JP2834795B2 - Method of cleaning and drying articles using water - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The method for washing and drying an article using water according to the present invention is used when washing an integrated circuit or the like.

(Conventional technology and its problems) In the semiconductor industry, when cleaning integrated circuits,
Currently, Freon is used as a cleaning solution.

However, there is a possibility that CFCs may destroy the ozone layer, such as the possibility of destruction of the ozone layer.Therefore, regulation of its use has been studied in recent years, and some regulations have been implemented. .

For this reason, alternatives to chlorofluorocarbons have been studied, but the possibility that some adverse effects on the global environment cannot be ruled out by the alternatives, and water (ultra pure water or It is desired to establish a technique for cleaning integrated circuits and the like using ultra-pure water.

However, since the latent heat of vaporization of water (539 cal / g) is significantly higher than the latent heat of vaporization of chlorofluorocarbons (39 cal / g), it has been necessary to clean water, such as integrated circuits, and other items that are extremely resistant to contamination by water. It was considered difficult to do.

In other words, when the surface of the object to be cleaned is cleaned with a cleaning solution such as water or chlorofluorocarbon, the cleaning solution adheres to the surface of the object to be cleaned. Different things are inevitable.

When the surface of the object to be cleaned is dried by evaporating the cleaning solution from a state in which a layer of the cleaning liquid having a different thickness is partially formed on the surface of the object to be cleaned, Unless the entire surface is dried without a time lag,
Dry unevenness occurs on the surface.

When CFC having a small latent heat of vaporization is used as the cleaning liquid, the drying of the thick and thin portions of the cleaning liquid is performed almost simultaneously, and the unevenness on the surface of the object to be cleaned may cause a practical problem. Although it does not occur, when water with a large latent heat of evaporation is used as the cleaning liquid, the drying of the thick part of the cleaning liquid is delayed as compared with the drying of the thin part, and dust and the like are formed on the part where the cleaning liquid layer is thick. , And this portion becomes dirty, so-called uneven drying is likely to occur.

In order to prevent the occurrence of uneven drying, to uniform the thickness of the water film on the surface of the object to be cleaned, if air is blown on the surface of the wet object to be cleaned, the air blown part will be dried. However, drying unevenness occurs.

The method of washing and drying an article using water according to the present invention overcomes the disadvantages described above.

(Means for Solving the Problems) The method for washing and drying an article using water of the present invention comprises the following first to third steps (a) to (c). .

(A) After storing an object to be cleaned in a sealable cleaning container,
In this cleaning container, the surface temperature (for example, 20
(About 90 ° C.) or higher (for example, 90 to 100 ° C.), and steam (ultra-pure water or made by evaporating ultra-pure water) is sent in, and the water vapor is condensed on the surface of the object to be cleaned. The first step of humidifying and cleaning the surface of the object to be cleaned.

(B) After the first step, a high-temperature, high-humidity gas having a humidity of almost 100% (e.g., dust or the like is filtered through a high-density filter) on the surface of the object to be cleaned wet with the condensed water. The second step of thinning the water film on the surface of the object to be cleaned by blowing air or nitrogen.

(C) After the second step, the pressure in the cleaning vessel is reduced by, for example, discharging the gas in the cleaning vessel with a vacuum pump to evaporate a thin water film adhered to the surface of the object to be cleaned. Three journeys.

(Operation) By the method of cleaning and drying an article using water of the present invention configured as described above, the surface of an object to be cleaned such as an integrated circuit is humidified and cleaned, and further dried. Since the surface of the object to be cleaned is cleaned well and the thickness of the water film on the surface of the object to be cleaned is made uniform, uneven drying is less likely to occur.

That is, in the first step, when steam having a temperature sufficiently higher than the surface temperature of the object to be cleaned is fed, the water vapor condenses on the surface of the object to be cleaned, and water generated by the condensation is removed. When flowing down the surface of the object to be cleaned, dirt adhering to the surface of the object to be cleaned is washed away, and the object to be cleaned is humidified so that subsequent drying is performed efficiently.

The installation direction of the object to be cleaned is appropriately determined in order to efficiently perform the washing with the condensed water as described above. For example, in the case of a plate-shaped object to be cleaned such as a semiconductor wafer for manufacturing an integrated circuit, Each object to be washed is suspended in the vertical direction with a space between each other in the horizontal direction.

After the dirt attached to the surface of the object to be cleaned has been washed out as described above, the process proceeds to the second step, and the surface of the object to be cleaned wet with condensed water is almost 10
At 0%, a gas having a temperature as high as the surface temperature of the object to be cleaned is blown. However, it goes without saying that this gas passes through a high-density filter such as an ultra filter to remove dust and the like having a size that is harmful to practical use, and is of course a clean gas.

By blowing gas on the surface of the object to be cleaned, the water film adhered to the surface of the object to be cleaned is smoothed (thick portions of the water film are blown off), and the water film adhered to the surface of the object to be cleaned is removed. The thickness is thin and averaged.

The direction in which the gas is blown is determined as appropriate according to the surface shape of the object to be cleaned. However, in the case of a plate-like object to be cleaned such as a semiconductor wafer as described above, the upper part of each object to be cleaned suspended vertically is suspended. Then, by blowing gas downward, an excess portion (water existing in the portion where the water film is thickened) of the water film attached to the surface of each object to be cleaned is flushed downward.

As described above, the thickness of the water film adhered to the surface of the object to be cleaned is thinned and averaged by the spraying of the high humidity gas, but the sprayed gas has a high humidity close to 100%. The surface of the object to be cleaned does not dry, because it is a high temperature that is close to the surface temperature of the object to be cleaned
The surface of the object to be cleaned is partially dried with the blowing of the gas, and the surface of the object to be cleaned does not have uneven drying.

As described above, when the thickness of the water film attached to the surface of the object to be cleaned is reduced and averaged, the process proceeds to the next third step, and the gas in the cleaning container is discharged by a vacuum pump or the like. Reduce the pressure in the cleaning vessel.

As the pressure in the cleaning container storing the object to be cleaned decreases, the boiling point of water decreases, and water attached to the surface of the object to be cleaned evaporates.

At this time, since the thickness of the water film adhered to the surface of the object to be cleaned is thin and is averaged over the entire surface, the water film can be reduced in a short time as the pressure inside the cleaning container decreases. In addition, evaporation is completed almost simultaneously on the entire surface of the object to be cleaned, and the surface of the object to be cleaned does not have unevenness due to drying.

When a gas is blown from above to thin a water film adhered to the surface of a plate-shaped object to be cleaned such as a semiconductor wafer, a relatively large amount of water tends to adhere to the lower edge of the object to be cleaned, For example, since the edge portion of the semiconductor wafer is an unnecessary (discarded) portion, even if drying unevenness occurs in this portion, there is no practical problem.

(Effect of the Invention) As described above, the method of cleaning and drying an article using water according to the present invention uses the water that does not destroy the global environment to clean an integrated circuit or the like. In addition, it can dry well and plays a large role in protecting the global environment.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) H01L 21/304 F26B 21/00 B08B 3/00-3/14

Claims (1)

(57) [Claims] 1. A method for washing and drying an article using water, comprising the first to third steps shown in the following (a) to (c). (A) After storing an object to be cleaned in a sealable cleaning container,
Water vapor sufficiently higher than the surface temperature of the object to be cleaned is fed into the cleaning container, and the water vapor is condensed on the surface of the object to be cleaned, thereby humidifying and cleaning the surface of the object to be cleaned. The first step to be performed. (B) After the first step, a second step of thinning a water film on the surface of the object to be cleaned by blowing a high-temperature, high-humidity gas onto the surface of the object to be cleaned wet with condensed water. (C) After the second step, a third step of reducing the pressure in the cleaning vessel to evaporate a thin water film adhered to the surface of the object to be cleaned.