Exhaust Gas Purification by Burner-Washer Combination

This type of exhaust gas treatment system consists of several parts. In the first step, soluble and corrosive gases are removed by a washer to protect the downstream burner. The SWB series of scrubbers includes this option; the SBW series does not. In addition to these burner-washer systems, we offer other types of scrubbers for different processes, which you can find on our scrubber product overview page.

Installing such a washer is always recommended when the exhaust or ventilation air contains strongly corrosive hydrogen halides like HCl or HBr, or when the exhaust contains metal halides such as tungsten hexafluoride WF6.

The second purification step is the core part of the scrubber: the electrically heated combustion chamber where thermal decomposition of the non-water-soluble components of the exhaust gas takes place. The gas is heated and oxygen is added to oxidize the toxic components. The temperature distribution in this section is very important. It must reach a minimum value to remove all toxic components. During the decomposition of these substances a significant amount of dust is usually produced. Sometimes soluble and corrosive gases are released again. This dust must be removed in the following steps.

After passing through a cyclone, the gas reaches a second washer. The water is circulated via a recirculation tank, which can optionally be cooled. Remaining moisture after this step is removed in a dehumidifier.

Exhaust gas treatment with combustion and washer

Several different types of hot-wet scrubbers can be supplied by SemiAn, which are listed in the table below. All essential parts are made of stainless steel, the reactor itself is made of Inconel and the circulation pump is Teflon-coated. The reactor is equipped with a heater that can be adapted to customer requirements. It can be cleaned automatically. Control is via a PLC and a heater power controller. Operation and visualization are done via a TFT monitor. An optional central control unit is available that shows the status of all connected gas cleaners. A multitude of safety functions, interlocks and leak control systems are installed. The plant footprint has been minimized to keep the operating costs as low as possible.

Overview of the hot-wet exhaust cleaner types

Our gas scrubbers are specifically designed to reliably and efficiently treat industrial exhaust gases. They help reduce emissions and comply with regulatory requirements. By using state-of-the-art technologies, pollutants in the exhaust streams are removed or converted into harmless compounds.

Below you will find a table with a selection of typical exhaust gases and the corresponding methods with which they can be treated. This gives you a practical overview of the performance of our systems.

MIDAS-I

The MIDAS-I scrubber combines gas burner technology with wet cleaning and offers efficient treatment of up to 200 SLM of process gases containing CFCs.

Specification
Technical features Product data
Gas inlet NW40, 1-4 PORT
Gas outlet NW63, 1 PORT / -25 to -75 mmH2O
Cabinet exhaust Ø 150 mm FLANGE / -50 to -125 mmH2O
Electrical power consumption 2 kW
Voltage / phase 208 V / 2‑50/60 Hz, 10 A
LNG Max. 65 SLM; Max. 500 mmAq; 3/4" BRASS LOK FITTING
CDA (compressed air) Max. 200 SLM; 2-3 Kgf/cm² (2-3 bar); 1/4" BRASS LOK FITTING
Tap water Max. 8 SLM; 2-3 Kgf/cm² (2-3 bar); 1/2" BRASS LOK FITTING
N₂ (nitrogen) Max. 60 SLM; 4-6 Kgf/cm² (4-6 bar); 1/4" BRASS LOK FITTING
Wastewater drain 3/4" PVC UNION CONNECTION
Dimensions 1050 (W) × 880 (D) × 1980 (H) mm
Weight 460 kg
Certification CE
Application FDP, R&D, Semi
MIDAS-I scrubber

SemiAn Burn-Wet Scrubber SWB 200

Exhaust cleaner with inlet washer for thermal decomposition and oxidation of toxic components. The exhaust cleaning is carried out in three steps: washing out soluble components, pyrophoric decomposition of toxic or flammable fractions, and post-cleaning with a washer and a water circulation system. This plant type can be used to clean exhaust gases from PE-CVD (semiconductor and LCD manufacturing), LP-CVD, and AP-CVD systems as well as exhaust gases from MO-CVD reactors (optoelectronics).

Specification
Technical features Product data
Gas volume 200 - 400 SLM
Heater temperature 800 - 850 °C
Power consumption 10 kW
Dimensions (W×D×H) 800 × 850 × 2000 mm
Weight 450 kg
Certification CE
Wastewater neutralization system Available
SWB200 scrubber

SemiAn Burn-Wet Scrubber SBW 200-S

Exhaust cleaner for thermal decomposition and oxidation of toxic components in combination with a washer for separating soluble gas fractions and a water circulation system. This plant type is suitable for cleaning exhaust gases from ion implanters, PE-CVD, LP-CVD and AP-CVD systems as well as exhaust gases from MO-CVD reactors (optoelectronics).

In addition to the standard version of the SBW-200, there is also a special model equipped with a plasma burner, specifically designed for the decomposition of chlorofluorocarbons (CFCs). Further details can be found here.

Specification
Technical features Product data
Gas inlet NW40 flange, 1-3 connections
Gas outlet NW63 flange, 1 connection / -25 to -75 mmH2O
Cabinet exhaust Diameter 150 mm flange
Electrical power consumption Max. 7.5 kW
Voltage / Phase 208-220 V / 3 Phase, 60 Hz, 30 A
CDA (compressed air) Max. 200 SLM; 2-3 Kgf/cm²; 3/8" lok fitting
Tap water Max. 6-8 SLM; 2-3 Kgf/cm²; 3/8" lok fitting
Cooling water in/out Max. 12-16 SLM; 2-3 Kgf/cm²; 1/2" lok fitting
N₂ (nitrogen) Max. 60 SLM; 4-6 Kgf/cm²; 1/4" lok fitting
Dimensions 1800 (W) × 900 (D) × 1800 (H) mm
Weight 560 kg
Certification CE
Application R&D
SBW200 scrubber

SemiAn Burn-Wet Scrubber SBW III-202-S

Large version of the exhaust cleaner, consisting of several parallel thermal decomposition units for oxidation of toxic components followed by wet washing. The exhaust cleaning is carried out in two steps: pyrophoric decomposition of toxic or flammable fractions and post-cleaning with a washer and a water circulation system. This type of plant is preferred for cleaning exhaust gases in LCD production for PE-CVD, for exhaust gases from MO-CVD reactors in optoelectronics as well as for exhaust gases from epitaxy reactors.

Specification
Technical features Product data
Heater chamber temperature 800 - 850 °C
Inlet connection ISO 63 flange, 1 connection
Outlet connection ISO 200 flange, 1 connection / -25 to -75 mmH2O
Cabinet exhaust connection Diameter 100 mm flange / -25 to -125 mmH2O
Wastewater outlet connection 1/2" lok fitting
Electrical power 20 kW
Voltage / Frequency / Phase 208 V / 50/60 Hz / 3 Phase, nominal current 75 A
Current at full load 55 A
Operating current 30-40 A
Cooling water in/out 2-3 Kgf/cm²; 8-12 SLM; 3/8" lok fitting
CDA (compressed air) 2-3 Kgf/cm²; max. 750 SLM; 1" lok fitting
Nitrogen 4-6 Kgf/cm²; max. 100 SLM; 1/4" lok fitting
Exhaust gas sampling connection 1/4" lok fitting
Dimensions 1800 (W) × 900 (D) × 2000 (H) mm
Application Si-C, MO-CVD, PE-CVD
Certification CE
Weight 1200 kg
SBW 202 scrubber

Measurement data

The following chemicals can be removed from exhaust gases using this method. The table shows the maximum inlet concentration and the minimum outlet concentration of the pollutants, as well as their MAK (maximum workplace concentration; English: TLV). The reaction taking place in the reactor is described. In the washer, soluble gases such as HF or HCl formed during oxidation are removed. Produced chlorine gas is converted in the washer to hydrochloric acid HCl and hypochlorous acid.

Gas Max. inlet concentration (ppm) Min. outlet concentration (ppm) MAK (ppm) Efficiency (%) Chemical reaction in the burner
AsH3 AsH3 5,000 0.01 0.05 >99.99 2 AsH3 + 3 O2 → As2O3 + 3 H2O
B2H6 B2H6 2,500 0.01 0.1 >99.99 B2H6 + 3 O2 → B2O3 + 3 H2O
C2F6 C2F6 50,000 1200 n.a. 97.60 C2F6 + 2 O2 + 3 H2 → 2 CO2 + 6 HF
Cl2 Cl2 10,000 1 1 99.99 stable
GeH4 GeH4 4,000 0.02 0.2 >99.98 GeH4 + 2 O2 → GeO2 + 2 H2O
H2 H2 125,000 0.5 5 >99.99 2 H2 + O2 → 2 H2O
HCl HCl 3,000 1 5 99.97 stable
NF3 NF3 50,000 5 10 99.99 4 NF3 + 3 O2 → 2 N2 + 6 OF2
NH3 NH3 10,000 5 25 99.95 4 NH3 + 3 O2 → 2 N2 + 6 H2O
PH3 PH3 6,000 0.01 0.3 >99.99 2 PH3 + 4 O2 → P2O5 + 3 H2O
SF6 SF6 5,000 75 1,000 98.50 SF6 + O2 + 3 H2 → SO2 + 6 HF
SiF4 SiF4 4,000 1 n.a. 99.98 SiF4 + O2 → SiO2 + 2 F2
SiH2Cl2 SiH2Cl2 1,000 1 5 99.90 2 SiH2Cl2 + 3 O2 → 2 SiO2 + 2 H2O + 2 Cl2
SiH4 SiH4 16,000 0.5 5 >99.99 SiH4 + 2 O2 → SiO2 + 2 H2O

Recommended scrubbers

The following list shows the most common processes in the semiconductor industry that require exhaust gas cleaners. Dry etchers are produced, for example, by Applied Materials or Lam Research. Typical layers that need etching are metal layers, polysilicon layers, nitride layers, oxide layers and tungsten layers. PECVD is used to produce special films at low temperatures such as oxides, PSG and BPSG as well as tungsten films. LPCVD is typically performed today in vertical furnaces, e.g. by JTEKT Thermo Systems. Deposition of nitrides, polysilicon and TEOS are typical processes in this area. Ion implanters also produce toxic exhaust gases that must be decomposed. MOCVD is mainly used in the production of compound semiconductors. A well-known manufacturer of these systems is Aixtron.

In some cases special measures must be taken to prevent reactor clogging by dust.

Alternative exhaust gas cleaning methods are wet cleaning and chemisorption. An overview of all cleaning systems can be found on our SemiAn exhaust cleaner page.

Process / material Typical gas Recommended scrubber type
Dry etching metals Cl2, BCl3, SiCl4, CHF3, CF4, SF6 SSD or SWB
Dry etching polysilicon HBr, Cl2, NF3, SF6 SSD or SWB
Dry etching nitride HBr, CF4, SF6 SSD or SWB
Dry etching W, Al oxide Cl2, SF6, CHF3, CF4, NF3 SSD or SWB
PECVD BPSG TEOS, TMP, TMB, N2O, SiH4, B2H6, PH3, C2F6/NF3 SBW
PECVD PSG SiH4, PH3, N2O, TEOS, TMP, C2F6/NF3 SBW
PECVD Oxide/Nitride SiH4, NH3, N2O, C2F6/NF3 SBW
PECVD Tungsten WF6, NF3, SiH4 SBW
LPCVD Nitride DCS, NH3 SBW
LPCVD polysilicon SiH4 SBW
LPCVD (doped) TEOS TEOS, PH3 SBW
Ion implanters B2H6, BF3, PH3, AsH3, Ar SSD or SBW
MOCVD GaAs H2, AsH3, MO sources SBW
MOCVD InP H2, PH3, AsH3, MO sources SBW
MOCVD GaN H2, NH3, MO sources SBW