JP3012571B2 - Cleaning equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a cleaning device,
In particular, it relates to a cleaning device using high-pressure water.

[0002]

2. Description of the Related Art When cleaning a photomask or a wafer used in the manufacture of a semiconductor device with pure water, pure water is sprayed from a nozzle at a high pressure to spray the wafer surface. This pure water has a resistivity of 15 MΩ · cm or more.
When sprayed on the wafer surface at a pressure of 100 kg · cm ^-2 , static electricity is generated due to the contact of the insulating film such as a silicon oxide film on the wafer surface with pure water, and the wafer surface is charged to have a potential of several kilovolts or more. . The static electricity causes a problem that the characteristics of the semiconductor device deviate from the expected ones or are broken. For example, if pure water cleaning is performed after the formation of the MOS transistor, the gate insulating film is likely to be broken.

As a first measure, carbon dioxide is bubbled, carbonic acid (H ₂ CO ₃ ) is dissolved in pure water to make it weakly acidic, and its resistivity is made about 100 kΩ · cm.
Techniques for suppressing generation of static electricity have been used. As a result, the voltage due to charging can be reduced to several tens to several hundreds of volts. However, it is difficult to prevent dielectric breakdown when the thickness of the gate oxide film is reduced to 15 nm or less with high integration of semiconductor devices. It is.

As a second measure, there is a method of spraying pure water at a high pressure in an ion atmosphere.

[0005] Of course, it is also possible to combine the first method and the second method.
No. 26 describes a method of performing wafer cleaning not only in bubbling of carbon dioxide but also in an ion atmosphere. This is a technique for preventing an increase in the wear of a grindstone (blade) in a dicing step for separating a wafer into single pieces when the concentration of carbonic acid is increased. Next, it is extracted from this publication. However, reference numerals and some terms have been changed.

As shown in FIG. 4, a wafer to be cleaned 1 is vacuum-adsorbed on a chuck table 2. The chuck table 2 is a motor 3 for rotating the chuck table.
Rotated by For cleaning the wafer (1), high-pressure water 6 is introduced from the outside, and the jet 2 is jetted through a jet nozzle 9.
When it becomes 0 and hits the surface of the wafer (1), foreign substances such as silicon on the wafer surface are removed. At this time, since the surface of the wafer (1) comes into contact with the jet 20 of high-pressure and high-resistance pure water containing CO ₂ , positive charges accumulate on the surface. As for the ions 19, positive ions and negative ions flow from the external ion generator 18 through the ion blowing nozzle 17 toward the surface of the wafer (1). This ion 19
Thus, the positive ions accumulated on the surface of the wafer (1) are neutralized by the negative ions of the ions 19. The ion balance in the atmosphere can be maintained by setting the amount of generated ions 19 to be larger than the accumulated charges on the surface of the wafer (1). The shape of the ion blowing nozzle 17 is formed in the cover 4 in a ring shape, and has an infinite number of cylindrical holes.
N ₂ injection nozzle 21 is intended to blow the a N ₂ wafer (1) surface when dried wafer (1) the surface after the jet 20 wash CO ₂ containing pure water. Ion 19 is CO
From washing with ₂ containing the jet 20 of the pure water N ₂ injection nozzle 2
This occurs in all the states up to the drying of the wafer (1) surface by No. 1. The exhaust duct 5 is provided for exhausting mist and N ₂ during cleaning by the jet 20.
The ion hose 16 is a connecting pipe from the ion generator 18 to the ion blowing nozzle 17. The pure water connection pipe 22 is a pipe for guiding the external high-pressure water 6 to the jet nozzle 9. N ₂ 23
Is supplied from outside. N ₂ connecting pipe 24 connects N ₂ 23 to N
_{2 This} is a tube leading to the injection nozzle 21.

[0007]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Application Laid-Open No. 3-1 is disclosed.
It is clear that the technique described in Japanese Patent No. 31026 can be used for photomask and wafer cleaning in general, and can be said to be an excellent technique with versatility.

However, while the entire wafer is exposed to the ion atmosphere, the jet of water is local, and the generation of electric charges also becomes local. A large amount of ions are generated to sufficiently neutralize the electric charges while maintaining ion balance. I have to do it. In addition, it is difficult to make the ion density uniform on an object to be cleaned such as a wafer. Therefore, it is difficult to reliably neutralize the charges on the entire surface of the object to be cleaned. Such a problem becomes even greater as the diameter of the wafer increases.

SUMMARY OF THE INVENTION An object of the present invention is to provide a cleaning apparatus which can clean the entire surface of an object to be cleaned while reliably neutralizing electric charges.

[0010]

According to the present invention, there is provided a cleaning apparatus comprising:
A nozzle that injects water from the inner pipe of the heavy pipe and blows out an ion-containing gas from between the outer pipe and the inner pipe of the double pipe, means for placing the article to be washed, and a relative position between the nozzle and the article to be washed. in the cleaning and means for scanning against water and ion-containing gas is injected from the nozzle to the surface of the object to be cleaned by changing the position, the tip portion of the nozzle
The outer tube and the inner tube are respectively a first conductive member and a second conductive member.
Of the first conductive member, and is guided to the inner wall of the first conductive member.
An electrically conductive projection is provided, and the first conductive member and the second conductive member are provided.
Means for applying voltage and discharging between conductive members
It is something that has been damaged .

[0011] Also, it is possible to form the conductive projections of a refractory metal or a refractory metal silicide. Furthermore, before
A static electricity sensor may be provided at the tip of the nozzle to control the voltage value according to the detected static electricity.

Instead of exposing the entire object to be cleaned to an ion atmosphere, the density is further increased by discharging around the tip of the nozzle.
It is possible to blow the ions.

[0013]

Referring to the DETAILED DESCRIPTION OF THE INVENTION Figure 1, reference of the present invention
The cleaning apparatus of the example includes a chuck table 2 for vacuum-sucking the object to be cleaned 1 and a chuck table rotating motor 3 for rotating the chuck table 2.

The nozzle is a double pipe, and high-pressure water 6 supplied from a pressure pump (not shown) is injected from the tip through an inner pipe 9A, and forms an outer pipe 10- which forms a double pipe with the inner pipe 9A. An ion generator (not shown) (corresponding to the ion generator 18 of Japanese Patent Application Laid-Open No. Hei 3-131,026) is connected to the blower pipe 10-2 connected to the gas generator 1 through an ion-containing gas 8a (N ₂ gas containing positive ions and negative ions or Dry air) is supplied and blows out from a gap between the outer tube 10-1 and the inner tube 9A (ion-containing gas 8b). A spacer can be locally inserted between the outer tube and the inner tube so that the gap is substantially constant. The outer shape, dimensions, and number of the spacers are selected accordingly so as to minimize the flow of the ion-containing gas. The nozzle is held by a mechanism (not shown) and is movable substantially parallel to the surface of the object to be cleaned, here, the wafer.

The resistivity is 100 k by bubbling of CO _2.
Pure water containing CO ₂ (high-pressure water 6) of about Ω · cm is supplied to the inner tube 9A, and 50 to 100 kg · c from the tip thereof.
^{Injected at} a pressure of m- ² . This cleaning pressure is 80 to 90 kg · c in consideration of damage to the device and removal efficiency of particles (foreign matter and dust) when cleaning the wafer.
It is preferable to set m- ² .

Next, the cleaning of a wafer using this cleaning apparatus will be described.

A wafer on which an MOS transistor is formed and an interlayer insulating film is deposited (before a through hole is formed in the interlayer insulating film) is used as a cleaning object 1 as a chuck table 2.
Vacuum adsorption. The chuck table 2 is rotated by a chuck table rotation motor 3. The cleaning of the wafer (1) is performed by the CO injected from the tip of the inner tube 9A.
_This is performed by colliding a jet 20 of pure water containing ₂ with the wafer (1). Particles attached to the surface of the interlayer insulating film on the wafer are removed, but at the same time, positive charges are accumulated in the interlayer insulating film. This positive charge is transferred to the inner tube 9A.
And the outer tube 10-1 is neutralized by negative ions in the ion-containing gas 8b blown out from the gap between the outer tube 10-1 and the outer tube 10-1. By increasing the density of positive ions and negative ions in the ion-containing gas 8b and the amount of air blow, it is possible to avoid new charging due to the ion-containing gas in which negative ions have been reduced by neutralization. That is, the ion balance can be easily maintained.
When the nozzle is moved, the entire surface of the wafer can be washed sequentially, in conjunction with the rotation of the wafer.However, the positive charges accumulated in the interlayer insulating film where water is colliding are neutralized immediately after the occurrence. You. In addition, since the ion-containing gas is locally sprayed near the place where the charge is generated, the flow rates of the positive ions and the negative ions per unit area can be sufficiently obtained,
Neutralization occurs quickly. Accordingly, the neutralization of the electric charges can be secured over the entire surface of the wafer while maintaining the ion balance, and the wafer can be cleaned.

The water sprayed on the wafer is shaken off by the centrifugal force of the wafer rotation, hits the cover 4, and then discharged by the exhaust duct 5 together with mist, N ₂ gas or air. After the washing is completed, the spraying of water can be stopped to dry.

Even when the thickness of the gate oxide film of the MOS transistor was set to 15 nm, dielectric breakdown could be prevented.

FIG. 2A is a schematic view showing a first embodiment of the present invention, and FIG. 2B is an enlarged sectional view of a portion corresponding to the line AA in FIG. 2A.

In this embodiment, an outer tube is provided at the tip of the nozzle.
10-1A and the inner tube 9B are each an aluminum cylinder 1
0-1Aa (first conductive member) and aluminum cylinder 9
Ba(Second conductive member), and made of aluminum cylinder 10
-1Aa on the inner wall of a plurality of conductive protrusions 11 (high melting point metal
Or a refractory metal silicide such as WSix, x=
2). Outer tube 10-1
Parts other than aluminum cylinder 10-1Aa of A and inner tube
The part other than the aluminum cylinder 9Ba of 9B is made of an insulator.
Shall be. The aluminum cylinder 9Ba of the inner tube is grounded
The outer tube 10-1Aa is grounded by the wiring 12,
Connected to an AC voltage power supply 7 by a line 13 and having a frequency of 50 to 6
A voltage of 0 Hz and a voltage of 4 to 7 kV is supplied. Protrusion 11
Occurs between the tip of the aluminum cylinder and the aluminum cylinder 9Ba.
Since positive and negative ions are generated,Reference exampleCompare to
Then, the ions of the ion-containing gas blown out from the nozzle
There is an advantage that the density of the particles can be easily increased.

FIG. 3 is a schematic diagram showing a second embodiment of the present invention.

This embodiment is different from the first embodiment in that an inductive amplification type electrostatic quantity sensor 14 is attached to an aluminum cylinder 10-1Aa insulated from the aluminum cylinder 10-1Aa.
Connected to the AC voltage power supply 7A. However, when a high voltage is applied to the aluminum cylinder 9Ba of the inner tube,
The aluminum cylinder 10-1Aa of the outer tube is preferably grounded. The AC voltage power supply 7A adjusts the voltage value according to the detected amount of static electricity. When there is unevenness on the surface of the wafer, the amount of static electricity generated by friction with water varies depending on the location, but by generating ions to match the amount of static electricity, insufficient ion density can be more reliably prevented. It is very advantageous. The unevenness differs depending on the type of semiconductor device formed on the wafer or each process. According to this embodiment, any of them can be properly dealt with.

As described above, the case where the resistivity is lowered to about 100 kΩ · cm by bubbling CO ₂ into pure water to clean the wafer on which the MOS transistor is formed has been described. Can be changed accordingly.

[0025]

As described above, the nozzle is formed as a double tube, and a conductive projection is provided at the tip of the conductive member.
And water is sprayed from the inner pipe and released from between the outer pipe and the inner pipe.
By discharging the ion-containing gas whose density has been further increased by electricity and scanning it against the surface of the object to be cleaned, the electric charge on the surface of the object to be cleaned due to friction between water and the object to be cleaned is neutralized in the vicinity of the generation location. Therefore, it is possible to easily clean the entire surface of the object to be cleaned while ensuring ion balance.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a reference example of the present invention.

FIG. 2 is a schematic view showing a first embodiment of the present invention (FIG.
FIG. 2A is an enlarged cross-sectional view of a portion corresponding to line AA in FIG. 2A (FIG. 2B).

FIG. 3 is a schematic diagram showing a second embodiment of the present invention.

FIG. 4 is a schematic view showing a conventional example.

[Explanation of symbols]

1 the cleaning object 2 chuck table 3 chuck table rotating motor 4 cover 5 an exhaust duct 6 high-pressure water 7, 7A AC voltage power source 8 ion-containing gas 9 jet nozzle 9A, 9B inner pipe 10-1 outer tube 10-2 blower tube 11 projection 12 ground line 13 high pressure lines 14 static weight sensor 15 static quantity sensor wiring 16 ions hose 17 ion blasting nozzle 18 ion generator 19 ions 20 jet 21 N ₂ pure water connecting the injection nozzle 22 pipes 23 N ₂ 24 N ₂ connected tube

Claims (3)

(57) [Claims] 1. A nozzle for injecting water from an inner pipe of a double pipe and blowing out an ion-containing gas from between an outer pipe and an inner pipe of the double pipe, means for placing an object to be cleaned, and the nozzle Means for scanning the surface of the object to be cleaned by applying water and an ion-containing gas ejected from the nozzle by changing a relative position of the object to be cleaned ,
At the tip of the nozzle, the outer tube and the inner tube each
An electrically conductive member and a second electrically conductive member;
A conductive protrusion is provided on an inner wall of the conductive member;
A voltage is applied between the conductive member and the second conductive member to be released.
A cleaning device comprising a means for charging . 2. The method according to claim 1, wherein the conductive projection is made of a high melting point metal or a high melting point metal.
The cleaning apparatus according to claim 1, wherein the cleaning apparatus is made of point metal silicide. 3. A static electricity sensor at the tip of the nozzle.
To control the voltage value according to the amount of static electricity detected.
3. The cleaning device according to claim 1, further comprising a step.