KR102717723B1 - Cleaning method and cleaning apparatus for semiconductor wafers - Google Patents

Abstract

The present invention discloses a method for cleaning a semiconductor wafer and a cleaning device capable of efficiently removing impurities on the surface of a semiconductor wafer even at a low temperature of less than 30°C by immersing the semiconductor wafer in an oxalic acid-containing cleaning solution composition for cleaning.
A method for cleaning a semiconductor wafer according to the present invention comprises the steps of: (a) placing a semiconductor wafer on a pair of roller sections spaced apart from each other such that the longitudinal direction of the rollers and the plane of the semiconductor wafer are perpendicular to each other, and supplying a cleaning composition to a cleaning tank arranged below the roller sections; and (b) cleaning the semiconductor wafer while the roller sections and the semiconductor wafer are immersed in the cleaning composition and the roller sections rotate in the same direction, wherein the cleaning composition contains oxalic acid, hydrogen peroxide (H ₂ O ₂ ), and ammonia water (NH ₄ OH), and in step (b), the semiconductor wafer can be cleaned in the cleaning composition at 20 to 29°C.

Description

CLEANING METHOD AND CLEANING APPARATUS FOR SEMICONDUCTOR WAFERS

The present invention relates to a method for cleaning a semiconductor wafer and a cleaning device capable of efficiently removing impurities on the surface of a semiconductor wafer even at a low temperature of less than 30°C by immersing the semiconductor wafer in an oxalic acid-containing cleaning solution composition for cleaning.

During the process of manufacturing semiconductor devices, a lot of residue or contaminants are generated on the wafer surface.

Residues or contaminants must be removed because they have a particularly significant impact on the performance, reliability, and yield of semiconductor devices by distorting their structural shape and degrading their electrical characteristics.

The semiconductor wafer cleaning technology consists of a step using an alkaline solution and a step using an acidic solution. The alkaline cleaning solution can cause metal contamination on the surface due to its low redox potential, so the metal contamination can be removed through the acidic cleaning solution.

However, in the step of using an acid solution, the surface roughness of the wafer increases due to the toxic strong acid, and re-adsorption of contaminants occurs, which deteriorates the wafer characteristics.

In addition, the process using an acid solution is carried out at a relatively high temperature of 50 to 85℃, and has the disadvantage of not being able to recycle the cleaning solution.

Therefore, there is a need to develop a cleaning process that can perform the wafer cleaning process at a low temperature, prevent re-adsorption of impurities, enable recycling of the cleaning solution, and manufacture high-purity regenerated wafers without etching.

The purpose of the present invention is to provide a cleaning method having excellent cleaning efficiency for semiconductor wafers at a low temperature of less than 30°C.

It is also an object of the present invention to provide a cleaning method having excellent cleaning efficiency for a semiconductor wafer in a short period of time of 10 minutes or less.

It is also an object of the present invention to provide a cleaning method capable of recycling a cleaning liquid composition.

Another object of the present invention is to provide a cleaning method capable of manufacturing a high-purity semiconductor wafer.

In addition, an object of the present invention is to provide a cleaning device having excellent cleaning efficiency for a short period of time of 10 minutes or less at a low temperature of less than 30°C and capable of recycling a cleaning liquid composition.

The purposes of the present invention are not limited to the purposes mentioned above, and other purposes and advantages of the present invention which are not mentioned can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. In addition, it will be easily understood that the purposes and advantages of the present invention can be realized by the means and combinations thereof indicated in the claims.

A method for cleaning a semiconductor wafer according to the present invention comprises the steps of: (a) placing a semiconductor wafer on a pair of roller sections spaced apart from each other such that the longitudinal direction of the rollers and the plane of the semiconductor wafer are perpendicular to each other, and supplying a cleaning composition to a cleaning tank arranged below the roller sections; and (b) cleaning the semiconductor wafer while the roller sections and the semiconductor wafer are immersed in the cleaning composition and the roller sections rotate in the same direction, wherein the cleaning composition contains oxalic acid, hydrogen peroxide (H ₂ O ₂ ), and ammonia water (NH ₄ OH), and in step (b), the semiconductor wafer can be cleaned in the cleaning composition at 20 to 29° C.

Additionally, in the step (b) above, the semiconductor wafer can be cleaned for 3 to 10 minutes.

Additionally, in the step (b), the semiconductor wafer can be cleaned using ultrasonic vibration.

After the above step (b), the cleaning solution composition in the cleaning tank can be moved into the interior of the second filter to remove contaminants contained in the cleaning solution composition.

A semiconductor wafer cleaning device according to the present invention may include a door portion; and a cleaning portion arranged below the door portion, wherein the cleaning portion may include a pair of roller portions spaced apart from each other to rotate a semiconductor wafer arranged vertically; a cleaning tank arranged below the roller portion to accommodate the semiconductor wafer and a cleaning solution composition; and a pump arranged at the rear of the cleaning tank to supply the cleaning solution composition to the cleaning tank.

Additionally, a vibrator may be placed on the lower surface of the cleaning tank.

Additionally, a first filter may be further arranged on the upper surface of the door portion.

Additionally, a pressure valve may be placed in the piping of the above pump.

Additionally, a temperature control unit may be further placed at the rear of the cleaning tank to be connected to the piping of the above pump.

A second filter may be further placed at the rear of the cleaning tank to remove contaminants contained in the cleaning solution composition supplied to the cleaning tank.

The semiconductor wafer cleaning method and cleaning device according to the present invention have an excellent effect of cleaning efficiency of a semiconductor wafer for a short period of time of 10 minutes or less at a low temperature of less than 30°C by immersing the semiconductor wafer in an oxalic acid-containing cleaning liquid composition and then rotating it to clean it.

In addition, the semiconductor wafer cleaning method and cleaning device according to the present invention have the advantage of being able to recycle the cleaning solution composition and manufacture high-purity semiconductor wafers.

In addition to the effects described above, specific effects of the present invention are described below together with specific matters for carrying out the invention.

Figure 1 is a perspective view of a semiconductor wafer cleaning device according to the present invention.
Figure 2 is a plan view of a semiconductor wafer cleaning device according to the present invention.
Figure 3 is a front view of a semiconductor wafer cleaning device according to the present invention.
Figure 4 is a right side view of a semiconductor wafer cleaning device according to the present invention.
Figure 5 is a rear view of a semiconductor wafer cleaning device according to the present invention.
Figure 6 is a drawing showing the types of metal powder, the composition of the cleaning solution, and the experimental conditions.
Figure 7 is a diagram of the formation of a metal complex (complex) by citric acid.
Figure 8 is a diagram of metal complex formation by EDTA.
Figure 9 is a diagram of metal complex formation by oxalic acid.
Figure 10 shows the results of the analysis of the reaction between citric acid and metal powder through UV analysis.
Figure 11 shows the results of the analysis of the reactivity between EDTA and metal powder through UV analysis.
Figure 12 shows the results of the analysis of the reaction between oxalic acid and metal powder through UV analysis.
Figure 13 is a diagram according to the modified SC-1 solution composition and oxalic acid addition.
Figure 14 shows the results of the analysis of the reaction between oxalic acid and metal powder through UV analysis.
Figure 15 shows the results of DLS analysis before and after the reaction.
Figure 16 shows the results of time-dependent ion conductivity analysis.
Figure 17 shows the results of UV, DLS, and time-dependent ionic conductivity analyses before and after the reaction of two metals.
Figure 18 shows the results of UV, DLS, and time-dependent ionic conductivity analyses of three metals before and after the reaction.
Figure 19 shows the results of UV, DLS, and time-dependent ionic conductivity analyses of six metals before and after the reaction.
Figure 20 shows the results of UV, DLS, and time-dependent ionic conductivity analyses of silicon powder before and after reaction.
Figures 21a to 21d show the shape and element analysis results of the contaminated wafer surface.
Figure 22 shows the results of morphology and element analysis of the cleaned wafer surface over time (3, 5, 10 min).
Figure 23 shows the results of particle element analysis of the wafer surface after cleaning.
Figures 24a to 24c show the results of shape and element analysis of the surface of a contaminated wafer (stock wafer).
Figure 25 shows the results of morphology and element analysis of the wafer surface cleaned over time (3, 10 min).
Figure 26 shows the results of morphology and element analysis of the wafer surface cleaned for 3 minutes.
Figure 27 shows the results of shape and element analysis of the wafer surface cleaned for 10 minutes.
Figure 28 shows the composition of the cleaning solution and experimental conditions.
Figure 29 shows the results of shape and element analysis of the contaminated wafer surface.
Figure 30 shows the results of particle element analysis of the wafer surface after cleaning.
Figure 31 shows the results of morphology and elemental analysis of the cleaned wafer surface over time (3, 5, 10 min).
Figure 32 shows the results of particle element analysis of the surface of the wafer cleaned over time (3, 5, 10 min).
Figure 33 shows the experimental conditions according to the composition of the igniter and cleaning solution.
Figure 34 shows the results of particle size changes before and after the reaction between metal star cleaning solutions (H ₂ O ₂ : NH ₄ OH = 8 : 1).
Figure 35 shows the results of particle size changes before and after the reaction between metal-specific cleaning solutions (H ₂ O ₂ : NH ₄ OH = 4 : 1).
Figures 36a and 36b show the results of shape and element analysis of the wafer surface by institution.
Figure 37 shows the results of particle element analysis of the wafer surface after cleaning.
Figure 38 shows the particle measurement results.
Figures 39 to 41 show the results of measuring metal impurities in wafers cleaned by chemtrace.
Figures 42 to 44 show the results of measuring defective particles, polishing rate, and recovery rate of cleaned wafers by KTL, a certification agency.
Figures 45 and 46 show the results of measuring the flatness of a cleaned wafer at KTL, a certification agency.

The above-mentioned objects, features and advantages will be described in detail below with reference to the attached drawings, so that those with ordinary skill in the art to which the present invention pertains can easily practice the technical idea of the present invention. In describing the present invention, if it is judged that a detailed description of a known technology related to the present invention may unnecessarily obscure the gist of the present invention, a detailed description thereof will be omitted. Hereinafter, a preferred embodiment according to the present invention will be described in detail with reference to the attached drawings. In the drawings, the same reference numerals are used to indicate the same or similar components.

Hereinafter, the phrase “any configuration is disposed on (or below)” a component or “on (or below)” a component may mean not only that any configuration is disposed in contact with the upper surface (or lower surface) of said component, but also that another configuration may be interposed between said component and any configuration disposed on (or below) said component.

Additionally, when a component is described as being "connected," "coupled," or "connected" to another component, it should be understood that the components may be directly connected or connected to one another, but that other components may also be "interposed" between the components, or that each component may be "connected," "coupled," or "connected" through other components.

Hereinafter, a semiconductor wafer cleaning method and a cleaning device according to some embodiments of the present invention will be described.

The method for cleaning a semiconductor wafer according to the present invention can exhibit excellent cleaning efficiency at a relatively low temperature for a short period of time using an oxalic acid-containing cleaning liquid composition.

The above cleaning method has the advantage of being able to manufacture high-purity, high-quality wafers.

The method for cleaning a semiconductor wafer of the present invention may include the steps of placing a semiconductor wafer on a pair of roller sections spaced apart from each other such that the longitudinal direction of the rollers and the plane of the semiconductor wafer are perpendicular to each other, supplying a cleaning composition to a cleaning tank arranged below the roller sections, and cleaning the semiconductor wafer while the roller sections and the semiconductor wafer are immersed in the cleaning composition and the roller sections rotate in the same direction.

In the step of supplying the cleaning solution composition to the cleaning tank, the cleaning solution composition can be supplied to the cleaning tank using a pump (bellows pump). A pressure valve is arranged in the pipe of the pump, and the pressure inside the pipe generated when the pump is pumped can be controlled through the pressure valve.

The wet cleaning method using a cleaning solution composition can minimize the problem of oxidation due to the semiconductor wafer not being exposed to the air during cleaning. When the semiconductor wafer is completely immersed in a cleaning tank where the cleaning solution composition is stored and cleaned by the rotation of a roller, the cleaning efficiency can be further increased as the cleaning solution composition comes into contact with the entire surface of the semiconductor wafer.

Since the semiconductor wafer is stably placed on rollers spaced apart from each other, the entire surface of the wafer can be cleaned evenly, and the wafer is balanced so that it can be cleaned in a more stable environment without shaking.

In order to remove impurities and particles remaining on the surface of the semiconductor wafer during the process of slowly lifting the semiconductor wafer after cleaning, a cleaning composition may be sprayed from the upper direction of the wafer toward the plane of the wafer.

It is preferable that the cleaning composition used in the present invention contains oxalic acid, hydrogen peroxide (H ₂ O ₂ ), and ammonia water (NH ₄ OH).

The molar ratio of hydrogen peroxide: ammonia water can be 7:1 to 8:1.

And for 0.33 mol of oxalic acid, it may contain 4 to 6 mol of hydrogen peroxide and 0.5 to 1 mol of ammonia water. Preferably, for 0.33 mol of oxalic acid, it may contain 4.9 to 5.5 mol of hydrogen peroxide and 0.6 to 0.9 mol of ammonia water, and more preferably, it may contain 5.0 to 5.2 mol of hydrogen peroxide and 0.6 to 0.8 mol of ammonia water.

This ratio means that for 1 mol of oxalic acid, it contains 14 to 16 mol of hydrogen peroxide and 1 to 3 mol of ammonia water. In addition, it means that the molar ratio of oxalic acid: hydrogen peroxide: ammonia water is 1:14 to 16:1 to 3, and preferably 1:15 to 16:2 to 3. Since the cleaning solution composition satisfies this ratio, the bonding stability between oxalic acid and metal impurities on the surface of the semiconductor wafer is improved, resulting in a more excellent cleaning efficiency.

In addition, the pH of the detergent composition may be 6 to 7. Since the detergent composition exhibits a relatively strong acid including oxalic acid, it has the advantage of being highly reactive with oxalic acid and all metal impurities, thereby forming a complex compound. In addition, as the reaction between oxalic acid and impurities occurs smoothly, the particle size of all metal impurities decreases, and ionic conductivity may increase.

The temperature of the oxalic acid-containing cleaning solution composition is preferably 20 to 29°C to maintain room temperature, more preferably 22 to 27°C, and even more preferably 23 to 26°C.

And it is preferable to clean the semiconductor wafer for 3 to 10 minutes using an oxalic acid-containing cleaning solution composition, and more preferably to clean it for 5 to 10 minutes.

In the present invention, by using a cleaning composition containing only oxalic acid as a complexing agent, improved cleaning efficiency can be exhibited even when cleaning is performed at a relatively low temperature for a short time.

The cleaning composition can be prepared by mixing and stirring oxalic acid, hydrogen peroxide, and ammonia water at 25±5°C. In addition, in the cleaning process, the amount of the cleaning composition can be adjusted so that the semiconductor wafer can be sufficiently immersed in the cleaning composition.

In the step of cleaning a semiconductor wafer, the semiconductor wafer can be cleaned using sound waves or ultrasonic vibrations.

Specifically, by utilizing a vibrator coupled to the bottom of the cleaning tank, ultra-fine vibrations can be generated in the cleaning solution composition, which can then be transmitted to the wafer surface to maximize the cleaning effect. Using a vibrator, contaminants can be physically removed by the force of sound waves, and many bubbles can be generated by the vibrations, which can remove contaminants from the wafer surface.

For example, a megasonic cleaning method using high frequency having a frequency of 700 to 15,500 kHz, or a method of cleaning without damaging the wafer by vibration using high frequency ultrasonic waves can be performed.

The method for cleaning a semiconductor wafer of the present invention can be performed inside a cleaning device, and can maintain the cleanliness inside the cleaning device by discharging a contaminant to the outside through a first filter disposed on an upper surface of the cleaning device. The first filter includes an FFU/Ulpa filter, and can be manufactured by mounting an ULPA filter on a chamber-shaped Fan Filter Unit.

The ULPA filter is an ultra-high performance filter with a capture efficiency of 99.99% or higher for particles measuring approximately 0.1㎛. The ULPA filter may be selected from either a separator type in which the filter media is folded back and forth to have a pleated shape, or a mini-pleat type in which the media is folded closely, but is not limited thereto.

After the semiconductor wafer cleaning step, impurities and contaminants in the cleaning solution composition can be removed using a tubular second filter.

After cleaning is completed, the cleaning liquid composition contained in the cleaning tank can be moved into the second filter arranged at the rear of the cleaning tank, and the clean cleaning liquid composition discharged from the second filter can be supplied back to the cleaning tank. The cleaning tank and the second filter are connected by a pipe, and the cleaning liquid composition can be moved through the pipe.

In this way, contaminants in a cleaning composition used for cleaning once can be removed, and the cleaning composition from which contaminants have been removed can be recycled.

The second filter can be formed of a cylindrical Teflon (PTFE) material.

In the step of supplying the cleaning composition and the step of cleaning the semiconductor wafer, the temperature of the cleaning composition may be controlled to maintain 20 to 29°C, if necessary, to further maximize the cleaning effect.

In order to control the temperature of the cleaning solution composition, a cylindrical temperature control unit connected to the pump's piping and placed at the rear of the cleaning tank can be used.

The temperature control unit is equipped with a heater and a sensor, so it can exhibit heating and temperature detection functions.

When the temperature of the cleaning solution composition contained in the cleaning tank exceeds 20 to 29°C, the temperature control unit detects the temperature of the cleaning solution composition, and the cleaning solution composition in the cleaning tank can be moved into the temperature control unit. When the temperature of the cleaning solution composition is controlled by the heater inside the temperature control unit and maintained at 20 to 29°C, the cleaning solution composition can be discharged from the temperature control unit and supplied back to the cleaning tank.

In addition, if necessary, the cleaning solution composition stored in the pump can be directly moved to a temperature control unit to maintain the temperature of the cleaning solution composition, and then the cleaning solution composition with the temperature maintained can be supplied to the cleaning tank.

The temperature control unit may be formed of Teflon material to minimize the generation of contaminants.

A semiconductor wafer cleaned by the above cleaning method can exhibit a flatness of 35㎛ or less as measured by contact coordinate measuring machines (KTL equipment), and among the defective particles measured by Tencor-6220, SP-1 equipment and environment (management of 10 class or less), temperature (23±1℃), and humidity (52±2% RH), can exhibit 100 or less of 0.13 to 0.16㎛, 60 or less of 0.16 to 0.2㎛, and 30 or less of 0.2㎛.

Additionally, the cleaned semiconductor wafer can exhibit metal impurities of 5X10 ¹⁰ atoms/cm ² or less as measured by Perkin Elmer DRC IIICPMS equipment.

Additionally, the cleaned semiconductor wafer can exhibit a polishing rate of 1.2㎛/min or higher as measured by Speedfam 50spaw Polisher equipment and digital gauge analysis.

In addition, the cleaned semiconductor wafer can exhibit a recovery rate (1 cassette/batch) of 65% or more of metal contamination on the wafer surface evaluated in the Pilot Plant (Pilot Plant standard (2000*1500*2000), cleaning/rinsing/drying standard (400*600*450 each)).

In this way, by using the cleaning method of the present invention, a high-purity, high-quality regenerated wafer can be manufactured.

A semiconductor wafer cleaning device according to the present invention can exhibit superior cleaning efficiency by utilizing a roller unit that moves a semiconductor wafer in the left-right direction and a cleaning tank that accommodates the cleaning liquid composition.

As shown in FIGS. 1 to 5, the semiconductor wafer cleaning device of the present invention includes a door portion (A) and a cleaning portion (B), and the cleaning portion (B) may include a pair of roller portions (10), a cleaning tank (30), and a pump (50).

The cleaning device has an internal space, and a frame (skeleton) can be arranged on the periphery.

The upper part of the cleaning device may be a door part (A) and the lower part may be a cleaning part (B).

The door section (A) may be formed of a material with transparent sides to allow the user to see through, and a double-door opening type door may be placed on at least one of the sides.

Preferably, a door may be placed in front of the cleaning device. A semiconductor wafer can be mounted or removed from the cleaning section (B) of the cleaning device through the door section (A).

The cleaning unit (B) may include a pair of roller units (10) spaced apart from each other so that the longitudinal direction of the rollers and the plane of the semiconductor wafer are perpendicular to each other in order to clean the semiconductor wafer.

A pair of roller sections can be arranged with a certain interval between them, and additional roller sections can be arranged as needed.

When a semiconductor wafer is placed on a pair of roller sections, cleaning can be performed by rotating the semiconductor wafer, which is placed vertically, while the pair of roller sections rotate in the same direction.

The cleaning unit (B) may include a pair of roller sections, a semiconductor wafer, and a cleaning tank (30) positioned below the roller section to accommodate a cleaning solution composition. The cleaning tank is preferably made of quartz material so as not to be affected by impurities and temperature. The cleaning tank may have a volume larger than the volume of the roller section, and the wafer can be smoothly cleaned within the cleaning tank.

The cleaning unit (B) may include a pump (50) positioned at the rear of the cleaning tank to supply a cleaning liquid composition to the cleaning tank. A pressure valve (55) may be positioned at any location in the pipe of the pump (50), and the pressure inside the pipe may be controlled by the pressure valve (55).

A vibrator (70) may be placed on the lower surface of the cleaning tank (30) to increase the cleaning efficiency of the semiconductor wafer. The vibrator (70) may be operated by a vibrator generator (75) placed on the upper surface of the cleaning device.

A first filter (90) may be additionally placed on the upper part of the door part (A), i.e., the upper surface of the cleaning device. The first filter (90) discharges contaminants generated in the door part (A) and the cleaning part (B) to the outside of the cleaning device, thereby maintaining the cleanliness inside the cleaning device.

A temperature control unit (110) may be further placed at the rear of the cleaning tank (30) to be connected to the pipe of the pump (50). As described above, the temperature control unit (110) is equipped with a heater, a cooler, and a sensor, so that it can exhibit a heating function and a temperature detection function.

After cleaning, the cleaning solution composition contains contaminants, and a second filter (130) placed at the rear of the cleaning tank (30) and on the side of the temperature control unit (110) can be used to remove the contaminants.

The cleaning device of the present invention may have a touch screen (150) placed at the front, preferably placed below the door part (A) and near the cleaning unit (B). The touch screen (150) can control the functions of the roller part (10), the pump (50), the temperature control part (100), etc., and the current operating status inside the cleaning device can be visually checked through the screen.

To control the electric signal of the touch screen (150), a control panel (170) may be placed at the rear of the cleaning device and below the first filter (90) and the vibrator generator (75).

The operating process of the cleaning device is as follows.

First, the user can vertically place a semiconductor wafer on a pair of roller units (10) in the cleaning unit (B) through the door unit (A), and proceed with the cleaning operation of the semiconductor wafer by setting the necessary functions on the touch screen.

For cleaning work, the pump (50) can be operated to supply an oxalic acid-containing cleaning composition to the cleaning tank (30). At this time, the supply amount of the cleaning composition can be controlled by opening and closing the pressure valve (55).

If the temperature of the cleaning solution composition is lower or higher than the target temperature, the cleaning solution composition can be moved to a temperature control unit (110) and heated, and the cleaning solution composition with the temperature maintained can be supplied to the cleaning tank (30).

When the supply of the cleaning solution composition to the cleaning tank (30) is completed, a pair of roller parts (10) rotates, causing the semiconductor wafer to rotate in the same direction as the rotation direction of the roller parts, and cleaning can be performed more smoothly. At this time, the first filter (90) can be operated to maintain the cleanliness inside the cleaning device, and power can be supplied to the vibrator generator (75) to operate the vibrator (70).

When cleaning is complete, the cleaning solution composition in the cleaning tank (30) can be discharged, moved to the second filter (130) to remove contaminants, and then supplied back to the cleaning tank (30) or discharged to the outside.

Hereinafter, specific examples of a semiconductor wafer cleaning method and cleaning device will be examined.

RCA (Radio Corporation of America) cleaning is mainly used in the semiconductor wafer cleaning process.

RCA cleaning cleans wafers through two processes, SC-1 (Standard Clean-1) and SC-2 (Standard Clean-2), which use alkaline solutions and acidic solutions, respectively. In the high pH SC-1 solution, no re-adsorption of metal impurities on the wafer surface occurs, but metal hydroxides are formed, so complete cleaning is achieved through SC-2 cleaning using a strong acid to remove them.

However _, the existing RCA cleaning process has problems in _{that H2O2 decomposition} occurs during the cleaning process, the roughness of the wafer surface increases due to strong acid, and the life of the cleaning tank is shortened due to _H2O2 decomposition by metal impurities, which increases the process cost. In addition, the SC-2 cleaning process adds a process, increases chemical consumption and waste disposal, and has the problem of impurities being re-adsorbed on the wafer surface.

Therefore, a method is needed to remove metal impurities with SC-1 without SC-2 and improve the stability of the cleaning solution.

This problem can be solved by adding a complex to the existing cleaning solution. By adding a complex to the SC-1 solution, the wafer cleaning rate can be improved, cleaning can be performed at room temperature, and cleaning can be performed without _{H2O2 decomposition} and etching.

The mechanism of metal ion complexation according to the complexing agent is the principle of forming a stable compound by forming a chelate ring with the metal ion or removing it through ligand exchange by the carboxyl group (-COOH).

The purpose of the present invention is to develop a technology for cleaning without using strong acids such as hydrofluoric acid and hydrochloric acid.

(1) Analysis and evaluation of cleaning characteristics by variables such as cleaning solution concentration, cleaning time, and temperature.

Figure 6 is a drawing showing the types of metal powder, the composition of the cleaning solution, and the experimental conditions.

As shown in Figure 6, the experiment was conducted by controlling the pH according to the reaction conditions for each complexing agent.

The experiment was conducted until the reaction was visually identifiable (up to 48 hours) under each experimental condition, and the cleaning characteristics were analyzed and evaluated for each variable by measuring UV-vis analysis, particle size analysis, and ionic conductivity. Since the reaction between the complexing agent and the metal powder can be affected by temperature, the ultrasonicator cooling water was continuously circulated to maintain 25℃ and the experiment was conducted.

Impurities on the surface of silicon wafers include Al, Cr, Cu, Fe, Ni, and Zn.

Since various metal impurities are deposited on the contaminated wafer surface, the complexation mechanism of citric acid and oxalic acid, which can react with the most metal impurities, was investigated. Carboxylic acids such as citric acid and oxalic acid are polar chelating agents having electron acceptor (Carbonyl, CO) and electron donor (Hydroxyl, OH) groups, and the combination of the two functional groups in the molecule results in a carboxylic acid functional group. Carboxylic acids are water-soluble and the carboxylate (anionic) form is easily absorbed by metal cations.

In solutions below pH 3, the most stable form of citric acid is HCit ^2- or H ₂ Cit ^- , which can react with copper ions and copper oxides. Citric acid forms stable complexes with metal ions, and also reacts with aluminum cations (Al ³⁺ ) to form soluble complexes.

Oxalic acid also forms stable complexes with metal ions and forms soluble complexes with metals. Oxalic acid also forms complexes with metal cations, and through this, aluminum removal is possible. In addition, previous studies have demonstrated that such complexing agents do not affect the etching of the wafer surface regardless of concentration. Therefore, this study applied such complexing agents to silicon wafer surface cleaning.

(2) Evaluation of the influence characteristics of metal complex compounds according to the type of complexing agent (aminophosphonic acids, condensed phosphoric acids, phenols, etc.)

The complexing agents used in the experiment were citric acid, EDTA (ethylenediaminetetraacetic acid), and oxalic acid, and the experiment was conducted by adding them to a standard SC-1 solution (H ₂ O ₂ : NH ₄ OH : H ₂ O = 1 : 1 : 5).

The evaluation of the complex compound influence characteristics was confirmed through the Pourbaix diagram.

Figure 7 is a diagram of metal complex (complex) formation by citric acid, Figure 8 is a diagram of metal complex (complex) formation by EDTA, and Figure 9 is a diagram of metal complex (complex) formation by oxalic acid.

As can be seen in Figures 7 to 9, since citric acid metal powders (Fe, Cu, Cr, Al, Zn, Ni) react at pH 3, the experiment was conducted by adjusting the pH to 3. In the case of Zn and Cu, dissolution occurred quickly. However, other metal powders, Fe and Al, required more than 48 hours to dissolve, and the dissolution of Cr and Ni could not be identified with the naked eye.

The UV analysis results are as shown in Fig. 10.

As can be seen in Fig. 10, the color change before and after the reaction for each metal powder was visually confirmed, and it is expected that the reaction between citric acid and the powder proceeded smoothly as the absorbance changed greatly. It is expected that the metal powder used in the experiment reacted according to the reaction formula of Fig. 6 and formed a coordination compound between citric acid and the metal.

The formation constant between metal powder and citric acid was determined by examining the effect of citric acid under the assumption that the mass of the reactants and the mass of the products are equal.

As can be seen in Fig. 8, since EDTA and metal powders (Fe, Cu, Cr, Al, Zn, Ni) react at pH 8, the experiment was conducted by adjusting the pH to 8. In the case of Zn and Cu, dissolution occurred quickly, while other metal powders, Fe, Cr, Al, Ni, required more than 24 hours to dissolve, and the UV analysis results accordingly are as shown in Fig. 11.

As can be seen in Fig. 11, color changes before and after the reaction were confirmed for each metal powder. Since the absorbance was confirmed to be significantly different, it is expected that the reaction between EDTA and the metal powder proceeded smoothly. It is expected that the metal powder used in the experiment proceeded with the reaction and formed a coordination compound between EDTA and the metal.

EDTA, like citric acid, was also investigated for the formation constant between metal powder and EDTA under the assumption that the mass of the reactant and the mass of the product are the same. Compared to citric acid, EDTA showed a higher reactivity with metal powder, which is expected to be due to the formation constant and pH effects.

Table 1 shows a comparison of formation constants between metal powders and complexing agents (EDTA, Citric acid).

[Table 1]

Although the formation constant calculated in this experiment and the formation constant from the references show different values, the tendency for EDTA to have a higher formation constant than citric acid was the same.

The formation constant calculated in this experiment is an approximate value calculated under the assumption that all products react and the masses of reactants and products are the same, but it was possible to confirm the effect of EDTA and citric acid on the metal powder. In addition, there was an effect of pH, and the reactivity was low at low pH citric acid and higher at relatively high pH EDTA. This is expected because as pH increases, hydronium ions decrease, which increases the reactivity between metal ions and complexing agents and makes the binding of metal ions more smooth.

As can be seen in Fig. 9, in the case of oxalic acid, metal powders (Fe, Cu, Cr, Al, Zn, Ni) react with oxalic acid at pH 6, so the experiment was conducted by adjusting the pH to 6. In the case of Zn and Cu, dissolution occurred quickly. Other metal powders, Fe and Ni, required more than 12 hours to dissolve, and in the case of Cr and Al, dissolution could not be detected with the naked eye. The UV analysis results according to this are as shown in Fig. 12.

When oxalic acid was added to the standard SC-1 solution, Cr and Al did not react, and the remaining metal powders (Fe, Cu, Zn, Ni) were visually confirmed to dissolve at a faster rate than citric acid and EDTA. In addition, the sample after the reaction showed a higher absorbance than the metal powder before the reaction, so it is expected that the reaction between the complexing agent and the metal powder occurred smoothly.

However, since Cr and Al do not dissolve, the experiment was conducted by controlling the composition ratio of the standard SC-1 solution. The composition ratio of the cleaning solution used in the experiment is oxalic acid (0.33 mol), H ₂ O ₂ (5.115 mol), and NH ₄ OH (0.723 mol).

The evaluation of the characteristics of the complex compound according to this was confirmed through Figure 13.

As shown in Fig. 13, since the metal powder reacts with oxalic acid and the washing solution at pH 7 to form a compound, all metal dissolution experiments were conducted under pH 7. In the case of Zn and Cu, dissolution occurred quickly, and it was visually confirmed that the other metal powders dissolved within 12 hours.

The UV analysis results are as shown in Fig. 14.

As can be seen in Fig. 14, the color change before and after the reaction was confirmed for each metal powder, and it is expected that the reaction between oxalic acid and the metal powder proceeded smoothly since different absorbances were shown in specific wavelength ranges. In addition, the effect of the complexing agent on the metal powder was analyzed through particle size analysis and ionic conductivity measurement before and after the reaction, as shown in Fig. 15.

As shown in Fig. 15, the change in the particle size of the metal before and after the reaction was confirmed for each metal powder. Before the reaction, the metal showed a particle size distribution of 10 μm or more, but after the reaction, it showed a particle size distribution of sub-micron and nano-level. Through this, it is expected that the reaction between the metal powder and oxalic acid occurred, resulting in a decrease in the particle size of the metal powder.

As shown in Fig. 16, it was confirmed that the ionic conductivity also increased continuously over time. The ionic conductivity decreased slightly in the remaining metals except for Fe and Cu. The ionic conductivity before and after 3 hours of reaction showed a slight difference, and since the ionic conductivity did not decrease in Fe and Cu, it is expected that H ₂ O ₂ decomposition was prevented by the complexing agent. It is expected that the metal powder used in the experiment formed a coordination compound between oxalic acid and the metal as the reaction progressed.

Likewise, the formation constant between metal powder and oxalic acid was confirmed to be influenced by oxalic acid under the assumption that the mass of the reactants and the mass of the products are equal.

When experiments were conducted using citric acid, EDTA, and oxalic acid, it took more than 48 hours for citric acid to dissolve all the metals, while in EDTA and oxalic acid, metal dissolution was visually confirmed after 24 and 12 hours, respectively. In addition, although EDTA showed higher absorbance than the existing metal powder in the UV measurement result, it is expected that the dissolution did not occur smoothly because the particle size analysis result showed that there was no difference in the particle sizes of Cr and Fe before and after the reaction.

On the other hand, in oxalic acid, reactions of all metals occurred, and the UV measurement results showed higher absorbance than the existing metal powder, and the DLS analysis results confirmed that the particle sizes of all metals decreased before and after the reaction. The reasons for this include the influence of the binding constant and ionization constant. The binding constant between metals of oxalic acid is higher than that of citric acid and lower than that of EDTA, but the ionization constant (pK _a ) of oxalic acid tends to be lower than those of EDTA and citric acid, which means that oxalic acid is a relatively strong acid compared to EDTA and citric acid. In addition, the reaction rate was slow in citric acid with low pH, and the reaction rate was relatively high in the washing solution containing oxalic acid and EDTA with relatively high pH. This is because as the pH of the complexing agent increases, hydronium ions decrease, increasing the reaction between the metal ions and the complexing agent, which is expected to allow smoother binding of the metal ions.

(3) Analysis of the stability of the bond between the complexing agent and impurities and residues

In order to confirm the bonding stability between the complex and impurities and residues, experiments were conducted by loading the cleaning solution (oxalic acid + H ₂ O ₂ + NH ₄ OH) and 2, 3, and 6 metal powders as above. The bonding stability between the complex and the metal powders was analyzed through UV analysis, ionic conductivity, and DLS.

Figure 17 shows the results of a dissolution experiment conducted by loading two types of metal powders. The UV analysis results show that the absorbance of the metal before and after reaction with the cleaning solution were different, and it is expected that the reaction between oxalic acid and the two metals occurred smoothly. In addition, it was confirmed that the particle size of the metals was significantly reduced after the reaction compared to before the reaction. CuZn, FeAl, and CrNi showed particle size distributions of 10㎛ or more before the reaction, but showed particle size distributions of 50.52nm, 19.6nm, and 5.136㎛ after the reaction, respectively.

For ionic conductivity, all three samples showed a gentle upward curve with a decreasing trend over time, which is expected to be due to the effect of saturation.

Figure 18 shows the results of a melting experiment conducted by loading three types of metal powder.

The UV analysis results showed that the absorbance of the metal before and after reaction with the cleaning solution were different, and it was expected that the reaction between oxalic acid and the three metals occurred smoothly. In addition, it was confirmed that the particle size of the metal was significantly reduced after the reaction compared to before the reaction. FeZnAl and CuCrNi showed particle size distributions of 270.5 nm and 475.4 nm, respectively, after the reaction, from particle size distributions of 10 ㎛ or more before the reaction.

In the case of ionic conductivity, FeZnAl showed a tendency to increase continuously up to 6 hours of reaction, but showed a gentle upward curve from 9 hours. This is expected to be due to the effect of saturation. In the case of CuCrNi, the ionic conductivity showed a tendency to increase from 3 hours to 6 hours. However, the ionic conductivity decreased at 9 hours and showed a tendency to increase at 12 hours. This is expected to be due to the additional dissolution of Cr and Ni, which have slow reaction rates.

Figure 19 shows the results of a melting experiment conducted by loading all metal powders.

The UV analysis results showed that the absorbance of the metal before and after reaction with the cleaning solution were different, and it was expected that the reaction between oxalic acid and the six metals occurred smoothly. In addition, it was confirmed that the particle size of the metal was significantly reduced after the reaction compared to before the reaction. The particle size distribution was 4.8㎛ after the reaction, compared to 10㎛ or more before the reaction.

In the case of ionic conductivity, it decreased after 6 hours, which is expected to be due to saturation. After 12 hours, the ionic conductivity increased again, which is expected to be due to the effects of Cr and Ni, which are slow to dissolve. In addition, an experiment was conducted using silicon powder to confirm the effect of the cleaning solution on the wafer, which is as shown in Fig. 20.

As shown in Fig. 20, the silicon powder showed no difference in absorbance before and after reacting with the cleaning solution in the UV analysis results. The ionic conductivity also showed a lower tendency compared to the existing cleaning solution. However, the DLS particle size analysis results showed a particle size reduction rate, which showed a lower tendency compared to the particle size reduction rates of other metal powders, which is expected to be due to the effects of aggregation and dispersion during the DLS analysis.

Through this, it is expected that the effect of the cleaning solution on the silicon wafer will be small.

Based on these results, wafer cleaning was performed using a cleaning solution prepared at a ratio of (0.33 mol of oxalic acid + 5.115 mol of H ₂ O ₂ + 0.723 mol of NH ₄ OH).

By analyzing the surface morphology and elements of the wafer before and after cleaning, the effect of the cleaning solution on the silicon wafer was confirmed, and the stability of the complexing agent and impurity combination and applicability were analyzed.

Figures 21a to 21d show the surface shape and elemental analysis results of the contaminated wafer.

Analysis of the surface topography of the contaminated wafer confirmed that there were a large number of particles remaining on the surface. Elemental analysis revealed that the particles remaining were Fe, Al, Ca, Ti, Cu, Zn, and organic substances. Si was also detected, but this is believed to have occurred during the wafer sampling process.

In this experiment, the wafer surface was checked at different cleaning times by cleaning for 3, 5, and 10 minutes.

The recovered contaminated wafer sample was cleaned using a cleaning solution (oxalic acid + H ₂ O ₂ + NH ₄ OH). As a result of surface element analysis, as shown in Fig. 22, no secondary phase other than Si was detected, indicating that cleaning was performed smoothly.

As shown in Fig. 23, the surface of the wafer cleaned over time was enlarged, and a small amount of particles were detected on the surface of the wafer, so elemental analysis was performed for each particle.

No secondary phases other than Si were detected on the wafer surface cleaned for 3 minutes, but Al and Ca impurities were detected on the wafer surface cleaned for 5 minutes. However, the content was reduced compared to the Al and Ca contained on the wafer surface before the conventional cleaning, and no impurities other than Al and Ca were detected. When the wafer surface cleaned for 10 minutes was magnified and analyzed, a small amount of particles were detected on the surface, and the component analysis results identified them as Si. It was confirmed that these were Si particles generated during the wafer sampling process, and no secondary phases were detected other than these.

Referring to FIGS. 24a to 24c, the surface topography and elements were analyzed using a second contaminated primary polishing wafer (stock wafer) sample, and residual particles on the surface were identified, which were detected as impurities such as Al, Ca, Mo, and Ti.

Cleaning was performed using the same cleaning solution as in Fig. 22.

Figure 25 shows the surface morphology and elemental analysis results of wafers cleaned for 3 and 10 minutes.

As a result of analyzing the surface elements, as shown in Fig. 25, no secondary phase other than Si was detected, indicating that cleaning was performed smoothly.

Figure 26 shows the results of the morphology and element analysis of the wafer surface cleaned for 3 minutes. In the case of the wafer cleaned for 3 minutes, no secondary phases other than Si were detected, and thus it is expected that the cleaning was performed smoothly. In addition, although there were many particles remaining on the wafer surface in the SEM image, they were detected as Si in the EDS mapping analysis, and it is expected that these are Si particles generated during the wafer sampling process.

Fig. 27 shows the results of the morphology and elemental analysis of the wafer surface cleaned for 10 minutes, and this also did not detect any secondary phases other than Si. In the SEM image, particles remaining on the wafer surface were identified, but the EDS mapping analysis results detected them as Si. These are expected to be Si particles generated during the wafer sampling process. The watermarks on the wafer surface after cleaning are shapes that occurred during the drying process after cleaning. Since the elemental analysis results showed that no secondary phases other than Si existed, the watermarks are shapes unrelated to impurities on the wafer surface, and it is expected that cleaning was performed smoothly through this.

(4) Analysis of wafer surface characteristics according to cleaning process conditions by variable

As shown in Fig. 28, a cleaning solution was prepared by mixing oxalic acid and various complexing agents (citric acid, EDTA) and cleaning of the contaminated wafer was performed. The wafer surface shape and element analysis before and after cleaning were performed to confirm the wafer characteristics according to the cleaning process conditions for each variable.

Fig. 29 is The results of the morphology and element analysis of the contaminated wafer surface. The results of the analysis of the morphology of the contaminated wafer surface confirmed that there were a large number of residual particles on the surface. The results of the element analysis showed that the residual particles were F, S, Cl, Ca, Ti, Mg, Al, and organic substances. Si was also detected, but this is expected to have occurred during the wafer sampling process.

As shown in Fig. 30, the wafer surface cleaned by type of ignition agent was enlarged, and a small amount of particles were detected on the wafer surface, so elemental analysis was performed for each particle. As a result of elemental analysis of the residual particles on the analyzed wafer surface, Ca, Na, Mg, Al, S, and organic substances were detected. The cause of this is expected to be the influence of pH and ionization constant (pK _a ).

The ionization constant (pK _a ) of oxalic acid tends to be lower than that of EDTA and citric acid, which means that oxalic acid is a relatively strong acid compared to EDTA and citric acid. When oxalic acid and citric acid were mixed, the pH was relatively lower than that of the cleaning solution using oxalic acid alone, so the reaction speed was expected to be slow and cleaning would not be smooth.

In addition, when oxalic acid and EDTA were mixed, it was expected that dissolution did not occur smoothly because the protons of the carboxylic acid portion of EDTA were not removed at a relatively low pH, and the electrical interaction with the cleaning solution was reduced, which lowered the solubility.

Therefore, it is considered appropriate to use oxalic acid alone, which has a higher cleaning efficiency than mixed detergents.

(5) Analysis of the behavior of impurity cleaning according to process conditions

To verify the behavior of impurity cleaning according to process conditions, the wafer was cleaned in a cleaning solution containing oxalic acid, hydrogen peroxide, and ammonia water for 3, 5, and 10 minutes, respectively, and the wafer surface was verified according to the cleaning time.

Fig. 31 is This is the result of analyzing the shape and elements of the wafer surface cleaned for 3, 5, and 10 minutes. As a result of the surface element analysis, no secondary phases other than Si were detected, indicating that cleaning was performed smoothly.

As shown in Fig. 32, the surface of the wafer cleaned over time was enlarged, and a small amount of particles were detected on the surface of the wafer. Therefore, elemental analysis was performed for each particle.

S, Ca, Ti, F, Mg, Al, and Fe impurities were detected on the wafer surface cleaned for 3 and 5 minutes. A small amount of particles were detected on the surface when the wafer surface was cleaned for 10 minutes and analyzed by magnification, and the component analysis results identified them as Si. It was confirmed that these were Si particles generated during the wafer sampling process, and no secondary phases were detected. It is expected that the cleaning was performed smoothly.

(6) Analysis and evaluation of the binding stability of impurity elements and complexing agents

In order to verify the stability of the combination of impurity elements and complexing agents, experiments were conducted by loading a cleaning solution and metal powder with a controlled composition ratio as shown in Fig. 33. The composition of the cleaning solution used was changed by conducting the experiment by changing the ratio of H ₂ O ₂ and NH ₄ OH.

The binding stability of the igniter was evaluated using DLS.

As shown in Fig. 34, the particle size change before and after reaction with a cleaning solution (H ₂ O ₂ : NH ₄ OH = 8 : 1) prepared by mixing oxalic acid and EDTA for each metal powder was confirmed.

In the case of Fe, the particle size reduction occurred more smoothly than when oxalic acid alone was added, as shown in Fig. 15. However, in the case of the remaining metal powders, the particle size decreased slightly compared to when oxalic acid alone was added. In particular, in the case of Zn, since there was no difference in particle size compared to other metals, it is expected that dissolution does not occur smoothly.

This is expected to be because EDTA has low solubility in the cleaning solution, so the protons of the carboxylic acid moiety are not removed and the electrical interaction with the cleaning solution is reduced, so dissolution did not occur smoothly compared to the cleaning solution to which oxalic acid alone was added.

In order to further increase the solubility of EDTA, a dissolution experiment was conducted by increasing the _NH4OH ratio of the cleaning solution. Fig. 35 is a graph of particle size changes before and after the reaction between a cleaning solution ( _H2O2 : _NH4OH = ₄ :1) prepared by increasing the _NH4OH ratio in a cleaning solution mixed with oxalic acid and EDTA and a metal powder. The DLS analysis results showed that the particle size change in the cleaning solution with a high _NH4OH ratio was relatively reduced. However, as shown in Fig. 15, the particle size decrease was slightly reduced compared to when oxalic acid was added alone, so it is expected that dissolution did not occur smoothly.

(7) Improvement of cleaning process efficiency through complex compounds for application of regenerated silicon wafers

Figures 36a and 36b show the surface topography and elemental analysis results of silicon wafers by institution. The surface topography analysis results of the contaminated silicon wafers confirmed that there were a large number of particles remaining on the surface. The elemental analysis results showed that the remaining particles were detected as Mg, Al, K, Fe, Ba, Ca, Na, S, Zn, N, Cl, and organic substances. Si was also detected, but this is expected to have occurred during the wafer sampling process.

To establish the efficiency of the cleaning process and the optimal process for applying regenerated silicon wafers, wafers with a large amount of residual impurities among silicon wafers by institution were selected and cleaned.

If the wafer is cleaned using potassium cyanide after wafer cleaning, metal-cyanide ions can be formed. Metal-cyanide ions are stably formed at room temperature due to the strong reactivity of cyanide ions. Cyanide ions form soluble complexes.

Fig. 37 is This is the result of analysis of the wafer surface morphology and elements after cleaning the wafer surface for 10 minutes with the designed cleaning solution (oxalic acid + H ₂ O ₂ + NH ₄ OH) and then additionally cleaning for 10 minutes using a cleaning solution containing potassium cyanide. The analysis results showed that no secondary phases other than Si were detected, indicating that the cleaning was performed smoothly.

(8) Results of property measurement using the cleaning equipment

In order to develop a high-quality regenerated wafer manufacturing technology for the domestic production of semiconductor wafers by manufacturing and installing a cleaning _equipment on site, a wafer cleaning condition evaluation was conducted. The cleaning solution was prepared and used with _H2O2 (5.115 mol) + _NH4OH (0.723 mol) + oxalic acid (0.33 mol). The cleaning condition evaluation was conducted by changing the time and temperature of the prepared cleaning solution, and the optimal cleaning conditions were established by comparing the data before and after cleaning.

The SP1 DLS equipment capable of measuring the number of particles on the wafer after cleaning was used. Fig. 38 shows the particle measurement results according to temperature (room temperature, 30/40/50/60℃) and time (200/250/300/350/400 s).

Even at room temperature, the wafer cleaning power was excellent, so there was a tendency that there was no need to increase the temperature. It is expected that the cleaning was carried out smoothly due to the excellent composition ratio of the oxalic acid-containing cleaning solution composition. The cleaning time showed the most particle removal results at 300 s, so the cleaning time with the highest cleaning efficiency was determined to be 300 s.

The evaluation sampling method for metal contamination on the wafer surface was to sample No. 1 and No. 25 wafers from each cassette after a 3-batch run, measure a total of 6 wafers at Chemtrace, an external organization, and then compile the results and certify them up to the recovery rate at KTL, a certification organization.

Figures 39 to 41 show the results of measuring metal impurities in wafers cleaned by ChemTrace. As a result, all six wafers were confirmed to be normal results, below the quantitative target of 5x10 ¹⁰ atoms/cm ² .

Figures 42 to 44 show the results of measuring defective particles, polishing rate, and recovery rate of cleaned wafers by KTL, a certification agency.

Looking at the number of defective particles, it can be confirmed that there are almost no defective particles as there are 2 or less. The polishing rate is 1.2 ㎛/min or more, and specifically, 1.3 to 2.7 ㎛/min.

Figures 45 and 46 show the results of measuring the flatness of a cleaned wafer at KTL, a certification agency.

Looking at the flat surface, the measured values for five measurement samples ranged from 12.1 to 33.0 ㎛.

In this way, in the present invention, cleaning using a complexing agent was performed to solve problems such as high-temperature cleaning, re-adsorption of impurities, and shortening of the lifespan of the cleaning solution due to _{H2O2 decomposition} .

To confirm the evaluation of the bonding stability between the igniter and the metal, experiments were conducted by mixing two, three, and six types of metal powders into oxalic acid-containing compositions.

All metal powders showed different absorbances before the reaction, in the washing solution, and after the reaction, and a decrease in particle size was observed, indicating that a smooth reaction between the complexing agent and the metal occurred. In addition, since the ionic conductivity increased or slightly decreased before the reaction and 3 hours after the reaction, it is expected that the decomposition of H ₂ O ₂ was prevented through this.

In addition, it was determined that it was appropriate to use oxalic acid alone, as it showed a higher particle size reduction rate and washing efficiency than a washing solution containing citric acid and EDTA mixed with oxalic acid.

Although the present invention has been described with reference to the drawings as examples, it is obvious that the present invention is not limited to the embodiments and drawings disclosed in this specification, and that various modifications can be made by those skilled in the art within the scope of the technical idea of the present invention. In addition, even if the effects according to the configuration of the present invention were not explicitly described while describing the embodiments of the present invention, it is natural that the effects that can be predicted by the corresponding configuration should also be recognized.

A: Door part
B: Tax office
10: A pair of rollers
30: Washing tank
50 : Pump
55 : Pressure valve
70 : Vibrator
75 : Oscillator Generator
90: 1st filter
110 : Temperature control unit
130: Second filter
150 : Touch screen
170 : Control Panel

Claims (10)

(a) a step of placing a semiconductor wafer on a pair of roller sections spaced apart from each other so that the longitudinal direction of the roller and the plane of the semiconductor wafer are perpendicular to each other, and supplying a cleaning solution composition to a cleaning tank arranged under the roller sections; and
(b) a step of cleaning the semiconductor wafer while the roller unit and the semiconductor wafer are immersed in the cleaning solution composition while the roller unit rotates in the same direction;
The above cleaning composition contains oxalic acid, hydrogen peroxide (H ₂ O ₂ ), and ammonia water (NH ₄ OH).
A cleaning method for cleaning a semiconductor wafer in a cleaning solution composition having a temperature of 20 to 29°C in the step (b) above.
In the first paragraph,
A cleaning method for cleaning a semiconductor wafer for 3 to 10 minutes in the step (b) above.
In the first paragraph,
A cleaning method for cleaning a semiconductor wafer using ultrasonic vibration in the step (b) above.
In the first paragraph,
A cleaning method for removing contaminants contained in the cleaning composition by moving the cleaning composition in the cleaning tank into the interior of the second filter after the step (b) above.
A door part; and a cleaning part disposed at the lower part of the door part,
The above cleaning section
A pair of roller units spaced apart from each other to rotate a semiconductor wafer arranged vertically;
A cleaning tank disposed below the roller section to accommodate the semiconductor wafer and the cleaning solution composition;
Including a pump disposed at the rear of the cleaning tank to supply a cleaning solution composition to the cleaning tank;
A cleaning device in which a vibrator is placed on the lower surface of the above cleaning tank.
In paragraph 5,
A cleaning device in which a first filter is further arranged on the upper surface of the door part.
In paragraph 5,
A cleaning device having a pressure valve arranged in the piping of the above pump.
In paragraph 5,
A cleaning device in which a temperature control unit is further placed at the rear of the cleaning tank so as to be connected to the piping of the above pump.
In paragraph 5,
A cleaning device in which a second filter is further arranged at the rear of the cleaning tank to remove contaminants contained in the above cleaning liquid composition.
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