KR102315105B1 - Process gas abatement - Google Patents

Abstract

The present invention discloses a process gas abatement apparatus and method. The process gas abatement apparatus includes a burner, the burner operable to receive an effluent gas stream from the manufacturing process tool and to be treated in the combustion chamber under negative pressure, and also operable to receive fuel, an oxidant and a diluent. wherein the fuel, oxidant and diluent control combustion in the combustion chamber to treat the effluent gas stream to produce a treated exhaust stream, and wherein the diluent condenses in the treated exhaust stream. can be For example, by providing the diluent in the form of an inert condensable material, the volume increase within the combustion chamber is reduced, which reduces the volume of the exhaust stream and reduces the volumetric load on the second pump. The volume increase is reduced because the diluent effectively removes the diluent's contribution to the volume of the exhaust stream by moving the phase within the exhaust stream. This leads to significant power savings as a smaller volume of gas is withdrawn from the combustion chamber which needs to be raised by a second pump to a second pressure, eg atmospheric pressure.

Description

Process gas reduction {PROCESS GAS ABATEMENT}

The present invention relates to a process gas abatement apparatus and method.

Apparatus for treating an effluent gas stream from a manufacturing process tool operating at sub-atmospheric pressure, for example used in the semiconductor or flat panel display manufacturing industry, is known. During this manufacturing process, residual perfluorinated compounds (PFCs) and other compounds are present in the effluent gas stream pumped from the process tool. PFCs are difficult to reduce or remove from effluent gases, and their release into the environment is undesirable because they are known to have relatively high greenhouse activity.

One way to reduce the effluent gas is to pump the effluent gas to a higher negative pressure in the process tool before it is fed to a radiant burner. Radiant burners use combustion to remove PFCs and other compounds from the process gas stream. Typically, the effluent gas stream is a nitrogen stream containing PFCs and other compounds. The fuel gas is mixed with an effluent gas stream, and the gas stream mixture is conveyed into a combustion chamber laterally surrounded by an exit surface of a foraminous gas burner. Fuel gas and air are simultaneously fed to the perforated burner to cause flameless combustion at the outlet surface, where the amount of air passing through the perforated burner is the same as the fuel gas supplied to the burner as well as the gas stream mixture injected into the combustion chamber. Enough to consume all combustible materials. The resulting treated gas stream is exhausted from the radiant burner. The treated gas stream is then pumped to atmospheric pressure before being discharged.

Techniques exist for treating effluent gas streams, but such techniques have their own drawbacks. Accordingly, it would be desirable to provide an improved technique for treating an effluent gas stream.

According to a first aspect, there is provided a process gas abatement apparatus comprising a burner, the burner operable to receive an effluent gas stream from a manufacturing process tool and to be treated in a combustion chamber under negative pressure, and further comprising a fuel, an oxidant and a combustion chamber operable to receive a diluent, wherein the fuel, oxidant and diluent control combustion within the combustion chamber to process the effluent gas stream to produce a treated exhaust stream, the diluent comprising: It may be condensed in the treated exhaust stream.

The first aspect recognizes that, as noted above, with existing approaches, the burner can be operated at a pressure between the pressure of the process tool but below atmospheric pressure. For example, the burner is typically operated at approximately 200 mbar, the process gas is brought to this pressure by means of a multi-stage dry pumping mechanism, and the combustion by-products are transferred to a second pump by a second pump, for example a liquid ring pump. pressure, for example atmospheric pressure.

Typically, hydrocarbon fuels provide the energy source for combustive abatement in the combustion chamber, and sometimes this fuel is methane. It combusts process gas (P) according to the following reaction equation (1) to produce treated process gas (P'):

10P + CH ₄ + 2O ₂ = CO ₂ + 2H ₂ O + 10P' (1)

Assuming that atmospheric combustion characteristics also result in negative pressure combustion, each standard liter per minute (slm) of methane can reduce process exhaust by about 10 standard liters per minute. As with CH ₄ and pure oxygen, the increase in volume between the volume of gas entering the combustion chamber and the volume of gas exiting the combustion chamber is only 10% (ie 10 slm of process exhaust gas is introduced into the combustion chamber, 11 slm is discharged from the combustion chamber).

However, typically, O ₂ will be delivered as 20.9% by volume in air, thus entraining a _{significant volume of N 2 .} Using air is a convenient source of _{O 2 , and N 2} is also useful in the combustion chamber because it helps control the flame speed and temperature within the combustion chamber.

If air is used, it burns according to the following reaction equation:

10P + CH ₄ + 2O ₂ + 8N ₂ = CO ₂ + 8N ₂ + 2H ₂ O + 10P' (2)

However, the first aspect is that the increase in volume between the volume of gas entering the combustion chamber and the volume of gas exiting the combustion chamber is almost doubled (ie, 10 slm of process exhaust gas is introduced into the combustion chamber, and 19 slm is burned discharged from the chamber).

Accordingly, a process gas abatement apparatus can be provided. Such a device may include a burner. The burner may include a combustion chamber that receives a process gas or an effluent gas stream from a manufacturing process tool. The effluent gas stream may be treated at negative pressure in the combustion chamber. The combustion chamber may contain fuel, an oxidant and a diluent. The fuel, oxidant and diluent may control combustion within the combustion chamber to treat the effluent gas stream and produce a treated exhaust stream. The diluent may condense in the treated exhaust stream.

_{A first aspect recognizes that the purpose of the N 2} provided in the existing process is to control the flame speed and temperature within the combustion chamber, and therefore only use _{N 2 for convenience, since N 2} is normally present in air. . If this N ₂ could be replaced, for example, by a diluent in the form of an inert condensable material, the volume increase in the combustion chamber would be reduced, which would reduce the volume of the exhaust stream and the volume load on the second pump. will reduce The volume increase is reduced because the diluent effectively removes the diluent's contribution to the volume of the exhaust stream by moving the phase within the exhaust stream. This leads to significant power savings as a smaller volume of gas is withdrawn from the combustion chamber which needs to be raised to a second pressure, eg atmospheric pressure, by means of a second pump.

In one embodiment, the diluent comprises vapor when introduced into the combustion chamber. Thus, the diluent may be mixed in vapor form with the fuel and oxidant to effect combustion with the properties required to treat the effluent gas stream. For example, the transition of an inert condensable vapor to a liquid in the exhaust gas stream also during volume reduction because the diluent effectively removes the diluent's contribution to the volume of the exhaust stream by moving a phase within the exhaust gas stream. Diluents can all contribute to the characteristics of combustion.

In one embodiment, the diluent comprises a liquid prior to being vaporized for introduction into the combustion chamber. It will be appreciated that this greatly simplifies the storage of the diluent.

In one embodiment, the diluent condenses to a liquid in the treated exhaust gas stream. It will be appreciated that the phase change from vapor to liquid causes a significant decrease in volume.

In one embodiment, the diluent is introduced into the combustion chamber at a first volumetric rate and occupies the treated exhaust stream at a second volumetric rate lower than the first volumetric rate.

In one embodiment, the diluent is provided in a specified volume fraction to control combustion conditions within the combustion chamber for treating the effluent gas stream.

In one embodiment, the diluent is combined with at least one of the fuel and the oxidant prior to introduction into the combustion chamber. It will be appreciated that this greatly simplifies the storage of diluents and/or fuels and oxidants.

In one embodiment, at least one of the fuel and the oxidant is dissolved by the diluent prior to introduction into the combustion chamber.

In one embodiment, both the fuel and the oxidant are dissolved by the diluent prior to introduction into the combustion chamber.

In one embodiment, at least one of the fuel dissolved by the diluent and the oxidant is vaporized prior to introduction into the combustion chamber.

In one embodiment, the diluent and at least one of fuel and oxidant dissolved by the diluent are co-vaporized prior to introduction into the combustion chamber.

In one embodiment, the diluent comprises at least one of water, a perfluorocarbon, and a hydrocarbon.

In one embodiment, the burner comprises a radiant burner and the combustion chamber has a porous sleeve through which fuel, oxidant and diluent pass for combustion at a location proximate to the combustion surface of the porous sleeve.

In one embodiment, the treated exhaust stream is provided to a liquid ring pump for compression to atmospheric pressure.

In one embodiment, the diluent condenses in a liquid ring pump. Thus, the liquid ring pump can also act as an efficient condenser.

In one embodiment, the liquid ring pump is operable to scrub the treated exhaust stream. Thus, the liquid ring pump can also act as an efficient scrubber.

According to a second aspect of the present invention, there is provided a method comprising: receiving an effluent gas stream to be treated from a manufacturing process tool in a combustion chamber under negative pressure; receiving a fuel, oxidant and diluent into a combustion chamber, wherein the fuel, oxidant and diluent control combustion within the combustion chamber to process the effluent gas stream to produce a treated exhaust stream; and condensing the diluent in the treated exhaust stream.

In one embodiment, the receiving step comprises introducing the diluent as a vapor into the combustion chamber.

In one embodiment, the diluent comprises a liquid prior to being vaporized for introduction into the combustion chamber.

In one embodiment, the condensing step comprises condensing the diluent to a liquid in the treated exhaust stream.

In one embodiment, the receiving step comprises introducing a diluent into the combustion chamber at a first volumetric rate and the condensing step comprising occupying the treated exhaust stream at a second volumetric rate, wherein the second volume The ratio is lower than the first volume ratio.

In one embodiment, the receiving step includes providing a diluent at a specified volume rate to control the combustion conditions within the combustion chamber to treat the effluent gas stream.

In one embodiment, the method comprises combining the diluent with at least one of a fuel and an oxidant prior to introduction into the combustion chamber.

In one embodiment, the method comprises dissolving at least one of the fuel and the oxidant with a diluent prior to introduction into the combustion chamber.

In one embodiment, the method comprises dissolving both the fuel and the oxidant with a diluent prior to introduction into the combustion chamber.

In one embodiment, the receiving step comprises vaporizing at least one of the fuel and the oxidant dissolved by the diluent prior to introduction into the combustion chamber.

In one embodiment, the receiving step comprises co-vaporizing the diluent and at least one of the fuel and the oxidant dissolved by the diluent prior to introduction into the combustion chamber.

In one embodiment, the diluent comprises at least one of water, a perfluorocarbon, and a hydrocarbon.

In one embodiment, the burner comprises a radiant burner and the combustion chamber has a porous sleeve through which fuel, oxidant and diluent pass for combustion at a location proximate to the combustion surface of the porous sleeve.

In one embodiment, the method comprises providing the treated exhaust stream to a liquid ring pump for compression to atmospheric pressure.

In one embodiment, the condensing step comprises condensing the diluent in a liquid ring pump.

In one embodiment, the method comprises scrubbing the treated exhaust stream using a liquid ring pump.

Further specific and preferred embodiments are set forth in the independent and dependent claims of the appended claims. Features of the dependent claims may be combined with features of the independent claims as the case may and in combinations other than those expressly stated in the claims.

Where a device feature is described as being operable to provide a particular function, it will be appreciated that it includes a device feature that provides, or is adapted or configured to provide, such a function.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be further described with reference to the accompanying drawings:
1 illustrates a process gas abatement apparatus according to one embodiment.

summary

Before discussing embodiments in more detail, an overview will first be provided. In an embodiment, the negative pressure combustion system is operated with a diluent that condenses in its exhaust stream to reduce the volume of exhaust gas emitted. This reduces the volume of exhaust gas that needs to be compressed to atmospheric pressure before being discharged to the atmosphere.

process gas reduction

1 illustrates a process gas abatement apparatus 100 according to one embodiment. The first pump stage 10 evacuates a process chamber, such as a semiconductor process chamber, and absorbs a process gas or effluent gas stream P provided at a first pressure such as 1 mbar to produce an effluent gas stream P is compressed to an intermediate pressure such as 100 to 200 mbar. The first pump stage 10 typically comprises a dry pump.

Radiant burner 20 or other combustion device receives the effluent gas stream P at medium pressure. Radiant burner 20 also contains a fuel/oxidizer mixture in addition to the diluent (D). An effluent gas stream P is provided into a combustion chamber laterally surrounded by an outlet surface of the foraminous gas burner. The fuel/oxidizer mixture is fed simultaneously with the diluent (D) to the perforated burner to cause a salt-free combustion at the outlet surface. The amount of oxidant passing through the perforated burner is sufficient to consume not only the fuel supplied to the burner, but also all combustible materials in the effluent gas stream injected into the combustion chamber. The diluent (D) is provided in an amount sufficient to control the flame speed at the exit surface of the perforated burner and to control the temperature and other combustion characteristics within the combustion chamber. The treated effluent gas stream P' is exhausted from the radiant burner along with other by-products of combustion in the combustion chamber. The diluent (D) is condensed in the treated effluent gas stream.

The treated effluent gas stream P' compresses the treated effluent gas stream P' together with other by-products of combustion in the combustion chamber to a second pressure, such as atmospheric pressure, before being discharged to the atmosphere. An auxiliary pump stage 30 such as a pump is provided.

Example work

In this embodiment, the effluent gas stream P is provided from the first pump stage 10 to the radiant burner 20 at a rate of 10 standard liters per minute (slm). In order to treat the effluent gas stream P, the fuel/oxidant mixture is suitably adjusted for flame speed, temperature and other combustion characteristics within the combustion chamber according to the following reaction equation (3) for accurately treating the effluent gas stream P. It is given at a rate of 3 slm with a diluent data rate of 8 slm to control:

10P + CH ₄ + 2O ₂ + 8D(g) = CO ₂ + 8D(l) + 2H ₂ O + 10P' (3)

For example, such radiant burners 20 operating at approximately 200 mbar are fueled with hydrocarbons, such as methane, and oxygen. It is diluted with an appropriate concentration of diluent (D).

As the diluent (D) condenses in the effluent gas stream (P'), it is typically liquid under ambient conditions and is therefore heated to vaporize before being fed to the combustion chamber. Accordingly, the liquid diluent (D) may be mixed with the fuel and/or the oxidant for storage in a convenient manner prior to introduction into the combustion chamber.

diluent

In one example, the diluent (D) is conveniently water. A further advantage of supplying a significant amount of water vapor at the flame temperature in the combustion chamber is that it provides an attendant reagent for the reduction _{of F 2 in the effluent gas stream P according to equation (4):}

F ₂ + H ₂ O = 2HF + ½O ₂ (4)

Excess O _{2 generated} Also it is, for example, SiH ₄ This is helpful because it reacts with a deposition gas such as

The fuel can be dissolved in water for convenient storage. For example, alcohol can be dissolved in water to provide an aqueous solution, which can then be vaporized before being introduced into the combustion chamber. Likewise, the oxidizing agent may be dissolved in water for convenient storage. For example, hydrogen peroxide can be dissolved in water to provide an aqueous solution, which can then be vaporized before being introduced into the combustion chamber. Similarly, both fuel and oxidant can be dissolved in water for convenient storage. If it is derived from a 70°C/300 mbar source, it requires approximately 2600 J/g to produce it. The power to do this is roughly:

(8/22.4) × 18 × 2600/60 = 280 Watts (W)

This power can be derived from waste heat generated in the vacuum pump. In an integrated system, the water (and pump) may be electrically preheated and the temperature maintained by an equilibrium between evaporation and exotherm.

Considering the above example when the process gas P to be treated is about 10 slm, typically about 1 slm of CH ₄ and 2 slm of O ₂ would be required. To dilute this and provide combustion properties similar to those achieved using air, about 8 slm of H ₂ O would also be required as diluent (D).

As water condenses in the treated effluent gas stream, about 10 slm of the treated effluent gas stream (P') is provided along with _{1 slm of CO 2 .} This means that rather than 19 slm being provided to the auxiliary pump stage 30, only 11 slm is provided, which significantly reduces the amount to be compressed and reduces the power consumption to achieve this.

The auxiliary pump stage 30 may be a liquid ring pump. It would be particularly advantageous to provide a liquid ring pump because the liquid ring pump both assists in the condensation of the diluent and can be used to scrub a given gas stream.

Although the above examples use water as the diluent, it will be appreciated that the diluent may be any suitable compound that condenses in the effluent gas stream, such as, for example, perfluorocarbons or hydrocarbons.

While exemplary embodiments of the present invention have been disclosed in detail herein with reference to the accompanying drawings, the invention is not limited thereto, but the invention as defined by the appended claims and their equivalents. It should be understood that various changes and modifications may be practiced herein by those skilled in the art without departing from the scope thereof.

Claims (15)

A process gas abatement device comprising a burner, comprising:
the burner comprises a combustion chamber;
The combustion chamber is operable to receive an effluent gas stream from a manufacturing process tool and to be treated in the combustion chamber under sub-atmospheric pressure, and to receive fuel, an oxidant and a condensable diluent. can work,
wherein the fuel, oxidant and condensable diluent control combustion within the combustion chamber to treat the effluent gas stream to produce a treated exhaust stream;
wherein the diluent is condensable in the treated exhaust stream.
Process gas abatement devices. The method of claim 1,
and the diluent comprises vapor when introduced into the combustion chamber. The method of claim 1,
and the diluent comprises a liquid prior to being vaporized for introduction into the combustion chamber. The method of claim 1,
wherein the diluent condenses to a liquid in the treated exhaust stream. The method of claim 1,
wherein the diluent is introduced into the combustion chamber at a first volumetric rate and occupies the treated exhaust stream at a second volumetric rate lower than the first volumetric rate. The method of claim 1,
and the diluent is introduced into the combustion chamber after being combined with at least one of the fuel and the oxidant. 7. The method of claim 6,
wherein at least one of the fuel and the oxidant is introduced into the combustion chamber after being dissolved by the diluent. 7. The method of claim 6,
wherein both the fuel and the oxidant are introduced into the combustion chamber after being dissolved by the diluent. 8. The method of claim 7,
wherein at least one of the fuel and the oxidant dissolved by the diluent is vaporized prior to introduction into the combustion chamber. 8. The method of claim 7,
at least one of the fuel and oxidant dissolved by the diluent and the diluent are co-vaporised prior to introduction into the combustion chamber. The method of claim 1,
wherein the diluent comprises at least one of water, perfluorocarbons and hydrocarbons. 12. The method according to any one of claims 1 to 11,
wherein the treated exhaust stream is fed to a liquid ring pump for compression to atmospheric pressure. 13. The method of claim 12,
and the diluent is condensed in the liquid ring pump. 13. The method of claim 12,
and the liquid ring pump is operable to scrub the treated exhaust stream. receiving the effluent gas stream to be treated from the manufacturing process tool into a combustion chamber under a negative pressure;
receiving a fuel, an oxidant and a condensable diluent within the combustion chamber, wherein the fuel, oxidant and condensable diluent are disposed within the combustion chamber to treat the effluent gas stream to produce a treated exhaust stream. controlling combustion; and
condensing the diluent in the treated exhaust stream.
Including, process gas reduction method.

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