-pins)
141
provided on the frog ring
130
. The contact pins
141
are also connected to the contact terminals
121
of the performance board
120
with the coaxial cables
124
where each contact terminal
121
is connected to the printed circuit board
150
of the test head
100
. Further, the printed circuit boards
150
are connected to the semiconductor test system through the cable
110
having, for example, several hundreds of inner cables.
Under this arrangement, the probe contactors
190
contact the surface (contact targets) of the semiconductor wafer
300
on the chuck
180
to apply test signals to the semiconductor wafer
300
and receive the resultant output signals from the wafer
300
. The resultant output signals from the semiconductor wafer
300
under test are compared with the expected data generated by the semiconductor test system to determine whether the IC circuits on the semiconductor wafer
300
performs properly.
FIG. 3
is a cross sectional view showing an example of structure of a probe contact system formed with a pin block
130
, a probe card
60
, and a contact structure
10
. Typically, the contact structure
10
is formed of a contact substrate (space transformer)
20
having a large number of contactors
30
. In the example of
FIG. 3
, the probe contact system further includes a conductive elastomer
50
between the probe card
60
and the contact structure
10
.
FIG. 3
further shows a semiconductor wafer
300
having contact pads
320
thereon as contact targets. The pin block
130
and probe card
60
in
FIG. 3
respectively correspond to the pogo-pin block (frog ring)
130
and probe card
170
in FIG.
2
.
The pin block
130
has a large number of pogo-pins (contact pins)
141
to interface between the probe card
60
and the performance board
120
(FIG.
2
). At upper ends of the pogo-pins
141
, cables
124
such as coaxial cables are connected to transmit signals to printed circuit boards (pin cards)
150
in the test head
100
in FIG.
2
through the performance board
120
.
The probe card
60
has a large number of contact pads (pogo-pin pads)
65
on the upper surface and contact pads
62
on the lower surfaces thereof. The contact pads
62
and
65
are connected through interconnect traces
63
to fan-out the pitch of the contact structure to match the pitch of the pogo-pins
141
on the pogo-pin block
130
.
The conductive elastomer
50
is to ensure electrical communications between the electrodes
22
of the contact structure and the electrodes
62
of the probe card by compensating unevenness or vertical gaps therebetween. The conductive elastomer
50
is an elastic sheet having a large number of conductive wires in a vertical direction. For example, the conductive elastomer
50
is comprised of a silicon rubber sheet and a multiple rows of metal filaments. The metal filaments (wires) are provided in the vertical direction of
FIG. 3
, i.e., orthogonal to the horizontal sheet of the conductive elastomer
50
.
As shown in
FIG. 3
, the contact structure
10
is basically formed of the contact substrate (space transformer)
20
and a plurality of contactors
30
. The contact structure
10
is so positioned over the contact targets such as contact pads
320
on a semiconductor wafer
300
to be tested that the contactors
30
establish electric connections with the semiconductor wafer
300
when pressed against each other. Although only two contactors
30
are shown in
FIG. 3
, a large number, such as several hundreds or several thousands of contactors
30
are aligned on the contact substrate
20
in actual applications such as semiconductor wafer testing.
The contactors
30
in this example have a beam or finger like shape having a conductive layer
35
made through a semiconductor production process including, for example, photolithography and electroplating processes on a silicon substrate. The contactors
30
can be directly mounted on the contact substrate
20
as shown in FIG.
3
and to form the contact structure
10
which then can be mounted on the probe card
60
through the conductive elastomer
50
. Since the contactors
Advantest Corp.
Muramatsu & Associates
Nguyen Jimmy
Pert Evan
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