JP3092343B2 - Heating element cooling device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling device for a heating element which cools the heating element and maintains it at a predetermined temperature with high precision, and more particularly to a method for inspecting electrical characteristics of an integrated circuit formed on a semiconductor wafer. The present invention relates to a heating element cooling device suitable for cooling a heating element such as a semiconductor wafer that generates heat when supplied with power.

[0002]

2. Description of the Related Art Conventionally, in this type of semiconductor wafer cooling apparatus, as shown in FIG. 8, a cooling block 4 having a built-in cooling pipe 6 through which a low-temperature cooling fluid supplied from a refrigerator 5 circulates is provided. The semiconductor wafer 1, which is a heating element, is placed, and this semiconductor wafer is vacuum-chucked by the vacuum pump 8 through the vacuum exhaust port 15 provided in the cooling block 4, and the semiconductor wafer 1 is contacted with the cooling block 4 by conduction. Cooling was taking place. At this time, the temperature of the semiconductor wafer greatly changes due to the contact thermal resistance between the cooling block and the semiconductor wafer, and the temperature distribution may be non-uniform. Therefore, a method for stabilizing the contact thermal resistance has been proposed. As one of them, Nikkei Electronics, June 17, 1985 (No. 371) describes a structure in which a high thermal conductive grease called thermal compound is applied to a contact surface between a semiconductor package and a thermal conductor. .

[0003]

When a semiconductor wafer as a heating element is cooled, even if the surface accuracy of the contact surface of the cooling member is finished with high accuracy and the surface roughness and warpage are about several μm, the contact surface between the contact surfaces is cooled. No fluid intervenes near the vacuum chuck,
Air is interposed on the outer periphery of the semiconductor wafer. In the part where fluid does not intervene, heat conduction becomes extremely poor,
The portion where air intervenes is not as high as in vacuum, but the thermal resistance between the objects increases because the thermal conductivity of air is low. In addition, when dust of about several μm adheres between the contact surfaces, the contact thermal resistance greatly varies. For this reason, it is difficult to cool the semiconductor wafer that generates high heat while maintaining the temperature with high accuracy.

The above-mentioned prior art has been proposed to solve this problem, but this method also has the following disadvantages. In other words, when a structure that applies and cools high thermal conductive grease to cool semiconductor wafers is used, in order to control the temperature of semiconductor wafers that repeat frequent attachment and detachment with high precision, the amount of grease to be applied must be exactly constant. Must be kept. That is, since the contact thermal resistance is controlled by the thickness of the grease interposed between the contact surfaces, it is indispensable to keep the amount of the grease constant. However, it is difficult to keep the grease thickness constant for a large number of semiconductor wafers in a short time. Further, after cooling the semiconductor wafer, it is necessary to clean the grease applied to the contact surface, which increases the time and labor required for the process. Further, incomplete cleaning has a great effect on the subsequent steps.

As another method for stabilizing the contact thermal resistance, there is known a method of supplying a highly thermally conductive helium gas between a contact surface between a semiconductor wafer and a cooling body in a semiconductor CVD apparatus. However, when the helium gas is injected, the semiconductor wafer is slightly pushed up by the supply pressure of the helium gas, so that the desired adsorption action with the semiconductor wafer cannot be obtained. Further, when the pressure of the helium gas is reduced in a narrow space, the thermal conductivity is reduced. Therefore, when the pressure is reduced to adsorb the wafer, the cooling performance is reduced. Then, the gas supplied to the cooling surface and contributing to the heat transfer diffuses to the surroundings, and affects processes around the surroundings.

SUMMARY OF THE INVENTION An object of the present invention is to cool a heating element such as an LSI chip which can efficiently cool a heating element having a large amount of heat without contaminating it in a short time while maintaining its temperature and surface flatness with high accuracy. It is to provide a device.

Another object of the present invention is to provide a high-performance cooling of a region including a heat-generating chip and a decrease in cooling performance of other non-heat-generating chip regions as compared with a region including a heat-generating chip. The purpose is to make the temperature distribution of the chip uniform.

It is still another object of the present invention to provide a control device for effectively supplying a highly thermally conductive fluid to a gap between a heating element and a cooling element for high-performance cooling.

[0009]

In order to achieve the above-mentioned object, the present invention provides a heating element in contact with a cooling body, a supply and recovery mechanism for a heat conductive fluid, and a heating and cooling mechanism provided between the heating element and the cooling body contact surface. A high thermal conductive fluid is jetted and filled to reduce contact thermal resistance by conduction of the high thermal conductive fluid.

Another feature of the present invention is that a structure for controlling the supply pressure and the recovery pressure of the high thermal conductive fluid is added, the supply pressure is set lower than the ambient pressure of the heating element, and the recovery pressure is further reduced. By doing so, a pressure difference is generated to reduce the contact thermal resistance, and at the same time, a mechanism is provided for adsorbing and fixing the heating element on the surface of the cooling element.

Still another feature of the present invention is that when a highly thermally conductive fluid supplied from a minute gap between contact surfaces is guided to a recovery port having a relatively large opening area, a sudden pressure drop occurs near the recovery port. When the high thermal conductive fluid is a gas, the fluid becomes low temperature due to adiabatic expansion, and when the high thermal conductive fluid is a liquid, an additional cooling effect such as heat of vaporization due to vaporization due to an evaporating action. Performance is to be improved.

Still another feature of the present invention is that, when the heating element is divided into a plurality of partial areas and the partial areas generate heat independently, each of the partial areas of the heating element is independently thermally conductive. A fluid supply / recovery mechanism is provided to control the supply / recovery of the highly thermally conductive fluid only to the heated partial area.

Still another feature of the present invention is that when the heating portion of the heating element is under load and is pressed against the cooling body, the supply pressure is lower than the load pressure and the recovery pressure is lower than the ambient pressure. By setting and controlling the weighting mechanism and the supply mechanism of the high thermal conductive fluid in synchronization, a mechanism that raises the pressure of the high thermal conductive fluid as compared to the case without load while keeping the heating element adsorbed on the cooling body It is provided.

[0014]

According to the present invention, an object is to contact a minute gap between a heating element and a cooling element while supplying a highly thermally conductive fluid while supplying air, and at the same time, to recover air that has been intervening at this contact surface. The gap is filled with a highly thermally conductive fluid by recovering from the hole, and the contact thermal resistance between the heating element and the cooling element can be reduced. At this time, dust adhering to the contact surface of the heating element due to the ejection of the fluid is removed, and the performance can be prevented from deteriorating due to the dust being caught between the contact surfaces.

Further, according to the present invention, by setting the supply pressure of the high heat conductive fluid lower than the ambient pressure of the heating element and setting the recovery pressure further lower than the supply pressure, a pressure difference is generated and the cooling element is set. It is possible to avoid a decrease in cooling performance due to the heating element being adsorbed on the surface and the heating element warping and widening the gap with the cooling body.

Further, according to the present invention, the heating element divided into partial regions is supplied with a high thermal conductive fluid only to the region including the heat generating portion to perform high-performance cooling, and the cooling performance around the region is reduced. , The escape of heat from the heat generating portion to the surroundings can be reduced, and the temperature distribution of the heat generating element can be made uniform.

Further, according to the present invention, when the heating element is under load, the supply pressure of the high thermal conductive fluid is increased in a range lower than the load pressure, and is increased only in the area where the load is applied. By supplying high heat conductive fluid with pressure,
It is possible to use a highly thermally conductive gas having a property that the thermal conductivity is reduced at a low pressure without floating the heating element from the cooling element under advantageous conditions.

[0018]

An embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a vertical sectional view of a heating device cooling device according to a first embodiment of the present invention. In this figure, a semiconductor wafer 1 is an object to be evaluated for electrical characteristics, and a silicon wafer is often used. When evaluating a large number of integrated circuits formed on the upper surface of the semiconductor wafer 1 one by one, power is supplied to a power supply circuit and a signal circuit in the integrated circuit each time, and the semiconductor wafer 1 becomes a heating element.
When the electrical characteristics of the integrated circuit are evaluated, power is supplied at a constant temperature in order to eliminate the influence of temperature change on the characteristics, so that the semiconductor wafer 1 needs to be cooled.

On top of the semiconductor wafer 1, the semiconductor wafer 1
A contact probe pin 2 for supplying power to the integrated circuit and extracting a test signal and a probe card 3 for holding the probe pin 2 are provided. The semiconductor wafer 1 is placed on the upper surface of the cooling block. In FIG. 1, the contact state between the cooling block 4 and the semiconductor wafer 1 is schematically illustrated as being in contact with each other via an equivalent gap. In both cases, the surface roughness and the warpage are on the order of several μm. Therefore, when they actually come into contact with each other, the microscopic irregularities on the surface collide with each other, and a minute gap exists in the concave. Since such a microscopic situation is difficult to illustrate, the simulated equivalent gap is shown as described above to indicate the existence of a minute gap in the concave portion.

The heating element cooling apparatus of this embodiment is connected to the cooling block 4 through a cooling block 4 on which the semiconductor wafer 1 is mounted and a cooling pipe 6 partially formed in the cooling block 4. A refrigerator 5 for supplying a refrigerant; a tank 8 for supplying a helium gas as a highly thermally conductive fluid from a supply port 7 to a contact surface between the semiconductor wafer 1 and the cooling block 4 through a flow path provided in the cooling block 4; And a recovery device 11 for recovering the high thermal conductive fluid from the recovery port 10 provided in the cooling block 4 through a return flow path. More specifically, the cooling block 4 is cooled by the refrigerant supplied from the refrigerator 5 through the built-in cooling pipe 6, and the refrigerant is returned to the refrigerator 5 again to form a circulation flow path. In addition, the cooling block 4 includes:
A plurality of supply ports 7 are provided facing the central portion and the outer diameter side of the semiconductor wafer 1. The supply ports 7 are provided with a high thermal conductivity through a flow control valve 9 for controlling the flow rate from a tank 8 to be constant. Fluid is supplied. Further, the cooling block 4 is provided with a plurality of recovery ports 10 which are open on the outer diameter side from the respective supply ports 7 and face the semiconductor wafer 1. Supply port 7
The high thermal conductive fluid flowing out of the cooling block 4 forms a high thermal conductive fluid layer 12 between the cooling block 4 and is recovered by the recovery device 11 through the recovery port 10. Here, the layer referred to as the high thermal conductive fluid layer has a small unevenness due to the surface roughness and warpage of about several μm on the contact surface between the semiconductor wafer 1 and the cooling block 4. This includes a portion in solid contact between them and a minute gap in which a highly thermally conductive fluid exists.

Here, the inspection of the integrated circuit formed on the semiconductor wafer 1 is performed one by one. However, since only the integrated circuit under test generates heat, a flow path corresponding to the integrated circuit 13 under test is formed. Only the provided flow control valve is opened to supply the high heat conductive fluid to the integrated circuit part that is generating heat. Since the supplied high thermal conductive fluid is recovered from the recovery port 10, only the back side of the integrated circuit 13 to be inspected is filled with the high thermal conductive fluid, and the thermal resistance can be partially reduced.

The load of the contact probe pins 2 is applied to the front side of the semiconductor wafer 1. On the other hand, on the back surface of the semiconductor wafer 1, the pressure of the highly thermally conductive fluid acts on the contact surface of the highly thermally conductive fluid. Therefore, the supply pressure of the high thermal conductive fluid is set to be as high as possible so that the average pressure of the high thermal conductive fluid is smaller than the pressure due to the load of the contact probe pin 2 and the pressure of the high thermal conductive fluid at the recovery port 10 is equal to or lower than the atmospheric pressure. , Effective cooling can be performed.

Further, the flow is controlled in synchronization with the movement of the contact probe pins 2 so that the high thermal conductive fluid is supplied only while the contact probe pins 2 apply a load to the semiconductor wafer. Thus, the semiconductor wafer 1 can be brought into close contact with the cooling block 4 and the high thermal conductive fluid can be supplied to the gap between the semiconductor wafer and the cooling block without lowering the thermal conductivity of the high thermal conductive fluid.

Next, a description will be given of an operation method of the embodiment constructed as described above. At the time of inspection, first, the contact probe pins 2 are pressed against a certain integrated circuit on the semiconductor wafer 1. Next, the control valve 9 is opened to supply the high heat conductive fluid. Then, when the high thermal conductive fluid spreads in the gap and the thermal resistance is reduced, power is supplied to the integrated circuit and the inspection is started. When the inspection is completed, first, the supply of the high thermal conductive fluid is stopped, and the contact probe pins 2 are lifted. Next, the contact probe pins 2 are moved to the position of the integrated circuit to be inspected. As a result, first, the integrated circuit that generates heat can always be cooled with high performance. Second, the pressure in the gap between the semiconductor wafer 1 and the cooling block 4 is made smaller than the pressing pressure between the semiconductor wafer 1 and the contact probe pins 2 so that the wafer 1
Can always be adsorbed to the cooling block 4.

FIG. 2 is a front view of the contact surface side of the cooling block 4 in FIG. Providing a high thermal conductive fluid supply port 7 at the center of the area where each integrated circuit contacts and a fluid recovery port 10 at each of the four corners of the area to independently supply and recover the high thermal conductive fluid to each integrated circuit. It is configured to be able to.

FIG. 3 shows a second embodiment of the present invention. In the embodiment shown in FIG. 2, grooves 14 are provided on the surface of the cooling block 4 corresponding to the boundary of each integrated circuit, and adjacent to each other. The high heat conductive fluid recovery ports 10 are connected to each other. As a result, first, the fluid pressure near the recovery port for recovering the fluid can be made uniform in the direction of the peripheral portion of each integrated circuit.
Next, the pressure in the area outside the integrated circuit under load can be reliably reduced to a level lower than the recovery pressure of the high thermal conductive fluid, and the temperature is increased by supplying the high thermal conductive fluid only to the integrated circuit that is generating heat. There are effects such as uniformity. Further, since the fluid collecting pressure is made uniform in the groove 14, the number of the fluid collecting ports 10 can be reduced.

FIG. 4 shows a third embodiment of the present invention.
In this embodiment, the grooves 14 between the integrated circuits arranged in the center in one row are removed, and the high thermal conductive fluid supply ports are integrated into one integrated circuit in this one row.
By doing so, the integrated circuits can be divided into groups, and the supply and recovery of the high thermal conductive fluid can be performed for each group, and the number of supply ports for the high thermal conductive fluid and the number of flow control valves can be reduced. Can be.

FIG. 5 shows still another embodiment of the present invention. The cooling block 4 is located below the cooling block 4.
Is provided, and a supply pipe 18 for a highly thermally conductive fluid is formed substantially in the center of the base 16. An O-ring 17 is provided on the surface of the cooling block 4 opposite to the base 16 in order to prevent the highly thermally conductive fluid from leaking from the supply pipe 18. The cooling block 4 is provided with a groove 14 corresponding to the periphery of each integrated circuit as in the embodiment of FIG. 4, and a fluid recovery port 10 is provided at the bottom of the groove 14. A contact probe pin 2 is provided above the cooling block 4 corresponding to the center of the table 16. The cooling block 4 is provided with a plurality of supply ports for the high heat conductive fluid, and the supply ports used can be changed according to the integrated circuit to be inspected. That is, the cooling block 4 is lifted from the table 16 while the wafer 1 is being sucked to the cooling block 4, and the cooling block 4 is moved horizontally so that the integrated circuit to be inspected is located directly below the contact probe pins 2, and the high thermal conductive fluid is removed. The supply port 18 and the supply port 7 are connected to form one flow path. The connection of this flow path is O
Since it is sealed by the ring 17, leakage of the highly thermally conductive fluid to the outside can be prevented. As a result, a supply path of the highly thermally conductive fluid to the integrated circuit to be inspected is secured. As a result, it is possible to supply the highly thermally conductive fluid to the integrated circuit to be inspected without providing the control valve 9 for each integrated circuit. Further, in the present embodiment, the O-ring 17 is disposed between the cooling block 4 and the table 18, but a groove may be provided in the table 18 or the cooling block 4 and the O-ring may be held in the groove. . In this case, there is an effect that the table 4 can be moved more quickly.

FIG. 6 shows a fourth embodiment of the present invention, in which valves 9 are provided below supply ports 7 of the highly heat conductive fluid. After adjusting the position of the cooling block 4 to the position of the integrated circuit to be inspected, the valve controller 19 is pushed up to supply the high thermal conductive fluid to the chip to be inspected. Thereby, the control mechanism of the valve can be simplified.

FIG. 7 shows a method of manufacturing the cooling block 4. The plates 20, 21, 22, and 23 are sequentially bonded to form a cooling block. The high heat conductive fluid supplied from the outside was sent to the fluid supply port 7 from a channel formed by grooves provided in the plates 21 and 22, and the plates 22 and 23, and was recovered from the recovery port 10. Later, plate 20
And are exhausted by a channel formed by a groove provided between the plate 21 and the plate 21. If manufactured in this way,
Even when the number of fluid supply ports and the number of recovery ports increases, the number of plates can be increased to cope with the increase, and the cooling block can be easily configured.

The present invention also provides a wafer probing test apparatus and a semiconductor CVD apparatus without departing from the scope of the present invention.
Applicable to equipment, etching equipment, etc.

[0032]

As described above, according to the present invention, the heating element can be held in close contact with the cooling element in the air, and the contact thermal resistance between the heating element and the cooling element can be reduced to achieve uniform temperature conditions. It is possible to inspect an integrated circuit formed on a semiconductor wafer.

[0033]

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of one embodiment of the present invention.

2 is a view of a contact surface of the cooling block of FIG. 1;

FIG. 3 is a front view of a cooling block according to another embodiment of the present invention.

FIG. 4 is a front view of a cooling block according to another embodiment of the present invention.

FIG. 5 is a perspective view of another embodiment of the present invention.

FIG. 6 is a longitudinal sectional view of another embodiment of the present invention.

FIG. 7 is a view illustrating a method of manufacturing the cooling block in FIG. 1;

FIG. 8 is a longitudinal sectional view of a conventional semiconductor wafer cooling device.

[Explanation of symbols]

1. Heating semiconductor wafer 2. Contact probe pins 3. Probe card 4. Cooling block
5: Refrigerator, 6: Coolant circulation pipe, 7: High thermal conductive fluid supply port, 8: High thermal conductive fluid tank, 9
... High thermal conductive fluid flow control valve, 10 ... High thermal conductive fluid recovery port, 11 ... Fluid recovery device, 12 ... High thermal conductive fluid layer, 13 ... High thermal conductive fluid recovery groove, 14 ... High thermal conductive fluid supply groove, DESCRIPTION OF SYMBOLS 15 ... Integrated circuit, 16 ... Cooling block support stand, 17 ... O-ring, 18 ... High heat conductive fluid supply pipe, 19 ... Valve controller, 20 ... Grooved plate, 2
4: Vacuum exhaust port

Continuation of the front page (72) Inventor Shoichiro Harada 2326 Imai, Ome-shi, Tokyo Hitachi, Ltd. Inside the Device Development Center, Hitachi, Ltd. (56) References JP-A-5-235122 (JP, A) JP-A-2-62731 (JP) , U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F25D 9/00 G01R 31/26 H01L 21/66

Claims (6)

(57) [Claims] 1. A cooling device for a heating element having a cooling element on which a heating element is mounted and cooled through a contact surface with the heating element, wherein a supply of a high thermal conductive fluid to the contact surface of the cooling element. A port, a recovery port for recovering a high thermal conductive fluid flowing from the supply port through a minute gap formed by unevenness of the contact surface between the heating element and the cooling body, and a flow formed in the cooling body at the supply port. Fluid supply means for supplying a high heat conductive fluid through a passage, fluid recovery means for sucking the high heat conductive fluid from the recovery port through another flow path formed in the cooling body, and the heating element A cooling device for a heating element, comprising: a load mechanism for pressing the cooling element; and pressure adjusting means for lowering a supply pressure of the high thermal conductive fluid to the supply port than a load pressure of the heating element. 2. The cooling device for a heating element according to claim 1, wherein said fluid supply means supplies the highly heat conductive fluid when the heating element is under load. 3. The heat-conductive fluid is divided into a plurality of partial areas, and is formed so as to be capable of generating heat for each of the partial areas, and a high heat conductive fluid is provided between a contact surface of the heat-generating element and the cooling body for each of the partial areas. 2. The cooling device for a heating element according to claim 1, further comprising a fluid supply unit that supplies the fluid and a fluid recovery unit that sucks the highly thermally conductive fluid. 3. 4. The heat generation device according to claim 3, wherein the fluid supply means provided for each of the partial regions supplies the high heat conductive fluid only to the partial region that is generating heat in the partial regions. Body cooling device. 5. The cooling device according to claim 1, wherein the heating element is a semiconductor wafer. 6. The cooling body is formed by laminating a plurality of plates having grooves and through holes on the surface.
The cooling device for a heating element according to any one of claims 1 to 5.