Probe card for testing an integrated circuit

Details Probe card for testing an integrated circuit Probe card for testing an integrated circuit

2002-06-13

2004-10-26

Tang, Minh N. (Department: 2829)

Electricity: measuring and testing

Fault detecting in electric circuits and of electric components

Of individual circuit component or element

C324S754090, C324S761010

Reexamination Certificate

active

06809539

ABSTRACT:

This patent application claims priority based on a Japanese patent application, 2000-145975 filed on May 18, 2000, the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a probe card allowing signals to be transmitted between an integrated circuit and semiconductor testing equipment, especially to a probe card which can transmit high frequency signals to an integrated circuit having a plurality of pads on a narrow pitch area.
2. Description of the Related Art
When an integrated circuit is manufactured, testing the electric characteristic of the integrated circuit must be performed during manufacture. In order to perform this test, the installation of a transmission path for a test signal to be transmitted between a wafer where the integrated circuit is manufactured and semiconductor testing equipment is required. The transmission path may include a contactor on its front-end portion, and the test signal generated by the semiconductor testing equipment is provided to the integrated circuit by contacting the contactor to a contact terminal of the integrated circuit. Recently, as semiconductor devices operating at high frequency have been rapidly developed, the semiconductor testing equipment, the contactor and the transmission path between the semiconductor testing equipment and the contactor have been required to be ready for high frequency operation. Moreover, as density degree (or degree of integration) of recent semiconductor devices has increased remarkably, it has been required to develop a transmission path through which test signals can be provided to an integrated circuit having a plurality of pads on a narrow pitch area.
FIG. 1
shows a schematic diagram of a conventional contacting unit
10
through which a high frequency test signal can be transmitted between semiconductor testing equipment and a circuit under test, which is being tested. The contacting unit
10
includes a contactor
12
, a coaxial cable
14
and a support-and-fixing unit
16
. The contactor
12
clings to a front-end portion of the coaxial cable
14
, and, during a test, is contacted to a contact terminal (for example, a pad, a soldering ball, a gold bump) of the circuit under test. The coaxial cable
14
is connected to the external semiconductor testing equipment (not shown). The support-and-fixing unit
16
supports the coaxial cable
14
and fixes the position of the contactor
12
.
The transmission of signals between the external semiconductor testing equipment and the circuit under test is performed through the coaxial cable
14
. Therefore, when a high frequency signal is transmitted by using the contacting unit
10
, attenuation of the transmitted signal can be greatly reduced.
FIG. 2
shows a diagram of a portion of the contacting unit
10
near the contactor
12
in the direction of arrow A of FIG.
1
. As shown in
FIG. 2
, the coaxial cable
14
has a signal line
18
a
for transmitting signals and a grounding line
18
b
for grounding. The contactor
12
includes a contactor
12
a
connected to a signal line of the circuit under test and contactors
12
b
and
12
c
connected to a grounding unit of the circuit under test. The contactors
12
a
,
12
b
and
12
c
are formed to be “air-coplanar” and maintain an impedance matching state almost until its front-end.
FIG. 3
shows the contactor
12
contacted to the circuit under test. The contactor
12
a
is contacted to the signal line
20
a
of the circuit under test, and contactors
12
b
and
12
c
are contacted to the grounding unit
20
b
and
20
c
of the circuit under test. The contacting unit
10
having the coaxial cable
14
can transmit high frequency signals of more than 100 GHz. Recent development of the integrated circuit is intended not only to increase speed operation but also to increase minuteness and increase integration of the circuit. According to the contacting unit
10
shown in
FIG. 1
, since the pitch of the contactor
12
is limited by the diameter of the coaxial cable
14
, it is impossible to perform a test on a highly integrated circuit having pads of narrow pitches. Further, as the integration degree of the circuit is increased, since the number of pads formed on the circuit is more than several thousand, it is unreasonable in the cost aspect to form the contacting unit
10
shown in
FIG. 1
as many as the number of the pads. Further, operating frequency of the next generation integrated circuit is in the range of 1 to several Giga-Hertz (GHz) and the contacting unit
10
is able to transmit high frequency signals of more than 100 GHz frequency band, but at present, it is not required to transmit such high frequency signals of more than 100 GHz frequency band.
Besides the contacting unit
10
shown in
FIG. 1
, a probe card having a plurality of contactors on a narrow pitch area is conventionally used for testing a circuit having a plurality of pads on a narrow pitch area. This probe card is required to be faster and have more pins on a narrower pitch. Further, the probe card is also required to have fine positioning ability and scrub function to perform sliding operation against pads of the circuit under test, to be light in weight for preventing deformation of the probe card and the wafer due to the weight, and to have area-array adaptability to a circuit of full-face terminal type. Further, in order to prevent waveform distortion during a test, a characteristic impedance from the input/output terminal of the semiconductor testing equipment and the contact terminal (pad) of the circuit under test must be maintained to be a predetermined value. Hereinafter, four (4) kinds of conventional probe pins used for the probe card are described in detail, and weak points of them are also described.
FIG. 4
shows conventional probe pins of a horizontal needle probe type. According to the horizontal needle probe type, a needle of diameter 200~300 um is used, wherein the needle is made of a metal like W, ReW, BeCu or Pd and has a tapered end. According to the conventional type, since the end of the needle is as long as 20 mm, the characteristic impedance is changed on the end area and reflection noise is generated. Therefore, measurable maximum frequency is as low as 0.2 GHz. Further, since this type of probe pin is made by hand, it is difficult to accomplish area-array adaptability, high density, low weight and fine positioning ability. Moreover, since the needle made of W, ReW, BeCu or Pd has crystalline grains, scrapes generated through scrubbing with the pad enter into the crystalline grains of the needle made of this kind of material after repeated contact with the pad of the circuit under test, and, as a result, contact resistance is increased.
FIG. 5
shows another conventional probe pin of a vertical needle probe type. The vertical needle probe type is developed to achieve the area-array adaptability and high density, which were problematic of the horizontal needle probe type, but the achievement level is still unsatisfactory. Further, compared with the horizontal type, the vertical needle probe type is at least 1.5 times heavier in weight, and it is impossible to achieve the goal of being light weight. According to the structure of the vertical type, since it is difficult to perform sliding operation, it is impossible to achieve satisfactory scrub function.
FIG. 6
shows conventional probe pins made by the membrane method. The membrane method is developed to accomplish goals of high speed, high density and area-array adaptability. According to the membrane method, metal bumps as probe pins are formed on the wiring substrate of polyimide film. The height of a metal bump is as low as dozens of micrometers (um), and it is possible to form a transmission path just in front of the metal bump, so that it is possible to achieve high speed operation. According to this method, however, since load is applied in the vertical direction, it is difficult to achieve a powerful scrub function. Further, since polyimide film is used as

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