JPH041735Y2 - - Google Patents

Description

[Detailed explanation of the invention] Industrial application field This invention is a Ga-As based semiconductor or a Ga-In-
This invention relates to a sample cooling and holding device for cooling and holding semiconductor samples when testing various semiconductors such as As-based semiconductors at low temperatures using light or other electromagnetic waves.

Conventional technology When manufacturing semiconductors such as Ga-As, various defects such as lattice defects are detected by irradiating light onto a semiconductor sample placed in a low-temperature environment for quality control purposes. . In such cases, there are two types of devices for cooling and holding semiconductor samples at low temperatures: devices that immerse the semiconductor sample directly in a cooling liquid such as liquid nitrogen, and devices that are installed at a distance from the semiconductor sample. A device in which a cooling liquid such as liquid nitrogen in a cooling tank is connected with a semiconductor sample through a good heat conductive material such as copper, and the semiconductor sample is indirectly cooled by heat conduction (for example, Japanese Patent Application Laid-Open No. 57-40950 Official bulletin or Jikaisho
51-72058) is known.

In the former type of cooling device, which uses coolant immersion, bubbles in the coolant may prevent accurate light detection, and in some cases, there may be problems with light absorption by the coolant, resulting in poor detection. There is a problem that the error becomes large, and furthermore, the sample temperature is limited only to the temperature of the coolant itself, and there is a drawback that testing at various temperatures is not possible.

On the other hand, the latter indirect cooling type device does not have the problems of the immersion method, and by installing a heater near the sample and controlling the amount of heating by the heater, it is possible to maintain a temperature range from around the temperature of the cooling liquid itself to higher than that. Although tests can be performed at various temperatures, conventional devices of this type have had various problems due to their structure, as described below.

An example of a conventional indirect cooling type device is shown in FIG. In FIG. 2, a sample chamber 4 is formed below a cooling tank 3 that contains a cooling liquid 1 such as liquid nitrogen and is surrounded by a vacuum insulation layer 2. Furthermore, a heat transfer piece 5 made of a material with good thermal conductivity such as copper is provided so as to penetrate from the inside of the cooling tank into the sample chamber 4. A holding part 7 for holding the semiconductor sample 6 is formed, and a heater 8 for adjusting the temperature of the sample is attached near the holding part 7. In addition, sample chamber 4
Window portions 9 are formed on both sides to transmit light. When replacing the semiconductor sample 6 in such a conventional semiconductor cooling device using an indirect cooling method, it is necessary to open the sample chamber 4, but if the sample chamber 4 is opened, outside air can enter the inside of the sample chamber 4. If there is a coolant 1 such as liquid nitrogen in the cooling tank 3 at that time, the coolant will be transferred from below. Most of it turns into gas due to heat and is lost. Therefore, before opening the sample chamber 4 for sample exchange, the coolant 1 in the cooling tank 3 must be drained out in advance. Furthermore, after replacing the sample and closing the sample chamber 4, the inside must be evacuated and the cooling liquid 1 must be injected into the cooling tank 3 again, and at this time the sample temperature reaches a predetermined low temperature. It will take a considerable amount of time. Therefore, a great deal of effort and time is required to exchange the sample, and the loss due to the removal of the coolant during that time and gasification during injection becomes a non-negligible amount. Furthermore, if the sample chamber 4 is opened and outside air flows in as described above, a large amount of water may adhere to the inner surface of the window 9 due to moisture in the outside air, which may interfere with subsequent testing.

Problems to be solved by this invention As mentioned above, the conventional specimen cooling and holding device for semiconductor inspection using the indirect cooling method (thermal conduction method) as shown in Figure 2 eliminates the drawbacks of the direct cooling method (immersion method). Although it is possible, it takes a lot of time and effort to exchange samples, and the inspection work efficiency is low.
In addition, there was an unavoidable problem of high costs due to loss of coolant, and there was also the problem of water adhering to the sample chamber during replacement.

This idea was made in view of the above circumstances, and it improves the conventional cooling and holding device for semiconductor inspection using indirect cooling, making it possible to easily and easily exchange samples without requiring a lot of time and effort. It is an object of the present invention to provide an apparatus which can reduce the loss of cooling liquid and which can avoid water from adhering to the inner surface of the window of the sample chamber during replacement.

Means for solving the problem The sample cooling and holding device for semiconductor inspection of this invention is
Basically, a cooling tank that houses the cooling liquid is surrounded by an outer tank, a vacuum insulation layer is formed between the outer tank and the cooling tank, and an inner cylinder that has a hollow cylindrical shape as a whole. A sample chamber is disposed so as to vertically penetrate through the center of the cooling tank, and has a hollow section at the lower end of the inner cylinder that communicates with the internal space of the inner cylinder. A holding shaft is formed to protrude into the vacuum heat insulating layer, and further includes a holding shaft provided in the inner cylinder with a sample holding part at its lower end for holding a semiconductor sample, so that the sample holding part is located in the sample chamber. It is inserted so that it can be inserted and removed from above, and at least a part of the entire length of the inner cylinder body that is immersed in the cooling liquid in the cooling tank is a heat transfer part made of a material with good thermal conductivity. A heat transfer part is formed in contact with the heat transfer part, and the part of the holding shaft from the heat transfer part to the sample holding part is made of a good heat transfer material, and the inner cylinder has a dryer inside. The sample chamber is configured to be supplied with gas, and windows are formed on the side surface of the sample chamber at the lower end of the inner cylindrical body and the corresponding lower side surface of the outer tank. It is something.

Here, it is preferable that the holding shaft is provided with an elastic member for applying a pressing force in a direction to bring the heat transfer portion into contact with the heat transfer portion of the inner cylinder.

The inner surface of the heat transfer portion of the cylindrical body is formed into a tapered surface whose diameter decreases downward, while the outer surface of the heat transfer portion of the holding shaft is formed with a reverse taper surface that follows the taper of the inner surface of the heat transfer portion. It is preferable that the heat transfer portion of the cylindrical body and the heat transfer target portion of the holding shaft come into wide surface contact with each other on the tapered surface.

Function: In the sample holding and cooling device for semiconductor testing of this invention, the semiconductor sample is supported by the sample holding portion at the tip of the holding shaft inserted into the inner cylinder. Therefore, in the semiconductor sample, the low temperature caused by the cooling liquid such as liquid nitrogen in the cooling tank is transmitted from the heat transfer part of the inner cylinder to the tip of the holding shaft via the heated part of the holding shaft that is in contact with it. Cooled by When replacing the sample, the holding shaft can be removed from the inner cylinder, but the vacuum of the vacuum insulation layer is not broken when the holding shaft is removed, so the cooling tank is vacuum insulated around it even when the sample is replaced. This means that Moreover, since the inner cylinder is configured to be supplied with dry gas, preferably an inert gas such as nitrogen gas or helium gas, the dry gas is supplied into the inner cylinder not only during inspection but also when replacing samples. If this gas is supplied, this gas becomes a low-temperature gas that is cooled by heat exchange with the inner cylinder wall surface, which prevents outside air from rapidly flowing in during sample exchange, and keeps the inner cylinder and sample chamber at low temperatures. It is maintained. In this way, vacuum insulation around the cooling tank is maintained even during sample exchange, and the inner cylinder and sample chamber inside the cooling tank are also kept at a low temperature. Since there is no need to drain the coolant, the effort and time required to drain and re-inject the coolant can be saved, and loss of coolant at that time can also be prevented. In addition, as mentioned above, the interior of the inner cylinder and the sample chamber are kept at a low temperature even during sample exchange, so the temperature of the new sample drops quickly after the sample is exchanged, thus shortening the time it takes for the sample to cool down. . Furthermore, since outside air does not immediately flow into the sample when replacing the sample, the inner surface of the window portion of the sample chamber, etc., is prevented from getting wet with moisture in the outside air.

In particular, if the holding shaft is pressed by an elastic member as described above, good contact between the inner surface of the heat transfer portion of the inner cylinder and the outer surface of the transmitted portion of the holding shaft is maintained, and the Transmission resistance is reduced. In addition, if the inner surface of the heat transfer part of the inner cylinder and the outer surface of the heat transfer target part of the holding shaft are configured to be in contact with each other at a tapered surface, the contact area on both sides will be expanded, and the heat transfer between both sides will be even better. .

Embodiment FIG. 1 shows a sample cooling and holding device for semiconductor testing according to an embodiment of this invention.

A sample chamber accommodating section 12 is continuously formed on the lower side of the outer tank 11 which has a cylindrical shape as a whole, and an outer window section made of a transparent material such as quartz is located at a symmetrical position of the sample chamber accommodating section 12. 13 and 14 are provided. Further, inside the outer tank 11, a cylindrical cooling tank 15 is arranged. The cooling tank 15 stores a cooling liquid 16 such as liquid nitrogen, and is provided with a cooling liquid supply pipe 17 and a discharge pipe 18 for discharging the gasified cooling liquid on its upper surface. Further, a vacuum exhaust valve 19 is provided on the upper surface of the outer tank 11, and by evacuating the inside of the outer tank 11, a vacuum insulation layer 20 is formed between the inner surface of the outer tank 11 and the outer surface of the cooling tank 15. It is said that The interior of the sample chamber accommodating section 12 is also vacuum insulated.

In the center of the cooling tank 15, there is an inner cylindrical body 21 having a hollow cylindrical shape as a whole and passing through it vertically.
is installed. This inner cylindrical body 21 has a large diameter cylindrical part 21A at the upper part and a small diameter cylindrical part 21B which protrudes into the sample chamber accommodating part 12 at the lower part. A heat transfer section 22 made of a good heat transfer material such as the like is provided, and a sample chamber 23 is further provided at the lower end of the small diameter cylindrical section 21B.
The heat transfer section 22 is provided at a position where it is immersed in the cooling liquid 16 in the cooling tank 15, and has fins 22A formed on its outer surface, and fins 22A formed on its inner surface that decrease in diameter toward the bottom. A tapered surface 22B is formed. On the other hand, on both the left and right sides of the sample chamber 23,
Inner window portions 24 and 25 made of a transparent material such as quartz glass are provided at positions corresponding to the aforementioned outer window portions 13 and 14.

A connecting cylinder 28 is removably attached to the upper end of the large diameter cylinder part 21A of the inner cylinder 21 via a tightening ring 27, and the upper open end of the connecting cylinder 28 is connected to the lid 30. It is twisted closed. Further, in the upper part of the inner cylinder body 21, there is a gas supply pipe 32 for supplying an inert dry gas such as nitrogen gas or helium gas into the inside of the inner cylinder body, and a gas supply pipe 32 for evacuating the inside of the inner cylinder body 21 to the low temperature. A vacuum exhaust pipe (not shown) and a safety valve 34 for replacing gas are connected.

Furthermore, a holding shaft 35 is inserted into the inner cylindrical body 21 by penetrating the lid body 30. This holding shaft 3
5 is provided with a heat transfer part 36 made of a good heat transfer material such as copper on the lower end side, and a heater board 37 also made of a good heat transfer material such as copper at the lower end of the heat transfer part 36.
A sample holding portion 38 made of a good heat conductive material such as copper is provided through the sample holding portion 38.

The heat transfer portion 36 of the holding shaft 35 is connected to the inner cylindrical body 21
A tapered surface 36A whose diameter decreases downward is formed on the outer surface so as to fit the tapered surface 22B on the inner surface of the heat transfer portion 22. Further, the heater substrate 37 includes a heater 39 for adjusting the temperature of the semiconductor sample S held in the sample holding section 38.
is provided.

Furthermore, a tapered surface 36A of the heat transfer target part 36 is attached to the upper end of the holding shaft 35 by pressing the holding shaft 35 downward.
An elastic member 42 is attached for bringing the heat transfer portion 22 into close surface contact with the tapered surface 22B of the heat transfer portion 22 of the inner cylinder body 21. That is, the upper end of the holding shaft 35 is inserted through a hollow male threaded member 43 fixed to the lid body 30, and the elastic force is formed between the inner circumferential surface of the hollow male threaded member 43 and the outer circumferential surface of the upper end of the holding shaft 35. A coil spring as a member 42 is disposed, and the hollow male screw member 4
By tightening a cap 44 screwed onto the upper part of the holding shaft 35, a downward pressing force is applied to the holding shaft 35. Note that the connection tube 28 above the inner cylinder body 21 is provided with an outlet 45 for taking out a signal line from a temperature detector such as a thermocouple (not shown), heater power supply wiring, and the like.

In the embodiments described above, when the apparatus is in use, the surroundings of the cooling tank 15 and the sample chamber 23 are evacuated and vacuum-insulated. Further, a cooling liquid 16 such as liquid nitrogen is stored in the cooling tank 15 . Further, inside the inner cylinder body 21, a gas supply pipe 3 is provided.
2, a dry gas, preferably an inert gas such as nitrogen gas or helium gas, is introduced, and this gas is immediately cooled to a low temperature by heat exchange with the inner wall of the inner cylinder 21, and therefore the inner cylinder 21 and the sample chamber 23 are supplied with low temperature gas such as low temperature nitrogen gas. Of course, before introducing the dry gas, it is necessary to exhaust the air in the inner cylinder 21 and the sample chamber 23 and replace it with dry gas.

When inspecting the semiconductor sample S, the sample S is held on the holding shaft 3.
It is inserted into the sample chamber 23 while being attached to the sample holder 38 at the tip of the sample 5. and holding shaft 3
5 is pressed downward by a coil spring 42 as an elastic member, so that the tapered surface 36A of the heat transfer portion 36 becomes the tapered surface 2 of the heat transfer portion 22 of the inner cylindrical body 21.
Close surface contact with 2B. In this state, the low temperature of the cooling liquid 16 such as liquid nitrogen in the cooling tank 15 is lowered by the inner cylinder 21.
The heat is transmitted from the heat transfer portion 22 of the holding shaft 35 to the heat transfer target portion 36 of the holding shaft 35, and from the heat transfer target portion 36 to the sample S via the heater substrate 37 and the sample holder 38. Then, light etc. are incident on the sample chamber 12 through the outer windows 13 and 14 and the inner windows 24 and 25 of the sample chamber 23 for semiconductor inspection, and the sample transmitted light or the sample reflected light is taken out. Defect inspection for S is performed. Here, by activating the heater 39 and controlling the degree of heating by the heater 39, it is possible to not only operate at a predetermined low temperature determined by the temperature of the coolant such as liquid nitrogen, but also at a relatively high temperature. It is possible to adjust the sample temperature to a temperature of 1, and therefore it is possible to inspect the sample at any temperature.

When the inspection of one semiconductor sample is finished and the next sample is to be inspected, the tightening ring 27 is loosened, the connecting cylinder 28 is removed from the inner cylinder 21, and the holding shaft 3 is removed.
5 is pulled out from the inner cylindrical body 21. At this point, dry gas such as nitrogen gas or helium gas as described above is continuously supplied into the inner cylinder body 21.
1 and the sample chamber 23 are filled with low-temperature gas to prevent outside air from rapidly flowing in. Therefore, the temperature inside the inner cylinder body 21 and the sample chamber 23 hardly rises, so there is almost no loss of the cooling liquid 16 in the cooling tank 15 due to heat transfer from the inner cylinder body 21 side. Vacuum insulation is maintained around 15. Therefore, there is no need to drain the coolant 16 especially when replacing the sample. In addition, as mentioned above, the sample chamber 2
3 is filled with low-temperature gas even when the sample is replaced, so that water will not adhere to the inner surfaces of the inner windows 24 and 25 due to the inflow of outside air.

The holding shaft 35 with the new sample attached is attached to the inner cylinder body 2
1, and connect and fix by the reverse method to that described above. At this time, the tapered surface 36A of the heat transfer portion 36
When it comes into contact with the tapered surface 22B of the heat transfer portion 22 of the inner cylinder 21, the low temperature of the cooling liquid 16 in the cooling tank 15 is immediately transferred to the sample S, and the temperature of the sample S quickly reaches a predetermined low temperature.

In the illustrated embodiment, a pair of outer windows 13 and 14 are provided on the left and right sides of the sample chamber accommodating section 12 at the lower part of the outer tank 11, and a pair of outer windows 13 and 14 are provided on the left and right sides of the sample chamber 23 corresponding to the outer windows 13 and 14. Although a pair of inner windows 24 and 25 are provided, depending on the specific method and type of semiconductor inspection, it is not always necessary to form a pair of these windows, and it is possible to form one pair of each window. It's okay to stay. The point is that at least one outer window section and at least one corresponding inner window section should be formed in order to transmit electromagnetic waves, light, etc. for semiconductor inspection.

Effects of the invention As is clear from the above explanation, according to the specimen cooling and holding device for semiconductor testing of this invention, vacuum insulation is maintained around the cooling tank even when replacing the specimen, and inside the inner cylinder and the specimen chamber. Since it is kept at a low temperature, there is no need to temporarily drain the cooling liquid such as liquid nitrogen from the cooling tank. This saves the time and effort required to drain and re-inject the cooling liquid when exchanging samples. The temperature of the sample also drops quickly. Therefore, a remarkable effect can be obtained in that the labor and time required for sample exchange are significantly reduced compared to the conventional method. Furthermore, as mentioned above, since it is not necessary to draw out and re-inject the coolant when replacing the sample, there is no loss of coolant at that time, and it is possible to significantly reduce the amount of coolant consumed and reduce costs. Furthermore, since the sample chamber will not get wet due to outside air entering during sample exchange, there is no risk of interfering with subsequent inspections. Therefore, this device can be applied to low-temperature inspections of various semiconductors using light, electromagnetic waves, etc. It is extremely useful.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view showing a specimen cooling and holding device for semiconductor testing according to an embodiment of this invention, and Fig. 2 is a schematic vertical cross-sectional view showing an example of a conventional indirect cooling type sample cooling and holding device for semiconductor testing. It is a diagram. 15...Cooling tank, 16...Cooling liquid, 20...Vacuum insulation tank, 21...Inner cylinder body, 22...Heat transfer part, 2
2B...Tapered surface, 23...Sample chamber, 32...
Gas supply pipe, 35...Holding shaft, 36...Heat transfer target part, 36A...Tapered surface, 38...Sample holding part, 39...Heater, 42...Elastic member (coil spring), S...Semiconductor sample.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A cooling tank containing a cooling liquid is surrounded by an outer tank, a vacuum insulation layer is provided between the outer tank and the cooling tank, and the entire cooling tank is a hollow cylinder. An inner cylindrical body having a shape is disposed so as to vertically penetrate through the central part of the cooling tank, and a sample chamber is provided at the lower end of the inner cylindrical body, the hollow part communicating with the internal space of the inner cylindrical body. is formed so as to protrude into the vacuum heat insulating layer below the cooling tank, and further inside the inner cylinder, a holding shaft is provided with a sample holding portion at the lower end for holding the semiconductor sample. The holding part is inserted removably from above so that the holding part is located, and at least a part of the entire length of the inner cylinder body that is immersed in the cooling liquid in the cooling tank is a heat transfer part made of a material with good thermal conductivity. On the other hand, the holding shaft is formed with a heat transfer part in contact with the heat transfer part, and the part of the holding shaft from the heat transfer part to the sample holding part is formed of a good heat transfer material, and the inner cylinder The body is configured such that dry gas is supplied into the interior thereof, and windows are formed on the side surface of the sample chamber at the lower end of the inner cylindrical body and the corresponding lower side surface of the outer tank. Sample cooling and holding device for semiconductor testing. (2) The holding shaft is provided with an elastic member for applying a pressing force in the direction of bringing the heat transfer portion into contact with the heat transfer portion of the inner cylinder body, as described in claim 1 of the utility model registration claim. sample cooling and holding device for semiconductor testing. (3) The inner surface of the heat transfer portion of the inner cylinder is formed into a tapered surface whose diameter decreases downward, while the outer surface of the heat transfer portion of the holding portion has a tapered surface along the taper of the inner surface of the heat transfer portion. A sample cooling and holding device for semiconductor testing according to claim 1, wherein a tapered surface is formed.