JPS6236387B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a low temperature testing apparatus for semiconductor wafers.

Recently, there has been active development of semiconductor devices that operate at low temperatures, for example, in order to further increase the calculation speed of computers. For this purpose, testing of devices at low temperatures is carried out by cutting out individual chips formed on a semiconductor wafer, attaching test leads to each chip, applying protective measures to each chip, and then exposing the chip to a cryogen such as liquid nitrogen. The method used is to immerse it in water and test its electrical characteristics. However, it is natural that such a method requires a huge amount of time, effort, and expense for testing.

The purpose of the present invention is to eliminate the above-mentioned drawbacks associated with the conventional testing of semiconductor devices at low temperatures, and to test individual chips formed on a wafer at low temperatures using a probe card as in the case of testing at room temperature. An object of the present invention is to provide a semiconductor wafer low-temperature testing device capable of sequentially and continuously testing various conditions.

For the above purpose, the present invention includes a built-in holding stand for the semiconductor wafer to be tested, an insulating container containing a cryogen for cooling the semiconductor wafer, and a see-through window for seeing through the tip of the probe. a probe card, a heat insulating container stand on which the heat insulating container is placed, a probe card holding means for holding the probe card, and a microscope for observing the tip of the probe of the probe card through the see-through window of the probe card. and a means is provided in the opening of the upper part of the insulating container so that the probe card can be displaced three-dimensionally in close contact with the opening over a predetermined range while maintaining airtightness between the probe card and the insulating container stand and the probe. The device comprises a device in which at least one of the card holding means is provided with means for displacing the relative position of the card holding means.

Embodiments of the present invention will be described below based on the drawings. FIG. 1 shows the configuration of an embodiment of the present invention. The tips of the probes 211 (only two are shown in the figure) extending downward from the intermediate opening 203 of the probe card 202 and the semiconductor wafer 212 to be tested are seen through the microscope 11 through the see-through window made of the transparent quartz plate 201. be done. Holding stand 21 for wafer 212
4 is mounted in an insulated container, ie a dewar container consisting of an outer container 218, an insulated vacuum 219 and an inner container 217, and is kept cold with a suitable cryogen, for example liquid nitrogen 220. The holding table 214 is provided with means for detecting the highest level of liquid nitrogen 220 and a wafer cooling thermometer, but these are not shown in this figure. The entire dewar container is mounted on a rotary table 1 which is configured to be freely rotatable with a lever 15.
4 and a slide bed 16 which can be moved left and right and back and forth using screws 17 and 18. The probe card 202 is held by the card holder 12 and can be vertically displaced by a vertical adjustment screw 13. A neck 207 extends upward from the top plate 210 of the dewar container,
Its upper end is in contact with the probe card 202 via an O-ring 204, and its neck 207 is connected to the bellows 202.
It is surrounded by 7a. The lower end of the bellows 207a is welded to the top plate 210 of the dewar container.
The top end only maintains mechanical contact with the probe card 202.

In the above configuration, after testing a certain chip on the wafer 212, operate the vertical adjustment screw 13 to adjust the probe card 202 by 0.1 to 0.3.
The probe 211 was lifted up by 1 mm and removed from the terminal of the chip, and the screws 17, 18 and the lever 15 were adjusted to displace the entire dewar container so that the probe 211 corresponded to a predetermined test terminal of the chip to be tested next. After that, the probe card 202 is lowered again using the vertical adjustment screw 13 to bring the probe 211 into contact with a predetermined test terminal of the chip. The amount of vertical displacement of the probe card 202 of 0.1 to 0.3 mm is within the elasticity of the O-ring 204, and therefore, when the dewar container is displaced, there is a gap between the O-ring 204 and the contact portion of the probe card 202. Slippage occurs while airtightness is maintained, and the probe 211 and wafer 2
12 does not cause any macroscopic thermal disturbance within the dewar container. Note that the bellows 207a acts as a spring that pushes the probe card 202 upward due to its elasticity, thereby facilitating the above-described upward displacement operation of the probe card.

As described above, according to the present invention, instead of cutting out each chip formed on a wafer and individually testing it at low temperature, the entire wafer is kept at a low temperature and the chips are tested at room temperature.
It is clear from the above explanation that it has become possible to test individual chips one after another, and that this will have an immeasurable contribution to the efficiency of testing semiconductor devices at low temperatures. Regarding the dewar container, which plays an important role in the structure of the present invention,
Some supplementary explanation will be given based on FIG.

In FIG. 2, a pipe 223 is an exhaust pipe for eliminating the heat insulating space 219 of the dewar container.
After evacuation, it is sealed by welding or by installing a vacuum valve. The main body of the dewar container is made of stainless steel, which has poor thermal conductivity, and a metal with good thermal conductivity, such as copper, is used for the wafer holder 214 provided at the center of the interior. Thermocouples 216 and 213 are
These are used to detect the maximum liquid level of the injected liquid nitrogen and to detect the temperature of the top surface of the wafer holder, respectively. The leads of both thermocouples are led to the outside through a hook seal 208. Liquid nitrogen 220 is supplied into the dewar through a liquid nitrogen supply pipe 222, and evaporated gas is discharged to the outside from a pipe 205. A heater 215 wrapped around the outer circumference of the dewar inner container and a neck 2 provided on the top plate 210.
When taking out the wafer after the test, the heater 206 wrapped around the dewar heats the entire dewar to room temperature after taking out the liquid nitrogen inside the dewar and before removing the probe card 202. It is provided to prevent dew condensation. The activated carbon 221 in contact with the outside of the bottom plate of the inner container 217 of the dewar adsorbs gas remaining in the heat insulating space. In addition, before supplying liquid nitrogen to the dewar, the liquid nitrogen supply pipe 222 or the pipe 20 for releasing evaporated nitrogen gas is
It is necessary to introduce dry nitrogen gas into the dewar through 5 to replace the air inside with dry nitrogen.
After liquid nitrogen is injected, the liquid nitrogen supply pipe 222 and the pipe 205 for releasing evaporated nitrogen gas are connected with a highly elastic rubber tube with a small cut in the length direction of the side surface. Therefore, the evaporated nitrogen gas inside the dewar is gradually released into the atmosphere through the cuts against the elasticity of the rubber, and the inside of the dewar is always kept at a pressure slightly higher than atmospheric pressure, so air cannot enter the dewar. Prevented.

Further, as another embodiment of the present invention, the means for maintaining airtightness between the probe card and the dewar container when they are displaced may be constructed as shown in FIG. That is, the O-ring 20 provided on the neck portion 207 in FIGS. 1 and 2
4 on the bellows 207a, O
The ring 204 is pressed against the lower surface of the probe card 202 by the elasticity of the bellows 207a.

[Brief explanation of the drawing]

FIG. 1 shows the structure of an embodiment of the present invention, and FIG. 2 is a detailed view of a dewar container constituting the embodiment of the present invention. FIG. 3 shows, for use in another embodiment of the present invention,
FIG. 3 is a diagram showing the structure of a contact portion between a dewar container and a probe card. 11...Microscope, 12...Card holder, 1
3... Probe card height adjustment screw, 14...
Rotary table, 15...Rotary lever, 16...Slide bed, 17, 18...Slide bed movement adjustment screw, 201...Probe card transparent window,
202... Probe card, 204... Q-ring, 207... Neck, 207a... Bellows,
211...Tip, 212...Semiconductor wafer, 2
14... Semiconductor wafer holding stand, 217... Dewar inner container, 218... Dewar outer container, 2
19...Insulated vacuum space, 220...Liquid nitrogen.

Claims (1)

[Claims] 1. A heat insulating container containing a holding stand for the semiconductor wafer to be tested and containing a cryogen for cooling the semiconductor wafer, a probe card provided with a see-through window for seeing through the tip of the probe, and the heat insulating container. comprising an insulating container stand on which the probe card is mounted, a probe card holding means for holding the probe card, and a microscope for observing the tip of the probe of the probe card through the see-through window of the probe card,
Provided at the opening in the upper part of the heat insulating container is a means that allows the probe card to be displaced three-dimensionally in close contact with the opening while maintaining airtightness over a predetermined range;
A semiconductor wafer low temperature testing apparatus, wherein at least one of the heat insulating container pedestal and the probe card holding means is provided with means for displacing the relative positions thereof.