KR101388817B1 - Temperature controlled cold trap for a vapour deposition process and uses thereof - Google Patents

Abstract

The present invention comprises the steps of (i) introducing a vapor phase mixture comprising at least one desired component and at least one undesired component into the condensation apparatus, and (ii) controlling the temperature in the condensation apparatus utilizing a heat transfer gas. And (iii) operating the condensation apparatus at a temperature and pressure sufficient to selectively condense at least a portion of said vapor phase mixture to obtain a recovered content containing said at least one desired component. It is about. Separation methods are useful in semiconductor applications such as recovery of unreacted organometallic compound precursors in chemical vapor deposition or atomic layer deposition methods.

Chemical vapor deposition method, thin film deposition method, condensation unit, selective separation method

Description

TEMPERATURE CONTROLLED COLD TRAP FOR A VAPOUR DEPOSITION PROCESS AND USES THEREOF}

The present invention comprises the steps of (i) introducing a vapor phase mixture comprising at least one desired component and at least one undesired component into a condensation apparatus, and (ii) controlling the temperature of the condensation apparatus utilizing a heat transfer gas. And (iii) operating the condensation apparatus at a temperature and pressure sufficient to selectively condense at least a portion of said vapor phase mixture to obtain a recovered content containing said at least one desired component. It is about.

Chemical vapor deposition is used to form a film of material on a substrate such as a wafer or other surface during semiconductor manufacturing or processing. In chemical vapor deposition, chemical vapor deposition precursors, also known as chemical vapor deposition chemical compounds, decompose thermally, chemically, photochemically or by plasma activation to form a thin film having the desired composition. For example, a vapor phase chemical vapor deposition precursor is contacted with a substrate heated to a temperature above the decomposition temperature of the precursor to form a metal containing film on the substrate. Preferably the chemical vapor deposition precursor is volatile, thermally decomposable and can produce a uniform film under chemical vapor deposition conditions.

The cost of producing the thin film by chemical vapor deposition depends on the cost of the organometallic compound and the ratio of the amount of organometallic compound consumed in the deposition reactor to the amount of organometallic compound evaporated in the precursor delivery system, ie precursor utilization. Precursor utilization in conventional chemical vapor deposition can be as low as 10% or less, and the feed gas containing most of the introduced organometallic compounds can be treated substantially with the off gas. In a conventional method, the organometallic compound in the exhaust gas may be discarded even when the organometallic compound is in an unreacted state. At low precursor utilization, the production cost of the deposited film is further influenced by the price of the organometallic compound.

Organometallic compounds are expensive because they generally require several synthetic steps. For example, even if the metal itself is not expensive, the cost increases significantly if the metal is converted synthetically to an organometallic compound. Film production costs by conventional chemical vapor deposition necessarily increase due to the price of expensive organometallic compounds.

Thin films of noble metals such as ruthenium are expected to be used significantly in the future as materials for thin film electrodes to obtain high performance electrodes. Precious metals are naturally rare metals and expensive, and their organometallic compounds are quite expensive. Therefore, when the noble metal film is produced by conventional chemical vapor deposition, it can be expected that the film formation cost will further increase.

Organometallic compound precursors are used in the production of thin films. Future film formation methods may justify organometallic compound recovery based on high compound cost and low process efficiency. In areas where compound recovery can be justified, it would be advantageous to be able to inhibit the condensation of other components (eg, auxiliary reactants and by-products) while condensing certain components (eg, raw compound molecules) of the off-gas. A problem with conventional recovery methods is that it is not possible to selectively separate the multicomponent mixtures from the emissions of various thin film deposition systems.

Therefore, there is a need in the art to develop a new method of selectively recovering unreacted organometallic compounds used in chemical vapor deposition from exhaust gases to reduce the production cost of films for chemical vapor deposition of thin films using noble metals, especially ruthenium. .

SUMMARY OF THE INVENTION [

The present invention generally relates to a method for selectively separating and recovering components of a process gas using a variable temperature condenser. The condenser is about 20 ° C (293K) to about -196 ° C (77K), preferably about 20 ° C (293K) to about -100 ° C (173K), and more preferably about -30 ° C (243K) to about -100 Operating at a temperature of < RTI ID = 0.0 > 173K < / RTI > and from about 10,000 Torr to about 1 X 10 ^-6 Torr, preferably from about 1,000 Torr to about 1 X 10 ^-3 Torr, more preferably from about 10 Torr to about 0.01 Torr. One or more components are safely and effectively separated and recovered from the chamber, for example from the effluent exiting the deposition chamber. Condensation is achieved using heat transfer gases such as cold nitrogen, argon, helium, hydrogen, carbon dioxide or clean dry air. The condenser temperature is controlled by adjusting the flow rate and / or temperature of the heat transfer gas.

The present invention relates in part to (i) introducing a gaseous mixture comprising at least one desired component and at least one undesired component into a condensing apparatus, and (ii) utilizing a heat transfer gas to adjust the temperature of the condensing apparatus. Controlling, and (iii) operating the condensation apparatus at a temperature and pressure sufficient to selectively condense at least a portion of said gaseous mixture to obtain a recovered content containing said at least one desired component. It is about.

In another aspect, the present invention provides a method for preparing a raw material gas, comprising: (i) heating and evaporating the organometallic compound in a dispensing apparatus to obtain a raw material gas; (ii) introducing the raw material gas into a reactor containing a substrate, wherein the raw material gas Reacting on the surface of the metal to produce a thin film containing metal, such as a metal or metal compound, such as oxides, nitrides, carbides, etc., (iii) removing effluent gas from the reactor, the effluent gas comprising unreacted raw material gas, (iv) introducing the effluent gas into the condensation unit, (v) controlling the temperature of the condensation unit using a heat transfer gas, and (vi) selectively condensing at least a portion of the unreacted raw material gas to Operating the condensation apparatus at a temperature and pressure sufficient to obtain a recovery content containing the reactive organometallic compound. It is about.

Further, the present invention relates in part to (i) a dispensing apparatus for heating and evaporating an organometallic compound to obtain a raw material gas, and (ii) reacting the raw material gas on the surface of the substrate to produce a metal-containing thin film, for example a metal or metal compound. A reactor containing a substrate, for example to obtain oxides, nitrides, carbides, and the like, and (iii) a variable temperature condensation device for selectively condensing at least a portion of the effluent gas, including unreacted raw material gas, from the reactor. A device for forming a thin film.

1 shows an exemplary process flow and corresponding mass balance associated with the present invention. This mass balance describes the flow and composition of the process gas at different stages throughout the thin film deposition system.

2 is a schematic of the variable temperature condenser used in Example 2 below.

3 shows the history of condenser temperature and nitrogen flow in Example 2 below.

4 shows vapor pressure data of ammonia and 1-ethyl-1′-methylruthenocene in Example 1 below.

As indicated above, the present invention uses a variable temperature condenser. Variable temperature condensers have the ability to control the heat removal rate and production temperature of the condenser. The variable temperature condenser first utilizes a heat transfer gas that is cooled by a low temperature heat sink (eg liquid nitrogen) and then sent to the condenser. The rate of heat removal from the condenser and its corresponding temperature is controlled primarily by the temperature of the heat sink and the flow of heat transfer gas. Variable temperature condensers can be used to separate the gas mixture. By controlling the temperature of the condenser, it is possible to condense the desired components of the mixture without condensing the unwanted components.

In order to achieve selective separation of the desired components from the undesired components in the gas mixture, the variable temperature condenser is approximately room temperature or from 20 ° C. (293K) to about −196 degrees (77K), preferably approximately room temperature to 20 ° C. (293K). ) To about -100 ° C (173K), more preferably about -30 ° C (243K) to about -100 ° C (173K). The variable temperature condenser is also operated at a pressure of about 10,000 Torr to about 1 × 10 ⁻⁶ Torr, preferably about 1,000 Torr to about 1 × 10 ⁻³ Torr, more preferably about 10 Torr to about 0.01 Torr.

The ability to selectively condense components from the process gas has important implications including purification and safety. Control of the condenser temperature can be used to increase the concentration of the desired component in the condensation phase. Preventing condensation of unwanted components also increases the capacity of the batch condenser. In addition, certain components (eg, ammonia and oxygen) may generate high pressure in the condenser when returning to room temperature (eg, dormant state, replacement upon reaching capacity, unintended heat loss). The low pressure (about 1 Torr) of the thin film deposition method generally requires a low condenser temperature (-100 ° C. to −30 ° C.) to condense the organometallic precursor efficiently (more than 99%). Unfortunately, the use of fixed temperature condensers can condense unwanted components. This may lead to accidental worker exposure if the device pressure limit is exceeded in the absence of heat removal.

Using gas as the heat transfer medium is a cleaner and safer alternative to using liquids, such as using closed loop glycol / water circulators. Residual fluid in cold fingers is undesirable for the recovery of air sensitive precursors that require pulling out of an inert atmosphere, such as a glove box.

Precursor recovery is a recent technology. Conventional practices and inventions have discussed the use of cold traps carried out at fixed temperatures (eg, cooling baths and liquid nitrogen). The variable temperature condenser can reach the desired temperature faster than the cooling bath due to the lower heat capacity of the gas compared to the liquid. Using nitrogen as the heat transfer gas has the additional benefit of inhibiting frost buildup and possible plugging of the cold finger inlet ducts.

The present invention provides flexibility in terms of the use of various precursors and auxiliary reactants. For example, when using a fixed temperature condenser operating at a temperature of −196 ° C. (eg liquid nitrogen), in some circumstances the precursor cannot be safely separated from the mixture containing ammonia or oxygen. On the other hand, when using a coolant trap (eg ice bath), the temperature may not be low enough to condense the desired component (eg precursor). The thermal gradient across the cold fingers (non-uniformity) is small compared to cooling baths or liquid nitrogen baths due to increased convective heat transfer when using variable temperature condensers.

An advantage of the present invention is the increased flexibility of precursor recovery apparatus over the prior art (fixed temperature condenser). Increased flexibility allows the separation of various types of mixtures by a single design.

As a general example, consider that precursor A is a component of the process gas and combines with carrier gas B and auxiliary reactant C to form the process gas. In addition, at least one by-product (D) is produced as a result of the film formation method. The mixtures (A, B, C and D) exit the film forming reactor and pass through a condenser. If so, it is necessary to know the flow rate of each component, (2) the pressure in the condenser, (3) the temperature of the condenser and (4) the vapor pressure curve of each component to determine which components will condense.

In one embodiment, the present invention provides a purification step of selectively recovering an organometallic compound component from an off-gas which is typically disposed of and optionally purifying the recovered organometallic compound to remove by-products formed in the film formation step by deposition. Deposition method for forming a thin film comprising a. According to this method, the organometallic compound is recycled. As a recovery technique, the present invention uses the technique of cooling the exhaust gas and recovering it as recovered contents. Any purification technique is to distill the recovered contents. This deposition thin film process utilizes a variable temperature condenser as described herein to selectively recover organometallic compounds.

One embodiment of the invention includes positioning a variable temperature condenser downstream of the thin film deposition system. As the exhaust gas mixture flows through the variable temperature condenser, the temperature of the inner surface of the variable temperature condenser will indicate which components are condensed and which are passed through. In the absence of experimental data, vapor pressure data can be used to determine the optimum temperature that maximizes both retention and separation selectivity of the desired component (% condensed desired component /% condensed undesired component). The final goal of condensing the unused precursor from the exhaust gas mixture is to reuse it as raw material for thin film deposition. Prior to reuse of the precursor, it should preferably be purified to remove impurities introduced by the process. Subsequent purification costs can be minimized by using a variable temperature condenser as the first step in the purification process.

Purification of the recovered organometallic compound is optional. In the purification step, since reaction by-products (decomposition products) formed through the reaction of the raw gas are introduced into the exhaust gas in the film formation step by deposition, the reaction by-products can be separated and removed from the recovered organometallic compound component.

One embodiment of the present invention provides an evaporation step of heating and evaporating an organometallic compound to produce a source gas, introducing the source gas onto the substrate and reacting the source gas on the surface of the substrate to produce a metal-containing thin film, such as a metal or metal A thin film forming step for producing a compound such as an oxide, nitride, carbide, and the like, and the exhaust gas containing the reaction product and the unreacted raw material gas formed in the thin film forming step is cooled to condense or solidify the unreacted raw material gas to form a liquid or solid organic compound. A deposition method for forming a thin film comprising a recovery step of producing recovery contents containing a metal compound. Optionally, the method includes a purification step of separating and purifying the organometallic compound from the recovered contents.

Since organometallic compounds generally exhibit low melting and boiling points, phase changes can occur at relatively low temperatures. According to the present invention, the exhaust gas is cooled to induce a phase change of the organometallic compound from the gas phase to the solid state or the liquid state to recover the organometallic compound. The recovered organometallic compound is optionally further purified to produce a high purity organometallic compound. The present invention can recover the component containing the unreacted organometallic compound, and can extract the organometallic compound in a state that can be recycled. Therefore, the present invention can reduce the production cost of the thin film through the organometallic compound to be recycled, even when the use efficiency of the material is low.

In one embodiment, the present invention provides (i) providing a vapor phase reactant distribution device, (ii) adding a reactant comprising an organometallic compound and liquid or solid at room temperature to the vapor phase reactant distribution device, and (iii) Heating the reactants in the vapor phase reactant distribution device to a temperature sufficient to evaporate the reactants to provide vapor phase reactants, (iv) supply a carrier gas to the vapor phase reactant distribution device, and (v) vapor phase reactants and transport Evacuating gas from the vapor phase reactant distribution device through the vapor phase reactant discharge line, (vi) supplying vapor phase reactant and carrier gas to the deposition chamber, and (vii) heating the vapor phase reactant in the deposition chamber. (viii) drain any remaining effluent through the effluent discharge line connected to the deposition chamber, and (ix) unreacted vapor phase reaction. Effluent containing water is supplied to the condensation unit, (x) the heat transfer gas is used to control the temperature of the condensation unit, and (xi) selectively condenses at least a portion of the unreacted vapor phase reactants to unreacted organic A method of recovering an organometallic compound comprising operating the condensation apparatus at a temperature and pressure sufficient to produce a recovery content containing the metal compound.

1 describes an exemplary process flow and corresponding mass resins associated with the present invention. This mass balance describes the flow and composition of the process gas at different stages throughout the thin film deposition system. The total flow (s) entering and exiting each node is indicated by subscripts (for example, the total flow from node 1 to 2 is denoted by "F ₁₂ "). Precursor flow is indicated by the addition of the subscript “pre” (eg, precursor flow from node 2 to 3 is denoted “F _pre23 ”).

Evaporative gases (eg, nitrogen, argon and helium) are used to transfer precursor vapor from the precursor evaporator (node 3) to the delivery system (node 5). The molar fraction of precursor in the gas mixture leaving the evaporator is denoted as x _pre35 . Assuming that the mixture exiting the evaporator is saturated with the precursor, the theoretical value of x _pre35 is equal to the precursor vapor pressure divided by the total pressure. In practice, the mixture may not be fully saturated and the saturation (0-100%) may vary depending on the equipment and process conditions. Saturation can be measured and correlated as a function of process conditions. For simplicity, the saturation is assumed to be 100%.

Additional gas species, including auxiliary reactants (eg hydrogen, oxygen), are added to the process gas mixture of the delivery system. From the delivery system, process gas is sent to the reactor. The substrate in the reactor is contacted with the process gas at the desired conditions (eg, temperature and pressure) to deposit a thin film having suitable properties (eg, thickness, composition and shape). Two main pathways for precursor consumption in the reactor labeled F _pre67 are films deposited on the intended substrate and undesired film deposits on the reactor inner surface. Again undesirable, the precursor may also be consumed by gas phase reaction.

The amount of precursor consumed in the reactor (F _pre67 ) divided by the amount of precursor evaporated (F _pre23 ) is defined as precursor utilization (also called deposition efficiency). In many thin film processes, the precursor utilization is less than 100%. For processes with very low precursor utilization (eg, less than 10%), low precursor utilization may limit the use of precursors, which are preferred solutions based on technical performance. Condensing and recycling unused precursors may enable the use of more expensive precursors that produce optimal film properties.

Liquid organometallic compound precursors as described above may be atomized and sprayed onto the substrate. Particulate and spray devices such as nozzles, sprayers and the like that can be used are known in the art.

In a preferred embodiment of the invention, organometallic compounds as described above are used in vapor deposition techniques to form powders, films or coatings. The compound may be used as a single source precursor or may be used with steam generated by heating one or more other precursors, for example one or more other organometallic compounds or metal complexes. More than one organometallic compound precursor, such as those described above, may be used in certain processes.

Deposition can be performed in the presence of other gas phase components. In one embodiment of the invention, the film deposition is performed in the presence of at least one non-reactive carrier gas. Examples of non-reactive gases include inert gases such as nitrogen, argon, helium and other gases that do not react with the organometallic compound precursor under process conditions. In other embodiments, film deposition is performed in the presence of one or more reactive gases. Some reactive gases that may be used include, but are not limited to, hydrazine, oxygen, hydrogen, air, oxygen rich air, ozone (O ₃ ), nitrogen oxides (N ₂ O), water vapor, organic vapors, ammonia, and the like. As is known in the art, the presence of oxidizing gases such as air, oxygen, oxygen rich air, O ₃ , N ₂ O or vapors of oxidative organic compounds is advantageous for the formation of metal oxide films.

In one embodiment, hydrogen or other reducing gas can be used in a BEOL (post-production line) atomic layer deposition process at a temperature below 300 ° C., so that deposition can be performed in a manner compatible with the rest of the BEOL integration strategy. Exemplary atomic layer deposition strategies for forming BEOL interconnects using ruthenium are low K recovery, tantalum nitride atomic layer deposition, ruthenium atomic layer deposition and copper electrochemical deposition. Hydrogen-reducible ruthenium complexes can also be used for ruthenium integration in MIM stack cell DRAM capacitors.

The deposition methods described herein can be performed to form a film, powder or coating comprising a single metal, or a film, powder or coating comprising a single metal or metal compound such as oxides, nitrides, carbides and the like. Mixed films, powders or coatings may also be deposited, for example mixed metal oxide films. The mixed metal oxide film can be formed, for example, by using a plurality of organometallic precursors selected from at least one of the organometallic compounds described above.

Vapor phase film deposition can be performed to form a film in a desired thickness, for example in the range of about 1 nm to more than 1 mm. The precursors described herein are particularly useful for producing thin films, such as films having a thickness in the range of about 10 nm to about 100 nm. The film of the present invention can be considered in particular in the manufacture of metal electrodes, for example, as p-type metal electrodes in CMOS (complementary metal oxide semiconductor) logic, as capacitor electrodes for DRAM applications and as dielectric materials.

The method is also suitable for producing layered films in which two or more layers differ in phase or composition. Examples of layered films include metal-insulator-semiconductors, and metal-insulator-metals.

In one embodiment, the present invention relates to a method comprising the step of thermally, chemically, photochemically, or by plasma activation the vapor of the organometallic compound precursor described above to form a film on a substrate. For example, the vapor generated by the compound is contacted with a substrate having a temperature sufficient to allow the organometallic compound to decompose to form a film on the substrate.

Organometallic compound precursors may be used in chemical vapor deposition, or more specifically metalorganic chemical vapor deposition processes known in the art. For example, the organometallic compound precursors described above can be used in low pressure as well as chemical vapor deposition processes in the atmosphere. The compounds can be used for high temperature wall chemical vapor deposition, in which the entire reaction chamber is heated, and for low temperature wall or hot wall type chemical vapor deposition, in which only the substrate is heated.

The organometallic compound precursors described above can be used in a plasma or light-assisted chemical vapor deposition method, wherein energy or electromagnetic energy from the plasma is used to activate the chemical vapor deposition precursor, respectively. In addition, the compounds may be used in ion beam, electron beam assisted chemical vapor deposition processes, each of which sends an ion beam or electron beam to a substrate to supply energy for decomposing the chemical vapor deposition precursor. Laser assisted chemical vapor deposition methods can also be used that direct laser light to a substrate to affect the photolysis reaction of the chemical vapor deposition precursor.

The process of the invention can be carried out in a variety of chemical vapor deposition reactors known in the art, such as hot or cold wall reactors, plasma assisted, beam assisted or laser assisted reactors.

Examples of substrates that can be coated using the method of the invention include solid substrates such as metal substrates such as Al, Ni, Ti, Co, Pt, Ta; Metal silicides such as TiSi ₂ , CoSi ₂ , NiSi ₂ ; Semiconductor materials such as Si, SiGe, GaAs, InP, diamond, GaN, SiC; Insulators such as SiO ₂ , Si ₃ N ₄ , HfO ₂ , Ta ₂ O ₅ , Al ₂ O ₃ , barium strontium titanate (BST); Barrier materials such as TiN, TaN; Or a substrate comprising a combination of materials. In addition, films or coatings may be formed on glass, ceramics, plastics, thermoset polymeric materials and other coatings or film layers. In a preferred embodiment, film deposition is carried out on substrates used in the manufacture or processing of electronic components. In other embodiments, the substrates are used to support low resistivity conductor deposits or optically transmissive films that are stable in the presence of oxidants at high temperatures.

The method of the present invention can be performed to deposit a film on a substrate having a smooth and flat surface. In one embodiment, this method is performed to deposit a film on a substrate used in wafer fabrication or processing. For example, this method can be performed to deposit a film on a patterned substrate that includes a shape, such as a trench, hole, or via. In addition, the method of the present invention can be integrated with other steps of wafer fabrication or processing, such as masking, etching, and the like.

Chemical vapor deposition films may be deposited to a desired thickness. For example, the formed film may be less than 1 micrometer thick, preferably less than 500 nanometer thick, more preferably less than 200 nanometer thick. Membranes having a thickness of less than 50 nanometers, such as those having a thickness of about 0.1 to about 20 nanometers, may also be produced.

The organometallic compound precursors described above are also in the process of the invention, atomic layer deposition (ALD) or atomic layer nucleation, which in turn exposes the substrate to a pulse, reactive gas (eg oxidant) and inert gas stream of the precursor. It can be used to form a film by the (ALN) technique. Sequential layer deposition techniques are described, for example, in US Pat. Nos. 6,287,965 and 6,342,277. The disclosures of both patents are incorporated herein by reference in their entirety.

For example, in one ALD cycle, the substrate is exposed in a stepwise manner to a) an inert gas, b) an inert gas carrying precursor vapor, c) an inert gas, and d) an oxidant (alone or with an inert gas). Let's do it. In general, each step can be as short as the equipment allows (eg milliseconds) and as long as the process requires (eg several seconds to several minutes). The duration of the work cycle can be short milliseconds and long minutes. The cycle is repeated over a period that may range from minutes to hours. The resulting film can be as thin as a few nanometers or thicker, for example 1 millimeter (mm).

The precursor decomposes to form a metal containing film on the substrate. The reaction also produces organic materials from the precursors. The organic material is dissolved by the solvent fluid and easily removed from the substrate. It is also possible to form a metal oxide film by using an oxidizing gas, for example.

As an example, the decomposition process is performed in a reaction chamber containing one or more substrates. The entire chamber is heated to the desired temperature, for example by using a furnace to heat it. Vapors of organometallic compounds can be produced, for example, by applying a vacuum to the chamber. For low boiling compounds, the chamber may be hot enough to cause evaporation of the compound. The vapor decomposes in contact with the surface of the heated substrate and forms a metal containing film such as a metal or metal compound such as oxides, nitrides, carbides and the like. As described above, the organometallic compound precursor may be used alone or in combination with one or more components, such as other organometallic precursors, inert carrier gases or reactive gases.

In a system that can be used in film formation by the method of the present invention, the raw material can be sent to a gas-blending manifold to produce a process gas that is fed to a deposition reactor in which film growth is performed. Raw materials include, but are not limited to, carrier gases, reactive gases, purging gases, precursors, etching / cleaning gases, and the like. Accurate control of the process gas composition is achieved using mass flow regulators, valves, pressure transducers, and other devices known in the art. The exhaust manifold can carry the gas exiting the deposition reactor as well as the bypass stream to a vacuum pump. A removal system downstream of the vacuum pump can be used to remove any toxic material from the exhaust gas. The deposition system may be equipped with an in-situ analysis system that includes a residual gas analyzer that enables measurement of process gas composition. Control and data collection systems can monitor various process parameters (eg, temperature, pressure flow rate, etc.).

The organometallic compound precursors described above can be used to produce a film comprising a single metal, or a film comprising a single metal oxide, nitride, carbide, and the like. It is also possible to deposit mixed films, for example mixed metal containing films. Such films are produced using, for example, various organometallic precursors. The metal film may be formed, for example, without the use of a carrier gas, steam or other oxygen source.

Membranes formed by the methods described herein are methods known in the art, such as X-ray diffraction, Auger spectroscopy, X-ray photoelectron emission spectroscopy, nuclear spectroscopy, scanning electron microscopy and other known in the art. It can be characterized by technology. The resistivity and thermal stability of the membrane can be measured by methods known in the art.

Referring again to FIG. 1, precursors not consumed for film formation exit to the reactor effluent. The composition of the process gas exiting the reactor is calculated based on the precursor utilization. Condensers downstream of the reactor can be used to remove components from the vapor phase. The temperature of the condenser will be affected by the composition of the condensate phase. In precursor recovery, the goal is to maximize the condensation of the precursor and minimize the condensation of other species. When the precursor reaches saturation in the gas phase of the condenser, the theoretical mole fraction (x _pre810 ) of the precursor exiting the condenser can be calculated by dividing the precursor vapor pressure by the total pressure. Similar to the prior discussion regarding precursor evaporators, in fact the saturation of the condenser is not 100%. The condenser temperature should be controlled to maintain the maximum amount of precursor and optimize the selectivity of precursor condensation over other species of condensation. Condenser efficiency is defined as the amount of precursor condensed in the condenser divided by the amount of precursor introduced into the condenser.

The conditions for cooling the exhaust gas in the recovery stage are determined by the nature of the organometallic compound used. Particular mechanisms for cooling the exhaust gas in the recovery step and for recovering the organometallic compound include, for example, arrangements for mounting the variable temperature condenser in the piping from the reactor chamber.

If the condenser approaches its capacity, the condensed material must be removed. The precursor is then separated from the condensed material and returned to the precursor reservoir for use in the film formation process. Any uncondensed precursor proceeds to the removal system and is discarded in an appropriate manner.

The recovered contents recovered in the recovery step may consist essentially of unreacted organometallic compounds and reaction products. Such reaction products may include water, carbon dioxide, aldehydes, formic acid, oxides or hydroxides of compounds, and other low molecular weight compounds. Metal atoms are removed from the organometallic compound by a reaction for forming a thin film, and the organometallic compound is decomposed to produce such a low molecular weight compound. These water and other reaction products are impurities, but they can be easily separated and removed in the purification step because they have very different physical properties than those of the target organometallic compound to be purified.

Therefore, it is preferable to separate the organometallic compound by distillation of the contents recovered in the purification step. Organometallic compounds with good purity can be separated directly by distillation because organometallic compounds generally have low melting and boiling points and can lead to phase inversion at relatively low temperatures as described above. In addition, distillation does not require complicated equipment and is a relatively easy purification technique.

The organometallic compound for use in the present invention is not particularly limited. Organic compounds of various metals such as ruthenium, platinum, palladium, copper, indium, lanthanum, tantalum, tungsten, molybdenum, lanthanide elements, zirconium, niobium, aluminum, titanium, and rhenium can be used as materials for thin film formation. . Some of these metals are inexpensive as the metals themselves, but their organometallic compounds are quite expensive. Therefore, it is possible to reduce costs in forming thin films of these metals or metal oxides, nitrides, carbides and the like.

In addition, the present invention, in view of the recent increase in demand for thin films of noble metals and the high price of organic compounds of noble metals, has been applied to the preparation of thin films using noble metals such as organometallic compounds of platinum, palladium, ruthenium, rhodium, iridium or osmium. Especially useful.

Finally, the chemical vapor deposition apparatus for thin film production to which the variable temperature condenser apparatus is applied will be illustrated. Chemical vapor deposition methods for thin film formation are carried out using any of the purification steps added to the variable temperature condenser apparatus and conventional chemical vapor deposition apparatus for thin film production without significant change in their arrangement. Specifically, the chemical vapor deposition apparatus for thin film generation according to the present invention is a chemical vapor deposition apparatus for thin film generation comprising a solution containing an organometallic compound as a material, a heating device for heating the solution to evaporate the organometallic compound to obtain a source gas And a reactor for reacting the source gas to form a metal-containing thin film such as a metal or a metal compound such as an oxide, nitride, carbide, or the like on a substrate. The apparatus comprises a variable temperature condenser for obtaining the recovered contents containing the organometallic compound from an off gas consisting of the reaction product and the unreacted raw material gas formed via the reaction downstream from the reactor, and optionally from the recovered contents And a purification device for separating and purifying the compound.

Other embodiments of the present invention, including apparatus, include the following: For processes operated at subatmospheric pressure (thin film deposition is typically carried out at or below atmospheric pressure), the condenser must be properly designed (eg Vacuum compatibility); The condenser must have a metal seal to minimize the permeation of atmospheric components (eg water and oxygen) and the possibility of subsequent reactions; Condensers must be designed and operated for high condensation efficiency (which can be achieved through various techniques, including maximizing surface area and residence time); The temperature of the condenser is monitored using a sensor (eg thermocouple); The temperature signal is used to adjust the heat transfer gas (eg nitrogen) to control the rate of heat removal.

Those skilled in the art will recognize that various changes may be made to the methods described herein in detail without departing from the scope and spirit of the invention as more specifically defined in the following claims. For example, the present invention can be applied to applications other than thin film deposition (eg, for separation techniques or analytical purposes common in the chemical or pharmaceutical industry); Multiple variable temperature condenser devices can be used to separate mixtures of multiple compounds; The condenser can be equipped with a valve to periodically drain the liquid; Multiple sensors can be used to measure the condenser temperature profile; A heater may be installed in the heat transfer fluid line to heat the trap; Metal gasket seals may be used on the condenser; A sensor (thermocouple) can be installed in the liquid nitrogen dewar to indicate when it needs to be recharged; This may indicate when the sensor is installed in the condenser and reaches its capacity. Flow alarm signals indicative of an unacceptable flow of heat transfer gas (eg, no flow) can be used to alert the driver or to trigger an event automatically.

For organometallic compounds recovered by the process of the invention, through recrystallization, more preferably through extraction and chromatography of the reaction residue (eg hexane), most preferably through sublimation and distillation. Any purification can be carried out.

Examples of techniques that can be used to characterize recovered organometallic compounds include, but are not limited to, analytical gas chromatography, nuclear magnetic resonance, thermogravimetric analysis, inductively coupled plasma mass spectroscopy, differential scanning calorimetry, vapor pressure, and viscosity measurements. .

The relative vapor pressure, or relative volatility, of the organometallic compound precursors described above can be measured by thermogravimetric analysis techniques known in the art. In addition, the equilibrium vapor pressure can be measured, for example, after degassing all gas from the sealed vessel, introducing the vapor of the compound into the vessel, and the pressure as known in the art.

In addition, within the scope of the present invention, the temperature of the heat transfer gas can be reduced using methods other than liquid nitrogen. Alternative heat sink media include, for example, liquids and solids such as cryogenic liquids (eg, argon and helium) and solid carbon dioxide that are maintained at temperatures below -50 ° C.

In another embodiment, the present invention relates to the use of multiple variable temperature condensers in series. Using multiple variable temperature condensers in series provides the ability to selectively condense multiple components. Depending on the particular application, the contents recovered from each of the variable temperature condensers arranged in series can be regarded as reusable material or waste material.

In a further embodiment of the invention, the recovered contents can be conveyed directly (eg, pumped) back to the input of the process (eg recycle).

In addition to the other fields described herein, variable temperature condensers can be used for synthesis and analysis purposes.

As used herein, condensation refers to a change from a gaseous or vapor state to a liquid or solid state. Condensation may also include changing from a liquid state to a solid state.

Various modifications and variations of the present invention will be apparent to those skilled in the art, and such modifications and variations are to be understood as being included within the spirit and scope of the present application and claims.

Example  One

1-ethyl-1'-methylruthenocene and ammonia were used for the deposition of ruthenium films by the plasma enhanced atomic layer deposition (PEALD) method. In this method, the substrate was exposed using a four step cycle. The process gas composition during each step is described in the table below.

step Process gas composition One 1-ethyl-1'-methylruthenocene / argon 2 Argon fuzzing 3 Ammonia / Argon Plasma 4 Argon fuzzing

The general range of conditions for the PEALD process using 1-ethyl-1'-methylruthenocene and ammonia is described in the table below.

Duration of each step (seconds) 0.1 to 10000 Reactor Pressure (Torr) 0.001 to 1000 Substrate Temperature (℃) 25 to 600 Total process gas flow, standard cubic centimeters per minute 1 to 10000 Molar fraction of 1-ethyl-1'-methylruthenocene in the off-gas 0 to 1 Molar fraction of ammonia in the off-gas 0 to 1

Vapor pressure data for 1-ethyl-1′-methylruthenocene and ammonia are shown in FIG. 4.

The vapor pressures of these two materials can be approximated by the formula:

P _vap (Torr) = e ^{[AB / T (K)]}

Based on the data in FIG. 4, the R-squared values of the equation and the optimal values of the constants A and B are as follows.

A B R ² ammonia 21.11 -3421 0.9932 1-ethyl-1'-methylruthenocene 22.07 -8176 0.9998

In order to calculate how much of a certain component of the exhaust gas condenses, it was necessary to know the temperature and pressure of the condenser. In addition, it was necessary to know the composition of the exhaust gas introduced into the condenser, for example, the mole fraction of each component.

The goal is to condense 100% 1-ethyl-1'-methylruthenocene and 0% ammonia (none). The most efficient separation will occur when the condenser temperature is above the ammonia dew point to prevent condensation of ammonia. The dew point temperature is the temperature at which the liquid or solid is in equilibrium with the vapor phase (eg, the evaporation / sublimation rate is the same as the condensation rate). The process is also limited by the requirement to maintain a condenser temperature low enough to condense as much of 1-ethyl-1'-methylruthenocene as possible. For mixtures containing 1-ethyl-1'-methylruthenocene and ammonia, the optimum condenser temperature is slightly above the dew point of ammonia.

To illustrate the utilization of a variable temperature condenser, consider the following examples. The total pressure in the condenser is 1 Torr. In a pulsed process (eg ALD or PEALD), the mole fraction of the components (eg ammonia and 1-ethyl-1'-methylruthenocene) in the off-gas mixture entering the condenser will vary over time . The maximum partial pressure of ammonia or 1-ethyl-1'-methylruthenocene is 1 Torr. At a partial pressure of 1 Torr, the dew point temperature of 1-ethyl-1'-methylruthenocene is approximately 100 ° C. In the absence of mass transfer resistance, the temperature required to reduce the partial pressure of 1-ethyl-1'-methylruthenocene to the desired value can be calculated. For example, reducing the partial pressure of 1-ethyl-1'-methylruthenocene to 99.999% (eg, from 1 Torr to 0.00001 Torr) would require a condenser temperature of -30 ° C. Due to the presence of mass transfer limitations in practical applications, it is desirable to operate at the lowest possible condenser temperature. The dew point temperature of ammonia at a pressure of 1 Torr is -116 ° C. As a result, the condenser will be operated at a temperature slightly above -116 ° C. to prevent condensation of ammonia but to condense as much of 1-ethyl-1'-methylruthenocene as possible.

Changes in process conditions will affect the optimum condenser temperature. Specifically, increasing the partial pressure of ammonia (e.g., increasing the total pressure at a fixed composition) requires increasing the condenser temperature to prevent condensation of the ammonia. In addition, the use of auxiliary reactants other than ammonia and / or the presence of reaction byproducts will also affect the lowest allowable condenser temperature. Variable temperature condensers can easily adapt to this type of process change compared to fixed temperature devices (eg liquid nitrogen).

Two advantages are obtained by using dry inert gas (eg nitrogen) as the heat transfer medium. First, the thermal mass of the system is reduced compared to the liquid heat transfer fluid. This reduces the time it takes to change the temperature of the condenser (eg, cool the condenser to process temperature or return the condenser to room temperature). The second advantage relates to the condenser operation in the glove box, which may be necessary to remove the condensed precursor (assuming the precursor is air-sensitive). The use of dry inert gas (eg nitrogen) as the heat transfer fluid prevents the condenser from being exposed to water and / or other heat transfer liquids, which is undesirable for subsequent use in the glove box.

Example  2

A nitrogen standard for the coils immersed in a dewar (2 liter capacity) filled with liquid nitrogen was used using a 20 standard liters per minute (slpm) mass flow controller supplied by MKS Instruments. Nitrogen heat transfer gas was then sent to the cold finger of the process gas condenser (KDFT4150-2LN, 4 inch body diameter, 1.5 inch inlet and outlet tube diameters commercially available from MDC Vacuum Products). Nitrogen heat transfer gas was delivered using a 1/4 inch stainless steel tube with a wall thickness of 0.035 inches. The flow of nitrogen heat transfer gas to the cold finger was adjusted using the condenser temperature as the feedback signal. Cold finger temperature was monitored using a Type A thermocouple (1/8 inch diameter, 12 inch long stainless steel sheath). 2 shows the device used. 3 shows the history of condenser temperature and nitrogen flow. Temperatures below -100 ° C. (173 K) were achievable and the present example shows that the condenser temperature can be automatically controlled using a feedback arrangement. The set temperature was reduced from 25 ° C. to −125 ° C. in steps of 25 ° C. every 10 minutes. At maximum flow (20 standard liters per minute), the condenser temperature could be reduced by approximately 30 ° C / min.

Example  3

The ability to operate and control the condenser at temperatures below 100 ° C. (173 K) was evaluated in the apparatus shown in FIG. 2. Using nitrogen as the heat transfer gas, a flow of about 10 standard liters per minute was fed through a coil immersed in a dewar of liquid nitrogen. The heat transfer gas was then discharged onto the cold fingers (condenser) of the stainless steel liquid nitrogen trap to bring the temperature of the cold fingers below −100 ° C. (173 K). In addition, the temperature of the cold finger can be controlled to a value between -100 ° C (173K) and room temperature using a signal from the condenser thermocouple of the feedback circuit to control the flow of nitrogen through the coil and thus the rate of heat removal. Could.

Claims (14)

(i) introducing a vapor phase mixture comprising at least one desired component and at least one undesired component into a variable temperature condenser; (ii) controlling the temperature of the variable temperature condenser to a temperature of 20 ° C. (293K) to −196 ° C. (77K) utilizing a heat transfer gas cooled by a heat-sink; (iii) controlling the rate of heat removal from the variable temperature condenser by controlling the temperature of the heat sink and the flow rate of heat transfer gas from the heat sink to the variable temperature condenser; (iv) controlling the pressure of the variable temperature condenser to a pressure of 10,000 Torr to 1 × 10 ⁻⁶ Torr; And (v) operating a variable temperature condenser to selectively condense at least a portion of said vapor phase mixture to obtain a recovered content containing said at least one desired component, Wherein said variable temperature condenser is a single condensation chamber in which total condensation is performed. The method of claim 1 wherein said at least one desired component comprises an organometallic compound. The compound according to claim 2, wherein the organometallic compound is a ruthenium-containing compound, a platinum-containing compound, a hafnium-containing compound, a tantalum-containing compound, a molybdenum-containing compound, a tungsten-containing compound, a titanium-containing compound, a lanthanum-containing compound , Palladium-containing compounds, aluminum-containing compounds, copper-containing compounds, zirconium-containing compounds, niobium-containing compounds, iridium-containing compounds, cadmium-containing compounds, bismuth-containing compounds, strontium-containing compounds, silicon-containing compounds Or a lanthanide element-containing compound. The method of claim 1, wherein the heat transfer gas comprises nitrogen, argon, helium, hydrogen, carbon dioxide, or clean dry air. delete (i) heating and evaporating the organometallic compound in a dispensing apparatus to obtain a source gas; (ii) introducing the raw material gas into a reactor containing a substrate and allowing the raw material gas to react on the surface of the substrate to produce a metal-containing thin film; (iii) removing the effluent gas from the reactor, including unreacted crude gas; (iv) introducing effluent gas into the variable temperature condenser; (v) controlling the temperature of the variable temperature condenser to a temperature of 20 ° C. (293K) to −196 ° C. (77K) utilizing a heat transfer gas cooled by a heat sink; (vi) controlling the rate of heat removal from the variable temperature condenser by controlling the temperature of the heat sink and the flow rate of heat transfer gas from the heat sink to the variable temperature condenser; (vii) controlling the pressure of the variable temperature condenser to a pressure of 10,000 Torr to 1 × 10 ⁻⁶ Torr; And (viii) operating a variable temperature condenser to selectively condense at least a portion of the unreacted raw material gas to obtain a recovered content containing unreacted organometallic compound, The variable temperature condenser is a method for the selective recovery of the organometallic compound is a single condensation chamber in which the entire condensation is performed The compound according to claim 6, wherein the organometallic compound is a ruthenium-containing compound, a platinum-containing compound, a hafnium-containing compound, a tantalum-containing compound, a molybdenum-containing compound, a tungsten-containing compound, a titanium-containing compound, a lanthanum-containing compound , Palladium-containing compounds, aluminum-containing compounds, copper-containing compounds, zirconium-containing compounds, niobium-containing compounds, iridium-containing compounds, cadmium-containing compounds, bismuth-containing compounds, strontium-containing compounds, silicon-containing compounds Compound, or a lanthanide element-containing compound. The method of claim 6 wherein the heat transfer gas comprises nitrogen, argon, helium, hydrogen, carbon dioxide or clean dry air. delete The method of claim 6, wherein the substrate is comprised of a material selected from the group consisting of metals, metal silicides, semiconductors, insulators, and barrier materials. The method of claim 6, wherein the substrate is a patterned wafer. The method of claim 6, wherein the reactor is a deposition chamber selected from a chemical deposition chamber or an atomic layer deposition chamber. (i) a distribution device for heating and evaporating the organometallic compound to obtain a source gas, (ii) a reactor containing the substrate for reacting the source gas on the surface of the substrate to obtain a metal-containing thin film, and (iii) unreacted And a variable temperature condensation device for selectively condensing at least a portion of the effluent gas comprising the source gas from the reactor. The apparatus of claim 13, wherein the reactor is a deposition chamber selected from a chemical deposition chamber or an atomic layer deposition chamber.

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