Gas combustion apparatus

The present invention relates to an apparatus for burning a plurality of exhaust gases and a method thereof.

The main process in the manufacture of semiconductor devices is the formation of a thin film on a semiconductor substrate by a chemical reaction of a vapor precursor. One known technique for depositing thin films on a substrate is chemical vapor deposition (CVD). In this technique, the processing gas is supplied to a processing chamber containing the substrate and reacts to form a thin film over the entire surface of the substrate. For example, silane is commonly used as a silicon source and ammonia is used as a nitrogen source.

The CVD deposition method is not restricted to the surface of the substrate, resulting in, for example, clogging of gas nozzles and fogging of chamber windows. In addition, fine particles may form, which can fall onto the substrate and cause defects in the deposited thin film or interfere with the mechanical operation of the deposition system. As a result, the inner surface of the processing chamber is regularly cleaned to remove unwanted deposits from the chamber. One way to clean the processing chamber is with fluorine molecules (F)₂) And other cleaning gases are supplied to react with unnecessary sedimentary substances.

After the deposition or cleaning treatment performed in the processing chamber, the gas discharged from the processing chamber generally contains a residual amount of gas supplied to the processing chamber. Treatment gases such as silane, ammonia, and cleaning gases such as fluorine are extremely dangerous when exhausted into the atmosphere, and therefore, from this point of view, in many cases, a removal device before the exhaust gas is released into the atmosphere. Is provided to treat the exhaust gas and convert the harmful components of the exhaust gas into species that can be easily removed from the exhaust gas and / or safely discharged to the atmosphere, for example by conventional cleaning. ..

One known type of remover is described in European Patent Application No. 0819887. The removal device includes a combustion chamber having a combustion nozzle for exhaust gas to receive the exhaust gas to be processed. An annular combustion nozzle is provided on the outside of the exhaust gas nozzle, and the gas mixture of fuel and air is reduced to the inside of the combustion chamber in order to burn the exhaust gas received from the processing chamber and decompose harmful components of the exhaust gas. It is supplied to the annular combustion nozzle to form a flame.

<p> In such a device, the amount of fuel supplied to the combustion chamber is preset to be sufficient to decompose both the processing gas and the cleaning gas contained in the exhaust gas. F₂, NF₃And SF₆According to the requirements for ensuring high decomposition and removal efficiency (DRE) for fluorine-containing cleaning gases such as, the total amount of fuel is generally determined by the exothermic requirements for removing the maximum flow rate of cleaning gas entering the combustion chamber. To. Chemical vapor deposition (CVD) treatment alternates between deposition and cleaning steps at a frequency determined by the type of treatment tool. Typically, the treatment application example in which the device described in European Patent Application No. 081887 has a deposition step followed by a cleaning step. As a result, the removal device uses more fuel than is actually required to decompose the processing gas associated with deposition on the substrate to be processed for about 50% of its operating time. Operate.</p><p> Another problem faced by the use of reducing flames is high decomposition when high flow (eg, about 60 slpm (standard liter per minute)) emissions containing ammonia are received, for example, from the processing chamber of a flat panel display element. And the efficiency of removal (DRE) is not achieved.</p><p> An object of at least a preferred embodiment of the present invention is to seek solutions to these and other problems.</p>

<p> In the first aspect, the present invention provides a method of burning the exhaust gas using a plurality of exhaust gas combustion nozzles for sending the exhaust gas into the combustion chamber, and the method according to the present invention provides the respective exhaust gas. To each nozzle, the process of selectively supplying the fuel and oxidant used to form the combustion flame in the combustion chamber for each combustion nozzle, and the chemical properties of the exhaust gas sent to the combustion nozzles. It has a step of adjusting the supply of fuel and oxidant by using the fluctuation of.</p><p> This makes it possible to selectively change the properties of each combustion flame according to the properties of the received exhaust gas. This improves the efficiency of exhaust gas decomposition rates and optimizes fuel consumption. For example, the amount of fuel and oxidant supplied to the combustion nozzle is adjusted to produce an oxidative combustion flame, eg, when a first exhaust gas containing ammonia is delivered to the combustion nozzle, eg F.₂, NF₃And SF₆When a second exhaust gas containing a cleaning gas such as one of them and different from the first exhaust gas is sent to the combustion nozzle, it is adjusted to generate a reduction combustion flame.</p><p> Thus, high decomposition and removal efficiency (DRE) can be achieved in both the processing gas and the cleaning gas, and the fuel consumption of each combustion nozzle is individually optimized according to the nature of the exhaust gas delivered to that combustion nozzle. It is possible to make it. This makes it possible to minimize fuel consumption, thereby reducing operating costs and treating, for example, multiple different emissions from multiple processing chambers operating in different deposition and wash cycles. Allows a single combustion chamber to be provided for.</p><p> The adjustment of the fuel and oxidant supply to the combustion nozzle is timed according to the deposition and cleaning cycle performed in the processing chamber. As a modification, for each combustion nozzle, data indicating changes in the chemical properties of the exhaust gas sent to the combustion nozzle may be received, and the amount of fuel and oxidizer supplied to the combustion nozzle is received. Adjusted in response to data. In a preferred embodiment, each exhaust gas is discharged from the processing chamber of the processing tool and the data is supplied by the processing tool. As a variant, a gas sensor may be placed in a conduit system to deliver exhaust gas to the combustion nozzle, which gas sensor is configured to supply data.</p><p> In the second aspect, the present invention provides an apparatus for burning exhaust gas, the apparatus according to the present invention comprises a combustion chamber and a plurality of exhaust gas combustion nozzles, each of which has a combustion nozzle. It is for sending each exhaust gas into the combustion chamber, has each means for receiving the fuel and oxidant used to form the combustion flame in the combustion chamber, and further, for each exhaust gas. It has control means for receiving data indicating changes in the chemical properties of the exhaust gas and adjusting the supply of fuel and oxidant for burning the exhaust gas in response to the received data.</p><p> In a third aspect, the present invention provides a combustion apparatus, the combustion apparatus according to the present invention comprises a combustion chamber and a plurality of combustion nozzles, each of which has a combustion chamber for its own exhaust gas. It is intended to be received and sent into the combustion chamber for combustion within, and also has a plenum chamber, which is a combustion containing fuel and an oxidant to form a combustion flame within the combustion chamber. It has an inlet for receiving gas and a plurality of outlets, each of which extends around each combustion nozzle to supply combustion gas to the combustion chamber, and each of the combustion nozzles is respectively from the plenum chamber. Each means for receiving fuel and oxidant to selectively adjust the relative amount of fuel and oxidant supplied to the combustion chamber through the outlet of the combustion nozzle, and further in the combustion nozzle. It has means for selectively changing the relative amounts of the fuel and the oxidizing agent supplied to each of the above-mentioned means according to the chemical properties of the exhaust gas contained in the above-mentioned means.</p><p> The features described above for aspects of the method according to the invention are equally applicable to the aspects of the apparatus according to the invention and vice versa.</p><p> Preferred features of the present invention will be described with reference to the accompanying drawings.</p>

First referring to FIG. 1, the apparatus 10 is provided to treat gas discharged from a plurality of processing chambers 12a-12d to process, for example, a semiconductor element, a flat panel display element, or a solar panel element. ing. Although FIG. 1 shows an apparatus 10 for processing the gas discharged from the four processing chambers 12a to 12d, the apparatus 10 processes an arbitrary number, for example, 6 or 7 or more exhaust gases. Suitable for. Each of the processing chambers 12a-12d receives various processing gases (not shown) used to carry out the processing in the processing chamber. Examples of treatment gases include silane and ammonia. Exhaust gas is drawn by the respective pump system from the outlet of each processing chamber 12a-12d. Since only a portion of the processing gas is consumed during the processing in the processing chamber, the exhaust gas contains a mixture of the plurality of processing gases supplied to the processing chamber and by-products produced by the processing in the processing chamber.

In this embodiment, a deposition process is performed in each layer to deposit one or more layers of material on the surface of a substrate placed in the processing chamber. The properties of the processing gas supplied to each processing chamber may be the same or different. F to remove unwanted deposits from the processing chamber₂, NF₃, And SF₆Cleaning gas such as, etc. is periodically supplied to the processing chamber. The duration of the processing gas and cleaning gas supply cycles may be the same or different for each of the processing chambers. Since only a portion of the cleaning gas is consumed, the gas discharged from the processing chamber during the cleaning cycle contains a mixture of multiple cleaning gases supplied to the processing chamber and by-products produced by cleaning the processing chamber. .. For some treatments, it is preferable to use a remote plasma system that decomposes the cleaning gas into fluorine before it enters the processing chamber.

Exhaust gas is drawn from the outlets of the plurality of processing chambers 12a-12d by their respective pump systems 14a-14d. As shown in FIG. 1, each pump system has a secondary pump 16 typically in the form of a turbo molecular pump to draw exhaust gas from the processing chambers 12a-12d. Turbo molecular pump 16 is at least 10 in the processing chamber^-3A millibar vacuum can be created. The gas discharged from the turbo molecular pump 16 is typically about 1 mbar (10).²Pa) pressure. In this regard, the pump system also has a primary pump or backing pump 18 for receiving the gas discharged from the turbo molecular pump 16, which primary pump 18 raises the pressure of the gas to near atmospheric pressure. .. The pump systems 14a-14d may be the same or per processing chamber, depending on the nature of the processing performed within each processing chamber 12a-12d and the vacuum level required within the processing chambers 12a-12d being processed. May be changed to.

Each of the gases discharged from the pump systems 14a-14d is sent to the respective inlet 20 of the removal device 10. As shown in FIGS. 2 and 3, each inlet 20 has an exhaust gas combustion nozzle 22 connected to the combustion chamber 24 of the removal device 10. Each combustion nozzle 22 has a flanged inlet 26 and an outlet 28 for receiving the exhaust gas, and the exhaust gas enters the combustion chamber 24 from the outlet 28.

Each combustion nozzle 22 has an oxidant inlet 30 for receiving an oxidant from a source 32 (see FIG. 6) of an oxidant such as oxygen. A plurality of oxidants surrounding the combustion nozzle 22 from the oxidant inlet 30 by an annular gap 34 formed between the outer surface of the combustion nozzle 22 and the inner surface of the first sleeve 36 extending around the combustion nozzle 22. Allows to be sent to exit 38.

Each combustion nozzle 22 further has a fuel inlet 40 for receiving fuel, preferably methane, from a fuel source 42 (see FIG. 6). A plurality of annular gaps 44 formed between the outer surface of the first sleeve 36 and the inner surface of the second sleeve 46 extending around the first sleeve 36 allow fuel to surround the combustion nozzle 22 from the fuel inlet 40. Allows to be sent to fuel outlet 48.

As shown in FIGS. 2 and 4, each combustion nozzle 22 is mounted in a first annular plenum chamber 50, which is a fuel and fuel for forming a combustion flame in the combustion chamber 24. It has an inlet 52 that receives a first gas mixture of oxidants, the first gas mixture being, for example, a mixture of methane and oxygen. As shown in FIG. 2, the combustion nozzle 22 is mounted in the first plenum chamber 50 so that the oxidant outlet 38 and the fuel outlet 48 from the combustion nozzle 22 are located in the first plenum chamber 50. Therefore, the oxidant discharged from the oxidant outlet 38 and the fuel discharged from the fuel outlet 48 are locally mixed with the first gas mixture in the first plenum chamber 50. A local mixture of the fuel and oxidant formed by the first gas mixture and the fuel and oxidizer supplied to the combustion nozzle 22 is delivered from the first plenum chamber 50 through the respective outlets 54 to the combustion chamber. Entering 24, each outlet 54 is substantially coaxial with and surrounds the combustion nozzle 22.

Also, as shown in FIG. 2, the first plenum chamber 50 is located above the second annular plenum chamber 56, the second plenum chamber 56 for forming a pilot flame in the combustion chamber 24. It has an inlet 58 that receives a second gas mixture of fuel and oxidizer, the second gas mixture is, for example, another mixture of methane and oxygen. As shown in FIG. 5, the second plenum chamber 56 includes a plurality of first holes 60, a plurality of second holes 62 surrounding each of the plurality of first holes 60, and a plurality of second holes. It has a plurality of third holes 64 surrounding the hole 62, and exhaust gas from the combustion nozzle 22 enters the combustion chamber 24 through the plurality of first holes 60, and the above-mentioned local areas of fuel and oxidizer are used. Mixture enters the combustion chamber 24 from the first plenum chamber 50 through the plurality of second holes 62, the second gas mixture enters the combustion chamber 24 through the plurality of third holes 64, and the fuel and A combustion flame is formed in the combustion chamber 24 by forming a pilot flame to ignite a local mixture of oxidants.

FIG. 7 shows a control system for controlling the supply of fuel and oxidant to each of the combustion nozzles 22. The control system has a controller 70 for receiving data of a signal 72 indicating changes in the chemical properties of the exhaust gas supplied to each combustion nozzle 22, for example, at the beginning of a cleaning cycle in which the cleaning gas is supplied to the processing chamber. .. As shown in FIG. 7, it is preferable to receive each of the signals 72 directly from the respective processing tools 74a to 74d, and each processing tool 74a to 74d controls the supply of gas to the respective processing chambers 12a to 12d. Is good. As a variant, the signal 72 may be received from the host computer of the local area network, the controllers 70 and the controllers of the processing tools 74a-74d form part of the local area network, and the host computer supplies the processing chamber. It is configured to receive information about the chemical properties of the gas to be produced from the controller of the processing tool and to output a signal 72 to the controller 70 in response. As another variant, the signal 72 may be received from a plurality of gas sensors, each gas sensor being located between the outlet of each processing chamber and each combustion nozzle 22.

The controller 70 may selectively control the relative amounts of fuel and oxidant supplied to each combustion nozzle 22 in response to the data contained in the received signal 72. Referring to FIGS. 6 and 7, the control system includes a first plurality of variable flow rate control devices 76 and a second plurality of variable flow rate control devices 80, each of which is a first variable flow rate control device 76. The second variable flow control device 80 is arranged between the oxidant supply source 32 and each oxidant inlet 30, respectively, and is arranged between the fuel supply source 42 and each fuel inlet 40. For example, the variable flow control devices 76, 80 are butterfly valves or other control valves having conductance that can preferably be changed in proportion to the received signals 78, 82 from the controller 70. As a variant, a fixed orifice flow control device may be used to control the flow rate of fuel and / or oxidizer into the combustion nozzle 22. Therefore, the controller 70 controls the flow rate of the oxidant to the selected combustion nozzle 22 by the first variable flow rate in order to change the amount of the oxidant supplied to the selected one of the combustion nozzles 22. A signal 78 to be changed by the device 76 is selectively output to a suitable first variable flow control device 76 and is selected to change the amount of fuel supplied to the selected combustion nozzle 22. A signal 82 for changing the flow rate of fuel to the combustion nozzle 22 by the second variable flow rate control device 80 is selectively output to an appropriate second variable flow rate control device 80.

The controller 70 selectively selects each combustion flame generated in the combustion chamber 24 according to the chemistry of the exhaust gas by changing the relative amount of fuel and oxidizer supplied to each combustion nozzle 22. It is better to change to. For example, the relative amounts of fuel and oxidant supplied to the combustion nozzle 22 are adjusted to produce an oxidative combustion flame when the exhaust gas contains ammonia, and the exhaust gas is F.₂, NF₃Or SF₆When it contains cleaning gas, it should be adjusted to produce a reduction combustion flame.

It is preferable to change the nature of the combustion flame by increasing the relative amounts of only one of the fuel and the oxidizer. For example, the controller 70 is often configured such that the minimum amount of fuel and oxidant to be supplied to each combustion nozzle is preset with a relative amount of one selected of fuel and oxidant. The relative amount is such that by activating a selected one of the variable flow control devices 76, 80 as needed at each combustion nozzle 22 so as to alter the nature of the combustion flame. It can be selectively increased.

Returning to FIG. 1, the by-products produced by the combustion of the exhaust gas in the combustion chamber 24 are sent to a wet scrubber, solid reaction medium or other secondary removal device 90, as shown in FIG. Is good. The exhaust gas stream is safely released into the atmosphere after passing through the removal device 90.

In summary, a device for burning exhaust gases from multiple processing chambers has been described. The device has a plurality of exhaust gas combustion nozzles connected to the combustion chamber. Each combustion nozzle has means of receiving its own exhaust gas and the fuel and oxidizer used to form the combustion flame in the processing chamber. The controller receives data indicating the chemical properties of the exhaust gas supplied to each combustion nozzle and adjusts the relative amount of fuel and oxidizer supplied to each combustion nozzle in response to the received data. To do. This makes it possible to selectively change the properties of each combustion flame according to the properties of the exhaust gas to be decomposed by the combustion flame, thereby improving the decomposition rate efficiency of the exhaust gas and fuel consumption. Optimize.

The ability to adjust the flame conditions at each combustion nozzle also ensures that sufficient fuel is available to act as both a heat source and a chemical reagent in the removal of fluorine and fluorine-containing gases. This is essential for maximizing the removal efficiency achieved by the removal device while reducing fuel consumption.

In the preferred embodiment described above, although a single combustion nozzle is used to deliver the exhaust gas from the processing chamber to the combustion chamber, the exhaust gas is branched into two or more streams, each stream. May be sent to each combustion nozzle. It has been found that this further increases the efficiency with which the exhaust gas is decomposed.

<figref num="1">It is a figure which shows a plurality of processing chambers connected to a combustion apparatus.</figref><figref num="2">It is sectional drawing of a plurality of exhaust gas combustion nozzles connected to the combustion chamber of a combustion apparatus.</figref><figref num="3">It is a perspective view of a combustion nozzle.</figref><figref num="4">FIG. 5 is a perspective view of a plurality of combustion nozzles arranged in a first plenum that receives a first gas mixture for forming a combustion flame in a combustion chamber.</figref><figref num="5">It is a perspective view from the rear of the second plenum which receives the second gas mixture for forming a pilot flame in a combustion chamber.</figref><figref num="6">It is a figure which shows the structure for supplying a fuel and an oxidant to each combustion nozzle connected to a combustion chamber.</figref><figref num="7">It is a figure which shows the control system for controlling the relative amount of a fuel and an oxidant supplied to each combustion nozzle.</figref>