Optimization of operating conditions in abatement equipment

Abstract

A method of optimizing operating conditions in an abatement apparatus configured to process an effluent stream from a process tool and an abatement apparatus are disclosed. The method of optimizing operating conditions in an abatement apparatus configured to process an effluent stream from a process tool includes determining a concentration of carbon monoxide produced by the abatement apparatus when processing the effluent stream and adjusting an operating parameter of the abatement apparatus in response to the concentration of carbon monoxide. In this manner, the performance of the abatement apparatus can be controlled by simply adjusting the operating parameter of the abatement apparatus in response to the amount of carbon monoxide produced to create conditions within the abatement apparatus that improve the removal of compounds being processed within the abatement apparatus while reducing undesirable byproducts without requiring prior knowledge of the contents of the effluent stream.

Description

Technical Field

[0001] The field of the present invention relates to a method for optimizing operating conditions in a reduction device and a reduction device configured to process outflow material from a processing tool. Background Technology

[0002] Mitigation devices are known and commonly used to treat effluent streams from manufacturing tools used in industries such as semiconductors or flat panel displays. During such manufacturing processes, residual harmful and / or global warming gases remain in the effluent streams pumped from the tool. Due to their nature and because they are known to have adverse environmental impacts, they are also undesirable and should be removed from the effluent streams before they are released into the atmosphere.

[0003] Known attenuation devices, such as radiant burners, use combustion to remove unwanted compounds from the outflow gas stream to meet target concentrations in the exhaust gas stream from the attenuation device. Typically, the outflow gas stream is a nitrogen stream containing residual gases such as hydrogen, ammonia, tetraethoxysilane (TEOS), and / or nitrous oxide, as well as other compounds depending on the processing steps performed in the processing tool. Fuel gas and / or oxidizer gas are mixed with the outflow gas stream, and this gas-gas mixture is conveyed into a combustion chamber laterally surrounded by the exit surface of an orifice gas burner. Fuel gas and air are simultaneously supplied to the orifice burner to achieve flameless combustion at the exit surface; the amount of air passing through the orifice burner is not only sufficient to consume the combustion gas supplied to the burner but also helps to eliminate combustibles from the gas-gas mixture injected into the combustion chamber.

[0004] Hydrogen, ammonia, and TEOS are oxidizable gases and typically present in significant concentrations in the effluent stream, but additional oxidants (such as air or oxygen) need to be added to the effluent stream to achieve the desired reduction levels. US8647111 discloses that an ammonia / hydrogen mixture can be combusted by adding an appropriate amount of air. US5938422 discloses that TEOS can be destroyed by mixing with oxygen before combustion in the combustion zone.

[0005] Nitrous oxide is an oxidizing gas that, ideally, should be reduced to nitrogen by adding fuel gas when it is injected into the combustion chamber. Incomplete reduction of nitrous oxide leads to the formation of nitric oxide and nitrogen dioxide (collectively known as NOx), unwanted byproducts that contribute to acid rain and other environmental problems.

[0006] Although techniques for processing outflowing airflow exist, they all have their own drawbacks. Therefore, it is desirable to provide an improved technique for processing outflowing airflow. Summary of the Invention

[0007] According to a first aspect, a method is provided for optimizing operating conditions in a carbon monoxide removal device configured to process an outflow material from a processing tool, the method comprising: determining the concentration of carbon monoxide generated by the carbon monoxide removal device when processing the outflow material; and adjusting operating parameters of the carbon monoxide removal device in response to the concentration of carbon monoxide.

[0008] The first aspect recognizes that existing solutions for treating effluent streams can be problematic because it may be difficult to set the operating conditions of the effluent treatment equipment to effectively treat the effluent. Furthermore, some operating conditions that might be suitable for treating the effluent may lead to the generation of undesirable byproducts. Additionally, existing solutions may be complex and / or require prior knowledge of the composition of the effluent being treated. However, the first aspect recognizes that by monitoring the presence of carbon dioxide during effluent treatment, operating conditions can be optimized to remove gases from the treated effluent and reduce undesirable byproducts. Therefore, a method is provided. This method can be used to optimize or adjust the operation of a effluent treatment equipment that treats effluent streams from processing tools. The method may include determining or identifying the concentration of carbon monoxide generated or present when the effluent treatment equipment treats the effluent. The method may include adjusting or changing the operating parameters or operation of the effluent treatment equipment in response to the generated or present carbon monoxide. Adjusting the operating parameters will adjust the operation of the effluent treatment equipment. In this way, the performance or operation of the reduction device can be controlled by simply adjusting the operating parameters of the reduction device in response to the amount of carbon monoxide generated. This creates improved conditions for the removal of compounds processed in the reduction device compared to the conditions before adjustment, while reducing unwanted byproducts and eliminating the need for prior knowledge of the contents of the effluent stream.

[0009] In one embodiment, the determination includes measuring the concentration of carbon monoxide present in the exhaust gas of the mitigation device. Therefore, the amount of carbon monoxide present in the exhaust gas of a mitigation device comprising a treated effluent stream can be measured.

[0010] In one embodiment, determination includes measuring the concentration of carbon monoxide using an infrared spectrometer. Therefore, carbon monoxide can be measured by infrared spectroscopy, which is less prone to contamination or degradation and has high specificity for the target analyte. Infrared sensors are highly responsive and can recover rapidly if the analyte becomes saturated.

[0011] In one embodiment, the operating parameters include the fuel / oxidizer ratio. Therefore, the amount of fuel and oxidizer supplied to the depletion unit can be adjusted in response to the carbon monoxide concentration.

[0012] In one embodiment, the adjustment includes changing the fuel / oxidizer ratio to reduce the concentration of carbon monoxide. Therefore, the amounts of fuel and oxidizer can be varied to reduce the amount of carbon monoxide.

[0013] In one embodiment, the adjustment includes determining whether changing the fuel / oxidizer ratio reduces the concentration of carbon monoxide, and if so, maintaining the change. Therefore, if a change in the amount of fuel and oxidizer results in a reduction in the amount of carbon monoxide, then the change in the amount of fuel and oxidizer is maintained.

[0014] In one embodiment, the adjustment includes determining whether changing the fuel / oxidizer ratio would increase the concentration of carbon monoxide, and if so, reversing the change. Therefore, if a change in the amount of fuel and oxidizer results in an increase in the amount of carbon monoxide, then the change made to the amount of fuel and oxidizer is abandoned.

[0015] In one embodiment, the adjustment includes changing the supply of the oxidizer. Therefore, the fuel-air ratio can be changed by altering the amount of oxidizer supplied to the decompression unit. This allows the fuel supply to remain constant, thus allowing adjustment to be made by changing only one component.

[0016] In one embodiment, the adjustment includes increasing the supply of oxidant, determining whether the concentration of carbon monoxide has increased, and if so, reducing the supply of oxidant. Therefore, the amount of oxidant can be increased, and if the concentration of carbon monoxide thus increases, the increase in the amount of oxidant can be reversed.

[0017] In one embodiment, the adjustment includes reducing the supply of oxidant, determining whether the concentration of carbon monoxide has increased, and if so, increasing the supply of oxidant. Therefore, the amount of oxidant can be reduced, and if the amount of carbon monoxide thus increases, the reduction in the amount of oxidant can be reversed.

[0018] It should be understood that the above scheme helps to identify the minimum amount of carbon monoxide produced, for example, in situations encountered when processing outflows containing excess hydrogen.

[0019] In one embodiment, the adjustment includes determining whether changing the fuel / oxidizer ratio reduces the carbon monoxide concentration toward a threshold amount, and if so, maintaining the change. Therefore, if a change in the amount of fuel and oxidizer results in an amount of carbon monoxide produced that is closer to the carbon monoxide threshold amount than before the change, the change can be maintained.

[0020] In one embodiment, the adjustment includes determining whether changing the fuel / oxidizer ratio reduces the carbon monoxide concentration below a threshold amount, and if so, reversing the change. Therefore, if a change in the amount of fuel and oxidizer results in a decrease in the amount of carbon monoxide below a threshold amount, then the change in the amount of fuel and oxidizer can be abandoned.

[0021] In one embodiment, the adjustment includes changing the fuel supply. Therefore, the amount of fuel supplied to the decompression unit can be varied. This allows the amount of oxidizer supplied to the decompression unit to remain constant.

[0022] In one embodiment, the adjustment includes determining whether the carbon monoxide concentration is above a threshold amount, and if so, reducing the fuel supply. Therefore, if the amount of carbon monoxide is determined to exceed a threshold amount, the fuel supply can be reduced.

[0023] In one embodiment, the adjustment includes determining whether the carbon monoxide concentration is below a threshold amount, and if so, increasing the fuel supply. Therefore, if it is determined that the amount of carbon monoxide fails to reach a threshold amount, the amount of fuel supplied to the mitigation equipment can be increased.

[0024] It should be understood that the above scheme helps to identify acceptable target amounts of carbon monoxide produced, for example, in situations encountered when processing effluent streams containing excessive nitrous oxide.

[0025] In one embodiment, the adjustment includes changing the supply of the oxidizer. Therefore, the amount of oxidizer supplied to the decompression unit can be varied. This allows the amount of fuel supplied to the decompression unit to remain constant.

[0026] In one embodiment, the adjustment includes determining whether the concentration of carbon monoxide is above a threshold amount, and if so, reducing the supply of oxidant. Therefore, if it is determined that the amount of carbon monoxide exceeds a threshold amount, the supply of oxidant can be reduced.

[0027] In one embodiment, the adjustment includes determining whether the carbon monoxide concentration is below a threshold amount, and if so, increasing the supply of oxidant. Therefore, if it is determined that the amount of carbon monoxide fails to reach a threshold amount, the amount of oxidant supplied to the reduction device can be increased.

[0028] It should be understood that the above scheme helps to determine the acceptable target amount of carbon monoxide produced, for example, when processing outflows containing excessive TEOS.

[0029] According to a second aspect, there is provided an apparatus for adjusting operating conditions in a carbon monoxide reduction device configured to process an outflow material from a processing tool, the apparatus comprising: a sensor configured to determine the concentration of carbon monoxide generated by the carbon monoxide reduction device when processing the outflow material; and a controller operable to adjust operating parameters of the carbon monoxide reduction device in response to the carbon monoxide concentration.

[0030] In one embodiment, the sensor is configured to measure the concentration of carbon monoxide present in the exhaust gas of the decompression device.

[0031] In one embodiment, the sensor is an infrared spectrometer.

[0032] In one embodiment, the operating parameters include the fuel / oxidizer ratio.

[0033] In one embodiment, the controller is operable to change the fuel / oxidant ratio to reduce the concentration of carbon monoxide.

[0034] In one embodiment, the controller is operable to determine whether changing the fuel / oxidizer ratio reduces the concentration of carbon monoxide, and if so, maintains the change.

[0035] In one embodiment, the controller is operable to determine whether changing the fuel / oxidizer ratio increases the concentration of carbon monoxide, and if so, to reverse the change.

[0036] In one embodiment, the controller is operable to change the supply of oxidant.

[0037] In one embodiment, the controller is operable to increase the supply of oxidant, determine whether the concentration of carbon monoxide has increased, and if so, reduce the supply of oxidant.

[0038] In one embodiment, the controller is operable to reduce the supply of oxidant, determine whether the concentration of carbon monoxide has increased, and if so, increase the supply of oxidant.

[0039] In one embodiment, the controller is operable to determine whether changing the fuel / oxidizer ratio reduces the carbon monoxide concentration toward a threshold amount, and if so, maintains the change.

[0040] In one embodiment, the controller is operable to determine whether changing the fuel / oxidizer ratio reduces the carbon monoxide concentration below a threshold amount, and if so, reverses the change.

[0041] In one embodiment, the controller is operable to change the fuel supply.

[0042] In one embodiment, the controller is operable to determine whether the carbon monoxide concentration is above a threshold amount, and if so, to reduce the fuel supply.

[0043] In one embodiment, the controller is operable to determine whether the carbon monoxide concentration is below a threshold amount, and if so, to increase the fuel supply.

[0044] In one embodiment, the controller is operable to change the supply of oxidant.

[0045] In one embodiment, the controller is operable to determine whether the concentration of carbon monoxide is above a threshold amount, and if so, to reduce the supply of oxidant.

[0046] In one embodiment, the controller is operable to determine whether the carbon monoxide concentration is below a threshold amount, and if so, to increase the supply of oxidant.

[0047] Further specific and preferred aspects are set forth in the appended independent and dependent claims. Features of the dependent claims may be suitably combined with features of the independent claims, or combined in a manner different from that expressly set forth in the claims.

[0048] When a device feature is described as operable to provide a function, it should be understood that this includes device features that provide that function or are adapted or configured to provide that function. Attached Figure Description

[0049] Embodiments of the invention will now be described further with reference to the accompanying drawings, in which:

[0050] Figure 1 An inward-firing combustion reduction device according to one embodiment is shown;

[0051] Figure 2 This is a graph showing the CO, H2 (multiplied by 10 to fit the same scale as O2) and O2 content in the exhaust gas relative to the H2 flow rate in 200 slm N2, with 500 slm of air via a coaxial concentric air inlet and 40 slm of air via each central spray gun addition port.

[0052] Figure 3 This is a graph showing the CO in the exhaust gas for a mixture of NH3 and H2 with different amounts of air added via a coaxial concentric air inlet and a central spray gun port;

[0053] Figure 4 This is a graph showing the CO, H2 (multiplied by 10 to fit the same scale as O2), and O2 content in the exhaust gas relative to the H2 flow rate in 200 slm N2, under the condition that the air addition via a coaxial concentric air inlet is controlled to minimize CO in the exhaust gas.

[0054] Figure 5 It is a graph showing the airflow required to minimize CO in the exhaust gas under different operating conditions;

[0055] Figure 6 This is a schematic flowchart illustrating optimized airflow control for reducing H2 / NH3 mixtures by monitoring CO emissions;

[0056] Figure 7 This is a graph showing the CO in the exhaust gas relative to the N2O in the outflow stream inlet (diluted with 200 slm of N2) for different amounts of CH4 added via the central spray gun addition port;

[0057] Figure 8 It is shown in Figure 6 The graph shows the percentage conversion rate of N2O to NOx (NO + NO2) under the conditions shown—the dashed line indicates the region where CO in the exhaust gas is 200 ppm;

[0058] Figure 9 It shows Figure 6 The graph shows the elimination efficiency (DRE) of N2O under the conditions shown—the dashed line indicates the region where CO in the exhaust gas is 200 ppm;

[0059] Figure 10 It is a graph showing the amount of CH4 required to achieve 200 ppm CO in exhaust gas relative to the N2O supply and the corresponding DRE of N2O;

[0060] Figure 11 This is a schematic flowchart of optimized fuel injection control to reduce N2O by monitoring CO emissions;

[0061] Figure 12 This is a graph showing methane and nitric oxide emissions as functions of concentric methane flow rate and oxygen injection for a nitrogen load on a 300 slm nozzle;

[0062] Figure 13 This is a graph showing the minimum CH4 injection flow rate relative to the nitrogen load;

[0063] Figure 14 This is a graph showing the concentrations of carbon monoxide and carbon dioxide in the exhaust gas as a function of TEOS flow rate for 600 slm N2, 34 slm CH4 and 80-120 slm O2.

[0064] Figure 15 This is a graph showing the limiting oxygen injection required to produce 100 ppmCO in the exhaust gas relative to TEOS at 200 and 300 slm N2 leading to the nozzle; and

[0065] Figure 16 This is a schematic flowchart of optimized fuel injection control to reduce TEOS by monitoring CO emissions. Detailed Implementation

[0066] Before discussing the embodiments in more detail, an overview will first be provided. The embodiments provide a technique in which operating conditions within a depletion device are controlled to provide improved treatment of gases present in the effluent from processing tools without resulting in undesirable amounts of byproducts by measuring the amount of carbon monoxide generated during the treatment of the effluent stream. This allows for improved performance of the depletion device without prior knowledge of the compounds present in the effluent stream. Specifically, a gas sensor dedicated to carbon monoxide concentration in the device exhaust is used to monitor the performance of the depletion device for the controlled combustion of combustible gases such as hydrogen and hydrogen / ammonia mixtures, or for the elimination of oxidizing gases such as nitrous oxide or TEOS. The response of carbon monoxide concentration to the addition of an auxiliary oxidant (e.g., air or oxygen) or fuel (e.g., hydrogen, methane, or propane) is used to obtain optimal conditions for removing the treated gas while minimizing undesirable byproducts (e.g., nitric oxide and nitrogen dioxide). This method does not require prior knowledge of the amount of the target gas to be destroyed, but relies on adjusting the operating parameters of the depletion device.

[0067] As is well known, existing combustion reduction equipment is used to eliminate various gases used in semiconductor device manufacturing. Reducing combustible gases such as hydrogen and hydrogen / ammonia mixtures requires an oxygen source, such as air, to allow complete combustion to occur. Similarly, oxidizer gases such as nitrous oxide require a fuel, such as methane, to reduce nitrous oxide (in this case) to nitrogen. In the case of nitrous oxide, improper addition of fuel gases can lead to the generation of unwanted nitric oxide and nitrogen dioxide (collectively, NOx). The permissible levels of unreduced target gases in exhaust gases can be limited by their absolute concentration (i.e., below their flammability limit), emission rate (mass per unit time), or relative elimination efficiency (DRE). Byproduct emissions may also be required to be below a certain level. The purpose of reduction equipment is to meet or exceed these limits while using minimal resources.

[0068] In some cases, the concentration of the gas to be eliminated can be transmitted to the elimination device digitally or analogically. This allows for optimization of the elimination operation in terms of resources used. In other cases, this may not be possible due to cost, site infrastructure, or other business reasons. The embodiments attempt to monitor performance and adjust operating parameters individually.

[0069] Elimination equipment

[0070] Figure 1An inward-firing combustion reduction device 10 according to one embodiment is shown. The reduction device 10 includes an inward-firing, orifice-mounted burner 20 supplied with a hydrocarbon fuel (typically methane or propane) / air mixture that provides a heat zone and ignition source for the chemical elimination of target compounds in the effluent stream, which is introduced into a combustion chamber 30 at the burner core via an inlet pipe 40 terminating at a nozzle 50. Typically, fuel is supplied from a fuel inlet 100 to a pressurization chamber 90 under the control of a controller 120 to supply the orifice-mounted burner 20.

[0071] Nozzle 50 is provided with an auxiliary port, which is positioned as a center spray gun 60 or a coaxial ring 70 (supply by a common pressurization chamber 80), for introducing fuel gas or oxidant supplied under the control of controller 120 to help eliminate these compounds to be treated. Typically, under the control of controller 120, a fuel / oxidant mixture is supplied to pressurization chamber 90 via center spray gun 60 and fuel / oxidant inlet 110 to supply coaxial ring 70.

[0072] An infrared spectrometer 130 is installed to measure the CO concentration in the exhaust gas from the combustion chamber 30.

[0073] A water weir and a quenching section (not shown) are located downstream of the combustion chamber 30 for cooling the exhaust gas, and a packed tower (not shown) is provided for absorbing water-soluble gases.

[0074] Elimination – Hydrogen or hydrogen / ammonia mixture

[0075] Adding air around nozzle 50 to provide sufficient oxygen for the complete combustion of these materials helps to reduce combustible gases, such as hydrogen or a hydrogen / ammonia mixture. In the absence of sufficient air, combustion chamber 30 becomes oxygen-deficient, and the exhaust gas from reduction device 10 contains incomplete combustion products. In the presence of excess air, the perforated burner 20 is cooled to the point where fuel combustion is extinguished, and incomplete combustion products are again observed in the exhaust gas. In extreme cases of insufficient or excessive air supply, unburned hydrogen is detected in the exhaust gas. For ammonia, unburned gases will primarily dissolve in the water-washed packed tower downstream of the burner assembly, although some gases may escape into the exhaust gas.

[0076] An example of this situation is in Figure 2The diagram shows an air flow rate of 500 slm around nozzle 70, while the hydrogen flow rate (diluted with 200 slm of nitrogen) is increased to 400 slm. An additional 40 slm of compressed dry air is supplied to the spray gun 60 located at the center of each nozzle 70. The concentrations of carbon monoxide (CO), hydrogen, and oxygen in the exhaust stream are shown. With the addition of hydrogen, the oxygen concentration decreases monotonically, but the CO concentration exhibits a U-shaped curve, with the lowest CO level corresponding to the air flow rate region where hydrogen is completely destroyed. The concentrations of hydrogen and oxygen are measured by an electrochemical unit, while the CO concentration is measured by infrared spectroscopy using an infrared spectrometer 130. Electrochemical units are prone to contamination, cross-sensitivity, and degradation, while infrared spectroscopy is highly selective and protected against contamination or degradation. While CO can be measured using catalytic combustion sensors, these sensors are cross-sensitive to the presence of other combustible gases and are unreliable in environments with limited oxygen availability. Infrared sensors also have a fast response time and are less prone to saturation problems.

[0077] Figure 3 The same trend is shown, where the concentration of CO in the exhaust gas is plotted relative to the amount of air added around the inlet nozzle for different mixtures of hydrogen and increased amounts of ammonia in 200 slm nitrogen. Similarly, CO emissions follow a U-shaped curve, with the minimum value coinciding with optimal reduction performance.

[0078] Figure 4 The emissions are shown with an increased amount of added hydrogen, whereby the amount of added air is controlled via a feedback loop between an infrared spectrometer 130 and an air flow controller to minimize CO concentration in the exhaust. This air flow controller, under the control of a controller 120, regulates the amount of air supplied to the combustion chamber 30. Note that for hydrogen concentrations below 200 slm, the air flow is uncontrolled at a baseline level of 400 slm. Minimizing CO has the auxiliary effect of maintaining a constant oxygen level in the exhaust. For the reasons disclosed above, monitoring CO is much easier than monitoring O2.

[0079] Figure 5 It shows that for Figure 3-5 The air flow rate added for different amounts of hydrogen or hydrogen and ammonia (for the sake of illustrating the oxygen required for combustion, one molecule of ammonia is considered as 1.5 molecules of hydrogen) is considered. Above the lower limit of 400 slm air, these points follow a similar trend in the amount of air added to minimize CO emissions, demonstrating that this is a feasible means of feedback control for optimal elimination of these gas mixtures.

[0080] Elimination and optimization – hydrogen or hydrogen / ammonia mixture

[0081] Figure 6This is a schematic flowchart outlining the main steps performed by the controller 120 when optimizing the operating conditions within the combustion chamber 30 to handle the effluent stream containing hydrogen or a hydrogen / ammonia mixture.

[0082] In step S1, the outflow material is processed within the combustion chamber 30, where the controller 30 provides a default or preset amount of fuel and oxidant (air in this example). Processing proceeds to step S2.

[0083] In step S2, the amount of CO in the exhaust gas is determined by infrared spectrometer 130. The processing then proceeds to step S3.

[0084] In step S3, controller 130 increases the oxidant to fuel / H2 / NH3 ratio. In this example, this is achieved by increasing the amount of air supplied to combustion chamber 30. Processing proceeds to step S4.

[0085] In step S4, the controller 130 determines whether the amount of CO in the exhaust gas, as measured by the infrared spectrometer 130, has increased. If the amount of CO has decreased, the process returns to step S3. If the amount of CO has increased, the process proceeds to step S5.

[0086] In step S5, controller 130 reduces the oxidant to fuel / H2 / NH3 ratio. In this example, this is achieved by reducing the amount of air supplied to combustion chamber 30. Processing proceeds to step S6.

[0087] In step S6, the controller 130 determines whether the amount of CO in the exhaust gas, as measured by the infrared spectrometer 130, has decreased. If the amount of CO has decreased, the process returns to step S3. If the amount of CO has increased, the process proceeds to step S5.

[0088] As mentioned above, and as from Figure 3 As can be seen, through this scheme, the operating conditions of combustion chamber 30 can be adjusted to follow the curve shown in the figure to minimize the amount of CO present in the exhaust gas. This optimizes the reduction of the H2 / NH3 mixture and reduces the amount of H2 present in the exhaust gas. It should be understood that in other embodiments, an adaptive algorithm may be used.

[0089] Reduce nitrous oxide

[0090] Another embodiment of this scheme is... Figure 7The diagram illustrates the elimination of nitrous oxide (N2O) diluted with 200 slm of nitrogen. N2O can be reduced to nitrogen by reacting with fuels such as methane (CH4), which is added to the inlet flow via a spray gun 60 at the center of nozzle 50. Undesirable side reactions may also produce nitrogen oxides (nitric oxide (NO) and nitrogen dioxide (NO2), collectively referred to as "NOx") as byproducts. The graph shows the reduction of CO with different amounts of CH4 added to spray gun 60. Excess CH4 relative to N2O again leads to its incomplete oxidation and the production of CO. A dashed line is drawn on the graph at the desired CO level of 200 ppm in the exhaust. By employing an infrared spectrometer 120 in the exhaust and a feedback loop using a controller 120 to control a methane flow controller (not shown), the CO level present in the exhaust can be selected, thereby optimizing NOx formation and maximizing N2O elimination.

[0091] Figure 8 The NOx production from N2O elimination is shown under different CH4 addition levels. The production of this unwanted byproduct varies with N2O flow rate and injection flow rate, and the dashed line on the graph indicates the NOx production when the CO concentration in the exhaust gas is 200 ppm.

[0092] Figure 9 The reduction efficiency (DRE) of N2O is shown under different fuel addition levels. The dashed line indicates the DRE produced by adding sufficient CH4 to achieve a CO concentration of 200 ppm in the exhaust. Therefore, a good trade-off between effective N2O removal and NOx generation can be found. Other target CO concentrations in the exhaust can be selected based on the relative importance of these parameters (e.g., low NOx versus low CO).

[0093] Figure 10 The variation in CH4 addition required to achieve a DRE of 200 ppm carbon monoxide and N2O in the exhaust gas is shown. As with the previous examples, this demonstrates the feasibility of using a CO sensor for feedback control of the added reagent gas to optimize reduction.

[0094] Reduction and optimization - nitrous oxide

[0095] Figure 11 This is a schematic flowchart outlining the main steps performed by the controller 120 when optimizing the operating conditions within the combustion chamber 30 to handle the effluent stream containing a mixture of nitrous oxide.

[0096] In step S10, the outflow material is processed within the combustion chamber 30, where the controller 30 provides a default or preset amount of fuel and oxidant (air in this example). Processing proceeds to step S11.

[0097] In step S11, the amount of CO in the exhaust gas is determined by infrared spectrometer 130. The processing then proceeds to step S12.

[0098] In step S12, the controller 120 determines whether the amount of CO in the exhaust gas measured by the infrared spectrometer 130 exceeds a threshold. In this example, the threshold is 200 ppm, but it should be understood that other thresholds can be used. If the amount of CO in the exhaust gas is higher than the threshold, the processing proceeds to step S13. If the amount of CO in the exhaust gas is not higher than the threshold, the processing proceeds to step S14.

[0099] In step S13, controller 120 reduces the fuel-to-oxidant ratio, where the oxidant is N2O in this example. In this example, this is achieved by reducing the amount of fuel supplied to combustion chamber 30. Processing returns to step S12.

[0100] In step S14, controller 120 increases the fuel-to-oxidant ratio, where the oxidant is N2O in this example. In this example, this is achieved by increasing the amount of fuel supplied to combustion chamber 30. Processing returns to step S12.

[0101] As mentioned above, from Figure 7 As can be seen, through this scheme, the operating conditions of combustion chamber 30 can be adjusted to follow the curve shown in the figure to reduce the amount of CO present in the exhaust gas below the threshold amount, which optimizes the reduction of the N2O mixture. It should be understood that in other embodiments, adaptive algorithms may be used.

[0102] Reduce - TEOS

[0103] One embodiment provides a method for optimizing tetraethyl orthosilicate (TEOS) reduction using an exhaust gas sensor. A key indicator of incomplete TEOS reduction is carbon monoxide formation. The CO concentration in the exhaust gas is monitored using a suitable sensor (e.g., infrared spectroscopy using an infrared spectrometer 130), and the amount of oxygen added is adjusted accordingly to achieve the desired amount.

[0104] Many semiconductor manufacturers use pressure swing adsorption (PSA) devices to extract oxygen from the air, typically achieving a purity of 90-95%. Ideally, this could be monitored and used to adjust the injection flow rate accordingly. This is difficult to do accurately and in a timely manner; therefore, strategies for adjusting the injection flow rate to achieve CO limits in the exhaust gas are adapted to oxygen of unknown purity.

[0105] Tetraethyl orthosilicate, formally named tetraethoxysilane, abbreviated as TEOS, is a compound with the chemical formula Si(OC2H5)4. TEOS is a colorless, volatile liquid that degrades in water. TEOS is an ethyl ester of orthosilicate Si(OH)4. It is the most common silanolate widely used in semiconductor manufacturing for depositing silicon dioxide coatings on wafers.

[0106] Although TEOS is less toxic than its methyl ester analog Si(OCH3)4, its release into the environment is undesirable. TEOS is readily hydrolyzed in water into hydrated silica and ethanol, but this often produces foam, so wet washing of TEOS is not recommended.

[0107] According to the following equation, TEOS is flammable:

[0108] Si(C2H5O)4 + 12 O2 = SiO2 + 8 CO2 + 10 H2O

[0109] In practice, TEOS is difficult to ignite, requiring an ignition source such as a flame, and is typically mixed with oxygen before combustion. Insufficient oxygen will lead to incomplete combustion and cause bubbling in the burner's vent canister. Excess oxygen is a waste of resources. Often, the purity of the oxygen supplied to the attenuation equipment is unknown, therefore predicting the incoming TEOS flow rate to set an appropriate oxygen flow rate is insufficient. The embodiments provide a method for deriving the optimal oxygen addition rate.

[0110] Figure 12 This is a curve showing methane (CH4) and NOx emissions as a function of concentric methane fuel around nozzle 50. TEOS is not used at this stage; the point where NOx appears in the exhaust is used to determine the minimum amount of methane around nozzle 50 sufficient to form a stable flame under these conditions. This is a function of nozzle nitrogen load, as... Figure 13 As shown, this implies a linear relationship with a negative intercept, although the required fuel quantity is likely to plateau at a lower level. In this way, concentric methane flow rates can be established to accommodate operating parameters.

[0111] The required methane concentration around the flame at nozzle 50 has been established; therefore, reducing the amount of oxygen required for TEOS can be considered. Figure 14 The data presented (for 600 slm N2 and increased TEOS) shows that an arbitrary (target threshold) CO level of 100 ppm in the exhaust can be used to define the limit reduction capacity at three different O2 levels. Figure 15 These limits for nitrogen loads at different nozzles are shown.

[0112] Although there are only 3 points for each flow rate, the results for 300 slm and 600 slm appear to lie on a straight line, with slopes of 1.19 and 1.11 liters of O2 per gram of TEOS, respectively. The stoichiometry for the complete combustion of TEOS is given above. Therefore, 1 mole of TEOS requires 12 moles of O2. Since the molecular weight of TEOS is 208.33 g / mol, then 1 gram of TEOS requires 12 × 22.4 / 208.33 liters of oxygen. This is approximately 1.29 liters per gram of TEOS, close to... Figure 15 The slope of the straight line.

[0113] Therefore, a set of parameters can be defined for reducing TEOS in nitrogen gas:

[0114] CH4 (concentric, in slm) = 0.064 nozzle N2 (in slm) – 5.2

[0115] O2 (spray gun, in slm) = 1.15 g / min TEOS + (nozzle N2, in slm) / 10⁻¹⁵

[0116] In practice, while nitrogen flow rate is known and stable, TEOS flow rate is often unknown, and the purity of oxygen available for elimination equipment is less than 100%. To overcome this, carbon monoxide sensors (e.g., infrared spectrometer 130) are used to obtain the appropriate oxygen flow rate level by simply adjusting their setpoints until the CO in the exhaust gas reaches the desired threshold amount.

[0117] Reduce and optimize - TEOS

[0118] Figure 16 This is a schematic flowchart outlining the main steps performed by the controller 120 when optimizing the operating conditions within the combustion chamber 30 to handle the outflow stream containing a TEOS mixture.

[0119] In step S20, the outflow material is processed within the combustion chamber 30, where the controller 30 provides a default or preset amount of fuel and oxidant (oxygen in this example). Processing proceeds to step S21.

[0120] In step S21, the amount of CO in the exhaust gas is determined by infrared spectrometer 130. The processing then proceeds to step S22.

[0121] In step S22, the controller 120 determines whether the amount of CO in the exhaust gas measured by the infrared spectrometer 130 exceeds a threshold. In this example, the threshold is 100 ppm, but it should be understood that other thresholds can be used. If the amount of CO in the exhaust gas is higher than the threshold, the processing proceeds to step S23. If the amount of CO in the exhaust gas is not higher than the threshold, the processing proceeds to step S24.

[0122] In step S23, controller 120 increases the oxidant-to-fuel ratio. In this example, this is achieved by increasing the amount of oxygen supplied to combustion chamber 30. Processing returns to step S22.

[0123] In step S24, controller 130 reduces the oxidant-to-fuel ratio. In this example, this is achieved by reducing the amount of oxygen supplied to combustion chamber 30. Processing returns to step S22.

[0124] As mentioned above, from Figure 14 As can be seen, through this scheme, the operating conditions of combustion chamber 30 can be adjusted to follow the curve shown in the figure to reduce the amount of CO present in the exhaust gas to below the threshold level, which optimizes the reduction of the TEOS mixture. It should be understood that in other embodiments, adaptive algorithms may be used.

[0125] Therefore, it can be seen that the examples use sensors specifically designed for CO to control the addition of oxidant or fuel, CO being a byproduct of incomplete combustion. With N2O reduction, the examples use CO levels to achieve a trade-off between DRE and NOx production.

[0126] Although illustrative embodiments of the invention have been disclosed in detail herein with reference to the accompanying drawings, it should be understood that the invention is not limited to the precise embodiments, and that various changes and modifications may be made thereto by those skilled in the art without departing from the scope of the invention as defined by the appended claims and their equivalents.

[0127] Figure Labels

[0128] 10. Equipment for Reduction

[0129] 20. Burner with small holes

[0130] 30 Combustion chamber 30

[0131] 40 Inlet Pipe

[0132] 50 nozzles

[0133] 60 center spray gun

[0134] 70 coaxial ring

[0135] 80, 90 pressurization chambers

[0136] 100 fuel inlet

[0137] 110 Fuel / Oxidant Inlet

[0138] 120 controller

[0139] 130 Infrared Spectrometer.

Claims

1. A method for optimizing operating conditions in an orifice burner of a depletion device, the orifice burner being supplied with a hydrocarbon fuel / air mixture, the depletion device being configured to process an effluent stream including hydrogen from a semiconductor processing tool, the method comprising: The outflow stream, including hydrogen, is supplied to the orifice-filled burner via a first nozzle; Determine the concentration of carbon monoxide present in the exhaust gas of the reduction device generated by the reduction device when processing the outflow material; as well as In response to the concentration of carbon monoxide, the air supply to the second nozzle of the reduction device is adjusted, and the air is supplied to the orifice burner via the second nozzle; as well as i) Determine whether increasing the air supply will increase the concentration of carbon monoxide, and if so, reduce the air supply; or ii) Determine whether reducing the air supply will increase the concentration of carbon monoxide, and if so, increase the air supply; Until step i or ii, the concentration of carbon monoxide reaches the minimum level corresponding to the airflow region where hydrogen is completely destroyed.

2. The method according to claim 1, wherein, The determination includes measuring the concentration of the carbon monoxide using an infrared spectrometer.

3. An apparatus for optimizing / adjusting operating conditions in a reduction device, the reduction device being configured to process outflow material from a semiconductor processing tool, the apparatus comprising: A sensor configured to determine the concentration of carbon monoxide generated by the reduction device when processing the outflow stream; as well as A controller operable to adjust the operating parameters of the carbon monoxide reduction device in response to the concentration of the carbon monoxide, as described in claim 1.

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