JP4947454B2 - Semiconductor processing liquid manufacturing method and manufacturing apparatus thereof - Google Patents

Description

  The present invention relates to a manufacturing method, a manufacturing apparatus, and a manufacturing system of a semiconductor processing liquid containing cyanide ions, which are safe and excellent in industrial productivity.

  An important process in the manufacturing process of a semiconductor substrate is a semiconductor substrate cleaning process, and an RCA processing method (Non-Patent Document 1) is generally widely known as a method for cleaning a semiconductor substrate.

  The RCA treatment method is a technique in which particles and impurity metals adhering to the substrate surface are removed by washing the semiconductor substrate with a solution in which hydrochloric acid, hydrogen peroxide water, ammonia water or the like is mixed. For example, a mixed solution of hydrogen peroxide solution and ammonia solution is effective for removing particles, and a mixed solution of hydrochloric acid and hydrogen peroxide solution is effective for removing impurity metals. However, the RCA treatment method has a complicated process and requires special attention for the maintenance of the solution. Further, since the surface of the semiconductor substrate is etched by the cleaning process, the surface of the semiconductor substrate is roughened, the semiconductor manufacturing process is complicated, or the semiconductor substrate after cleaning has a defect.

On the other hand, one of the inventors has proposed a technique in which a solution containing a cyanide compound is used for cleaning a semiconductor substrate in Patent Document 1 as a means for solving the problems of the RCA treatment method described above. Patent Document 2 proposes a technique of preparing a solution containing cyanide ions by dissolving hydrogen cyanide generated by a reaction between a metal cyanide compound and an acidic solution in a solvent, and using the solution as a semiconductor processing solution. . By this technique, the contaminated metal in the surface region of the semiconductor substrate can be cleaned and removed, and defects in the surface region or surface levels caused by them can be remarkably reduced.
JP 2004-342723 A JP 2005-39198 A RCA Review, June 1970 (Vol. 31) pp. 187-206 Werner Kern, David A. et al. By Putinen, “Cleaning Solutions Based on Hydrogen Peroxide for use in Silicon Semiconductor Technology”

  By using a solution containing cyanide ions (sometimes referred to as cyano ions) for cleaning the surface of a semiconductor substrate, the present inventors can not only remove contaminant metals on the surface but also reduce defects in the semiconductor substrate. Succeeded. However, since the above-described method for manufacturing a semiconductor processing solution has started to attract attention in recent years, many problems still remain regarding industrial productivity for supplying the semiconductor processing solution safely and stably.

  This invention is made | formed in view of this situation, and makes it the main objective to improve the industrial availability of this semiconductor processing liquid. Specifically, it aims at providing the manufacturing method, manufacturing apparatus, and manufacturing system which were excellent in the safety | security and industrial productivity of the semiconductor processing liquid which consists of a solution containing a cyanide ion.

  Inventors examined the manufacturing method of the semiconductor processing liquid containing a cyanide ion in order to solve the above-mentioned subject. Specifically, the inventors focused on a cyanide compound used as a source of cyanide ions. There are non-metallic cyan compounds and metallic cyan compounds as cyan compounds, but non-metallic cyan compounds are extremely expensive. In particular, gasified non-metallic cyan compounds require careful handling due to their danger. Cost.

  However, when a metal cyanide compound is directly used as a supply source of cyanide ions, a base metal (for example, potassium or sodium) is mixed in a solution containing cyanide ions. Unnecessary metal contamination in the solution is undesirable because it contaminates the semiconductor substrate.

  Accordingly, the inventors have ensured safety and generated hydrogen cyanide gas generated by reacting a metal cyanide and an acidic liquid only in a part of the reaction system, and the hydrogen cyanide gas is converted to cyanide ions. It has been found that use as a supply source is suitable for industrial use.

  Based on such knowledge, the inventors have found a method for producing a semiconductor processing liquid that enables hydrogen cyanide gas to be generated using a metal cyanide compound as a starting material, and allows the hydrogen cyanide gas to be contained only in a part of the reaction system, This invention was completed.

  That is, in the present invention, a cyanide compound and an acidic liquid are reacted in an inert gas flow to generate hydrogen cyanide gas, and then the hydrogen cyanide gas is cooled to a boiling point of 25.64 ° C. or lower, and then the cooling is performed. This is a method for producing a semiconductor processing liquid, in which an alkali solution containing cyanide ions is prepared by introducing hydrogen cyanide into an alkaline solution. By reacting a metal cyanide compound with an acidic liquid to generate hydrogen cyanide gas and using this as a direct source of cyanide ions, it is possible to prevent metal from being brought into the solution. In addition, by venting the inert gas, it is possible to prevent the outside air from being mixed and to prevent the generated hydrogen cyanide gas from flowing out of the system, thereby ensuring safety. In addition, by cooling the generated hydrogen cyanide gas to 25.64 ° C. or lower, which is the boiling point of hydrogen cyanide, the hydrogen cyanide gas can be converted into liquid hydrogen cyanide, which increases safety and facilitates handling. The pH of the alkaline solution is preferably more than pH 7 and 12 or less, more preferably 8 or more and 11 or less.

  Moreover, it is desirable to pass through the cooling pipe immediately after the above-described hydrogen cyanide gas is generated. When a cyanide compound and an acidic liquid are reacted, bumping occurs due to an exothermic reaction, and there is a risk that a bumped high-temperature solution is mixed into the alkaline solution. By providing the cooling pipe, it is possible to quickly cool the bumped high temperature solution and prevent it from being brought into the next process. In addition, by cooling with 25.65 ° C. as the lower limit, it is possible to prevent hydrogen cyanide to be sent to the next step from being cooled and liquefied immediately after generation.

  Moreover, you may let the flow path of a labyrinth structure pass instead of a cooling pipe. This is because trapping the bumped solution can prevent it from being brought into the next process. In addition, by cooling the labyrinth-structured flow path at the lower limit value of 25.65 ° C., the same effect as when the cooling pipe is provided can be obtained.

  Moreover, it is preferable to provide the step of introducing hydrogen cyanide gas into ultrapure water between the step of generating the hydrogen cyanide gas and the step of cooling the hydrogen cyanide gas to 25.64 ° C. or lower. By introducing hydrogen cyanide gas into ultrapure water, slight metal impurities (for example, potassium and sodium) entrained in the generated hydrogen cyanide gas can be removed. In order to reduce the amount of hydrogen cyanide gas absorbed into the ultrapure water, it is preferable that the ultrapure water is at room temperature, specifically, 27 degrees to 35 degrees.

  Moreover, it is preferable to introduce hydrogen cyanide gas into the above-described ultrapure water immediately after passing through the backflow prevention device. In the process of introducing the generated hydrogen cyanide gas into ultrapure water, the tip of the pipe to be introduced is installed at a position lower than the interface of ultrapure water. For this reason, it is conceivable that the ultrapure water flows backward, but the reverse flow of ultrapure water can be prevented by passing the hydrogen cyanide gas through the backflow prevention device.

  Moreover, it is preferable that the temperature of the alkaline solution containing the cyanide ions is maintained at 25.64 ° C. or lower. By controlling the temperature of the alkaline solution below the boiling point of hydrogen cyanide, it is possible to prevent the introduced hydrogen cyanide from becoming a gas and flowing out of the solution.

  Moreover, at least 1 sort (s) chosen from the group of a sulfuric acid, phosphoric acid, and perchloric acid can be used for the above-mentioned acidic liquid. By using a strong acid, the reaction with the cyanide is carried out smoothly, and the effect of increasing the production rate of hydrogen cyanide can be obtained.

  Moreover, at least one selected from the group consisting of sodium cyanide, potassium cyanide, cesium cyanide, and rubidium cyanide can be used as the cyan compound.

  The aforementioned solution uses at least one selected from the group of pure water or ultrapure water, alcohols, ketones, nitriles, aromatic hydrocarbons, carbon tetrachloride, ethers, and aliphatic alkanes as a solvent. be able to. Moreover, it is preferable to add at least one of ammonia, choline, and tetramethylammonium hydroxide as the solute of the solution. By adding the solute, the solution can be adjusted to be alkaline.

  Further, it is preferable to introduce the hydrogen cyanide described above into an alkaline solution having an ammonia content that is equal to or greater than the amount that can be replaced with ammonium cyanide by an equivalent reaction. By adding ammonia in excess, hydrogen cyanide in the solution can be positively ionized to supply cyanide ions. Further, as a result of ionization, the concentration of hydrogen cyanide in the solution is prevented from being reduced and vaporized as hydrogen cyanide gas.

  An apparatus for producing a semiconductor processing liquid of the present invention includes a mechanism for venting an inert gas throughout the process, a processing unit for generating a hydrogen cyanide gas by reacting a cyanide compound and an acidic liquid, and the processing unit. A cooling unit that cools the hydrogen cyanide gas by a temperature control device that controls the temperature to 25.64 ° C. or less, and a processing unit that prepares an alkaline solution containing cyanide ions by mixing hydrogen cyanide and an alkaline solution cooled in the cooling unit. It is provided. With this device, it is possible to prevent the outside air from being mixed and to prevent the generated hydrogen cyanide gas from flowing out of the system, thereby ensuring safety. In addition, by cooling the generated hydrogen cyanide gas to 25.64 ° C. or lower, which is the boiling point of hydrogen cyanide, the hydrogen cyanide gas can be made into liquid or solid hydrogen cyanide, which increases its safety and facilitates handling. Moreover, since it introduce | transduces into an alkaline solution after liquefying, the preparation of the processing liquid containing a high concentration cyanide ion is enabled. Furthermore, by introducing hydrogen cyanide into the alkaline solution, hydrogen cyanide can be positively ionized in the solution, cyanide ions can be stably supplied, and a semiconductor processing liquid having high cleaning ability can be supplied.

  Moreover, it is preferable to arrange a cooling pipe for allowing the hydrogen cyanide gas to pass immediately after the processing section for generating the hydrogen cyanide gas. As a result, the bumped hot solution can be quickly cooled and prevented from being brought into the next process. In addition, by cooling with 25.65 ° C. as the lower limit, it is possible to prevent hydrogen cyanide to be sent to the next step from being cooled and liquefied immediately after generation.

  Moreover, you may arrange | position the flow path which has a labyrinth structure instead of a cooling pipe. This is because trapping the bumped solution can prevent it from being brought into the next process. In addition, by cooling the labyrinth-structured flow path at the lower limit value of 25.65 ° C., the same effect as when the cooling pipe is provided can be obtained.

  Further, the processing unit for introducing hydrogen cyanide gas into ultrapure water is provided between the processing unit for generating hydrogen cyanide gas and the cooling unit for cooling by the temperature controller for controlling the hydrogen cyanide gas to 25.64 ° C. or lower. It is preferable. By providing this processing section, metal impurities (for example, potassium and sodium) entrained in the generated hydrogen cyanide gas can be removed. In addition, there exists an effect which prevents the backflow of ultrapure water by providing the backflow prevention apparatus in the process part introduce | transduced into this ultrapure water.

  Moreover, it is preferable to provide the temperature control apparatus which controls an alkaline solution to 25.64 degrees C or less in the process part which prepares the alkaline solution containing the above-mentioned cyanide ion. By controlling the alkaline solution containing cyanide ions below the boiling point of hydrogen cyanide, the introduced hydrogen cyanide can be prevented from becoming a gas and flowing out of the solution.

  It is also possible to construct a system in which a hydrogen cyanide gas trap device including a strong alkaline solution or a mixed solution of strong alkali and hypochlorous acid is provided in a subsequent step of the processing section for preparing the alkaline solution containing cyanide ions. preferable. Even if a slight amount of hydrogen cyanide gas passes through the processing unit for preparing the alkaline solution, the provision of the trap device can prevent the hydrogen cyanide from being discharged out of the system. As a specific strong alkali, it is preferable to use sodium hydroxide or potassium hydroxide. In order to prevent the liquid in the trap device from flowing back to the processing unit for preparing the alkaline solution, it is preferable to provide the trap device with a backflow prevention device.

  According to the semiconductor processing solution manufacturing method, manufacturing apparatus, and manufacturing system of the present invention, hydrogen cyanide, which is a direct source of cyanide ions, is generated from a metal cyanide, and hydrogen cyanide gas that is particularly difficult to handle is contained in the reaction system. Succeeded. Thereby, the manufacturing method, manufacturing apparatus, and manufacturing system of the semiconductor processing liquid containing the cyanide ion which can be utilized industrially were completed.

  Specific embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic diagram illustrating a production apparatus and a production system for producing an alkaline solution containing cyanide ions according to an embodiment of the present invention. Hereinafter, according to FIG. 1, an alkaline solution containing cyanide ions is shown. The process of manufacturing will be described in the order of steps.

  First, nitrogen gas is vented from the upper part of the equal pressure dropping funnel 3 to make the inside of the apparatus a nitrogen atmosphere. Nitrogen is always ventilated during production to prevent outside air contamination and backflow. In this state, a predetermined amount of sulfuric acid prepared by weighing in advance is successively dropped from the isobaric dropping funnel 3 to the Erlenmeyer flask 4. Into the Erlenmeyer flask 4, sodium cyanide equivalent to this sulfuric acid is added and brought into contact with the sulfuric acid to be dropped. Actually, 55 g of sodium cyanide was added to the Erlenmeyer flask 4, and 64 g of concentrated sulfuric acid was diluted with water and added dropwise.

  The produced hydrogen cyanide gas is passed through the cooling pipe 5A. At this time, the cooling pipe 5A was controlled at 27 ° C.

  Next, the hydrogen cyanide gas is liquefied in the process of passing through the cooling pipe 8. At this time, the cooling pipe 8 was cooled to -13 ° C.

  The liquefied hydrogen cyanide is introduced into the product tank 9 to which ammonia water is added, and an aqueous ammonium cyanide solution is generated. At this time, the total amount of liquefied hydrogen cyanide was prepared so as to contain more ammonia than can be replaced by ammonium cyanide, and the pH of the aqueous ammonium cyanide solution was adjusted to pH 8-11. By making the pH of the ammonia water alkaline, ionization of hydrogen cyanide proceeds and a treatment liquid with higher detergency can be prepared. Moreover, when pH is 12 or more, it is not preferable in that ammonia vaporization occurs vigorously. In this embodiment, 28 volume% ammonia water was used so that the alkaline solution in the product tank 9 was a 0.39 volume% ammonia aqueous solution. The aqueous ammonia solution was controlled at 0 ° C. by the cooler 11 and the temperature controller 10.

  Through the above steps, a solution containing cyanide ions could be prepared. In this embodiment, an alkaline solution containing cyanide ions can be produced safely without causing hydrogen cyanide to flow out of the reaction system, and industrial utilization of the present technology becomes possible.

  Further, assuming that a very small amount of hydrogen cyanide gas passed through the product tank 9, a hydrogen cyanide gas removal trap device 13 was provided. As a result, even if hydrogen cyanide passes through the product tank 9, it can be recovered as sodium cyanide by reacting with sodium hydroxide in the trap device 13, which is safer as a whole. Complete manufacturing system. In addition, in order to prevent the solution in the trap device 13 from flowing back into the tank 9, a backflow prevention device 12 is provided immediately before the trap device 13. Through the above manufacturing process, a semiconductor processing liquid containing cyanide ions that can be used industrially was successfully manufactured.

  Next, as another embodiment, after the step of passing the generated hydrogen cyanide gas through the cooling pipe 5A and before the step of passing the cooling pipe 8, the backflow prevention device 6 is passed, FIG. 2 shows a manufacturing apparatus and a manufacturing system provided with a process for introducing the metal removal trap apparatus 7 into ultrapure water. In this embodiment, slight metal impurities such as sodium entrained in the generated hydrogen cyanide gas were removed by passing through the metal removal trap device 7.

  Table 1 shows the metal content (ppb) in the semiconductor processing liquid prepared by the manufacturing method of FIG. Table 2 shows the metal content (ppb) in the semiconductor processing solution prepared by the manufacturing method of FIG. The amount of contained metal was quantified by mass spectrometry using an ICP-Mass device. In Table 1, especially heavy metals such as Cu, Fe, Ni, and Cr, which have side effects on semiconductors, are 0.5 ppb or less, and Na and K are 5 ppb or less. The treated liquid was realized.

  Moreover, in Table 2, Na was suppressed to 1 ppb or less and K was suppressed to 0.1 ppb. By providing a metal removing device or the like, the manufacturing method was further suitable for industrial use.

  Furthermore, as another embodiment, the cooling pipe 5A in the above-described embodiment is replaced with a labyrinth structure 5B, and the cooling pipe 5A is replaced with a labyrinth structure 5C provided with a temperature control device. Is shown in FIG. In these embodiments as well, an alkaline solution containing cyanide ions could be produced safely in the same manner as when the cooling pipe 5A was provided. Moreover, the effect of metal removal was equivalent to the result shown in Table 2.

  As described above, the method of producing a hydrogen cyanide gas using sodium cyanide and sulfuric acid, and cooling the gas and introducing it into ammonia water to produce a semiconductor processing liquid has been described. Instead of the sulfuric acid, phosphoric acid or An acidic liquid typified by perchloric acid may be used. Further, instead of sodium cyanide, a metal cyanide compound represented by potassium cyanide, cesium cyanide or rubidium cyanide may be used. Further, instead of ammonia water, a non-metallic alkaline solution such as choline or tetramethylammonium hydroxide may be used.

  Further, after preparing an alkaline solution containing cyanide ions, dilute hydrofluoric acid, hydrogen peroxide or choline may be added to the solution. A substrate surface more suitable for semiconductor processing can be formed by the etching effect of these additions and the effect of filling defects by cyanide ions.

  In each embodiment, a sodium hydroxide aqueous solution is added into the hydrogen cyanide gas trap device 13. Instead, a strong alkali aqueous solution such as potassium hydroxide or a mixed solution of a strong alkali and hypochlorous acid aqueous solution is added. The same effect was obtained. Further, a step of recovering the cleaning waste liquid from the tank 9 and subjecting the cleaning waste liquid to ozone treatment or ultraviolet light irradiation combined ozone treatment in the recovery device may be added. For the parts and materials used in the manufacturing process, it is optimal to use, for example, a nonmetallic member such as quartz glass in order to avoid contamination.

1 is a schematic diagram illustrating a semiconductor processing liquid manufacturing apparatus and a manufacturing system which are one embodiment of the present invention. 1 is a schematic diagram illustrating a semiconductor processing liquid manufacturing apparatus and a manufacturing system which are one embodiment of the present invention. 1 is a schematic diagram illustrating a semiconductor processing liquid manufacturing apparatus and a manufacturing system which are one embodiment of the present invention. 1 is a schematic diagram illustrating a semiconductor processing liquid manufacturing apparatus and a manufacturing system which are one embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Manufacturing apparatus 2 Manufacturing system 3 Isobaric dropping funnel 4 Erlenmeyer flask 5A, 8 Cooling pipe 5B Flow path which has a labyrinth structure 5C Flow path which has a labyrinth structure provided with a temperature control apparatus 6,12 Backflow prevention apparatus 7 Metal removal trap apparatus 9 Product tank 10 Temperature control device 11 Cooler 13 Hydrogen cyanide gas removal trap device

Claims (21)

In the aeration of inert gas throughout the following processes ,
After producing cyanide gas by reacting cyanide and acidic liquid,
Cooling the hydrogen cyanide gas to 25.64 ° C. or lower;
Thereafter, the cooled hydrogen cyanide is introduced into an alkaline solution in which at least one selected from the group consisting of ammonia, choline, and tetramethylammonium hydroxide is dissolved to prepare an alkaline solution containing cyanide ions. Production method. Immediately after producing the hydrogen cyanide gas, it passes through a cooling tube cooled to a lower limit of 25.65 ° C.,
Thereafter, the cooled hydrogen cyanide gas is cooled to 25.64 ° C. or lower before being introduced into the alkaline solution. Immediately after producing the hydrogen cyanide gas, it passes through the flow path of the labyrinth structure,
The method of manufacturing a semiconductor processing liquid according to claim 1, wherein the hydrogen cyanide gas is then cooled to 25.64 ° C. or lower. The method for producing a semiconductor processing liquid according to claim 3, wherein the flow path of the labyrinth structure is cooled at a lower limit value of 25.65 ° C. 5. Introducing the hydrogen cyanide gas into ultrapure water;
The method for producing a semiconductor processing liquid according to claim 1, provided between the step of generating the hydrogen cyanide gas and the step of cooling the hydrogen cyanide gas to 25.64 ° C. or lower. The generated hydrogen cyanide gas is
The method for producing a semiconductor processing solution according to claim 5, wherein the semiconductor treatment solution is introduced into ultrapure water immediately after passing through the backflow prevention device. The manufacturing method of the semiconductor processing liquid of Claim 1. The temperature of the alkaline solution containing the said cyanide ion is maintained at 25.64 degrees C or less. The method for producing a semiconductor processing liquid according to claim 1, wherein the acidic liquid is at least one selected from the group of sulfuric acid, phosphoric acid, and perchloric acid. The method for producing a semiconductor processing solution according to claim 1, wherein the cyanide compound is at least one selected from the group consisting of sodium cyanide, potassium cyanide, cesium cyanide, and rubidium cyanide. The solvent of the alkaline solution is at least one selected from the group consisting of pure water, ultrapure water, alcohols, ethers, ketones, nitriles, aromatic hydrocarbons, carbon tetrachloride, and aliphatic alkanes. Item 12. A method for producing a semiconductor processing liquid according to Item 1. The method for producing a semiconductor processing liquid according to claim 1, wherein the hydrogen cyanide is introduced into an alkaline solution having an ammonia content equal to or greater than an amount that can be replaced with ammonium cyanide by an equivalent reaction. A mechanism for venting inert gas throughout the following steps;
A treatment unit for reacting a cyanide compound with an acidic liquid to generate hydrogen cyanide gas;
A cooling unit that cools the hydrogen cyanide gas generated in the processing unit by a temperature control device that controls the temperature to 25.64 ° C. or lower;
A process of preparing an alkaline solution containing cyanide ions by mixing hydrogen cyanide cooled in the cooling section and an alkaline solution in which at least one selected from the group consisting of ammonia, choline, and tetramethylammonium hydroxide is dissolved. An apparatus for manufacturing a semiconductor processing liquid comprising a section. A cooling pipe that allows the hydrogen cyanide gas to pass through is disposed immediately after the processing section that generates the hydrogen cyanide gas,
The apparatus for producing a semiconductor processing liquid according to claim 12, wherein the lower limit value of the cooling pipe is controlled to be 25.65 ° C. The apparatus for producing a semiconductor processing liquid according to claim 12, wherein a flow path having a labyrinth structure that allows the hydrogen cyanide gas to pass through is disposed immediately after the processing section that generates the hydrogen cyanide gas. The semiconductor processing liquid manufacturing apparatus according to claim 14, further comprising: a temperature control device configured to control the flow path to 25.65 ° C. or higher in the flow path having the labyrinth structure. A treatment unit for introducing the hydrogen cyanide gas into ultrapure water;
The manufacturing apparatus of the semiconductor processing liquid of Claim 12 provided between the process part which produces | generates the said hydrogen cyanide gas, and the cooling part cooled by the temperature control apparatus which controls the said hydrogen cyanide gas to 25.64 degrees C or less. The apparatus for producing a semiconductor processing liquid according to claim 16, further comprising a backflow prevention device in a processing unit for introducing the hydrogen cyanide gas into ultrapure water. The apparatus for producing a semiconductor processing solution according to claim 12, wherein a temperature control device that controls the alkaline solution to 25.64 ° C. or less is provided in a processing unit that prepares the alkaline solution containing cyanide ions. Furthermore, the hydrogen cyanide gas trap apparatus containing the strong alkali solution or the mixed solution of a strong alkali and hypochlorous acid was provided in the post process of the said process part which prepares the alkaline solution containing the said cyanide ion. Manufacturing equipment for semiconductor processing liquid. The manufacturing apparatus of the semiconductor processing liquid of Claim 19. The said strong alkali solution contains at least 1 sort (s) chosen from sodium hydroxide or potassium hydroxide. The apparatus for producing a semiconductor processing liquid according to claim 19, wherein the hydrogen cyanide gas trap device includes a backflow prevention device.

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