TW201331418A - Method of feeding hydrogen fluoride into an electrolytic cell - Google Patents

Abstract

The invention pertains to a method for supplying hydrogen fluoride as feed material to an electrolytic cell (electrolyzer) for (electrolytically) generating elemental fluorine from a molten salt electrolyte, which comprises transferring hydrogen fluoride (HF) from (a) a hydrogen fluoride supply unit via (b) a hydrogen fluoride supply line to (c) to the electrolytic cell, wherein the required amount of hydrogen fluoride feed for a defined fluorine production capacity is fed into the electrolytic cell, preferably as gaseous HF, with a substantially lower HF feeding quantity per hour (kg/h) over a prolonged feeding interval compared to a full (maximum) HF feeding capacity of 80 kg/h of the supply line and the related short full HF feeding interval, as in hitherto conventional methods. In another aspect the invention also concerns an electrolytic cell for the generation of elemental fluorine by the electrolysis of a molten HF adduct of KF, in which the HF supply line is adapted to the method for supplying hydrogen fluoride as feed material according to the invention.

Description

Method for feeding hydrogen fluoride into an electrolytic cell

The present invention claims the benefit of the European Patent Application No. 1 119 543, filed on Dec. 22, 2011, the entire disclosure of which is hereby incorporated by reference.

The present invention relates to an improved method of supplying hydrogen fluoride as a feed material to an electrolytic cell (electrolyzer) for electrolytically producing elemental fluorine. In particular, such elemental fluorine is intended for supply (delivery) in a method for manufacturing an electronic device.

Hydrogen fluoride is notable useful as a feed material for chemical manufacturing processes such as electrolysis of molecular fluorine (F ₂ ), for example as a chamber cleaning gas system in the semiconductor industry, and for the manufacture of other fluorinated Chemicals such as fluorinated hydrocarbons.

Elemental fluorine (F ₂ ) does not have a GWP (global warming potential) and has no effect on the ozone layer. The elemental fluorine is useful as a fluorinating agent, for example, for producing a polymer fluorinated on a surface, for producing a fluorinated solvent particularly for a Li ion battery, as a chamber cleaner for manufacturing an electronic device, and etching. Agents, such as semiconductors, photovoltaic cells, microelectromechanical systems ("MEMS"), TFTs (thin film transistors for flat panel displays or liquid crystal displays), and the like.

As for the manufacture of electronic devices (especially semiconductors, photovoltaics) The use of etchants for cells, MEMS, and TFTs, several successive steps of depositing multiple layers and etching a portion of them are necessary. Fluorine can be used to etch multiple layers of very different structures, such as for etching layers containing germanium or other layers having compounds that form volatile reaction products such as tungsten. The etching can be performed thermally or plasma assisted.

With regard to the use for chamber cleaning, it is generally carried out in a processing chamber, typically a CVD chamber (a chamber deposited on an article by chemical vapor deposition such as plasma enhanced CVD, metal organic CVD or low pressure CVD). During the deposition process, undesirable deposits are formed on the walls of the chamber as well as on internal structural components and must be removed periodically. This is accomplished by using elemental fluorine as a chamber cleaner to thermally or plasma-enhance the treatment.

Especially for the use of elemental fluorine as an etchant, and also when used as a chamber cleaner, it is desirable that the elemental fluorine is very pure. It is believed that the intrusion of water, carbon dioxide, nitrogen and oxygen is undesirable.

Elemental fluorine can be produced by different methods, but is often produced by electrolysis of hydrogen fluoride (HF) as an electrolytic feed material and an elemental fluorine source as already mentioned above. In the presence of an electrolyte salt, HF releases fluorine if a voltage of at least 2.9 V is applied. In practice, this voltage is typically maintained in the range of 8 to 11 volts.

Typically, one usually has the chemical formula KF. (1.8-2.3) HF, KF molten HF adduct is a preferred electrolyte salt. The HF is fed into a reactor containing the molten electrolyte salt, and F ₂ : 2HF → H _{2 is} electrolytically formed from HF according to the equation (1) by applying a voltage and passing a current through the molten salt. +F ₂ (1)

After the fluorine is produced by electrolytic manufacturing (or any other method), it can be stored in a pressurized cylinder and transported to the point of use. F ₂ of the devices have higher, preferably directly on-site or "over the end of field (over the fence)" F ₂ production.

WO 2004/009873 discloses an apparatus and method for producing fluorine by electrolyzing hydrogen fluoride. The fluorine is produced by electrolysis of HF in a fluorine generating cartridge. The fluorine can be used in the manufacture of electronic devices, for example, in the production of TFTs.

The apparatus includes: a plurality of individual fluorine generating cartridges; the separate fluorine generating cartridges operatively coupled to a fluorine gas distribution system for remote use and consumption of the fluorine gas; The ground is isolated from the gas distribution system and can be removed from the device for remote maintenance. The supply of liquid hydrogen fluoride is kept in a tank according to the comparative document WO 2004/009873. The hydrogen fluoride vaporizer evaporates the liquid hydrogen fluoride in the tank and supplies it to the fluorine generating boxes to maintain the concentration of the electrolyte composed of the aforementioned molten HF adduct of KF.

In the process of electrolysis and elemental fluorine formation, a corresponding amount of hydrogen fluoride (HF) is consumed. Therefore, for the continuous formation of fluorine, fresh HF must be fed into the electrolytic cell from time to time to maintain the level of available HF as a source of fluorine within a certain range, and it is possible to carry out within this range. Electrolysis is performed to produce fluorine with acceptable purity. Normally, for example, in the case of a preferred electrolyte salt of a KF molten HF adduct, the range of HF is generally based on the chemical formula KF. (1.8-2.3) HF to change. At the state of the art, it is quite common to feed a large amount of HF in short intervals, for example to achieve a feed of about 80 kg/h HF or to run the cell at an even higher HF feed rate.

However, the inventors have observed that feeding a large amount of HF in a short interval may cause a problem of maintaining the uniformity of the temperature and composition of the electrolyte throughout the space and time, and as a result, impurities such as CF ₄ , OF ₂ , The formation of O ₂ may increase substantially, resulting in low quality fluorine in terms of its purity. Feeding a large amount of HF in a short interval results in a higher HF concentration, which may result in an excess HF feed that causes the formation of impurities such as OF ₂ , (O ₂ ), CF ₄ , CO ₂ , SO ₂ F ₂ . occur. Also, an increase in current can result in the formation of CF ₄ , CO ₂ , SO ₂ F ₂ . Thereafter, to reduce the level of HF may cause technical problems and thus the carbon anode further formation of undesirable impurities CF ₄ occurs.

For many applications, high purity fluorine or at least very little impurities are required for fluorine, especially in in-situ processes where high purity fluorine, which should be as simple as possible, has low artificial interference, and which requires minimal additional purification, is continuously produced.

Accordingly, it is an object of the present invention to provide a method for feeding HF for the production of fluorine, particularly for producing fluorine having the least impurities, and preferably for high purity. An improved method in a fluorine-containing electrolytic cell. In particular, it is an object of the present invention to provide an improved method in which the temperature can be kept more uniform, the composition of the electrolytic cell is more uniform throughout the space and time, and/or minimized by the method Or preventing the formation of undesirable impurities in the fluorine.

The object of the present invention can be achieved by feeding a modified HF into an electrolytic cell for generating fluorine, as compared to a standard HF feed mode of the state of the art. According to the present invention, HF consumed in electrolysis is compensated by adding a desired amount of fresh HF in a smoother manner over a longer interval. The term "smooth" is intended, for example, to mean less, potentially negative, interference with physicochemical process parameters or electrolytes, thereby maintaining more stable conditions in electrolysis during HF feed, such as maintaining the temperature of the electrolyte. The composition and composition are more uniform throughout the space and time, while at the same time having no negative impact on the production efficiency of fluorine. The term "smooth" also means minimizing or even preventing the formation of impurities.

Accordingly, the present invention provides a method for producing F ₂ in an electrolytic cell (electrolyzer) for producing (electrolytic) elemental fluorine by electrolysis of a molten salt electrolyte through HF contained in the electrolyte, Wherein F ₂ and H _{2 are} formed, and the consumed HF is replenished by supplying fresh HF to produce elemental fluorine from the molten salt electrolyte, including supplying fresh hydrogen fluoride as a feed material to the electrolytic cell (electrolyzer) a step of supplementing the consumed HF, the method comprising transferring hydrogen fluoride (HF) from (a) a hydrogen fluoride supply unit to (b) a hydrogen fluoride supply line to (c) the electrolytic cell, wherein the supply of fresh HF It is limited to a HF flow rate (HF feed amount) of up to 10 kg/h per ton of electrolyte.

Briefly stated, the present invention provides a method for producing F ₂ by electrolyzing HF contained in an electrolyte, wherein F ₂ and H _{2 are} formed, and the consumed HF is supplemented by supply of fresh HF, wherein The supply of fresh HF is limited to a HF flow rate of up to 10 kg/h per ton of electrolyte. Preferably, the HF flow rate is limited to HF up to 5 kg/h per ton of electrolyte. The term "HF flow rate" is interchangeable with the term "HF feed per hour". The term "ton" in the framework of the present invention refers to metric tons. The term "electrolytic cell" is interchangeable with the term "electrolyzer". This element is produced by fluorine electrolysis.

It must be noted that the commonly used apparatus for electrolytically producing F ₂ (substantially equal to the amount of H ₂ produced as a by-product) has an HF consumption of about 1 to 3 kg per ton of electrolyte per hour. Therefore, fresh HF must be supplied at 2 to 6 kg/hr to a device having a capacity of 2 tons of electrolyte to supplement the consumed HF. Typically, such a consumption of a device having a capacity of 2 tons of electrolyte is 3 to 6 kg/hour of HF.

Accordingly, the present invention provides a comprehensive advantage in that although HF is added to the electrolytic cell, the temperature therein can be more easily maintained within a desired predetermined range, and the composition of the electrolyte is more throughout the space and time. Uniform, for example in the entire electrolytic cell (including the feed or entry zone of the HF). A further advantage is that the formation of impurities can be minimized or prevented, so that the fluorine produced requires only limited additional purification measures or the fluorine produced has a purity that is ready for use in the process in which the fluorine will be used.

The term "one/one/one" (a) (for example in a table like "one step" It is not intended to limit the expression to a single step. The term "comprising" encompasses the meaning of "consisting of."

Typically, the HF supply lines are configured for a much higher refill HF flow. For example, the supply lines are configured such that up to 80 kg/h of HF can be introduced into the electrolysis unit. According to the invention, the maximum HF flow rate is considered to be relatively low. Accordingly, the present invention particularly relates to a method for supplying hydrogen fluoride as a feed material to an electrolytic cell (electrolyzer) for producing (electrolytic) elemental fluorine from a molten salt electrolyte, which The method comprises transferring hydrogen fluoride (HF) from (a) a hydrogen fluoride supply unit through (b) a hydrogen fluoride supply line to (c) the electrolytic cell, wherein a desired amount of hydrogen fluoride is fed to a desired amount of fluorine production capacity. A substantially lower, preferably gaseous, hourly HF feed (kg/h) is fed into the cell over a prolonged feed interval compared to 80 kg of the supply line The full (maximum) HF feed capacity of /h and the associated short full HF feed interval (eg, applied to short full HF feed intervals in conventional methods to date).

The hydrogen fluoride (HF) can be fed to the electrolytic cell as a liquid HF feed or as a gaseous HF feed. "Hydrogen fluoride" (HF) is understood to mean in particular anhydrous hydrogen fluoride. When contained in a storage container (a), the hydrogen fluoride is generally liquid. Thus, in the case of a liquid HF feed, the HF can be directly withdrawn from the storage vessel by the required amount and transferred to the electrolytic cell (c) via the supply line (b), for example by pumping or Simply apply pressure to the container and press the HF into the supply line. In the case of a gaseous HF feed, the storage container is attached The additional ground is equipped with an evaporator, and then the liquid HF is evaporated from the storage container (a) and transferred to the electrolytic cell (c) through the supply line (b). When a liquid HF feed is selected, precautions must be taken to avoid blockage (blocking) of the supply line due to sporadic freezing of the molten electrolyte salt in the HF outlet zone, the HF outlet zone extending into the cell Inside the electrolyte. For example, as a guide, a plug at a flow orifice having an inner diameter of about 0.3 mm can be observed. In the case of liquid HF feeds, further precautions must be taken to avoid potential interference with the electrolyte surface. For example, as a guide, a heavily disturbed electrolyte surface at a flow orifice having an inner diameter of about 0.4 mm can be observed. Thus, in this embodiment of the invention the method can be operated at a flow orifice having an inner diameter of about 0.35 mm that can optionally be further adapted to other process parameters.

In a preferred embodiment of the invention, a gaseous HF feed is selected for feeding HF into the electrolytic cell. In this preferred embodiment, the invention thus relates to a method for supplying hydrogen fluoride as a feed material to an electrolytic cell (electrolyzer) for producing (electrolytic) from a molten salt electrolyte Elemental fluorine, the method comprising transferring hydrogen fluoride (HF) from (a) a hydrogen fluoride supply unit through (b) a hydrogen fluoride supply line to (c) the electrolytic cell, wherein a desired amount of fluorine production capacity is required The hydrogen fluoride feed is fed to the electrolysis cell in gaseous HF at a substantially lower hourly HF feed (kg/h) compared to a full (maximum) HF supply capacity over a long period of time. Where the substantially lower HF feed amount is equal to or lower than the full (maximum) feed amount 25%. Preferably, the present invention relates to a method of feeding hydrogen fluoride as a feed material into the electrolysis cell, wherein the full (maximum) feed of the supply line is 80 kg/h and includes an associated short full HF Feed intervals, such as short full HF feed intervals applied to conventional methods to date.

According to the invention, the improved process of the HF feed is related to the manufacture of elemental fluorine. The elemental fluorine in the context of the present invention is produced by electrolysis using hydrogen fluoride (HF) as an electrolytic feed material and the element fluorine source. In the presence of an electrolyte salt, HF releases fluorine if a voltage of at least 2.9 V is applied. In practice, this voltage is typically maintained in the range of 8 to 10 or 11 volts.

The HF is advantageously supplied such that the levels of electrolyte salts and HF in each cell do not exceed a particular upper and lower level. Preferably, the electrolytic cell further includes a sensor that determines the temperature in the cell, the level of liquid in the cell or the cells, pressure or differential pressure, anode current and voltage, and gas temperature. The cells are cooled by cooling water having a temperature of about 80 ° C to 95 ° C.

Typically, a molten HF adduct of KF (preferably having the chemical formula KF. (1.8-2.3) HF) is a preferred electrolyte salt in the context of the present invention. HF is fed into a reactor containing the molten electrolyte salt, and F _{2 is} electrolytically formed from HF according to the above equation (1) by applying a voltage and passing a current through the molten salt.

Accordingly, in one embodiment the invention relates to a method for supplying hydrogen fluoride, wherein the molten electrolyte salt is a KF molten HF adduct, preferably one according to the chemical formula KF. (1.8-2.3) HF has one A molten HF adduct of KF in the HF range.

Typically, in one embodiment the invention relates to a method for supplying hydrogen fluoride, wherein a desired amount of hydrogen fluoride feed associated with the fluorine production capacity of the electrolytic cell, taking into account a device having a capacity of 2 tons of electrolyte, It is in the range of HF feed amount of 2 to 5 kg/h HF, preferably in the range of 3 to 4 kg/h HF.

Typically, in another embodiment the invention relates to a method for supplying hydrogen fluoride, wherein for an apparatus having a capacity of 2 tons of electrolyte, the hourly HF feed (kg/h) is less than 20 kg/h Preferably, it is less than 15 kg/h, and more preferably less than 10 kg/h. In a variation of this embodiment of the invention, the hourly HF feed (kg/h) is in the range of 1 to 20 kg/h per 2 tons of electrolyte, preferably 1 to 15 kg. Within the range of /h, and more preferably in the range of 1 to 10 kg/h. More specifically, the hourly HF feed amount (kg/h) is in the range of 2 to 10 kg/h, preferably in the range of 4 to 10 kg/h, and more preferably in the range of In the range of 6 to 10 kg/h, and even more preferably in the range of 7 to 9 kg/h, and most preferably the hourly HF feed amount is about 8 kg/h per 2 tons of electrolyte. . The term "about" in this context means that the amount of HF feed per hour can vary slightly around the value of 8 kg/h, for example slightly below or slightly above 8 kg/h. Therefore the value may vary by about ±0.5 kg/h, and therefore the HF feed amount is then preferably 8 ± 0.5 kg/h.

A method for supplying hydrogen fluoride to an electrolytic cell for electrolytically producing elemental fluorine from a molten salt electrolyte according to the present invention, The aforementioned hourly HF feed amount (kg/h) can be achieved by several means. For example, in one embodiment of the invention, the hourly HF feed (kg/h) is achieved by adjusting the flow of HF by a pressure or pumping device. Alternatively, the HF feed line has an orifice to reduce the flow of HF. The preferred diameter of the orifice is in the range of 1 mm to 1 cm. This diameter should be related to the amount of HF consumed per unit of time.

A preferred embodiment relates to a device in which HF is supplied to the device in an amount of less than 20 kg/h, typically between 7 and 9 kg/h. Therefore, in this preferred embodiment of the invention, the tube (level sensor) extending into the electrolytic cell (electrolyte) is characterized in that an (inner) diameter in the tube is approximately 2.5 mm. Flow orifice. The term "about" in this context means that a value of 2.5 mm may vary slightly, such as a maximum of ± 0.1 to ± 0.25 mm, preferably ± 0.1 to ± 0.2 mm. Therefore, the flow orifice diameter may be characterized as follows: 2.5 ± 0.25 mm, 2.5 ± 0.2 mm, or 2.5 ± 0.1 mm. It must be noted that the orifice may vary depending on the amount of HF supplied per hour and the inlet pressure of the HF. For an hourly HF supply of more than 20 kg/h, a larger diameter orifice may be useful. For HF supply at a much lower rate than, for example, 6 kg/h, an orifice having a smaller diameter may be advantageous. For a 2.5 mm orifice, the cross-sectional area is approximately 5 mm ² . This cross-sectional area should be related to the amount of HF passing through it per hour. It is assumed that the relationship between the HF feed per hour and the cross-sectional area is linear. It is assumed that if the amount of HF per hour is doubled, an orifice having twice the cross-sectional area should be used. It is assumed that an orifice having a diameter in the range of 1 mm to 1 cm can be used in the supply line. Nonetheless, if it is necessary, an orifice having a smaller or larger diameter can also be used.

In another preferred embodiment of the method for supplying hydrogen fluoride to an electrolytic cell of the present invention, the electrolytic cell is used for electrolytically generating elemental fluorine from a molten salt electrolyte, and HF is fed as a gas to the electrolysis. In the tank, and the hourly HF feed amount (kg/h) is adjusted by the diameter of the flow orifice in the hydrogen fluoride supply line (b), preferably by the hydrogen fluoride supply line (b) This is achieved with a flow orifice with an inner diameter of approximately 2.5 mm. The term "flow orifice" means that the hydrogen fluoride supply line itself may have, and will generally have, a region in the region from the HF storage container to the flow orifice and thereafter into the region of the electrolyte. An inner diameter greater than the 2.5 mm of the flow orifice. For the purposes of the present invention, if there is an inner diameter of such an HF supply line larger than the 2.5 mm inner diameter before and after the flow orifice, it is reduced at the position of the end region of the HF supply line extending into the electrolyte. A diameter of 2.5 mm is completely sufficient. In the broadest sense, this reduction in the inner diameter of the HF supply line can be achieved by any suitable construction means for reducing the inner diameter at a single point within a tube to provide a The required diameter of the orifice.

In still another preferred embodiment of the method for supplying hydrogen fluoride to an electrolytic cell of the present invention, the electrolytic cell is used for electrolytically producing elemental fluorine from a molten salt electrolyte, and the method for supplying hydrogen fluoride The HF feed amount (kg) and the feed interval (h) are adjusted by an automatic valve. Typically, this automatic valve operates under preset conditions and is free to The HF feed parameters are adjusted from time to time during the production of the fluorine, depending on the overall condition of the cell as the electrolysis proceeds over time, for example depending on temperature, HF content, electrolyte level, Current or any other relevant parameter in the electrolysis of the molten salt electrolyte, or the quality of the fluorine produced.

In a preferred embodiment, the maximum possible hourly HF flow rate is greater than the total consumption of HF per hour. For example, the flow rate of the HF is 6 to 10 kg/h, and the consumption of the HF is 2 to 6 kg/h. In this case, the supply flow rate of HF per hour may be larger than the actual consumption amount, and thus the supply of HF may be interrupted within a certain time range. In the absence of HF supply, it is advantageous to introduce an inert gas into the HF feed line. In a preferred embodiment, the electrolyte level is measured in the absence of HF supply. For example, the electrolyte level can be measured in a manner as described in the following paragraphs.

The HF supply line is submerged in the molten electrolyte. Typically, the level of electrolyte in the submerged portion of the supply line is substantially the same as the level of electrolyte surrounding the submerged line. When the supply of the HF is stopped and the inert gas is forced into the submerged supply line, since the pressure of the inert gas prevents the entry of the molten electrolyte, there is substantially no electrolyte in the submerged line. Depending on the level of the molten electrolyte, the pressure of the inert gas must be higher or lower to prevent the electrolyte from entering the submerged line. Relative to the level of electrolyte in the cell, it is possible to calibrate the required pressure in order to prevent the ingress of electrolyte. Depending on the pressure measured, the supply of HF can be adjusted: if the electrolyte level is relatively low, The HF flow rate can be adjusted to a higher value, and/or the supply time can be extended; and if the level is relatively high, the HF flow rate can be adjusted to a lower value, and/or the Supply time can be shortened.

In a preferred embodiment, the ratio of HF flow in kg per hour to HF consumption in kg per hour is between 1.2:1 and 4:1. Preferably, it is between 1.5:1 and 3:1. Therefore, it is possible to provide an interval of HF supply and an interval without HF supply, but the electrolyte level is determined by introducing an inert gas into the supply line as described above. It is preferred to have a fairly frequent HF supply and electrolyte level determination. For example, an HF supply of up to 30 cycles and an electrolyte level determination corresponding to 30 cycles can be predicted per hour. In this case, depending on the ratio of HF flow to consumption, for example, an immediate ratio of 1.2:1, the supply of HF will last for 33 seconds, followed by 27 seconds for level determination, followed by 33 seconds. The HF supply, followed by a 27-second level measurement, and so on. For a 2:1 ratio, a 30 second HF supply will be interrupted for 30 seconds to determine the electrolyte level, and so on. Of course, the expert can schedule the duration of the HF supply and level determination according to his or her wishes. The higher the frequency of the HF the HF feed and delivery period, the more smooth operation of the F ₂ production.

Preferably, the period of the HF feed lasts for example 1 to 60 minutes, 1 to 50 minutes, 1 to 40 minutes, 1 to 30 minutes, 1 to 20 minutes, or 1 to 10 minutes is a practically useful interval; Preferably, a short interval can be selected, for example, an interval of 1 to 5 minutes, preferably 1 to 4 minutes, more preferably 1 to 3 minutes, even more preferably 1 to 2 minutes, and And the best is that the interval of about 1 minute is highly recommended. If the period is measured in seconds, the short interval is, for example, 1 to 60 seconds, 1 to 50 seconds, preferably 20 to 50 seconds, 1 to 40 seconds, preferably 20 to 40 seconds, 1 to 30 seconds, Preferably, about 30 seconds, 1 to 20 seconds, or 1 to 10 seconds are practically useful and recommendable intervals; even shorter intervals may be selected, such as 1 to 5 seconds, 1 to 4 seconds, 1 to 3 seconds, 1 to 2 second intervals, and an interval of about 1 second, but less preferred are such very short intervals. The period in which the HF is not delivered corresponds to the remaining time during the operation of the device.

Of course, it is not necessary to determine the pressure in each interval when there is no HF supply.

Pressure measurement can be performed in the F ₂ chamber of the cell or in the H ₂ chamber. If carried out in the F ₂ chamber (which is preferred), N ₂ or F ₂ is a preferred inert gas. If carried out in the H ₂ chamber (preferably), N ₂ or H ₂ is a preferred inert gas.

In a preferred embodiment, N ₂ or any other inert gas, such as a noble gas, may pass through the HF line or the HF line to prevent molten electrolyte from flowing into the line or lines.

It is even possible to use an automated system to adjust the amount of HF fed, the duration of the HF feed and level measurement, depending on the data provided by this level determination.

In the present invention relating to a method of supplying hydrogen fluoride to an electrolytic cell, the HF can be supplied from any type of hydrogen fluoride storage container. The hydrogen fluoride storage container may be a single hydrogen fluoride reservoir having different sizes. The storage container, or it may be a hydrogen fluoride storage unit comprising a plurality of fixed or optionally transportable hydrogen fluoride storage containers, which may be connected to the electrolyzer via a hydrogen fluoride supply line.

The invention is particularly applicable to a method for producing fluorine, the method comprising supplying hydrogen fluoride to an apparatus, the method comprising (i) filling hydrogen fluoride with at least one transportable hydrogen fluoride storage container, and (ii) storing the hydrogen fluoride The container is delivered to the hydrogen fluoride supply unit, (iii) the hydrogen fluoride storage container is connected to the hydrogen fluoride supply line, and (iv) hydrogen fluoride is supplied from the hydrogen fluoride storage container to the hydrogen fluoride supply line. Preferably, an evaporator for evaporating liquid HF is provided with the hydrogen fluoride storage container, or such an evaporator for evaporating liquid HF is locally available in the device in which the HF is to be supplied for the manufacture of fluorine. Obtained and can be connected to the hydrogen fluoride storage vessel or unit and the hydrogen fluoride supply line. Other additional devices, such as security devices (like HF sensors, HF destruction systems) may also be present at the location of the hydrogen fluoride storage container or device.

In a preferred embodiment, the HF storage containers used in the present invention comprise an automated HF level sensor. In particular, the HF storage containers can be mounted on a scale. In this preferred embodiment, preferably, a program control system, particularly an automatic program control system, is operable to close the remotely controlled valve of the first empty HF container and open another second The remotely controlled valve of the HF hydrogen fluoride storage container. This embodiment is particularly effective for avoiding manual operation of the HF valve and for ensuring a continuous HF supply.

In a preferred aspect, the valves are operable to automatically close in the event of an abnormal operating condition (e.g., a process interruption in a process equipment coupled to the HF supply line).

In another preferred aspect, the valves are operable to automatically close in the event of HF leakage in the hydrogen fluoride supply unit in accordance with the present invention. Such HF leakage may be caused, for example, by leakage of a freely frangible connection inside the HF storage container. This specifically avoids the necessity of approaching the hydrogen fluoride supply unit in this case.

More preferably, the storage containers can be separated from the HF supply line by a double isolation valve having a closed isolation space. In that case, the hydrogen fluoride supply unit according to the invention suitably further comprises at least one gap venting valve connected to the one or more enclosed isolation spaces. The gap vent valve is generally operable to freely remove the hydrogen fluoride present from the enclosed isolated space. Removal can be performed, for example, by applying a vacuum. In another aspect, the removal can be performed, for example, by rinsing the enclosed isolated space using an inert gas and/or a pressurized sweeping gas (e.g., like anhydrous air, preferably nitrogen). In one aspect, this removal is carried out continuously. Preferably, the removal is discontinuous, particularly when an HF storage container is attached to and/or disconnected from the supply line. The gas recovered from the enclosed isolated space is suitably discharged to an HF destruction unit, such as a scrubber, as appropriate.

In an embodiment of the present invention, a method for supplying hydrogen fluoride to electrolytically produce fluorine is characterized in that elemental fluorine produced in the electrolytic cell (c) is intended to be used in a method for manufacturing an electronic device. Use, compare Preferred for use as an etchant or a chamber cleaner in a method for fabricating an electronic device.

In a preferred embodiment of the invention, the method for supplying hydrogen fluoride to electrolytically produce fluorine is characterized in that the electronic devices are selected from the group consisting of semiconductors, photovoltaic cells, MEMS, and TFTs. In an embodiment of the invention, the fluorine is used as a manufacturing electronic device, in particular a semiconductor, a photovoltaic cell, a microelectromechanical system ("MEMS"), a TFT (a thin film transistor for a flat panel display or a liquid crystal display) Room cleaners and etchants. With regard to the use of fluorine as an etchant for the manufacture of electronic devices, particularly semiconductors, photovoltaic cells, MEMS, and TFTs, several successive steps of depositing multiple layers and etching a portion thereof are necessary. Fluorine can be used to etch multiple layers of very different structures, such as for etching layers containing germanium or other layers having compounds that form volatile reaction products such as tungsten. The etching can be performed thermally or plasma assisted. With regard to the use for chamber cleaning, it is generally carried out in a processing chamber, typically a CVD chamber (a chamber deposited on an article by chemical vapor deposition such as plasma enhanced CVD, metal organic CVD or low pressure CVD). During the deposition process, undesirable deposits are formed on the walls of the chamber as well as on internal structural components and must be removed periodically. This is accomplished by using elemental fluorine as a chamber cleaner to thermally or plasma-enhance the treatment.

Especially for the use of elemental fluorine as an etchant, and also when used as a chamber cleaner, it is desirable that the elemental fluorine is very pure. It is believed that the intrusion of water, carbon dioxide, nitrogen and oxygen is undesirable. Produced according to the invention The raw elemental fluorine meets the quality requirements that have been explained in more detail above.

In still another preferred embodiment of the present invention, the method for supplying hydrogen fluoride to electrolytically prepare fluorine is characterized in that the fluorine is "on-site" of a production equipment used in a method for manufacturing the electronic devices or Produced by "crossing the field".

If desired, the fluorine can be produced on site. This is a preferred embodiment of the invention. It can be produced in one or more accessory devices, such as a fluorine-generating cartridge as described in WO 2004/009873. If desired, each cartridge can be assigned to one or more processing chambers in which etching is performed; or a plurality of fluorine-generating cartridges can be coupled to a fluorine gas distribution system coupled to the chambers. The method of low temperature purification of the present invention can be integrated into the cartridge.

After its manufacture and purification, the fluorine is delivered to the point of use. This is preferably carried out at a pressure greater than ambient pressure.

In a preferred embodiment, the fluorine is pressurized by means of a compressor and no pressurized gas is used (unless it is elemental fluorine).

This storage step (if foreseen) preferably means that the elemental fluorine is stored in a suitable canister such as a stainless steel bottle.

Preferably, the fluorine is produced at its point of use by electrolysis in an apparatus that is in fluid communication with the process chamber or process chambers. This means that the produced elemental fluorine is not filled into one or more pressurized bottles that are subsequently disconnected from the delivery line. If desired, the fluorine is only stored in a plurality of cans or bottles that remain attached to the delivery line. Often, the fluorine generator is positioned in the same way as the tools in which it is used On the device, i.e., a distance of less than 500 m from the manufacturing tool; the generator is often positioned adjacent to the tool, i.e., a distance of 100 m or less from the tools. It is even possible to position them in the vicinity of the process chamber as a point of use, for example the distance may be 10 m or less.

The step of delivering preferably means passing fluorine through the conduit, particularly through the conduit that remains permanently connected, from the manufacturing appliance to the point of use to prevent ingress of air into the fluorine and to prevent leakage of fluorine.

In another aspect, the invention also relates to an electrolytic cell for producing elemental fluorine by electrolyzing a molten HF adduct of KF, wherein the electrolytic cell (c) is provided with a hydrogen fluoride which can be connected to the hydrogen fluoride supply unit (a) Supply line (b), and wherein the hydrogen fluoride supply line (b) has a flow orifice having an inner diameter of about 2.5 mm. The term "flow orifice" and the nature and means of achieving the inner diameter have been described in the context of the above method of supplying HF to an electrolytic cell for the manufacture of elemental fluorine. The description and description given above are equally applicable to this aspect of the invention relating to an electrolytic cell for producing elemental fluorine by electrolyzing a molten HF adduct of KF.

In a preferred embodiment of the invention for use in an electrolytic cell for producing elemental fluorine by electrolysis of fluorine, the fluorine is in a cartridge, preferably for use in an electronic device (preferably for selection) Production equipment for free-semiconductor, photovoltaic cells, MEMS, and electronic devices of the group of TFTs is produced "on-site" or in a box that produces fluorine over the field end. The concept and essence of the “on-site” or “crossing obstacles” of production equipment have been The description of the method of supplying HF to an electrolytic cell for producing elemental fluorine is described. The description and description given above are equally applicable to this aspect of the invention relating to an electrolytic cell for producing elemental fluorine by electrolyzing a molten HF adduct of KF.

In still another preferred embodiment of the present invention for producing an electrolytic cell for producing elemental fluorine by electrolyzing fluorine by electrolyzing a molten HF adduct of KF, an electrolytic cell is provided to obtain 50 to 100 kg of fluorine ( The daily (24 h) production capacity of F ₂ ), preferably the daily (24 h) production capacity of 80 to 100 kg of fluorine (F ₂ ), more preferably about 80 to 90 kg of fluorine (F ₂ ) Daily (24 h) production capacity.

The following examples are intended to illustrate the invention in detail and not to limit it.

Example 1: Feeding gaseous HF into an electrolytic cell for the production of elemental fluorine

Will have an approximate KF. The electrolyte salt composed of 2HF is filled in an electrolytic cell, heated to about 80 ° C to 120 ° C and melted therein. Gaseous HF was introduced into the electrolytic cell through an HF supply line having an inner diameter of 2.5 mm and an HF feed per hour of about 8 kg/h. The HF feed (kg) and feed interval (h) are adjusted by an automatic valve to provide a feed of 3 to 4 kg/h HF taking into account the capacity of the cell. A voltage between 8 and 10 V is applied and the current is passed through the composition of the electrolyte salt dissolved in the hydrogen fluoride; the contents of the cell are maintained in the range of about 80 °C to 100 °C. Elemental fluorine and elemental hydrogen are formed in the respective electrode chambers. The resulting elemental fluorine is passed through a Monel alloy frit to remove solids and pressurized to about 10 bar absolute by means of a compressor and then passed through a trap cooled to -80 ° C; in this trap, entrained The HF condensed. The gaseous F ₂ leaving the trap is passed through a bed of NaF to remove any remaining HF.

During the interval in which the HF supply is stopped, the level of the electrolyte is determined by pressing N ₂ gas into the HF supply line. The supply of HF is reduced, increased or remains constant depending on the level of electrolyte measured.

In the event that any disclosure of patents, patent applications, and publications incorporated by reference is inconsistent with the present disclosure, and the extent of such conflicts renders the term unclear, the present description should be preferred.

Claims (18)

A method for producing F ₂ in an electrolytic cell (electrolyzer) for producing (electrolytic) elemental fluorine (electrolytic) from a molten salt electrolyte by electrolyzing HF contained in the electrolyte, wherein F ₂ and H ₂ and the consumed HF is replenished by supplying fresh HF to produce elemental fluorine from the molten salt electrolyte, including a step of supplying fresh hydrogen fluoride as a feed material to the electrolytic cell (electrolyzer) The HF consumed, the method comprising transferring hydrogen fluoride (HF) from the (a) hydrogen fluoride supply unit through the (b) hydrogen fluoride supply line to (c) the electrolytic cell, wherein the supply of fresh HF is limited to each ton of electrolyte HF flow rate (HF feed amount) of up to 10 kg/h HF. The method of claim 1, wherein a molten salt electrolyte is electrolyzed, and wherein the molten salt electrolyte is a KF molten HF adduct, preferably one according to the chemical formula KF. (1.8-2.3) HF KF molten HF adduct having a range of HF. The method of claim 1, wherein the required amount of hydrogen fluoride in relation to the fluorine production capacity of the electrolytic cell is in the range of 2 to 5 kg/h HF of the HF feed amount relative to 2 tons of the electrolyte. Preferably, it is in the range of 3 to 4 kg/h HF. The method of claim 3, wherein the hourly HF feed amount (kg/h) is less than 15 kg/h, more preferably less than 10 kg/h, per 2 tons of electrolyte. The method of claim 3, wherein the hourly HF feed amount (kg/h) is in the range of 1 to 20 kg/h, preferably 1 It is in the range of 15 kg/h, and more preferably in the range of 1 to 10 kg/h. The method of claim 5, wherein the hourly HF feed amount (kg/h) is in the range of 2 to 10 kg/h, preferably in the range of 4 to 10 kg/h, And more preferably in the range of 6 to 10 kg/h, and even more preferably in the range of 7 to 9 kg/h, and most preferably the hourly HF feed amount is about 8 kg/ h. The method of claim 1, wherein the hourly HF feed amount (kg/h) is achieved by adjusting the flow rate of the HF by a pressure or pumping device. The method of claim 1, wherein the hourly HF feed amount (kg/h) is adjusted by adjusting a diameter of a flow orifice in the hydrogen fluoride supply line (b), preferably by The hydrogen fluoride supply line (b) is realized by a flow orifice having a diameter of about 2.5 mm. The method of claim 8, wherein the HF feed amount (kg) and the feed interval (h) are adjusted by an automatic valve. The method of claim 1, wherein the supply is interrupted by supplying a HF to a supply line immersed in the electrolyte for a period of time, and for a subsequent period of time, inert gas is forced into the In the supply line of HF, the level of the electrolyte is determined by the measured pressure difference between the level of electrolyte in the submerged line and the level of electrolyte surrounding the submerged line, followed by at least one other HF supply. And measuring the cycle of the electrolyte level. The method of claim 1, wherein the electrolytic cell is The elemental fluorine produced in (c) is intended for use in a method for fabricating an electronic device, preferably as an etchant or a chamber cleaner in a method for fabricating an electronic device. Use. The method of claim 11, wherein the electronic devices are selected from the group consisting of semiconductors, photovoltaic cells, MEMS, and TFTs. The method of claim 11, wherein the fluorine is produced "on-site" or "over the fence" of a production equipment used in the method for manufacturing an electronic device. A method for producing F ₂ in an electrolytic cell (electrolyzer) for producing elemental fluorine from a molten salt electrolyte (electrolytic) according to the first aspect of the patent application, the method comprising supplying hydrogen fluoride as a feed material to a step in the electrolytic cell (electrolyzer), the method comprising transferring hydrogen fluoride (HF) from (a) a hydrogen fluoride supply device through (b) a hydrogen fluoride supply line to (c) the electrolytic cell, wherein A full (maximum) HF feed amount supplied, a desired amount of hydrogen fluoride feed to a given fluorine production capacity (preferably gaseous HF), and a substantially lower hourly HF feed amount (kg/h) is fed to the electrolytic cell wherein the substantially lower HF feed is equal to or less than 25% of the full (maximum) feed. The method of claim 14, wherein the full (maximum) feed amount is equal to or lower than 100 kg/h, preferably equal to or lower than 80 kg/h. An electrolytic cell for producing elemental fluorine by electrolysis of a molten HF adduct of KF, wherein the electrolytic cell (c) is equipped with a connection to A hydrogen fluoride supply line (b) of the hydrogen fluoride supply unit (a), and wherein the hydrogen fluoride supply line (b) has a flow orifice having a diameter of about 2.5 mm. An electrolytic cell for producing elemental fluorine by electrolysis according to item 16 of the patent application, wherein the fluorine is in a box, preferably at the "site" or "crossing the field end" of the production equipment for the electronic device. Produced in a box for producing fluorine, preferably for use in an electronic device selected from the group consisting of semiconductors, photovoltaic cells, MEMS, and TFTs. The electrolytic cell provides a daily (24 h) production capacity of 50 to 100 kg of fluorine (F ₂ ), preferably 80 to 70, for an electrolytic cell for generating elemental fluorine by electrolysis. The daily (24 h) production capacity of 100 kg of fluorine (F ₂ ), and more preferably the daily (24 h) production capacity of about 80 to 90 kg of fluorine (F ₂ ).