xhaust gas cleaning by thermal decomposition and wet scrubber
SemiAn Technology is represented in Europe by
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This type of exhaust gas cleaning system consists of several units. In a first step soluble and corrosive gases can be abated by a washer in order to protect the burner. SWB series abatement systems for waste gas treatment include this option, SBW series abatement is delivered without this option. A pre-washer is recommendable, when the exhaust gas contains hydrogen halides like HCl and HBr, which are very corrosive or when they contain metal halides like WF6. The second step is the main unit of the gas cleaner: the burn chamber, where the electrical combustion of insoluble compounds happens. Here the waste gas is heated and oxidized in order to destroy toxic compounds. Very important is the temperature distribution in this combustion unit. It has to made sure that the gas reaches a minimum temperature in order to crack the toxic components. During this decomposition quite often a lot of dust is generated and sometimes also soluble or corrosive gases. This dust has to be removed also from the exhaust gas. This can be achieved in two steps, using a swirl unit and a two step wet scrubber unit. As an option, a cooler can be installed inside the circulation tank. Remaining moisture is removed in a demister.
Several types of burn and wet abatement systems are available, listed in the following table. All main parts are made of stainless steel, the reactor is made of Inconel and the circulation pump is teflon coated. The reactor is equipped with a multi-construction heater and an auto-cleaning system. The process control is done by PLC control, heater power detection system, SRC heater power control and visualization achieved by a TFT monitor. As an option, a central, PC based monitoring system is available. Several scrubber can be connected to this system. The status of all scrubbers can be displayed there. Improved safety functions, various interlocks and water leak detection systems are installed. The footprint of the system is small and total equipment is designed in order to work at lowest cost.
SemiAn offers abatement systems consisting of an electrical combustion and a wet scrubber, which have been developed for cleaning waste gas from single process tools, as they are used in the semiconductor and LCD industry. Therefore our gas cleaner are sized for a gas flow in the range of 100 - 1.200 slm or 6 - 72 m3/h. Of course, we can also offer gas scrubber of that size for other applications also. Our equipment is reliable and cost effective.
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| SBW200 |
SWB200 |
SBW201 |
Gas treatment and abatement type scrubber for high temperature oxidative reaction and soluble gas treatment by wet scrubbing with circulation system. This system is mainly used for the cleaning of exhaust gas from ion implantors, PE-CVD, LP-CVD, and AP-CVD equipment as well as for MO-CVD (Optoelectronics).
Gas treatment and abatement type pre-wet scrubber and oxidative reactor and main wet scrubber. Exhaust gas cleaning is achieved in three steps: Abatement of soluble gases and by-products in pre-wet scrubbing section, treatment of pyrophoric, inflammable gases in high temperature oxidative reactor section, treatment of soluble gases by wet scrubbing with a circulation system. This system is used mainly in combination with PE-CVD (semiconductor and LCD manufacturing), LP-CVD, AP-CVD and MO-CVD (optoelectronics).
Large version of the burn-wet scrubber, consisting of several parallel oxidative reactors and a main wet scrubber. Exhaust gas cleaning is achieved in two steps: Treatment of pyrophoric, inflammable gases in high temperature oxidative reactor section and treatment of soluble gases by wet scrubbing with a circulation system. This system is used for LCD manufacturing in combination with PE-CVD, for MO-CVD (optoelectronics) and for epitaxy reactors.
The following chemicals can be removed from the exhaust gas. In
the table the maximum inlet concentration and the minimum outlet concentration
for several gases are given as well as the related TLV (Threshold Limit Values).
The chemical reaction describes the oxidation in the burner. In the wet scrubber,
HF and HCl are then dissolved. Chlorine reacts in the wet scrubber
with water to HCl and hypochloric acid HClO.
| Gas | Max. inlet
concentration in ppm |
Min. outlet
concentration in ppm |
TLV in ppm |
Efficiency in % |
Chemical reaction (combustion) |
| AsH3 | 5,000 | 0.01 | 0.05 | >99.99 | 2 AsH3 + 3 O2 As2O3+ 3 H2O |
| B2H6 | 2,500 | 0.01 | 0.1 | >99.99 | B2H6 + 3 O2B2O3+ 3 H2O |
| C2F6 | 50,000 | 1200 | n.a. | 97.60 | C2F6 + 2 O2+ 3 H22 CO2 + 6 HF |
| Cl2 | 10,000 | 1 | 1 | 99.99 | stable |
| GeH4 | 4,000 | 0.02 | 0.2 | >99.98 | GeH4 + 2 O2GeO2 + 2 H2O |
| H2 | 125,000 | 0.5 | 5 | >99.99 | 2 H2 + O22 H2O |
| HCl | 3,000 | 1 | 5 | 99.97 | stable |
| NF3 | 50,000 | 5 | 10 | 99.99 | 4 NF3 + 3 O22 N2+ 6 OF2 |
| NH3 | 10,000 | 5 | 25 | 99.95 | 4NH3 + 3 O22 N2+ 6 H2O |
| PH3 | 6,000 | 0.01 | 0.3 | >99.99 | 2 PH3+ 4 O2P2O5+ 3 H2O |
| SF6 | 5,000 | 75 | 1,000 | 98.50 | SF6 + O2
+ 3 H2SO2 + 6 HF |
| SiF4 | 4,000 | 1 | n.a. | 99.98 | SiF4 + O2SiO2 + 2 F2 |
| SiH2Cl2 | 1,000 | 1 | 5 | 99.90 | 2 SiH2Cl2+ 3 O22 SiO2 + 2 H2O + 2 Cl2 |
| SiH4 | 16,000 | 0.5 | 5 | >99.99 | SiH4 + 2 O2SiO2 + 2 H2O |
| Process | Typical Gases | Recommended Scrubber Type | |
| Dry Etch | Metal | Cl2, BCl3, SiCl4, CHF3, CF4, SF6 | SSD or SWB |
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Poly silicon | HBr, Cl2, NF3, SF6 | SSD or SWB |
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Nitride | HBr, CF4, SF6 | SSD or SWB |
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W, Al Oxide | Cl2, SF6, CHF3, CF4, NF3 | SSD or SWB |
| PECVD | BPSG | TEOS, TMP, TMB, N2O, SIH4, B2H6, PH3, C2F6/NF3 | SBW |
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PSG | SiH4, PH3, N2O, TEOS, TMP, C2F6/NF3 | SBW |
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Oxide/Nitride | SiH4, NH3, N2O, C2F6/NF3 | SBW |
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Tungston | WF6, NF3, SiH4 | SBW |
| LPCVD | Nitride | DCS, NH3 | SBW |
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Poly silicon | SiH4 | SBW |
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(doped) TEOS | TEOS, PH3 | SBW |
| Ion Implant | B2H6, BF3, PH3, AsH3, Ar | SSD or SBW | |
| MOCVD | GaAs | H2, AsH3, MO sources | SBW |
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InP | H2, PH3, AsH3, MO sources | SBW |
| GaN | H2, NH3, MO Sources | SBW | |
