KR20110129583A - Surface treatment method of silicon wafer - Google Patents

Abstract

PURPOSE: A silicon wafer surface processing method is provided to arrange uniform hydroxyl group on the surface of a wafer, thereby making a thin film layer with a uniform thickness during a thin film formation process by atomic layer deposition. CONSTITUTION: An RCA(Radio Corporation of America) washing process is performed(S10). The RCA washed surface of a silicon wafer is washed with hydrofluoric acid which is an aqueous solution of hydrogen fluoride(S20). The washed silicon wafer is carried to the inside of an ALD(Atomic Layer Deposition) chamber(S30). The surface of the silicon wafer is processed by injecting an ozone gas within the ALD chamber where the silicon wafer is embedded(S40). A silicon wafer washing process by the hydrofluoric acid is performed in a predetermined space communicated with the ALD chamber. A drying process is performed when transferring the wafer.

Description

SURFACE TREATMENT METHOD OF SILICON WAFER

The present invention relates to a method of chemically treating a silicon wafer surface to deposit a thin film of uniform thickness on a silicon wafer.

In the semiconductor wafer manufacturing process, atomic layer deposition is used, which forms a thin film having a very fine thickness as an atomic layer on the surface of a pure silicon semiconductor wafer. Contamination of the wafer surface before thin film deposition causes a decrease in the yield of semiconductor devices after thin film deposition and a decrease in dielectric constant. Therefore, it is necessary to reduce the roughness of the thin film surface through the surface treatment of the silicon wafer before thin film deposition so that a thin film layer having a uniform thickness can be obtained in the future. For this purpose, a uniform hydroxyl group is finally formed on the surface of the pure silicon wafer by a chemical method so that a uniform thickness thin film layer can be obtained through atomic layer deposition.

Korean Patent No. 914606 discloses a method for forming a wet gate oxide. After RCA chemical treatment, the semiconductor wafer is reprocessed with a hydrofluoric acid solution and ozone water is again supplied to the wafer surface. In this case, after all the surface treatment of the wafer is finished, it must be re-purchased in the equipment for thin film deposition, so that the possibility of adhesion of impurities such as fine particles on the wafer surface increases during the wafer transfer process.

In addition, Korean Patent Registration No. 841995 discloses a single wafer cleaning apparatus and a cleaning method. This uses a separate device for cleaning the wafer. After embedding the wafer inside the device, ozone gas is injected, and the cleaning liquid is sprayed to perform surface cleaning. This prior art also has to transfer the wafer to the deposition equipment for thin film deposition after the surface cleaning of the wafer is completed. Therefore, during the transfer process, the surface of the already cleaned wafer is likely to be contaminated by fine particles or the like.

It is an object of the present invention to provide a method for surface treatment of a silicon wafer that enables to minimize contamination of the wafer surface prior to thin film deposition.

In order to solve the above problems, the silicon wafer surface treatment method of the present invention is a silicon wafer surface cleaning method, performing RCA cleaning, cleaning the RCA cleaned silicon wafer surface with hydrofluoric acid (HF), the Moving the silicon wafer cleaned with hydrofluoric acid into the ADL chamber, and treating the surface of the silicon wafer by injecting ozone gas into the ALD chamber in which the silicon wafer is embedded.

The cleaning of the silicon wafer with the hydrofluoric acid may be performed in a predetermined space in communication with the ALD chamber.

It is possible to have an apparatus for transferring the silicon wafer cleaned in the hydrofluoric acid into the ALD chamber.

Drying may be performed when the wafer is transferred, and the drying may be performed by air spray (air shower). In addition, the drying may be made of an infrared lamp.

According to the method for treating the surface of the silicon wafer of the present invention configured as described above, a uniform hydroxyl group is formed on the surface of the wafer while minimizing the contamination of the wafer surface that may occur before the thin film deposition, and thus the thin film by atomic layer deposition. When forming, it is possible to obtain a thin film layer of uniform thickness.

1 is a flowchart of a surface treatment method of a silicon wafer of the present invention.

Hereinafter, a method of surface treatment of a silicon wafer according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the present specification, the same or similar reference numerals are assigned to the same or similar configurations in different embodiments, and the description thereof is replaced with the first description.

In general, the technology for cleaning the semiconductor wafer surface is largely divided into wet cleaning and dry cleaning. The cleaning process is a process of removing impurities present on the wafer surface. RCA wet cleaning of silicon wafers (the cleaning method of Radio Corporation of America) is the longest used wafer cleaning method and is the most common method used for wet chemical cleaning.

1 is a flowchart illustrating a process of performing a surface treatment method of a silicon wafer according to a preferred embodiment of the present invention.

Referring to FIG. 1, the entire process of the surface treatment method of the silicon wafer of the present invention comprises the step of performing a RCA cleaning of a silicon wafer (S10), and a RCA cleaned silicon wafer to hydrofluoric acid (HF). The step (S20) of processing, the step of moving the wafer treated with hydrofluoric acid into the chamber for ALD (ATOMIC LAYER DEPOSITION) (S30), the step of injecting ozone gas into the ALD chamber (S40).

RCA cleaning step (S10) is a wet process following the general RCA cleaning method, the solution used for RCA cleaning is composed of high-purity deionized water, hydrogen peroxide (H2O2), ammonium hydroxide (NH4OH), hydrochloric acid (HCl), etc. . These usually consist of two stages: RCA standard clean-1 (SC-1) and standard clean-2 (SC-2).

In standard cleaning step 1, surface organic materials are oxidized and dissolved due to strong oxidation, and residual metal impurities (Au, Ag, Cu, Ni, Cd, Zn, Co, Cr, etc.) are also removed.

In standard washing step 2, Al (OH) 3, Fe (OH) 3, Mg (OH) 2, Zn (OH) 2 and alkaline hydroxides (Al3 +, Fe3 +, Mg2 +) and hydroxides insoluble in NH4OH Remaining substances that are not removed are removed.

Through the RCA cleaning step S10, some of the metal impurities such as copper, calcium, and zinc existing on the wafer surface may be removed. However, even after the RCA cleaning step (S10), further cleaning is necessary because metal impurities may remain on the wafer surface or may be reattached after the cleaning.

The step S20 of treating the RCA cleaned silicon wafer with hydrofluoric acid (HF) is performed to remove metal impurities that remain or reattach to the wafer surface even after undergoing RCA cleaning.

Metal impurities remaining on the wafer surface may cause uneven thickness of the thin film layer after the deposition of the barrier, so it is necessary to remove them as cleanly as possible. To this end, it is preferable to immerse the RCA-cleaned wafer in a container containing a dilute hydrofluoric acid solution for a predetermined time to clean the surface once again.

Cleaning with hydrofluoric acid (S20) may be performed in a predetermined space provided separately in the atomic layer thin film deposition equipment, that is, ALD equipment. In addition, the predetermined space provided separately may be in communication with the ALD chamber in which thin film deposition is directly performed.

After the step S20 of cleaning with hydrofluoric acid is completed, the wafer is moved into the ALD chamber, that is, the SLD.

Since hydrofluoric acid remaining on the surface of the wafer subjected to the step of cleaning with hydrofluoric acid (S20) may shorten the life of the ALD chamber or cause contamination of the wafer during thin film deposition, it is preferable to dry and remove the hydrofluoric acid.

The drying is preferably performed while the wafer is moved (S30) into the ALD chamber in a separate space in which the step of cleaning with hydrofluoric acid (S20) is performed. In this case, the drying may be performed through an air shower device while the wafer is moved into the ALD chamber (S30). In addition, drying may be performed by an infrared lamp while the wafer is moved into the ALD chamber (S30).

When the wafer passed through the hydrofluoric acid cleaning step (S20) is transferred to the ALD chamber (S30), the wafer may be made by a predetermined unit installed in the ALD equipment.

H atoms remain on the wafer surface after the step of cleaning with hydrofluoric acid (S20). That is, the wafer after H-terminated by hydrofluoric acid does not react well with molecules such as metal organic compounds, which are ALD precursors, due to H atoms present on the surface. Then, during the ALD process, a film grows in a part, and the surface of the wafer becomes uneven and rough after thin film deposition.

The step of injecting ozone gas into the chamber (S40) is performed to convert the H atomic layer present on the wafer surface into the OH layer using ozone gas after the step S30 of transferring the wafer into the ALD chamber is completed. This is to improve the reaction with metal organic compounds, which are precursors used in ALD thin film deposition.

When the ALD precursor reacts well with the surface of the silicon wafer during thin film deposition of the silicon wafer, the thickness of the deposited thin film layer may be uniform, and thus the surface of the wafer may be smoothly formed after the deposition.

The ozone gas used at this time can be injected and discharged to create a certain time atmosphere in the ALD chamber. It is possible to use a vacuum pump or the like to discharge the ozone gas.

In the space where the step of cleaning with hydrofluoric acid (S20) is performed and the ALD chamber into which ozone gas is injected, partitions are formed in each space, and the inner space may be separated.

The surface treatment method of the silicon wafer as described above is not limited to the configuration and operation of the embodiments described above. The above embodiments may be configured such that various modifications may be made by selectively combining all or part of the embodiments.

Claims (6)

In the silicon wafer surface cleaning method,
Performing an RCA clean;
Cleaning the RCA cleaned silicon wafer surface with hydrofluoric acid (HF);
Moving the cleaned silicon wafer into an ADL chamber; And
And treating the surface of the silicon wafer by injecting ozone gas into the ALD chamber in which the silicon wafer is embedded.
The method of claim 1,
Cleaning the silicon wafer with the hydrofluoric acid (HF) comprises a predetermined space in communication with the ALD chamber.
The method of claim 1,
And a unit for transferring the silicon wafer cleaned in the hydrofluoric acid (HF) into the ALD chamber.
The method of claim 3, wherein
Drying is carried out when the said wafer is conveyed, The surface treatment method of the silicon wafer.
The method of claim 4, wherein
And the drying comprises air spraying (air shower).
The method of claim 4, wherein
Wherein said drying comprises an infrared lamp.

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