JP2823019B2 - Pure water vapor drying method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] The present invention relates to a method of cleaning and drying a wafer or a glass substrate used in a semiconductor device, and more particularly to a method of drying these objects to be cleaned using pure water. The purpose is to obtain a pure water vapor drying method using pure water, which is free of such danger and has high-purity washing and drying quality, and is easily and inexpensively available. While boiling the pure water at the top and guiding the pure water vapor to the upper part of the container, the air in the container is evacuated from the lower part of the container and the container is filled with pure water vapor,
Then, a pure water vapor drying method is characterized in that the object to be cleaned in the container is dried by lowering the temperature in the container and moving the layer of pure water vapor downward in the container.

[Industrial applications]

The present invention relates to a method of cleaning and drying a wafer or a glass substrate used in a semiconductor device, and more particularly to a method of drying these objects to be cleaned using pure water.

2. Description of the Related Art In various industries, there is a demand for safe and high-performance washing and drying without causing a risk of explosion or environmental pollution. In particular, in the recent semiconductor industry,
A high-performance cleaning technique is required for cleaning a wafer, and the final cleaning and drying technique is particularly important, and it is necessary to prevent dust and the like from adhering during drying. Further, there is a possibility that various organic solvents having a risk of adversely affecting the environment can no longer be used for cleaning from the viewpoint of environmental protection. Therefore, it is required to establish a safe and high-performance technique for drying these objects to be cleaned.

[Conventional technology]

Conventionally, as a drying method at the final stage of a wafer used for a semiconductor element, there have been methods such as freon vapor, IPA vapor, spin drying, natural drying, and dry gas blowing. Each of these methods has advantages and disadvantages. Among them, drying of organic solvents by vapor is widely used. This is because the organic solvent has a large molecular polarity and the vapor density is higher than the air density, so that a vapor zone can be easily formed and a high cleaning effect can be obtained. However, although the washing / drying method using an organic solvent can provide a high degree of washing, use restrictions will be stricter in the future because of air pollution, flammability, carcinogenicity and the like. Further, at present, other cleaning / drying methods cannot obtain a high degree of cleaning as high as vapor drying of an organic solvent.

[Problems to be solved by the invention]

As described above, the use of vapor drying with an organic solvent will be restricted in the future, and the cost for solvent recovery equipment and safety measures will increase, and the development of alternative chemicals will also require large costs.

Therefore, the present invention provides a pure water vapor drying method using pure water that is free from dangers such as organic solvents and can be obtained with high-purity washing and drying qualities and that can be obtained easily and inexpensively. Aim.

[Means for solving the problem]

To solve such a problem, according to the present invention,
The pure water is boiled below the closed container on the upper side to guide the pure water vapor to the upper part of the container, and the air in the container is evacuated from the lower part of the container to fill the container with pure water vapor. A method for drying pure water vapor, characterized in that the object to be cleaned is dried by lowering the temperature in the container and moving the layer of pure water vapor downward in the container.

[Action]

After the object to be cleaned is placed in the container, the container is filled with high-temperature pure water vapor as described above. Since the object to be cleaned is initially in a wet state and has a lower temperature than the vapor in the container, condensed droplets adhere to the surface of the object to be cleaned and wash away dirt.
When the temperature of the object to be cleaned rises, the droplets no longer adhere and become dry. At this time, the temperature in the container is lowered, the layer of pure water vapor is moved downward in the container, and the object to be cleaned is taken out from the upper portion of the container.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a principle diagram of a pure water vapor drying method of the present invention. A pure water reservoir 2 is provided below the container 1 whose upper side is sealed, and a heater 3 is provided below the pure water reservoir 2. When the pure water is heated and boiled by the heater 3, the pure water vapor rises and is led to the upper part of the container 1. The air in the container 1 is discharged from the lower part of the container 1 through the filter 4. Thus, a pure water vapor layer is formed in the container 1 from above. A spiral cooling water conduit 5 is provided along the inner wall of the container 1, and cooling water is supplied to the cooling water conduit 5. Thereby, the inside of the container 1 is cooled, so that the pure water vapor layer moves downward in the container 1. In this process, the object to be cleaned 10 in the container 1 is dried.

FIG. 2 shows an embodiment of the pure water vapor drying method of the present invention. This embodiment is used in a final cleaning / drying step of, for example, a semiconductor wafer or a glass substrate. At the top of the container 1, there is a lid 12 which can be opened and closed.
The object to be cleaned 10 mounted on 13 can be carried into and out of the container 1 while the lid 12 is open. The inside of the container 1 is divided into an upper portion and a lower portion by a stainless steel wire net 14, for example. At the upper part of the container 1, a conduit 5 similar to the cooling water conduit 5 of FIG. 1 is provided spirally along the inner wall of the container 1. However,
In addition to supplying cooling water to the conduit 5 to cool the container, high-temperature (for example, about 140 ° C.) steam can be supplied to heat the upper region of the container 1. Another cooling / heating pipe 15 is provided in the lower part of the container 1. This piping 15
Also, cooling water or high-temperature (for example, about 140 ° C.) steam can be supplied to cool and heat the lower region of the container 1.
A number of cooling / heating fins 16 are attached to the pipe 15.
As shown in FIG. 1, a lower portion of the container 1 has a portion that is communicated with the outside via a filter 4. Container 1 as in FIG.
There is a pure water reservoir 2 and a heater 3 below the water reservoir. In this embodiment, an overflow reservoir receiving water overflowing from the pure water reservoir 2 or water condensed and dropped in the container 1 is further provided around the pure water reservoir 2. 17
The pure water in the overflow reservoir 17 is returned to the pure water reservoir 2 by the pure water circulation pump 18 and the filter 19.

The drying process according to the embodiment of FIG. 2 is as follows. First, with the lid 12 on the upper portion of the container 1 closed, pure water is heated by the heater 3 to a boiling state, and a vapor layer is formed on the upper portion of the container 1. Cooling water has not yet flowed into the coiled conduit 5. Immediately before the carrier 13 containing the object 10 to be washed is placed in the container 1, cooling water is supplied to the pipes 5 and 15 to remove the vapor layer in the upper region of the container 1. In this state, the lid 12 on the upper part of the container 1 is opened, and the carrier 13 is put into the container 1 and the wire mesh is
Set on 14.

When the lid 12 is closed and the supply of the cooling water to the pipes 5 and 15 is stopped, the pure water vapor layer rises again. As a result, the wafer 10 to be cleaned is cleaned and dried as described above.
At this time, in order to promote the rise of the pure water vapor, the cooling water accumulated in the pipes 5 and 15 is pushed out with air, or the high-temperature (for example, about 140 ° C.) steam is flowed as described above to immediately cool the cooling water. Extrude and heat vessel 1.

After the drying, when taking out the carrier, the cooling water is flown again into the pipes 5 and 15 to remove the pure water vapor in the container, and then the cover 12 is opened and the carrier 13 is taken out.

〔The invention's effect〕

As described above, according to the present invention, by performing drying using pure water vapor, there is no problem such as explosion risk, air pollution and carcinogenicity as compared with the conventional organic solvent vapor drying method. Also, there is no need for cost for solvent recovery and disposal. Further, since pure water having a higher purity than the solvent can be easily obtained, a high cleaning effect can be expected.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing the principle of the present invention, and FIG. 2 is a diagram showing the configuration of an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1 ... Container, 12 ... Opening / closing lid, 2 ... Pure water reservoir, 13 ... Carrier, 3 ... Heater, 14 ... Wire mesh, 4 ... Filter, 15 ... Cooling / heating piping, 5 ... Cooling・ Heating conduit, 16 fins, 10 objects to be cleaned, 17 overflow reservoir, 18 pure water circulation pump, 19 filters.

Claims (1)

(57) [Claims] 1. Boiling pure water below a closed container (1) to guide pure water vapor to an upper portion of the container, and bleeding air from the lower portion of the container to remove the air from the container. Pure water characterized by drying the object to be cleaned (10) in the container by filling the container with pure water vapor and then lowering the temperature in the container and moving the layer of pure water vapor downward in the container. Vapor drying method.