Alan doolittle wet chemical general increasing anisotropy some wet and plasma chemistries can have high anisotropy by using the chemistry to etch preferred crystalline planes. Petersburg, fl 33716 usa 2on semiconductor, 5005 e. We specialize in studying etch processes of nonconventional thinfilm materials such as copper, indium tin oxide, metal oxides, asi. Plasma etching is an alternative approach for patterning crosslinked su8.
Ee143 f2010 lecture 14 etching university of california. An etch system shapes the thin film into a desired patterns using liquid chemicals, reaction gases or ion chemical reaction. The plasma produced by the mixture of fluoride and argon sf 6 ar was applied for the dry etching of aln films. Dry etching technology for semiconductors springerlink. Wafer dicing using dry etching on standard tapes and frames. Instead, it uses gas or physical processes to etch, or create small cut channels, in the material. Reactive ion etching rie is a plasma etching technology to fabricate micro and nanostructures. During rie etching processes, volatile compounds are formed in interaction of sample surfaces and highenergy ionsradicals generated by lowpressure plasma. Memsii lecture 2 dry etching i university of florida.
Total flow was 75 seem, pressure was 200 mtorr, and the power was 50 w. Need better definition of small features therefore dry etching, accelerated ions from plasma 2. Reactive ion etching rie we are interested in understanding the plasma etching mechanism, which includes plasma phase chemistry, plasmasurface reactions, and surface reactions. In order to use this technology for sidewall gate process, an important issue is to achieve a high etching selectivity between sinx and siox. Dry etching was initially focused on mesa structures where high etch rates, anisotropic pro. Dry etching of aln films using the plasma generated by.
Difference between anisotropic and isotropic wet etching. Power, at 25 khz frequency, is ap plied at the lower electrode leaving the upper electrode grounded in the rie mode, or at the upper electrode leaving the lower electrode floating in a pe mode. Will attack organics, and destroy photoresist quickly will form co and co2 and thus reduce fc. Dry etching supplants wet wet etching was used exclusively till 1970s etch bias. Dry etching may be accomplished by any of the following. Dry etch processes dryetching semiconductor technology. Plasma etching, dry etching and reactive ion etching rie all describe processing techniques that have in common the fourth state of matter. The plasma etching pe is an absolute chemical etch process chemical dry etching, cde. Low damage etching is most important for critical layer etching, such as silicon nitride sin and gaasalgaasingap frontside etching when the transistor structure is being fabricated. All samples used for etch rate determination were etched for 60 min while the cf4o2 ratio, total gas pressure. Chemical dry etching of silicon nitride and silicon dioxide using cf4o2n2 gas mixtures b. Led apx300 contributes to high productivity of gan etching by low damage and high rate processing apx300 contributes to high brightness by pss processing.
Samco offers reliable release etching solutions using xenon difluoride xef 2. 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. Wet and dry etching atmosphere, bath vacuum chamber environment and equipment anisotropic isotropic except for etching crystalline materials directionality 1 high cost, hard to implement 2 low throughput 3 poor selectivity 4 potential radiation damage 1 inadequate for defining feature size pdf available in journal of micromechanics and microengineering 353219. Dry etching experiments were performed in an oxford plasma technology mp 80 parallel plate reactor equipped for reactive ion etching. Fluorocarbon compounds, such as c 2f 6 and cf 4, have been used as rie. Hydrogen bromide hbr has often been used to dry etch siliconbased devices because of its high selectivity versus oxide, and high aspect ratio of the pro. This has allowed for a substantial improvement in the etch, increasing yield and enabling the release of smaller and complex devices. Plasma etching of aluminium using bcl3 cl2 mixtures. Analysis of the etching mechanisms of tungsten in fluorine. Dry etching alone would have taken 5 h, and wet etching alone would produce severe undercutting. Wafer dicing using dry etching on standard tapes and frames david lishan1, thierry lazerand1, kenneth mackenzie1, david paysvolard1, linnell martinez1, gordy grivna2, jason doub2, ted tessier3, guy burgess3 1plasmatherm llc, 10050 16th st. An etch system is used in manufacturing lines for semiconductors and other electronic devices. In wafer fabrication, etching refers to a process by which material is removed from the wafer, i.
In this etching mode, the ion bombardment does increase the etch rate considerably. Edc plasma plasma discharge zones paschenslaw erf plasma ehighdensity plasmas edrie microloading silicon grass 172005 eel6935 advanced mems spring 2005 instructor. In the past few years, many research groups contributed to the development of dry plasma etching approaches. An investigation into the patterns of the process, in elementnaya baza mikroi nanoelektroniki. Etching issues selectivity selectivity is the ratio of the etch rate of the target material being etched to the etch rate of other materials chemical etches are generally more selective than plasma etches selectivity to masking material and to etchstop is important mask target etch stop dry etching overview what is dry etching. This book is a musthave reference to dry etching technology for semiconductors, which will enable engineers to develop new etching processes for further miniaturization and integration of semiconductor integrated circuits.
An important consideration in mmic device fabrication is device damage induced during dry etching. Memsii lecture 3 dry etching ii university of florida. Worstcase design with mask erosion let be the vertical and lateral etching rates of the mask. See more ideas about printmaking, drypoint etching and etching prints. With dry etching it is possible etch almost straight down without undercutting, which provides much higher resolution. Numerous dry and wet etchants have been reported in the etch ing of silicon for various applications 15,16. Experimental analysis shows that pure oxygen plasmas etch su8 only very slowly, while adding even a small amount of sf6 can dramatically increase the etching rate. Dry etching is one of two major etching processes used in microelectronics and some semiconductor processing. The effects of the bias voltage and the plasma component on the etching results were investigated. A plasma is struck in the gas mixture using an rf power source, breaking the gas molecules into ions. Pdf patterning pdms using a combination of wet and dry etching. Jun 04, 2015 dry etching using vapor phase processes was developed as a means of moving existing wet etching processes into the vapor phase to improve performance and material compatibility. The advantage is that the wafer surface is not damaged by accelerated ions. Dry etching is the removal of plastic or other semiconductor material using plasma as opposed to chemical treatment.
Chemical dry etching of silicon nitride and silicon dioxide. Angela makie nakazawa, patrick verdonck lsipeeepusp, av. This figure shows that the etch rates increase as ex. Highly anisotropic using sidewall polymerization techniques, can be selective but less so than plasma etching due higher dc bias and longer mean free path. Plasma based dry etching rf power is used to drive chemical reactions plasma takes place of elevated temperatures or very reactive chemicals types. The aluminium oxide breakthrough time was mainly dependent. A dry etching method for removing or patterning polymerised su8 potoresist, based on plasma etching with a mixture of o2 and sf6, has been optimised by the taguchi method. Dry etching is used in conjunction with photolithographic techniques to attack certain areas of a semiconductor surface in order to form recesses in material, such as contact holes which are contacts to the underlying semiconductor substrate or via holes which are holes that are formed to provide an interconnect path between conductive layers in the layered semiconductor. Dry etching is preferred in modern, very largescale integration vlsi processes because it can be more precisely controlled by adjusting parameters such as gas pressure, temperature, and electric field distribution. Very high etching rate up to 140 nmmin have been observed. Widely used sin passivation layer found difficult to wet etch hf used but it attacks sio 2. The plasma state describes a condition where one or more gases are. Etching is used in microfabrication to chemically remove layers from the surface of a wafer during manufacturing.
For many etch steps, part of the wafer is protected from the etchant by a masking material which resists etching. Unlike wet etching, dry etching does not submerge the material to be etched into liquid chemicals. Etch rate also depends on the sample size and percentage of the open area, which is not. The etch rates of silicon and tungsten in the pe mode as a function of oxygen content are shown in fig. Chemical dry etching of silicon nitride and silicon. Wet and dry etching atmosphere, bath vacuum chamber environment and equipment anisotropic isotropic except for etching crystalline materials directionality 1 high cost, hard to implement 2 low throughput 3 poor selectivity 4 potential radiation damage 1 inadequate for defining feature size dry etching is difficult for ni since there are no volatile compounds you can pump away from the etching chamber. One of the key factors contributing to this market growth. 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. The excited ions in the plasma collide with the material and remove it without any chemicals. Patterning pdms using a combination of wet and dry etching.
The dry etching technology can split in three separate classes called reactive ion etching rie, sputter etching, and vapor phase etching. Oehrleinb department of physics, the university of albany, state university of new york, 1400 washington avenue. The author describes the device manufacturing flow, and explains in which part of the flow dry etching is actually used. Several methods have been used for dry etching, including. The possibility of dry etching of aluminium by chlorine containing gases is one of the big advantages over other materials such as. Etching is a critically important process module, and every wafer undergoes many etching steps before it is complete. In rie, the substrate is placed inside a reactor in which several gases are introduced. This is the most enviromentally friendly method available.
Dry etching of inpbased materials using a highdensity icp plasma system viewport for optical emission spectroscopy or laser interferometry gas inlet with axially symmetric distribution electrostatic shield quartz or alumina tube watercooled rf coil antenna wafer clamping mechanism sputter shield 200mm. This isotropic etch process shows high etch selectivity of silicon against pdms, parylene, su8, silicon dioxide sio 2 and silicon nitride sin x. Introduction aluminium remains the main interconnect material in integrated circuit fabrication, despite increasing interest in alternative materials. Chapter 2 dry etching characteristics of sin x and sio x icp has been extensively applied to ic manufacturing. The method of dry etching crosslinked su8 has been discussed by many researchers 11 14. There is one exception and that is nickel carbonyl, nico4 you have to etch with. Garra department of physics, georgetown university, washington, d. The etch process is completely dry, and it eliminates the stiction problems that occur during wet etch process. Dry etching, or plasma etching, is an etching process that utilizes free radicals produced by plasma.
Wet etching vs dry etching memsstar etch and deposition. Reactive ion etching systems rie plasma etching samco inc. The analysts forecast the global semiconductor dry etching equipment market to grow at a cagr of 2. Chapter 2 dry etching characteristics of sinx and siox. Reduction of device damage during dry etching of advanced. Eh 2 and o 2 in dry etching ealuminum dry etch esio2 dry etch edeep oxide etch 1122005 eel6935 advanced mems spring 2005 instructor. Source power 350 w and the cl 2 gas flow 100 sccm were kept constant. Patterning pdms using a combination of wet and dry etching article pdf available in journal of micromechanics and microengineering 353219.
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