JPH05166776A - Method and apparatus for cleaning semiconductor wafer - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a semiconductor wafer cleaning method and an apparatus thereof, in which a constant amount of active oxygen is always maintained, cleaning power is uniform, and maintenance is easy. The above-mentioned objects are achieved by a semiconductor wafer cleaning method and apparatus, in which cleaning is performed while introducing ozone into a cleaning liquid composed of hydrochloric acid and pure water or ammonia water and pure water.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor wafer cleaning method and apparatus.

[0002]

2. Description of the Related Art In a semiconductor device manufacturing process, cleaning of a wafer substrate at the time of inputting, pre-cleaning of a thermal oxidation process, pre-cleaning of a CVD process, or cleaning of a semiconductor wafer for removing phosphorus glass has been conventionally performed by (1). NH ₄ OH + H ₂ O ₂
+ H ₂ O mixed solution immersion treatment (1: 1: 5, 80 ° C, 10
Min), (2) pure water rinse, (3) HF + H ₂ O immersion treatment (containing 1% HF), (4) pure water rinse, (5) HCl +
Immersion treatment of H ₂ O ₂ + H ₂ O mixture (1: 1: 6, 80
So-called RCA cleaning method (W. Kern et.al .: RCA R), in which (6) pure water rinsing and (7) drying are successively performed
eveiw, 31 , p.187, 1970), based on the mixing ratio of each processing solution, the immersion time, the heating temperature, and (1) above.
In general, a cleaning method that is appropriately selected and used according to the process, such as changing the order of the cleaning treatments with the cleaning liquids of (2) and (3), is used.

Here, (1) NH ₄ OH + H ₂ O ₂ + H
_{The 2} O mixed solution is effective in removing foreign substances such as organic substances and heavy metals, and (3) HF + H ₂ O is effective in removing foreign substances adhering to the substrate surface at the same time as removing the oxide film. ) HCl + H ₂ O ₂ + H ₂ O mixture is said to be effective in removing heavy metals.

Among the above-mentioned cleaning solutions, (1) NH ₄ OH + H ₂ O ₂ + H ₂ O mixed solution, which is an alkaline cleaning solution, and (5) HCl + H ₂ O ₂ + H ₂ O mixed solution, which is an acid-based cleaning solution, contain hydrogen peroxide. It contains water (H ₂ O ₂ ), and this hydrogen peroxide solution is decomposed in the solution and the released active oxygen enhances the detergency, and is particularly effective in removing metal contamination. ing.

[0005]

However, the cleaning liquid containing the above-mentioned hydrogen peroxide solution has a concentration of active oxygen gradually decreased as the hydrogen peroxide in the solution is decomposed, and its cleaning power is weakened. Become. In particular, the cleaning effect when the cleaning liquid is heated is abruptly weakened. For this reason, the cleaning solution must be maintained and managed so that there is no difference in the effect of the cleaning solution at the beginning and end of cleaning, but if hydrogen peroxide solution is added during cleaning, the temperature will drop and the cleaning time will change. There are problems such as uneven strength.

Therefore, an object of the present invention is to provide a method for cleaning a semiconductor wafer and an apparatus therefor, in which a constant amount of active oxygen is always maintained, the cleaning power is uniform, and the maintenance is easy.

[0007]

The above objects can be achieved by a method for cleaning a semiconductor wafer, which comprises cleaning while introducing ozone into a cleaning liquid composed of hydrochloric acid and pure water.

The above objects are achieved by a method for cleaning a semiconductor wafer, which is characterized in that cleaning is performed while introducing ozone into a cleaning liquid composed of ammonia water and pure water.

Further, the above objects are achieved by a cleaning device for cleaning a semiconductor wafer while introducing ozone into a cleaning liquid composed of hydrochloric acid and pure water.

Further, the above objects are achieved by a cleaning apparatus for cleaning a semiconductor wafer while introducing ozone into a cleaning liquid composed of ammonia water and pure water.

[0011]

According to the present invention, as described above, ozone is introduced into an acid-based cleaning solution composed of hydrochloric acid and pure water, or an alkaline-based cleaning solution composed of ammonia water and pure water, and the amount of ozone introduced is controlled. Since the active oxygen concentration in the cleaning liquid is constantly kept constant, the cleaning effect does not change with time, and good cleaning power can be maintained.

Further, by continuously supplying active oxygen to the wafer surface, an oxide film is continuously grown on the wafer surface without change over time, as compared with the case where hydrogen peroxide solution is used as a conventional acid-based or alkaline-based cleaning liquid. Also, if an oxide film grows to about 5 to 10 angstroms, NH ₄ OH or H
The oxide film can be etched by Cl, and a clean wafer surface can be maintained constantly.

[0013]

The present invention will be described in detail below with reference to examples. FIG. 1 is a drawing showing an embodiment of the cleaning apparatus of the present invention.

Example 1 First, hydrochloric acid (HCl) and ultrapure water (H ₂ O) were used as the cleaning liquid 9 in the cleaning tank 1 in a weight ratio of HCl: H ₂ O =
It is supplied at a ratio of 0.5 to 1: 5 by using a weighing supply device, for example, a weighing pump, a weighing tank, a liquid level sensor and the like. Next, while metering the ozone (O ₃ ) gas 8 with the flow meter 7, the supply rate of 0.5 to 10 liters / min was applied to the cleaning tank 1 through the filter 6 and the conduit 5 to uniformly flow in the cleaning liquid by the bubbler 3. To be introduced. After ozone is sufficiently and uniformly mixed in the cleaning liquid, the wafer of the semiconductor device is set on a wafer carrier or the like used for normal cleaning and immersed in the cleaning tank 1. At this time, the cleaning liquid may be heated by the heater 2 in order to improve the cleaning effect, and the temperature thereof is from room temperature to about 90 ° C. Further, in order to introduce ozone gas into the cleaning liquid, a stirrer is provided in the cleaning tank without using a bubbler as described above, ozone gas is introduced through a conduit, and the ozone is evenly mixed by the stirrer. Good.

The time for immersing the wafer in the cleaning liquid may be the time usually carried out in such cleaning, and is not particularly limited, but is, for example, about 5 to 10 minutes.

After the completion of cleaning, the wafer is taken out, rinsed with water, dried, or if necessary, diluted hydrofluoric acid cleaning is performed.
After washing with water and drying, the washing process is completed.

Example 2 A wafer can be cleaned in the same manner as in Example 1 except that ammonia water (NH ₄ OH) is used as a cleaning liquid instead of hydrochloric acid.

[0018]

As described above, the cleaning method according to the present invention is
Since a fixed amount of active oxygen in the cleaning liquid is constantly supplied by ozone, it is possible to maintain good cleaning power at any time without changing its concentration, and it seems that it is usually used in the manufacturing process of semiconductor wafers. However, when several batches are continuously washed, there is no problem such as a difference in washing effect between the first batch and other batches.

[Brief description of drawings]

FIG. 1 is a schematic view showing a cleaning device according to an embodiment of the present invention.

Claims (4)

[Claims] 1. A method of cleaning a semiconductor wafer, which comprises cleaning while introducing ozone into a cleaning liquid composed of hydrochloric acid and pure water. 2. A method of cleaning a semiconductor wafer, which comprises cleaning while introducing ozone into a cleaning liquid composed of ammonia water and pure water. 3. A semiconductor device which is cleaned while introducing ozone into a cleaning liquid composed of hydrochloric acid and pure water. 4. A semiconductor device which is cleaned while introducing ozone into a cleaning liquid composed of ammonia water and pure water.