JPH0145029B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a probe needle that is attached to a probe card and used when testing the characteristics of integrated circuits such as wafers.

Generally, a probe card is configured as follows. That is, as shown in FIGS. 1 and 2, the probe card 1 includes a substrate 2, a probe ring 3, and a number of probe needles 4 attached to the lower surface of the probe ring 3. Said substrate 2
A circuit (hereinafter referred to as a peripheral circuit) for testing the electrical characteristics of an integrated circuit or for supporting the test is incorporated in the
It has a ring-shaped fixing part 5 for fitting and fixing the probe ring 3 into its main body part, and has a connector 7 connected to a tester 6 at its base end. A socket portion 8 is formed in the fixing portion 5 and is electrically connected to a peripheral circuit. On the other hand, probe ring 3
The top surface has the same number of pin parts 9 as the probe needles 4.
is formed, and the pin portion 9 is electrically connected to the probe needle 4. Then, at the same time as the probe ring 3 is mechanically fitted to the fixed part 5, the pin part 9 is fitted to the socket part 8, thereby electrically connecting the peripheral circuit on the board 2 and the probe needle 4. . In such a case, the tester 6 is connected to the connector 7 of the board 2, and the probe needles 4 are brought into contact with each terminal of the integrated circuit 10 to be tested, thereby testing the characteristics of the integrated circuit 10.

By the way, the probe needle 4 has its main body 11.
It is required that the needle tip 12 of the stylus reliably contacts the terminal of the integrated circuit 10 under test. However, as shown in FIGS. 7A and 7B, in the conventional probe needle 4, the bottom surface 13 of the needle tip 12 that contacts the terminal is partially spherical (FIG. 7A) or circularly planar (FIG. 7A). (b), so in either case, it will come into point contact with the terminal surface, resulting in poor contact if the contact pressure is weak, or if the contact pressure is strong. In any case, it is impossible to completely avoid unstable contact conditions, such as damage such as pinholes on the terminal surface of the contact portion, and there is a problem in that it is difficult to obtain sufficient measurement accuracy.

The present invention was made to solve this problem, and by fundamentally improving the bottom shape of the tip of the probe needle body, the bottom surface can be brought into stable line contact with the terminal surface, thereby improving measurement accuracy. The purpose is to achieve this goal.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 3 shows the main part of the probe needle according to the present invention. The probe needle main body 11 is made of a material such as tungsten, palladium alloy, or beryllium copper. It has a bent shape. This main body 11 has its base end attached to the lower surface of the probe ring 4 and is electrically connected to the peripheral circuit on the substrate 2 of the probe card 1, as in the well-known configuration described above (first (See Figure and Figure 2).

In FIG. 4, the needle tip portion 12 of the probe needle body 11 is formed in a tapered shape, and its front and rear surfaces 1
4 and 14 are formed into inclined planar cut sections. Now, the bottom surface 13 of this needle tip portion 12 is formed into a curved surface consisting of a partially cylindrical peripheral surface, and the diameter of the curved surface is set to an extent not exceeding approximately 0.5 mm.

In such a case, as shown in FIGS. 5 and 6, the needle tip 12 may be attached to the integrated circuit 10 at a certain angle.
The curved bottom surface 13 is placed in line contact with the surface of the terminal 15, and its bottom surface 13 comes into contact with the surface of the terminal 15, as is clear from both figures above. A predetermined contact pressure is stably applied onto the terminal 15.

Note that the bottom surface 13 of this needle tip portion 12 is
When considering variations in the contact angle between the terminal 15 and the terminal 15, and deviations of the needle tip 12 on the surface of the terminal 15, forming a curved surface made of the peripheral surface of a perfect cylinder will stabilize the contact pressure. Although desirable for retention purposes, it is also possible to form a curved surface included in the category of a partially cylindrical peripheral surface, such as the peripheral surface of a column having an elliptical cylinder or a parabolic cross section. Further, the cross-sectional shape of the probe needle main body 11 may be not only circular but also rectangular or the like.

As explained above, according to the present invention, the bottom surface of the tip of the probe needle body is formed into a curved surface having a partial cylindrical circumferential surface shape, so that the curved bottom surface of the needle tip can accumulate the test object such as a wafer. It was designed to make a line contact on a minute terminal of the circuit. Therefore, the contact pressure between the probe needle and the terminal is applied evenly to the surface of the terminal, so that stability can be achieved regardless of the strength of the contact pressure. Therefore, if an oxide film or the like is naturally formed on the terminal surface, the oxide film can be easily removed by applying strong contact pressure and sliding the bottom of the needle tip over the terminal surface. As a result, the cleaning effect stabilizes the contact resistance between the probe needle and the terminal at an appropriate value, contributing to improved measurement accuracy, and eliminating the risk of pinholes or other damage to the terminal itself. This makes it possible to reduce the incidence of defective products as much as possible during characteristic tests of the device under test, thereby improving the yield of the device under test. It is highly effective when applied to the measurement of characteristics.

[Brief explanation of drawings]

1 and 2 show a well-known probe card, with FIG. 1 being a plan view and FIG. 2 being a sectional view taken along the - line in FIG. 1. Figures 3 to 6 show embodiments of the present invention, with Figure 3 being a side view of the main part, Figure 4 being an enlarged perspective view of the needle tip, and Figure 5 being an enlarged front view of the main part showing the state of use. 6 is a view taken along the arrows in FIG. 5. FIGS. 7A and 7B are perspective views of needle tips showing different conventional examples. DESCRIPTION OF SYMBOLS 1... Probe card, 4... Probe needle, 10... Integrated circuit, 11... Probe needle body, 12... Needle tip of probe needle body, 13... Bottom surface of needle tip, 15... Integrated circuit terminal.

Claims (1)

[Claims] 1. In a probe needle that is installed in a probe card used for characteristic testing of integrated circuits, and is configured such that the bottom surface of the needle tip of the probe needle body comes into contact with the terminal of the integrated circuit during use, the probe needle body A probe needle characterized in that the bottom surface of the needle tip portion is formed into a curved surface in the shape of a partially cylindrical peripheral surface.