Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – Of individual circuit component or element
Reexamination Certificate
2002-08-30
2004-05-11
Zarneke, David A. (Department: 2829)
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
Of individual circuit component or element
C324S754090, C324S1540PB, C324S758010
Reexamination Certificate
active
06734691
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a substrate for a probe card used to test a plurality of semiconductor ICs (Integrated Circuits) in a lump.
2. Description of the Background Art
Referring to
FIGS. 1 and 2
, a conventional substrate for a probe card, generally designated with a reference numeral
1
, is used to test a plurality of identical, semiconductor ICs (IC devices hereinafter)
2
formed on a wafer collectively. The probe card
1
includes a substrate
3
formed with a plurality of positioning holes
4
. The positioning holes
4
are adapted to receive pins studded on a prober, not shown, to thereby position the probe card
1
. The substrate
3
has tester terminals
5
formed thereon and connected to the test head of a tester, not shown, in order to transmit signals to and from the tester.
The substrate
3
includes a stack of layers
6
, each of which has a particular pattern of electrically conductive material formed thereon. Those layers are referred to as signal layers. Those conductive patterns connect the tester terminals
5
to signal terminals
7
also formed on the substrate
3
. Probe needles
9
for signals each are soldered or otherwise affixed to a particular needle seat portion
8
assigned to a signal. The needle seat portion
8
functions as transferring a signal from the signal terminal
7
to the probe needle
9
. Each probe needle
9
includes a portion
9
a
covered with electrically insulative film and a contact portion
9
b
. The contact portion
9
b
has its tip contacting a pad positioned on associated one of the IC devices
2
. In this condition, each probe needle
9
transfers a signal output from the tester to the associated IC device
2
and vice versa.
The substrate
3
has tester power supply terminals
10
formed thereon and connected to the tester head, so that a power supply voltage can be fed from the tester to the IC devices
2
. The substrate
3
also includes an electrically conductive plate
11
, which is divided into segments corresponding in number to the IC devices
2
. In the specific, illustrative configuration, the conductive plate
11
is divided into eight segments in accordance with the number of IC devices
2
to be tested at the same time. The segments of the conductive plate
11
each connect the tester power supply terminals
10
to particular power supply terminals
12
, which are arrayed on both sides of the test portion of the substrate
3
, as seen in plan view of FIG.
1
. The top and bottom surfaces in
FIG. 2
of the conductive plate
11
are electrically insulated, so that the conductive plate
11
forms a power supply layer.
Further, probe needles
14
each are soldered or otherwise affixed to a particular needle seat portion
13
assigned to power supply. The needle seat portion
13
transfers an input voltage from the power supply terminal
12
to the probe needle
14
. The probe needle
14
includes a portion
14
a
covered with electrically insulative film and a contact portion
14
b
. The contact portion
14
b
has its tip contacting a power supply pad
15
positioned on associated one of the IC devices
2
, feeding a voltage input from the tester head to the probe needle
14
. To the substrate
3
, affixed is a probe holder
16
formed of a soft material. The probe needles
14
are inserted in the probe holder
16
and positioned thereby.
To test the IC devices
2
formed on the wafer in one lot, i.e. simultaneously, the probe needles
9
and
14
for signals and power supply are respectively brought into contact with the pads for signals, not shown, and the pads
15
for power supply,
FIG. 1
, of the IC devices
2
. In this condition, a power supply voltage fed from the test head is received by the tester power supply terminals
10
. The power supply voltage is then delivered from the power supply terminals
10
to the probe needles
14
via the conductive plate
11
, power supply terminals
12
, and needle seat portions
13
. Finally, the power supply voltage is input to the IC devices
2
via the tips of the contact portions
14
b
contacting the power supply pads
15
of the IC devices
2
.
Subsequently, a test signal is fed from the tester head to each IC device
2
via the associated tester terminal
5
for a signal, the conductive pattern provided on the associated signal layer
6
, the signal terminal
7
, the needle seat portion
8
, the probe needle
9
, and the signal pad of the IC device
2
. The tester will then measure, e.g., a response time from sending the test signal to receiving a signal in response from the individual IC devices to determine whether or not the individual device are acceptable.
A current trend in the semiconductors art is toward the integration of many different kinds of devices including a memory and a CPU (Central Processing Unit) into a single IC device. This kind of IC device generally needs two or more different power supply voltages.
FIG. 3
shows another conventional substrate for a probe card used to test such an IC device. In the figures, the same reference numerals designate the like elements. As shown, the probe card
1
is configured to test four IC devices
2
collectively, which are half as many as the IC devices
2
exemplarily shown in
FIG. 1. A
particular power supply voltage is applied to each of the upper and lower segments in the figure of the segmented conductive plate
11
. In this condition, the tester, not shown, tests the individual IC devices
2
via the probe card
1
with different power voltages supplied.
FIGS. 4 and 5
show still another conventional substrate for a probe card. As shown, the probe card
1
is configured to test eight IC devices at a time, like the probe card
1
shown in FIG.
1
. In this specific configuration, the conductive plate
11
is divided into sixteen segments, which are two times as many as the IC devices
2
. A particular power supply voltage is applied to each of the right and left segments in
FIG. 5
of the segmented conductive plate
11
via the power supply terminals
10
to thereby test the individual IC devices
2
. As shown in
FIG. 6
, the probe card
1
can test even sixteen IC devices
2
simultaneously when the IC devices
2
are of the type fed with only a single power supply voltage.
The conventional probe cards
1
described above have the following problems left unsolved because they have only a single power supply layer each. When two different power supply voltages are necessary, use must be made of longer probe needles
14
, as shown in FIG.
3
. An increase in the length of each probe needle
14
directly translates into an increase in resistance and therefore in noise. This, coupled with a delay in response, makes the result of the test inaccurate and thereby reduces the number of accepted IC devices, decreasing the overall yield of IC devices. Moreover, it is likely that even acceptable IC devices are rejected.
Whereas the probe card
1
shown in
FIG. 4
may solve the problem stated above, it needs a substitute substrate machined that would increase the test cost. Further, the substitute substrate needs a long production time and therefore lacks in adaptability. Moreover, when three or more different power supply voltages are required, the probe needles
14
must also be as long as the probe needles
14
shown in
FIG. 3
, reducing the yield of IC devices.
In an application where the same power supply voltage must be applied to two portions of each IC device to be tested, and an application where the same power supply voltage is fed from a left and a right conductive plate to the IC device via, e.g., the probe needle arrangement of
FIG. 4
for promoting a wide use, any little difference between power supply voltages input to the two conductive plates would make the result of the test erroneous. To solve this problem, it was necessary to feed the power supply voltage from a single conductive plate as in the configuration shown in FIG.
1
. It follows that a widely usable probe card adaptive to various kinds of IC devices with a sin
Katakura Shigeru
Kato Toshiaki
Matsumoto Jun-ichi
Nakamura Yoshimi
Saijyo Masakatu
Nguyen Jimmy
Oki Electric Industry Co. Ltd.
Rabin & Berdo PC
Zarneke David A.
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