It was introduced in the seventies, mainly for stripping resists. Plasma etching is a form of plasma processing used to fabricate integrated circuits. Ee143 f2010 lecture 14 etching university of california. The etching process is discussed in terms of three basic steps. Thus, many different applications are feasible, for example.
Plasma etching processes for interconnect realization in vlsi. Fundamentals and applications series on semiconductor science and technology 7 sugawara, m. Dry etching is an etching process that does not utilize any liquid chemicals or etchants to remove materials from the wafer, generating only volatile byproducts in the process. A plasma creates ions, and neutral species that are drawn to a biased electrode. Edc plasma plasma discharge zones paschenslaw erf plasma ehighdensity plasmas edrie microloading silicon grass 172005 eel6935 advanced mems spring 2005 instructor. Etching, deposition, and wafer bonding techniques for semiconductor applications.
The plasma source, known as etch species, can be either charged or neutral atoms and radicals. Introduction to plasma etching university of texas at austin. Highly anisotropic using sidewall polymerization techniques, can be selective but less so than plasma etching due higher dc bias and longer mean free path. Pdf plasmaetching processes for ulsi semiconductor circuits. For plasma etching to happen, the chamber has to be under low pressure, less than 100 pa. Plasma etching page 3 introduction ideal etching process substrate film to be etched resist substrate resist prior to etch after etch no process is ideal, some anisotropic plasma etches are close ideal etching is the accurate transfer of the pattern to the underlying film. Ammonium hydroxide nh 4 oh is one hydroxide which is free of alkali metal, but it is really ammonia which is dissolved into water. Mram, as a fast and nonvolatile memory with low power consumption, appears to be one of the suitable candidates for the next memory generation. Plasma etching and the benefits over liquid etching. Dry etching may be accomplished by any of the following. Plasma etching summary plasma has ions and excited species of reactive gases reactive ions are directed to the surface by electric fields chemical reactions take place at the surface and eat away the material sputtering can also etch away material reaction products are removed in gas form dry etching. Etch rate uniformity across wafer key etch variables. Pdf based inductively coupled plasma etching of ganalgan.
The specimen was removed from the epoxy mount, wrapped in platinum wire and immersed in molten koh at 673 k for 10 to 15 sec. Gupta ua cafmff and mint center, the university of alabama and a. Inductivelycoupled plasma reactive ion etching of al o. Microfabrication process of magnetic materials have become increasingly important for magnetic random access memory mram, and patterned media, readwrite heads for data storage, etc. This futureoriented technology allows for modification of a wide range of surfaces. Reactive ion etching is an anisotropic processreactive ion etching is an anisotropic process. Plasma etching was performed using the system shown in figure 2. Plasma etching techniques are typically classed by the configuration of the electrodes. Inductivelycoupled plasma reactive ion etching of al 2 o 3 for write pole applications xiao li, a.
Overview of plasma etch mechanisms il anisotropic plasma etching has two components, chemical etching neutrals and radicals of the plasma and physical bombardment ion assisted etching reactions. Etching characteristics of magnetic materials co, fe, ni. The development of finer semiconductor devices with even thinner layer means that etching systems must process gate materials with high selectivity to extremely thin gate dielectric layer and without etching damage, under precise cd critical dimension control. Worstcase design with mask erosion let be the vertical and lateral etching rates of the mask. Increasing mean free path general increasing anisotropy plasma presswe 112 types of etch processes on a chamber pressure scale. Aln etching rate and selectivity versus the bias power. Plasma etching is a synergistic process of both chemical and physical etching, which makes it distinctive from conventional wet etching. Abstract plasma etching, which is expected to play an important role in the manufacture of semiconductor and other devices requiring fineline lithography, involves using a glow discharge to generate chemically reactive species from relatively inert molecular gases. Etching, deposition, and wafer bonding techniques for semiconductor applications 83 and iedf include the bias voltage vb, the ion density, the gas composition, and the mean free path which also depends on the aforementioned parameters. 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. Plasma cleaning, therefore, is much more than just a cleaning process, it is also a surface. Jun 20, 2012 lam research lam rainbow 4420 lam rainbow 4520 lam rainbow 4620 lam rainbow 4720 duration. In order to generate lowpressure plasma, the gas has to be ionized. Tmah etching of silicon 2 hydroxide etches are generally safe and predictable, but they usually involve an alkali metal which makes them incompatible with mos or cmos processing.
Berkeley ee143 f2010 lecture 15 1 reactive ion etching r ie plasma wafers rf. Download fulltext pdf based inductively coupled plasma etching of ganalgan using photoresist mask article pdf available in ieee transactions on plasma science 409. Introduction of plasma cleaning, surface modification, and etching process plasma cleaning is defined as a process that uses an ionized gas to interact with a substrate in order to remove contamination andor modify its surface. Introduction of plasma much more than just a cleaning. Plasma etching has become a crucial process step for the microelectronics industry, as computer logic and memory circuits require increasingly precise fabrication of finescale patterns in semiconductors, metals, and insulators.
Plasma etching plays an essential role in microelectronic circuit manufacturing. See section 5 for details on people available for contact. During the process, the plasma generates volatile etch products at room temperature from the chemical. It involves a highspeed stream of glow discharge of an appropriate gas mixture being shot in pulses at a sample. Extremely anisotropic, independent of material composition useful in quaternaries. Plasma etching techniques including rie, pe, icp, and drie. Chamber pressure y pressure torr chemical plasma etching. Plasma etching ebook by 9780080924465 rakuten kobo. 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. Inductivelycoupled plasma reactive ion etching of al o for. As a consequence, the etching rate will linearly increase with the bias power. A new microwave plasma etching system using time modulation bias technology overview. Dry etching is a type of plasma etching, wherein the materials are blasted with ions in a gaseous atmosphere, as previously described. Plasma is used in applications where it is important to combine materials or to specifically change their surface properties.
Lecture 10 wet etching and bulk university of utah. Purchase plasma etching processes for interconnect realization in vlsi 1st edition. Plasma etching is widely used for etching nanoscale features because it can produce vertical sidewall profiles with little or no undercut. This anisotropic feature can be further enhanced by allowing the deposition of certain passivating films to occur along vertical sidewalls during the plasma reaction. 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. Introduction of plasma much more than just a cleaning process. Bcl 3 flow rate the etching rate and selectivity display mixed effect with an increase of the a flow rate of bcl 3 as shown in figure 4. In the eighties, plasma etching became a mature technique to etch layers and was introduced in the production of integrated. Scribd is the worlds largest social reading and publishing site.
Plasma etching is a relatively new technique in the fabrication of integrated circuits. Etching with molten koh was performed as outlined in figure 1. Pdf based inductively coupled plasma etching of gan. Ammonium hydroxide nh 4 oh is one hydroxide which is free of alkali metal, but it.
Download fulltext pdf plasmaetching processes for ulsi semiconductor circuits article pdf available in ibm journal of research and development 431. Many of the plasmas used in dry etching are weakly ionized ionization fraction, x i free. The emphasis will be on the fundamental physical and chemical processes that determine the consequences of a reactive gas plasmasurface interaction. Memsii lecture 2 dry etching i university of florida. Etching of the specimens was performed by two methods. Plasma etching processes for interconnect realization in. Sic etching in fluorinebased high density electron cyclo.
Introduction in the early 1960s, at the beginning of modern silicon carbide sic development, sic. Introduction in largescale integrated circuit lsi manufacturing, particles generated in the process equipment, especially in the plasma etcher, cause serious problems such as decreased yield of lsi in massproduction and low machine operating e. 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. Wet chemical etching basics before going into the speci. Lam research lam rainbow 4420 lam rainbow 4520 lam rainbow 4620 lam rainbow 4720 duration.