JP3135209B2 - Semiconductor wafer cleaning equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art A supercritical liquid is a state having an intermediate property between a liquid and a gas obtained at a critical pressure Pc or more and a critical temperature Tc or more as shown in a 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 a gas is suitable for cleaning fine parts. Further, when the pressure is reduced to the critical pressure or less, since the gas becomes gas, there is an advantage in that the drying step only requires a reduced pressure.

As the supercritical liquid, CO ₂ is often used. 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, it can be used industrially safely. 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, there is a cleaning apparatus as shown in FIG. 6 for cleaning using the above-mentioned supercritical liquid. This cleaning apparatus includes a CO ₂ cylinder 1 serving as a gas supply source, a pressure regulating valve A, a pressure regulating 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. It is schematically constructed by connecting a valve 8, a replenishing valve 9 and an exhaust valve 10 with a pressure-resistant tube. Note that the lid 13 of the cleaning tank 2 is sealed with a sealing material 14.

Hereinafter, the operation of the cleaning apparatus having the above configuration will be briefly described. First, the wafer 1 to be cleaned is
1 is put in the washing tank 2 and sealed with the lid 13. Subsequently, 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, then is raised to a pressure higher than the critical pressure by the pressure pump 5, and is further raised to a temperature higher than the critical temperature by the heater 6. The temperature is raised to a supercritical state and supplied to the cleaning tank 2. At this 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 inside of the separation layer 3 is maintained at a pressure lower than the critical pressure by the pressure regulating valve B.

[0007] By the above operation, the flow of the fluid becomes as shown by the arrow, and the contaminants on the object 11 to be cleaned are dissolved in the supercritical liquid in the cleaning tank 2. Further, the supercritical liquid in which the contaminants are dissolved becomes lower than the critical pressure in the separation tank 3 and turns into a gas, which is separated from the contaminants. The contaminants thus separated are deposited on the bottom of the separation tank 3, and the 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.

[0008] As another cleaning apparatus using a supercritical liquid, a cleaning apparatus having a horizontal cleaning tank and a lid and an opening / closing portion for the lid (Japanese Patent Laid-Open No. 4-17333), a supercritical state, and the like. A washing apparatus in which the extraction chamber is surrounded by a separation chamber to integrally form the extraction chamber and the separation chamber, and the supercritical fluid flows into and out of the extraction chamber from the same direction via a lid (Japanese Patent Laid-Open No. Hei 4- 39499).

[0009]

However, the conventional cleaning apparatus using a supercritical liquid has the following problems. (1) The cleaning tank 2 and the extraction chamber for storing the object to be cleaned are high-pressure vessels, and the sealing material 14 is required to improve the airtightness of the lid. When the sealing member 14 is formed of a resin, the sealing member 14 is easily deteriorated by being exposed to a supercritical liquid having a high ability to extract fat components, and the operation time of the apparatus is increased due to an increase in the frequency of replacement of the sealing member 14. descend. Further, contamination of the object to be cleaned and the side wall of the high-pressure container is caused by the extracted oil and fat component of the sealing material 14. On the other hand, since the metal sealing material cannot be used repeatedly, it needs to be replaced frequently, resulting in a significant increase in running cost.

(2) In the washing apparatus shown in FIG. 6 or the high-pressure vessel in the washing apparatus in which the extraction chamber and the separation chamber are integrally formed, the inlet and the outlet for the supercritical liquid are provided on the same surface. The structure is such that turbulence easily occurs. For this reason, re-adhesion of contaminants and generation of particles to the object to be cleaned and the side wall of the high-pressure container are likely to occur, and the cleaning effect is reduced.

(3) In a cleaning apparatus having a horizontal cleaning tank and a lid and an opening / closing section, the opening / closing section comes into contact with a supercritical liquid, so that contamination or deterioration occurs.

[0012] All of these problems cause a reduction in operating time due to replacement of the sealing material and cleaning of the side wall of the high-pressure vessel.
This hinders the automation of the cleaning device.

SUMMARY OF THE INVENTION An object of the present invention is to provide a high-throughput semiconductor wafer cleaning apparatus which can easily be automated by preventing deterioration of a sealing material and preventing contamination of an object to be cleaned and a side wall of a high-pressure container. Is to provide.

[0014]

In order to achieve the above object, the invention according to claim 1 comprises a stage on which a wafer carrier on which a wafer to be cleaned is mounted is mounted, and a box having a prone shape, An upper lid that covers the stage by forming a gap at the lower end of the wall, and a cleaning substance that has been heated to a supercritical state by pressurization and heating is supplied from the inlet of the upper lid. Cleaning substance supply means, and a cleaning substance discharge means for discharging the cleaning substance from a gap formed between the upper lid and the stage when the stage is covered with the upper lid,
Discharge amount adjusting means for adjusting the amount of the cleaning substance discharged by the cleaning substance discharging means to maintain the pressure of the cleaning substance in the wall at a constant pressure equal to or higher than a critical pressure is provided.

In the above configuration, when the stage on which the wafer carrier on which the wafer to be cleaned is mounted is placed on 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, the cleaning substance in a supercritical state is supplied from the inlet of the upper lid by the cleaning substance supply means, and the cleaning substance is discharged from the gap by the cleaning substance discharge means. At this time, the discharge amount of the cleaning substance is adjusted 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 by the discharge amount adjusting means. In this manner, the wafer to be cleaned is cleaned by the supercritical cleaning material that flows from the upper inlet of the upper lid toward the lower gap and is discharged quickly from the gap.

According to a second aspect of the present invention, in the apparatus for cleaning a semiconductor wafer according to the first aspect of the present invention, the stage has an outer peripheral portion extending around the periphery, and the upper lid is adjacent to the periphery. Having a chamber formed and provided with a discharge port of a cleaning substance at an upper portion, when the stage is covered with an upper lid, a sealing means for sealing between an outer wall of the upper lid and an outer peripheral portion of the stage is provided. , The cleaning substance discharging means includes:
The cleaning substance in the wall is discharged from the gap by discharging the cleaning substance in the room from the discharge port in the upper lid, 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 in 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 having.

In the above configuration, when the stage on which the wafer carrier mounting the wafer to be cleaned is mounted is covered by the upper lid, the space between the outer wall of the upper lid and the outer peripheral portion of the stage is sealed by the sealing means. On the other hand, a gap is formed between the lower end of the upper lid wall and the upper surface of the stage. Thus, a washing chamber inside the wall and a separation chamber outside the wall in the upper lid are formed. Then, the cleaning substance in a supercritical state is injected into the cleaning chamber from the inlet of the upper lid by the cleaning substance supply means, and the cleaning substance in the separation chamber is discharged from the discharge port in the upper lid by the cleaning substance discharge means. At this time, the discharge amount of the cleaning substance is adjusted by the discharge amount adjusting means so that the cleaning substance pressure in the cleaning chamber is maintained at a constant pressure equal to or higher than the critical pressure, while the cleaning substance pressure in the separation chamber is controlled to the critical pressure. It is kept at a lower constant pressure. In this way, the wafer to be cleaned is cleaned by the supercritical cleaning substance which flows from the upper inlet in the cleaning chamber toward the lower gap and is quickly discharged from the gap. Further, the cleaning substance discharged into the separation chamber from the gap becomes a gaseous state, and contaminants are quickly separated.

According to a third aspect of the present invention, in the apparatus for cleaning a semiconductor wafer according to the first aspect of the present invention, at least one of the lower end of the wall of the upper lid and the upper surface of the stage opens and closes the gap. , And the gap between the gaps formed when the stage is covered with the upper lid can be adjusted.

In the above configuration, when the stage is covered with the upper lid, at least one of the lower end of the wall of the upper lid or the upper surface of the stage, which forms a gap, is moved, and the interval of the gap is optimally adjusted. Is done. Thus, the cleaning substance pressure inside the wall on the top lid and the cleaning substance pressure in the chamber outside the wall are adjusted to be more optimal.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments. FIG. 1 is a diagram showing a basic configuration of a cleaning tank in a semiconductor wafer cleaning apparatus according to the present embodiment. The main cleaning tank is roughly composed of a stage 21 on which a wafer carrier 25 on which a plurality of wafers 24 to be cleaned are mounted is mounted, and an upper lid 22 having a box-like shape and covering the stage 21. The upper lid 22 is provided at the upper center thereof with an inlet 23 into which a supercritical cleaning substance (supercritical fluid) is injected, and forms a gap 26 to cover the stage 21. Then, while the supercritical fluid pressurized and heated to the supercritical state is injected from the injection port 23, the stage 21 and the upper lid 2 are injected.
The supercritical fluid is exhausted from the gap 26 with the second. At this time, by balancing the amount of supercritical fluid discharged out of the cleaning tank from the gap 26 and the amount of supercritical fluid injected from the injection port 23, the inside of the cleaning tank can be sealed without sealing the cleaning tank with a sealing material. Can be kept in a supercritical state. In this way, a steady state 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 24 to be cleaned in the supercritical state is formed.

As a result, in the present embodiment, a sealing material is not required in the cleaning tank, and deterioration of the sealing material and contamination of the wafer 24 to be cleaned by the sealing material can be eliminated. The contaminants extracted into the supercritical fluid from the surface of the wafer 24 to be cleaned are quickly discharged out of the cleaning tank by the flow 27 of the supercritical fluid. Therefore, the wafer to be cleaned 2
4 and the inner wall of the upper lid 22 are prevented from adhering contaminants in the supercritical fluid.

When a separation tank is provided adjacent to the side where the supercritical fluid is exhausted from the gap 26, the cleaning is performed by forcibly sucking the supercritical fluid from the separation tank using a circulation pump or the like. The pressure difference between the tank and the separation tank is increased.

Hereinafter, a specific example of an apparatus for cleaning a semiconductor wafer using a cleaning tank having the above-described basic structure will be described. FIG. 2 is a fluid circuit diagram of the semiconductor wafer cleaning apparatus according to the present embodiment. The present semiconductor wafer cleaning apparatus includes a cylinder 31 for supplying CO ₂ as a supercritical fluid,
Pressure regulating valve 32, exhaust valve 33, high pressure vessel 34 having a double structure integrating a washing tank and a separation tank, a filter 35, a pressure pump 36, a heater 37, a cooler 38, a cylinder valve 39.
And a replenishing valve 40 connected by a pressure-resistant tube.

As shown in FIG. 3, the high-pressure vessel 34
Cleaning chamber 51 having the same basic structure as the cleaning tank shown in FIG.
And a separation chamber 52 integrally provided around the washing chamber 51.
And a double structure consisting of In addition, the high pressure vessel 34
When viewed from a structural point of view, it 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 such that a shallow pot is turned down. An injection pipe 54 extending outward is provided at the upper center of the upper lid 53, and a discharge pipe is provided around the injection pipe 54. 55 are provided. In addition, the injection pipe 54 and the discharge pipe 5
An annular inner wall 57 extending inward is formed between the cleaning chamber 5 and the central cleaning chamber 5.
1 and the surrounding separation chamber 52. Further, the separation chamber 52 is separated from the external environment by an outer wall 58 forming an outer shell of the upper lid 53.

The stage 56 includes a stage main body 61 mounted on an elevating table 59 and on which a wafer carrier 60 is mounted.
And an outer peripheral portion 62 extending from the stage main body 61 to the outer periphery to form the bottom of the separation chamber 52. Then, the stage 56 is moved up to a predetermined position by the elevating table 59 and the upper lid 53 is moved.
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 main body 61, 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. When the upper lid 53 is closed in this way, a double-structure high-pressure vessel 34 having a separation chamber 52 around the cleaning chamber 51 having the same structure as the cleaning tank shown in FIG. 1 is formed.

Here, the injection pipe 5 into which the supercritical fluid is injected
4 is provided at the upper part of the cleaning chamber 51, while a discharge pipe 55 for discharging the supercritical fluid in which the pollutant is dissolved
And the diameter thereof is set to be larger than the diameter of the injection tube 54. Then, in order to lower 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 It flows neatly parallel to the surface of the wafer 65.

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

The semiconductor wafer cleaning apparatus having the above configuration cleans a 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 65 to be cleaned is set on the stage main 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 to the state shown in FIG.

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

When the supercritical fluid CO ₂ into which the organic contaminants are dissolved reaches the separation chamber 52 from the gap 63 at the lower end of the inner wall 57 of the cleaning chamber 51 and reaches a pressure lower than the supercritical pressure, The contaminants are separated from the gaseous CO ₂ and accumulated in the grooves formed on the outer peripheral portion 62 of the stage 56. When cleaning is completed, 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 atmospheric pressure.

Here, the cleaning chamber 51 has a height / diameter such that the supercritical fluid CO ₂ injected from the injection pipe 54 flows parallel to the surface of the wafer 65 to be cleaned (that is, from above to below). Are set so that the ratio becomes “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 apparatus for cleaning a semiconductor wafer according to the present embodiment is a high-pressure semiconductor which is roughly constituted by the stage 56 on which the wafer carrier 60 is mounted, and the upper lid 53 having the gap 63 and covering the stage 56. Having a container 34,
When the stage 56 is sealed with the upper lid 53, a cleaning chamber 51 having the same basic structure as the cleaning tank shown in FIG. 1 and a separation chamber 52 provided integrally around the cleaning chamber 51 are formed. In addition, an injection pipe 54 is provided at the upper center of the washing chamber 51, and a discharge pipe 55 is provided at the upper part of the separation chamber.

Then, the diameter of the discharge pipe 55 is changed to the injection pipe 5.
4 and the circulation pump 41 is forcibly sucked into the separation chamber 52. As a result, by adjusting the opening of the pressure regulating 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. The inside is kept at a constant pressure lower than the critical pressure.

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

FIG. 4 shows a state in which the size of the gap between the stage on which the wafer carrier is mounted and the inner wall of the cleaning chamber is controlled.
FIG. 5 is a cross-sectional view of a stage in a semiconductor wafer cleaning apparatus capable of finely adjusting a pressure difference between a cleaning chamber 51 and a separation chamber 52. The stage 72 has a circular base 73 placed on the lift 71.
An outer peripheral portion 74 provided on the outer periphery of the base 73 to form the bottom of the separation chamber; and a stage body 7 mounted on the base 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, so that contaminants separated from the supercritical fluid in the separation chamber are accumulated. The stage body 75 has a shape with a bottomed cylinder turned down, and a wafer carrier 76 is placed on the upper surface. On the inner wall of the cylindrical portion, a male screw formed at the step of the base 73 is provided. A female screw 78 is formed to be screwed to 77.

Accordingly, by rotating the stage main body 75 screwed to the base 73 by a rotation drive 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 rotated. 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 pressure difference between the cleaning chamber 51 and the separation chamber 52, the pressure in the cleaning chamber 51 and the pressure in the separation chamber 52 can be more finely adjusted.

In the apparatus for cleaning a semiconductor wafer shown in FIGS. 2 and 3, a cleaning chamber 51 having the structure shown in FIG. 1 is centered, and a separation chamber 52 is formed integrally therewith to form a double structure. To form a high-pressure container 34. However, the present invention is not limited to this, and a gap 26 between the upper lid 22 and the stage 21 of the cleaning tank having the structure shown in FIG. The supercritical fluid may be discharged from the outlet provided at the upper part of the separation tank by connecting the inlet provided at the lower part. In the semiconductor wafer cleaning apparatus shown in FIG. 4 which can control the size of the gap between the stage and the inner wall of the cleaning chamber, the size of the gap 80 is controlled by moving the stage body 75 on the stage 72 side. . However, the inner wall 79 of the cleaning chamber may be vertically movable.

[0039]

As is apparent from the above description, in the semiconductor wafer cleaning apparatus according to the first aspect of the present invention, the stage on which the wafer carrier on which the wafer to be cleaned is mounted is covered with the upper lid, and the cleaning material supply means is provided. While the supercritical cleaning substance is supplied from the inlet at the top of 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 is performed by the discharge 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 the deterioration of the sealing material and the contamination of the wafer to be cleaned by the sealing material are eliminated.

Further, the supercritical cleaning substance supplied from the upper part of the cleaning chamber, which is formed by covering the stage with an upper lid, flows steadily toward the gap at 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 and the inner surface of the upper lid.

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

According to a second aspect of the present invention, in the semiconductor wafer cleaning apparatus, the stage has an outer peripheral portion extending around the periphery, and the upper lid has a chamber adjacent to the periphery. The stage is covered and sealed by a sealing means to form a washing chamber and a separation chamber that are communicated with each other through the gap, and a supercritical cleaning substance is supplied from an inlet above the washing chamber, while the separation chamber is supplied. Drain the cleaning substance from the upper outlet,
By adjusting this emission by the emission adjustment means,
Since the pressure of the cleaning substance in the cleaning chamber is maintained at a constant pressure equal to or higher than the critical pressure, while the pressure of the cleaning substance in the separation chamber is maintained at a constant pressure lower than the critical pressure, the space between the cleaning chamber and the separation chamber is sealed with a sealing material. The cleaning chamber is kept in a supercritical state without performing the cleaning process, and the supercritical cleaning material supplied from the upper inlet to the cleaning chamber flows toward the lower gap and is discharged immediately. Therefore, there is no deterioration of the sealing material or contamination of the cleaning target wafer by the sealing material, and contamination of the cleaning target wafer and 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 in the cleaning chamber flows into a separation chamber formed integrally with the cleaning chamber and has a constant pressure lower than the critical pressure. Therefore, contaminants dissolved in the cleaning substance are quickly separated. Thus, the cleaning of the wafer to be cleaned with the supercritical cleaning substance and the separation of the contaminants from the cleaning substance can be performed continuously in one high-pressure vessel.

Further, the invention according to claim 3 is formed when the stage is covered with 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. The gap can be adjusted. Therefore, the pressure of the cleaning substance inside the wall in the upper lid or the pressure of the cleaning substance in the chamber outside the wall can be adjusted to be more optimal.

[Brief description of the drawings]

FIG. 1 is a diagram showing a basic structure of 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 view showing a structure of a high-pressure container in FIG. 2;

FIG. 4 is a diagram showing a structure of a stage different from that of FIG. 3;

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

FIG. 6 is a view showing a conventional cleaning apparatus using a supercritical liquid.

[Explanation of symbols]

22 ... top lid, 23 ... injection port, 3
1 ... cylinder, 32 ... pressure regulating valve,
33 ... exhaust valve, 34 ... high pressure vessel,
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 ... elevator, 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.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/304 B08B 3/02

Claims (3)

(57) [Claims] 1. A stage on which a wafer carrier on which a wafer to be cleaned is mounted is mounted, and a box is formed in a protruding shape, and an inlet for a cleaning substance is provided at an upper portion, and a gap is formed at a lower end of a wall. An upper lid that covers the stage, and a cleaning substance supply unit that supplies a cleaning substance that has been heated and pressurized to a supercritical state from an inlet of the upper lid, and the upper lid when the stage is covered with the upper lid. A cleaning substance discharging means for discharging the cleaning substance from a gap formed between the stage and the cleaning substance; adjusting the amount of the cleaning substance discharged by the cleaning substance discharging means so that the pressure of the cleaning substance in the wall is equal to or higher than the critical pressure; A semiconductor wafer cleaning apparatus, comprising: a discharge adjusting means for maintaining the discharge pressure at a constant pressure. 2. The apparatus for cleaning a semiconductor wafer according to claim 1, wherein the stage has an outer peripheral portion extending around the periphery, and the upper lid is formed adjacent to the periphery and has an upper portion formed of a cleaning substance. Along with a chamber provided with a discharge port, when the stage is covered with an upper lid, a sealing means for sealing between an outer wall of the upper lid and an outer peripheral portion of the stage is provided. By discharging the cleaning substance in the chamber from the discharge port in 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 to maintain the pressure of the cleaning substance in the wall at a constant pressure equal to or higher than the critical pressure, while maintaining the pressure of the cleaning substance in the chamber outside the wall at a constant pressure lower than the critical pressure. What Cleaning apparatus for semiconductor wafers, characterized in that is. 3. The apparatus for cleaning a semiconductor wafer according to claim 1, wherein at least one of a lower end of a wall of the upper lid or an upper surface of the stage is movable in a direction for opening and closing the gap. An apparatus for cleaning a semiconductor wafer, wherein an interval of the gap formed when the stage is covered with an upper lid is adjustable.