In this framework, an understanding of the plasma chemistry mechanisms involved in various gas systems is important for future progress. A selfconsistent, onedimensional simulator for the physics and chemistry of radio frequency rf plasmas was developed and applied for ch4 and cf4. In device fabrication, organic materials are always present because resist masks are the primary method of pattern transfer. Publishers pdf, also known as version of record includes final page, issue. Abstract the chemistry of the dry etching titanium thin films has been investigated in fluorinated and chlorinated environments. Then in the early 1970s, both plasma ashing and plasma isotropic etching technology were successfully used in semiconductor manufacturing companies. Electronic properties of ntype carbon nanotubes prepared by. Plasma chemistry of fluorocarbon rf discharges used for dry etching. Selective plasma etching of polymeric substrates for.
The simulator consists of a fluid model for the discharge physics, a commercial boltzmann equation solver for calculations of electron energy distribution function eedf, a generalized plasma. Inflow rates are mapped for the respective components of the input recipe to find settings that provide both high nitride etch rates and high selectivity towards the sin material. Plasma treatment of a polymeric surface could involve at least three major mechanisms. The dependence of the etch rate of polyimide on the relative concentrations of these two gases was compared with data from optical emission spectra, mass spectra, and x. Chemical dry etching of silicon nitride and silicon dioxide. Ionized means that at least one electron is not bound to an atom or molecule, converting.
Cambridge core plasma physics and fusion physics plasma chemistry by alexander fridman. The chemical etching part of undoped polysilicon etch rates is linearly proportional to the ground state fluorine population and the ion bombardment part is proportional to the dc. Mechanisms of hydrophobization of polymeric composites. Silicon nitride and silicon etching by ch3fo2 and ch3f.
Observations process the process used to remove the su8 photoresist is a long plasma etch using cf 4 at 300 mtorr in a 300 watt plasma, using a fomblin charged rotary vacuum pump. Polymerization of fluorocarbons in reactive ion etching. The increase in o atom number density in the plasma with addition of cf4. An introduction to nonequilibrium plasmas at atmospheric pressure sander nijdam, eddie van veldhuizen, peter bruggeman, and ute ebert 1. The dominant chemical reaction kinetics occurring in the plasma environment are studied by small periodic power modulation and analyzed using transfer functions. Plasma as the fourth state of matter although the term chemistry in the title of the book does not require a special introduction, the term plasma probably does. Characterization of local chemical structures using raman spectroscopy reveals that the cvd graphene layer is essentially undamaged under the cf4 h2 plasma and dehydrogenation. The chemistry incharged species are formed in a plasma discharge. This unique book provides a fundamental introduction to all aspects of modern plasma chemistry. Plasma is also found in neon lights, plasma displays, arc welding torches, and tesla coils. Introduction to theoretical and applied plasma chemistry. The chemical etching is shown to be enhanced by ion bombardment of the reacting surface.
Cf4chf3h2cl2o2hbr plasmas under different gas mixing ratios. A chemical downstream etching cde that is selective to silicon nitrides sin over silicon oxides sio uses at least one of a ch 3 f cf 4 o 2 recipe and a ch 2 f 2 cf 4 o 2 recipe. Plasma rie etching birck nanotechnology center fundamentals and applicationsfundamentals and applications 1. Electronic properties of ntype carbon nanotubes prepared. In cf4 o2 plasma the hard native stoichiometric oxide, tio2, always present on the titanium surface, results in a nonreproducible induction time. Plasma chemistry by alexander fridman cambridge core. Us5786276a selective plasma etching of silicon nitride.
Rfplasmabased dry etching a plasma is fully or partially ionized gas composed of equal numbers of positive and negative charges and a different number of unionized molecules. Evaluation of cf4 plasma chemistry by power modulation. Etching process development of sio etching using inductively. Polymerization of fluorocarbons in reactive ion etching plasmas. Optical emission analysis of cf4chf3ar plasma etch of oxide. Compared to the wet chemical etching, plasma etching is capable of controlled and precise etching at very small scales 10 nm. Tetrafluoromethane is a useful refrigerant but also a potent greenhouse gas. Chemical dry etching of silicon nitride and silicon dioxide using cf4 o2n2 gas mixtures b. A model is proposed whereby silicon is etched by chemical reaction with free fluorine to produce a volatile species, and also by physical sputtering. Plasma activation or plasma functionalization is a method of surface modification employing plasma processing, which improves surface adhesion properties of many materials including metals, glass, ceramics, a broad range of polymers and textiles and even natural materials such as wood and seeds. Third, plasma etching process can be completely automatized. Tetrafluoromethane, also known as carbon tetrafluoride or r14, is the simplest fluorocarbon c f 4. Oehrleinb department of physics, the university of albany, state university of new york, 1400 washington avenue. Chemistry of titanium dry etching in fluorinated and.
Numerical study of the plasma chemistry in inductively coupled sf6 and sf6ar plasmas used for deep silicon etching applications m mao, yn wang and a bogaertspulsed plasma etching for semiconductor demetre j economourecent citations a global model study of low pressure high density cf. A plasma is produced when an electric field of sufficient magnitude is applied to a gas, causing the gas to break down and become ionized. In plasma processing, the plasma is used as a chemical reactor providing the. O 2 mixtures has been studied as a function of feed.
Therefore most emphasis has been put on understanding the ion and radical kinetics, while. The book describes mechanisms and kinetics of chemical processes in plasma, plasma statistics, thermodynamics, fluid mechanics, and electrodynamics, as well as all major electric discharges applied in plasma chemistry. It can also be classified as a haloalkane or halomethane. F atoms in sf6 or c and f atoms in cf4 are higher than the binding energies between the n and the f atoms in nf. Recently, we reported a comparative study of ch 3fo 2 and ch 3fco 2 discharges, sustained in a compact inductively coupled plasma icp reactor. The book describes mechanisms and kinetics of chemical processes in plasma, plasma statistics, thermodynamics. The mechanisms for the reactive ion etching of silicon by cf4 plasma are investigated. Under prolonged exposure to fire or heat the containers may rupture violently and rocket. Tetrafluoromethane is a colorless nonflammable gas. Surface contamination and damage from cf 4 and sf 6. Selective plasma etching of polymeric substrates for advanced.
O2 gas phase during hollow cathode reactive ion etching plasma. The degree of amino functionalization is dependent on the degree of initial fluorination rather than oxygen or carbon defects. The surface chemistry of plasma fluorinated vertically aligned carbon nanotubes vcnt is correlated to the cf4 plasma chemical composition. Aug 21, 2017 the surface chemistry of plasma fluorinated vertically aligned carbon nanotubes vcnt is correlated to the cf4 plasma chemical composition. Reaction at both ends of 1,2diaminoethane was observed to increase with fluorine content. The increase in o atom number density in the plasma with. A model is proposed whereby silicon is etched by chemical reaction with free fluorine to produce a volatile sp. Singlewalled carbon nanotubes swnts have been fluorinated by cf4 plasma exposure and further functionalized with 1,2diaminoethane. Plasma chemistry this unique book provides a fundamental introduction to all aspects of modern plasma chemistry. This etching process, together with a model for cracking cf 4. For this, experimental measurements were made by mass spectrometry. The maximum etch rate of ymno3 thin films was 300 amin for no cf4 add to the cl2ar gas plasma, an rf power of 800 w, a dc bias voltage of 200 v, a chamber pressure of 15 mtorr, and a substrate. In cf4o2 plasma the hard native stoichiometric oxide, tio2, always present on the titanium surface, results in a nonreproducible induction time.
Plasma etching, referred many times as plasma chemical etching or dry etching, of both organic and inorganic materials was reported for material fabrication in multidisciplinary applications. This etching process, together with a model for cracking cf 4 in the. Consequently, exothermic processes during the plasmasurface interactions are another important factor which influences the surface chemistry and etching rate of the material. A comparative study of cf4o2ar and c4f8o2ar plasmas for dry. On the relationships between plasma chemistry, etching. It was found that higher etch rates with lower plasma induced dc bias can be achieved with sf6 plasma relative to cf4 plasma and that this correlates with higher atomic. Chemical dry etching of silicon nitride and silicon. Thus a process run with a photoresist mask will have a different etch rate and profile than a process run with a oxide mask. Natural examples of plasma include lightning the aurora, the ionosphere, st. While not often seen on earth, plasma is the most abundant form of matter in the universe excluding perhaps dark matter. This can be done by chemical reaction, physical removal of material or a combination of both. A model of the chemical processes occurring in cf 4o 2 discharges. Multifold study of volume plasma chemistry in arcf4 and ar. Heres a schematic of a chamber where plasma etching would occur.
This model calculates the plasma characteristics by combining a monte carlo method for the electrons and a fluid simulation for the heavy plasma species. Two reactive ion etchants, cf4 and sf6, have been compared in terms of plasma characteristics, silicon oxide etch characteristics, extent of rie damage, and formation of barrier layers on a gaas surface after oxide etch. A reaction set describing the complete plasma chemistry is presented and discussed. The established cf4 h2 plasma processing generates, however, cracks along the grain boundaries in cvd graphene, which is responsible for the unusual transport properties. Us5786276a selective plasma etching of silicon nitride in. Chemistry studies of sf6cf4, sf6o2 and cf4o2 gas phase during hollow cathode reactive ion etching plasma l. From measurements of optical emission and silicon etch rate, we are able to separate contributions due to the chemical etching and the ion. A comparative study of ch4 and cf4 rf discharges using a. Chemistry studies of sf6 cf4, sf6o2 and cf4 o2 gas phase during hollow cathode reactive ion etching plasma l. And most importantly, rie is attractive because of its ability to etch anisotropically at relatively low temperatures 1.
O2 mixtures has been studied as a function of feed. The chemical etching part of undoped polysilicon etch rates is linearly proportional to the ground state fluorine population and the ion bombardment part is. Reduced reaction set for the modeling of neutral species. The mechanisms for the reactive ion etching of silicon by cf 4 plasma are investigated. The results obtained via ftir and mass spectrometry are combined with the xps and raman analysis of the sample surface showing the dependence on different plasma parameters power, time and distance from. Ar cf4 plasma shuxia zhao, fei gao, younian wang et al. Gas phase and surface phenomena responsible for etching polyimide in o2cf4 rf plasmas have been investigated. Conversion of cf 4 to stable products co, co 2, cof 2, and sif 4 and the concentration of free f atoms f in the plasma were measured using a number of. Pdf in this work the chemistry of cf4 capacitive plasma is studied.
Specifically we present in this paper our recommended electroninteraction cross sections for cf 4, chf 3, c 2 f 6, and c 3 f 8. Fluorination of vertically aligned carbon nanotubes. Plasma functionalization also refers to the introduction of functional. On the plasmaphysics of plasmaetching pure and applied chemistry. Multifold study of volume plasma chemistry in ar cf 4 and archf 3 ccp discharges o v proshina1, t v rakhimova1, a i zotovich1,2, d v lopaev1, s m zyryanov1,2 and a t rakhimov1 1skobeltsyn institute of nuclear physics, lomonosov moscow state university, russia 2faculty of physics, lomonosov moscow state university, russia email.
Chemical dry etching of silicon nitride and silicon dioxide using cf4o2n2 gas mixtures b. Cf4, c2f6, c3f8, and c3f6based plasmas was performed using spectroscopic and mass spectrometric techniques. It has a very high bond strength due to the nature of the carbonfluorine bond. Pdf fluorination of vertically aligned carbon nanotubes. The continuous exposure to plasma reactive species induces functionalization and etching on the surface, which decides the surface morphology and surface chemistry. Electron interactions with plasma processing gases. Arcf4 plasma shuxia zhao, fei gao, younian wang et al. Cf4 plasma etching of materials used in microelectronics. Fluorine cold plasmas produced by an electrical discharge in sf6, cf4, chf3 or. Plasma is an ionized gas, a distinct fourth state of matter. The plasma etching of silicon and silicon dioxide in cf 4.
Initially, adsorption of these species occurs depending. Cf4h2 plasma cleaning of graphene regenerates electronic. Rie plasma exhaust chemistry for su8 ashing with cf4. To study the gas phase chemistry of a lowpressure highdensity cf 4 chf 3 h 2 cl 2 o 2 hbr plasma, we apply the hybrid plasma equipment model hpem, developed by kushner.
Surface contamination and damage from cf 4 and sf 6 reactive. Tetrafluoromethane is a fluorocarbon and a member of fluoromethanes. Pdf study of cf4 capacitive plasma chemistry through mass. An oxygen deficient plasma ashing process for a downstream plasma ashing device which includes flowing a plasma gas composition of a hydrogen bearing gas, an oxygen source and a cf4 andor c2f6 andor nf3 gas into a reaction chamber 20 and generating a plasma therein to form reactive species to react with photoresist and post etch residues on. Aug 12, 2008 the plasma etching of silicon and silicon dioxide in cf4. Analysis of the etching mechanisms of tungsten in fluorine. Later in 1971, he revealed and patent the experiment of plasma etching of silicon using cf4 gas 3.
Silicon nitride and silicon etching by ch3fo2 and ch3fco2. This paper investigates the chemistry of this process and identifies the effluent and the liquid found in the exhaust line. Plasma chemical behaviour of reactants and reaction. It was found that higher etch rates with lower plasmainduced dc bias can be achieved with sf6 plasma relative to cf4 plasma and that this. The effect of cf4 addition on ru etching with inductively. Tailoring gas chemistry for selectivity vs anisotropy. Removal means that the atoms move from a solid phase to a mobile gas phase.
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