TWI844078B - A semiconductor waste gas treatment system - Google Patents

Abstract

A semiconductor waste gas treatment system is composed of a vacuum pumping device, a plasma processing device and a wet scrubbing device. A two stages vacuum pumping is employed, such as a booster pump along with a dry pump. A low pressure plasma process is adopted and installed between the two pumps, leading to efficient gas reactions with a low energy consumption. Meanwhile, the back stream issues possibly caused by the plasma process is eliminated in this invention. Above all, a large flow of purge gas such as nitrogen usually used in a dry pump is not necessary, resulting in the reduction of the cost of pumping system and the amount of emission of NO _xthat is harmful to environment. In the last stage, a jet flow micro-bubble wet scrubber is used for the efficient absorption of gases and particles absorption; Moreover, it can generate a rough vacuum at the output port of the pump, which significantly increases the pumping efficiency and eliminates the particle blockage inside the pump.

Description

A semiconductor exhaust gas treatment system

The present invention relates to an exhaust gas treatment system, and more particularly to a semiconductor exhaust gas treatment system.

The semiconductor production process uses a large amount of flammable, corrosive or highly toxic reaction gases. However, the utilization rate of reaction gases is very low in many semiconductor processes. Therefore, the residual gases and reaction products that are not completely reacted during the process must be discharged from the reaction process room. These mixed gases are generally called process waste gas or tail gas and must be converted into harmless or treatable substances before they can be discharged.

The current exhaust gas system is mainly composed of a turbo vacuum pump, a mechanical pump and a local scrubber system connected to the reaction process chamber. The process exhaust gas is sequentially drawn out of the reaction process chamber through the turbo vacuum pump, exhaust pipe and mechanical pump, and then sent to the local exhaust gas treatment system for treatment and then sent to the central scrubber system for discharge.

In order to properly handle process waste gas, many technologies have been proposed and used. For example, there is a prior art that uses an exhaust pump to discharge process waste gas to a combustion scrubber for waste gas treatment before discharging the process waste gas, such as Taiwan Invention Patent No. I487872. However, the combustion scrubber is not effective in treating fluorine-containing compounds, and it must be kept in operation at all times and provide a large amount of fuel gas, so the cost is greatly increased and energy is consumed. In addition, the fuel gas is flammable and explosive, which will increase public safety hazards. In addition, although there is another prior art that uses catalyst thermal cracking, the catalyst will have aging and poisoning problems, and the cost of catalyst replacement and recycling is quite high. In addition, catalytic pyrolysis also needs to be kept running at all times and consumes a lot of energy.

In addition, although there is technology that uses plasma torch scrubbers for waste gas treatment, such as Taiwan Patent No. I285066, plasma has been proven to be effective in decomposing process waste gas, especially for perfluorinated compounds (PFCs) that require high temperature treatment. However, it operates under atmospheric pressure and consumes a lot of energy. At the same time, because the plasma temperature exceeds thousands of degrees, the system components are not only expensive but also have a short service life. In particular, atmospheric plasma has poor stability and is prone to plasma extinction due to changes in operating conditions.

On the other hand, there are theoretical technologies that propose to install a plasma treatment device before the mechanical pump to treat the exhaust gas under low pressure. The results show that because the electron energy is higher under low pressure, the exhaust gas can be effectively decomposed. Although the treatment effect is good, because the plasma treatment device is directly connected to the rear end of the turbo vacuum pump, there is a concern that the gas reactants will reflux and contaminate the process. Therefore, it cannot be accepted by the semiconductor process and is not currently used.

Most current mechanical pumps are two-stage combinations, with the first stage being a booster pump and the second stage being a dry pump. The booster pump can accelerate the system to reach a lower pressure due to its high pumping rate, which helps the second stage dry pump reach the set operating pressure. Current mechanical pump operations require the introduction of a large amount of purge gas, such as nitrogen, into the second (latter) dry pump to dilute flammable, corrosive or highly toxic process exhaust gases, and at the same time to alleviate pipeline blockage problems caused by solid particles generated during the process. Due to the large gas flow rate, a high-power exhaust pump must be used, which invisibly increases operating costs and consumes energy. Moreover, a large amount of nitrogen subsequently enters the existing local exhaust gas treatment system such as the combustion or thermal reaction scrubber, which will produce a large amount of greenhouse gases such as nitrogen oxides (NOx), causing secondary pollution to the environment.

Furthermore, even if a large amount of purge gas is introduced, solid particles will still block the second (latter) dry pump, especially at its outlet, in some processes. This will seriously reduce the exhaust efficiency and increase the operating current of the dry pump, which will not only increase energy consumption and operating costs, but may even cause damage to the dry pump and cause process shutdown.

In order to solve the above problems of the prior art, the purpose of the present invention is to provide a system that can effectively treat exhaust gas, reduce the energy consumption of mechanical pumps and significantly reduce the production of greenhouse gases such as nitrogen oxides (NOx), and effectively solve the problem of solid particle blockage to increase the service life of dry pumps. On the other hand, the present invention adopts low-pressure plasma exhaust gas treatment. Compared with the atmospheric pressure plasma torch, low-pressure plasma is easy to excite, has stable operation, low energy consumption, low component damage rate, and long maintenance cycle. More importantly, there is no problem of generating gas and particle reflux to pollute the semiconductor process chamber, so it can be accepted by the current semiconductor process system.

Different from the previous technology, the semiconductor waste gas treatment system of the present invention includes a two-stage vacuum device, a plasma treatment chamber, a reactive gas supply chamber and a jet micro-bubble wet scrubbing device. It also includes an integrated control signal to ensure that the plasma is excited and the mixed reactive gas is input only when there is process waste gas to be treated, so as to save energy and increase the service life of the plasma system.

To achieve the above-mentioned purpose, the present invention provides a semiconductor waste gas treatment system, which is suitable for treating at least one process waste gas generated by a process waste gas source, and is characterized in that the semiconductor waste gas treatment system is composed of a vacuum pumping device, a plasma treatment device and a waste gas scrubbing treatment device. Among them, the vacuum pumping device is a two-stage pump structure, which includes a first pump and a second pump. The first pump generates a first low-pressure environment to extract the process waste gas generated by the process waste gas source. The second pump generates a second low-pressure environment between the first pump and the second pump. The plasma treatment device is set in the second low-pressure environment to perform a low-pressure plasma treatment on the process waste gas, and at the same time, a suitable mixed reaction gas is added to convert the process waste gas into a harmless, stable or water-soluble reaction gas. For example, when treating a mixed gas of _CH4 and _CHF3 and introducing water gas, the treatment efficiency (Destruction Removal Efficiency, DRE) can exceed 90%. When treating NF ₃ with water-gas mixture, water vapor is dissociated by electrons in plasma into active particles of O, H, and OH, which can react with NF ₃ particles dissociated by plasma, NF _x . For example: OH + NF ₂ → NOF + HF, H + NF → N + HF, H + F → HF. HF can be effectively treated by wet scrubbing.

At the same time, low-pressure plasma treatment can also be used to miniaturize or remove solid particles carried by process exhaust gas. For example, when using NF ₃ to clean the process chamber, a mixed gas such as SiF ₄ , F, and NF _x will be generated. At the same time, residual SiO ₂ particles from the previous process will also be mixed into the exhaust gas. These particles tend to aggregate together and transform into large particles, which then settle in the dry pump to form a blockage. If the plasma is excited before entering the dry pump to make SiO ₂ react with the residual NF _x and F in the exhaust gas, the size of SiO ₂ can be reduced so that it is discharged with the gas and is not easy to accumulate in the pump.

Among them, the exhaust gas scrubbing device is a jet-type micro-bubble wet exhaust gas scrubbing device, which generates a third low-pressure environment at the outlet of the second pump by the principle of a venturi throat, and the third low-pressure environment improves the suction efficiency of the second pump, thereby significantly reducing the solid particles accumulated in the second pump. Finally, the mixed gas of the above-mentioned reaction-generated gas and particles is sucked into the wet scrubbing device to further form micro-bubbles in the scrubbing liquid, so that the scrubbing liquid fully dissolves the above-mentioned reaction-generated gas and captures the particles carried by the above-mentioned reaction-generated gas.

The vacuum pumping device is a two-stage vacuum device, and its first pump is arranged between the process waste gas source and the plasma treatment device, so as to utilize the first pump to isolate the reaction generated gas and particles obtained after the low-pressure plasma treatment to prevent them from flowing back and polluting the process waste gas source.

Among them, the process exhaust gas is converted into a stable and safe gas or a gas that can be effectively treated by the wet scrubber connected to the second pump before being sucked into the second pump. In this way, the second pump (dry pump) must input a large flow of purge gas (such as nitrogen) to dilute the flammable, corrosive or highly toxic process exhaust gas in the old technology, which can greatly reduce the operation.

The plasma treatment device switches between a standby state and an operating state according to a control signal. When the process waste gas source starts to discharge the process waste gas, the plasma treatment device switches from the standby state to the operating state to perform low-pressure plasma treatment on the process waste gas in a first low-pressure environment. When the process waste gas source stops discharging the process waste gas, the plasma treatment device switches from the operating state to the standby state.

When the plasma treatment device performs low-pressure plasma treatment on the process waste gas, it first mixes the process waste gas with a reaction gas according to the above control signal.

The plasma processing device is a plasma processing chamber and uses a mixer as a reaction gas supply chamber for introducing reaction gas so as to mix the reaction gas with process waste gas.

The process waste gases include perfluorocarbons (PFCs), nitrogen oxides (NO _x ), sulfur hexafluoride (SF ₆ ), nitrogen trifluoride (NF ₃ ), ammonia (NH ₃ ), ethyl borate (B ₂ H ₆ ), hydrofluorocarbons (HFCs), hydrocarbons (C _x H _y ) and/or CCl ₄ .

If the semiconductor process is an atomic layer deposition (ALD) process, the process exhaust gas is trimethylaluminum (TMA), tetrakis(ethylmethylamino)zirconium (TEMAZ) and/or tetrakis(ethylmethylamino)arsenic (TEMAH).

The reaction gas may be oxygen (O ₂ ), helium (He), argon (Ar), nitrogen (N ₂ ), hydrogen (H ₂ ) and/or water (H ₂ O).

The first pump of the vacuum pumping device is a booster pump, and the second pump of the vacuum pumping device is a dry pump.

The first low-pressure environment generated by the first pump of the vacuum pumping device has a pressure of 100 torr to 10 ^-3 torr.

The second low-pressure environment generated by the second pump of the vacuum pumping device has a pressure of 100 torr to 10 ^-3 torr.

The exhaust gas scrubbing device is a jet-type micro-bubble wet exhaust gas scrubbing device, and the pressure of the third low-pressure environment generated by it is 400 torr to 600 torr.

The exhaust gas scrubbing treatment device is a jet-type micro-bubble wet exhaust gas scrubbing device, which comprises: a treatment tank comprising an inner tank and an outer tank for containing a scrubbing liquid; and a jet pipe, wherein the scrubbing liquid is injected into the inner tank of the treatment tank through a jet pipe, so as to cut the above-mentioned reaction-generated gas into micro-bubbles to be dissolved in the scrubbing liquid, and then the water vapor of the scrubbing liquid lifted by the micro-bubbles overflows into the outer tank.

The plasma processing device is a radio frequency plasma generating source, a microwave plasma generating source or a high voltage discharge power source.

The plasma processing device is a microwave plasma generating source having a coaxial microwave resonant cavity.

The microwave plasma generating source includes a microwave source and a coaxially arranged metal-coupled antenna, a ceramic tube and a hollow cylinder, wherein the ceramic tube is located at the center of the cylinder and the metal-coupled antenna is located at the center of the ceramic tube, and the microwave source is arranged on the ceramic tube and at one side of the metal-coupled antenna.

Among them, the power of microwave plasma generation source ranges from 1,000W to 5,000W.

The process waste gas source is a semiconductor process chamber or a turbo vacuum pump connected to the semiconductor process chamber to discharge the process waste gas.

As mentioned above, the semiconductor waste gas treatment system of the present invention adopts a low pressure plasma treatment device and has the following advantages:

(1) The vacuum pumping device can generate a first low-pressure environment to extract the process exhaust gas generated by the process exhaust gas source. The vacuum pumping device can form a second low-pressure environment between the first pump and the second pump, and the plasma treatment device can simultaneously use the second low-pressure environment to perform low-pressure plasma treatment on the process exhaust gas. In addition, the plasma treatment device can switch from the standby state to the operating state only when the process exhaust gas begins to be discharged, so as to save energy.

(2) The exhaust gas scrubbing device is a jet-type micro-bubble wet exhaust gas scrubbing device. When the scrubbing liquid is ejected at a high speed, the reaction-generated gas obtained after low-pressure plasma treatment can be converted into micro-bubbles, which greatly increases the contact area and contact time, and helps to dissolve the above-mentioned reaction-generated gas and capture particles. At the same time, a rough vacuum state of about 400 torr to 600 torr can be generated at the air inlet, so as to effectively inhale the above-mentioned reaction-generated gas and particles from the connected vacuum pumping device for scrubbing. It can also avoid clogging of the vacuum pumping device, improve the operating efficiency of the vacuum pumping device and reduce the required power.

(3) By installing a plasma treatment device to treat the harmful process exhaust gas before it enters the second pump (dry pump), the need to dilute the toxic gas with nitrogen can be greatly reduced or even eliminated. This can reduce the generation of nitrogen oxides and carbon monoxide to avoid secondary pollution and reduce the required operating specifications, such as exhaust power and exhaust flow rate.

(4) By introducing corresponding reaction gases, such as oxygen and water vapor, stable precursors, such as oxides, can be formed, which can effectively transform difficult-to-treat process waste gases into more easily-treated reaction-generated gases, and can also miniaturize or even eliminate particles, thereby reducing toxic gases and greenhouse gases.

(5) The plasma treatment device is installed after the first pump of the vacuum exhaust device, which can effectively prevent the reaction-generated gases and particles obtained after the low-pressure plasma treatment from flowing back into the process exhaust gas source. In addition, the second pump and the exhaust gas scrubbing treatment device can also provide negative pressure suction, which is more conducive to the above-mentioned reaction-generated gases and particles flowing back into the process exhaust gas source and preventing blockage.

(6) The plasma treatment device can effectively decompose the chemical bonds of the drive before the atomic layer deposition (ALD) process, and can make the gas generated by the above reaction become a gas phase to reduce the possibility of generating particles, thereby effectively extending the maintenance cycle.

(7) The plasma treatment device may use a coaxial microwave resonant cavity structure, which has the advantage of lengthening the reaction length of microwaves and plasma to achieve the goal of uniform plasma distribution. The power used is, for example, between 1,000W and 5,000W, depending on the type and flow rate of the waste gas to be treated.

In order to enable Junshen to have a deeper understanding and recognition of the technical features and technical effects of the present invention, a preferred embodiment and a detailed description are provided as follows.

In order to facilitate understanding of the technical features, content and advantages of this invention and the effects it can achieve, this invention is described in detail as follows with the help of diagrams and in the form of embodiments. The diagrams used are only for illustration and auxiliary instructions, and may not be the true proportions and precise configurations of this invention after implementation. Therefore, the proportions and configurations of the attached diagrams should not be interpreted to limit the scope of rights of this invention in actual implementation. In addition, for ease of understanding, the same elements in the following embodiments are indicated by the same symbols.

In addition, the terms used throughout the specification and the patent application generally have the ordinary meaning of each term used in this field, in the content disclosed herein, and in the specific content, unless otherwise specified. Certain terms used to describe the present invention will be discussed below or elsewhere in this specification to provide additional guidance to those skilled in the art in describing the present invention.

The use of "first", "second", "third", etc. in this article does not specifically refer to the order or sequence, nor is it used to limit the present creation. It is only used to distinguish components or operations described with the same technical terms.

Secondly, the terms "include", "including", "have", "contain", etc. used in this article are all open terms, which mean including but not limited to.

Please refer to Figures 1 to 5. Figure 1 is a schematic diagram of the semiconductor exhaust gas treatment system of the present invention, Figure 2 is a schematic diagram of the semiconductor exhaust gas treatment system of the present invention being applied to process exhaust gas, Figure 3 is a schematic diagram of the exhaust gas scrubbing treatment device of the present invention using a jet-type micro-air bubble wet exhaust gas scrubbing device, Figure 4 is a schematic diagram of the microwave plasma generation source of the present invention, and Figure 5 is a schematic diagram of the semiconductor exhaust gas treatment concept of the present invention being applied to modifying the existing exhaust gas treatment system.

As shown in FIG. 1 to FIG. 3 , the semiconductor waste gas treatment system 10 of the present invention is composed of a vacuum pumping device 30, a plasma treatment device 40 and a waste gas scrubbing treatment device 50. When applied to process waste gas, the present invention connects the vacuum pumping device 30 to the exhaust end of the process waste gas source 20, and the vacuum pumping device 30 can generate a first low-pressure environment between the process waste gas source 20 and the vacuum pumping device 30 during operation, and the process waste gas 12 generated by the process waste gas source 20 can be sucked in by generating a negative pressure. The plasma treatment device 40 is disposed on the vacuum exhaust device 30 (between the first pump 32 and the second pump 34), and performs low-pressure plasma treatment on the process exhaust gas through the second low-pressure environment between the first pump 32 and the second pump 34, so as to make the process exhaust gas 12, which is originally difficult to treat, become the reaction-generated gas 16 that is easier to treat, so that it is easier to dissolve in the cleaning liquid, and the particles carried by the process exhaust gas 12 are miniaturized, or even eliminated, to prevent blockage and be easier to be captured. Therefore, the present invention can greatly reduce or eliminate the need to dilute the process exhaust gas. Since the gas flow rate becomes lower, the operating specifications of the vacuum exhaust device 30, such as the exhaust power and/or the exhaust rate, can naturally be greatly reduced. At the same time, the first pump 32 of the vacuum pumping device establishes isolation between the plasma treatment device 40 and the process waste gas source 20, so that the reaction generated gas 16 or particles obtained after the low-pressure plasma treatment cannot flow back to the process waste gas source 20 to cause pollution. The exhaust gas scrubbing treatment device 50 can generate a third low-pressure environment (between the second pump 34 and the exhaust gas scrubbing treatment device 50) when in operation. By generating a negative pressure, the reaction-generated gas 16 obtained after the low-pressure plasma treatment can be effectively sucked in to prevent blockage and backflow. In addition, the reaction-generated gas 16 can be converted into microbubbles by the scrubbing liquid. By greatly increasing the contact area and contact time, the scrubbing liquid can fully dissolve the reaction-generated gas 16 and the particles it carries.

In detail, the process waste gas source 20 is, for example, a semiconductor process chamber for performing semiconductor processes, and the process waste gas 12 is, for example, waste gas discharged by the semiconductor process, such as toxic waste gas or greenhouse gas carrying particulates. The present invention is not limited to a specific semiconductor process chamber and the type of semiconductor process implemented therein. As long as the process waste gas 12 is generated, it is suitable for waste gas treatment by the semiconductor waste gas treatment system 10 of the present invention. For example, depending on the actual semiconductor process being performed, the process waste gas source 20 of the present invention may be, for example, a semiconductor process chamber or a semiconductor process system in which the semiconductor process chamber is equipped with a turbo pump to discharge process waste gas. In other words, the process waste gas source 20 applicable to the semiconductor waste gas treatment system 10 of the present invention is not limited to the above examples, and any waste gas source that discharges semiconductor process waste gas may be applicable to the present invention. The process waste gas 12 is a process waste gas generated in a semiconductor process, such as, but not limited to, toxic gases or greenhouse gases such as perfluorocarbons (PFCs), nitrogen oxides (NOx), sulfur hexafluoride (SF ₆ ), nitrogen trifluoride (NF ₃ ), ammonia (NH ₃ ), ethyl borate (B ₂ H ₆ ), hydrofluorocarbons (HFCs) and/or hydrocarbons (C _x H _y ). If the semiconductor process is an atomic layer deposition (ALD) process, the process waste gas is, for example, but not limited to, trimethylaluminum (TMA), tetrakis(ethylmethylamino)zirconium (TEMAZ) and/or tetrakis(ethylmethylamino)arsenic (TEMAH).

In detail, the vacuum exhaust device 30 of the semiconductor waste gas treatment system 10 of the present invention includes, for example, a two-stage combination of a first pump 32 and a second pump 34. The inlet end 32a of the first pump 32 is connected to the exhaust end of the process waste gas source 20 through the first pipe a1, and a first low-pressure environment is generated in the first pipe a1 (i.e., between the first pump 32 and the process waste gas source 20) to extract the process waste gas 12 generated by the process waste gas source 20. The exhaust end 32b of the first pump 32 is connected to the mixer 60, the plasma processing device 40 and the inlet end 34a of the second pump 34 through the second pipe a2. The second pump 34 of the vacuum pumping device 30 establishes a second low-pressure environment between the first pump 32 and the second pump 34. The air pressure of the first low-pressure environment generated by the first pump 32 is, for example, about 100 torr to 10 ^-3 torr, and the air pressure of the second low-pressure environment generated by the second pump 34 is, for example, about 100 torr to 10 ^-3 torr. For example, the working pressure range of the first pump 32 is, for example, about 100 torr to 10 ^-3 torr, and the working pressure range of the second pump 34 is, for example, about 100 torr to 10 ^-3 torr. The first pump 32 is, for example, a booster pump, and the second pump 34 is, for example, a dry pump. The vacuum pumping device 30 of the present invention uses not only the first pump 32 but also the second pump 34, thereby providing auxiliary suction to help accelerate the achievement of the required vacuum level. The first pump 32 also isolates the gas and particles in the second pipe a2 from flowing back to the process waste gas source 20. Although the pressure ranges of the first low-pressure environment and the second low-pressure environment of the vacuum pumping device 30 and the working pressure ranges of the first pump 32 and the second pump 34 are listed above, the scope of the present invention is not limited thereto. As long as the pump can provide a low-pressure environment, it falls within the scope of protection claimed by the present invention.

In other words, the plasma treatment device 40 of the semiconductor waste gas treatment system 10 of the present invention is disposed between the first pump 32 and the second pump 34 of the vacuum exhaust device 30, so that before the process waste gas enters the second pump 34, the plasma treatment device 40 first uses the second low-pressure environment generated by the second pump 34 to perform low-pressure plasma treatment on the process waste gas that is more difficult to treat, so as to convert the process waste gas into a more easily treated reaction product gas 16 and to miniaturize the particles carried by the process waste gas. Therefore, the present invention can greatly reduce the purge gas (such as nitrogen) required by the second pump 34 to dilute the process waste gas, and greatly reduce the power required for exhaust. At the same time, it can also prevent the vacuum pumping device from being slightly blocked. Moreover, the vacuum pumping device 30 isolates the plasma processing device 40 from the process waste gas source 20, so that the reaction-generated gas 16 or particles cannot flow back to the process waste gas source 20 to cause pollution.

In addition, the plasma treatment device 40 of the present invention can selectively switch between a standby state and an operating state according to the control signal 80. For example, when the process waste gas source 20 starts to discharge the process waste gas 12, the plasma treatment device 40 switches from the standby state to the operating state to perform low-pressure plasma treatment on the process waste gas 12 in the second low-pressure environment; when the process waste gas source 20 stops discharging the process waste gas 12, the plasma treatment device 40 switches from the operating state to the standby state, and does not need to be kept running all the time, so the required energy can be saved.

In detail, the plasma treatment device 40 of the present invention provides a plasma channel 42 having plasma connected between the exhaust end 32b of the first pump 32 and the intake end 34a of the second pump 34 of the vacuum pumping device 30, for example, detachably or fixedly arranged on the second pipe a2. The process waste gas 12 is, for example, first mixed with at least one reaction gas 14 corresponding to the process waste gas 12, and then passes through the plasma channel 42, so that the process waste gas 12 and the reaction gas 14 react with the plasma in the plasma channel 42, so as to convert the process waste gas 12 into at least one reaction product gas 16, and to micronize the particles carried by the process waste gas 12, or even completely remove the particles. The type of the reaction gas 14 corresponds to the process waste gas 12 mentioned above, that is, the type of the reaction gas 14 is determined by the process waste gas 12, so that the process waste gas 12 and the reaction gas 14 react with plasma to form a predetermined reaction product gas 16. The reaction gas 14 mentioned above is, for example, oxygen (O ₂ ), helium (He), argon (Ar), nitrogen (N ₂ ), hydrogen (H ₂ ) and/or water vapor (H ₂ O). The reaction product gas 16 obtained after low-pressure plasma treatment is harmless, stable or soluble in water, which is easier to handle. For example, when water vapor is introduced into the mixed gas of CH ₄ and CHF ₃ , the treatment efficiency (Destruction Removal Efficiency, DRE) can exceed 90%. For example, when NF ₃ is treated by mixing water and gas, water gas is dissociated by electrons in plasma into active particles of O, H, and OH, which can react with particles NF _x dissociated by NF _3. For example: OH + NF ₂ → NOF + HF, H + NF → N + HF, H + F → HF. HF can be effectively treated by wet washing. Taking the RF plasma generation source as an example, the electrode structure of the plasma treatment device 40 can be, for example, a columnar, plate-shaped, or mesh-shaped structure, as long as a plasma channel 42 with plasma can be formed, it can be applied to the present invention.

In addition, the present invention can selectively introduce the above-mentioned reaction gas 14 through the mixer 60 according to the control signal 80, that is, when the process waste gas source 20 starts to discharge the process waste gas 12, the reaction gas 14 is introduced, wherein the plasma channel 42 of the plasma processing device 40 is connected to the mixer 60, and the process waste gas 12 is, for example, first mixed with the reaction gas 14 by the mixer 60 and then enters the plasma channel 42 for reaction. The mixer 60 is, for example, disposed on the second pipe a2 and disposed in front of the gas inlet end 42a of the plasma channel 42 of the plasma processing device 40. That is, the mixer 60, for example, has a first gas inlet end 60a, a second gas inlet end 60c and a gas exhaust end 60b connected to the mixing chamber 61, wherein the first gas inlet end 60a of the mixer 60 is connected to the gas exhaust end 32b of the first pump 32 for introducing the process waste gas 12, and the gas exhaust end 60b of the mixer 60 is connected to the gas inlet end 42a of the plasma channel 42 of the plasma treatment device 40 for guiding out the mixed process waste gas 12 and the reaction gas 14. The mixer 60, for example, has a fourth pipe a4, and one end of the fourth pipe a4 is connected to the mixing chamber 61 of the mixer 60, and the other end of the fourth pipe a4 has a second gas inlet end 60c for introducing the reaction gas 14, so that the process waste gas 12 can be uniformly mixed with the reaction gas 14 in the mixing chamber 61. The form and size of the mixer 60 and its mixing chamber 61 are not particularly limited, as long as the process waste gas 12 can be mixed with the reaction gas 14, it can be applied to the present invention. In addition, the mixer 60 used in the present invention can also have a regulating valve (not shown) disposed at the first gas inlet end 60a and the second gas inlet end 60c, for example, to adjust the corresponding supply amount of the process waste gas 12 and the reaction gas 14, so as to obtain a better reaction effect. In other words, the present invention can integrate the control signal 80 to ensure that the operation mode of igniting plasma and inputting mixed reaction gas is used to save energy and increase the service life of the plasma system.

Taking the plasma treatment device 40 as the microwave plasma generation source, as shown in FIG. 4 , as an example, the mixed gas of the process waste gas 12 and the reaction gas 14 is discharged from the exhaust port 60b of the mixer 60 and enters the cylindrical microwave resonant cavity through the pipe 1 and the pipe 2. The high-power microwave (about 1,000 W to about 5,000 W) decomposes the mixed gas into a plasma state in the plasma channel 42. Under low pressure, the electrons can obtain sufficient energy to collide with the gas molecules to cause a decomposition reaction. At the same time, the molecules, atoms and activated particles generated also produce various chemical and physical reactions, thereby achieving the goal of waste gas treatment. The reaction generated gas 16 obtained after the low-pressure plasma treatment then enters the second pump 34 through the pipe 3 and the pipe 4. In detail, the cylindrical microwave resonance cavity of the microwave plasma generating source includes a coaxially arranged metal-coupled antenna 6, a ceramic tube 7 and a cylinder 8, wherein the ceramic tube 7 is located at the center of the hollow cylinder 8 and the antenna 6 is located at the center of the ceramic tube 7, and the microwave source 5 is arranged on the ceramic tube 7 and at one side of the antenna 6.

The above-mentioned microwave plasma treatment device uses a coaxial microwave resonant cavity structure, which has the advantage of being able to lengthen the reaction length of microwaves and plasma to achieve the goal of uniform plasma distribution. The plasma of a general cylindrical or rectangular microwave resonant cavity tends to be easily concentrated near the entrance, and it is not possible to effectively form a uniform plasma. The coaxial microwave distribution is achieved by the microwave source 5 through the metal coupling antenna 6 and the ceramic tube 7 and the external cylinder 8. The ceramic tube 7 can effectively transmit the microwave on the antenna 6 without causing the microwave source coupling plasma reaction to be concentrated near the entrance, and at the same time, it also achieves the function of isolating the vacuum and protecting the antenna 6 from being destroyed by the plasma. However, the type of plasma processing device 40 of the present invention is not limited to the above-mentioned microwave plasma generating source, and any existing technology such as radio frequency plasma generating source or high-pressure discharge power source can be adopted. As long as the plasma channel 42 can be formed in a low-pressure environment and the process exhaust gas 12 and the reaction gas 14 can react, they can be applicable to the present invention.

The exhaust gas cleaning treatment device 50 of the semiconductor exhaust gas treatment system 10 of the present invention uses the Venturi throat principle to make the jet structure spray out the cleaning liquid 59, and generate the above-mentioned third low-pressure environment between the second pump 34 and the exhaust gas cleaning treatment device 50 to absorb the reaction generated gas 16 obtained after the low-pressure plasma treatment, and convert the reaction generated gas 16 into micro bubbles. By greatly increasing the contact area and contact time, the cleaning liquid can fully dissolve the reaction generated gas 16 and capture particles. Therefore, the present invention can prevent the vacuum exhaust device from being blocked, effectively extend the maintenance cycle, and prevent backflow pollution, so that the process exhaust gas can be treated in an energy-saving, environmentally friendly and stable manner. In detail, as shown in FIG3 , the waste gas scrubbing treatment device 50 used in the present invention is a jet-type micro-bubble wet waste gas scrubber using the Venturi tube principle. The waste gas scrubbing treatment device 50 uses a negative pressure jet pipe 51 to vertically eject a scrubbing liquid 59 at high speed and generate a third low-pressure environment (negative pressure of about 400 torr to 600 torr), so as to utilize a third pipe a3 to suck the reaction-generated gas 16 converted from the process waste gas 12 through the second pump 34. The volume of the scrubbing liquid 59, for example, accounts for about 50% to 90% of the volume of the inner tank 53 of the treatment tank, preferably about 60% to 80%, and more preferably about 70%. Moreover, when the washing liquid 59 is impacted downwardly by the negative pressure jet tube 51 at a high speed into the washing liquid 59 in the inner tank 53 of the treatment tank, the reaction generated gas 16 will be cut to form a plurality of micro bubbles (average diameter less than about 1.0 mm) in the washing liquid 59, which are much smaller than conventional bubbles, and thus have a much larger surface area than conventional bubbles. In addition, in the process of the micro bubbles moving upward from the depth of the washing liquid 59 in the inner tank 53 of the treatment tank, the contact area and contact time are greatly increased, so that the micro bubbles can fully contact the washing liquid 59. Because the reaction generated gas 16 will dissolve in the washing liquid 59, the micro bubbles will gradually shrink in volume during the rising process and then disappear in the washing liquid 59. The water vapor of the washing liquid 59 raised by the microbubbles will overflow into the outer tank 54. The washing liquid 59 contains chemicals for treating the corresponding reaction-generated gas 16. The chemicals are selected from the group consisting of, for example but not limited to, saline solution, sodium hydroxide, calcium hydroxide, calcium carbonate and sodium bicarbonate. That is, the composition of the washing liquid 59 can be determined by the reaction-generated gas 16 to be treated, and a suitable alkali can be used for neutralization to reduce the formation of an acidic solution. For example, a solution composed of fresh water and sodium hydroxide or other neutralizers (such as lime) can effectively extract and neutralize a large amount of HCl, _SO2 or other acid-containing components in the reaction-generated gas 16. For example, calcium hydroxide (Ca(OH) ₂ ), calcium carbonate (CaCO ₃ ) and/or sodium bicarbonate (NaHCO ₃ ) may also be mixed with the cleaning solution 59 to help absorb other acidic process exhaust gases from various production sources. Therefore, when the microbubbles contact the cleaning solution 59, the reaction-generated gas 16 will be fully dissolved in the cleaning solution 59, and the cleaning solution 59 can fully capture the particles.

Subsequently, the washed gas that is not dissolved by the washing liquid 59 diffuses to the liquid surface of the inner tank 53 along with the washing liquid 59 to form water vapor. Therefore, the gas-liquid separation component 56 above the inner tank 53 can play the role of filtering and capturing water vapor and only allow the above-mentioned washed gas to pass through the gas-liquid separation component 56. Therefore, the processed dry washed gas can be discharged from the discharge channel 57, for example, to a central exhaust gas treatment system. In addition, the above-mentioned gas-liquid separation component can also be added to the discharge channel 57 to discharge drier washed gas by capturing water vapor. The gas-liquid separation assembly 56 can be any structure capable of separating liquid and gas, such as a fiber bed demister composed of glass fibers with a diameter of about 100 microns to 1 micron, so as to filter water vapor and only allow gas to pass through it. As for the washing liquid 59 blocked by the gas-liquid separation assembly 56, it will fall into the outer tank 54. Subsequently, for example, the filter assembly 55 can be used to filter the washing liquid 59 in the outer tank 54 of the treatment tank, and then the water pump 58 can be used to inject the filtered washing liquid 59 in the outer tank 54 back into the inner tank 53 of the treatment tank through the negative pressure jet tube 51, so as to cyclically generate negative pressure and cut the reaction generated gas 16 to form a plurality of micro bubbles in the washing liquid 59.

The negative pressure jet pipe 51 described above, for example, has a suction chamber 72 and a jet pipe 74. The side wall of the suction chamber 72 has at least one suction port for connecting to the third pipe a3 through the gas pipeline 52. The top of the jet pipe 74 is an injection port for injecting washing liquid 59. The bottom of the jet pipe 74 is an injection port extending to the inside of the suction chamber 72. By spraying the washing liquid 59 into the suction chamber 72, negative pressure suction is generated. The gas pipeline 52 can be, for example, vertically or obliquely arranged on the side wall of the suction chamber 72. The gas pipeline 52 is preferably obliquely arranged on the side wall of the suction chamber 72. The bottom of the suction chamber 72 is connected to a mixing tube 76 and a diffusion tube 78 in sequence, and the mixing tube 76 and/or the diffusion tube 78 are immersed in the washing liquid 59 of the inner tank 53. It is preferred that the microbubbles reach the bottom of the inner tank 53 by the momentum of the downward jet impact, and then move upward from the bottom, thereby increasing the time that the microbubbles contact the washing liquid 59. The time that the microbubbles pass through the washing liquid 59 is, for example, about 1 to 20 seconds, preferably about 1 to 10 seconds. In addition, the cavity wall of the suction cavity 72 and/or the gas pipeline 52 may optionally have a cleaning member, such as a nozzle, for example, to first spray the cleaning liquid 59 and then spray the air, so as to achieve the effect of cleaning the interior of the cavity wall and keep the cavity wall of the suction cavity 72 and/or the gas pipeline 52 dry. In addition, the cleaning member is preferably to spray the cleaning liquid 59 and the air into the suction cavity 72 and/or the gas pipeline 52 at a high speed in sequence along the tangent direction of the cavity wall of the suction cavity 72 and/or the gas pipeline 52 and slightly inclined, so as to generate a spiral airflow flowing from top to bottom along the suction cavity 72 and/or the gas pipeline 52, which can effectively prevent the generation of deposits.

Since the process waste gas generated by the semiconductor process carries a large amount of particles, the traditional technology must use a large amount of purge gas (such as nitrogen) to dilute the pumping gas (i.e., process waste gas) to avoid blockage, such as blockage of the vacuum pumping device, so as to prevent blockage problems. Therefore, a high-performance pump must be used for pumping, which invisibly increases operating costs and consumes energy. Compared with traditional technology, the present invention can significantly reduce the dilution of process waste gas or eliminate the need to dilute process waste gas, and can also significantly reduce the required operating specifications, such as pumping power or pumping rate. The present invention pre-treats the process waste gas 12 by the plasma treatment device 40 before the process waste gas enters the second pump 34, which can effectively decompose the chemical bonding of the precursor to reduce the possibility of generating particles, and make the reaction product gas 16 become a gas phase. In other words, the present invention can not only transform the process waste gas 12 into a harmless, stable or reaction product gas 16 that is more easily soluble in the cleaning liquid, but also reduce the size of solid particles so that they can be easily captured by the cleaning liquid, or even completely remove the particles, so the present invention is not prone to clogging. It can be seen that the present invention can use lower exhaust power, extend the maintenance cycle, and prevent secondary pollution of the environment. In addition, the semiconductor waste gas treatment system of the present invention performs plasma treatment under low pressure, and the component damage rate is lower and more stable. Therefore, the present invention can achieve the effects of energy saving, environmental protection and stable treatment of process waste gas.

In addition, the waste gas scrubbing treatment device 50 of the present invention can not only treat the reaction generated gas 16, but also generate a third low-pressure environment, which can provide negative pressure suction, reduce the power required for the operation of the vacuum pumping device 30, and avoid the blockage of the vacuum pumping device 30. In detail, the air inlet 50a of the waste gas scrubbing treatment device 50 is connected to the exhaust end 34b of the second pump 34 of the vacuum pumping device 30 through the third pipe a3 to suck the reaction generated gas 16. The waste gas scrubbing treatment device 50 is, for example, a wet waste gas scrubber and/or a dry waste gas scrubber. The exhaust gas scrubber 50 of the present invention is preferably a wet exhaust gas scrubber that can provide negative pressure suction, and more preferably a jet-type micro-bubble wet exhaust gas scrubber that can generate a third low-pressure environment of a rough vacuum state (about 400 torr-600 torr). Since the exhaust gas scrubber 50 is connected to the second pump 34, the negative pressure suction generated by the exhaust gas scrubber 50 between the second pump 34 and the exhaust gas scrubber 50 can provide auxiliary suction, which helps the reaction product gas 16 to be discharged into the exhaust gas scrubber 50 through the second pump 34. In other words, by using the negative pressure suction force generated by the exhaust gas scrubbing treatment device 50, the present invention can prevent the reaction gas 16 and particles obtained after the low-pressure plasma treatment from flowing back, prevent the second pump 34 from being blocked, and reduce the power required for the operation of the vacuum pumping device 30.

In addition, according to the semiconductor exhaust gas treatment concept of the present invention, as shown in FIG. 5 , the present invention can be applied to modify the existing exhaust gas treatment system. For example, the vacuum pump installed in the existing semiconductor can be modified to separate the booster pump (i.e., the first pump 32) and the dry pump (i.e., the second pump 34), add a gas mixer (i.e., the mixer 60) and a plasma treatment device 40, and add a jet-type micro-bubble wet exhaust gas scrubber to form a local exhaust gas treatment system to replace the existing electric heating or combustion local exhaust gas treatment system.

In summary, the semiconductor waste gas treatment system of the present invention adopts a low pressure plasma treatment device and has the following advantages:

(1) The vacuum pumping device can generate a first low-pressure environment to extract the process waste gas generated by the process waste gas source. The vacuum pumping device can form a second low-pressure environment between the first pump and the second pump, and the plasma treatment device can simultaneously use the second low-pressure environment to perform low-pressure plasma treatment on the process waste gas. In addition, the plasma treatment device can switch from a standby state to an operating state only when the process waste gas begins to be discharged, so as to save energy.

(2) The exhaust gas scrubbing device is a jet-type micro-bubble wet exhaust gas scrubbing device. When the scrubbing liquid is ejected at a high speed, the reaction-generated gas obtained after low-pressure plasma treatment can be converted into micro-bubbles, which greatly increases the contact area and contact time, and helps to dissolve the above-mentioned reaction-generated gas and capture particles. At the same time, a rough vacuum state of about 400 torr to 600 torr can be generated at the air inlet to inhale the above-mentioned reaction-generated gas and particles for scrubbing. It can also avoid clogging of the vacuum pumping device, improve the operating efficiency of the vacuum pumping device and reduce the required power.

(3) By installing a plasma treatment device to treat the harmful process exhaust gas before it enters the second pump (dry pump), the need to dilute the toxic gas with nitrogen can be greatly reduced or even eliminated. This can reduce the generation of nitrogen oxides and carbon monoxide to avoid secondary pollution and reduce the required operating specifications, such as exhaust power and exhaust flow rate.

(4) By introducing corresponding reaction gases, such as oxygen and water vapor, stable precursors, such as oxides, can be formed, which can effectively transform difficult-to-treat process waste gases into more easily treatable reaction products, and can also miniaturize or even eliminate particles, thereby reducing toxic gases and greenhouse gases.

(5) The plasma treatment device is installed after the first pump of the vacuum exhaust device, which can effectively prevent the reaction-generated gases and particles obtained after the plasma treatment from flowing back into the process exhaust gas source. In addition, the second pump and the exhaust gas scrubbing treatment device can also provide negative pressure suction, which is more helpful to prevent the reaction-generated gases and particles from flowing back into the process exhaust gas source and prevent clogging.

(6) Plasma treatment equipment can effectively decompose the chemical bonds of the drive before the atomic layer deposition (ALD) process, and can make the reaction-generated gas become a gas phase to reduce the possibility of generating particles, thus effectively extending the maintenance cycle.

(7) The plasma treatment device may use a coaxial microwave resonant cavity structure, which has the advantage of lengthening the reaction length of microwaves and plasma to achieve the goal of uniform plasma distribution. The power used is, for example, between 1,000W and 5,000W, depending on the type and flow rate of the waste gas to be treated.

The above description is for illustrative purposes only and is not intended to be limiting. Any equivalent modifications or changes made to the invention without departing from the spirit and scope of the invention shall be included in the scope of the attached patent application.

FIG1 is a schematic diagram of a semiconductor exhaust gas treatment system of the present invention.

FIG. 2 is a schematic diagram showing the semiconductor exhaust gas treatment system of the present invention being applied to treat process exhaust gas.

FIG. 3 is a schematic diagram of the exhaust gas scrubbing device of the present invention using a jet-type micro-air bubble wet exhaust gas scrubbing device.

FIG. 4 is a schematic diagram of the plasma treatment device of the present invention using a microwave plasma generating source, wherein FIG. 4(B) is a schematic diagram obtained along the I-I' section line of FIG. 4(A).

FIG. 5 is a schematic diagram showing the semiconductor exhaust gas treatment concept of the present invention being applied to modify the existing exhaust gas treatment system.

10: Semiconductor exhaust gas treatment system

12: Process exhaust gas

14: Reaction gas

16: Reaction generates gas

30: Vacuum exhaust device

32: First Pump

32a: Intake end

32b: Exhaust end

34: Second Pump

34a: Intake end

34b: Exhaust end

40: Plasma treatment device

42a: Intake end

42: Plasma channel

50: Waste gas scrubbing treatment device

50a: Intake end

60:Mixer

60a: First air intake end

60b: Exhaust end

60c: Second intake end

61: Mixing chamber

a1: The first pipe fitting

a2: Second pipe fitting

a3: The third pipe fitting

a4: The fourth pipe fitting

80: Control signal

Claims (17)

A semiconductor waste gas treatment system is suitable for treating at least one process waste gas generated by a process waste gas source, and its characteristics are: The semiconductor waste gas treatment system is composed of a vacuum pumping device, a plasma treatment device and a waste gas scrubbing treatment device; Wherein, the vacuum pumping device adopts a two-stage combination of a first pump and a second pump, the first pump generates a first low-pressure environment to extract the process waste gas generated by the process waste gas source, and the second pump generates a second low-pressure environment between the first pump and the second pump; The plasma treatment device is disposed between the first pump and the second pump, so that before the process waste gas enters the second pump, the plasma treatment device first performs a low-pressure plasma treatment on the process waste gas in the second low-pressure environment, so as to convert the process waste gas into a reaction-generated gas and miniaturize or remove a plurality of particles carried by the process waste gas; and The exhaust gas scrubbing treatment device generates a third low-pressure environment between the second pump and the exhaust gas scrubbing treatment device by spraying a scrubbing liquid through a negative pressure jet pipe. The negative pressure jet pipe absorbs the reaction-generated gas and the particles obtained after the low-pressure plasma treatment through the second pump, and the reaction-generated gas is cut into a plurality of microbubbles by the sprayed scrubbing liquid, so that the scrubbing liquid fully dissolves the reaction-generated gas and captures the particles carried by the reaction-generated gas. The air pressure of the third low-pressure environment generated by the exhaust gas scrubbing treatment device is 400 torr to 600 torr. A semiconductor waste gas treatment system as described in claim 1, wherein the first pump of the vacuum pumping device is arranged between the process waste gas source and the plasma treatment device, so as to utilize the first pump to isolate the reaction generated gas and the particles carried by it obtained after the low-pressure plasma treatment to prevent them from backflowing and contaminating the process waste gas source. A semiconductor exhaust gas treatment system as described in claim 1, wherein the plasma treatment device switches between a standby state and an operating state according to a control signal. When the process exhaust gas source starts to discharge the process exhaust gas, the plasma treatment device switches from the standby state to the operating state to perform the low-pressure plasma treatment on the process exhaust gas in the second low-pressure environment. When the process exhaust gas source stops discharging the process exhaust gas, the plasma treatment device switches from the operating state to the standby state. A semiconductor exhaust gas treatment system as described in claim 3, wherein the plasma treatment device performs the low-pressure plasma treatment on the process exhaust gas and simultaneously mixes the process exhaust gas with a reactive gas according to the control signal. A semiconductor exhaust gas treatment system as described in claim 4, wherein the plasma treatment device uses a mixer to introduce the reaction gas so that the reaction gas is mixed with the process exhaust gas. The semiconductor exhaust gas treatment system as described in claim 1, wherein the process exhaust gas is perfluorocarbons (PFCs), nitrogen oxides (NOx), sulfur hexafluoride (SF ₆ ), nitrogen trifluoride (NF ₃ ), ammonia (NH ₃ ), ethyl borate (B ₂ H ₆ ), hydrofluorocarbons (HFCs), hydrocarbons (C _x H _y ) and/or CCl ₄ . A semiconductor exhaust gas treatment system as described in claim 1, wherein if the process exhaust gas source performs an atomic layer deposition (ALD) process, the process exhaust gas is trimethylaluminum (TMA), tetrakis(ethylmethylamino)zirconium (TEMAZ) and/or tetrakis(ethylmethylamino)arsenic (TEMAH). The semiconductor exhaust gas treatment system as described in claim 6 or 7, wherein the reaction gas is oxygen ( _O2 ), helium (He), argon (Ar), nitrogen ( _N2 ), hydrogen ( _H2 ) and/or water ( _H2O ). A semiconductor exhaust gas treatment system as described in claim 1, wherein the first pump is a boost pump and the second pump is a dry pump. The semiconductor exhaust gas treatment system as described in claim 1, wherein the pressure of the first low-pressure environment generated by the first pump of the vacuum exhaust device is 100 torr to 10 ^-3 torr. The semiconductor exhaust gas treatment system as described in claim 1, wherein the pressure of the second low-pressure environment generated by the second pump of the vacuum exhaust device is 100 torr to 10 ^-3 torr. The semiconductor waste gas treatment system as described in claim 1, wherein the waste gas washing treatment device comprises: a treatment tank, comprising an inner tank and an outer tank, for containing the washing liquid; and the negative pressure jet pipe, wherein the washing liquid is injected into the inner tank of the treatment tank through the negative pressure jet pipe, so as to cut the reaction generated gas into the micro bubbles to be dissolved in the washing liquid, and then the water vapor of the washing liquid raised by the micro bubbles overflows into the outer tank. The semiconductor exhaust gas treatment system as described in claim 1, wherein the plasma treatment device is a radio frequency plasma generation source, a microwave plasma generation source or a high pressure discharge power source. A semiconductor exhaust gas treatment system as described in claim 1, wherein the plasma treatment device is a microwave plasma generation source having a coaxial microwave resonant cavity. A semiconductor exhaust gas treatment system as described in claim 14, wherein the microwave plasma generating source comprises a microwave source and a coaxially arranged metal-coupled antenna, a ceramic tube and a hollow cylinder, wherein the ceramic tube is located at the center of the cylinder and the metal-coupled antenna is located at the center of the ceramic tube, and the microwave source is arranged on the ceramic tube and at one side of the metal-coupled antenna. A semiconductor exhaust treatment system as described in claim 14, wherein the power of the microwave plasma generating source is between 1,000 W and 5,000 W. A semiconductor exhaust gas treatment system as described in claim 1, wherein the process exhaust gas source is a semiconductor process chamber or a turbine vacuum pump connected to the semiconductor process chamber to exhaust the process exhaust gas.