A plasma etcher, or etching tool, is a tool used in the production of semiconductor devices. It is a highly controllable process that can process a wide variety of materials, including. The surface of the component is usually etched with a reactive process gas which gives both a chemical and physical. It is the purpose of this thesis to investigate the utility of a plasma etching process in the removal of the active metal.
Rie uses chemically reactive plasma to remove material deposited on wafers. Plasma etching is a synergistic process of both chemical and physical etching, which makes it distinctive from conventional wet etching. Fesem micrographs of etched ni thin films at various cl2 concentrations. Ga2o3 has been studied in a bcl3ar chemistry using inductivelycoupledplasma. Plasma etching techniques are typically classed by the configuration of the electrodes.
Conventional deep reactive ion etching drie is a plasma etch process with alternating halfcycles of 1 sietching with sf6 to form gaseous sifx. A plasma creates ions, and neutral species that are drawn to a biased electrode. Economou plasma processing laboratory, department of chemical engineering, university of houston, houston, tx 772044792, usa abstract as microelectronic devices continue to shrink and process requirements become ever more stringent, plasma modeling and simulation. For microelectronics applications, the plasma process affects the film quality as well as device characteristics. Berkeley ee143 f2010 lecture 15 1 reactive ion etching r ie plasma wafers rf. High density plasma etching of nickel thin films using a cl2ar plasma 941 figure 2. Repeatable and stable plasma etching conditions are. The most common plasma etch configurations are reactive ion etch rie, planar etch pe, inductively coupled plasma etch icp etch, or deep reactive ion etch drie etch. The rie technique requires relatively high pressure for etching due to the need for plasma stability at low ionization efficiency. Deposition and etching mechanisms in plasma thin film. Wang, in coatings for biomedical applications, 2012. Plasma rie etching birck nanotechnology center fundamentals and applicationsfundamentals and applications 1. Plasma atomic layer etching using conventional plasma equipment ankur agarwala department of chemical and biomolecular engineering, university of illinois, 600 s. In order to understand the process of plasma etching, it is important to understand the working of a plasma.
Etching is the process of selectively removing mask patterned materials from the wafers surface to create desired patterns on the wafers surface. The ion energies should be t1, where t1 is the threshold for etching the passivated top monolayer. Plasma etching allows exploitation of both chemical and. Plasma etching, as the name implies, is a technique of etching in which plasma is used as an etchant instead of strong acids.
Reactive ion etching systems rie etch process plasma etch. Pdf silicon wafers oxidized and stripped by reactive plasma etching were implanted with 5 kev b, 1. Mechanisms for plasma and reactive ion etchfront roughening. Under appropriate conditions, both rie and plasma etching can. Pdf the effect of reactive plasma etching on the transient. A plasma etcher produces a plasma from a process gas, typically oxygen or a fluorine bearing gas, using a high frequency electric field, typically. During plasma etching, the highly energetic and reactive species produced from a selected process gas, such as o 2 or a fluorine bearing. The emphasis will be on the fundamental physical and chemical processes that determine the consequences of a reactive gas plasma surface interaction. In the plasmaetching mode, the electrons accelerated by the applied rf. Pdf etching characteristics of linbo3 in reactive ion. A silicon wafer is placed in the plasma etcher, and the air is evacuated from the process.
On the other hand the use of oxygen 0v bias plasmas can be used for isotropic surface termination of ch terminated diamond surface. Cf, to the oxygen plasma drastically enhance the polymer etch rate 4,5. The type and ratio of gases used in a plasma etch is chosen depending on the material being etched, the masking material, and the etch stop material. Plasma etching is one of the main applications of plasma treatment and the plasma system known as a plasma etcher is commonly used in production of semiconductor devices. Reactive ion etching systems rie etch process plasma. Highly anisotropic using sidewall polymerization techniques, can be selective but less so than plasma etching due higher dc bias and longer mean free path. Aluminum oxide film prepared by plasma enhanced chemical vapor deposition pecvd is one of the promising candidates for an etch mask or an etch barrier. Modeling and simulation of plasma etching reactors for. Plasma is the fourth state of matter, formed by ionizing gas particles, through radio frequency or heating. For etching results in etch rates that are 10 times greater. Suitable for researchers, process engineers, and graduate students, this book introduces the basic physics and. Rie is a type of dry etching which has different characteristics than wet etching. Plasma atomic layer etching using conventional plasma equipment. Plasma etch is the use of a radio frequency rf excited plasma to produce chemically reactive species from various gases.
Edc plasma plasma discharge zones paschenslaw erf plasma ehighdensity plasmas edrie microloading silicon grass 172005 eel6935 advanced mems spring 2005 instructor. Reactive ion etching of gaas and algaas has been performed by using ccl2f202ar 2 and cc12f2he mixtures 3, while plasma etching at higher pressures than are typically associated with rie has been reported for using ccl4, bcc12, and cl 2 0 2 46. Several approaches to solve the problem of si3n4sio2si etch selectivity were analyzed. Thus, for plasma etching where the substrate is placed on the cathode, the anode area must be larger than that of the cathode. Ee143 f2010 lecture 14 6 3 etching selectivity s wet etching s is controlled by. Results to date indicate that reactive plasma the space between the rf electrode and the ground shield. Plasma etching plays an essential role in microelectronic circuit manufacturing. Particle reduction and control in plasma etching equipment. Plasma based etching in the rie mode generally allows for the most useful tradeoffs. Plasma etching plasma etching is used to roughen a surface, on the microscopic scale. A new concept for spatially divided deep reactive ion etching with. Deep nld plasma etching of fused silica and borosilicate glass. Reactiveion etching rie is an etching technology used in microfabrication. The surface of the component is usually etched with a reactive process gas which gives both a chemical and physical effect on the surface.
High density plasma etching of nickel thin films using a cl. A plasma etcher produces a plasma from a process gas, typically oxygen or a fluorinebearing gas, using a high. Tungsten etching has been studied in audio frequent plasmas with nf3o2 and sf6o2 mixtures. Plasma surface etching plasma surface etching is a type of plasma treatment used to increase the surface area of a material on the microscopic scale. For plasma etching of silicon nitride, usually gases containing fluorine like cf4, nf3, chf3 and sf6 18 are used, in most cases in mixtures. The first day of this course covers plasmaassisted etching phenomena and equipment in a manner that will assist the attendee in understanding and developing plasma etching and rie processes. It is a highly controllable process that can process a wide variety of materials, including semiconductors, dielectrics and some metals. Comparison between different fluorocarbon gases cf4, c2f6, chf3 mixed with ch4 or h2 and influence of the residence time.
In terms of etch rate, chemical, physical and plasma etching fall in the same range. Reactive ion etching rie is a plasma etching technology to fabricate micro and nanostructures. Shkel microsystems laboratory, university of california, irvine, ca, usa, 92697 email. Reactive ion etching rie is a high resolution mechanism for etching materials using reactive gas discharges. Plasma etching techniques including rie, pe, icp, and drie. Weve developed a wide range of solutions for plasma cleaning, plasma etching, reactive ion etching rie, plasma treatment, surface modification, and other facets of plasma processing. Conventionally, use of reactive ion etching rie with bcl3sf6, bcl3sf6n2 or sicl4sf6n2 has been a typical choice for the selective etch process. Barrel sputter etching rie parallel plate plasma etching glow discharge methods downstream etching ecr etching beam methods ion milling reactive ion beam etching ion beam assisted chemical etching ion beam methods dry etching pressure range 0. Economou plasma processing laboratory, department of chemical engineering, university of houston, houston, tx.
Advanced plasma etch chambers are equipped with a lot of knobs for controlling the etch process wafer temperature upper electrode temperature. Fluorinebased plasma etching using reactive ion etching rie is a widely used technique for etching deep structures in silicon, silica and glass. Tailoring gas chemistry for selectivity vs anisotropy. Ideally, the gas mixture will react readily with the material being etched, while reacting minimally with materials that should not be etched, thus achieving high selectivity. The primary difference here is that the noble gas plasma is replaced by a molecular gas plasma similar to that in plasma etching. The most common plasma etch configurations are reactive ion etch rie, planar etch pe, inductively coupled. It involves a highspeed stream of glow discharge of an appropriate gas mixture being shot in pulses at a sample. Plasma plasma is a partially ionized gas composed of equal numbers of positive and negative. Plasma etching and the benefits over liquid etching. During rie etching processes, volatile compounds are formed in interaction of sample surfaces and high. Active metals can be used as a getter pump, removing impurities in ultrapure high vacuum environments.
The influence of etch mode, gas flows, pressure and power. Introduction to plasma etching university of texas at austin. Extremely anisotropic, independent of material composition useful in quaternaries. Plasma etching is a form of plasma processing used to fabricate integrated circuits. Etching characteristics of linbo3 in reactive ion etching and inductively coupled plasma article pdf available in journal of applied physics 1033. Suitable for researchers, process engineers, and graduate students, this book introduces the basic physics and chemistry of electrical discharges and relates them to plasma etching mechanisms. Oxygen plasma etching can be used for anisotropic deep etching of diamond nanostructures by application of high bias in inductively coupled plasma reactive ion etching icprie reactor. During rie etching processes, volatile compounds are formed in interaction of sample surfaces and highenergy ionsradicals generated by lowpressure plasma. Deep nld plasma etching of fused silica and borosilicate glass mohammed j. Deep plasma etching of glass with a silicon shadow mask. The subject matter is therefore well tuned to the needs of workers in the semiconductor industry, although it would also serve as an excellent textbook for a final undergraduate year or postgraduate. A plasma is a quasineutral gas of charged and neutral particles quasineutral means that overall the net charge of the plasma is approximately zero, because fluctuations in charge density in the plasma are. Plasma etching allows exploitation of both chemical and physical processes to remove solid material locally.
Plasma atomic layer etching using conventional plasma. To relieve the difficulties involved with the transportation, storage and handling of these metals, a process is being developed to create a protective coating by removing the active metal component from the surface of a mixture of the active metal and a stable element via immersion in a wet. Due to low ion energy and narrow ion energy distribution, low damage etching and nano structuring can be performed with our icp plasma etching tools simple high rate etching. Reactive ion etching mechanism of plasma enhanced chemically. A series of etching experiments, conducted according to an l9 34 orthogonal array, was carried out on a plasmalab pc5100 reactive ion etcher plasma technologyuk ltd. Reactive ion etching and plasma etching of tungsten sciencedirect. Modeling and simulation of plasma etching reactors for microelectronics demetre j. High density plasma etching of nickel thin films using a. Pdf a survey on the reactive ion etching of silicon in. Material from the surface is etched away, converted to the gas phase and removed by the vacuum system.
Plasma etching is widely used for etching nanoscale features because it can produce vertical sidewall profiles with little or no undercut. The first day of this course covers plasma assisted etching phenomena and equipment in a manner that will assist the attendee in understanding and developing plasma etching and rie processes. The basis of plasmaassisted etching, the main dry etching technique, is explained and plasma system configurations are described such as reactive ion etching. Marking is routinely used by fabricators and manufacturers to etch numbers or letters into a part, indicate where a hole should go, highlight a weld location, and other operations. Plasma is the fourth state of matter, formed by ionizing gas particles, through. Reactive ion etching is an anisotropic processreactive ion etching is an anisotropic process. Energy and vacuum is needed to maintain plasma gas discharge.
Reactive ion etching systems rie plasma etching samco inc. Weve developed a wide range of solutions for plasma cleaning, plasma etching, reactive ion etching rie. Rack university of tennessee plasma etching outline plasma vs. Plasma etching was used to remove si3n4, thereby isolating the glass phase for chemical analysis in the transmission electron microscope. Plasma etching is commonly employed in the chemical etching process of wafer fabrication because of its low cost and good control of etching profile and uniformity. An alternative plasma etching method is reactive ion etching rie, which employs apparatus similar to that for sputter etching shown in figure 6. Reactive ion etching rie is an etching technology used in microfabrication. The surface of the component is etched with a reactive process gas. Memsii lecture 2 dry etching i university of florida. For plasma etching of silicon nitride, usually gases containing fluorine like cf4, nf3, chf3 and sf6 18 are used, in most cases in mixtures with other gases as o2, n2, h2, ar and no. Ee143 f2010 lecture 14 etching university of california. A decision tree for the selection of a suitable etchant gas was developed and.
Simultaneously, if a plasma is observed, start a stopwatch. The volatile compounds are removed from the sample surfaces, and isotropic or anisotropic. The plasma is generated under low pressure by an electromagnetic field. The second step is exposure of the passivated layer to an etching plasma to remove. The reactive plasma is exposed to the wafer surface and etches away theread more. Turn the rf level knob on the chamber to the \hi setting and make sure there is a light purplepink color in the chamber indicating a plasma. Ideally, the gas mixture will react readily with the. Otherwise, increase the pressure slightly with the oxygen controls and try to initiate the plasma again.
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