Semiconductor testing apparatus for conducting conduction tests

Details Semiconductor testing apparatus for conducting conduction tests Semiconductor testing apparatus for conducting conduction tests

2003-01-03

2004-07-20

Nguyen, Vinh P. (Department: 2829)

Electricity: measuring and testing

Fault detecting in electric circuits and of electric components

Of individual circuit component or element

C324S765010

Reexamination Certificate

active

06765401

ABSTRACT:

CROSS-REFERENCED TO RELATED APPLICATIONS
This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2002-153791, filed on May 28, 2002, the entire contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor testing apparatus for conducting a probing test on a semiconductor device or a substrate.
To effectively test a plurality of circuits formed on a semiconductor wafer, a probing card has 600 to 800 probing pins. Some of the probing cards manufactured presently have more than 1000 probing pins, adjacent ones of which have a spacing of 40 micrometers or less therebetween.
Since an electronic product, such as a cellular phone or a vehicle-mounted element, is used within a relatively wide temperature range, a circuit employed in such an electronic product is also tested over a wide range of temperatures. In a probing test, it is necessary to bring the probing pins into contact with the circuits substantially uniformly independently of a testing temperature.
Generally, in the step of manufacturing a semiconductor device, a probing test is conducted to test the conduction of a wafer. In the probing test, a plurality of probing pins are brought into contact with a plurality of corresponding pads formed on the wafer at a predetermined pressure. The various characteristics of the semiconductor device are measured in accordance with a probing test program.
The probing pins each elongate at a high test temperature and are shortened at a low test temperature. Accordingly, a pressure of contact between the pad and the probing pin varies, thus making the probing test unstable conventionally. The following will describe a conventional testing method by which an influence of a temperature variation in length of the probing pins is reduced.
FIG. 1
is a flowchart of a conventional probing test.
FIG. 2
shows a conventional semiconductor testing apparatus
100
. The semiconductor testing apparatus
100
includes a chuck
90
on which a wafer W is placed, a probing card
91
having probing pins
92
, and a heater
93
for heating the wafer W.
When the probing test starts, the semiconductor testing apparatus
100
holds the chuck
90
at a predetermined testing temperature after heating with the heater
93
in step S
91
. In step S
92
, the semiconductor testing apparatus
100
moves the chuck
90
to a position which is separate downward from the probing card
91
by a predetermined spacing, for example, 500 micrometer. The chuck
90
radiates heat to pre-heat the probing pins
92
. The pre-heating time ranges from a few minutes to several tens of minutes corresponding to the size of the probing card
91
.
In step S
93
, the semiconductor testing apparatus
100
monitors the tip of the probing pin
92
and the upper surface of the wafer W using a camera (not shown) to simultaneously calculate the height of the chuck
90
when the tip of the probing pin
92
is brought into contact with the upper face of the wafer W.
In step S
94
, the semiconductor testing apparatus
100
moves the chuck
90
to the height thus calculated and brings the tip of the probing pin
92
into contact with the wafer W and then conducts a conduction test.
It is to be noted that since in the conventional semiconductor testing apparatus
100
, the probing pin
92
is pre-heated indirectly in the position which is separate from the chuck
90
, its temperature is saturated before the probing pin
92
reaches the testing temperature. The temperature of the probing pin
92
, therefore, is lower than the testing temperature, or the temperature of the wafer W.
FIG. 3
is a graph for showing the relationship between the pre-heating time and the height of the tip of the probing pin
92
. The height of the tip of the probing pin
92
was measured along the z-axis of
FIG. 2
in a condition where the probing card
91
is fixed. As the pre-heating time is prolonged, the probing pin
92
is elongated by heating, resulting in a decrease in the height of the tip thereof. At a time T11, the probing pin
92
has temperature saturation and so stops elongating, thus causing the height of the tip also to stop decreasing. From the time T11 on, the tip is kept at a substantially constant height. A fluctuation &Dgr;H in the height of the tip owing to pre-heating is about a few tens of micrometers.
During the conduction test, the probing pin
92
is in contact with the wafer W, so that the probing pin
92
is heated by the wafer W to the testing temperature. Therefore, the probing pin
92
elongates further, thus decreasing the height of the tip thereof. Accordingly, a pressure of contact between the probing pin
92
and the wafer W varies greatly during the conduction test (step S
95
).
In the case of cooling the wafer W down to the testing temperature in order to conduct a probing test, on the other hand, a cooling circuit is used instead of the heater
93
. In this case, the probing pin
92
is pre-cooled above the chuck
90
and so shrinks, thus increasing the height of the tip thereof. Furthermore, indirect pre-cooling causes the temperature of the probing pin
92
to become higher than that of the wafer W.
FIG. 4
is an illustration for showing a pin trace formed by contact between the probing pin
92
and the wafer W.
At the middle row in
FIG. 4
is shown a pin trace formed in the test at the normal temperature. In this case, the pin trace stayed substantially in a constant position at a time immediately after contact of the probing pin
92
with the wafer W, at a time ten minutes after contact, and at a time of contact in the next position. This is because the temperatures of the probing pin
92
and the wafer W do not vary even when they come in contact with each other.
At the upper row in
FIG. 4
, on the other hand, is shown a pin trace in the test at a high temperature. In this case, although immediately after contact, the pin trace has a shift in position corresponding to the elongation of the tip of the probing pin
92
owing to pre-heating, the pin trace geometry stays the same as that at the normal temperature. However, as the probing pin
92
is heated by contact with the wafer W to the testing temperature, the probing pin
92
elongates, so that the pin trace expands and becomes large.
At the lower row in
FIG. 4
is shown a pin trace formed in the test at a low temperature. In this case, although immediately after contact, the pin trace has a shift in position corresponding to the shortening of the tip of the probing pin
92
owing to pre-cooling, the pin trace geometry stays the same as that at the normal temperature. However, as the probing pin
92
is cooled by contact with the wafer W down to the testing temperature, the probing pin
92
shortens, so that the pin trace is shortened and small.
In the conventional semiconductor testing apparatus
100
, therefore, the pressure of contact between the probing pin
92
and the wafer W is unstable, thus likely to give rise to poor contact.
In a conduction test, the probing pin
92
is brought into contact with an electrode (pad) formed on the wafer W. If slippage (scrubbing quantity) of the probing pin
92
is large, the pin trace goes out of the relatively small electrode into a bonding region, thus deteriorating the strength thereof.
Japanese Laid-open Patent Publication No. Hei 5-152389 discloses a probing card and a test bench which have a heating body (or cooling body) buried therein. The heating body (or cooling body) causes the probing card (probing pin) and the test bench to have the same temperature. Accordingly, a fluctuation of a probing pin temperature owing to contact between the probing pin and the wafer is suppressed to suppress the elongation of the probing pin. It is necessary, however, to provide the heating body (or cooling body) for each probing card, so that costs are increased for testing and the manufacture of the semiconductor testing apparatus. Furthermore, the heating body in the probing card is electrified, so that test res

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