JPS62190737A - Low temperature auto-prober - Google Patents

Abstract

PURPOSE:To perform a probe test at cryogenic temperature by positioning a probe by a low temperature auto-prober which emits infrared light of long wavelength band. CONSTITUTION:Since exciting energy of visible light is not generated even by emitting infrared light of long wavelength of 1.2mum or longer, when a probe test is executed in the infrared light of long wavelength band of 1mum or longer, low temperature characteristics are obtained correctly in the same manner as a black box. A housing 20 is enclosed by a heat insulator, a movable stage 12 for placing a wafer 11 is formed of a cryostat head, the housing 20 is evacuated in vacuum, and helium gas is fed from the other. Infrared light of 1.2mum of wavelength is emitted from an infrared light source 14 to the wafer 11 through a transmission window 16, and a probe card 13 is positioned while observing in a microscope 15. Thus, it can be finely adjusted by a manipulator, readily automatically fed to perform a prove test by the auto-prober.

Description

[Detailed Description of the Invention] [Summary] An autoprober for low temperature measurement irradiates infrared rays in a long wavelength range of 1 μm or more, and adjusts the positioning of the probe while visually observing the irradiated light. In this way, measured values can be obtained at low temperatures without the influence of light irradiation.

[Industrial application field] The present invention relates to an autoprober for low temperatures.

Recently, high-speed operation elements have been required for semiconductor devices due to the demands of computers, etc., and new elements are being developed that actively consider not only operation at room temperature but also operation at low temperatures. For example, high electron mobility transistor (HE MT! H
igh Electron Mobility Tr.

) is an example.

Semiconductor devices that operate at such low temperatures naturally undergo probe tests (probe tests) in wafer form at low temperatures.
It is desirable to do this.

[Prior Art] Conventionally, in semiconductor devices such as ICs, a large number of elements are formed on a wafer, and before the wafer is divided into individual chips, a probe is brought into contact with the wafer to detect the electricity of those elements. This is called a wafer probe test, and the measuring device is called a prober.

This is because if a probe test is performed in advance on a wafer, defective chips can be assembled into a package and packaging materials can be saved. Figure 3 shows an outline of a prober test head at normal room temperature. 1 is Unibar, 2 is a movable stage, 3 is a probe, 4 is a visible light source,
5 is a microscope.

Semiconductor elements are regularly arranged on the wafer to be measured, and if the probe is positioned correctly using visible light and visually inspected with a microscope at the beginning of the measurement, the movable stage 2 will move automatically from then on. It can measure semiconductor devices on a wafer one after another, and is therefore called an autoprober.

In addition to the above test head, the autoprober is equipped with a computer, and the test head shown in Fig. 3 is equipped with a box 1.
0 (indicated by a broken line), visible light is irradiated from a cavity provided in the upper center of the probe, and the probe is aligned by moving a manipulator while visually observing it with a microscope. Furthermore, recently, in order to avoid the complexity of individually adjusting a plurality of probes, a probe card on which already aligned probes are planted is often used.

However, this probe card also needs to be aligned with respect to the semiconductor element.

[Problems to be Solved by the Invention] Incidentally, it is difficult to finely adjust the position of such a probe unless it is irradiated with visible light. Therefore, conventionally, in semiconductor devices operated at room temperature, alignment has been performed by irradiating visible light from a tungsten lamp or the like.

However, when semiconductor devices operated at low temperatures, such as 77°, are probe tested at the same temperature, excitation energy from visible light is generated, which accumulates in the semiconductor devices on the wafer, causing remain (remember),
There is a problem that the operating state cannot be measured correctly. This memory operation is thought to occur because free electrons are taken into the interface trap level under the influence of optical energy phonons, and charges are accumulated there.

Therefore, when trying to measure low-temperature operation, it is not possible to align the position by irradiating visible light, so conventionally, low-temperature operation elements are assembled in a black box (dark box).
The method used is to cool the black box to a low temperature and measure its operating characteristics. That is, the current situation is that an autoprober is not used.

However, in this way, instead of a probe test,
Measuring assembled semiconductor devices has the drawbacks of being very time-consuming and expensive.

The present invention solves these drawbacks and proposes a low-temperature autoprober that is capable of performing probe tests at low temperatures.

[Means for solving the problem] The purpose is to use a wavelength of 1 μm for positioning the probe.
This is achieved by a low-temperature auto blower that irradiates infrared light in the above long wavelength range.

[Function] That is, the present invention irradiates infrared rays in a long wavelength band of 1 μm or more to align the probe using infrared light. In this way, you can perform a probe test to determine the effects of the irradiation light.

[Example] A detailed description will be given below with reference to the drawings.

FIG. 1 is a graph showing the relationship between the wavelength of infrared rays and dark current, which is relevant to the present invention. That is, in Figure 1, an insulating GaAs layer provided on an n-type AlGaAs layer is used as a sample, and this is heated at 77°.
It is a graph of data obtained by cooling to a low temperature of K (liquid nitrogen temperature) and measuring its dark current by changing the wavelength of infrared rays.

As is clear from the graph, the dark current is large at a wavelength of 0.5 to 1 μm, but at a wavelength of 1 μm, the dark current decreases to 1.2 μm.
At long wavelengths of μm or more, there is almost no effect of irradiation with infrared light. The dark current ratio is the ratio of the dark current inside the black box to the dark current inside the black box, and the dark current ratio -1 means the same as inside the black box.

Therefore, by performing a probe test in infrared light in a long wavelength range of at least 1 μm or more, it is possible to accurately obtain low-temperature characteristics as in a black box.For example, the test head of a low-temperature autoprober is Create it like this. That is, the box 20 is wrapped in a heat-retaining material, and the movable stage 12 on which the wafer 11 is placed is made of a Talaiohesod (a cooling body capable of cooling down to 15°K).
Vacuum suction is applied to the inside of the box 20, and helium (li) is pumped from the other side.
e) Allow gas to flow. Then, the wafer 11 is irradiated with infrared light with a wavelength of 1.2 μm from the infrared light source 14 through the transmission window 16, and the probe card 13 is aligned while being visually observed with the microscope 15. In this way, since it is not in a vacuum, the manipulator can be finely adjusted, automatic feeding becomes easy, and a probe test using an autoprober can be performed.

In this way, a semiconductor device operated at a low temperature can be probe tested at a temperature as low as about 77°K, thereby reducing the number of man-hours and stabilizing device characteristics at low temperatures.

In the auto blower according to the present invention, when using a probe card, there is no need to make fine adjustments to the individual needles, so the inside of the box 20 can be kept in a vacuum state, and the pins of IC, etc. It can also be used in cases where there are many numbers.

[Effects of the Invention] As can be seen from the above description, the present invention enables low-temperature probe testing of semiconductor devices operating at low temperatures, contributing to improved reliability and cost reduction.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship between infrared wavelength and dark current, FIG. 2 is a schematic diagram of a test head for a low temperature autoprober according to the present invention, and FIG. 3 is a schematic diagram of a conventional test head. In the figure, 1 is a wafer, 2 and 12 are movable stages, and 3
is a probe, 4 is a visible light source, 5 is a microscope,
10.20 is a box, 13 is a probe card,
14 is an infrared light source, 15 is an infrared microscope, and 16 is a transmission window. Temple, 7 and the heart of the long-term relationship 1-Xiao 5, Mineden Geng and Shin-Tsai chart 1st figure, 4th grade and 8th grade. Adding force, 3 auto 7, low 8, Saiseiji zo @ 2 diagrams

Claims (1)

[Claims] In low-temperature autoprobers that measure device characteristics by bringing probes into contact with semiconductor devices on a wafer at low temperatures below room temperature, infrared light in a long wavelength band of 1 μm or more is irradiated to position the probes. Auto prober for low temperature.