JP2000243739A - Wafer chemical polishing method and apparatus - Google Patents

Abstract

(57) [PROBLEMS] To improve the quality and reduce the cost by performing means for preventing the processing liquid from adhering to the non-processed surface in the chemical polishing of a semiconductor wafer . Kind Code: A1 A vacuum chuck (10) having a circular suction surface (10c) having a diameter slightly smaller than the diameter of a wafer (W) is chucked in a state in which the processing surface of the wafer (W) faces upward and the peripheral edge is overhanged. A purge gas is blown obliquely upward from the outer peripheral portion of the upper end of the vacuum chuck (10) to the lower surface of the overhanging outer peripheral portion, so that the chemical polishing treatment liquid and the cleaning liquid are scattered from the outer periphery of the wafer, and the non-processed surface is removed. It prevents adhesion and wraparound of mist.
The conventional taping for protecting the non-processed surface of the wafer can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for chemically polishing a semiconductor wafer.

[0002]

2. Description of the Related Art Conventionally, chemical polishing of a semiconductor wafer surface has been performed by holding a wafer on a mechanical chuck or a vacuum chuck and spraying a processing liquid and a cleaning liquid onto the surface.

[0003]

In the conventional chemical polishing of the surface of a wafer, a chemical polishing treatment liquid such as nitric acid or hydrofluoric acid adheres to the back surface of the wafer, or the mist of the treatment liquid wraps around the back surface. However, there is a problem that the quality is deteriorated and the yield of the product is reduced. As a countermeasure, it has conventionally been necessary to perform taping on the back side of the wafer, and this taping requires a large amount of labor, leading to an increase in cost. I was

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a vacuum chuck having a vacuum suction surface at an upper end, the back surface of the wafer being suctioned, and the front surface facing upward.
A chemical polishing solution or cleaning solution is sprayed from the upper nozzle onto the front surface, and a purge gas is blown from the upper peripheral portion of the vacuum chuck to the peripheral portion of the back surface of the wafer, so that the chemical polishing solution or cleaning solution is applied to the outside of the circumference. To prevent adhesion to the back surface and wraparound of the processing liquid mist to the back surface.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a vacuum chuck having a circular suction surface at the upper end and a wafer having a diameter larger than the circular suction surface and a rear surface being suctioned with its peripheral portion protruding from the outer periphery of the vacuum chuck. After the chemical polishing is performed by spraying a chemical polishing liquid such as nitric acid or hydrofluoric acid on the upper surface while rotating, when cleaning is performed by spraying a cleaning liquid such as pure water, the back surface of the wafer is removed from the outer periphery of the upper end of the rotary vacuum chuck. This is a chemical polishing treatment method for a wafer in which a gas for purging such as nitrogen gas is blown to a circumferential portion to scatter a chemical polishing treatment liquid and a cleaning liquid outward of the circumference.

Further, an apparatus for carrying out the above-mentioned chemical polishing treatment method for a wafer is provided with a spline formed on the outer periphery, a tubular rotating elevating shaft having an axial hole, and a ball spline bearing having a pulley for transmitting rotation. Thus, the frame is supported upright so as to be able to rotate and ascend and descend on the frame, and a vacuum chuck for adsorbing and holding a wafer to be chemically polished is attached to the upper end of this rotating and elevating shaft.

In this vacuum chuck, a circular suction surface having a smaller diameter than the wafer is formed on the upper surface by opening a plurality of suction grooves, and the suction grooves communicate with a suction center hole penetrating the center of the circle. The purge gas supplied through the shaft through hole of the rotary elevating shaft is connected to a suction pipe connected to an external vacuum pump through the shaft through hole of the rotary elevating shaft. An annular outlet gap that opens obliquely upward at the outer periphery of the upper end of the vacuum chuck, an annular space that communicates with the lower end of the annular outlet gap, and that communicates with the annular space and the axial through hole. A purge gas passage is provided.

Further, a filter unit for dust removal communicating with a purge gas communication passage provided in a lower end member of the elevating shaft provided at a lower end of the rotary elevating shaft is used as a lower end bearing for rotatably supporting the lower end member of the elevating shaft. May be attached.

[0009]

Embodiments will be described with reference to the drawings.
Reference numeral 1 denotes a rotary elevating shaft, which has a spline 1a formed of a plurality of vertical grooves on the outer circumference, a shaft through hole 1b, and a tubular spline shaft having a flange 1c formed at an upper end thereof. The two ball spline bearings 2, 2 attached to the frame 13 and arranged in series in the vertical direction are supported so as to be rotatable and vertically movable.

The ball spline bearings 2, 2 are rotatably supported by an outer cylinder 2a mounted on a frame 13 by an outer bearing 2b, and an elevating guide bearing 2d is provided on the inner periphery of the upper and lower ends of the inner cylinder 2c. The balls of the elevating guide bearing 2d are fitted into the plurality of vertical grooves of the spline 1a provided on the outer periphery of the elevating shaft 1, and serve as the elevating guide of the rotatable elevating shaft 1. Is vertically movable with respect to the inner cylinder 2c of the upper and lower two ball spline bearings 2, and is rotatably supported by the outer bearing 2b integrally with the inner cylinder 2c with respect to the outer cylinder 2a.

A pulley 3 is attached to the lower end of the inner cylinder 2c of the lower ball spline bearing 2 of the two ball spline bearings 2 and 2 and driven by an electric motor (not shown) via a belt 3a. The ball of the elevating guide bearing 2d fits into the spline 1a together with the inner cylinder 2c, and the rotary elevating shaft 1 rotates.

Numeral 4 denotes an elevating airtight cylinder, which has a structure in which the upper end of the cylinder is closed, covers the upper end of the rotary elevating shaft 1 and is mounted on a flange 1c at the upper end of the rotary elevating shaft 1. The fixed airtight cylinder 4 attached to the frame 13
a is provided with a confidential seal 4b on the inner periphery of the upper end, and when the elevating and lowering airtight cylinder 4 moves up and down while rotating together with the rotary elevating shaft 1, the airtightness with the outer peripheral portion of the ascending and descending airtight cylinder 4 is maintained. The liquid and the cleaning liquid are prevented from scattering and adhering to the rotating shaft 1 and the ball spline bearing 2.

A lower end member 5 of the elevating shaft is attached to the lower end of the rotary elevating shaft 1. The lower end member 5 of the elevating shaft is connected to a lower end bearing 7 attached to an elevating plate 6 which moves up and down by another elevating means (not shown). The lower shaft member 5 is rotatably supported by two bearings 7a, 7a. The lower shaft member 5 has a shaft through hole 1b of the rotating shaft 1 and a vacuum passage 5a communicating with the outside of the lower shaft bearing 7. A purge gas communication passage 5b communicating with the axial through hole 1b and the outside of the lower end is provided.

A suction pipe 8 is inserted into the through hole 1b of the shaft 1 of the rotary elevating shaft 1. The lower end of the suction pipe 8 communicates with the vacuum passage 5a. The vacuum passage 5a is connected to a vacuum pump passage 9 connected to the lower end bearing 7.
Through an external vacuum pump (not shown). The vacuum pump path 9 includes an electromagnetic valve 9a,
An air suction passage 9b for preventing excessive suction is provided with an air filter 9c and a solenoid valve 9d that opens when necessary.

Reference numeral 10 denotes a vacuum chuck, which comprises a lower body 10a and an upper body 10b. The lower body 10a has a concave upper surface except for the peripheral portion of the thick disk, and the upper end of the peripheral portion descends toward the center. An upper body 10b having a substantially cup-shaped outer shape and having a circular suction surface 10c whose diameter is slightly smaller than that of the disk-shaped object W fits into the central concave portion and is joined to the central concave portion. The lower end of the lower body 10a
It is attached to the upper end of an elevating airtight cylinder 4 which covers the upper end of the rotary shaft, and is integrated with the rotary elevating shaft 1.

The upper end of a suction pipe 8 passing through the axial through hole 1b of the elevating rotary shaft 1 is opened in a suction center hole 10d penetrating through the center of the vacuum chuck 10.
A plurality of concentric grooves formed on the circular suction surface 10c and suction grooves 10e formed of radial grooves communicate with each other.

An annular space 10f is provided between the lower body 10a and the upper body 10b at a position close to the outer periphery, and the annular space 10f
An annular gap 10g is formed obliquely upward toward the upper end of the outer periphery so as to communicate with the annular space 10f and the rotary elevating shaft 1
Gas upper passage 10 communicating with the axial through hole 1b
h forms the up-and-down airtight cylinder 4, the lower body 10a, and the upper body 10b in communication.

Reference numeral 11 denotes a filter unit, and the lower end bearing 7
A filter 11a is sandwiched by a filter holding plate 11b, and a purge gas supply path 12 connected to a nitrogen gas container (not shown) is provided at the lower end of the filter unit 11 with an electromagnetic valve 12a. After the purge gas is filtered through the filter 11a, the purge gas communication hole 5b provided in the lower end member 5 of the elevating shaft is connected.
After passing through the through hole 1b of the rotary elevating shaft 1 and passing through the purge gas passage 10h provided in the vacuum chuck 10 to the annular space 10f, it is sucked from the annular blowing gap 10g to the circular suction surface 10c and rotated. Semiconductor wafer W
The chemical polishing treatment liquid and the cleaning liquid are scattered from the circumference by spraying obliquely from below onto the circumference of the back surface of the substrate.

Numeral 14 denotes an injection nozzle which moves up and down in synchronism with the elevating of the rotary elevating shaft 1 while always keeping a constant interval with the vacuum chuck 10. FIG.
4 shows a state in which chemical polishing treatment liquid such as nitric acid, hydrofluoric acid or the like is sprayed in a state where it is most lowered with respect to the frame 13 to perform chemical polishing. FIG. Thus, a state in which the cleaning is performed by injecting pure water from the injection nozzle 14 is shown. The above-described injection of the purge gas is operated both during the chemical polishing and during the cleaning.

[0020]

The present invention is embodied in the form described above and has the following effects.

By using a vacuum chuck, the entire outer periphery of the wafer can be held in an open state, and a purge gas is blown from the back side of the opened circumferential portion at the time of chemical polishing processing and cleaning, thereby performing chemical polishing. By scattering the processing liquid and the cleaning liquid, it is possible to prevent the chemical polishing processing liquid and the cleaning liquid from adhering to the back surface of the disk-shaped object and to prevent mist from flowing around, thereby obtaining a clean product.

In order to prevent the chemical polishing treatment liquid and the cleaning liquid from adhering to the back surface, taping on the back surface, which is conventionally performed, becomes unnecessary, and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a view showing a state in which a main part of the apparatus of the present invention is subjected to a chemical polishing process with a vacuum chuck being at a lower position.

FIG. 2 is a diagram showing a state in which a main part of the apparatus of the present invention is subjected to a cleaning process in which a vacuum chuck is positioned at a higher position.

FIG. 3 is an enlarged sectional view of a vacuum chuck.

FIG. 4 is a plan view of the same.

[Explanation of symbols]

 W Wafer 1 Rotating elevating shaft 1a Spline 1b Shaft center through hole 1c Flange 2 Ball spline bearing 3 Pulley 4 Elevating airtight cylinder 4a Fixed airtight cylinder 4b Hermetic seal 5 Elevating shaft lower end member 5a Vacuum passage 5b Purging gas communication passage 6 Elevating plate 7 Lower end bearing 8 Suction pipe 9 Vacuum pump path 10 Vacuum chuck 10a Lower body 10b Upper body 10c Circular suction surface 10d Suction center hole 10e Suction groove 10f Annular space 10g Annular gap 10h Purging gas passage 11 Filter unit 11a Filterer 11b Filter holding plate 12 Gas supply path for purging 13 Frame 14 Injection nozzle

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[Procedure amendment]

[Submission date] February 22, 1999 (1999.2.2
2)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction contents]

[Document Name] Statement

Patent application title: Method and apparatus for chemical polishing treatment of wafer

[Claims]

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for chemically polishing a semiconductor wafer.

[0002]

2. Description of the Related Art Conventionally, semiconductor wafers are chemically polished by holding a wafer on a mechanical chuck or a vacuum chuck and spraying a processing liquid and a cleaning liquid onto a surface to be processed .

[0003]

In the conventional chemical polishing treatment of a wafer, a chemical polishing treatment liquid such as nitric acid or hydrofluoric acid adheres to the back side of the treatment surface of the wafer or the back side of the treatment liquid mist .
In the past , taping was applied to the non-processed surface of the wafer as a countermeasure.However, a large amount of labor was required for this taping work. , Which led to higher costs.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a vacuum chuck having a vacuum suction surface at an upper end, a wafer chucking with a processing surface of a wafer facing upward, and a chemical chuck from an upper nozzle. The polishing processing liquid and cleaning liquid are sprayed on the upper surface , and the purging gas is sprayed from the upper peripheral part of the vacuum chuck to the peripheral part of the adsorption surface of the wafer to scatter the chemical polishing liquid and cleaning liquid to the outside of the circumference. To the circumference of the suction surface
It prevents adhesion and mist wraparound .

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a vacuum chuck having a circular suction surface at the upper end and a wafer having a larger diameter than the circular suction surface in a state in which the peripheral portion protrudes from the outer periphery of the vacuum chuck.
Absorbing the treated surface upward, spraying a chemical polishing liquid such as nitric acid or hydrofluoric acid on the upper surface while rotating to perform chemical polishing, and then cleaning by spraying a cleaning liquid such as pure water. from the upper end outer periphery, blowing a purge gas such as nitrogen gas into the circumferential portion of the suction surface of the wafer, a chemical polishing method of processing a wafer to scatter the chemical polishing treatment liquid and cleaning liquid to the outside of the circumference.

Further, an apparatus for carrying out the above-mentioned chemical polishing treatment method for a wafer is provided with a spline formed on the outer periphery, a tubular rotating elevating shaft having an axial hole, and a ball spline bearing having a pulley for transmitting rotation. Thus, the frame is supported upright so as to be able to rotate and ascend and descend on the frame, and a vacuum chuck for adsorbing and holding a wafer to be chemically polished is attached to the upper end of this rotating and elevating shaft.

In this vacuum chuck, a circular suction surface having a smaller diameter than the wafer is formed on the upper surface by opening a plurality of suction grooves, and the suction grooves communicate with a suction center hole penetrating the center of the circle. through the axial through hole of the rotary elevating shaft, together to communicate with the suction pipe leading to the outside of the vacuum pump, the purge gas supplied through the axial through hole of the rotary elevating shaft, the suction surface of the wafer An annular outlet gap that opens obliquely upward at the outer periphery of the upper end of the vacuum chuck for blowing on the circumferential portion, an annular space that communicates with the lower end of the annular outlet gap, and the annular space that communicates with the axial through hole. A purge gas passage is provided.

Further, a filter unit for dust removal communicating with a purge gas communication passage provided at a lower end member of the elevating shaft provided at a lower end of the rotary elevating shaft is attached to a lower end bearing rotatably supporting the lower end member of the elevating shaft. In some cases.

[0009]

Embodiments will be described with reference to the drawings.
Reference numeral 1 denotes a rotary elevating shaft, which has a spline 1a formed of a plurality of vertical grooves on the outer circumference, a shaft through hole 1b, and a tubular spline shaft having a flange 1c formed at an upper end thereof. The two ball spline bearings 2, 2 attached to the frame 13 and arranged in series in the vertical direction are supported so as to be rotatable and vertically movable.

The ball spline bearings 2, 2 are rotatably supported by an outer cylinder 2a mounted on a frame 13 by an outer bearing 2b, and an elevating guide bearing 2d is provided on the inner periphery of the upper and lower ends of the inner cylinder 2c. The balls of the elevating guide bearing 2d are fitted into the plurality of vertical grooves of the spline 1a provided on the outer periphery of the elevating shaft 1, and serve as the elevating guide of the rotatable elevating shaft 1. Is vertically movable with respect to the inner cylinder 2c of the upper and lower two ball spline bearings 2, and is rotatably supported by the outer bearing 2b integrally with the inner cylinder 2c with respect to the outer cylinder 2a.
You .

A pulley 3 is attached to the lower end of the inner cylinder 2c of the lower ball spline bearing 2 of the two ball spline bearings 2 and 2 and driven by an electric motor (not shown) via a belt 3a. The ball of the elevating guide bearing 2d fits into the spline 1a together with the inner cylinder 2c, and the rotary elevating shaft 1 rotates.

Numeral 4 denotes an elevating airtight cylinder, which has a structure in which the upper end of the cylinder is closed, covers the upper end of the rotary elevating shaft 1 and is mounted on a flange 1c at the upper end of the rotary elevating shaft 1. The fixed airtight cylinder 4 attached to the frame 13
a is provided with a confidential seal 4b on the inner periphery of the upper end, and when the elevating and lowering airtight cylinder 4 moves up and down while rotating together with the rotary elevating shaft 1, the airtightness with the outer peripheral portion of the ascending and descending airtight cylinder 4 is maintained. The liquid and the cleaning liquid are prevented from scattering and adhering to the rotating shaft 1 and the ball spline bearing 2.

A lower end member 5 of the elevating shaft is attached to the lower end of the rotary elevating shaft 1. The lower end member 5 of the elevating shaft is connected to a lower end bearing 7 attached to an elevating plate 6 which moves up and down by another elevating means (not shown). The lower shaft member 5 is rotatably supported by two bearings 7a, 7a. The lower shaft member 5 has a shaft through hole 1b of the rotating shaft 1 and a vacuum passage 5a communicating with the outside of the lower shaft bearing 7. A purge gas communication passage 5b communicating with the axial through hole 1b and the outside of the lower end is provided.

[0014] axial through hole 1b to the suction pipe 8 of the rotary elevating shaft 1 is inserted, communicates its lower end to a vacuum passage 5a, the upper
The end is penetrated and fixed to the upper end of the lifting airtight cylinder 4 . The vacuum passage 5a communicates with an external vacuum pump (not shown) via a vacuum pump path 9 connected to the lower end bearing 7. The vacuum pump path 9 includes an electromagnetic valve 9a, and an air suction path 9b for preventing excessive suction is provided in parallel with an air filter 9c and an electromagnetic valve 9d that opens when necessary.

Reference numeral 10 denotes a vacuum chuck, which comprises a lower body 10a and an upper body 10b. The lower body 10a has a concave upper surface except for the peripheral portion of the thick disk, and the upper end of the peripheral portion descends toward the center. An upper body 10b having a substantially cup-shaped outer shape and having a circular suction surface 10c whose diameter is slightly smaller than that of the disk-shaped object W fits into the central concave portion and is joined to the central concave portion. The lower end of the lower body 10a
It is attached to the upper end of an elevating airtight cylinder 4 which covers the upper end of the rotary shaft, and is integrated with the rotary elevating shaft 1.

The upper end of a suction pipe 8 passing through the axial through hole 1b of the elevating rotary shaft 1 is opened in a suction center hole 10d penetrating through the center of the vacuum chuck 10.
A plurality of concentric grooves formed on the circular suction surface 10c and suction grooves 10e formed of radial grooves communicate with each other.

An annular space 10f is provided between the lower body 10a and the upper body 10b at a position close to the outer periphery, and the annular space 10f
An annular gap 10g is formed obliquely upward toward the upper end of the outer periphery so as to communicate with the annular space 10f and the rotary elevating shaft 1
Gas upper passage 10 communicating with the axial through hole 1b
h is formed to communicate the elevating airtight cylinder 4, the lower body 10a, and the upper body 10b.

Reference numeral 11 denotes a filter unit, and the lower end bearing 7
A filter 11a is sandwiched by a filter holding plate 11b, and a purge gas supply path 12 connected to a nitrogen gas container (not shown) is provided at the lower end of the filter unit 11 with an electromagnetic valve 12a. After the nitrogen gas for purging is filtered through the filter 11a, it is provided to the vacuum chuck 10 through the through hole 1b of the rotary elevating shaft 1 through the gas communication hole 5b for purging provided in the lower end member 5 of the elevating shaft. After passing through the purge gas passage 10h into the annular space 10f, the semiconductor wafer W is sucked from the annular blowing gap 10g to the circular suction surface 10c and sprayed obliquely from below on the back surface circumferential portion of the rotating semiconductor wafer W. In addition, the chemical polishing treatment liquid and the cleaning liquid are scattered from the circumference.

Numeral 14 denotes an injection nozzle which moves up and down in synchronism with the elevating of the rotary elevating shaft 1 while always keeping a constant interval with the vacuum chuck 10. FIG.
4 shows a state in which chemical polishing treatment liquid such as nitric acid, hydrofluoric acid or the like is sprayed in a state where it is most lowered with respect to the frame 13 to perform chemical polishing. FIG. Thus, a state in which the cleaning is performed by injecting pure water from the injection nozzle 14 is shown. The above-described injection of the purge gas is operated both during the chemical polishing and during the cleaning.

[0020]

The present invention is embodied in the form described above and has the following effects.

By using a vacuum chuck, the entire outer periphery of the wafer can be held in an open state .
By spraying a purge gas during chemical polishing and cleaning, to scatter the chemical polishing solution and cleaning solution,
It is possible to prevent the chemical polishing treatment liquid and the cleaning liquid from adhering to the lower surface of the disk-shaped object and prevent the mist from flowing around, so that a clean product can be obtained.

The chemical polishing treatment liquid and cleaning liquid to prevent from adhering to the non-abrasive surface, is conventional, non
Taping to the polished surface is not required at all, and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a view showing a state in which a main part of the apparatus of the present invention is subjected to a chemical polishing process with a vacuum chuck being at a lower position.

FIG. 2 is a diagram showing a state in which a main part of the apparatus of the present invention is subjected to a cleaning process in which a vacuum chuck is positioned at a higher position.

FIG. 3 is an enlarged sectional view of a vacuum chuck.

FIG. 4 is a plan view of the same.

[Description of Signs] W Wafer 1 Rotary elevating shaft 1a Spline 1b Shaft through hole 1c Flange 2 Ball spline bearing 3 Pulley 4 Elevating airtight cylinder 4a Fixed hermetic cylinder 4b Hermetic seal 5 Elevating shaft lower end member 5a Vacuum passage 5b Purge gas connection Passage 6 Elevating plate 7 Lower end bearing 8 Suction pipe 9 Vacuum pump path 10 Vacuum chuck 10a Lower body 10b Upper body 10c Circular suction surface 10d Suction center hole 10e Suction groove 10f Annular space 10g Annular discharge gap 10h Purging gas passage 11 Filter unit 11a Filter 11b Filter holding plate 12 Gas supply path for purging 13 Frame 14 Injection nozzle

Claims (3)

[Claims] 1. A vacuum chuck having an upper end with a circular suction surface,
When performing a chemical polishing treatment by injecting a wafer having a diameter larger than that of the circular suction surface in a state in which a peripheral edge of the wafer protrudes from the outer periphery of the vacuum chuck and spraying a chemical polishing liquid or a cleaning liquid on the upper surface while rotating. A chemical polishing process for a disk-shaped object, characterized in that a purge gas is blown from the outer periphery of the upper end of the rotary vacuum chuck to the peripheral portion of the back surface of the wafer to scatter the chemical polishing treatment liquid and the cleaning liquid to the outside of the circumference. Method. 2. A tubular rotary shaft (1) having a spline (1a) formed on its outer periphery and having a shaft hole (1b).
Is supported upright on a frame (13) by a ball spline bearing (2) having a pulley (3) for transmitting rotation so that the frame can be rotated and raised and lowered. A vacuum chuck (10) for holding the wafer (W) to be sucked is attached, and a circular suction surface (10c) having a smaller diameter than the wafer (W) is formed on the upper surface of the vacuum chuck by a plurality of suction grooves (10e). The suction groove is formed by opening a suction center hole (1) passing through the center of the circle.
0d), through the through-hole (1b) of the rotary elevating shaft (1), to the suction pipe (8) connected to the external vacuum pump, and at the same time as the axis of the rotary elevating shaft (1). For blowing a purging gas supplied through the through-hole (1b) to a peripheral portion of the back surface of the wafer (W);
An annular outlet gap (10g) opening obliquely upward at the outer periphery of the upper end of the vacuum chuck (10), an annular space (10f) communicating with the lower end of the annular outlet gap, and the annular space and an axial through hole (1b). Purge gas passage (10
h), a wafer chemical polishing apparatus. 3. A filter unit (11) for dust removal which communicates with a purge gas communication passage (5b) provided in a lower end member (5) of a vertical shaft connected to a lower end of a rotary vertical shaft (1). Lower end bearing (7) for rotatably supporting member (5)
3. The apparatus for chemically polishing a wafer according to claim 2, wherein the apparatus is attached to a wafer.