JP2001159641A - Semiconductor process evaluating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor process evaluating device that can accurately evaluate a device with desired current density. SOLUTION: In the semiconductor process evaluating device for carrying out a conduction test by applying a probe needle on a wafer, a heat sink is formed in the probe needle, in partially scraped so that the tip of the probe needle can be viewed from an upper surface, is set to a radial shape, and at the same time is composed by one or a plurality of metal materials or materials with an excellent heat radiation property.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a semiconductor process evaluation apparatus for conducting a current test by applying a probe needle to a wafer.

[0002]

2. Description of the Related Art A probing test is one method of evaluating semiconductor processes. This is to evaluate the quality of the wafer by inspecting the intensity of emitted light by conducting a current test by applying a needle (probe needle) to the electrode pad while the wafer is in the middle inspection of the process of manufacturing a semiconductor device. is there. Probing tests are done frequently today,
Hereinafter, a semiconductor process evaluation apparatus refers to an apparatus that performs this probing test.

FIG. 11 is an explanatory view of a conventional semiconductor process evaluation apparatus. 21 is a probe needle. A current test is performed by applying a probe needle 21 to the electrode pad as it is on the wafer to check the intensity of light emitted from the wafer portion where the current is injected. As the probe needle 21, one formed of tungsten, a beryllium alloy, or the like is often used.

[0004]

The conventional semiconductor process evaluation apparatus has the following problems.

In the probing test, the current flows in the order of the tip (tip) of the probe needle 21, the electrode pad, and the wafer, and the wafer portion into which the current is injected emits light. here,
There are many types of devices, such as bipolar transistors, power FETs (field effect transistors), LE
D (light emitting diode), LD (laser diode), etc., and the heat radiation state of the heat generated in the blowing test on the wafer differs depending on the type of device. Depending on a certain device, there is a problem that the temperature rises during a probing test due to a significant difference between the actual device and the wafer state, and accurate evaluation cannot be performed. In some cases, the wafer was broken during the probing test. In this case, the number of items that cannot be evaluated increases if the injected current density is lowered so that the wafer is not broken.

In some devices, the probe needle 21
In some cases, heat generation due to contact resistance between the electrode and the electrode pad must be taken into consideration. In that case, there is a problem that a probing test is not easy and accurate evaluation is difficult.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned disadvantages of the prior art and to provide a semiconductor process evaluation apparatus capable of performing accurate device evaluation at a desired current density.

[0008]

According to the present invention, in order to achieve the above object, a heat sink is formed on the probe needle in a semiconductor process evaluation apparatus in which a probe needle is applied to a wafer to conduct an electric current test. The radiator plate was configured so that a part thereof was scraped off so that the tip of the probe needle could be viewed from above.

The radiator plate has a radial shape and is made of one or more metals or a material having good heat dissipation.

[0010]

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

FIG. 1 is a sectional view showing a first embodiment of a semiconductor process evaluation apparatus according to the present invention. FIG. 2 is a front view of the probe needle of FIG. 1, and FIG. 3 is a plan view of the probe needle of FIG. 1 is a semi-insulating GaAs substrate, 2 is a collector layer,
3 is a base layer, 4 is an emitter layer, and 5 is a probe needle.

The device under the probing test is a hetero bipolar transistor (HBT). This device has n on a semi-insulating GaAs substrate 1.
-GaAs layer (collector layer) 2, p-GaAs layer (base layer) 3, and n-AlGaAs layer (emitter layer) 4
It is formed by an E method, and an electrode pad is formed by a photolithography process, a vapor deposition, and a lift-off process. The size of the electrode pad is 20 μm × 20 μm for the n-AlGaAs layer (emitter layer) 4, 100 μm × 100 μm for the p-GaAs layer (base layer) 3, and 100 μm × 100 μm for the n-GaAs layer (collector layer) 2. .

The probe needle 5 is provided with a heat radiating plate for cooling the probe needle 5 as shown in FIGS. The radiator plate is configured so that a part thereof is scraped off so that the tip of the probe needle can be seen from the upper surface. The heat radiating plate has a radial shape and is made of one or a plurality of metals or a material having good heat radiating properties. As the metal, tungsten or a beryllium alloy was used.

While the HBT was in a wafer state, a current test was performed on a stage of Au plating with a conventional probe needle and the probe needle shown in FIG. 2, and a Gummel plot was measured. FIG.
Is a Gummel plot measurement diagram. As a result, the conventional probe needle shows current-voltage characteristics (IV characteristics) like Ic-A and Ib-A shown in FIG. 4, and the probe needle shown in FIG. 2 shows Ic-B and Ib-B. It exhibited excellent current-voltage characteristics (IV characteristics). It was found that when this difference in the characteristic values was converted into the bonding temperature, it was equivalent to about 100 ° C. That is, it was possible to measure up to a higher current region.

In the first embodiment of the semiconductor process evaluation apparatus of the present invention, natural cooling of the probe needle by the heat radiating plate is sufficient. However, in a device having another increased number of emitter fingers, natural cooling alone is not sufficient. Was enough. Therefore, the gas pipe is led to the heat sink of the probe needle of the present invention, and air,
By spraying nitrogen gas, the cooling efficiency could be further improved, and measurement was possible up to a higher current region.

FIG. 5 is a sectional view showing a second embodiment of the semiconductor process evaluation apparatus of the present invention. 11 is semi-insulating Ga
As substrate, 12 is an n-type semiconductor layer, 13 is a p-type semiconductor layer,
14 is a probe needle. The shape of the probe needle is the same as that of the first embodiment of the semiconductor process evaluation apparatus of the present invention.

The device under probing test is a planar diode. This device comprises an n-type semiconductor layer 12, a p-type semiconductor layer 12 on a semi-insulating GaAs substrate 1.
Forming a semiconductor layer 13 by MBE, a photolithography process,
An electrode pad is formed by a vapor deposition and lift-off process. The size of the electrode pad is 100 μm × 100 μm for the n-type semiconductor layer 12 and 12 μm for the p-type
It is 0 μm × 120 μm. As in the first embodiment of the semiconductor process evaluation apparatus of the present invention, measurement was possible up to a high current region.

FIGS. 6 to 10 are plan views showing another first to fifth embodiments of the probe needle according to the semiconductor process evaluation apparatus of the present invention. The shape of the heat radiating plate is characteristic, and each heat radiating plate is configured so that a part thereof is cut off so that the tip of the probe needle can be visually observed from the upper surface. Each of the heat radiating plates has a radial shape, and is made of one or a plurality of metals or a material having good heat radiating properties. Metals such as tungsten and beryllium alloy were used.

Since the shape of the heat radiating plate is different from each other, the heat radiating characteristics are different, and the heat radiating plate can be used properly depending on the device for performing the probing test. With any of the probe needles, the wafer can be evaluated at a desired current density or a high current region, and accurate device evaluation has become possible.

[0020]

The semiconductor process evaluation apparatus according to the present invention is a semiconductor process evaluation apparatus for performing an electrical test by applying a probe needle to a wafer, wherein a heat sink is formed on the probe needle, and the heat sink is partially formed. Since the tip of the probe needle is cut off so that the tip of the probe needle can be seen from the upper surface, and the shape of the heat radiating plate is radial, and one or more sheets of metal or a material having good heat radiating property are used. Thus, accurate device evaluation can be performed at a desired current density.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of a semiconductor process evaluation apparatus of the present invention.

FIG. 2 is a front view of the probe needle of FIG.

FIG. 3 is a plan view of the probe needle of FIG. 1;

FIG. 4 is a Gummel plot diagram according to the first embodiment of the semiconductor process evaluation apparatus of the present invention.

FIG. 5 is a sectional view showing a second embodiment of the semiconductor process evaluation apparatus of the present invention.

FIG. 6 is a plan view showing another first embodiment of the probe needle according to the semiconductor process evaluation apparatus of the present invention.

FIG. 7 is a plan view showing another second embodiment of the probe needle according to the semiconductor process evaluation apparatus of the present invention.

FIG. 8 is a plan view showing another third embodiment of the probe needle according to the semiconductor process evaluation apparatus of the present invention.

FIG. 9 is a plan view showing another fourth embodiment of the probe needle according to the semiconductor process evaluation apparatus of the present invention.

FIG. 10 relates to a semiconductor process evaluation apparatus of the present invention;
It is a top view showing other 5th examples of a probe needle.

FIG. 11 is an explanatory diagram of a conventional semiconductor process evaluation apparatus.

[Explanation of symbols]

 Reference Signs List 1 semi-insulating GaAs substrate 2 collector layer 3 base layer 4 emitter layer 5 probe needle 11 semi-insulating GaAs substrate 12 n-type semiconductor layer 13 p-type semiconductor layer 14 probe needle 21 probe needle

Claims (3)

[Claims] 1. A semiconductor process evaluation apparatus for conducting an electric current test by applying a probe needle to a wafer, wherein a heat radiation plate is formed on the probe needle. 2. The semiconductor process evaluation apparatus according to claim 1, wherein the heat radiating plate is partially cut away so that the tip of the probe needle can be seen from the upper surface. 3. The semiconductor process evaluation according to claim 1, wherein the heat radiating plate has a radial shape and is made of one or more metal or a material having good heat radiating property. apparatus.