JPH07221062A - Spin washing machine and method - Google Patents

Abstract

PURPOSE:To prevent pin hole defect from occurring due to the injection of pure water by providing a recessed part which is level with a spin chuck caused by the engagement of a substrate to be treated at a ground spin chuck center and laying out a washing liquid nozzle which opens in a fan outside the spin chuck consisting of a metal with a corrosion-resistant surface. CONSTITUTION:A substrate 1 to be treated is engaged to the recessed part in a spin chuck 2 for leveling and at the same time a washing liquid nozzle 5 is turned into a fan shape where the tip is divided into a plurality of parts. Also, a connection part 7 is provided at a spin chuck shaft 3 where an exhaust port 6 for vacuum chuck is provided and static electricity is discharged with a lower contact resistance. The surface of the spin chuck 2 is exposed to chemical treatment in the etching process of the substrate 1 to be treated so that it should be formed with corrosion-resistant metal. This sort of structure eliminates discharge which is generated in the case of pure-water washing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spin cleaning machine used for cleaning a substrate to be processed, especially a photomask, and a cleaning method therefor.

Information processing apparatuses have been increased in capacity because of the need to rapidly process a large amount of information. As a method for achieving this, electronic parts, particularly semiconductor parts, are increased in capacity by downsizing unit elements. Thus, integrated circuits such as LSI and VLSI have been put into practical use, and there is a tendency toward higher integration.

In these integrated circuits, the minimum pattern width of the conductor lines forming the electronic circuit has reached the sub-micron (sub-micron) level. Therefore, when manufacturing electronic parts, particularly semiconductor parts, dust adheres to them. In order to eliminate the occurrence of defects, the main treatment is performed in a clean room, and the production is automated as much as possible. In addition, the water used for washing was cation and anion removed by an ion exchange resin. Pure water is used.

[0004]

2. Description of the Related Art A thin film forming technique and a photolithography technique (photolithography) are frequently used for manufacturing a semiconductor device, and a photomask is used for the photoetching technique.
That is, after forming a thin film on a semiconductor substrate (wafer) by a vacuum vapor deposition method or a sputtering method, a resist is coated on the thin film, and this is irradiated with ultraviolet rays through a photomask to selectively irradiate the resist. When a positive resist is used, the exposed part becomes soluble in the developing solution, and when a negative resist is used, the exposed part becomes slightly soluble in the developing solution. Dry etching or wet etching is performed as a mask, whereby a fine pattern is formed.

Here, a photomask is an original plate for forming a pattern in the formation of an integrated circuit, and is generally formed by selectively etching a metal thin film made of chrome (Cr) formed on a quartz substrate or a glass substrate. However, the existence of fine defects is not allowed, and therefore, a spin cleaning machine is used for etching and cleaning the substrate after the development processing.

That is, conventionally, as shown in FIG. 2, a substrate 1 to be processed (in this case, a Cr-coated quartz substrate to which a resist is selectively adhered) 1 after development processing is spin chucked.
In the state in which the substrate 1 to be processed is vacuum-sucked through the exhaust pipe provided on the spin chuck shaft 3, the spin chuck 2 is rotated at a high speed by a motor (not shown), and in this state, the cleaning liquid nozzle 4 After that, the etching liquid is jetted onto the substrate to be processed 1 to perform selective etching, and then the etching liquid is switched to pure water and jetted onto the substrate to be processed 1 for spin cleaning.

The feature of this spin cleaning machine is the cleaning liquid nozzle 4
Since the etching solution or pure water is spouted from the substrate, the etching efficiency or cleaning efficiency is high. The substrate 1 to be processed rotates at high speed to scatter the etching solution or pure water from the substrate surface, resulting in excellent drying efficiency. It is that.

However, pure water is jetted from the cleaning liquid nozzle 4,
Further, when the substrate 1 to be processed is made of an insulating material, static electricity is charged and discharged, which causes a problem that a pinhole defect occurs at a discharge position.

That is, pure water has a high resistivity of 28 to 18 (MΩ · cm) at room temperature of 20 to 25 ° C. Therefore, when the pure water is jetted from the cleaning liquid nozzle 4, friction with the nozzle 4 and air are caused. Static electricity is generated due to friction with the photomask. On the other hand, when a fine pattern made of Cr is independently formed on the insulating substrate like a photomask, if the charge amount increases and exceeds, for example, 500 V, the pattern There is a problem that a discharge is generated between them and a pinhole defect is generated in the pattern at the discharge location.

Therefore, in order to avoid this phenomenon, conventionally, carbon dioxide gas (CO ₂ ) is dissolved in pure water, or ozone (O ₃ ) is dissolved to lower the resistivity (for example, JP-A-3-41729). A method has been proposed in which pure water is heated to about 50 ° C. to reduce the resistivity to several MΩ · cm so that static electricity is hardly generated (Japanese Patent Laid-Open No. 61-156740).

However, these methods are not preferable because they lower the purity of pure water and require extra man-hours. Therefore, a simple method to replace this has been desired.

[0012]

The cleaning of the substrate to be processed can be performed efficiently by using a spin cleaning machine. However, when pure water is used for cleaning, the resistivity of pure water is reduced. Since the size is large, there is a problem in that a dielectric breakdown due to electrification occurs on the substrate to be processed and a pinhole defect occurs in the pattern.

If the substrate to be processed has a large area,
There is a problem that it is necessary to treat the surface quickly and uniformly, and if the flow rate of pure water is increased to achieve this purpose, the number of electrostatic breakdown increases and physical damage due to the impact of running water occurs. There is. Therefore, the practical application of a cleaning method that does not cause pattern damage is an issue.

[0014]

SUMMARY OF THE INVENTION The above problem is that the spin chuck has a recess at the center thereof to be fitted with a depth equal to the thickness of the substrate to be processed, and the spin chuck shaft is grounded. Using a spin cleaning machine with multiple fan-shaped nozzles for cleaning the substrate to be processed outside the chuck, the substrate surface of the substrate to be processed placed in the central recess of the spin chuck is flat and flat with no spin chuck surface. It is possible to solve the problem by adopting a method in which the cleaning liquid supplied from the plurality of nozzles on the outer side of the spin chuck hits the metal plate on the outer peripheral portion of the spin chuck and is then supplied to the substrate to be processed for cleaning. .

[0015]

Function: Pure water has a high resistivity, so that when it is ejected from the cleaning liquid nozzle, it is charged by friction with the nozzle and air. Therefore, the inventor does not directly jet and wash pure water onto the substrate to be processed as in the conventional case, but first collides with the spin chuck portion outside the substrate to be processed which is vacuum-adsorbed and is rotating, This problem has been solved by cleaning the surface of the substrate to be uniformly spread and flowing.

Here, in order for the pure water that has hit the outer peripheral portion of the spin chuck to flow evenly over the surface of the substrate to be processed for efficient cleaning, the substrate to be processed must be fitted to the spin chuck. Therefore, it is necessary that the water flow is not obstructed, pure water is dispersed and flows from the cleaning liquid nozzle, and static electricity charged on the spin chuck is quickly released.

Therefore, the spin cleaning machine according to the present invention is shown in FIG.
As shown in FIG. 3, the substrate 1 to be processed is fitted into the recess in the spin chuck 2 to form the same surface, the cleaning liquid nozzle 5 is formed into a fan shape having a plurality of branched tips, and the exhaust port 6 for the vacuum chuck is provided. The contact portion 7 is attached to the spin chuck shaft 3 provided.
Is provided to discharge static electricity with a contact resistance as low as possible.

The surface of the spin chuck needs to be formed of a corrosion-resistant metal because it is subjected to chemical treatment in the etching process of the substrate to be treated. In this case, it is possible to eliminate the discharge that occurs.

[0019]

[Example] Cr was formed to a thickness of 1000 Å by a sputtering method on a quartz substrate having a size of 6 inches square and a thickness of 0.25 inch, and a resist was spun on the Cr film to a thickness of 0.5 μm. The coated substrate was subjected to selective exposure of ultraviolet rays for forming a reticle to obtain a substrate to be processed.

This substrate to be processed was mounted on the spin chuck 2 of the spin cleaning machine shown in FIG. Here, the surface of the spin chuck 2 made of stainless steel is coated with titanium (Ti) to improve the corrosion resistance. Further, a carbon brush is configured to come into contact with the contact portion 7 of the spin chuck shaft 3 and is grounded.

Further, the cleaning liquid nozzle 5 has its tip branched into three, and the etching liquid and pure water are distributed in a fan shape, and after hitting the outer peripheral portion of the spin chuck 2, they are evenly distributed on the substrate 1 to be processed. It is configured to scatter due to centrifugal force after flowing into.

Next, in the etching process, while the spin chuck 2 is rotated at a rotation speed of 500 rpm, an aqueous solution of cerium ammonium nitrate [NH ₄ Ce (NO ₃ ) ₆ ] is supplied for 45 seconds to etch Cr. Switch to pure water, supply pure water at the same number of revolutions for 60 seconds to rinse, and finally change the number of revolutions.
It was spun at 1000 rpm and spun for 60 seconds to dry. Next, after removing the resist, microscopic observation of the reticle thus formed showed no pinhole defects.

[0023]

By implementing the present invention, the occurrence of pinhole defects due to the injection of pure water can be eliminated, and the quality of the photomask can be improved.

[Brief description of drawings]

FIG. 1 is a plan view of a spin chuck according to the present invention (A).
It is a side sectional view (B).

FIG. 2 is a side sectional view of a conventional spin chuck.

[Explanation of symbols]

 1 substrate to be processed 2 spin chuck 3 spin chuck shaft 4,5 cleaning liquid nozzle

Claims (2)

[Claims] 1. A spin chuck (2), a drive unit for rotating the spin chuck (2) at a high speed, and a cleaning liquid nozzle (4) for supplying a cleaning liquid to a substrate (1) to be processed on the spin chuck (2). A spin cleaning machine comprising: a spin chuck (2) having a recessed portion (8) flush with the substrate (1) to be processed and fitted with the substrate (1) to be processed, and having a corrosion-resistant surface. It is made of metal, the spin chuck (2) is grounded, and
A spin cleaning machine characterized in that a cleaning solution nozzle (5) spread in a fan shape is arranged on the outer side of the spin chuck (2) so that the cleaning solution discharged onto the outer periphery of the spin chuck (2) hits. 2. A substrate (1) to be processed is etched by supplying an etching liquid from a cleaning liquid nozzle (5) outside the spin chuck (2), and then deionized water is supplied for cleaning. The etching liquid and the pure water are discharged from the cleaning liquid nozzle (5) in a fan shape, hit the metal plate on the outer peripheral portion of the spin chuck (2), and then are supplied to the substrate (1) to be processed. Spin cleaning method.