Reflectance of the samples was found to be consistently below 10%, the lowest being 3%. Optical emission spectroscopy of plasma etching of gaas. Because of the unique physical properties, various gaas micro and nanostructures have attracted increasing research attention for many technical applications such as solar cells, lightemitting diodes, and fieldeffect transistors. As a comparison, the line width measured with sem is presented in fig.
Scanning electron microscope sem observations showed that the presence of nitrogen generated the deposition of a passivation layer, which had a. This structure, fully compatible with gaas heterostructure field effect transistor hfet technology, was developed to be used for design of micromechanical thermal converter mtc device. Capacitively coupled plasma ccp etching, so called reactive ion etching rie, is one of popular patterning techniques for semiconductor processing. Reactive ion etching of gaas with cci f etch rates. Addition of nitrogen into bcl3sf6 plasma improved sidewall passivation of gaas during etching. Mcdowell road, phoenix, az 85008 usa 3flipchip international, 3701 e. High selectivity inductively coupled plasma etching of gaas over ingap. Ar rfplasma and microwave electron cyclotron resonance ecr plasma etching of gaas and inp is presented. The predominant dry etching technique used for gaas has been reactive ion etching rie, in which the sample is placed on the small powered electrode in an. In addition, the selectivity of aigaas over gaas as much as 600. This paper describes optical emission spectroscopy between 260 800 nm for cich 3 h 2 rfplasma reactive ion etching of al 0. Advanced selective dry etching of gaasalgaas in high density inductively coupled plasmas j. Inductively coupled plasma etching of gaas in cl2ar, cl2ar.
These damages are formed by gaas broken bonds and dislocations due to etching and ion bombardment, which. The selectivity determined by scanning electron microscopy of the oxide etch over the substrate. To etch algaas and alasgaas dbr structures with a vertical sidewall profile using panasonic icp etcher and cl 2 n 2 based chemistry. The recipe was optimized by varying various etch parameters. Under the plasma condition used here and allowing for. However, the absolute etch rates are lower 70 nm min. Pdf inductively coupled plasma etching in icl and ibrbased. The plasma etching is performed using a reactive ion etch rie reactor combined with an external helical rf coil. Characterization of etched gaas surfaces 675 500 750 1250 0. Clawsonmaterials science and engineering 31 2001 1438 3. 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. To etch gaas using unaxis icp etcher at a lowtemperature with a laser interferometer monitoring the etch depth. Gasb and algaas showed maxima in their etch rates for both plasma chemistries as a function of interhalogen percentage, while gaas showed increased etch rates with plasma composition in both chemistries. Polyimidefixed gaas island structure prepared using.
Ccp has advantages for plasma etching of gaas in terms of low cost of ownership and easy maintenance. Inductively coupled plasma etching of gaasalgaas was investigated in bcl3cl2ar using a mixture design experiment. Etch rate of gaas was raised to 3,700 amin in bcl3sf6he plasmas with 10 sccm he flow, while that of algaas was very hard to measure etching. According to the model extracted from the experiment, the etch rate was linearly proportional to the gas. When etching of a few micron thick gaas feature is an issue, attention is paid to new types of plasma source for relatively fast etch rate. Pdf we report on the etching characteristics of gaas and algaas in capacitive bcl3sf6 plasmas modulated at a pulse timing of a few milliseconds find. In this regard, numerous fabrication techniques have been explored, and among all, metalassisted chemical etching is successfully applied to gaas in order to. A 42% h 2 58% ccl 2 f 2 plasma etched gaas only 12 times faster than it etched oxide. Advanced and reliable gaasalgaas icpdrie etching for. Reactive ion etching typically lower pressures, ion bombardment substrate placed on. Cr also gets etched in our plasma etching recipe, though it is a slow process at a rate of. It involves a highspeed stream of glow discharge of an appropriate gas mixture being shot in pulses at a sample.
Pdf extremely high aspect ratio gaas and gaasalgaas. On the other hand the use of oxygen 0v bias plasmas can be used for isotropic surface termination of ch terminated diamond surface. Plasma plasma is a partially ionized gas composed of equal numbers of positive and negative charges, as well as some neutral molecules. Dry etching is a complex process with many factors that must be considered for optimization of the process. Among several fabrication methods, the topdown approach using plasma etching technology offers uniform and precisely controlled structures. High density plasma etching of gaas, gasb and aigaas was performed in ic1ar and lbrar chemistries using an inductively coupled plasma icp source. It was also noticed that addition of he increased the etch rate of. For many etch steps, part of the wafer is protected from the etchant by a masking material which resists etching. Pearton university of florida gainsville, fl we report a breakthrough for selective etching of gaas over al xga 1. Dry etching, also called plasma etching, sputters or dissolves the materials using reactive ions in a gas phase. The step height was then measured with a mechanical stylus, and the etch rate was found by dividing the step height by the exposure time.
Although dry etching ap proaches have been reported in the literature using a broad variety of plasma etch tools, there is still need to meet the. Inductively coupled plasma reactive ion etching icprie of gallium arsenide gaas using bcl 3 cl 2 ar plasma was carried out for photonic crystal phc applications. To fabricate the island structure frontside surface micromachining is. Pdf reduction of dry etch damage to gaas using pulsetime. Etching is a critically important process module, and every wafer undergoes many etching steps before it is complete. Dry etching process of gaas in capacitively coupled bcl3. We report the development and characterizations of gaas via hole processes using bcl 3 ar and cl 2 ar plasmas generated by an electron cyclotron resonance ecr system. Bulk gaas and 3000 a thick algaas epilayers with 20 % al composition were prepared on gaas wafers. Inductively coupled plasma etching of the gaas nanowire. Bcl3 cl2 process in an inductively coupled plasma icp.
The flow rates and ratios of the etching gases were studied. This unit of pressure, commonly used in vacuum engineering, equals approximately 3. It is found that the rate of etching increases with gas pressure in the range 10300. Mechanisms of silicon etching in fluorine and chlorine. Gaas micromachining technologies were used for fabricating polyimidefixed thermally insulated gaas island structure. Highdensity plasma etching of compound semiconductors. Dry plasma etching of gaas vias using bcl3ar and cl2ar plasmas. Plasma etching is a form of plasma processing used to fabricate integrated circuits. Conclusion figure 3 gaas plasma scribing etch depth and 1 samco now technical report, vol. Inductively coupled plasma etching of gaas algaas was investigated in bcl3cl2ar using a mixture design experiment. It is also shown that the hydrogen plasma etched and air exposed gaas surfaces have a gaas concentration ratio nearly equal to that of the air cleaved gaas surface.
The gaasalgaas plasma etching was a singlestep process using a cl2bcl3 ar gas mixture with various fractions of n2. Advanced selective dry etching of gaas algaas in high density inductively coupled plasmas j. Plasmaetching of algaas dbr structure using panasonic icp etcher with cl 2, n 2 based chemistry purpose. Temperature dependence of reactive ion etching of gaas. Hydrogen plasma etching of semiconductors and their oxides. During the process, the plasma generates volatile etch products at room temperature from the chemical. For more information about gaas wafer plasma scribing with icp etching, please contact one of our representatives. Etching gas is introduced into the chamber continuously plasma is created by rf power reactive species radicals and ions are generated in the plasma radicals. Inductively coupled plasma etching of gaas in cl2ar, cl2. Plasmaetching of algaas dbr structure using panasonic icp. Highdensity plasma etching of gaas, gasb, and algaas was performed iniclar and ibrar chemistries using an inductively coupled plasma icpsource. In addition, the reaction byproducts should be highly volatile. Modern vlsi processes avoid wet etching, and use plasma etching instead. Reference gaa s rem ainin g fla t su r fa c e w id t h.
Request pdf on aug 1, 2015, kai liu and others published inductively coupled plasma etching of gaas in cl2ar, cl2aro2 chemistries with photoresist mask find, read and cite all the research. Etch rates and surface chemistry of gaas and aigaas. Inductively coupled plasma etching in icl and ibrbased. Gasb and algaas showed maxima in their etch rates for both plamachemistries as a function of. The reactive ion etching of au on gaas substrates in a high. Designed experiments have shown that pillar formation during the plasma etch process can be reduced through the use of higher cl. Guide to references on iiiv semiconductor chemical etching. The average gaas etch rate was found to increase with increasing. Therefore, there was a synergetic effect of n 2 in the bcl 3 n 2 plasma.
Introduction the dry etching of gaas and related compounds is gaining a resurgence of interest, largely due to the need to achieve highresolution, anisotropic etching in device applications. Reactive ion etching of gaas with cci f etch rates, surface. Etches were characterized in terms of rate and anisotropy using scanning electron microscopy, and rootmeansquare surface roughness using atomic force microscopy. Nanoimprint lithography1,2 and plasma etching technology is widely used for semiconductor device fabrication. The plasma produces energetic free radicals, neutrally charged, that react at the. We would be happy to discuss your specific process needs. The etching of the nanowires was done in an oxford plasmatherm icprie system using cl. The optical emission species identified for gaas and inp etching are. Etch rates from 200 to over 3000 nmmin were obtained. Plasma etching of gaas and algaas using 300 khz and. Optical emission spectroscopy of plasma etching of gaas and.
The plasma source, known as etch species, can be either charged or neutral atoms and radicals. The etching of au using photoresist masks and hard masks on gaas substrates was investigated using a dual frequency high density plasma etch reactor. The etcher has he backside cooling configuration and a mechanical ceramic clamp on the wafer. Reactive ion etching is an anisotropic processreactive ion etching is an anisotropic process. Experimental a plasmatherm slr 770 inductively coupled plasma etcher was utilized for selective etching of gaas over al0. Mechanistic characteristics of metalassisted chemical. Wet chemical digital etching of gaas at room temperature. Icp plasma dramatically increased the etch rate of gaas and resultant selectivity of gaas over algaas without affecting the plasma stability. For photonic device applications, dry or plasma etching is used fin device isolation, fineline pattern transfer, and fabrication of optical quality interfaces.
Pdf high selectivity inductively coupled plasma etching. Highdensity inductively coupled plasma etching of gaas. The effect of the in and outdiffuse of the reactive species and etch byproducts, of the bcl 3 ar plasma, on the etch rate of the gaas vias has been studied. A new room temperature wet chemical digital etching technique for gaas is presented which uses hydrogenperox ide and an acid in a twostep etching process to remove gaas in approximately 15 a increments, in the first step, gaas. Finally, highlyordered gaas nanowire arrays with high quality surface morphology were obtained with the volumetric flow rates at 9 sccm and 21 sccm for bcl 3 and n 2 gases, respectively.
Gaas pillars with high aspect ratio were fabricated using chlorine chemistry. The etching of the nanowires was done in an oxford plasmatherm icprie system using cl 2n 2 chemistry. Pdf defect penetration during the plasma etching of. Eliminating pillars during gaas via etch formation plasmatherm. The etching of silicon by free fluorine atoms is a good example of an isotropic chemical mechanism. It utilizes plasma instead of liquid etchants to remove the materials, which is more precise, controllable and repeatable compared to wet etching, but a more expensive vacuum system is required. Bias power, etch time, flow rate, gaas, inductively coupled plasma, photoresist mask, plasma etching, surface morphology. Since samples typically heat up during rie treatments, and temperature has probably been the most neglected variable in plasma etching, it is of interest to look at the temperature dependence of ccl 2 f. Plasma etchers can operate in several modes by adjusting the parameters of the plasma. Dry etching substrates are immersed in a reactive gas plasma. Highly ordered vertical gaas nanowire arrays with dry. Petersburg, fl 33716 usa 2on semiconductor, 5005 e. Highly ordered vertical gaas nanowire arrays with dry etching. Chlorinebased inductively coupled plasma etching of gaas wafer.
Inductively coupled plasma icp etching of gaas, gap, and inp is reported as a function of plasma chemistry, chamber pressure, rf power, and source power. Pillar formation during gaas via etching can arise from a number of causes including residues from upstream operations grinding, mounting, photolithography, etc. 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. Gaas through wafer vias was studied primarily using a. Dry plasma etching of gaas vias using bcl3ar and cl2ar. 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. Pdf a study on etching parameters of a reactive ion beam. Inductively coupled plasma icp etching with bcl3sf6n2he chemistries showed extremely high selectivity 200.
The effect of etching conditions on inp morphology is also examined. Iiiv dry etching cns, harvard university prepared by l. Lowtemperature plasma etching of gaas, algaas, and alas. Etching is used in microfabrication to chemically remove layers from the surface of a wafer during manufacturing. Pdf inductively coupled plasma etching in icl and ibr. Dry etching of compound semiconductors is becoming increasingly important as design ruler shrink for electronic devices. Gaas plasma etching recipe needs to be developed to meet each customers process demands on shape and geometry of gaas pillar arrays.