Evaporation pretreatment device and method for trace element analysis

Abstract

The present invention relates to an evaporation pretreatment device capable of effectively performing evaporation pretreatment among separation and concentration methods for the analysis of trace elements of high-purity materials. Evaporation pretreatment is a technique for separating a target component to be analyzed from a main component by volatilizing the main component in a sample solution, and relates to a double Teflon evaporation vessel and an independent environment composition structure. The evaporation pretreatment device of the present invention comprises an evaporation vessel, a heating device, an independent environment device, and a volatile substance discharge structure, wherein the evaporation vessel, the heating device, and the independent environment device are assembled inside a clean environment facility in which airflow and exhaust are maintained. An evaporation pretreatment device configured in this manner enables the analysis of ultra-trace elements of high-purity materials.

Description

Technology Field

[0001] The present invention relates to an evaporation pretreatment apparatus capable of effectively performing evaporation pretreatment among separation and concentration methods for the analysis of trace elements of high-purity materials, and an evaporation pretreatment method using the same. Background Technology

[0003] Why Evaporation Pretreatment Is Necessary in Chemical Analysis

[0004] In the chemical analysis of trace element components contained in high-purity materials used in semiconductor processes, methods such as evaporation, solvent extraction, ion exchange, and co-precipitation are used to separate and concentrate the target component from the main component of the sample. These separation and concentration techniques are intended to eliminate matrix effects when the constituent components of the target substance interfere with the process of obtaining a signal from the target component. Furthermore, when it is difficult to distinguish between the background and the signal during the measurement stage, separation and concentration enable the acquisition of reliable quantitative information.

[0005] In solvent extraction, a complexing agent is used to enable inorganic components to dissolve in an organic solvent along with the solvent; in ion exchange, the sample comes into contact with the ion exchange resin; and in coprecipitation, a coprecipitating agent is added. However, since the additives or materials used in these methods contain a certain amount of inorganic elemental components, it is difficult to apply these separation methods to trace analysis. On the other hand, the evaporation method is the most preferred evaluation technique for high-purity materials used in industries such as the semiconductor industry, as the sample does not come into contact with other substances.

[0007] Why Concentration Is Necessary in Chemical Analysis

[0008] The present invention relates to an apparatus and method capable of effectively performing evaporation pretreatment among separation and concentration methods for the analysis of trace elements in high-purity materials. Evaporation pretreatment is a technique that separates the target component to be analyzed from the main component by volatilizing the main component in the sample solution; this has the effect of increasing the concentration of the target component while eliminating interference caused by the main component. Concentration is required when the measurement sensitivity or detection capability of an analytical technique does not meet the analytical objective, or when the background stability of the sample, measurement conditions, or solution is not appropriate relative to the quantitative analysis objective. In particular, when the amount of the target component in the material is less than the quantitative limit of the relevant analytical method, evaporation pretreatment is performed to concentrate the material to a concentration level that ensures reproducibility and reliability. Furthermore, in cases where it is difficult to achieve the quantitative analysis objective due to variability in the measurement background, or where the stability of the measurement background deteriorates due to variability in measurement conditions, concentration can mitigate these problems by amplifying the signal of the target being measured. In this case, it is necessary to minimize variability caused by disturbance during the concentration process. In other words, for effective analysis and evaluation of trace components, it is necessary to avoid being affected by the external environment while simultaneously minimizing signal fluctuations caused by the internal environment.

[0010] Requirements for an evaporation pretreatment device

[0011] The evaporation pretreatment device must be configured to suit the physical and chemical characteristics of the sample, which is the substance to be analyzed. To this end, the present invention distinguishes between high-speed evaporation pretreatment and general evaporation pretreatment based on the purpose of analysis and sample characteristics. When the target component is present in trace amounts in the sample, the evaporation pretreatment device must perform concentration capable of satisfying detection capability indicators, such as the detection limit set according to the purpose of analysis. To achieve this, the device configured according to the present invention must be able to effectively evaporate volatile substances excluding the target component from the sample under appropriate concentration ratio conditions.

[0012] Furthermore, the evaporation pretreatment device must properly discharge volatile substances to prevent leakage toward the experimenter. This also serves to prevent chemical corrosion of the equipment and its surroundings. The evaporation pretreatment device must be able to utilize isolated environmental conditions during the pretreatment process to effectively discharge volatile substances while blocking contamination from the external environment. Additionally, when pretreating multiple samples, the device must prevent cross-contamination between samples and ensure that there is no loss of the target component in the sample, or that such loss is minimized. Moreover, materials or structures that could interfere with the purpose of the analysis must be excluded from the configuration of the device equipped with these functions.

[0014] Related prior art

[0015] Evaporation pretreatment used in the chemical and semiconductor industries, as well as in global environmental research, is generally carried out using heating devices made of ceramic materials; consequently, it is difficult to avoid disturbances caused by chemical corrosion. In particular, since evaporation pretreatment is performed under conditions where it is difficult to completely vent volatile substances, experimenters are frequently exposed to toxic components.

[0016] Methods such as Hong Seong-min's are subject to experimental results determined by the external environment, such as a clean laboratory, and it is difficult to analyze pg / g or lower for elements other than Pb that are prone to contamination, such as Fe, Ca, and Na. Balazs method The evaporation time is long because evaporation occurs under sealed conditions. Additionally, the heating conditions did not achieve the complete exclusion of metal materials. Prior art literature

[0018] U.S. Patent 5,589,005, T. Ohmi (Registered Dec. 31, 1996), "System for supplying ultrapure water and method of washing substitutrate, and system for producing ultrapure water and method of producing ultrapure water" Korean Registered Patent No. 10-1783332 "Clean Lab System for Trace Element Analysis" (Registered Sep. 25, 2017)

[0019] 홍성민 2000, A clean protocol for determining ultralow heavy metal concentrations: its application to the analysis of Pb, Cd, Cu, Zn and Mn in Antarctic snow, Korean Journal of Polar Research 11(1), 35-47Y, Liu, et. al. 2009, The acid cleaning method of labware for trace element analysis in snow and ice samples, Sciences in Cold and Arid Regions 1(6), 502-508C, Boutron 1979, Reduction of contamination problems in sampling of Antarctic snows for trace element analysis, Anal. Chim. Acta 106, 127-130H, Bruce, et. al. 1978, Analysis of high purity chemicals: examination and improvement of the residue after evaporation test for solvents, Anal. Chem. 50(7), 963-964U, Gorlach, et. al. 1990, Preconcentration of lead, cadmium, copper and zinc in water at the pg g-1 level by non-boiling evaporation, Anal. Chim. Acta 236, 391-398S, M, Dhavile, et. al.2007, Development of an in situ evaporation system for the preconcentration of anionic impurities in high purity water, Chromatographia 66, 819-821T, Ohmi 1996, System for supplying ultrapure water and method of washing subtrate, and system for producing ultrapure water and method of producing ultrapure water, US Pat. 5,589,005David Bollinger and Hugh Gotts, MICROELECTRONICS PPQ ANALYSIS OF HIGH-PURITY DI WATER USED IN SEMICONDUCTOR FABS ULTRA PUREWATER NOVEMBER 2007-UP 240813. The problem to be solved

[0020] The present invention aims to provide a device for safely treating volatile substances containing toxic components in most evaporation pretreatment operations.

[0021] In addition, the present invention aims to provide a pretreatment device that prevents chemical corrosion caused by volatile substances and minimizes disturbances caused therefrom.

[0022] In addition, another objective of the present invention is to provide a pretreatment device that enables ultra-trace (sub-ppt: < 1 pg / g) inorganic analysis of high-purity substances by realizing concentration by evaporation pretreatment under conditions that block disturbance. means of solving the problem

[0024] The present invention, aimed at solving the above-mentioned problems, relates to an evaporation pretreatment device capable of effectively performing evaporation pretreatment among separation and concentration methods for the analysis of trace elements in high-purity materials. Evaporation pretreatment is a technique that separates the target component to be analyzed from the main component by volatilizing the main component in the sample solution, and includes a double Teflon evaporation vessel and an independent environment structure. This method enables evaporation pretreatment to be performed under independent environmental conditions that prevent contamination by the external environment. The independent environment not only prevents disturbance by the external environment but also functions to prevent cross-contamination between samples when evaporating multiple sample solutions. The double vessel structure allows for easy removal of contamination from the preceding operation. Compared to a single vessel, this is possible because the outer and inner vessels each perform the function of blocking external contamination, while also allowing for selective and concentrated decontamination of the inner vessel that comes into direct contact with the sample.

[0025] In the evaporation pretreatment device of the present invention, materials that are not contaminated during the pretreatment process are applied to the evaporation vessel, the heating unit, the secondary environment as an independent environment, and the volatile substance exhaust unit. The evaporation vessel, the heating unit, the evaporation workbench, the environmental workbench, and the secondary environment are assembled inside a clean environment facility where airflow and exhaust are maintained. An evaporation pretreatment device configured in this manner enables the performance of trace element analysis of high-purity materials.

[0027] To solve the above problem, the inventors established an isolated environmental condition using a double Teflon evaporation vessel. This method enables evaporation pretreatment to be performed under an isolated environmental condition capable of blocking contamination from the external environment. The isolated environment not only prevents disturbance from the external environment but also functions to prevent cross-contamination between samples when evaporating multiple sample solutions.

[0028] The double container structure allows for easy removal of contamination from the preceding process. Compared to a single container, this is possible because the outer and inner containers each perform the function of blocking external contamination, while also allowing for selective and concentrated decontamination of the inner container that comes into direct contact with the sample.

[0029] In addition, in the configuration of the evaporation pretreatment device of the present invention, materials that do not undergo contamination during the pretreatment process are applied to the evaporation vessel, heating unit, evaporation workbench, and volatile substance exhaust unit. The evaporation vessel, heating unit, and evaporation workbench are assembled inside a clean environment, such as a cleanroom facility, where airflow and exhaust are maintained. An evaporation pretreatment device configured in this manner enables the performance of trace element analysis of high-purity materials.

[0031] The present invention

[0032] A double Teflon evaporation vessel having an upward opening, in which an evaporation reaction of the solution occurs from a solution containing a sample to be measured;

[0033] A heating unit that applies heat to the evaporation vessel from outside the evaporation vessel to turn the solution containing the sample to be measured into an evaporated gas;

[0034] An evaporative gas exhaust unit for exhausting evaporative gas generated inside the above evaporative vessel;

[0035] A shield gas section connected to a shield gas inlet and surrounding the outer periphery of an upper opening of the evaporation vessel, extending further upward than the upper end of the upper opening, and having shield gas supplied to the interior from above to below;

[0036] A shield gas introduction unit connected to the shield gas unit above and introducing shield gas into the shield gas unit;

[0037] An inward-facing shield gas vent that prevents leakage of evaporative gas by introducing shield gas from the shield gas section toward the upward opening of the evaporative vessel and allowing it to flow in the same direction as the evaporative gas flowing upward from the evaporative vessel;

[0038] A shield gas downward exhaust section that allows shield gas to flow out downward from the above shield gas section;

[0039] An evaporation workbench comprising, within it, the evaporation vessel, the heating unit, and the shield gas unit, wherein air flows from above to below and from the inside to the outside, and includes an air purifier equipped with an air purification filter;

[0040] An environment workbench comprising the above-mentioned evaporation workbench inside, wherein air flows from the experimenter's position toward the evaporation workbench;

[0041] The present invention relates to an evaporation pretreatment device for trace element analysis comprising a secondary environment located alongside the above-mentioned environment workbench, into which an experimenter can enter and work, and into which air flows from the center outward to prevent contamination.

[0042] In addition, the present invention relates to an evaporation pretreatment device in which the shield gas is one or more selected from the group consisting of nitrogen, argon, and helium.

[0043] In addition, the present invention relates to an evaporation pretreatment device characterized in that the solution containing the sample to be measured is a high-purity solution.

[0044] In addition, the present invention relates to an evaporation pretreatment device, wherein there are no special limitations on the type of high-purity solution, but, for example, one or more selected from ultrapure water, hydrofluoric acid, nitric acid, and hydrochloric acid.

[0045] In addition, the present invention relates to an evaporation pretreatment device and an evaporation pretreatment method using the same, wherein the rate of the evaporation reaction is controlled by one or more of the following factors: (1) heat supplied by a heating unit, (2) ventilation by a shield gas, (3) a gap between an exhaust unit and an evaporation vessel, and (4) an evaporation surface area.

[0046] In addition, the present invention

[0047] A step of adding a solution containing a sample to be measured to a double Teflon evaporator having an upward opening;

[0048] A heating step using a heating unit that applies heat to the evaporation vessel from outside the evaporation vessel, applying heat below the boiling point of the solution to turn the solution containing the sample to be measured into an evaporated gas through non-boiling evaporation;

[0049] A step of exhausting the evaporated gas generated inside the evaporation vessel through the evaporated gas exhaust port at the top of the evaporation vessel;

[0050] A shield gas upward exhaust step that prevents leakage of evaporative gas by introducing shield gas through a shield gas inlet into a shield gas section that surrounds the side of the evaporative vessel and the outer periphery of the upper opening of the vessel, extends further upward than the upper end of the upper opening, and supplies shield gas internally from the top to the bottom, and introduces shield gas from the shield gas section to a shield gas inner venting section on the side of the evaporative vessel so that the shield gas flows in the same direction as the evaporative gas heading upward from the evaporative vessel; and

[0051] The shield gas downward exhaust step, which prevents leakage of evaporated gas through a shield gas downward exhaust section that allows shield gas to flow from above to below the shield gas section; is included.

[0052] The steps of adding the above solution, heating, evaporated gas exhaust, shield gas upward exhaust, and shield gas downward exhaust are

[0053] An evaporation workbench comprising an air purifier equipped with an air purification filter, wherein air flows from the top downward and from the inside out, and includes the evaporation vessel, the heating unit, and the shield gas unit inside;

[0054] and an environment workbench including the evaporation workbench inside, wherein air flows from the experimenter's position toward the evaporation workbench;

[0055] The present invention relates to an evaporation pretreatment method for trace element analysis, characterized by being performed in an evaporation pretreatment device for trace element analysis that includes a secondary environment located alongside the above-mentioned environment workbench, into which an experimenter can enter and work, and into which air flows from the center outward to prevent contamination.

[0056] In addition, the present invention relates to an evaporation pretreatment method for trace element analysis, characterized in that the pressure above the evaporation surface is maintained at or below the atmospheric pressure level during the heating step.

[0057] In addition, the present invention relates to an evaporation pretreatment method for trace element analysis, characterized in that the evaporation gas exhaust step speed is controlled by one or more of the following factors: (1) heat supplied by a heating unit, (2) ventilation by a shield gas, (3) a gap between the exhaust unit and the evaporation vessel, and (4) an evaporation surface area.

[0058] In addition, the present invention relates to an evaporation pretreatment method for trace element analysis, characterized in that the heating step and the evaporation gas exhaust step are performed at least once at different temperatures or under different conditions depending on the characteristics of the sample and solution to be measured.

[0059] In addition, the present invention relates to an evaporation pretreatment method for trace element analysis, characterized in that, when the solvent of the solution is ultrapure water, the heating step is performed at less than 100°C, preferably at 80°C or higher and less than 100°C, and more preferably at 80°C or higher and less than 90°C.

[0060] In addition, the present invention relates to an evaporation pretreatment method for trace element analysis, characterized in that when the sample to be measured is silicon, the first heating step and the evaporation gas exhaust step are performed at a temperature of less than 120°C, which is lower than the boiling point of the nitric acid solvent and the hydrofluoric acid solvent, and then the second heating step and the evaporation gas exhaust step are performed at a temperature of less than 150°C for SiF4 volatilization.

[0062] Below, we examine in detail the components constituting the evaporation pretreatment device of the present invention.

[0064] Evaporation Pretreatment Device Component 1: Evaporation Vessel

[0065] The present invention is centered around a double Teflon evaporator made of PFA (Perfluoroalkoxy alkanes) and / or PTFE (Polytetrafluoroethylene). The evaporator is connected to an independent environmental device (Fig. 2). The double structure of the Teflon evaporator allows for easy removal of contaminants. In addition, the organic configuration of the evaporator and the heating device minimizes the influence of the external environment. Evaporation is promoted as the surrounding environment is created by the intake and exhaust of volatile components to individual vessels from the top of the evaporator and by a nitrogen flow.

[0067] Evaporation Pretreatment Device Component 2: Heating Unit

[0068] Thermal energy is supplied to the sample through a heating device for evaporation pretreatment of high-purity solutions, etc. High-purity solutions refer to ultrapure water and / or inorganic acids such as hydrofluoric acid, nitric acid, and hydrochloric acid, and the boiling points of these substances are 100-130°C, and evaporation pretreatment is carried out under conditions where the temperature of the solution is below the boiling point.

[0069] Evaporation pretreatment is performed at a temperature of 200°C or lower according to the heating device standards set for each substance to be analyzed. For this purpose, a heating device, preferably a graphite heating device with a Teflon coating, is used. The heating unit, with an evaporation vessel mounted on the top, is connected to an independent environmental device and installed inside the environmental facility (Fig. 2).

[0071] Evaporation Pretreatment Device Component 3: Evaporation Workbench

[0072] The above evaporation vessel and heating device are installed on a dedicated evaporation workbench and configured under conditions that block disturbances caused by the external environment. Nitrogen is supplied to the evaporation workbench to create an independent environment and control the volatilization rate. The workbench is configured to safely discharge volatile substances to the outside. An exhaust structure, such as a fume exhaust system, is installed on the upper part of the evaporation vessel to create an independent environment and facilitate the smooth discharge of volatile substances.

[0073] The evaporator workbench can be manufactured as a tabletop type. There are no specific restrictions on size, but, for example, the standard width is 1200 mm, and the width specifications can be determined within the range of 800 to 1600 mm depending on site space conditions. If it cannot be installed inside a cleanroom, an additional clean environment structure may be applied (Fig. 3). The evaporator workbench includes an air purifier equipped with an air purification filter. There are no specific restrictions on the specifications of the air purifier (FFU: fan filter unit), but, for example, 8 CMM (m²) 3It can be installed based on a standard of / min, and a 12 CMM standard can be applied to match the width standard. The air purification filter equipped in the air purifier can be configured to include, for example, a particle removal filter such as Teflon ULPA and a chemical adsorption filter, and for example, each standard can be 600 × 600 × 75 mm or 600 × 600 × 50 mm, and a separate standard can be set depending on the usage conditions.

[0075] Function 1 of the evaporation pretreatment device of the present invention: Evaporation

[0076] The evaporation pretreatment device of the present invention can control the evaporation rate by heat supplied to the sample, ventilation by nitrogen, and / or the gap between the upper structure and the evaporation vessel. The primary factor of the evaporation function is the thermal energy supplied from the heating device to the evaporation vessel. This causes the sample in a liquid state to vaporize. The evaporation rate is accelerated by the supply of nitrogen. Nitrogen acts as a carrier gas to increase the evaporation rate. Additionally, the upper part of the independent environmental device is connected to the exhaust system, and the appropriate pressure created by inhaling volatile substances accelerates the evaporation rate. Therefore, an appropriate evaporation rate can be set by controlling the temperature of the heating device, the nitrogen gas supply flow rate, and / or the exhaust flow rate of the exhaust system. Along with this, the evaporation surface area can be selected. For example, in the case of silicon analysis, a wide evaporation surface area is used to enable rapid evaporation pretreatment, while in the case of ultrapure water analysis, a narrow evaporation surface area is selected to perform evaporation pretreatment for a relatively long time. In the case of silicon analysis, the ratio of the diameter of the part of the evaporation vessel containing the solution to the diameter of the evaporation surface (i.e., the upper part of the vessel) is 1-0.7, and in the case of ultrapure water, it is 0.7-0.3.

[0077] In addition, in the present invention, it is particularly important that heat is applied at a temperature lower than the boiling point (non-boiling evaporation). For example, in the case of silicon analysis, a mixed solution of nitric acid and hydrofluoric acid is used as a solvent, and while the boiling point of this mixed solution is about 120°C, a lower temperature is applied in the heating section so that the solution evaporates without boiling.

[0079] Function 2 of the evaporation pretreatment device of the present invention: Blocking disturbance caused by contamination

[0080] The double Teflon evaporator vessel can minimize the memory effect of previous operations. By separating the evaporator vessel components, cleaning can be performed not only outside the evaporation pretreatment device, such as a cleaning facility, but also inside the pretreatment facility. Although the structure does not allow for evaporation pretreatment under completely sealed conditions, it creates independent environments for each vessel—namely, the inner and outer vessels. Furthermore, the double evaporator vessel can minimize contamination caused by heating devices and the like.

[0082] Function 3 of the evaporation pretreatment device of the present invention: Prevention of volatile substance leakage

[0083] Volatile substances are discharged using a redundant blocking method. Volatile substances generated in the evaporation vessel are discharged from the top of the independent environmental device toward the exhaust system. Additionally, a shielding function provided by a nitrogen gas supply prevents evaporated substances from escaping to the outside. Furthermore, redundant blocking is maintained by preserving exhaust conditions at the environmental workbench. The airflow conditions at the environmental workbench can also prevent leakage toward the operator. The supply and exhaust airflow rates of the environmental workbench can be set at a fixed ratio. For example, it can be set to maintain a flow rate of 15 CMM for the supply air, or a 2:3 ratio. By setting the exhaust flow rate higher, the possibility of volatile substance leakage can be further reduced.

[0085] Operation 1 of the evaporation pretreatment device of the present invention: Cleaning

[0086] The evaporation vessel itself can be cleaned before performing evaporation pretreatment. There are no specific restrictions on operating conditions, but examples include the following.

[0087] 1. 20% diluted nitric acid, reflux washing at 120°C for 4 hours

[0088] 2. 1% diluted nitric acid, reflux washing at 120°C for 4 hours

[0089] 3. Ultrapure water, reflux washing at 120°C for 4 hours

[0090] This series of cleaning operations can be repeated when necessary, such as immediately before the evaporation pretreatment operation.

[0092] Operation of the evaporation pretreatment device of the present invention 2: Evaporation

[0093] Evaporation pretreatment is classified into high-speed evaporation pretreatment (semi-open evaporation with wide open) and low-speed evaporation pretreatment (semi-open evaporation with narrow open and inert gas purging). Evaporation pretreatment can be performed at less than 2 / 3 of the vessel volume. Typically, 300-350 mL of solution can be evaporated using a 500 mL evaporation vessel, and 600-700 mL of solution can be evaporated using a 1 L evaporation vessel.

[0095] The configuration of the present invention is described in detail below with reference to the drawings.

[0096] In Fig. 1, a liquid such as an evaporating solvent volatilizes and moves upward to reach the suction surface of the exhaust section. As the evaporating material is discharged to the outside, the pressure above the evaporation surface is maintained at or below the atmospheric pressure level.

[0097] A shield gas, such as nitrogen gas, purified through a filter, wraps around the outside of the upper part of the evaporation vessel in a cylindrical shape and flows downward, performing the function of blocking external contamination.

[0098] In addition, a portion of the purified shield gas is drawn into the inner vent of the shield gas along with the volatile evaporating liquid (e.g., solvent) and discharged upward along with the volatile evaporating liquid. At this time, the flow of the shield gas prevents the volatile substances from diffusing outward in directions other than upward.

[0099] The volatilization pressure of the evaporated liquid discharged upward is set to an appropriate condition by controlling the discharge flow rate or controlling the discharge flow rate relative to the suction flow rate.

[0100] The flow rate and velocity of the shield gas are set to appropriate conditions according to the flow rate control of the shield gas inlet.

[0102] In FIGS. 2 and 3, the evaporation workbench (500) is installed inside an up-and-down vertical airflow type clean environment workbench (600). The clean environment workbench (600) can perform the function of removing gaseous ionic components along with purifying fine dust. In addition, for analysis and evaluation work involving boron, which is a semiconductor material quality control item, a purification function for boron components can be added to the evaporation workbench (500).

[0103] The thermal energy required for evaporation is supplied from a heating unit (200), such as a Teflon-surfaced graphite heater. Although it is configured to prevent contamination from metal-contaminating parts such as heater heating elements and electrical supply wiring, the overall airflow of the evaporation workbench (500) is directed from top to bottom to further block the possibility of contamination.

[0104] The outer double Teflon evaporator (101, 102) performs the function of blocking contamination spreading from the heating unit (200).

[0106] In FIG. 3, the secondary environment (700) performs the function of blocking external environmental contaminants that may be delivered to the environmental workbench (600). The same air purification function configuration applied in FIG. 2 is applied to the secondary environment (700). Some of this purified air flows out of the secondary environment (700), and some flows into the environmental workbench (600).

[0107] A portion of the purified air from the environmental workbench (600) is discharged to the outside along with evaporative pretreatment volatile substances and shield gases such as nitrogen. Due to this redundant blocking function, volatile substances are not discharged toward the worker.

[0109] High-speed Evaporation Pretreatment Case Study: Silicon Analysis

[0110] Silicon, which holds the highest technical weight among semiconductor materials, is a high-purity material. The purity of this material is expressed as 9N to 11N (99.9999999% - 99.999999999%), which means that the total content of impurity elements, excluding C and N, exists at a concentration of ppt (pg / g) or lower. ICP-MS, a representative analytical technique used for the elemental analysis of this high-purity material, requires the phase transition of solid silicon into a solution. This dissolution is achieved using a mixed solution of hydrofluoric acid and nitric acid; after dissolution, high concentrations of silicon fluoride, hydrofluoric acid, and nitric acid are present in the sample solution. These components cause interference during the measurement stage, so an evaporation pretreatment is applied to resolve this. During this stage, hydrofluoric acid and nitric acid volatilize, and silicon is removed in the form of volatile fluoride (SiF4). The present invention can be effectively applied for this work, and the evaporation of hydrofluoric acid and nitric acid solutions in the first heating and evaporation step is performed at a temperature below the boiling point of hydrofluoric acid and the boiling point of nitric acid, preferably below 120°C, more preferably between 110°C and 120°C, and then silicon fluoride (SiF4) undergoes high-speed evaporation pretreatment at a relatively higher temperature than the first heating and evaporation step, e.g., 125-140°C (the temperature setting of the heating section is 150-200°C) and at a relatively large evaporation surface area.

[0112] Low-speed Evaporation Pretreatment Case Study: Ultrapure Water Analysis

[0113] Ultrapure water, the most common semiconductor material, is an ultra-high purity material. In ultrapure water used for semiconductor processes, elements that determine the electrical properties of semiconductors, such as Fe and Cu, exist at concentrations below ppt. Since the quantitative limit of the ICP-MS analysis technique, which is most widely used to analyze this, is at the ppt level, ultrapure water samples must be concentrated by more than 10 times before measurement, and evaporation pretreatment is applied for this purpose. The present invention can effectively perform this task by conducting low-speed pretreatment at a relatively low evaporation temperature (the temperature setting of the heating section is 100-150℃) and a relatively narrow evaporation surface area. In conventional technology, the evaporation temperature is at the level of 70-80℃ and the diameter ratio is at the level of 0.3 based on the evaporation solution. In contrast, the present invention uses a double Teflon container, which allows for a wider adjustment range of the diameter ratio; thus, the diameter ratio can be adjusted to the level of 0.7-0.3 while maintaining the same evaporation temperature. Effects of the invention

[0115] The evaporation pretreatment device of the present invention can safely treat volatile substances containing toxic components in most evaporation pretreatment operations.

[0116] In addition, the evaporation pretreatment device of the present invention can prevent chemical corrosion caused by volatile substances, thereby minimizing disturbances caused therefrom.

[0117] In addition, the evaporation pretreatment device of the present invention enables concentration by evaporation pretreatment under conditions that block disturbance, thereby making it possible to analyze ultra-trace amounts (sub-ppt: < 1 pg / g) of high-purity substances. Brief explanation of the drawing

[0119] Figure 1 shows the detailed configuration and function of the evaporation vessel, steam flow, etc. Figure 2 shows the configuration inside the evaporation workbench and the flow of steam. FIG. 3 is a top-down plan showing the configuration of the environmental workbench and secondary environment and the steam flow. Each arrow indicates the gas flow. Specific details for implementing the invention

[0120] The composition of the present invention is described in more detail below with reference to specific embodiments. However, it is obvious to those skilled in the art that the scope of the present invention is not limited only to the description of the embodiments.

[0122] Example 1

[0123] 1. Cleaning Performance Evaluation Procedure

[0124] 1.1. Alcohol (isopropyl alcohol) cleaning was performed to remove organic matter and particle contamination. The cleaning targets included evaporation pretreatment containers and tools such as tongs.

[0125] 1.2. Primary Nitric Acid Reflux Washing (1 st DN Reflux cleaning): 200 mL of 20% distilled grade HNO3 was reflux cleaned in a heating block at 120 ℃ for 4 hours.

[0126] 1.3. Nitric Acid Secondary Reflux Cleaning (2 nd DN Reflux cleaning): 200 mL of 1% distilled grade HNO3 was reflux cleaned in a heating block at 120 ℃ for 4 hours.

[0127] 1.4. Ultrapure Water Primary Reflux Washing (1 st DIW Reflux cleaning): Reflux cleaning was performed for 2 hours in a heating block at 120°C with 200 mL of ultrapure HNO3.

[0128] 1.5. Ultrapure Water Secondary Reflux Cleaning (2 nd DIW Reflux cleaning): Reflux cleaning was performed in 200 mL of ultrapure HNO3 in a 120 ℃ heating block for 2 hours.

[0129] 1.6. Evaluation: 200 mL of ultrapure water was heated in a heating block at 120 ℃ for two hours.

[0131] 2. Method for Calculating Quality Standards

[0132] 2.1. The mean (MEAN) value is the result of ICP-MS measurement of the evaluation solution and is the result with background correction applied.

[0133] 2.2. 1 ppt was applied as the minimum value for ICP-MS analysis.

[0134] 2.3. The BEQ value for cleaning was calculated from the MEAN concentration ppt and the amount of evaluation solution, 200g.

[0135] 2.4. BEQ was calculated as twice the value of the washing BEQ. The BEQ specification is an experimental value determined by the concentration method, from which the washing BEQ = BEQ / 2 is calculated according to the design criteria. However, for this commissioning, the non-concentration method was applied due to the initial operating conditions involving incoming washing, and accordingly, BEQ was calculated from the experimental washing BEQ value.

[0136] 2.5. BEC was calculated from the calculated BEQ value and the amount of evaluation solution, 200g.

[0138] 3. Results

[0139] Na Ca Fe Cu Zn MEAN (ppt) < 1 < 1 < 1 < 1 < 1 Cleaning BEQ (pg) < 200 < 200 < 200 < 200 < 200 BEQ (pg) < 400 < 400 < 400 < 400 < 400 BEC (ppt) < 2 < 2 < 2 < 2 < 2 Explanation of the symbols

[0141] 101, 102: Double Teflon evaporator, 200: Heating section, 300: Exhaust section, 400: Shield Gas Section, 401: Shield gas inlet, 402: Shield gas inner vent, 403: Shield gas downward exhaust, 500: Evaporation Workbench, 600: Environmental Workbench, 700: Secondary environment

Claims

Claim 1 A double Teflon evaporator having an upward opening where an evaporation reaction of the solution occurs from a solution containing a sample to be measured; a heating unit that applies heat to the evaporator from the outside to turn the solution containing the sample to be measured into an evaporative gas; an evaporative gas exhaust unit that exhausts the evaporative gas generated inside the evaporator; a shield gas unit connected to a shield gas inlet unit and surrounding the outer periphery of the upward opening of the evaporator, extending further upward than the upper end of the upward opening, and having shield gas supplied to the interior from the top downward; a shield gas inlet unit connected to the shield gas unit and introducing shield gas into the shield gas unit; a shield gas inner vent unit that prevents leakage of the evaporative gas by introducing shield gas from the shield gas unit toward the upward opening of the evaporator and causing it to flow in the same direction as the evaporative gas heading upward from the evaporator; a shield gas downward exhaust unit that causes the shield gas to flow out downward from the shield gas unit; and including the evaporator, the heating unit, and the shield gas unit inside, and from the top An evaporation pretreatment device for trace element analysis comprising: an evaporation workbench including an air purifier equipped with an air purification filter, through which air flows downward and from the inside to the outside; an environment workbench including the evaporation workbench inside, through which air flows from the experimenter's position toward the evaporation workbench; and a secondary environment located alongside the environment workbench, through which the experimenter can enter and work, through which air flows from the center toward the outside to prevent contamination. Claim 2 An evaporation pretreatment device according to claim 1, wherein the shield gas is one or more selected from the group consisting of nitrogen, argon, and helium. Claim 3 An evaporation pretreatment device according to claim 1, wherein the solution containing the sample to be measured is a solution containing one or more selected from ultrapure water, hydrofluoric acid, nitric acid, and hydrochloric acid. Claim 4 delete Claim 5 An evaporation pretreatment device according to claim 1, wherein the speed of the evaporation reaction is controlled by one or more of (1) heat supplied by a heating unit, (2) ventilation by a shield gas, (3) a gap between an exhaust unit and an evaporation vessel, and (4) an evaporation surface area. Claim 6 A step of adding a solution containing a sample to be measured to a double Teflon evaporation vessel having an upward opening; a heating step using a heating unit that applies heat to the evaporation vessel from the outside, but below the boiling point of the solution, to make the solution containing the sample to be measured into an evaporated gas through non-boiling evaporation; a step of exhausting the evaporated gas generated inside the evaporation vessel through an evaporated gas exhaust part at the top of the evaporation vessel; a shield gas upward exhaust step in which shield gas is introduced through a shield gas inlet part to a shield gas part that surrounds the side of the evaporation vessel and the outer periphery of the upper opening of the vessel, extends further upward than the upper end of the upper opening, and is supplied with shield gas from the top downward, and shield gas is introduced from the shield gas part to a shield gas inner vent part on the side of the evaporation vessel so that the shield gas flows in the same direction as the evaporated gas moving upward from the evaporation vessel to prevent leakage of the evaporated gas. A method for evaporation pretreatment for trace element analysis, comprising: a shield gas downward exhaust step that prevents leakage of evaporated gas through a shield gas downward exhaust section that allows shield gas to flow from above to below the shield gas section; wherein the steps of adding the solution, heating, evaporated gas exhaust, shield gas upward exhaust, and shield gas downward exhaust are performed in an evaporation workbench that includes an air purifier equipped with an air purification filter, which includes the evaporation vessel, the heating section, and the shield gas section inside, and air flows from above to below and from inside to outside; and an environment workbench that includes the evaporation workbench inside and air flows from the position of the experimenter toward the evaporation workbench; and a secondary environment located alongside the environment workbench, into which the experimenter can enter and work, and into which air flows from the center outward to prevent contamination. Claim 7 An evaporation pretreatment method for trace element analysis according to claim 6, characterized in that, in the heating step, the pressure above the evaporation surface is maintained at or below the atmospheric pressure level. Claim 8 An evaporation pretreatment method for trace element analysis according to claim 6, wherein the heating step and the evaporation gas exhaust step are performed at least once at different temperatures or under different conditions depending on the characteristics of the sample and solution to be measured. Claim 9 An evaporation pretreatment method for trace element analysis according to claim 6, characterized in that when the solvent of the solution is ultrapure water, the heating step is performed at less than 100°C. Claim 10 An evaporation pretreatment method for trace element analysis according to claim 6, wherein, when the sample to be measured is silicon, the heating step and the evaporation gas exhaust step are performed at a temperature of less than 120°C, which is lower than the boiling point of the nitric acid solvent and the hydrofluoric acid solvent, and then a secondary heating step and an evaporation gas exhaust step are performed at a temperature of less than 150°C for SiF4 volatilization. Claim 11 An evaporation pretreatment method for trace element analysis according to claim 6, wherein the evaporation gas exhaust step speed is controlled by one or more of the following factors: (1) heat supplied by a heating unit, (2) ventilation by a shield gas, (3) gap between the exhaust unit and the evaporation vessel, and (4) evaporation surface area.

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