Exhaust gas abatement system and method

Abstract

The present invention provides an exhaust gas abatement system for use in semiconductor processing. The system includes a vacuum pump having an exhaust outlet, a water eductor coupled to the exhaust outlet of the vacuum pump, and a separator coupled to the water eductor. The system further includes an exhaust gas abatement device coupled to the gaseous exhaust outlet of the separator. The system is configured, in use, such that an exhaust stream from the exhaust outlet of the vacuum pump is conveyed through the water eductor to the separator, and the separator is configured, in use, to separate gaseous components of the exhaust stream from non-gaseous components of the exhaust stream.

Description

[Technical Field]

[0001] The present invention relates to an exhaust gas abatement system for use in semiconductor processing, a method for abating exhaust gases from a semiconductor processing chamber, and the use of a water eductor and separator in an exhaust gas abatement system for semiconductor manufacturing. [Background technology]

[0002] Semiconductor products are made by processing single crystal silicon wafers through multiple lithography, deposition, and etching steps. Various precursor chemical vapors are used to perform these steps, which are typically performed under high vacuum. Typically, the efficiency of using these chemical vapors in the fabrication of semiconductor devices is fairly low. It has been estimated that in some cases, more than 50% of the precursor chemical vapors exit the semiconductor processing chamber through an outlet connected to a vacuum pump (i.e., the vacuum foreline). The precursor chemical vapors can then be transported through the vacuum pump in the form of an exhaust stream.

[0003] As the exhaust stream exits the vacuum pump's exhaust, it is typically diluted with nitrogen gas to reduce the likelihood of chemical vapor condensation. The nitrogen gas also helps reduce the flammability of the resulting mixture, thereby improving safety. In addition, the pump's exhaust line is typically heated to reduce the likelihood of condensation of volatile chemical vapors. The nitrogen-diluted chemical vapor mixture is conveyed to an abatement system where it is destroyed using high temperatures generated by either combustion (e.g., of methane gas) or electrical arcing.

[0004] The vacuum pump exhaust line is typically about 15 feet (4.572 meters) to about 40 feet (12.192 meters) in length. The vacuum pump exhaust line connects the vacuum pump to the abatement system.

[0005] The presence of precursor chemical vapors in the exhaust line of a vacuum pump can cause many different problems depending on the chemical vapor and its condition.

[0006] As an example, titanium tetrachloride is used in the chemical vapor deposition of titanium nitride thin films when reacted with ammonia gas. Titanium tetrachloride is a liquid at room temperature and is highly reactive with water. When titanium tetrachloride is used in semiconductor processing, the exhaust composition of a vacuum pump may contain unreacted titanium tetrachloride and ammonia gas in nitrogen. Any "cold spots" along the exhaust line may cause titanium tetrachloride to condense. This can lead to a dangerous condition due to the accumulation of liquid chemicals that can undergo subsequent reactions and cause localized corrosion in the pump's exhaust line. This is particularly dangerous when water condensation is present during either semiconductor processing or routine maintenance.

[0007] Tungsten hexafluoride, which has a boiling point of 17°C, reacts with water and is widely used in semiconductor processing. Diluting the vacuum pump exhaust stream containing tungsten hexafluoride with nitrogen and heating the vacuum pump exhaust line are important for safe and continuous operation.

[0008] Ammonium nitrate is a product of various chemical vapor reactions that can occur within semiconductor processing chambers or along vacuum forelines. Ammonium nitrate has a melting point of 169.6°C and a boiling point of 210°C. If the pump exhaust line is not heated to at least 250°C, ammonium nitrate may condense and deposit. The accumulation of ammonium nitrate in the vacuum pump exhaust line can create localized deposits that can explode upon reaction with the pump exhaust gases or due to friction / vibration of the exhaust line, for example during a maintenance schedule.

[0009] Advanced semiconductor processing by atomic layer deposition (ALD) typically uses vapors of chemical precursors such as trimethylaluminum (TMA). Trimethylaluminum has a boiling point of approximately 125°C to 130°C and is highly reactive with water. The atomic layer deposition process requires that the exhaust line of the vacuum pump be uniformly heated to at least 200°C along its length. Any cold spots in the vacuum exhaust line can result in condensation of trimethylaluminum, requiring removal through highly dangerous and costly maintenance procedures. Condensation of trimethylaluminum at the inlet of exhaust gas abatement systems has been well documented. This can therefore require frequent maintenance under potentially dangerous conditions.

[0010] Other thin film processes may use tetrakis(dimethylamido)titanium precursors. The use of these precursors can result in exhaust gas streams that can lead to significant particle deposition in the exhaust lines of vacuum pumps. This can clog the inlet nozzles of abatement systems, resulting in frequent breakdowns and high production costs.

[0011] It is therefore desirable to provide an improved exhaust gas abatement system to reduce the deposition of chemical precursors, thereby reducing the frequency of required maintenance and the associated risks. Summary of the Invention [Problem to be solved by the invention]

[0012] The present invention is directed to at least partially overcoming these and other problems associated with the prior art. The embodiments described in more detail below are directed to providing an improved exhaust gas abatement system for use in semiconductor processing. [Means for solving the problem]

[0013] The invention is defined in the following set of claims.

[0014] In a first aspect, the present invention provides an exhaust gas abatement system for use in semiconductor processing. The system comprises a vacuum pump having an exhaust outlet and a water eductor coupled to the exhaust outlet of the vacuum pump. The system further comprises a separator coupled to the water eductor. The system further comprises an exhaust gas abatement apparatus, preferably an abatement furnace, coupled to the gaseous exhaust outlet of the separator. The system is configured, in use, such that an exhaust stream from the exhaust outlet of the vacuum pump is conveyed to the separator via the water eductor. The separator, in use, is configured to separate gaseous components of the exhaust stream from non-gaseous components of the exhaust stream.

[0015] For purposes of this invention, semiconductor processing can include processing of silicon wafers by one or more lithography, deposition, and etching steps. Semiconductor processing can include, for example, one or more physical vapor deposition, chemical vapor deposition, electrochemical deposition, epitaxial growth, and / or atomic layer deposition steps.

[0016] The exhaust stream from the semiconductor processing step(s) may contain precursor chemical vapor(s). Typically, the exhaust stream can be diluted with nitrogen gas. Preferably, the exhaust gas can be diluted with nitrogen gas at the exhaust port of the vacuum pump. Advantageously, this can reduce the risk of condensation of the precursor chemical vapor and can reduce the flammability of the exhaust stream. Nitrogen gas can be introduced into the exhaust stream at a flow rate of about 20 slm to about 150 slm.

[0017] In use, the vacuum pump can be configured to evacuate a chamber in which semiconductor processing occurs. In use, the vacuum pump can be connected to an exhaust outlet of the semiconductor processing chamber. An exhaust stream from the semiconductor processing chamber is conveyed through the vacuum pump and exits through the exhaust outlet of the vacuum pump. The exhaust stream can be primarily gaseous, but may also include non-gaseous materials (e.g., solid and / or liquid components). During operation, the pressure at the pump outlet is typically about 1 atmosphere.

[0018] Those skilled in the art will appreciate that the present invention can be applied to various types of vacuum pumps, and that an appropriate vacuum pump can be selected depending on the requirements of a particular application. The vacuum pump can be, for example, a turbomolecular pump and / or a multi-stage Roots pump. By way of example, the vacuum pump can be an Edwards iGX dry pump.

[0019] Preferably, the water eductor can be located at or adjacent to the exhaust outlet of the vacuum pump. The water eductor can mix the exhaust stream containing any chemical precursors with water. This mixing can be facilitated by a relatively high flow rate of water injected into the water eductor. Water-reactive chemicals in the exhaust stream can react with and / or dissolve in the water in the water eductor and, as a result, be removed from the gaseous components of the exhaust stream.

[0020] Additionally or alternatively, the water eductor can remove solid components from the exhaust stream. For example, solid deposits and / or aerosol particles formed at the exhaust outlet of the vacuum pump can dissolve upon mixing with water in the water eductor. Advantageously, positioning the water eductor adjacent to the exhaust outlet of the vacuum pump can reduce the likelihood of chemical vapors condensing in the vacuum pump exhaust line prior to the water eductor.

[0021] The separator may preferably be located at or adjacent to the outlet of the water eductor. Preferably, the inlet of the separator is directly connected to the outlet of the water eductor. The exhaust stream from the water eductor may flow directly into the inlet of the separator. Advantageously, conveying the exhaust stream through the separator may enable separation of gaseous components of the exhaust stream from non-gaseous components of the exhaust stream.

[0022] The exhaust gas abatement device can be configured to treat gaseous components of the exhaust stream from the separator. This treatment can include, for example, abatement with a gas (e.g., natural gas or methane) burner or an electric arc burner. Preferably, the exhaust gas abatement device is an abatement furnace. For example, the exhaust gas abatement device can include an internal combustion combustor, a plasma chamber, and / or an electric arc discharge chamber. By way of example, the exhaust gas abatement device can be an Atlas™ manufactured by Edwards Corporation.

[0023] The exhaust gas abatement device can be coupled to the gaseous exhaust outlet of the separator. Typically, the exhaust gas abatement device can be coupled to the gaseous exhaust outlet of the separator via an exhaust line. The exhaust line can be heated to a temperature of at least 100°C, preferably at least 200°C.

[0024] In a typical prior art system, the exhaust outlet of the vacuum pump is fluidly connected to an exhaust gas abatement system via the vacuum pump exhaust line. The vacuum pump exhaust line can be up to approximately 40 feet (i.e., 12.192 meters) long. It has been found that condensation of precursor chemical vapors is common in prior art systems, particularly in the vacuum pump exhaust line. However, in the present invention, water-reactive precursor chemical vapors can be removed from the exhaust stream by channeling the exhaust stream through a water eductor and separator between the vacuum pump exhaust outlet and the abatement system. Thus, the likelihood of precursor chemical vapor condensation in the exhaust line can be reduced.

[0025] Advantageously, the present invention can remove water-reactive precursor chemical vapors from the exhaust stream along with solid deposits in the vacuum pump or vacuum pump exhaust line. Furthermore, inorganic acids present in the exhaust stream can also be dissolved in the water jet. This can reduce the formation of deposits in the vacuum pump exhaust line and / or exhaust gas abatement system. Specifically, this can reduce the possibility of condensation of precursor chemical vapors at the vacuum pump exhaust outlet and / or exhaust gas abatement system inlet. Therefore, the frequency of maintenance can be reduced, and the safety of the system can be improved.

[0026] Typically, the water eductor may include an inlet coupled to the exhaust outlet of the vacuum pump. The water eductor may include a nozzle configured to inject water. The water eductor may further include a mixing throat. In use, the exhaust flow from the vacuum pump may mix with the injected water in the mixing throat. The water eductor may further include an expansion diffuser coupled to the mixing throat. The expansion diffuser may be defined by a chamber having a cross-sectional area that increases in a direction toward the outlet of the water eductor.

[0027] The inlet of the water eductor can be connected directly to the exhaust outlet of the vacuum pump. Alternatively, the inlet of the water eductor can be coupled to the exhaust outlet of the vacuum pump by an exhaust line (e.g., a pipe). In use, the water eductor can create a vacuum at the exhaust inlet. Advantageously, this can draw gas through the exhaust outlet of the vacuum pump and / or reduce backflow of gas through the exhaust outlet.

[0028] For purposes of this invention, water may be defined as water, distilled water, or an aqueous solution. In some embodiments, the water injected from the nozzles of the water eductor may include recycled wastewater from the acid tank of the exhaust gas abatement system and / or recycled wastewater from elsewhere in the semiconductor processing plant. The composition of the water or aqueous solution may depend on the composition of the exhaust gas stream and the particular semiconductor process occurring.

[0029] The water may be supplied to the nozzle by a pump. The pump may be part of the exhaust gas abatement system or may be a separate component. The water may provide what may be referred to as a driving fluid for the water eductor. The water eductor is typically a Venturi eductor. Typically, in use, the velocity of the water ejected from the nozzle may be greater than the velocity of the exhaust flow through the inlet of the water eductor. Advantageously, this may improve mixing of the exhaust flow with the water.

[0030] The cross-sectional area of ​​the water eductor may be reduced at the mixing throat, which may advantageously enhance mixing of the water and exhaust streams at the mixing throat.

[0031] The expansion diffuser may be directly connected to the outlet of the mixing throat. The cross-sectional area of ​​the chamber defining the expansion diffuser may increase substantially continuously in a direction toward the outlet of the water eductor. The chamber defining the expansion diffuser may have a first (e.g., proximal) cross-sectional area adjacent the mixing throat. The chamber defining the expansion diffuser may have a second (e.g., distal) cross-sectional area adjacent the outlet of the water eductor. The first cross-sectional area may be smaller than the second cross-sectional area. The cross-sectional area of ​​the chamber defining the expansion diffuser may increase substantially continuously between the first cross-sectional area and the second cross-sectional area. The chamber defining the expansion diffuser may be substantially frusto-conical.

[0032] Water can be injected through a nozzle under pressure. As the water passes through the nozzle, its velocity may increase. This results in a decrease in the water's pressure, according to Bernoulli's principle. The water then mixes with the exhaust flow from the exhaust outlet of the vacuum pump in the mixing throat, transferring kinetic energy to it. As the exhaust-water mixture exits the mixing throat and travels through the expansion diffuser, the cross-sectional area of ​​the chamber defining the expansion diffuser increases. Thus, the velocity of the exhaust-water mixture decreases and its pressure increases. This creates a pressure difference between the water eductor outlet and the exhaust inlet, which may lead to the creation of a vacuum at the water eductor inlet due to the Venturi effect.

[0033] The water eductor may comprise a valve configured to allow for controlling the flow rate of the water jet through the nozzle. Preferably, the valve is a fluid shut-off valve.

[0034] Advantageously, the water eductor can generate a vacuum at the inlet of the water eductor. For purposes of the present invention, the vacuum created by the water eductor can be defined as a relatively low pressure compared to the pressure at the exhaust outlet of the vacuum pump. The pressure at the exhaust outlet of the vacuum pump is typically about 1 atmosphere. The water eductor has no mechanically moving parts yet is capable of generating a vacuum. The generated vacuum may vary depending on the dimensions of the water eductor, selected components (e.g., nozzles, etc.), water flow rate, and water pressure. The water eductor can also advantageously enable mixing of a three-phase exhaust stream (i.e., an exhaust stream containing gas, liquid, and / or solid components). Furthermore, the water eductor provides a low-maintenance solution to problems associated with prior art systems.

[0035] Typically, the separator may include an inlet coupled to the outlet of the water eductor. The separator may further include a first chamber including a first liquid outlet and a gaseous exhaust outlet. The first chamber may be configured to be partially filled with liquid (e.g., water) in use, such that the uppermost level of the liquid defines a fill line. The first liquid outlet will typically be located below the fill line, and the gaseous exhaust outlet will typically be located above the fill line. The gaseous exhaust outlet may be connected to an exhaust gas abatement device.

[0036] Preferably, the separator may further comprise a second chamber having a liquid inlet in fluid communication with the first liquid outlet of the first chamber. The second chamber may further comprise another (i.e., second) liquid outlet. The second chamber may be positioned such that, in use, liquid passes through the second chamber in a direction substantially opposite to the direction of liquid flow through the first chamber. In use, the second chamber may be positioned below the first chamber such that any gas within the liquid is forced upward toward the gas outlet.

[0037] In use, the separator can be configured to separate gaseous components of the exhaust stream from non-gaseous components of the exhaust stream. The gaseous components of the exhaust stream can include gases that do not dissolve in water and / or any gaseous by-products of the reaction between the precursor chemical vapor and water. For example, the gaseous components can include nitrogen, oxygen, argon, ozone, nitrogen trifluoride, hydrogen, and / or methane, etc. The non-gaseous components can include water or aqueous solutions, chemicals dissolved therein, and any solid deposits carried by the water.

[0038] Typically, the separator may be a horizontal separator.

[0039] In use, the exhaust stream entering the first chamber of the separator can be directed against the inlet diverter and / or the walls of the chamber, thereby slowing the exhaust stream and allowing non-gaseous components of the exhaust stream to descend into the liquid contained within the first chamber.

[0040] In use, the flow rate of water sprayed from the nozzle of the water eductor is controlled to substantially match the flow rate of liquid discharged from the separator, and vice versa. The amount of liquid in the first chamber can be maintained such that the gaseous exhaust outlet is positioned above the fill line and the first liquid outlet is positioned below the fill line. This can increase the likelihood that gaseous components of the exhaust stream can exit the separator through the gaseous exhaust outlet and decrease the likelihood that gaseous components of the exhaust stream can exit the separator through the first liquid outlet.

[0041] Typically, the separator may further comprise a third chamber having a liquid inlet fluidly connected to the second liquid outlet and a further (i.e., third) liquid outlet. The third chamber may be arranged such that liquid passes through it in a direction substantially opposite to the direction of liquid flow through the second chamber. Typically, in use, the third chamber may be located below the second chamber.

[0042] Typically, the liquid exiting the separator can be conveyed to an acid waste treatment plant, which can be part of an exhaust gas abatement system.

[0043] Advantageously, the third chamber may further prevent gaseous components of the exhaust stream from exiting the separator through the third liquid outlet. Alternatively, the gaseous components of the exhaust stream may be urged towards exiting through the gaseous exhaust outlet. Those skilled in the art will appreciate that there may be one or more further chambers after the third chamber, typically arranged so that liquid passes through said chambers in a direction substantially opposite to the direction of liquid flow in the previous chambers.

[0044] The separator may include an inlet diverter configured to direct non-gaseous components of the exhaust stream toward the liquid in the first chamber.

[0045] The separator may comprise a mist extractor. The mist extractor may be configured to substantially prevent the passage of non-gaseous components of the exhaust stream through the gaseous exhaust outlet. Preferably, the mist extractor may provide a physical barrier to the passage of solids and / or liquids through the gaseous exhaust outlet. The mist extractor may cause liquid droplets carried by the gaseous components of the exhaust stream to coalesce and return directly into the first chamber. The mist extractor may be located at or towards the gaseous exhaust outlet. The mist extractor may comprise a wire mesh and / or a plurality of vanes.

[0046] Additionally or alternatively, the separator can include a liquid level sensor in the first chamber. The liquid level sensor can be operably connected to a controller. The controller can be configured to adjust the flow rate and / or pressure of water entering the water eductor. The liquid level sensor and controller can maintain the water level (fill line) in the first chamber at a desired level, for example, below the gaseous exhaust outlet and / or above the first liquid outlet.

[0047] Typically, the water eductor can be configured to substantially prevent backflow of gas through the exhaust outlet of the vacuum pump. Additionally or alternatively, the water eductor can be configured to provide a flow rate of at least 40 slm of nitrogen through the exhaust gas inlet. Preferably, the water eductor can be configured to provide a flow rate of at least 100 slm of nitrogen through the exhaust gas inlet. The water eductor can be configured to provide a flow rate at least equal to the flow rate of nitrogen gas introduced into the exhaust stream. Advantageously, this can substantially prevent backflow of gas through the exhaust outlet in use, improving pump performance.

[0048] Typically, the water flow rate through the nozzle of the water eductor is at least 0.5 gallons per minute (i.e., 2.27304 liters per minute) at 5 psi (i.e., 34.4738 kPa). Preferably, the water flow rate through the nozzle of the water eductor is at least 5 gallons per minute (i.e., 22.7304 liters per minute) at 50 psi (i.e., 344.738 kPa). Advantageously, controlling the pressure and flow rate of water through the nozzle of the water eductor can allow for control of the vacuum created at the inlet of the water eductor.

[0049] In some embodiments, the water eductor can have a length of less than about 200 mm, preferably less than about 160 mm. The water eductor can have a height of less than about 150 mm, preferably less than about 100 mm. The water eductor can have a width of less than about 50 mm, preferably less than about 30 mm.

[0050] Additionally or alternatively, the separator can have a length of less than about 250 mm, preferably less than about 160 mm. The separator can have a height of less than about 150 mm, preferably less than about 100 mm. The separator can have a width of less than about 150 mm, preferably less than about 100 mm.

[0051] Advantageously, the compact design of the water eductor and / or separator can allow them to fit within exhaust gas abatement systems where space is limited. Additionally, the compact design allows the water eductor and separator to be positioned near the exhaust outlet of the vacuum pump, thereby reducing the likelihood of precursor chemical vapor condensing before reaching the water eductor.

[0052] Typically, the water eductor can be configured to be heated to a temperature of at least 100°C during operation. Preferably, the water eductor can be configured to be heated to a temperature of at least 200°C during operation. In some applications, the temperature of the vacuum pump exhaust stream can be from about 100°C to about 200°C, or higher. In such cases, the water eductor can be heated to reduce the likelihood of precursor chemical vapor condensing due to a drop in temperature upon entering the water eductor. The water eductor can include a heating element, such as a heating tape, configured to maintain the water eductor at a selected temperature.

[0053] Typically, the water eductor can be made from a polymeric and / or metallic material. Preferably, the water eductor can be constructed from a single material. The material(s) selected may depend on the application.

[0054] Illustratively, in embodiments in which the water eductor comprises a polymeric material, the material of the water eductor may be selected from the list including polypropylene, chlorinated polyvinyl chloride (CPVC), or Teflon. In embodiments in which the water eductor is made from a metallic material, the material of the water eductor may be selected from the list including stainless steel, acid-resistant Hastelloy, copper, or brass.

[0055] For applications in which the water eductor is heated during use, the water eductor may preferably be fabricated from a metallic material, for example, the water eductor may be constructed from stainless steel.

[0056] For applications where the exhaust gas stream from the vacuum pump contains inorganic acids (eg, hydrofluoric acid or hydrochloric acid), the water eductor may preferably be constructed of Hastelloy steel.

[0057] Advantageously, the selection of a particular material for the water eductor depending on the application can extend component life and / or reduce costs.

[0058] In a further aspect, the present invention provides a method for abating exhaust gases from a semiconductor processing chamber, the method comprising: a. evacuating exhaust from a semiconductor processing chamber by operating a vacuum pump; b. conveying exhaust air from the vacuum pump through a water eductor so that the exhaust air mixes with water; c. conveying the exhaust and water mixture from the water eductor through a separator, thereby separating gaseous components of the exhaust from non-gaseous components; d. Treating the gaseous components of the exhaust with an exhaust gas abatement device; Includes:

[0059] For the avoidance of doubt, the vacuum pump, water eductor, separator and / or further features of the exhaust gas abatement device are as defined in the first aspect and elsewhere herein.

[0060] Typically, step (a) includes operating a vacuum pump to provide a high or ultra-high vacuum within the semiconductor processing chamber. -7 mbar to about 10 -3 Ultra-high vacuum can be defined as a pressure of approximately 10 mbar. -7 It can be defined as a pressure below mbar.

[0061] Typically, the exhaust gas can be diluted with nitrogen gas. Preferably, the exhaust gas can be diluted with nitrogen gas at the exhaust port of the vacuum pump. The exhaust gas can be diluted with nitrogen gas having a flow rate of about 20 slm to about 150 slm. Advantageously, this can reduce the risk of condensation of precursor chemical vapors and reduce the flammability level.

[0062] Preferably, during steps (b) and (c), the water eductor can be heated to a temperature greater than about 100° C., preferably greater than about 200° C. Advantageously, this can reduce the possibility of condensation of the chemical precursor gases as they enter the water eductor, especially when the vacuum pump exhaust gases are at high temperatures (e.g., temperatures greater than 100° C.).

[0063] Preferably, during step (b), the water eductor is capable of providing a vacuum at the exhaust outlet of the vacuum pump to draw exhaust flow into the water eductor. Preferably, the water eductor is capable of providing a vacuum at the exhaust outlet of the vacuum pump sufficient to cause a flow rate at least equal to the flow rate of the nitrogen dilution. More preferably, the water eductor is capable of providing a vacuum sufficient to cause a flow rate of at least 40 slm of nitrogen through the exhaust gas inlet of the water eductor. Advantageously, this can substantially prevent backflow of gas through the exhaust outlet of the vacuum pump.

[0064] In a further aspect, the present invention provides the use of a water eductor and separator in an exhaust gas abatement system for semiconductor manufacturing, the water eductor and separator being positioned between a vacuum pump and an exhaust gas abatement device such that exhaust from the vacuum pump is conveyed to the separator via the water eductor.

[0065] Preferably, the water eductor and separator can be located immediately adjacent to the exhaust outlet of the vacuum pump. The vacuum pump, water eductor, separator, and exhaust gas abatement device can be arranged in series and fluidly connected.

[0066] For the avoidance of doubt, further features of the vacuum pump, water eductor, separator, and / or exhaust gas abatement device are as defined in the above aspects and elsewhere herein.

[0067] Advantageously, the use of water eductors and separators according to the present invention can provide a low-cost, efficient mechanism for removing water-reactive chemical precursor gases from semiconductor processing exhaust gas streams, thereby reducing condensation of said chemical precursor gases in the exhaust line and increasing the mean time between failures of exhaust gas abatement systems, thereby allowing for safer and less scheduled maintenance.

[0068] For the avoidance of doubt, all aspects and embodiments described herein can be combined mutatis mutandis. It is also to be understood that the invention is not limited to the embodiments and aspects described in the following detailed description or illustrated in the drawings. The invention is capable of other various embodiments and of being practiced in alternative ways not expressly disclosed herein.

[0069] It is also to be understood that the phraseology and terminology used herein are for descriptive purposes and should not be regarded as limiting. The use of "including" and "comprising," and variations thereof, means the inclusion of the subsequently listed elements and their equivalents, as well as additional elements and their equivalents. Furthermore, enumerations may be used in describing various embodiments. Unless otherwise indicated, the use of enumerations should not be construed as limiting the invention to a particular order or number of components. Furthermore, the use of enumerations should not be construed as excluding from the scope of the invention additional steps or components that may be combined with or incorporated within the enumerated steps or components.

[0070] Preferred features of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0071] [Figure 1] 1 shows a schematic diagram of a typical prior art semiconductor processing system; [Figure 2]1 shows a cross-sectional view of a water eductor suitable for use in an exhaust gas abatement system according to the present invention. [Figure 3] 1 is a cross-sectional view of a water eductor and separator suitable for use in an exhaust gas abatement system according to the present invention. [Figure 4] 1 is a cross-sectional view of a vacuum pump, water eductor, and separator suitable for use in an exhaust gas abatement system according to the present invention. [Figure 5] 1 shows a flow diagram of a method according to the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0072] Figure 1 shows a schematic diagram of a typical semiconductor processing system of the prior art. The system comprises a semiconductor processing chamber (1) in which single crystal silicon wafers are processed using multiple lithography, deposition, and / or etching steps using various precursor chemical vapors. This processing is carried out under high or ultra-high vacuum. Therefore, the semiconductor processing chamber (1) is connected to a vacuum pump (3) via a foreline (2).

[0073] The vacuum pump (3) is, for example, a dry vacuum pump. In use, the vacuum pump (3) is configured to evacuate the semiconductor processing chamber (1) to a high vacuum. The exhaust flow exits the vacuum pump (3) through the vacuum pump exhaust line (4).

[0074] In use, the exhaust stream in the vacuum pump exhaust line (4) may be diluted with nitrogen gas to reduce the likelihood of condensation of the exhaust stream in the vacuum pump exhaust line (4).

[0075] The nitrogen diluted exhaust stream can be conveyed through a vacuum pump exhaust line (4) to an exhaust gas abatement system (5) where the exhaust gas is treated. This treatment involves subjecting the exhaust gas to high temperatures generated in an internal combustion combustion chamber, a plasma chamber, or an electric arc discharge. The treated exhaust gas can then exit the exhaust gas abatement system (5) through a gas outlet (6).

[0076] In such systems, it has been found that a significant percentage of the precursor chemical vapor exits the semiconductor processing chamber (1) through the foreline (2) in the exhaust stream, passes through the vacuum pump (3), the vacuum pump exhaust line (4), and enters the exhaust gas abatement system (5). This is undesirable because condensation of the precursor chemical vapor can form deposits and react with any water in the system. Deposit formation is particularly common in the vacuum pump exhaust line (4), which has been found to require frequent maintenance.

[0077] 2 shows a cross-sectional view of a water eductor (7) suitable for use in an exhaust gas abatement system according to the present invention. The water eductor (7) includes an inlet (8) configured to be coupled to an exhaust outlet of a vacuum pump (not shown). Preferably, the inlet (8) can be directly connected to the exhaust outlet of the vacuum pump. Alternatively, the inlet (8) can be coupled to the exhaust outlet of the vacuum pump by an exhaust gas line.

[0078] The water eductor (7) further comprises a nozzle (9) configured to inject water. In use, the injected water can provide a driving fluid for the Venturi effect caused by the water eductor (7). In use, pressurized water can be supplied to the nozzle (9) from a pump (not shown). Typically, the flow rate of water through the nozzle (9) of the water eductor (7) is at least 0.5 gallons per minute (i.e., 2.27304 liters per minute) at 5 psi (i.e., 34.4738 kPa), and preferably at least 5 gallons per minute (i.e., 22.7304 liters per minute) at 50 psi (i.e., 344.738 kPa).

[0079] The water eductor further comprises a mixing throat (10). In use, water injected through the nozzle (9) mixes in the mixing throat (10) with the exhaust flow entering through the inlet (8). The cross-sectional area of ​​the water eductor (7) may narrow at the mixing throat (10). This can advantageously improve mixing.

[0080] The water eductor (7) further comprises an expansion diffuser (11) coupled to the mixing throat (10). The chamber defining the expansion diffuser (11) may have a cross-sectional area that increases in a direction toward an outlet (12) of the water eductor (7). The chamber may have a first cross-sectional area adjacent the mixing throat (10) and a second cross-sectional area adjacent the outlet (12) of the water eductor (7), the first cross-sectional area being smaller than the second cross-sectional area. The cross-sectional area of ​​the chamber defining the expansion diffuser (11) may increase substantially continuously between the first cross-sectional area and the second cross-sectional area. The chamber defining the expansion diffuser (11) may be substantially frusto-conical. In use, water and exhaust flow may be channeled through the chamber.

[0081] In use, the water eductor (7) can create a vacuum at the inlet (8) by the Venturi effect, which advantageously draws gases through the exhaust of the vacuum pump and reduces backflow of gases through this exhaust.

[0082] In use, the water eductor (7) may be heated to a temperature of at least 100° C., preferably at least 200° C. Advantageously, this may reduce the likelihood of condensation of precursor chemical vapors that may be present in the exhaust gas stream. In such an embodiment, the water eductor (7) is made from a metallic material, such as stainless steel.

[0083] FIG. 3 shows a cross-sectional view of a water eductor (7) and separator (13) suitable for use in an exhaust gas abatement system according to the present invention.

[0084] The water eductor (7) is as shown in Figure 2, and accordingly corresponding reference numerals are used and a description of its features will not be repeated.

[0085] The separator (13) includes an inlet (14) coupled to the outlet (12) of the water eductor (7). The separator (13) further includes a first chamber (15) including a first liquid outlet (16) and a gaseous exhaust outlet (17). The first chamber (15) is configured to be partially filled with liquid in use, such that the uppermost level of the liquid defines a fill line. In use, as shown in FIG. 4, the first liquid outlet (16) is positioned below the liquid level and the gaseous exhaust outlet (17) is positioned above the liquid level. The gaseous exhaust outlet (17) is connected to an abatement device (not shown).

[0086] The separator (13) further comprises a second chamber (18) having an inlet fluidly connected to the first liquid outlet (16) of the first chamber (15), and a second liquid outlet (19). As shown in Figure 4, the second liquid outlet (19) is arranged so that, in use, liquid passes through the second chamber (18) in a direction substantially opposite to the direction of liquid flow through the first chamber (15).

[0087] The separator (13), in use, is configured to separate gaseous components of the exhaust stream from non-gaseous components of the exhaust stream. The gaseous components of the exhaust stream may include any gases not dissolved in the water in the water eductor (7) and / or gas products of the reaction between the exhaust stream and water. The non-gaseous components may include water, any chemicals dissolved therein, and any solid deposits carried in the water.

[0088] In this embodiment, the separator (13) further comprises a third chamber (20). The third chamber (20) has a liquid inlet fluidly connected to the second liquid outlet (19). The third chamber has a third liquid outlet (21). The third chamber (20) can be positioned such that, in use, liquid passes through the third chamber (20) in a direction substantially opposite to the direction of liquid flow through the second chamber (18). In this embodiment, the third liquid outlet (21) provides an outlet for the separator (13).

[0089] Figure 4 shows a cross-sectional view of a vacuum pump (22), water eductor (7), and separator (13) suitable for use in an exhaust gas abatement system according to the present invention. The water eductor (7) and separator (13) are as described in relation to Figures 2 and 3, respectively, and corresponding reference numerals will be used.

[0090] In use, a semiconductor processing chamber (not shown) is evacuated by a vacuum pump (22). The exhaust stream from the semiconductor processing chamber, and therefore the vacuum pump (22), may contain precursor chemical vapors. A motive water stream (W1) is injected from a nozzle (9) at a predetermined pressure and flow rate. The exhaust stream (G1) exits the vacuum pump (22) and is conveyed to a water eductor (7) through an inlet (8). The water (W1) mixes with the exhaust gas (G1) in a mixing throat (10) to transfer kinetic energy. A majority of the water-reactive components of the exhaust gas stream are soluble in water. Preferably, this includes water-reactive precursor chemical vapors and / or inorganic acids present in the exhaust gas stream.

[0091] The exhaust stream (W2) (i.e., the exhaust gas and water mixture) then exits the mixing throat (10) into the expansion diffuser (11). The cross-sectional area of ​​the chamber defining the expansion diffuser (11) increases toward the outlet (12), causing the velocity of the exhaust stream (W2) to decrease and the pressure to increase. The resulting pressure differential thus creates a vacuum at the inlet (8), drawing the exhaust gas (G1) into the water eductor (7).

[0092] The exhaust stream (W2) then exits the expansion diffuser (11) and enters the first chamber (15) of the separator (13) through the inlet (14). In use, the first chamber (15) is partially filled with liquid such that the uppermost level of the liquid defines the fill line (23). The fill line (23) is maintained such that the first liquid outlet (16) is located below the fill line (23) and the gaseous exhaust outlet (17) is located above the fill line (23).

[0093] The exhaust stream (W2) entering the first chamber (15) of the separator (13) is directed against the inlet diverter or wall (24) of the first chamber (15), which reduces the velocity of the exhaust stream (W2) and allows its non-gaseous components to enter the liquid contained in the first chamber (15). The direction (A) of liquid flow through the first chamber (15) is towards the liquid outlet (16).

[0094] The liquid then enters the second chamber (18). The direction of liquid flow (B) through the second chamber (18) is towards the second liquid outlet (19). This direction (B) is substantially opposite to the direction of liquid flow (A) through the first chamber (15).

[0095] The liquid then enters the third chamber (20). The direction (C) of liquid flow through the third chamber (20) is toward the third liquid outlet (21). This direction (C) is substantially opposite to the direction (B) of liquid flow through the second chamber (18). The first chamber (15) can be positioned above the second chamber (18). The second chamber can be positioned above the third chamber (20).

[0096] The alternating directions (A, B, C) of water flow through the first chamber (15), second chamber (18), and third chamber (20), respectively, can reduce the likelihood that gaseous components of the exhaust stream will exit the separator (13) through the third outlet (21). Instead, the gaseous components (G2) of the exhaust stream are forced to exit the separator (13) through the gaseous exhaust outlet (17).

[0097] Although not shown in this embodiment, a mist diffuser may be present to reduce the likelihood of liquid droplets passing through the gaseous exhaust outlet (17).

[0098] A water level sensor (not shown) may be present in the first chamber (15). The water level sensor may be connected to a controller. The controller may be configured to adjust the flow rate of water through the nozzle (9) to ensure the fill line (23) is maintained at the appropriate level in the first chamber (15).

[0099] Figure 5 shows a flow diagram of a method according to the present invention. For the avoidance of doubt, the features of the vacuum pump, water eductor, separator and exhaust gas abatement device may be as defined in any other aspect or embodiment described herein.

[0100] The method includes evacuating exhaust from the semiconductor processing chamber by operating a vacuum pump (25). This step can include operating the vacuum pump to create a high or ultra-high vacuum in the semiconductor processing chamber. Preferably, the exhaust can be diluted with nitrogen gas as it exits the vacuum pump (26).

[0101] The exhaust gas is then conveyed from the vacuum pump through a water eductor where the exhaust gas is mixed with water (27). Preferably, the water eductor is capable of providing a vacuum at the exhaust outlet of the vacuum pump sufficient to draw the exhaust gas into the water eductor. More preferably, the water eductor is capable of providing a flow rate sufficient to draw at least 40 slm of nitrogen from the exhaust inlet. Preferably, the water eductor is heated to a temperature greater than about 100°C, preferably greater than about 200°C.

[0102] The exhaust and water mixture is then conveyed from the water eductor through a separator, which separates the gaseous components of the exhaust from the non-gaseous components (28).

[0103] The gaseous components are then treated in an exhaust gas abatement system, and the non-gaseous components are discharged through the liquid outlet of the separator (29).

[0104] For the avoidance of doubt, features of any aspect or embodiment recited herein may be combined mutatis mutandis. It is understood that various modifications may be made to the illustrated embodiments without departing from the spirit and scope of the invention as defined in the appended claims as interpreted under patent law, including the doctrine of equivalents. For example, the use of the articles "a," "an," "the," or "said" to refer to a claim element in the singular shall not be deemed to limit the element to the singular. [Explanation of symbols]

[0105] 1. Semiconductor Processing Chamber 2 Foreline 3. Vacuum pump 4 Vacuum pump exhaust line 5 Exhaust gas abatement device 6 Gas outlet 7 Water Eductor 8 Entrance 9 nozzles 10 Mixed Throat 11 Expansion diffuser 12 Exit 13 Separator 14 Entrance 15 First Chamber 16 First liquid outlet 17 Gaseous exhaust outlet 18 Second Chamber 19 Second liquid outlet 20 Third Chamber 21 Third liquid outlet 22 Vacuum pump 23 Filling Line 24 Wall 25 Step 1 26 Step 2 27 Step 3 28 Step 4 29 Step 5

Claims

1. 1. An exhaust gas abatement system for use in semiconductor processing, comprising: a vacuum pump having an exhaust outlet; a water eductor coupled to the exhaust outlet of the vacuum pump; a separator coupled to the water eductor; an exhaust gas abatement device, preferably an abatement furnace, coupled to the gaseous exhaust outlet of the separator; Equipped with The exhaust gas abatement system is configured, in use, such that an exhaust stream from the exhaust outlet of the vacuum pump is conveyed through the water eductor to the separator, the separator being configured, in use, to separate gaseous components of the exhaust stream from non-gaseous components of the exhaust stream.

2. The water eductor is an inlet coupled to the exhaust outlet of the vacuum pump; a nozzle configured to spray water; a mixing throat within which, in use, the injected water mixes with the exhaust flow from the vacuum pump; an expansion diffuser coupled to the mixing throat and defined by a chamber having a cross-sectional area that increases in a direction toward an outlet of the water eductor; The exhaust gas abatement system of claim 1 , comprising:

3. The separator comprises: an inlet coupled to the outlet of the water eductor; a first chamber including a first liquid outlet and the gaseous exhaust outlet, the first chamber configured to be partially filled with liquid such that a top surface of the liquid defines a fill line, the first liquid outlet being located below the fill line and the gaseous exhaust outlet being located above the fill line; a second chamber preferably comprising a liquid inlet in fluid communication with the first liquid outlet of the first chamber, the second chamber having a further liquid outlet, the second chamber being arranged such that, in use, liquid passes through the second chamber in a direction substantially opposite to the direction of liquid flow through the first chamber; The exhaust gas abatement system according to claim 1 or 2, comprising:

4. 4. The exhaust gas abatement system of claim 3, wherein the separator further comprises a third chamber having a liquid inlet fluidly connected to the second liquid outlet and a further liquid outlet, the third chamber being arranged such that liquid passes through the third chamber in a direction substantially opposite to the direction of liquid flow through the second chamber.

5. 5. The exhaust gas abatement system of claim 3 or 4, wherein the separator further comprises an inlet diverter, and / or a mist extractor, and / or a liquid level sensor in the first chamber.

6. 6. The exhaust gas abatement system of claim 1, wherein the water eductor is configured to substantially prevent backflow of gas through the exhaust outlet of the vacuum pump, and / or the water eductor is configured to provide a flow rate of at least 40 slm of nitrogen through the inlet.

7. 7. The exhaust gas abatement system of claim 1, wherein the flow rate of water through the nozzle of the water eductor is at least 0.5 gallons per minute at 5 psi, preferably at least 5 gallons per minute at 50 psi.

8. 8. The exhaust gas abatement system of any one of claims 1 to 7, wherein the water eductor has a length of less than about 200 mm, preferably less than about 160 mm, a height of less than about 150 mm, preferably less than about 100 mm, and a depth of less than about 50 mm, preferably less than about 30 mm.

9. 9. The exhaust gas abatement system of claim 1, wherein the separator has a length of less than about 250 mm, preferably less than about 160 mm, a height of less than about 150 mm, preferably less than about 100 mm, and a width of less than about 150 mm, preferably less than about 100 mm.

10. 10. An exhaust gas abatement system according to any preceding claim, wherein the water eductor is configured to be heated to a temperature of at least 100°C, preferably at least 200°C, during operation.

11. 11. The exhaust gas abatement system of any of claims 1 to 10, wherein the water eductor is made from a polymeric material and / or a metallic material.

12. 1. A method for abating exhaust gases from a semiconductor processing chamber, comprising: a. evacuating exhaust from the semiconductor processing chamber by operating a vacuum pump; b) conveying the exhaust gas exiting the vacuum pump through a water eductor so that the exhaust gas mixes with water; c) conveying the exhaust and water mixture from the water eductor through a separator, thereby separating gaseous components of the exhaust from non-gaseous components; d. treating the separated gaseous components of the exhaust in an exhaust gas abatement system; A method comprising:

13. 13. The method of claim 12, wherein during steps (b) and (c), the water eductor is heated to a temperature above about 100°C, preferably above about 200°C.

14. 14. The method of claim 12 or 13, wherein during step (b), the water eductor provides a vacuum to the exhaust outlet of the vacuum pump to draw the exhaust air into the water eductor.

15. Use of a water eductor and a separator in an exhaust gas abatement system for semiconductor manufacturing, wherein the water eductor and the separator are disposed between a vacuum pump and an exhaust gas abatement device, and exhaust from the vacuum pump is conveyed to the separator via the water eductor.

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