Whirlwind-type oxidation combustion apparatus for processing semiconductor fabrication exhaust gas

A whirlwind-type oxidation combustion apparatus for processing semiconductor fabrication exhaust gas is disclosed. An inlet head is set on the top of an exhaust gas processing tank. An exhaust gas passage is set inside the inlet head and connected to an external exhaust gas supply terminal and the exhaust gas processing tank, for guiding the exhaust gas into the exhaust gas processing tank. An ignition chamber is formed between two partitions outside the exhaust gas passage. The two partitions have multiple inclined holes interconnecting an external combustion gas supply terminal, the ignition chamber, and the exhaust gas processing tank. The inclined holes guide a combustion gas to swirl into the exhaust gas processing tank through the ignition chamber. An igniter in the ignition chamber ignites the combustion gas to form a vortex flame which burns the exhaust gas. The exhaust gas is further caused to swirl onto a water screen.

BACKGROUND

1. Technical Field

The present invention relates to a whirlwind-type oxidation combustion apparatus for processing semiconductor fabrication exhaust gas. More particularly, the present invention relates to an inlet head for processing semiconductor fabrication exhaust gas, wherein inside the inlet there are an exhaust gas passage, an ignition chamber, and inclined holes for guiding the exhaust gas.

2. Related Art

The semiconductor fabrication process will generate exhaust gases that are toxic, erosive, and inflammable. To prevent the exhaust gases from causing environment pollution, the exhaust gases can be discharged to the atmosphere only after the toxic objects in the exhaust gases have been filtered out.

In a conventional method of processing semiconductor fabrication exhaust gas, the exhaust gas is firstly injected into an exhaust gas processing tank. The high temperature flame in the exhaust gas processing tank will burn the exhaust gas to produce a high temperature exhaust gas, causing the toxic objects in the high temperature exhaust gas to be catalyzed by the high temperature and to decompose into harmless objects. Then, wash water inside the exhaust gas processing tank will dissolve the dissolvable toxic objects in the high temperature exhaust gas and hence convert the high temperature exhaust gas into a harmless and cooled gas. Then, the cooled harmless gas can be discharged to the atmosphere without causing environment pollution.

Generally, on the top of a conventional exhaust gas processing tank there is an inlet head that allows an exhaust gas and an oxygen-containing combustion gas to be injected. The exhaust gas and the oxygen-containing combustion gas will be mixed up, and the oxygen-containing combustion gas will be ignited to produce high temperature flame to burn the exhaust gas.

Currently, there are some commercially-applied methods of processing semiconductor fabrication exhaust gas using high temperature flame and wash water as discussed above. Examples of such methods include Taiwan Patents No. 482038 and No. 570146. They use the inlet head on the top of the exhaust gas processing tank to produce high temperature flame to pre-burn the exhaust gas injected from an external exhaust gas supply terminal into the inlet head. They then spray or overflow wash water to produce a water screen inside the exhaust gas processing tank underneath the inlet head to dissolve toxic objects within the exhaust gas.

However, according to the two Taiwan Patents, the exhaust gas has a direct path through the inlet head and the exhaust gas processing tank. In other words, the exhaust gas has a direct path through the high temperature flame and the wash water. This inevitably limits the interaction time between the exhaust gas and the high temperature flame and the wash water. Without enough interaction time, the toxic objects might not be fully burned by the high temperature flame and fully dissolved in the wash water. This is a drawback that needs to be resolved.

BRIEF SUMMARY

One of the objectives of the present invention is to overcome the problem of the related art, in which the semiconductor fabrication exhaust gas has a direct path through the high temperature flame and the wash water and hence has limited interaction time with the high temperature flame and the wash water.

According to the present invention, the whirlwind-type oxidation combustion apparatus for processing semiconductor fabrication exhaust gas has an inlet head set in between an exhaust gas supply terminal and a combustion gas supply terminal. The inlet head locates on the top of an exhaust gas processing tank. An outer water screen is formed on the inner wall of the exhaust gas processing tank. The inlet head includes an exhaust gas passage, an upper partition and a lower partition, a plurality of upper inclined holes, an igniter, and a plurality of lower inclined holes.

The exhaust gas passage is connected in between the exhaust gas supply terminal and the exhaust gas processing tank, for guiding the exhaust gas down into the exhaust gas processing tank.

The upper partition and the lower partition lie in between the surrounding of the exhaust gas passage and the inner wall of the inlet head. An ignition chamber is formed in between the surrounding of the exhaust gas passage, the inner wall of the inlet head, and the upper and lower partitions.

The upper inclined holes scatter in a vortex pattern on the upper partition and encircle the surrounding of the exhaust gas passage. The upper inclined holes interconnect the combustion gas supply terminal and the ignition chamber, for guiding the combustion gas to swirl down into the ignition chamber.

The igniter is planted in the ignition chamber, for igniting the combustion gas in the ignition chamber to form a vortex flame to heat up the exhaust gas in the exhaust gas passage.

The lower inclined holes scatter in a vortex pattern on the lower partition and encircle the surrounding the exhaust gas passage. The lower inclined holes interconnect the ignition chamber and the exhaust gas processing tank. The lower inclined holes guides the flame to swirl into the exhaust gas processing tank, combusting the exhaust gas entered from the exhaust gas passage into the exhaust gas processing tank, causing toxic objects in the exhaust gas to be catalyzed by high temperature and decompose into harmless objects. The flam further leads the exhaust gas to swirl onto a water screen, causing the toxic objects in the exhaust gas to dissolve into the water screen. As a result, the exhaust gas will be cooled and become a harmless gas.

Because the upper and lower inclined holes have the same swirling direction, after the combustion gas that swirls into the ignition chamber through the upper inclined holes is ignited and becomes the flame, the combustion gas will swirl into the exhaust gas processing tank through the lower inclined holes and forms a flame that swirls down. This will cause the exhaust gas in the exhaust gas processing tank to swirl downwards. Accordingly, the vortex flame will cause the semiconductor fabrication exhaust gas to swirl down and pass through the high temperature flame (which is swirling) and wash water. This gives the exhaust gas more time to interact with the swirling flame and the wash water. This increases the efficiency of the flame in eliminating the harmful objects in the exhaust gas. Furthermore, the water screen has more time to dissolve the harmful objects in the exhaust gas and prevents the inner wall of the exhaust gas processing tank from dirt accumulation and erosion.

In addition, the present invention further discloses the followings:

A combustion gas chamber is formed between the surrounding of the exhaust gas passage, the top of the upper partition, and the inner wall of the inlet head. The combustion gas chamber interconnects the combustion gas supply terminal and the upper inclined holes so that the combustion gas is evenly provided to the upper inclined holes.

The combustion gas chamber has a container pipe that is connected to the ignition chamber. The igniter is set inside the container pipe. The container pipe has a plurality of air vents that interconnect the interior of the container pipe and the combustion gas chamber, for guiding the combustion gas into the container pipe to be ignited by the igniter and become a pilot light.

On a corresponding end beneath the exhaust gas passage and the lower inclined holes there is a combustion chamber sink. The combustion chamber sink interconnects the exhaust gas passage and the lower inclined holes. The bottom of the combustion chamber sink has a sink opening that is connected to the exhaust gas processing tank.

An annular upper sink is formed between the surrounding of the ignition chamber and the inner wall of the inlet head, for guiding in external wash water. An upper overflow opening is connected between the upper sink and the interior of the exhaust gas processing tank, for guiding the wash water to overflow into the exhaust gas processing tank to form an inner water screen on the inner side of the outer water screen. The inner water screen is to be blown by the exhaust gas and will dissolve toxic objects in the exhaust gas.

An annular collecting trough is formed between the surrounding of the ignition chamber and the inner wall of the inlet head. The annular collecting trough is connected to the upper sink and locates on the top of the upper sink. The external wash water is guided into the upper sink through the collecting trough.

An annular lower sink is formed on the inner wall of the exhaust gas processing tank for guiding in external wash water. A lower overflow opening interconnects the lower sink and the interior of the exhaust gas processing tank. The lower overflow opening guides the wash water to overflow into the exhaust gas processing tank to form the outer water screen.

DETAILED DESCRIPTION

FIG. 1andFIG. 2are cross-sectional diagrams of a whirlwind-type oxidation combustion apparatus according to an embodiment of the present invention. The apparatus is used to process a semiconductor fabrication exhaust gas. According to the embodiment, an inlet head3is set in between a semiconductor fabrication exhaust gas supply terminal11and a combustion gas supply terminal12. The inlet head3lies on the top of an exhaust gas processing tank2. An outer water screen81is formed on the inner wall of the exhaust gas processing tank2(as shown inFIG. 7). The inlet head3contains a vertical exhaust gas passage4, an upper partition5, a lower partition6, a plurality of upper inclined holes51, an igniter7, and a plurality of lower inclined holes61. The combustion gas supply terminal12supplies a combustion gas that contains 5%˜15% of natural gas and 95%˜85% of air. A conventional Venturi tube pre-mixer, which locates externally, can pre-mix the natural gas and external air to form the oxygen-contained combustion gas. This avoids the necessity of providing oxygen alone. The exhaust gas processing tank2has a reaction chamber20in its center. The inner wall of the exhaust gas processing tank2forms a lower sink21that is annular in shape. The outer wall of the exhaust gas processing tank2has a second water inlet22that is connected to the lower sink21. To supply wash water to the lower sink21, the second water inlet22can be connected with an outer wash water supply terminal13. A lower overflow opening23, which is annular in shape, interconnects the top of the lower sink21and the reaction chamber20inside the exhaust gas processing tank2. The wash water in the lower sink21can be guided by the lower overflow opening23to overflow into the reaction chamber20of the exhaust gas processing tank2, and flow down along the inner wall of the reaction chamber20to form an outer water screen81.

As shown inFIG. 1andFIG. 3, the exhaust gas passage4is formed inside a circular duct40, which has a vertical arrangement and is in the center of the inlet head3. The exhaust gas passage4further forms an exhaust gas inlet41that is on the top of the inlet head3and is connected to the exhaust gas supply terminal11. The exhaust gas passage4also forms an exhaust gas outlet42that is on the bottom of the inlet head3and is connected to the reaction chamber20of the exhaust gas processing tank2, so that the exhaust gas passage4is connected between the exhaust gas supply terminal11and the reaction chamber20of the exhaust gas processing tank2and hence can guide the exhaust gas to flow downwards into the reaction chamber20of the exhaust gas processing tank2. Both the upper partition5and the lower partition6have annular shapes, as shown inFIG. 6; they encircle the outer wall of the duct40(seeFIG. 4andFIG. 5for more details) and lie between the surrounding of the duct40(that encompasses the exhaust gas passage4) and the inner wall of the inlet head3. The lower partition6is beneath the upper partition5, and outside the duct40of the exhaust gas passage4. An ignition chamber32is formed between the surrounding of the duct40(which contains the exhaust gas passage4), the inner wall of the inlet head3, and the upper and lower partitions5and6.

As shown inFIG. 2andFIG. 3, the upper inclined holes51scatter (in a vortex pattern) on the upper partition5, and surrounds the duct40, which encompasses the exhaust gas passage4(seeFIG. 3aandFIG. 6for more detail). A combustion gas chamber31is formed between the inner wall of the inlet head3, the surrounding of the duct40(which encompasses the exhaust gas passage4), and the top of the upper partition5, and is connected to the tops of the upper inclined holes51. The outer wall of the inlet head3has a combustion gas inlet311that is connected to the combustion gas chamber31and the combustion gas supply terminal12. The bottoms of the upper inclined holes51are connected to the ignition chamber32, so that the upper inclined holes51interconnect the combustion gas supply terminal12and the ignition chamber32. The combustion gas supply terminal12supplies a combustion gas, which contains oxygen, to the combustion gas chamber31of the inlet head3. The combustion gas chamber31equally supplies the combustion gas to each of the upper inclined holes51. The upper inclined holes51can guide the combustion gas in the combustion gas chamber31to swirl downwards into the ignition chamber32, so that the combustion gas can swirl downwards within the ignition chamber32. Inside the combustion gas chamber31there is a container pipe33that is connected to the ignition chamber32. The igniter7is planted inside the container pipe33, and extends into the ignition chamber32. The container pipe33has a plurality of air vents331; they connect the interior of the container pipe33and the combustion gas chamber31. They guide the combustion gas in the combustion gas chamber31into the container pipe33, which will then be ignited by the igniter7and becomes a pilot light flame91(as shown inFIG. 7). The pilot light flame91ignites the combustion gas in the ignition chamber32to form a flame92that swirls downwards, passes through the outer wall of the duct40, and heats up the exhaust gas in the exhaust gas passage4.

The lower inclined holes61scatter (in a vortex pattern) on the lower partition6(as shown inFIG. 2andFIG. 4) and surround the duct40, which encompasses the exhaust gas passage4(seeFIG. 4aandFIG. 6for more detail). The upper and lower inclined holes51and61have the same vortex direction. The lower inclined holes61interconnects the ignition chamber32and the reaction chamber20of the exhaust gas processing tank2; it can guide the flame92in the ignition chamber32to swirl downwards into the reaction chamber20of the exhaust gas processing tank2. The flame92will keep swirling in the reaction chamber20downwards. Around the bottom of the inlet head3there is a ring sheath34extending downwards into the exhaust gas processing tank2. The interior of the ring sheath34has a combustion chamber sink341located on a corresponding end beneath the exhaust gas passage4and the lower inclined holes61. The combustion chamber sink341interconnects the exhaust gas passage4and the lower inclined holes61. The bottom of the combustion chamber sink341has a sink opening342that is connected to the reaction chamber20of the exhaust gas processing tank2. The lower overflow opening23can be formed between the top of the lower sink21and the outer wall of the ring sheath34.

Between the surrounding of the ignition chamber32and the inner wall of the inlet head3there is an upper sink35(as shown inFIG. 1) that is annular in shape and a collecting trough36(seeFIG. 3) that is also annular in shape. The collecting trough36is on the top of the upper sink35. A plurality of drainage holes361interconnect the collecting trough36and the upper sink35. The outer wall of the inlet head3has a first water inlet362that interconnects the collecting trough36and the external wash water supply terminal13. Therefore wash water can be supplied into the upper sink35from the collecting trough36and the holes361. An upper overflow opening351, which is annular in shape, interconnects the top of the upper sink35and the combustion chamber sink341inside the exhaust gas processing tank2. Therefore, the wash water inside the upper sink35can be guided to overflow to the inner wall of the combustion chamber sink341(as shown inFIG. 7), and to spill down along the inner wall of the reaction chamber20of the exhaust gas processing tank2. As a result, the water will form an inner water screen82on the inner side of the outer water screen81.

The present invention further provides a method that can be used with the whirlwind-type oxidation combustion apparatus discussed above. The method includes the following steps:

(1) The wash water supply terminal13supplies wash water to the first and second water inlets362and22at the same time, so that the outer water screen81and the inner water screen82are formed on the inner wall of the reaction chamber20and on the inner wall of the combustion chamber sink341, respectively.

(2) The combustion gas supply terminal12keeps supplying the combustion gas, which contains oxygen, into the combustion gas chamber31through the combustion gas inlet311(as shown inFIG. 7). This will force the combustion gas to be guided by the upper inclined holes51, swirl down into the ignition chamber32(seeFIG. 8), and keeps swirling down within the ignition chamber32. In the meantime, a part of the combustion gas will enter the container pipe33through the air vents331, and permeates around the igniter7.

(3) The igniter7generates electric arc sparkle (seeFIG. 7) to ignite the combustion gas inside the container pipe33to produce the pilot light flame91. The pilot light flame91will ignite the combustion gas inside the ignition chamber32to form a flame92swirling down (seeFIG. 8). This maintains the interior of ignition chamber32at a burning state. Furthermore, the flame92will be guided by the lower inclined holes61to swirl down into the combustion chamber sink341. The flame92will keep swirling down within the combustion chamber sink341and the reaction chamber20and form a concentrated vortex fire inside the combustion chamber sink341.

Through controlling the amount of the oxygen-containing combustion gas supplied to the inlet head3, the combustion gas supply terminal12can control the swirling speed of the flame92. The more combustion gas is supplied, the faster the flame92will swirl. The lesser combustion gas is supplied, the slower the flame92will swirl.

(4) Open the exhaust gas supply terminal11to supply the semiconductor fabrication exhaust gas into the exhaust gas passage4through the exhaust gas inlet41(seeFIG. 7), so that the exhaust gas will pass through the exhaust gas inlet41, the exhaust gas passage4, the exhaust gas outlet42, the combustion chamber sink341, and the reaction chamber20in turn.

In the mean time, the flame92will pre-heat the exhaust gas inside the exhaust gas passage4through the outer wall of the duct40. This can reduce the time required by the harmful objects in the exhaust gas to be catalyzed by high temperature to become harmless objects. The flame92, which is swirling down, will burn the exhaust gas, which comes from the exhaust gas outlet42of the exhaust gas passage4and enters the combustion chamber sink341and the reaction chamber20of the exhaust gas processing tank2(seeFIG. 8). The high temperature of the flame92will catalyze the harmful objects in the exhaust gas to decompose into harmless objects. The concentrated swirling fire formed by the flame92will swirl the exhaust gas and fling the exhaust gas onto the inner and outer water screens82and81, causing the dust and the fluorine ions and other objects (that can be washed away) in the exhaust gas to collide with, dissolve in, and then be discharged with the water screens82and81. This will convert the exhaust gas into a harmless one. Furthermore, the water screens82and81will also cool down the exhaust gas.

Based upon above, because the upper and lower inclined holes51and61have the same swirling direction, after the combustion gas, which swirls into the ignition chamber32through the upper inclined holes51, is ignited and becomes the flame92, the combustion gas will swirl into the exhaust gas processing tank2through the lower inclined holes61and forms the flame92that swirls down. This will cause the exhaust gas in the combustion chamber sink341of the exhaust gas processing tank2to swirl downwards.

Accordingly, the vortex flame92will cause the semiconductor fabrication exhaust gas to swirl down and pass through the high temperature flame, which is also swirling, and the wash water. This gives the exhaust gas more time to interact with the swirling flame and the wash water so that the exhaust gas will receive more uniform heating. As a result, this prevents the exhaust gas from leaving the swirling fire of the flame92without receiving enough heat. In the mean time, the upper and lower inclined holes51,61will increase the pressure of the combustion gas, causing the vortex flame92to form a concentrated swirling fire and increasing the efficiency of the flame in eliminating the harmful objects in the exhaust gas. Furthermore, the water screens81and82dissolve the harmful objects of the exhaust gas and prevent the harmful objects from adhering to the inner wall of the exhaust gas processing tank2. This further prevents the inner wall of the exhaust gas processing tank2from dirt accumulation or erosion.