JPH11233598A - Wafer cooler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wafer cooler which can be installed in a vacuum passage and shorten a cooling time, by securing a sufficient contact area with a cooling plate. SOLUTION: A chamber 11 is constituted so as to include the entire cooler 10, and constituted by a high airtight structure separated from an outer air apart from a gate valve 7 which can open and close and have a high airtightness. A cooling plate 12 which can move a wafer on an upper plane face is arranged inside the cooler 10, and further a water conveyance pipe 14 for circulating cooling water 13 is buried inside the cooling plate 12 so as to be stretched around, and both the end parts are connected to a not-shown coolant circulator provided outside the chamber 11. A gas outflow pipe 15 is connected to a center of a ceiling part of the chamber 11 towards an upper face of the cooling plate 12, while a gas suction pipe 16 is connected to a center of an upper face of the cooling plate 12. A wafer 6 is closely vacuum-chucked to the cooling plate 12 by gas suction, and after efficient heat absorption, heat is dissipated outside the device by the coolant 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for cooling a semiconductor wafer in a vacuum transfer path in a semiconductor chip manufacturing process, particularly in a manufacturing process using a cluster tool.

[0002]

2. Description of the Related Art Conventionally, the most common method of forming a circuit in a semiconductor chip manufacturing process is a method of repeatedly performing various heat treatments such as film formation, etching, and impurity diffusion on the surface of a circular flat semiconductor wafer. . According to this method, high-temperature heating is repeatedly applied to the wafer, and the temperature of the wafer itself reaches a considerably high temperature, so that a temperature at which the wafer can be set in a resin wafer transport container,
Alternatively, a step of cooling to a temperature at which subsequent processing can be performed is required.

FIG. 5 is a top view showing an example of a cluster tool 1 used as an apparatus for performing the above-mentioned wafer surface treatment. In this figure, process chambers 2a, 2b, and 2c, which are partition chambers (hereinafter referred to as chambers) for performing each wafer processing, and two cassette modules for transferring a wafer before processing and a wafer after processing to the outside, respectively. Chambers 3a and 3b are installed so as to surround a wafer transfer area 5 where a wafer transfer robot 4 is installed at the center.

Here, in the wafer transfer area 5 in the cluster tool 1 and the work areas such as the process chambers 2a, 2b and 2c, contamination (degeneration) of the wafer surface by gas is caused.
It is in a vacuum state for the purpose of preventing dust and dust, and has a sealed structure isolated from the outside air.

A wafer cooling method conventionally used in a wafer processing apparatus typified by such a cluster tool 1 includes, as shown in FIG. 1A, a surface mounted on a metal gantry installed in a vacuum path. A method of placing a heat-treated high-temperature wafer 6 and leaving it to dissipate heat, and setting one of the process chambers as a cooler chamber 8 separated by a highly airtight gate valve 7 to remove the surface-heat-treated high-temperature wafer 6 Two methods of cooling by transferring and internally circulating and contacting the cooling gas 9 have been practiced as general methods.

[0006]

However, in the former method of leaving on a gantry in a vacuum, there is no gas serving as a heat radiating medium around the wafer, and heat is radiated by infrared radiation and heat radiation from the metal gantry comes into contact. However, there is a problem that the cooling capacity is not sufficient due to heat diffusion due to heat conduction from the periphery of the wafer, and unevenness occurs due to a partial cooling difference on the wafer surface.

[0007] Further, even in the latter method of heat exchange using only the cooling gas 9, the cooling capacity is not sufficient, and as a result, a long cooling time is required, which causes a reduction in the efficiency of the entire wafer processing process.

Further, the wafer after the surface heat treatment is slightly deformed in a curved manner so as to swell downward. Therefore, when the wafer is placed on a plane, it is placed by almost one point of contact. This has resulted in lowering and inhomogeneity due to local cooling differences.

Accordingly, the present invention has been made in view of the above-mentioned problems, and it has been found that a sufficient contact area with a cooling plate can be ensured even when a wafer is curved and deformed to expand downward by surface heat treatment.
It is another object of the present invention to provide a wafer cooling apparatus which can reduce a wafer cooling time by providing an efficient heat exchange means, and thereby improve the efficiency of the entire wafer processing process.

[0010]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and is constituted as follows. First, the present invention provides a cooling plate capable of absorbing heat by mounting a wafer, a wafer suction means for suctioning the wafer on the cooling plate,
An external heat radiating means for releasing the heat absorbed by the cooling plate to the outside of the apparatus is provided in an airtight space isolated from outside air.

As a result, even when the wafer is curved and deformed so as to expand downward due to each surface treatment, a sufficient contact area with the cooling plate can be ensured as compared with the conventional case, so that heat can be efficiently absorbed and the time required for cooling is reduced. Is shortened.

Further, for example, the closed space is configured to be a chamber having a sealable opening / closing mechanism. Further, for example, as set forth in claim 3, the wafer suction means connects an outflow pipe to the chamber wall surface to send gas into the chamber, and connects a suction pipe to the upper surface of the cooling plate to supply the gas. A gas suction means for sucking gas and a ventilation groove formed on the cooling plate to guide gas from the periphery of the wafer to a suction pipe connected to the upper surface of the cooling plate.

Further, for example, the gas is used as a cooling gas for cooling the wafer and the cooling plate. Further, for example, the wafer suction means is configured to be an electrostatic chuck.

Further, the cooling means for cooling the cooling plate is configured to perform cooling by arranging a conduit inside the cooling plate and causing a cooling fluid to flow in and out.

Further, for example, the means for cooling the cooling plate is a heat pipe, one end of which is disposed inside the cooling plate, and the other end of which is provided in a gas outside the chamber. It is configured to provide a heat dissipation mechanism including a heat dissipation fin and a heat dissipation fan.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. First, FIG. 1 is a side sectional view for explaining an embodiment of the first embodiment of the present invention. In this figure, a chamber 11 having a configuration including the entire wafer cooling device 10 is shown.
Has a highly airtight structure that is openable and closable and is isolated from the outside air via a gate valve 7 as an opening and closing mechanism having high airtightness. A cooling plate 12 having an upper surface on which a wafer can be placed is installed therein, and a water guide pipe 14 as a conduit for circulating cooling water 13 as a cooling fluid is provided inside the cooling plate 12. Both ends are connected to a cooling water circulation device (not shown) provided outside the chamber 11 as an airtight space.

At the center of the ceiling of the wall surface of the chamber 11, a gas outlet pipe 15 as an outlet pipe constituting gas outlet means is connected toward the upper surface of the cooling plate 12, while at the center of the upper surface of the cooling plate 12. A gas suction pipe 16 as a suction pipe constituting a gas suction means is connected upward.

The other end of each of the gas pipes 15 and 16 is connected to a gas introduction device constituting gas outflow means (not shown) and a gas suction apparatus constituting gas suction means (not shown) so that a constant amount of gas is constantly replaced. As a result, the pressure inside the chamber 11 is kept constant.

As shown in the enlarged circle in the figure, a ventilation groove 17 having a sufficiently small cross-sectional area of the passage is formed on the upper surface of the cooling plate 12 from the outer periphery of the upper surface of the cooling plate 12 to the center of the gas suction pipe 1.
In this embodiment, the wafer mounting surface of the cooling plate 12 is subjected to a tuffram treatment for performing a fluorine treatment on the alumite treatment. In addition, the flat portion is mirror-finished in order to make it more closely contact with the wafer 6.

In this embodiment, the wafer suction means is constituted by the ventilation groove 17 and the gas suction pipe 16. this is,
The same applies to a second embodiment described later. In this embodiment, the water pipe 14 constitutes a heat radiation means outside the apparatus.

Hereinafter, the operation of the thus configured wafer cooling apparatus 10 will be described. First, the gate valve 7 is opened and the wafer 6 subjected to the surface heat treatment is placed on the cooling plate 12 in the chamber 11 in a vacuum state (by the transfer means such as the wafer transfer robot 4 described above). Since the wafer 6 after the surface heat treatment is curved and deformed so as to swell downward, when the wafer 6 is first placed on the cooling plate 12, the wafer 6 is placed by almost one point of contact. Then, the gas outlet pipe 1 is closed in the closed chamber 11 by closing the gate valve 7.
From 5, the wafer 18 is filled with the gas 18 for both wafer suction and wafer cooling, and at the same time, the gas suction pipe 16 on the upper surface of the cooling plate 12.
, The suction of the gas 18 is performed in parallel.

Here, when the gas 18 flows through the ventilation groove 17 from the intake end of the ventilation groove 17 around the upper surface of the cooling plate toward the gas suction pipe 16, the gap between the lower surface of the wafer and the upper surface of the cooling plate 12 is negative. Pressure is applied, and a pressure difference is generated between the pressure and the positive gas pressure applied to the upper surface of the wafer on the opposite side.
Is fixed on the upper surface of the cooling plate 12 in such a manner as to be adsorbed. Further, when the gas 18 comes into contact with both surfaces of the upper and lower surfaces of the wafer, heat radiation of the wafer 6 is performed at the same time.

FIG. 2 shows the ventilation groove 1 viewed from the upper surface of the cooling plate 12.
7 shows an example of an engraving pattern No. 7; According to the figure, the suction ends of the ventilation grooves 17 are located at eight equal intervals on the circumference of the cooling plate 12, and are straightly carved therefrom toward the gas suction pipe 16 connected to the center. Cooling plate 1
A circular ventilation groove 17 concentric with 2 is formed twice in the radial direction. With such an engraved pattern, the suction force generated by the gas 18 flowing into the ventilation groove 17 can be evenly applied to the entire contact surface of the wafer 6, and at the same time, the gas 18 is circulated. Thus, the cooling of the wafer 6 can be performed evenly over the entire surface of the wafer 6. The engraving pattern is not limited to the pattern shown in FIG. 2, and other patterns can be set as long as the above-described uniformity of suction and cooling is taken into consideration. For example, a spiral pattern, a mesh pattern, or a simple radial pattern may be used.

The composition of the gas 18 used for adsorbing and cooling the wafer 6 is an inert gas to prevent contamination of the surface of the wafer 6, and an argon gas is generally used because of its large heat capacity. However, another gas may be used as long as an equivalent function is obtained. For example, the inert gas may be helium gas or the like,
Alternatively, other than the inert gas, carbon dioxide gas, nitrogen gas, or the like may be used.

By the above-described suction action and the above-described mirror finishing, even a wafer 6 which is curved and deformed in a downwardly swelling manner can be brought into close contact with a mounting surface in a wide area, and a metal wafer cooling having a large heat capacity can be cooled. Efficient heat absorption from the plate 12 is performed.

The cooling water 13 flows into, circulates, and discharges the cooling water conduit 14 buried inside the cooling plate 12 as a radiating means of the cooling plate 12, thereby releasing the heat absorbed from the wafer 6 to the outside of the apparatus. As a result, the heat absorbing effect of the cooling plate 12 up to the target temperature is maintained and continued.

The cooling fluid flowing into the conduit is not limited to water, but may be another fluid having high heat radiation. For example, Freon, liquid nitrogen, liquid helium, and the like can be given. Further, the cooling fluid is not limited to a liquid, but may be a gas.

The installation location of the gas outlet pipe 15 is not limited to the ceiling just above the wafer mounting surface as long as it is a wall surface of the chamber, and may be shifted to another ceiling.
Alternatively, it may be provided on a wall surface other than the ceiling, for example, on a side wall.
However, the direction in which the gas flows out is desirably provided on the wafer mounting surface.

Further, the installation location of the gas suction pipe 16 is not limited to the structure provided at the center of the cooling plate 12, but may be installed at a position deviated from the center to the periphery. Further, the structure is not limited to the structure in which the cooling plate 12 penetrates the inside from below and is connected to the wafer mounting surface. If the gas can be sucked from the ventilation groove 17 provided in the wafer mounting surface, other structures may be used. May be.
For example, the connection may be made from the side instead of the inside of the cooling plate.

The above points are the same for the second embodiment described later. Next, FIG. 3 is a side sectional view for explaining a second embodiment of the present invention. In this figure, the first
The difference from the embodiment is that the heat pipe 19 is used as an external heat radiation means for radiating the heat absorbed by the cooling plate 12 to the outside, and the radiation fins 20 and the heat radiation The point is that a heat radiating mechanism including the fan 21 is provided.

[0031] A capillary pipe wetting material made of glass fiber or a thin net-like copper wire is applied to the inside of a metallic pipe having high heat conductivity, and the inside of the pipe is depressurized. It is a device that performs heat transfer by exchanging heat and latent heat of vaporization.It is not only capable of efficient heat dissipation, but also requires the installation of a special circulating device only by providing heat exchange means with a relatively simple structure. Since there is no cooling device 10, the whole cooling device 10 can be simplified in structure, and there is an advantage that the maintainability is improved.

If the heat radiation of the heat pipe 19 is sufficient, the heat pipe may be provided alone without providing the heat radiation fins 20 and the heat radiation fan 21. Alternatively, only the heat radiating fins may be provided on the heat pipe, or only the heat radiating fan may be provided on the heat pipe in combination. Further, the water radiating fins and the heat radiating fan of the present embodiment may be provided in the water pipe 14 of the first embodiment.

The heat exchanging means of the radiating fins 20 and the radiating fan 21 of the present embodiment is a heat pipe 19 extending into a gas capable of performing air cooling outside the cluster tool 1.
Need to be installed on top.

FIG. 4 is a side sectional view for explaining a third embodiment of the present invention. In this figure, the difference from the second embodiment is that an electrostatic chuck 22 is used as a wafer suction means for sucking the wafer 6 on the upper surface of the cooling plate 12. The electrostatic chuck 22 is connected to a control device (not shown) via a hermetic terminal 23 which is a terminal having airtightness to a gas outside the cluster tool 1, and
Is performed. As a result, the chamber 1 is compared with the case where the wafer suction means by gas suction is used.
Since airtightness is not required for the device 1 itself, that is, since a gate valve is not required, there is an advantage that a wafer can be suctioned with a simpler configuration and maintenance performance is improved.

Since the chamber itself does not require airtightness,
It is also possible to provide it in a vacuum path outside the chamber, which is an airtight space (relative to the outside air). Further, compared with the wafer suction means by gas suction, the suction of the wafer 6 closely contacted over a wide range of the cooling plate can be performed more reliably, so that a high heat absorption efficiency can be obtained.

The electrostatic chuck mechanism may be cooled by gas as in the first embodiment. Thereby, a higher cooling effect can be obtained. However, in this case, it is necessary to provide in a chamber having a gate valve.

Incidentally, the mirror finishing of the upper surface of the cooling plate may be omitted if necessary if sufficient adhesion is obtained. Similarly,
Tough ramming of the surface may be omitted if necessary.

[0038]

As described above, according to the present invention, in a cluster tool, it is possible to provide a wafer cooling apparatus capable of performing efficient cooling in a short time with less contamination of a semiconductor wafer after surface heat treatment. In addition, the efficiency of the entire semiconductor chip manufacturing process can be improved.

[Brief description of the drawings]

FIG. 1 is a side sectional view illustrating an embodiment of a first embodiment of the present invention.

FIG. 2 shows an example of an engraving pattern of a ventilation groove viewed from the upper surface of a cooling plate.

FIG. 3 is a side sectional view for explaining a second embodiment of the present invention.

FIG. 4 is a side sectional view illustrating a third embodiment of the present invention.

FIG. 5 is a top view showing an example of a cluster tool which is an apparatus for performing a wafer surface treatment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cluster tool 2a, b, c Process chamber 3a, b Cassette module chamber 4 Wafer transfer robot 5 Wafer transfer area 6 Wafer 7 Gate valve 8 Cooler chamber 9 Cooling gas 10 Wafer cooling device 11 Chamber 12 Cooling plate 13 Cooling water 14 Water pipe Reference Signs List 15 gas outflow pipe 16 gas suction pipe 17 ventilation groove 18 gas 19 heat pipe 20 heat radiation fin 21 heat radiation fan 22 electrostatic chuck 23 hermetic terminal A wafer left in vacuum path

Claims (7)

[Claims] 1. A cooling plate capable of absorbing heat by mounting a wafer, a wafer suction means for sucking the wafer on the cooling plate, and a device for radiating heat absorbed by the cooling plate to the outside of the apparatus. A wafer cooling device, characterized in that the external device heat dissipating means and are arranged in an airtight space isolated from outside air. 2. The wafer cooling apparatus according to claim 1, wherein said airtight space is a chamber having an openable and closable mechanism. 3. A gas outflow means, wherein the wafer suction means connects an outflow pipe to the chamber wall surface and sends gas into the chamber, and a gas suction means in which a suction pipe is connected to an upper surface of the cooling plate to suck the gas. 3. The wafer according to claim 2, further comprising: means, and a ventilation groove formed on the cooling plate to guide the gas from the periphery of the wafer to a suction pipe connected to the upper surface of the cooling plate. Cooling system. 4. The wafer cooling apparatus according to claim 2, wherein said gas is also used as a cooling gas for cooling the wafer. 5. The wafer cooling device according to claim 1, wherein said wafer suction means is an electrostatic chuck. 6. A wafer cooling apparatus according to claim 1, wherein said external heat radiating means performs cooling by flowing a cooling fluid into and out of a conduit embedded in said cooling plate. 7. The heat radiating means outside the apparatus is a heat pipe, one end of which is buried inside the cooling plate, and the other end of which is provided with a heat radiating mechanism including a radiating fin and a radiating fan in a gas outside the chamber. 2. The wafer cooling apparatus according to claim 1, wherein the apparatus has a configuration.