JPH0669054B2 - Probe needle for measuring electrical characteristics of semiconductor wafers - Google Patents

Description

TECHNICAL FIELD The present invention relates to a probe needle for measuring a parameter of a pad such as IC or LSI on a wafer.

(Prior Art) Conventionally, as a probe needle capable of measuring an electrical characteristic even in a high frequency region when measuring an electrical characteristic of a pad 2 such as an IC or LSI on a wafer 1 shown in FIG. As shown in the figure, the coaxial cable 3 is formed by projecting a signal line 4 at the center of the tip of the coaxial cable 3, attaching a ground portion 5 to the outer circumference of the tip of the coaxial cable 3, and bringing its tip close to the tip of the signal line 4 by about 200 μ. Set the needle 6 to X of the measuring instrument 7 as shown in FIG.
A method of setting the arm 8 movable in the Y and Z axis directions and bringing it into contact with a pad 2 such as an IC or LSI on the wafer 1 to measure electrical characteristics is adopted.

(Problems to be Solved by the Invention) By the way, in the above coaxial probe needle 6, since the signal line 4 and the ground portion 5 do not form a coaxial structure over a few mm at the tip of the coaxial cable 3, the characteristic impedance is limited to that portion. However, the electrical characteristics could not be accurately measured in the high frequency range. In addition, it was impossible to realize multiple terminals with this structure.

On the other hand, the development of high-density and high-speed ICs and LSIs has recently been advanced, and as a prober for evaluating these, stable characteristic impedance, multiple terminals, and reliable contact with pads on the wafer It is necessary to provide a probe needle that can achieve this, and the development of this is urgent.

Therefore, the present invention is intended to provide a probe needle that can achieve stabilization with respect to setting of characteristic impedance, increase in number of terminals, and reliable contact, and that can accurately measure electrical characteristics in a high frequency region.

(Means for Solving Problems) According to the present invention for solving the above problems, a plurality of columns of transmission lines are provided in parallel on a dielectric substrate, and the tip of each transmission line is isolated from the dielectric substrate. The electrically insulating elastic body is filled under the raised portion.

(Examples) Various examples of the probe needle of the present invention will be described with reference to the drawings.

The probe needle 27 shown in FIG. 1 is made of alumina (Al ₂ O ₃ ) and has a length of 40 mm, a width of 10 mm, and a thickness of 0.6 mm, and is made of Cu having a thickness of 3 μ and a width of 150 μ in the longitudinal direction. Transmission line 12
Are installed in parallel in three rows with a spacing of 200μ, and each transmission line 12
80 μm in height in the shape of a trapezoid on the side of the
The upper surface 14 of the is a contact surface with a length of 100μ and a width of 150μ
An electrically insulating elastic body 28 made of photosensitive polyimide is filled in a space below the space 13.

The probe needle 29 shown in FIG. 2 has the same dielectric substrate 11 as that shown in FIG.
The height of the tip of each transmission line 12 is set to be 80μ
The tip of the raised part (17) is bent downward at a right angle and is joined to the leading end surface (18) of the dielectric substrate (11), and the upper surface (18) of the raised part (17) forms a contact surface having a length of 110 μ and a width of 150 μ.
The space below the space is filled with an electrically insulating elastic body 28 made of photosensitive polyimide.

The probe needle 30 shown in FIG. 3 is the probe needle shown in FIG.
The tip junction of the side trapezoidal ridge 13 formed at the tip of each transmission line 12 in 10 is bent upward and downward to join the tip surface 18 of the dielectric substrate 11 and below the ridge 13. The side is filled with an electrically insulating elastic body 28 made of photosensitive polyimide.

In the probe needle 31 shown in FIG. 4, the tips of the transmission lines 12 provided in parallel in three rows on the dielectric substrate 11 are raised by 80 μ in height,
The leading edge 23 is floated by 80 μ, and the space below the ridge 23 is filled with an electrically insulating elastic body 28 made of photosensitive polyimide.

The probe needle 32 shown in FIG. 5 corresponds to the probe needle 21 shown in FIG.
At the leading edge 23 of each transmission line 12 in
Is provided, and the space on the lower side is filled with an electrically insulating elastic body 28 made of photosensitive polyimide.

The probe needle 33 shown in FIG. 6 corresponds to the probe needle 31 shown in FIG.
The raised portion 23 is formed in a comb shape so as to make a multipoint contact.

It should be noted that the electrically insulating elastic body 28 filled below the ridge of each transmission line in the probe needle shown in FIGS.
May be a continuous, one-piece, electrically insulating elastic body in a direction orthogonal to the transmission line. Further, although the dielectric substrate in the probe needles of FIGS. 1 to 6 is made of alumina, it may be made of quartz. In addition, the transmission line
Although 12 has 3 rows, it is not limited to this and any number of rows from 2 to may be used. The transmission line 12 is made of Cu, but the Cu surface may be plated with Au.

As can be seen in the above embodiments, the probe needle of the present invention, the transmission line 12 is provided in parallel in a plurality of columns on the dielectric substrate 11, the transmission line 12 has a strip line structure,
The characteristic impedance of the transmission line 12 is constant in any part. Therefore, the probe needle of the present invention is, for example, the probe needle 27 shown in FIG. 1 and the X of the measuring instrument 7 as shown in FIG.
The electric characteristics were measured by setting the arm 8 movable in the Y and Z axis directions and contacting the pad 2 such as IC and LSI on the wafer 1, and in the high frequency region, in this example, a high frequency of 30 GHz was used. The electrical characteristics could be measured accurately at the frequency.

Further, in the probe needle of each example, the tip end of each transmission line 12 is isolated from the dielectric substrate 11 and raised, the upper surface of this raised portion is used as a contact surface, and an electrically insulating elastic body is provided below the raised portion. Since the ridges are filled so as to be elastically deformable, the IC and LS on the wafer to be measured in the electrical characteristic measurement
When contacting the pad 2 such as I, the contact portion of each transmission line 12 is not crushed, and always makes stable contact. Furthermore, in the probe needles of FIGS. 2, 3, and 5 in which the tips of the ridges of the transmission line 12 project from the tip surface of the dielectric substrate 11, the wafer is observed with a microscope when measuring the electrical characteristics. 1
When aligning with the pad 2 of the above IC, LSI, etc., since the contact portion is visible outside the dielectric substrate 11, the alignment can be performed easily and the measurement work can be performed efficiently (effect of the invention). As can be seen, the probe needle of the present invention has the transmission lines provided in parallel in a plurality of columns on the dielectric substrate, so that the transmission lines have a strip line structure. Therefore, multiple terminals can be realized by the transmission lines in a plurality of rows.
Moreover, in the probe needle of the present invention, the tip ends of the plurality of transmission lines are separated from the dielectric substrate and raised, and the raised portions are used as contact portions to fill the electrically insulating elastic body under the raised portions to raise the raised portions. Since it is elastically deformable, the contact portion of each transmission line is not crushed when it comes into contact with the object to be measured, and all of them are always reliably and stably contacted. Thus, it is possible to accurately, reliably, and stably measure the electrical characteristics of the pads of ICs, LSIs, etc. on the wafer, which have a high density and a high speed, in the high frequency region.

[Brief description of drawings]

1 to 6 are perspective views showing an embodiment of a probe needle for measuring electrical characteristics of a wafer according to the present invention, respectively. FIG. 7 is a schematic view showing a usage state of the probe needle shown in FIG. 1, and FIG.
FIG. 9 is a perspective view of a conventional coaxial probe needle, and FIG.
It is the schematic which shows the use condition of the coaxial probe needle of the figure.

Claims (1)

[Claims] 1. A transmission line is provided in parallel in a plurality of columns on a dielectric substrate, the tip of each transmission line is raised so as to be isolated from the dielectric substrate, and an electrically insulating elastic body is provided below the raised portion. A probe needle for measuring electrical characteristics of a semiconductor wafer, which is filled.