JP2000232088A - Method for cleaning and drying semiconductor wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize suppression of undried part defects of a semiconductor wafer and to reduce the amount of chemicals used. SOLUTION: This method comprises a step of supplying warm pure water in a water rinsing bath 3 from its bottom for cleaning semiconductor wafers, a step of lifting up the semiconductor wafers from the bath 3 in an up-flow state under an atmosphere of alcoholic steam by gas supplied from a movable nozzle 18, and a step of drying the semiconductor wafers under reduced pressure by spraying an inert gas from the nozzle 18.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaning and drying a semiconductor wafer to obtain a clean surface by removing particles, metal contamination and organic contamination on the surface of the semiconductor wafer.

[0002]

2. Description of the Related Art With the high integration of semiconductor devices, each contamination such as particles and chemical contaminants on a wafer surface has a great influence on product yield and reliability. Its importance is increasing.

As a method for satisfying these requirements, a cleaning and drying apparatus employs a reduced-pressure drying method in a one-bath cleaning apparatus. As a cleaning method, the chemical is disposable,
Each of the above contaminations is reduced, and a highly clean wafer surface can be realized.

FIG. 3 is a system configuration diagram of a one-bath cleaning / vacuum drying processing chamber related to a conventional semiconductor wafer cleaning / drying method. The lid 1 is opened, and the wafer is put into the washing tank 3 by the transfer robot 2. In the washing tank 3, cold pure water is injected from a pure water supply line 5. Thereafter, a water rinsing process is performed for a certain period of time to remove wafer residues.

On the other hand, at the same time as performing the water washing process,
IPA (isopropyl alcohol) supply line 7 to I
IPA is sprayed from the PA / N2 nozzle 8 and the washing tank 3
An IPA layer is formed at the interface of the substrate.

As a result, when the transfer robot 2 moves upward, the wafer passes through the IPA layer on the pure water surface of the washing tank 3, and at the same time, the water on the wafer surface is replaced with the IPA by the Marangoni effect. At this time, the cold pure water in the washing tank 3 is drained by opening a valve to the drain line 6.

Next, the wafer whose surface has been replaced with IPA is made into a nitrogen atmosphere in the chamber by N 2 gas from an N 2 supply line 9 sprayed by an IPA / N 2 nozzle 8. In this state, the pressure is reduced from the pressure reducing pump line 10,
Drying of the wafer is achieved without contact with air.

[0008] However, the above-mentioned washing and drying method has several problems to be solved. First, when the surface of the wafer is replaced with IPA from moisture by the Marangoni effect, depending on the surface condition of the wafer itself, it cannot be efficiently replaced if the surface is hydrophobic. For this reason, there is a concern about residual drying. Secondly, as described in the former, if the wafer has a hydrophobic surface, the amount of IPA spray increases, which is a serious problem in the future in consideration of environmental aspects.

[0009]

SUMMARY OF THE INVENTION As a washing and drying method,
The one-bath washing / vacuum drying processing chamber system, which achieves space saving, low cost, and high throughput with relatively high performance, also has a concern that residual drying, chemical solution usage, and waste liquid increase. In the future, achieving both high cleanliness and environmentally friendly running costs will be important issues.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above circumstances, and an object thereof is to provide a method of cleaning and drying a semiconductor wafer which can suppress the remaining residue of the semiconductor wafer from drying and reduce the amount of IPA used. To provide.

[0011]

SUMMARY OF THE INVENTION A method for cleaning and drying a semiconductor wafer according to the present invention comprises the steps of: supplying hot pure water from a bottom of the cleaning tank to a cleaning tank to clean the semiconductor wafer; A step of lifting the semiconductor wafer from a washing tank in an upflow state of the hot pure water under a steam atmosphere for reducing the surface tension of the pure water, and drying the semiconductor wafer under reduced pressure by spraying an inert gas from the movable nozzle. And a step.

According to the present invention, the Marangoni effect is improved by improving the hydrophobic surface of the wafer state (formation of a natural oxide film) by the hot pure water treatment. Further, the efficiency of spraying the alcohol vapor or the inert gas onto the semiconductor wafer by the movable nozzle is improved, and the usage amount is reduced.

[0013]

FIG. 1 is a system configuration diagram of a one-bath cleaning and reduced-pressure drying processing chamber according to a method of cleaning and drying a semiconductor wafer according to an embodiment of the present invention. FIG. 2 is a semiconductor wafer to which the system of FIG. 1 is applied. FIG. 3 is a process flow chart showing a washing and drying method in the order of steps.

The cover (cover) 1 is opened, and the wafer is loaded into the washing tank 3 by the transfer robot 2. In the washing tank 3,
Hot pure water is supplied from the bottom. The hot pure water is provided with a pure water supply line 5 and a hot pure water supply line 11,
Each supply valve 12 supplies a suitable constant amount of warm pure water (for example, about 60 ° C.).

Thereafter, the semiconductor wafer is subjected to a water rinsing process for a certain period of time to remove residues on the wafer. During the rinsing process, the wafer may be slightly vibrated in the rinsing tank 3 by ultrasonic waves or the like, or may be slowly shaken.

On the other hand, at the same time as performing the water washing process,
IPA is sprayed from a movable IPA / N2 nozzle 18 from an IPA (isopropyl alcohol) supply line 7,
An IPA layer is formed on the interface of the washing tank 3. The formation of the IPA layer is for replacing the water on the wafer surface with IPA by utilizing the Marangoni effect when the wafer passes through the interface of the washing tank 3.

The hot pure water cleaning process according to the present invention makes it easy to form a natural oxide film by performing the hot water process on a portion that is a hydrophobic surface depending on the state of a wafer to be processed.
Thereby, the Marangoni effect when the wafer passes through the interface of the washing tank can be further enhanced.

In order to end the rinsing process, the transfer robot 2 is raised, and the wafer is pulled up at a low speed. in the meantime,
The hot pure water is slowly overflowing into the spare tank 31 of the washing tank 3. This suppresses particles and the like floating on the water surface due to the water washing process from re-adhering to the wafer and the like.

Thus, the movable IPA / N2 nozzle 1
The wafer is pulled up at a low speed from the washing tank 3 in the up-flow state under the nitrogen / IPA atmosphere of FIG. The Marangoni effect makes the gas-liquid interface on the wafer surface uniform,
At the gas-liquid interface, replacement with water by the condensation of IPA vapor is performed smoothly. Condensation of the IPA vapor also occurs on the wafer surface, and an IPA layer is formed.

By the movable IPA / N 2 nozzle 18 employed in the present invention, the conventionally fixed spraying can be efficiently achieved on the wafer surface, so that the remaining dry defects can be suppressed and the amount of IPA used can be greatly reduced. .

Next, the pure water in the washing tank 3 is drained through the drain line 6 by opening the valve 4. Surface is I
The wafer replaced with PA enters a drying process while the inside of the chamber is changed to a nitrogen atmosphere by the N2 gas from the N2 supply line 9 sprayed by the movable IPA / N2 nozzle 18. The pressure is reduced from the vacuum pump line 10 and drying of the wafer is achieved without contacting air. Thereafter, the wafer is taken out of the chamber by the transfer robot.

According to the above embodiment, the following advantages can be obtained. First, by performing the rinsing process with warm pure water, it is possible to efficiently use the Marangoni effect. As a result, it is possible to suppress a defect due to dry residue, which is concerned with a dense pattern. Secondly, when the wafer is lifted after the rinsing process, the upflow is performed, so that particle transfer with an adjacent wafer can be suppressed. Third, since the IPA / N2 nozzle 18 is variable during lifting of the wafer after the water washing process and drying under reduced pressure,
IPA or N2 gas is efficiently sprayed onto the wafer, and the amount of IPA used can be reduced.

In the present invention, IPA (isopropyl alcohol) is used as the organic solvent for lowering the surface tension of pure water with respect to the wafer. However, ethyl alcohol or methyl alcohol may be used. In addition, ketones and ethers are also conceivable, but it can be said that IPA, which has a relatively low impurity content and is widely provided in the market, is preferable. Further, N2 gas is used as the inert gas, but it is not limited to this.

[0024]

As described above, according to the present invention,
The Marangoni effect is improved by improving the hydrophobic surface of the wafer state by hot pure water treatment, and the efficiency of spraying alcohol vapor or inert gas to the semiconductor wafer by the movable nozzle is improved. In this system, it is possible to provide a method for cleaning and drying a semiconductor wafer with high cleanliness and low running cost, which contributes to a reduction in residual defects and a reduction in the amount of chemical solution used.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of a one-bath cleaning / vacuum drying processing chamber according to a semiconductor wafer cleaning / drying method according to an embodiment of the present invention.

FIG. 2 is a process flowchart showing a method of cleaning and drying a semiconductor wafer to which the system of FIG. 1 is applied in the order of steps;

FIG. 3 is a system configuration diagram of a one-bath cleaning / vacuum drying processing chamber related to a conventional semiconductor wafer cleaning / drying method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Lid (cover), 2 ... Transport robot, 3 ... Wash tank, 4
... drain valve, 5 ... pure water supply line, 6 ... drain line,
7 ... IPA supply line, 9 ... N2 gas supply line, 10
... decompression exhaust line, 11 ... hot pure water supply line, 12 ... supply valve, 18 ... movable IPA / N2 nozzle, 31 ... preliminary tank

Claims (2)

[Claims] A step of supplying hot pure water from the bottom into a washing tank to clean the semiconductor wafer; and a step of reducing the surface tension of the pure water on the wafer by a gas supplied from a movable nozzle under a steam atmosphere to reduce the surface tension of the pure water. Cleaning and drying the semiconductor wafer, comprising: a step of lifting the semiconductor wafer from a washing tank in an upflow state; and a step of drying the semiconductor wafer under reduced pressure by spraying an inert gas from the movable nozzle. Method. 2. A step of supplying hot pure water into a washing tank from the bottom thereof to wash the semiconductor wafer, and a step of supplying nitrogen / gas by a supply gas from a movable IPA / N2 nozzle.
A step of pulling up the semiconductor wafer at a low speed from a washing tank in an upflow state of the hot pure water in an IPA vapor atmosphere; and drying the semiconductor wafer under reduced pressure while purging nitrogen with a supply gas from the movable IPA / N2 nozzle. And a method for cleaning and drying a semiconductor wafer.