Dry etching is usually used for small geometry devices to have more control in shaping the vertical walls. Tetrafluoromethane (CF4) is one of the reactive ions created from chemical dry etching.
What is Tetrafluoromethane Gas?
Tetrafluoromethane (CF4), also known as perfluoromethane, is a colorless, nonflammable, and nontoxic gas. It is chemically inert and has a moderately high global warming potential (GWP = 6,630; Greenhouse gas protocol, Fifth Assessment Report AR5).
Tetrafluoromethane is very stable and has a long atmospheric lifetime of 50,000 years. Although structurally similar to chlorofluorocarbons, tetrafluoromethane does not deplete the ozone layer. This is because the depletion is caused by the chlorine atoms in CFCs, which dissociate when struck by UV radiation. Carbon-fluorine bonds are stronger and less likely to dissociate. It is used as an important component in some ultra-low temperature refrigeration systems and also as a reactive ion etching gas in semiconductor materials processing applications.
Tetrafluoromethane Gas Applications
In semiconductor applications, for example, in reactive ion etching, tetrafluoromethane is the largest volume fluorocarbon gas employed. With a fluorine to carbon ratio of 4:1, carbon tetrafluoride provides the highest concentration of highly reactive trifluoromethyl and fluorine radicals without accompanying hydrogen atoms. As a result, semiconductor material plasma etching processes employing tetrafluoromethane are relatively aggressive with respect to fluorine radical formation. On the other hand, plasmas processes involving tetrafluoromethane provide essentially no fluorocarbon film formation properties. In other applications, tetrafluoromethane can be used as a plasma chamber cleaning gas, an expansion agent for polyolefins and polyurethanes, as a propellant for aerosols, as a fire extinguishing agent, and as a gaseous dielectric insulating medium.
EF Gases is a trusted source when purchasing tetrafluoromethane cylinders because we offer gases of high purity and quality that provide better use applications and superior dimensional and profile control.
- Combined with oxygen to etch polysilicon, silicon dioxide, silicon nitrite, some metals and metal silicides
- Can be combined with halocarbon 116 or used alone to clean wafers and chambers
- Wafer etch processes
- Low-temperature refrigerant (R-14)
- Expansion agent for polyolefins and polyurethanes
- Electronics microfabrication
- Propellant for aerosols
- Fire extinguishing agent
- Gaseous dielectric insulating medium
- Neutron detector
|Purity||Grade 3.5||Grade 4||Grade 4.5||Grade 5|
|Nitrogen||< 400 ppmv||< 60 ppmv||< 30 ppmv||< 5 ppmv|
|Oxygen||< 100 ppmv||<20 ppmv||< 5 ppmv||< 1 ppmv|
|Carbon Monoxide||< 20 ppmv||< 5 ppmv||< 1 ppmv||< 0.5 ppmv|
|Carbon Dioxide||< 10 ppmv||< 5 ppmv||< 1 ppmv||< 2 ppmv|
|Moisture||< 10 ppmv||< 5 ppmv||< 5 ppmv||< 1 ppmv|
|Halocarbon 116||< 1 ppmv|
|Other Halocarbons||< 50 ppmv||< 5 ppmv||< 5 ppmv|
|Hydrocarbons||< 1 ppmv|
|Acidity||< 0.1 ppm/w||< 0.1 ppm/w||< 0.1 ppm/w|
|Chemical & Physical Properties|
|Specific Volume||4.39 cu.ft/lb|
|Pressure @ 70° F||23.5 psig|
|Valve Outlet||CGA 580 CGA 320|
|DOT No.||UN 1982|
|DOT Label||Green, Non-Flammable Gas B|
|Cylinder Size||Fill Weight (lbs)|
FAQs about Tetrafluoromethane
Tetrafluoromethane is very stable due to the strength of C-F bonds with bonding energy of 515 kJ.mol-1. Therefore it is inert to acids and hydroxides influence; however, it reacts explosively with alkali metals. Thermal decomposition produces very toxic gases (carbonyl fluoride, carbon monoxide, and in the presence of water also, corrosive hydrogen fluoride).
Tetrafluoromethane can be widely used in silicon, silica, silicon, phosphorus silicon nitride thin film material such as glass and tungsten etching, in electronic components surface cleaning, solar cell production, laser technology, cryogenic refrigeration, leak test, and more.
Tetrafluoromethane is sometimes used as a low-temperature refrigerant. It is used in circuit board manufacture and manufacture of insulating materials and semiconductors. It is used as a gas etchant and dry/plasma etching.
**Moisture level guaranteed only when Electronic Fluorocarbons prepares the cylinders.
All concentrations are on a mol/mol basis unless otherwise stated.
Product sold on the basis of total impurities. Individual impurities may vary slightly.
*This gas not available for purchase online.