KR20100057326A - Apparatus and method for cleaning wafer - Google Patents

Abstract

PURPOSE: A cleaning method of wafer replaces the ionized water rinse process and SC 2(Standard Cleaning 2) solution cleaning process with the gas dissolving water cleaning process. The fabrication costs are reduced and process is simplified. CONSTITUTION: Wafer is washed by using the SC 1(Standard Cleaning 1) solution(S110). The gas is dissolved in the ultra-pure water and the gas dissolving water becomes(S120). Wafer is washed by using the gas dissolving water which becomes as described above(S130). Corpuscle and metal contamination of wafer are at the same time removed.

Description

Wafer cleaning method {APPARATUS AND METHOD FOR CLEANING WAFER}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of cleaning a wafer, and more particularly, to a wafer cleaning method in which the cleaning ability of a wafer is improved using gas dissolved water.

In general, a wafer is manufactured as a wafer for manufacturing a semiconductor device through a series of processes such as a slicing process, a grinding process, a lapping process, an etching process, and a polishing process. At this time, the surface of the wafer is contaminated by various contaminants during the process. Representative contaminants include fine particles, metal contaminants, organic contaminants, etc., such contaminants cause a decrease in the production yield of the semiconductor device.

In general, in the wafer cleaning process for removing such contaminants, SC1 (Standard Cleaning 1) and SC2 (Standard Cleaning 2) solutions are used alone or in combination with various types of cleaning solutions. Here, the SC1 solution is a mixture of ammonia water, hydrogen peroxide and deionized water, mainly used to remove fine particles, and the SC2 solution is a mixture of hydrochloric acid, hydrogen peroxide and ultrapure water, mainly for removing metal contaminants. Used.

1 is a flowchart schematically showing a method of cleaning a wafer according to the prior art. As shown in FIG. 1, according to the prior art, first, the wafer is cleaned using the SC1 solution (S10) and rinsed with ultrapure water (S20). Next, the wafer is cleaned using the SC2 solution (S30), rinsed with ultrapure water (S40), and the wafer is dried (S50). As described above, in the conventional method, since washing is performed by using a chemical solution such as SC1 or SC2, the number of processes increases because the process must be rinsed with ultrapure water.

On the other hand, sulfuric acid is used to remove organic contaminants on the wafer, or ozone may be mixed with water and used as a cleaning liquid. In this regard, Patent Publication No. 1998-0015254 and Patent Publication No. 1999-0079059 disclose a cleaning method in which a wafer is immersed in a solution mixed with ozone and water to remove organic matter attached to the wafer.

However, such a cleaning method using ozone has been used only for the purpose of removing organic matters, and it is expensive because various chemicals are still used to remove fine particles and metal contaminants other than organic matters. In addition, there are problems in that it is difficult to secure safety because many dangerous substances, including strong acid such as hydrochloric acid or sulfuric acid, are used in the cleaning process. In addition, the discharge of wastewater containing chemicals generated in the process to the outside can cause environmental pollution, and therefore can be expensive to treat such wastewater.

The present invention has been made to solve the above problems, it is an object of the present invention to provide a wafer cleaning method that is less expensive and ensures the safety of the process, less polluting the environment in a simplified process.

Wafer cleaning method for achieving the above object, the step of cleaning the wafer using the SC1 solution; And cleaning the wafer using gas dissolved water in which gas is dissolved in ultrapure water.

In addition, another wafer cleaning method for achieving the above object comprises the steps of degassing the gas remaining in the ultrapure water; Dissolving gas in the deaerated ultrapure water to produce gas dissolved water; And cleaning the wafer using the gas dissolved water.

According to the present invention, it is possible to remove particulates and metal contaminants at the same time, with excellent cleaning efficiency beyond the conventional cleaning ability, without using SC2 solution or sulfuric acid, which is conventionally used in the process of cleaning the wafer. In addition, the use of gas dissolved water in addition to chemicals can reduce costs for process or waste water treatment and less contaminate the environment. In addition, process safety can be secured by reducing the use of dangerous substances such as hydrochloric acid or sulfuric acid, and the process can be simplified by replacing the ultrapure rinse process and the SC2 solution cleaning process with a gas dissolved water cleaning process.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the specification and claims should not be construed as having a conventional or dictionary meaning, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention.

Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiments of the present invention and do not represent all of the technical spirit of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

2 is a schematic diagram showing the configuration of an apparatus 10 for cleaning a wafer according to an embodiment of the present invention.

Referring to the drawings, the wafer cleaning apparatus 10 used in the embodiment of the present invention includes a wafer cleaning portion 17 and a gas dissolving portion 13.

The gas dissolving unit 13 dissolves gas in ultrapure water supplied to the wafer cleaning unit 17 to generate gas dissolved water. According to one embodiment of the present invention, the gas to be dissolved may be supplied to the gas contactor through the gas supply pipe 14 to be dissolved in ultrapure water. In this case, the gas contactor may use a membrane contactor or a waterfall contact type gas contactor, but the present invention is not limited thereto. In addition, the gas dissolving unit 13 may increase the pressure of the gas contactor portion, thereby increasing the amount of gas dissolved in the ultrapure water, thereby improving cleaning efficiency. In addition, the gas dissolving unit 13 may include a gas degassing pipe 15, and residual gas not dissolved in ultrapure water may be discharged to the outside through the gas degassing pipe 15.

On the other hand, the gas dissolved in ultrapure water by the gas dissolving unit 13 preferably includes any one selected from the group consisting of hydrogen, nitrogen, oxygen, and ozone or a combination thereof.

The wafer cleaning unit 17 accommodates a cleaning liquid and a wafer to be cleaned. When the wafer is mounted in the wafer cleaner 17, the wafer cleaner 17 cleans the wafer using the cleaning liquid. According to the present invention, the wafer cleaning unit 17 cleans the wafer using the gas dissolved water in which the gas is dissolved by the gas dissolving unit 13 as the cleaning liquid. Meanwhile, the wafer cleaner 17 may be configured as an overflow bath having a simple shape as shown in FIG. 2, but the present invention is not limited thereto.

3 is a configuration diagram schematically showing the configuration of another wafer cleaning apparatus 20 used in the embodiment of the present invention.

Referring to FIG. 3, the wafer cleaning unit 27 may include a circulation bath, and the wafer cleaning unit 27 may include an inner tank in which the cleaning liquid and the wafer are accommodated, and an outer tank for circulating the cleaning liquid overflowed from the inner tank. have. The outer tub is installed outside the upper half of the inner tub and is configured to receive a cleaning liquid that overflows over both walls of the inner tub. The overflowed cleaning liquid may be supplied to the gas dissolving unit 23 by the circulation pump 28 to further dissolve the gas. When a gas concentration of sufficient concentration is secured, the wafer cleaner 27 composed of the overflow bath as shown in FIG. 2 may be used. Otherwise, the wafer cleaner 27 composed of the circulation bath shown in FIG. 3 may be useful. can do.

It is preferable that the wafer cleaning apparatuses 10 and 20 used in the embodiment of the present invention further include degassing portions 12 and 22. The ultrapure water supplied to the gas dissolving parts 13 and 23 may contain unwanted residual gas. In this case, the gas solubility of the ultrapure water is limited so that the amount of gas dissolved by the gas dissolving parts 13 and 23 may be reduced. Can reduce the cleaning efficiency. Therefore, the degassing parts 12 and 22 remove the remaining gas from the ultrapure water before the gas dissolving parts 13 and 23 dissolve the gas into the ultrapure water, so that the gas can be sufficiently dissolved in the ultrapure water. Meanwhile, the degassers 12 and 22 may have a membrane structure through which liquid passes and gas is removed, and the vacuum pumps 11 and 21 may be provided to remove the gas by the vacuum pumps 11 and 21. Can be.

In addition, the wafer cleaning apparatuses 10 and 20 include an SC1 solution supply part (not shown). The SC1 solution supply section supplies the SC1 solution to the wafer cleaner, where the wafer cleaners 17 and 27 are supplied prior to cleaning the wafer using the gas dissolved water generated by the gas dissolving sections 13 and 23. The wafer is cleaned using the SC1 solution. As described above, the SC1 solution is made by combining ammonia water (NH ₄ OH), hydrogen peroxide (H ₂ O ₂ ), and ultrapure water (H ₂ O), and fine particle removal efficiency is achieved by washing with such SC1 solution. Can improve.

The wafer cleaning apparatuses 10 and 20 may further include an alkaline solution supply unit (not shown). The alkaline solution supply unit adds an alkaline solution to ultrapure water or gas dissolved water in which gas is dissolved. The alkaline solution can enhance the repulsive force between the particles and the wafer to improve the fine particle removal performance of the wafer cleaning apparatus according to the present invention. More preferably, the alkaline solution added by the alkaline solution supply part includes any one selected from the group consisting of NH ₄ OH, KOH, NaOH, TMAH, or a combination thereof.

In addition, the wafer cleaning apparatuses 10 and 20 preferably further include megasonic oscillators 16 and 26. Megasonic oscillators 16 and 26 apply megasonic energy to the surface of the wafer during the cleaning process to increase cleaning efficiency. By applying the megasonic energy in this way, a cavitation effect can be obtained in a low frequency region, and an effect by acoustic streaming in a high frequency region can be obtained.

Next, a cleaning method according to the present invention using the wafer cleaning apparatus having the above configuration will be described. 4 is a flowchart illustrating a flow of a wafer cleaning method according to a preferred embodiment of the present invention.

Referring to FIG. 4, first, a wafer is cleaned using an SC1 solution (S110), and gas is dissolved in ultrapure water to generate gas dissolved water (S120). Then, the wafer is cleaned using the generated gas dissolved water. (S130). Thus, by cleaning the wafer with only the SC1 solution and gas dissolved water, it is possible to effectively remove particulates and metal contaminants on the wafer surface without using the SC2 solution. In addition, since the gas-dissolved water of the present embodiment is not a chemical solution such as SC2 or sulfuric acid, a separate ultrapure water rinsing process is not required. Can be.

On the other hand, as described above, the gas preferably includes any one selected from the group consisting of hydrogen, nitrogen, oxygen, and ozone or a combination thereof.

In the cleaning of the wafer using the gas dissolved water, the wafer may be cleaned using gas dissolved water to which the alkaline solution is added, and then the wafer may be cleaned using gas dissolved water to which the alkaline solution is not added. It can be washed. The alkaline solution may include any one selected from the group consisting of NH ₄ OH, KOH, NaOH, TMAH, or a combination thereof.

In the wafer cleaning method according to the present invention, it is preferable to apply megasonic to the wafer during the cleaning of the wafer. Thus, by applying megasonic, the wafer can be cleaned more efficiently by the cavitation effect and the particle acceleration effect.

In the wafer cleaning method according to the present invention, it is preferable to remove the gas remaining in the ultrapure water before dissolving the gas in the ultrapure water. This is to improve the cleaning efficiency by increasing the concentration of the gas dissolved in ultrapure water as described above.

Hereinafter, the cleaning efficiency of the wafer cleaning method according to the present invention will be described with reference to FIGS. 5 and 6 and Tables 1 and 2. FIG. 5 is a flowchart illustrating a wafer cleaning method according to a comparative example, and FIG. 6 is a flowchart illustrating a wafer cleaning method according to an embodiment of the present invention. In addition, Table 1 and Table 2 show the cleaning results according to Comparative Examples and Examples, and the results of evaluating the concentration of particles and metal contamination on the final wafer surface.

Referring to FIG. 5, in Comparative Example 200, the wafer was cleaned by using a SC1 solution (S210), followed by rinsing using ultrapure water (S220), and drying the wafer (S230). On the other hand, referring to Figure 6, each embodiment 300, after cleaning the wafer using the SC1 solution (S310) after cleaning the wafer using gas dissolved water dissolved in the gas (S320), and dried it ( S330) was performed to clean the wafer. However, Examples 1, 2, and 3 differ in that they differed in the types of gases dissolved in nitrogen, oxygen, and ozone, respectively.

Table 1 shows the relative ratio with respect to the fine particle removal effect of the wafer surface according to a comparative example and an Example. That is, when the fine particle removal effect of the comparative example which does not use gas dissolved water is 100, it shows the relative ratio of each Example with respect to a comparative example. Referring to Table 1, it can be seen that the fine particle removal effect of the wafer surface by cleaning according to each embodiment has a very good effect compared to the comparative example. In particular, in the case of Example 3, the result was good up to 240 compared to the comparative example, the effect was very excellent compared to the comparative example.

Table 2 is a table showing the residual metal contamination concentration of the wafer surface according to the comparative examples and examples, showing the effect of removing metal contamination by each cleaning method, the unit for the numerical value shown in Table 2 is 10 ⁸ atoms / cm ² to be. Referring to Table 2, it can be seen that in the effect of removing metal contaminants, the results are much better when compared to the comparative examples. In particular, according to the embodiment, it can be seen that it has an excellent cleaning ability for alkali metals, such as Na and K, which are removed by conventional SC2 solutions.

As a result, looking at Table 1 and Table 2, it can be said that the wafer cleaning according to the embodiment of the present invention has an excellent effect on the removal of fine particles and the removal of metal contaminants.

Although the present invention has been described above by means of limited embodiments and drawings, the present invention is not limited thereto and will be described below by the person skilled in the art to which the present invention pertains. Of course, various modifications and variations are possible within the scope of the claims.

1 is a flowchart showing the flow of a wafer cleaning method according to the prior art.

2 is a configuration diagram schematically showing a configuration of an apparatus for cleaning a wafer according to an embodiment of the present invention.

3 is a configuration diagram schematically showing the configuration of another wafer cleaning apparatus used in the embodiment of the present invention.

4 is a flowchart illustrating a flow of a wafer cleaning method according to a preferred embodiment of the present invention.

5 is a flowchart illustrating a wafer cleaning method according to a comparative example, and FIG. 6 is a flowchart illustrating a wafer cleaning method according to an embodiment of the present invention.

Claims (10)

Cleaning the wafer using the SC1 solution; And Cleaning the wafer using gas dissolved water in which gas is dissolved in ultrapure water; Wafer cleaning method characterized in that for removing the particulate and metal contaminants of the wafer at the same time. The method of claim 1, The gas may include any one selected from the group consisting of hydrogen, nitrogen, oxygen, and ozone, or a combination thereof. The method of claim 1, The cleaning of the wafer using the gas dissolved water may include cleaning the wafer using the gas dissolved water to which the alkaline solution is added, and then cleaning the wafer using the gas dissolved water to which the alkaline solution is not added. Wafer cleaning method. The method of claim 3, The alkaline solution is a wafer cleaning method characterized in that it comprises any one or a combination thereof selected from the group consisting of NH ₄ OH, KOH, NaOH, TMAH. The method of claim 1, And cleaning the wafer while applying megasonic to the wafer. Degassing the gas remaining in the ultrapure water; Dissolving gas in the deaerated ultrapure water to produce gas dissolved water; And Cleaning the wafer using the gas dissolved water; Wafer cleaning method comprising a. The method of claim 6, The gas may include any one selected from the group consisting of hydrogen, nitrogen, oxygen, and ozone, or a combination thereof. The method of claim 6, The cleaning of the wafer using the gas dissolved water may include cleaning the wafer using the gas dissolved water to which the alkaline solution is added, and then cleaning the wafer using the gas dissolved water to which the alkaline solution is not added. Wafer cleaning method. The method of claim 8, The alkaline solution is a wafer cleaning method characterized in that it comprises any one or a combination thereof selected from the group consisting of NH ₄ OH, KOH, NaOH, TMAH. The method of claim 6, And cleaning the wafer while applying megasonic to the wafer.

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