Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – Of individual circuit component or element
Reexamination Certificate
2001-10-10
2004-03-23
Pert, Evan (Department: 2829)
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
Of individual circuit component or element
C324S754090
Reexamination Certificate
active
06710615
ABSTRACT:
BACKGROUND OF INVENTION
1. Field of the Invention
The present invention relates to a semiconductor element test apparatus which brings a plurality of probe needles into contact with semiconductor elements fabricated on a semiconductor wafer, as well as to a method of testing a semiconductor element.
2. Background Art
Processes for manufacturing a semiconductor integrated circuit, such as an IC or an LSI, include a test process generally called a wafer test process. As shown in
FIG. 8
, during the course of a wafer test process, there is employed a semiconductor element test device which brings a plurality of probe needles
7
of a probe card
1
attached to a wafer prober
2
into contact with semiconductor elements fabricated on a semiconductor wafer
5
placed on top of a stage
4
. As shown in
FIG. 8
, the wafer prober
2
is provided with a test head
10
, and the test head
10
is connected, by way of a cable
15
, to a tester
3
constituted of a computer.
As shown in
FIG. 9
, the test apparatus performs a test as to whether or not semiconductor elements
6
are non-defective, through the following steps. Namely, the probe needles
7
are brought into contact with respective electrode pads
8
of a plurality of semiconductor elements
6
(i.e., semiconductor chips) fabricated on the semiconductor wafer
5
. In this state, an electrical test input signal is sent to the semiconductor elements
6
from the tester
3
by way of the cable
15
and the probe needles
7
. A test output signal processed by the semiconductor elements
6
is sent back to the tester
3
by way of the probe needles
7
and the cable
15
.
FIG. 10
shows a state of contact between the probe needles
7
and the electrode pads
8
. The stage
4
is pushed up toward the probe needles
7
during a test, and the electrode pads
8
are brought into contact with the probe needles
7
. After completion of the test, the stage
4
is lowered, thereby separating the electrode pads
8
from the probe needles
7
.
FIG. 11
is a side view showing the constitution of the prober
2
while the stage
4
remains in a lowered position.
FIG. 12
is a perspective view showing a probe card
1
having the probe needles
7
mounted thereon.
FIG. 13
is a top view showing the probe card
1
. The prober
2
is equipped with the probe card
1
. The probe card
1
has a probe card substrate
12
which supports the plurality of probe needles
7
. The prober
2
has a test head
10
which operates in cooperation with the probe card
12
. A plurality of probe needles
7
are supported on the lower surface of the probe card substrate
12
, and on the top of the probe card substrate
12
are provided a reinforcement member
13
for reinforcing the probe card substrate
12
, and a plurality of ZIF connectors
11
. A plurality of ZIF sockets
9
corresponding to ZIF connectors
11
are provided on the lower surface of the test head
10
. The semiconductor elements
6
exchange a test input signal and test output signals with the tester
3
, by means of the ZIF connectors
11
being coupled to the ZIF sockets
9
. The ZIF sockets
9
incorporate springs and are connected to the ZIF connectors
11
by means of meshing action.
As shown in
FIG. 14
, the probe card substrate
12
is attached to a probe card hold member
26
along with the reinforcement member
13
. As shown in
FIG. 15
, screws
17
are used for attaching the probe card substrate
12
and the reinforcement member
13
. As shown in
FIG. 15
, the wafer prober
2
is provided with the probe card hold member
26
, and the probe card hold member
26
is attached to a movable arm
27
. The probe card hold member
26
is used in transporting the probe card
1
into the wafer prober
2
or in transporting the probe card
1
outside the wafer prober
2
. The probe card hold member
26
is used for fixing the probe card
1
within the prober
2
. The probe card hold member
26
is formed into a ring, and the probe card substrate
12
of the probe card
1
is attached to the probe card hold member
26
with the reinforcement member
13
such that the probe needles
7
protrude from an opening of the ring-shaped probe card hold member
26
. As shown in
FIG. 16
, the probe card
1
is held so as to protrude from an opening
25
formed in an top of the prober
2
while being attached to the probe card hold member
26
. The probe card
1
is positioned by means of positioning pins
14
of the test head
10
. In this state, the probe card
1
opposes the semiconductor wafer
5
provided on top of the stage
4
with a predetermined space therebetween.
In the related-art apparatus using the screws
17
, when a test is performed, the stage
4
is elevated, thereby pressing the semiconductor wafer
5
against the probe needles
7
. At this time, stress concentrates at the portions of the probe card substrate
12
where the reinforcement member
13
is attached by means of the screws
17
, as a result of which load is imposed so as to induce warpage in the probe card
1
. Accordingly, warpage partially develops in the probe card substrate
12
. When the probe card
1
has been used over a long period of time, the tip ends of the probe needles
7
become offset from their initial locations. Uniform contact between the probe needles
7
and the semiconductor elements
6
is not sustained. As a result, contact failures arise in some of the semiconductor elements
6
, such that non-defective elements
6
may be determined to be defective.
In order to prevent occurrence of warpage in the probe card substrate
12
, which would otherwise arise while the probe card substrate
12
is in use, the reinforcement member
13
constituted of a flat plate of hard material is used, as shown in
FIG. 17. A
structure for attaching the reinforcement member
13
to the probe card substrate
12
and to the probe card hold member
26
is specifically shown in FIG.
18
. Counterbores
13
a
to be used for attaching the screws
17
are formed in two attachment arms
13
A and
13
C from among four attachment arms
13
A through
13
D of the reinforcement member
13
. In contrast, no counterbores
13
a
are formed in the remaining two attachment arms
13
B and
13
D. Thus, the attachment structure is not uniform. such a non-uniform attachment structure is ascribable to the positioning pins
14
of the test head
10
. In order to avoid the positioning pins
14
, the counterbores
13
a
are formed in only the attachment arms
13
A and
13
C. However, the attachment structure is not uniform and fails to sufficiently prevent occurrence of warpage in the probe card substrate
12
. Reference numeral
16
designates a through hole through which the attachment screws
17
penetrate.
The test head
10
is a housing in which a plurality of terminals are provided in a concentrated manner for connecting the tester
3
with the probe card
1
. As shown in
FIGS. 15 and 16
, the test head
10
is provided on top of the wafer prober
2
in a reclosable manner. The positioning pins
14
of the test head
10
are provided for enabling the test head
10
, the probe card
1
, and the wafer prober
2
to be connected together at the same positions at all times. Positioning holes
21
(see
FIG. 16
) formed in the probe card substrate
12
are located close to the edges of the attachment arms
13
A and
13
C. Hence, the counterbores
13
a
are formed in only the attachment arms
13
A and
13
C.
As shown in
FIG. 18
, because of such a non-uniform attachment structure, short screws
17
are used for the attachment arms
13
A and
13
C, and long screws
17
are used for the attachment arms
13
B and
13
D. The difference in length between the screws
17
also accounts for occurrence of warpage in the probe card substrate
12
. Use of two types of screws
17
having different lengths makes attachment and removal of the screws
17
complicated, thus resulting in consumption of excessive time.
When the probe needles
7
are brought into contact with the electrode pads
8
of the semiconductor element
6
under normal conditions, the st
Hollington Jermele
McDermott & Will & Emery
Pert Evan
Renesas Technology Corp.
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