JPH0737851A - Cleaning device - Google Patents

Abstract

PURPOSE:To contrive to increase the reproducibility and uniformity of the mixed compositional ratio of the mixed treating liquid of a hydrofluoric acid and pure water. CONSTITUTION:A cleaning device has a treating tank 1, which involves semiconductor wafers 3 to be cleaned and in which a treating liquid obtainable by diluting a hydrofluoric acid with pure water is put, a circulating system 21 having a circulating pump 7 for circulating the treating liquid so that the pure water and the hydrofluoric acid, which are sent in this tank 1, are evenly mixed with each other, a filter 8 and the like, a fluorine ion densitometer 10, which measures the concentration of the circulating treating liquid and senses variations of the concentration, and a flow rate controller 11, which controls the flow rates of the pure water and the hydrofluoric acid for sending a prescribed amount of the pure water and the hydrofluoric acid in the tank 1 on the basis of the measurement of this densitometer 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for cleaning semiconductor wafers used in the manufacture of semiconductor devices, and more particularly to an apparatus for cleaning semiconductor wafers with hydrofluoric acid in the manufacturing process.

[0002]

2. Description of the Related Art In the manufacture of semiconductor devices, it is necessary to keep the surface of a semiconductor wafer clean. This is because, for example, contamination such as foreign matter adhering to the surface of the semiconductor wafer during photo-etching may cause a wiring short circuit or disconnection, and the foreign matter containing a metal may remain attached to the surface of the semiconductor wafer. This is because if the semiconductor wafer is heated, that portion may be alloyed and the pn junction may be short-circuited.

In order to prevent these, cleaning such as pre-cleaning before oxide film formation and post-cleaning after photo-etching is necessary. Conventionally, as shown in FIG. 2, a wafer on which a semiconductor wafer 3 is mounted is mounted. The carrier 2 is immersed in the treatment tank 1, and hydrofluoric acid is supplied from the chemical tank 4 to the treatment tank 1 by the supply pump 5 by opening the valve 16, while pure water 6 is supplied to the treatment tank 1 by opening the valve 17. Then, the hydrofluoric acid and pure water are circulated by a pump 7
The semiconductor wafer 3 was washed while being circulated by, filtered by the filter 8 and uniformly mixed. In addition, 12 and 14 are valves for circulation, and 13 and 15 are valves for waste liquid.

[0004]

However, in the above-mentioned conventional cleaning apparatus, an error of at least 2% occurs in the reproducibility of the mixed composition ratio of hydrofluoric acid and pure water, and
The uniformity was also relatively low. Therefore, there is a problem in that it is difficult to achieve a desired etching rate when etching a semiconductor wafer with the mixed treatment liquid.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a cleaning device which has high reproducibility and uniformity of the mixing composition ratio of a mixed treatment liquid of hydrofluoric acid and pure water and can realize a desired etching amount. To do.

[0006]

In order to solve the above-mentioned problems, a cleaning apparatus of the present invention includes a processing tank containing a semiconductor wafer to be cleaned and containing a processing solution obtained by diluting hydrofluoric acid with pure water. In order to uniformly mix pure water and hydrofluoric acid fed into the treatment tank, a circulation system having, for example, a circulation pump and a filter for circulating the treatment liquid, and a concentration of the treatment liquid in circulation are measured. Further, the flow rate of the pure water and the hydrofluoric acid is measured in order to feed a predetermined amount of pure water and hydrofluoric acid into the processing tank based on the measurement of the fluorine ion concentration meter and the fluorine ion concentration meter that senses the fluctuation. And a flow rate controller for controlling.

[0007]

In the present invention, the flow rate controller controls the flow rates of pure water and hydrofluoric acid, while supplying pure water and hydrofluoric acid into the processing bath and immersing the semiconductor wafer to be cleaned in the processing solution. Dust adhering to the semiconductor wafer is removed by the treatment liquid, and unnecessary silicon dioxide film or the like is removed by etching.

First, for example, by a circulation pump, the treatment liquid is circulated so that the pure water and hydrofluoric acid fed into the treatment tank are uniformly mixed, and a fluoride ion concentration meter for electrically sensing fluoride ions is provided. Thus, the concentration of the processing liquid in the circulation is measured, and after the fluctuation of the concentration becomes constant and becomes constant, the flow rate controller adjusts to a predetermined fluorine ion concentration. For example, when the concentration of fluorine ions is lower than a predetermined value, a correction amount of hydrofluoric acid is supplied to the processing tank by opening the related pump on the way by the flow rate controller, and the like. If the concentration is higher than the fluorine ion concentration, a correction amount of pure water is supplied to the processing tank.

After that, the semiconductor wafer is put into the processing tank by a carrier or the like, the adjusted processing liquid is circulated again, and the cleaning is performed while filtering the processing liquid with a filter, for example.

[0010]

EXAMPLE An example of the cleaning apparatus according to the present invention will be described below with reference to FIG. FIG. 1 is a block diagram showing the system configuration of the cleaning apparatus in the embodiment.

The cleaning apparatus of this embodiment comprises a treatment tank 1, a valve 12, a concentration monitoring box 9 in which a fluorine ion concentration meter 10 is installed, a circulation pump 7, a filter 8,
A valve 14 is provided in such a state that they are connected to each other in this order, and a circulation system 21 in which the cleaning treatment liquid circulates,
Valve 1 that controls the release and shutoff of pure water by opening and closing operation
7, a chemical tank 4 in which hydrofluoric acid is stored, and a valve 16 for controlling release and shutoff of hydrofluoric acid by opening and closing operations.
And a supply pump 5 that is directly connected to the chemical tank 4 and sends hydrofluoric acid from the chemical tank 4 to the valve 16, and a flow rate controller 11 that controls the supply amount of hydrofluoric acid and pure water to the circulation system 21. A waste liquid valve 13 located in the middle of a path connecting the intermediate portion between the circulation pump 7 and the concentration monitoring box 9 and the processing tank 1,
The waste liquid valve 15 is provided beside the circulation system 21. The processing tank 1 includes an inner tank 1a and an outer tank 1b,
Cleaning is carried out by injecting the processing liquid into the inner tank 1a and immersing the carrier 2 loaded with the semiconductor wafer 3 in the processing liquid, while the outer tank 1b is provided so as to include the inner tank 1a. Inside, the processing liquid overflowing from the inner tank 1a is received, and the processing liquid is caused to flow into the circulation system 21.

In order to generate the processing liquid, the flow rate controller 1
1, the valve 17 is opened, a predetermined amount of pure water 6 is supplied to the processing tank 1, and then the flow controller 11 is used to open the valve 16.
And a predetermined amount of hydrofluoric acid (HF) is supplied from the chemical tank 4 to the processing tank 1 by the supply pump 5. Then, while the waste liquid valve 13 is closed, the valves 12 and 14 are closed.
And the circulation pump 7 is operated to circulate the treatment liquid in the circulation system 21 to make the mixing of hydrofluoric acid and pure water uniform.

Then, a fluoride ion concentration meter 10 which electrically senses the fluoride ions and displays the concentration by voltage.
Thus, the concentration of hydrofluoric acid in the circulating treatment liquid is measured, and when the output value from the fluorine ion concentration meter 10 becomes constant, the mixing condition of the treatment liquid is considered to be completely uniform, and the circulation is stopped.

After that, the flow rate controller 11 adjusts the concentration of the fluorine ions to a predetermined value. This is for example
When the concentration of the fluorine ion is less than the predetermined value, a correction amount of hydrofluoric acid is supplied from the chemical tank 4 to the processing tank 1 by opening the valve 16 by the flow controller 11, and when the concentration of the fluorine ion is more than the predetermined value. Is performed by opening the valve 17 and supplying a correction amount of pure water 6 to the processing tank 1.

After that, the semiconductor wafer 3 mounted on the carrier 2 is put into the inner tank 1a, and cleaning is performed while circulating the processing solution whose concentration has been adjusted again in the circulation system 21. At this time, the filter 8 is used. The treatment liquid in circulation is filtered.

After the cleaning of the semiconductor wafer 3 is completed in this way, the valves 12 and 14 are closed and the waste liquid valves 13 and 15 are opened to discard the processing liquid.

[0017]

As described above, in the cleaning apparatus according to the present invention, the concentration of hydrofluoric acid and its fluctuation are accurately read by the fluorine ion concentration meter which measures the concentration of hydrofluoric acid while circulating the treatment liquid. By controlling the ion concentration so as to keep it at a predetermined value, the reproducibility and uniformity of the mixed composition ratio of the mixed treatment liquid of hydrofluoric acid and pure water are increased,
As a result, it is possible to realize a cleaning device with less variation in etching amount.

[Brief description of drawings]

FIG. 1 is a block diagram showing a system configuration of a cleaning apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a system configuration of a conventional cleaning device.

[Explanation of symbols]

 1 Processing Tank 3 Semiconductor Wafer 4 Chemical Tank 5 Supply Pump 6 Pure Water 7 Circulation Pump 8 Filter 10 Fluorine Ion Concentration Meter 11 Flow Controllers 12 and 14 Processing Liquid Circulation Valve 16 Hydrofluoric Acid Supply Valve 17 Pure Water Supply Valve

Claims (1)

[Claims] 1. A cleaning apparatus for cleaning a semiconductor wafer with a processing solution obtained by diluting hydrofluoric acid with pure water, the processing tank containing a semiconductor wafer to be cleaned, and a processing tank in which the processing solution is placed, and the processing tank is fed into the processing tank. A circulation system for circulating the treatment liquid, a fluorine ion concentration meter for measuring the fluorine ion concentration of the treatment liquid circulating in the circulation system, and feeding into the treatment tank according to the measurement of the fluorine ion concentration meter And a flow rate controller for controlling the flow rates of the pure water and hydrofluoric acid.