Plasma etching process pdf

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 small in magnitude and short in duration a plasma is created whenever gases are forced to conduct electric current. A plasma creates ions, and neutral species that are drawn to a biased electrode. The magna sets new standards in several key areas, including faster etch times, lower power usage, and incredible process uniformity not achievable with any. Multivariable oes data analysis for plasma semiconductor. The second stage was a selective etch to secure remaining polysilicon and expose the substrate. One key plasma etching process technology required in sic power device manufacturing, is sic trench etching, which is essential in creating the sic trench. Depending on the gas mixture, a chemical reaction or sputter etch process occurs at the surface of a substrate.

Ee143 f2010 lecture 14 etching university of california. Etching process development of sio etching using inductively. Rie is advantageous over wet etching in that it produces good anisotropy or selectivity where one species is etched much faster than another. Plasma etching is a synergistic process of both chemical and physical etching. The surface of the component is usually etched with a reactive process gas which gives both a chemical and physical effect on the surface. Usyd senior plasma physics lectures 42,534 views 9. The advantage is that the wafer surface is not damaged by accelerated ions. A b m khairul alam etching process development of sio2 etching using inductively coupled plasma, 49 pages university of eastern finland masters degree programme in photonics. Reactive ion etching rie combines best of directionality and selectivity. Setch rate material 1 etch rate material 2 is said to have a selectivity of s for material 1 over material 2. Plasma atomic layer etching using conventional plasma. Plasma etching, a revolutionary extension of the technique of physical sputtering, was introduced to integrated circuit manufacturing as early as. Generally, previous research on oes measurements of plasma etching has largely focused on particular. Dependence of speed of plasma chemical etching of silicon sef 7.

Janne laukkanen abstract the etching characteristics of sio2 have been studied systematically using inductively coupled plasma. Plasmaetching processes for ulsi semiconductor circuits article pdf available in ibm journal of research and development 431. The systems used are very similar in principle to sputtering deposition systems. Wet and dry etching university of california, davis. In plasma systems, ions can be accelerated fast enough so as to ram into the surface, knocking out. It utilizes plasma instead of liquid etchants to remove the materials, which is. Reactive ion etching is an anisotropic processreactive ion etching is an anisotropic process. Plasma based dry etching rf power is used to drive chemical reactions plasma takes place of elevated temperatures or very reactive chemicals types. Plasma emission intensity is monitored at a selected wavelength, without additional illuminating apparatus, and variations in plasma emission intensity are correlated to remaining film thickness, etch rate and uniformity, and etch selectivity. Plasma etching is the removal of plastic, silicon, or other nonmetallic material using plasma created by exciting ions in a gas, usually oxygen and cf4. Etching is used in microfabrication to chemically remove layers from the surface of a wafer during manufacturing. Plasma etching, as the name implies, is a technique of etching in which plasma is used as an etchant instead of strong acids. Plasma etching of deep highaspect ratio features into. Selectivity is the ratio of the etch rates of one materials over the other.

Process termination, when complete wafer dicing has occurred, is achieved by optical endpoint. Etching can be characterized by how much of the process is. Aspect ratio ratio of depth to width of an etched feature. In order to understand the process of plasma etching, it is important to understand the working of a plasma. Request pdf plasma etching of deep highaspect ratio features into silicon carbide this paper reports research performed on developing and optimizing a process recipe for the plasma etching of. Plasma etching, a revolutionary extension of the technique of physical sputtering, was introduced to integrated circuit manufacturing as early as the mid 1960s and more widely in the early 1970s, in an effort to reduce liquid waste disposal in manufacturing and achieve selectivities that were difficult to obtain with wet chemistry. Depending on the gas mixture, a chemical reaction or sputter etch process occurs at the surface of a. Usually, most wet etching processes are isotropic, which are. Plasma etching is a form of plasma processing used to fabricate integrated circuits. Hard mask for etching photoresist oxide rie 1 rie 2 poly to minimize cd distortion, sometimes a twostep rie process is used.

Types of dry etching processes 1 torr 1 mmhg types of etching methods geometry selectivity excitation energy pressure gasvapor etching chemical isotropic very high none. The plasma source, known as etch species, can be either charged ions or neutral atoms and radicals. Using a mask, plasma etching can occur on the exposed areas of the substrate. Plasma etching plasma etching is used to roughen a surface, on the microscopic scale.

A b m khairul alam etching process development of sio2 etching using inductively coupled plasma, 49 pages university of eastern finland masters degree programme in photonics supervisors prof. The reaction that takes place can be done utilizing high kinetic energy of particle beams, chemical reaction or a combination of both. Etching different etching processes are selected depending upon the particular material to be removed. Plasma etching, or reactive ion etching rie, is an important unit operation that is used to remove thin films. Etching is a critically important process module, and every wafer undergoes. It involves a highspeed stream of glow discharge plasma of an appropriate gas mixture being shot in pulses at a sample. Physical etching chemical etching reactive ion etching rie deep reactive ion etching drie plasma plasma partially ionized gas consisting of equal. Prebreaking the cf bonds via the plasma, lowering the net energy required at the surface b.

Achallenge of pale is the high cost of specialized equipment and slow. Dry etching supplants wet wet etching was used exclusively till 1970s etch bias. 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. Generally, previous research on oes measurements of plasma etching has largely focused on particular target applications and has used methods that rely on. More directional anisotropic etching typical rfpowered plasma etch system look just like pecvd or sputtering systems. Sputter etching is essentially rie without reactive ions. Energy and vacuum is needed to maintain plasma gas discharge. Dry etch processes dryetching semiconductor technology. 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. 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. Due to the movable particles of the etch gases the etch profile is isotropic, thus this method is used to remove entire film layers e.

The process can easily be used to etch completely through a silicon substrate, and etch rates are 34 times higher than wet etching. The magna is the worlds first plasma etching system that eliminates the need for cf 4 gases used by pcb manufacturers for plasma. The first stage was a nonselective anisotropic etch to define a desired pattern by etching part. Ee143 f2010 lecture 14 1 etching etching terminology etching considerations for ics wet etching reactive ion etching plasma etching. Plasma atomic layer etching using conventional plasma equipment ankur agarwala. Pdf plasmaetching processes for ulsi semiconductor circuits. Pdf an overview is presented of plasmaetching processes used in the fabrication of ulsi ultralargescale integrated semiconductor circuits. Prebreaking the surface sisi bonds via the ion bombardment, lowering the net energy required at the surface. Plasma is the fourth state of matter, formed by ionizing gas.

The surface of the component is usually etched with a reactive process gas which gives both a. 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. In dry etching, plasmas or etchant gasses remove the substrate material. This mechanism decreases the formation of free electrons and ions. Advantages of plasma etching over wet etching eliminates handling of dangerous acids and solvents. Plasma etching is a synergistic process of both chemical and physical etching, which makes it distinctive from conventional wet etching.

In dry etching, plasmas or etchant gasses remove the substrate. Despite similar failure mechanisms in both sodiumetched and plasmaetched samples, sodium etching produces much higher bond. Pdf plasma chemical etching of silicon optimization of. A plasma is created whenever gases are forced to conduct electric current plasmas generate electrons, reactive neutral species, and ions a plasma is a quasineutral gas of charged and neutral particles. The following are required for successful, production sic trench etching. Introduction to plasma etching willson research group. After the etching process, the porous lowk structures may be exposed to various kinds of postetch plasma processes used to remove the carbonbased mask, decrease the fluorine contamination and prevent the formation of residues on the mask, etc. Introduction to plasma etching university of texas at austin.

A passive, inline method of monitoring film removal or deposition during plasma etching or deposition based on interference phenomena is disclosed. Silicon nitride and silicon etching by ch3fo2 and ch3fco2. Both chemical highly reactive species and ionic very directional species typically play a role. Using the chemistry of the etch to remove material into a solution liquid or gaseous solution sputtering. Magna plasma desmear and etchback system the magna is the worlds first plasma etching system that eliminates the need for cf 4 gases used by pcb manufacturers for plasma processing. Plasma is the fourth state of matter, formed by ionizing gas particles, through radio frequency or heating. More directional anisotropic etching typical rfpowered plasma etch system look just like.

Develops detailed understanding of the deposition and etching of materials by sputtering discharge, and of etching of materials by chemically active discharge. 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. Lecture 1 definition of a plasma, examples, plasma temperature, debye shielding, plasma criteria duration. The addition of reactive gases creates an additional effect of chemical. Optimizing the sic plasma etching process for manufacturing. A polysilicon layer or a single crystal silicon substrate is plasma etched in a two staged process. The wet etching process is either isotropic orientation independent or anisotropic orientation dependent, as shown in fig.

Selectivity the ratio of etch rate of film to etch rate of substrate or mask. Berkeley ee143 f2010 lecture 14 2 etch process figures of merit. 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. Optimizing the sic plasma etching process for manufacturing power devices h. Widely used sin passivation layer found difficult to wet etch hf used but it attacks sio 2. The first stage was a nonselective anisotropic etch to define a desired pattern by etching part way through the polysilicon. Silicon nitride and silicon etching by ch3fo2 and ch3f. Need better definition of small features therefore dry etching, accelerated ions from plasma 2. Need better definition of small features therefore dry etching, accelerated. Rack university of tennessee plasma etching outline plasma vs. Tsuji1 1research and development department, samco inc. One key plasma etching process technology required in sic power device manufacturing, is sic trench etching, which is essential in creating the sic trench mosfet structure. Comparison between chemical etching and plasma etching.

These gases are the main reactant used in an etch process and should be chosen depending on the material being etched. Advantages of plasma etching over wet etching eliminates. Etching is a critically important process module, and every wafer undergoes many etching steps before it is complete. The plasma etching pe is an absolute chemical etch process chemical dry etching, cde. Plasma etching and the benefits over liquid etching.