JPH09232266A - Cleaner of semiconductor wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cleaner of a semiconductor wafer capable of preventing contamination for a substance to be cleaned or an inner wall of a high pressure container. SOLUTION: An upper lid 22 has such a shape that a box is fumed over and is provided with an injection port 23 in an upper center, and a stage 21 is covered forming a clearance 26. A quantity of supercritical fluid injected from the injection port 23 is balanced with a quantity of supercritical fluid discharged outside a cleaning bath from the clearance 26, whereby the inside of the cleaning bath is held in a supercritical state without airtightly closing the cleaning bath with a seal material. Accordingly, a wafer 24 or an inner wall of the upper lid 22 is not contaminated by the seal material. Further, a contaminant extracted into the supercritical fluid is speedily discharged outside the cleaning bath and the wafer 24 or an inner wall of the upper lid 22 is not contaminated again.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor wafer cleaning apparatus using a supercritical liquid.

[0002]

2. Description of the Related Art A supercritical liquid refers to a state having an intermediate property between liquid and gas obtained at a critical pressure Pc or higher and a critical temperature Tc or higher as shown in the phase diagram of FIG. . The supercritical liquid has various properties suitable for the field of precision cleaning.

That is, a high dissolving power is effective for cleaning organic components, a high diffusion coefficient enables uniform cleaning in a short time, and a viscosity close to that of gas is suitable for cleaning a fine portion. Further, when the pressure is lowered to the critical pressure or lower, it becomes a gas, so that there is an advantage that only the pressure reduction is required for the drying process.

CO ₂ is often used as the supercritical liquid. Since CO ₂ has a critical pressure of 73 atm and a critical temperature of 31.1 ° C., a supercritical state can be obtained relatively easily. Further, since CO ₂ itself is non-toxic, industrially safe use is possible. Other supercritical liquids include N ₂ (critical pressure = 33.5 atm, critical temperature = -147 ° C.) and CClF ₃ (critical pressure = 39 atm,
Critical temperature = 28.8 ° C).

Conventionally, as a cleaning device for cleaning using the above-mentioned supercritical liquid, there is one as shown in FIG. This cleaning device includes a CO ₂ cylinder 1 serving as a gas supply source, a pressure adjusting valve A, a pressure adjusting valve B, a cleaning tank 2, a separation tank 3, a filter 4, a pressure pump 5, a heater 6, a cooler 7, and a cylinder. The structure is generally configured by connecting the for-use valve 8, the replenishment valve 9 and the exhaust valve 10 with a pressure resistant pipe. The lid 13 of the cleaning tank 2 is sealed with a sealing material 14.

The operation of the cleaning apparatus having the above structure will be briefly described below. First, the wafer 1 that is the object to be cleaned
1 is put in the washing tank 2 and sealed with a lid 13. Then, the cylinder valve 8 and the refill valve 9 are opened. Then, the CO ₂ gas in the cylinder 1 passes through the filter 4, is liquefied by the cooler 7, and is pressurized to a pressure higher than the critical pressure by the pressure feed pump 5, and further heated to a temperature higher than the critical temperature by the heater 6. The temperature is raised to a supercritical state, and the supercritical state is supplied to the cleaning tank 2. At that time, the inside of the cleaning tank 2 is maintained at a pressure equal to or higher than the critical pressure by the pressure adjusting valve A. On the other hand, the pressure inside the separation layer 3 is maintained at a pressure lower than the critical pressure by the pressure control valve B.

By the above operation, the flow of the fluid becomes as shown by the arrow, and the contaminants on the object to be cleaned 11 are dissolved in the supercritical liquid in the cleaning tank 2. Further, the supercritical liquid in which the pollutant is melted becomes a gas below the critical pressure in the separation tank 3 and becomes a gas, which is separated from the pollutant. The pollutants thus separated are deposited on the bottom of the separation tank 3, and CO ₂ is exhausted to the atmosphere or recycled. The contaminants deposited in the separation tank 3 are taken out by opening the valve 12.

As another cleaning device using a supercritical liquid, a cleaning device having a horizontal cleaning tank and a lid and an opening / closing part for the lid (Japanese Patent Laid-Open No. 4-17333) or a supercritical state is used. A cleaning device in which the surroundings of the extraction chamber are surrounded by a separation chamber, the extraction chamber and the separation chamber are integrally formed, and the inflow and outflow of the supercritical fluid to and from the extraction chamber are performed from the same direction through a lid (JP-A-4- 39499).

[0009]

However, the conventional cleaning device using the above-mentioned supercritical liquid has the following problems. (1) The cleaning tank 2 and the extraction chamber in which the object to be cleaned is placed are high-pressure vessels, and the sealing material 14 is required to enhance the airtightness of the lid. When the sealing material 14 is formed of resin, the sealing material 14 is easily deteriorated by being exposed to a supercritical liquid having a high oil / fat extraction capability, and the operating frequency of the device is increased due to an increase in the replacement frequency of the sealing material 14. descend. Furthermore, the extracted oil and fat component of the sealing material 14 causes contamination of the object to be cleaned and the side wall of the high-pressure container. On the other hand, the metal sealing material cannot be used repeatedly, and thus needs to be replaced frequently, which results in a significant increase in running cost.

(2) In the cleaning device shown in FIG. 6 or in the cleaning device in which the extraction chamber and the separation chamber are integrally formed, the supercritical liquid injection port and the exhaust port are provided on the same surface. The structure is such that turbulent flow is likely to occur. For this reason, re-adhesion of contaminants to the object to be cleaned and the side wall of the high-pressure container and particles are likely to occur, and the cleaning effect is reduced.

(3) In a cleaning device in which the cleaning tank is horizontal and has a lid and an opening / closing portion, the opening / closing portion comes into contact with the supercritical liquid, so that contamination or deterioration occurs.

All of these problems lead to a decrease in operating time due to replacement of the sealing material and cleaning of the side wall of the high-pressure container,
This hinders automation of the cleaning device.

Therefore, an object of the present invention is to prevent deterioration of the sealing material and prevent contamination of the object to be cleaned and the side wall of the high-pressure container, thereby facilitating automation, and a high-throughput semiconductor wafer cleaning apparatus. To provide.

[0014]

In order to achieve the above object, the invention according to claim 1 has a stage on which a wafer carrier on which a wafer to be cleaned is mounted is mounted, a box-like shape, and an upper part. An inlet for the cleaning substance is provided on the upper wall to form a gap at the lower end of the wall to cover the stage, and a cleaning substance heated to a supercritical state by heating is supplied from the inlet of the upper lid. A cleaning substance supply means for cleaning the stage, and a cleaning substance discharge means for discharging the cleaning substance from a gap formed between the upper cover and the stage when the stage is covered with the upper cover,
The apparatus is characterized in that the apparatus further comprises discharge amount adjusting means for adjusting the amount of the cleaning material discharged by the cleaning material discharging means to keep the pressure of the cleaning material in the wall at a constant pressure equal to or higher than the critical pressure.

In the above structure, when the stage on which the wafer carrier carrying the wafer to be cleaned is placed is covered by the upper lid, a gap is formed between the lower end of the wall of the upper lid and the upper surface of the stage. Then, while the cleaning substance in the supercritical state is supplied from the inlet of the upper lid by the cleaning substance supplying means, the cleaning substance is discharged from the gap by the cleaning substance discharging means. At that time, the discharge amount adjusting means adjusts the discharge amount of the cleaning substance so that the pressure of the cleaning substance in the wall is maintained at a constant pressure equal to or higher than the critical pressure. In this way, the wafer to be cleaned is cleaned by the cleaning substance in a supercritical state that flows from the inlet at the upper part of the upper lid to the gap at the lower part and is discharged quickly from the gap.

According to a second aspect of the present invention, in the semiconductor wafer cleaning apparatus of the first aspect of the present invention, the stage has an outer peripheral portion extending to the periphery, and the upper lid is adjacent to the periphery. It has a chamber formed and an outlet for the cleaning substance at the top, and when the stage is covered with an upper lid, it has a sealing means for sealing between the outer wall of the upper lid and the outer peripheral portion of the stage. , The cleaning substance discharging means,
By discharging the cleaning substance in the chamber from the discharge port of the upper lid, the cleaning substance in the wall is discharged from the gap, and the discharge amount adjusting means is discharged by the cleaning substance discharging means. By adjusting the amount of the cleaning substance, the pressure of the cleaning substance inside the wall is maintained at a constant pressure above the critical pressure, while the pressure of the cleaning substance in the chamber outside the wall is maintained at a constant pressure lower than the critical pressure. It is characterized by being.

In the above structure, when the stage on which the wafer carrier carrying the wafer to be cleaned is placed is covered by the upper lid, the outer wall of the upper lid and the outer peripheral portion of the stage are sealed by the sealing means. On the other hand, a gap is formed between the lower end of the wall of the upper lid and the upper surface of the stage. In this way, a cleaning chamber inside the wall of the upper lid and a separation chamber outside the wall are formed. Then, the cleaning substance in the supercritical state is injected into the cleaning chamber from the inlet of the upper lid by the cleaning substance supply means, while the cleaning substance in the separation chamber is discharged from the outlet of the upper cover by the cleaning substance discharge means. At that time, the discharge amount of the cleaning substance is adjusted by the discharge amount adjusting means to keep the pressure of the cleaning substance in the cleaning chamber at a constant pressure equal to or higher than the critical pressure, while the pressure of the cleaning substance in the separation chamber is adjusted to the critical pressure. Maintained at a lower constant pressure. In this way, the wafer to be cleaned is cleaned by the cleaning substance in a supercritical state that flows in order from the upper inlet of the cleaning chamber toward the lower clearance and is quickly discharged from the clearance. Further, the cleaning substance discharged from the gap into the separation chamber becomes a gas state, and the contaminant is promptly separated.

According to a third aspect of the present invention, in the semiconductor wafer cleaning apparatus according to the first aspect of the invention, at least one of the lower end of the wall of the upper lid and the upper face of the stage opens or closes the gap. It is characterized in that it is movable and that the interval of the gap formed when the stage is covered by the upper cover is adjustable.

In the above structure, when the stage is covered with the upper lid, at least one of the lower end of the wall of the upper lid and the upper surface of the stage which forms the gap is moved to optimally adjust the gap interval. To be done. In this way, the cleaning substance pressure inside the wall of the upper lid and the cleaning substance pressure in the chamber outside the wall are adjusted to be more optimal.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the embodiments shown in the drawings. FIG. 1 is a diagram showing a basic configuration of a cleaning tank in the semiconductor wafer cleaning apparatus of this embodiment. The main cleaning tank is roughly composed of a stage 21 on which a wafer carrier 25 having a plurality of wafers 24 to be cleaned is mounted and an upper lid 22 having a box-like shape and covering the stage 21. The upper lid 22 is provided with an injection port 23 for injecting a cleaning substance (supercritical fluid) in a supercritical state at the center of the upper part, and forms a gap 26 to cover the stage 21. Then, while the supercritical fluid pressurized and heated to the above supercritical state is injected from the injection port 23, the stage 21 and the upper lid 2
The supercritical fluid is exhausted from the gap 26 with respect to 2. At that time, by balancing the amount of the supercritical fluid discharged from the gap 26 to the outside of the cleaning tank and the amount of the supercritical fluid injected from the inlet 23, the cleaning tank is not sealed with a sealing material, Can be kept in a supercritical state. In this way, a steady state is formed in which the supercritical fluid is exhausted from the gap 26 between the stage 21 and the upper lid 22 while maintaining the atmosphere around the wafer to be cleaned 24 in the supercritical state.

As a result, in the present embodiment, the cleaning tank does not need a sealing material, and the deterioration of the sealing material and the contamination of the wafer 24 to be cleaned by the sealing material can be eliminated. Further, the contaminants extracted from the surface of the wafer to be cleaned 24 into the supercritical fluid are promptly discharged outside the cleaning tank by the flow 27 of the supercritical fluid. Therefore, the wafer to be cleaned 2
It is possible to prevent the contaminants in the supercritical fluid from adhering to the inner wall of the upper lid 4 and the upper lid 22.

When a separation tank is provided adjacent to the side where the supercritical fluid is exhausted from the gap 26, the supercritical fluid is forcibly sucked from the separation tank by a circulation pump or the like to wash the supercritical fluid. Increase the pressure difference between the tank and the separation tank.

A specific example of a semiconductor wafer cleaning apparatus using the cleaning tank having the above-described basic structure will be described below. FIG. 2 is a fluid circuit diagram of the semiconductor wafer cleaning apparatus according to the present embodiment. The present semiconductor wafer cleaning apparatus uses a cylinder 31, which supplies CO ₂ as a supercritical fluid,
Pressure regulating valve 32, exhaust valve 33, high-pressure container 34 having a double structure in which a cleaning tank and a separation tank are integrated, a filter 35, a pressure pump 36, a heater 37, a cooler 38, a cylinder valve 39.
The replenishment valve 40 is connected by a pressure resistant tube.

As shown in FIG. 3, the high-pressure container 34 has the following structure.
A cleaning chamber 51 having the same basic structure as the cleaning tank shown in FIG.
And a separation chamber 52 integrally provided around the cleaning chamber 51
It has a double structure consisting of In addition, the high pressure container 34
From a structural point of view, is composed of a fixed upper lid 53 having an injection pipe 54 and a discharge pipe 55, and a vertically movable stage 56.

The upper lid 53 has a shape like that of a shallow pot, an injection pipe 54 extending outward is provided at the center of the upper portion, and a discharge pipe is provided around the injection pipe 54. 55 is provided. In addition, the injection pipe 54 and the discharge pipe 5
An annular inner wall 57 extending inward is formed between the inner wall 57 and the inner wall 57 of the cleaning chamber 5.
1 and the surrounding separation chamber 52 are partitioned. Further, an outer wall 58 forming an outer shell of the upper lid 53 separates the separation chamber 52 from the external environment.

The stage 56 is mounted on an elevating table 59 and has a stage body 61 on which a wafer carrier 60 is mounted.
An outer peripheral portion 62 that extends from the stage body 61 to the outer periphery and forms the bottom of the separation chamber 52. Then, the stage 56 is raised to a predetermined position by the lift table 59, and the upper lid 53
1 is closed, a gap 63 is formed between the lower end of the inner wall 57 of the upper lid 53 and the outermost peripheral portion of the stage body 61, while the outer wall 58 of the upper lid 53 is closed, as in the case of the cleaning tank shown in FIG. The lower end and the outer edge of the outer peripheral portion 62 of the stage 56 are in close contact with each other via a sealing material 64. In this way, when the upper lid 53 is closed, a double-structured high-pressure container 34 having a cleaning chamber 51 having the same structure as the cleaning tank shown in FIG. 1 and a separation chamber 52 around the cleaning chamber 51 is formed.

Here, the injection pipe 5 into which the supercritical fluid is injected
4 is provided in the upper part of the cleaning chamber 51, while the discharge pipe 55 for discharging the supercritical fluid in which the contaminants are dissolved is provided in the separation chamber 52.
Is provided on the upper side of the injection tube 54, and its diameter is set larger than the diameter of the injection tube 54. Then, in order to reduce the pressure in the separation chamber 52, the circulation pump 41 (see FIG. 2) is forcibly sucked. Therefore, the supercritical fluid injected from the injection pipe 54 flows vertically in the cleaning chamber 51 toward the gap 63 at the lower end of the inner wall 57 as shown by arrows (a) and (b), and the supercritical fluid in the wafer carrier 60 is discharged. It flows in an orderly manner parallel to the surface of the wafer 65.

The outer peripheral portion 62 of the stage 56 is
The upper surface of is formed lower than the upper surface of the stage body 61 to form an annular groove, and the contaminants separated from the supercritical fluid in the separation chamber 52 are accumulated. The stage 56 can be detached from the lift table 59 to facilitate cleaning of the groove. Further, for safety, when the stage 56 is in close contact with the outer wall 58 of the upper lid 53, the stage 66 is locked by the metal fitting 66.

The semiconductor wafer cleaning apparatus having the above structure cleans the wafer to be cleaned by the following steps. 2 and 3, first, the metal fitting 66 is removed, the stage 56 is lowered, and the wafer carrier 60 containing the wafer to be cleaned 65 is set on the stage body 61 of the stage 56. Then, the stage 56 is raised to close the cleaning chamber 51 and the separation chamber 52, and the metal fitting 66 is locked so that the state shown in FIG. 3 is obtained.

Subsequently, the cylinder valve 39 and the replenishment valve 40 are opened, and the circulation pump 41 is driven to enter the supercritical state via the filter 35, the cooler 38, the pressure pump 36 and the heater 37. CO ₂ injection pipe 5
4 into the cleaning chamber 51. At that time, by utilizing the differential pressure between the cleaning chamber 51 and the separation chamber 52 caused by the presence of the inner wall 57, the inside of the cleaning chamber 51 is kept at a constant pressure equal to or higher than the critical pressure, while the inside of the separation chamber 52 is at the critical pressure. The opening degree of the pressure adjusting valve 32 is adjusted so that the lower constant pressure is maintained.
Thus, the cleaning of the wafer to be cleaned 65 is started.

Then, when the supercritical fluid CO _{2 in} which the organic pollutants are dissolved reaches the separation chamber 52 through the gap 63 at the lower end of the inner wall 57 of the cleaning chamber 51 and becomes a pressure lower than the supercritical pressure, The pollutants are separated from the gaseous CO ₂ and accumulated in the groove formed on the outer peripheral portion 62 of the stage 56. When the cleaning is finished, the circulation pump 41 is stopped, the cylinder valve 39 and the replenishment valve 40 are closed, and the exhaust valve 33 is opened to bring the cleaning chamber 51 and the separation chamber 52 to the atmospheric pressure.

Here, the cleaning chamber 51 has a height / diameter so that the supercritical fluid CO ₂ injected from the injection pipe 54 flows in parallel to the surface of the wafer to be cleaned 65 (that is, from top to bottom). The ratio is set to be "1" or more. Also,
The injection pipe 54 is provided at the center of the cross section of the cleaning chamber 51 so that the turbulent flow of the supercritical fluid CO ₂ does not occur in the cleaning chamber 51.

As described above, the semiconductor wafer cleaning apparatus according to the present embodiment has a high pressure which is roughly constituted by the stage 56 on which the wafer carrier 60 is placed and the upper lid 53 which covers the stage 56 with the gap 63. Having a container 34,
When the stage 56 is sealed with the upper lid 53, the cleaning chamber 51 having the same basic structure as the cleaning tank shown in FIG. 1 and the separation chamber 52 integrally provided around the cleaning chamber 51 are formed. An injection pipe 54 is provided at the center of the upper part of the cleaning chamber 51, and a discharge pipe 55 is provided at the upper part of the separation chamber.

The diameter of the discharge pipe 55 is set to the injection pipe 5
The diameter is set larger than the diameter of No. 4, and the inside of the separation chamber 52 is forcibly sucked by the circulation pump 41. As a result, by adjusting the opening degree of the pressure adjusting valve 32, the supercritical fluid pressure in the separation chamber 52 is reduced, and the inside of the cleaning chamber 51 is maintained at a constant pressure equal to or higher than the critical pressure, while the separation chamber 52 is kept. The inside is kept at a constant pressure below the critical pressure.

Therefore, the supercritical fluid CO ₂ injected from the upper portion of the cleaning chamber 51 flows orderly along the surface of the wafer to be cleaned 65 toward the gap 63 provided in the lower portion of the cleaning chamber 51, and quickly. It is discharged from the gap 63 into the separation chamber 62. That is, according to the semiconductor wafer cleaning apparatus of the present embodiment, a sealing material for sealing the space between the cleaning chamber 51 and the separation chamber 52 is unnecessary, and deterioration of the sealing material and contamination of the wafer to be cleaned 65 by the sealing material are eliminated. It can be prevented. Further, since the turbulent flow of the supercritical fluid CO ₂ does not occur, recontamination of the wafer to be cleaned 65 and the inner wall of the upper lid 53 can be prevented.

In FIG. 4, the size of the gap between the stage on which the wafer carrier is placed and the inner wall of the cleaning chamber is controlled,
FIG. 6 is a cross-sectional view of a stage portion in a semiconductor wafer cleaning apparatus that can finely adjust the differential pressure between the cleaning chamber 51 and the separation chamber 52. The stage 72 is a circular base 73 mounted on the lift table 71.
An outer peripheral portion 74 which is provided on the outer periphery of the base portion 73 and forms the bottom of the separation chamber, and the stage main body 7 mounted on the base portion 73.
And 5. The upper surface of the outer peripheral portion 74 is formed lower than the upper surface of the base portion 73 to form an annular groove, and the contaminants separated from the supercritical fluid are accumulated in the separation chamber. The stage main body 75 has a bottomed cylindrical shape, and the wafer carrier 76 is placed on the upper surface thereof, while the inner wall of the cylindrical portion has a male screw formed on the stepped portion of the base portion 73. A female screw 78 that is screwed into 77 is formed.

Therefore, when the stage main body 75 screwed to the base 73 is rotated by the rotation driving unit (not shown), the stage main body 75 moves up and down with respect to the base 73, and the inner wall 79 of the cleaning chamber is moved. The size of the gap 80 between the lower end of the stage and the stage body 75 can be controlled. That is, by finely adjusting the differential pressure between the cleaning chamber 51 and the separation chamber 52, the pressure inside the cleaning chamber 51 and the pressure inside the separation chamber 52 can be adjusted more finely.

In the semiconductor wafer cleaning apparatus shown in FIGS. 2 and 3, the cleaning chamber 51 having the structure shown in FIG. 1 is centered and the separation chamber 52 is integrally formed around the cleaning chamber 51 to form a double structure. The high-pressure container 34 having is formed. However, the present invention is not limited to this, and the gap 26 between the upper lid 22 and the stage 21 of the cleaning tank having the structure shown in FIG. 1 and the separation tank formed separately from this cleaning tank are provided. It does not matter if the supercritical fluid is discharged from the discharge port provided in the upper part of the separation tank by connecting the injection port provided in the lower part. Further, in the semiconductor wafer cleaning apparatus shown in FIG. 4 in which the size of the gap between the stage and the inner wall of the cleaning chamber can be controlled, the size of the gap 80 is controlled by moving the stage main body 75 on the stage 72 side. . However, there is no problem even if the inner wall 79 side of the cleaning chamber can be moved up and down.

[0039]

As is apparent from the above, in the semiconductor wafer cleaning apparatus according to the first aspect of the present invention, the stage on which the wafer carrier carrying the wafer to be cleaned is placed is covered by the upper lid, and the cleaning substance supply means is provided. While supplying the supercritical cleaning substance from the injection port on the upper lid, the cleaning substance is discharged from the gap formed between the upper lid and the stage by the cleaning substance discharging means, and the cleaning amount is discharged by the discharging amount adjusting means. Since the pressure of the cleaning substance in the upper lid is maintained at a constant pressure equal to or higher than the critical pressure by adjusting the discharge amount of the substance, the inside of the upper lid is brought into a supercritical state without sealing the space between the upper lid and the stage with a sealing material. Can be kept. Therefore, a sealing material for sealing the space between the upper lid and the stage is unnecessary, and deterioration of the sealing material and contamination of the wafer to be cleaned by the sealing material are eliminated.

Further, the cleaning substance in a supercritical state supplied from the upper part of the cleaning chamber formed by covering the stage with an upper lid regularly flows toward the gap in the lower part of the cleaning chamber,
It is quickly discharged from this gap. Therefore, the contaminants extracted from the wafer to be cleaned into the cleaning substance are quickly discharged from the gap and do not contaminate the wafer to be cleaned or the inner surface of the upper lid.

That is, the semiconductor wafer cleaning apparatus of the present invention can be easily automated without lowering the operating rate due to the replacement of the sealing material or the cleaning of the high-pressure container.

Further, in the semiconductor wafer cleaning apparatus according to the second aspect of the present invention, the stage has an outer peripheral portion extending to the periphery, the upper lid has a chamber adjacent to the periphery, and the upper lid has a chamber. By forming a cleaning chamber and a separation chamber, which are communicated with each other in the gap by covering the stage with a sealing means, and supplying a cleaning substance in a supercritical state from an injection port in the upper part of the cleaning chamber, the separation chamber Drain the cleaning substance from the upper outlet,
By adjusting this emission amount with the emission amount adjusting means,
While maintaining the cleaning substance pressure in the cleaning chamber at a constant pressure above the critical pressure, while maintaining the cleaning substance pressure in the separation chamber at a constant pressure lower than the critical pressure, seal between the cleaning chamber and the separation chamber by a sealing material. Without doing so, the cleaning chamber is kept in a supercritical state, and the cleaning substance in the supercritical state supplied from the inlet of the upper part to the cleaning chamber flows in an orderly manner toward the gap of the lower part and is quickly discharged. Therefore, there is no deterioration of the sealant or contamination of the wafer to be cleaned by the sealant, and contamination of the wafer to be cleaned or the inner surface of the upper lid by the contaminant extracted as the cleaning substance is prevented.

Further, the supercritical cleaning substance discharged from the gap of the cleaning chamber flows into the separation chamber integrally formed in the cleaning chamber and has a constant pressure lower than the critical pressure. Therefore, the contaminants dissolved in the cleaning substance are promptly separated. Thus, the cleaning of the wafer to be cleaned with the cleaning substance in the supercritical state and the separation of the contaminant from the cleaning substance can be continuously performed in one high pressure container.

The invention according to claim 3 is formed when the stage is covered by the upper cover because at least one of the lower end of the wall of the upper cover and the upper surface of the stage is movable. It is possible to adjust the interval of the above-mentioned gap. Therefore, the cleaning substance pressure inside the wall of the upper lid or the cleaning substance pressure in the chamber outside the wall can be adjusted to be more optimal.

[Brief description of drawings]

FIG. 1 is a diagram showing a basic structure relating to a cleaning tank in a semiconductor wafer cleaning apparatus of the present invention.

FIG. 2 is a fluid circuit diagram in the semiconductor wafer cleaning apparatus of the present invention.

FIG. 3 is a diagram showing the structure of the high-pressure container in FIG.

FIG. 4 is a diagram showing a structure of a stage different from that of FIG.

FIG. 5 is a phase diagram for explaining a supercritical state.

FIG. 6 is a diagram showing a conventional cleaning device using a supercritical liquid.

[Explanation of symbols]

22 ... Top lid, 23 ... Inlet, 3
1 ... cylinder, 32 ... pressure regulating valve,
33 ... Exhaust valve, 34 ... High-pressure container,
36 ... Pressure pump, 37 ... Heater, 3
8 ... Cooler, 41 ... Circulation pump,
51 ... Washing room, 52 ... Separation room, 5
4 ... injection pipe, 55 ... discharge pipe, 2
1,56,72 ... stage, 57,79 ... inner wall,
58 ... Outer wall, 59, 71 ... Elevating table, 25, 60, 76 ... Wafer carrier, 61, 75 ...
Stage body, 26, 63, 80 ... Gap, 6
4 ... Sealing material, 24, 65 ... Wafer to be cleaned, 6
6 ... metal fittings.

Claims (3)

[Claims] 1. A stage on which a wafer carrier on which a wafer to be cleaned is mounted is placed, and a box is turned down, and a cleaning substance injection port is provided on an upper part thereof to form a gap at a lower end of a wall. An upper lid that covers the stage, a cleaning material supply unit that supplies the cleaning material that has been pressurized and heated to a supercritical state from the inlet of the upper lid, and the upper lid when the stage is covered with the upper lid. The cleaning substance discharge means for discharging the cleaning substance from the gap formed between the stage and the stage, and the amount of the cleaning substance discharged by the cleaning substance discharge means are adjusted so that the pressure of the cleaning substance in the wall is not less than the critical pressure. 2. A semiconductor wafer cleaning apparatus, comprising: a discharge amount adjusting means for maintaining a constant pressure. 2. The semiconductor wafer cleaning apparatus according to claim 1, wherein the stage has an outer peripheral portion extending to the periphery, and the upper lid is formed adjacent to the periphery and has a cleaning material on the upper portion. With a chamber provided with a discharge port, when the stage is covered with an upper lid, a sealing means for sealing between the outer wall of the upper lid and the outer peripheral portion of the stage is provided, and the cleaning substance discharging means is By discharging the cleaning substance in the chamber from the discharge port of the upper lid, the cleaning substance in the wall is discharged from the gap, and the discharge amount adjusting means is discharged by the cleaning substance discharging means. The amount of the cleaning substance is adjusted so that the pressure of the cleaning substance inside the wall is kept at a constant pressure above the critical pressure, while the pressure of the cleaning substance in the chamber outside the wall is kept at a constant pressure lower than the critical pressure. Na Cleaning apparatus for semiconductor wafers, characterized in that is. 3. The semiconductor wafer cleaning apparatus according to claim 1, wherein at least one of a lower end of a wall of the upper lid and an upper surface of the stage is movable in a direction of opening and closing the gap. An apparatus for cleaning a semiconductor wafer, wherein an interval of the gap formed when the stage is covered by the upper cover is adjustable.