Dry Etching of MRAM Structures

2000 ◽  
Vol 614 ◽  
Author(s):  
S.J. Pearton ◽  
H. Cho ◽  
K.B. Jung ◽  
J.R. Childress ◽  
F. Sharifi ◽  
...  
Keyword(s):  
Plasma Etching ◽  
Significant Influence ◽  
Ex Situ ◽  
Metallic Multilayers ◽  
Ion Energy ◽  
Magnetic Performance ◽  
Ion Energies ◽  
Density Plasma ◽  
Cleaning Protocol

ABSTRACTA wide variety of GMR and CMR materials have been patterned by high density plasma etching in both corrosive (Cl2-based) and non-corrosive (CO/NH3) plasma chemistries. The former produce much higher etch rates but require careful in-situ or ex-situ, post-etch cleaning to prevent corrosion of the metallic multilayers. The former may have application for shallow etching of NiFe-based structures, but there is little chemical contribution to the etch mechanism and mask erosion can be a problem. The magnetic performance of patterned MRAM elements is stable over long periods (>1 year) after etching in Cl2 plasmas, provided a suitable cleaning protocol is followed. It is also clear that high ion energies during patterning of magnetic materials can have a significant influence on their coercivity. The effects of ion energy, ion flux and process temperature are discussed.

scholarly journals Etch Processing of III-V Nitrides

1999 ◽  
Vol 4 (S1) ◽  
pp. 902-913 ◽  
Author(s):  
Charles R. Eddy
Keyword(s):  
Plasma Etching ◽  
Microwave Power ◽  
Ohmic Contacts ◽  
High Density ◽  
Etching Process ◽  
Ion Energy ◽  
Plasma Etching Process ◽  
Device Processing ◽  
The Impact ◽  
Density Plasma

As III-V nitride devices advance in technological importance, a fundamental understanding of device processing techniques becomes essential. Recent works have exposed various aspects of etch processes. The most recent advances and the greatest remaining challenges in the etching of GaN, AlN, and InN are reviewed. A more detailed presentation is given with respect to GaN high density plasma etching. In particular, the results of parametric and fundamental studies of GaN etching in a high density plasma are described. The effect of ion energy and mass on surface electronic properties is reported. Experimental results identify preferential sputtering as the leading cause of observed surface non-stoichiometry. This mechanism provides excellent surfaces for ohmic contacts to n-type GaN, but presents a major obstacle for Schottky contacts or ohmic contacts to p-type GaN. Chlorine-based discharges minimize this stoichiometry problem by improving the rate of gallium removal from the surface. In an effort to better understand the high density plasma etching process for GaN, in-situ mass spectrometry is employed to study the chlorine-based high density plasma etching process. Gallium chloride mass peaks were monitored in a highly surface sensitive geometry as a function of microwave power (ion flux), total pressure (neutral flux), and ion energy. Microwave power and pressure dependencies clearly demonstrate the importance of reactive ions in the etching of wide band gap materials. The ion energy dependence demonstrates the importance of adequate ion energy to promote a reasonable etch rate (≥100-150 eV). The benefits of ion-assisted chemical etching are diminished for ion energies in excess of 350 V, placing an upper limit to the useful ion energy range for etching GaN. The impact of these results on device processing will be discussed and future needs identified.

Dry Etch Damage in GaAs P-N Junctions

1991 ◽  
Vol 240 ◽  
Author(s):  
S. J. Pearton ◽  
F. Ren ◽  
C. R. Abernathy ◽  
T. R. Fullowan ◽  
J. R. Lothian
Keyword(s):  
Plasma Etching ◽  
Ion Bombardment ◽  
Plasma Exposure ◽  
Base Resistance ◽  
Ion Energy ◽  
Ion Energies ◽  
A Minor ◽  
P Type ◽  
Dry Etch ◽  
Very High

ABSTRACTGaAs p-n junction mesa-diode structures were fabricated so that both n- and p-type layers could be simultaneously exposed to either O2 or H2 discharges. This simulates the ion bombardment during plasma etching with either CCl2F2/O2 or CH4/H2 mixtures. The samples were exposed to 1 mTorr discharges for period of 1–20 min with DC biases of -25 to -400V on the cathode. For O2 ion bombardment, the collector resistance showed only minor (≤10%) increases for biases up to -200 V and more rapid increases thereafter. In our structure, this indicates that bombardment-induced point defects penetrate at least 500 Å of GaAs for ion energies of ≥200eV. The base resistance displayed only a minor increase (∼10%) over the pre-exposure value even for O+ ion energies of 375 eV, due to the very high doping (1020 cm−3 ) in the base. More significant increases in both collector and base resistances were observed for hydrogen ion bombardment due to hydrogen passivation effects. We will give details of this behaviour as a function of ion energy, plasma exposure time and post-treatment annealing temperature.

scholarly journals Ion-Irradiation-Induced Amorphization Of Cadmium Niobate Pyrochlore

2000 ◽  
Vol 650 ◽  
Author(s):  
A. Meldrum ◽  
K. Beaty ◽  
L. A. Boatner ◽  
C. W. White
Keyword(s):  
Electron Microscope ◽  
Ambient Temperature ◽  
Transmission Electron Microscope ◽  
Room Temperature ◽  
Ion Irradiation ◽  
Ex Situ ◽  
Temperature Dependent ◽  
Transmission Electron ◽  
Ion Energies

ABSTRACTIrradiation-induced amorphization of Cd2Nb2O7 pyrochlore was investigated by means of in-situ temperature-dependent ion-irradiation experiments in a transmission electron microscope, combined with ex-situ ion-implantation (at ambient temperature) and RBS/channeling analysis. The in-situ experiments were performed using Ne or Xe ions with energies of 280 and 1200 keV, respectively. For the bulk implantation experiments, the incident ion energies were 70 keV (Ne+) and 320 keV (Xe2+). The critical amorphization temperature for Cd2Nb2O7 is ∼480 K (280 keV Ne+) or ∼620 K (1200 keV Xe2+). The dose for in-situ amorphization at room temperature is 0.22 dpa for Xe2+, but is 0.65 dpa for Ne+ irradiation. Both types of experiments suggest a cascade overlap mechanism of amorphization. The results were analyzed in light of available models for the crystalline-to-amorphous transformation and were compared to previous ionirradiation experiments on other pyrochlore compositions.

Electron Cyclotron Resonance Plasma Processing of GaAs-AlGaAs Hemt Structures

1991 ◽  
Vol 240 ◽  
Author(s):  
S. J. Pearton ◽  
F. Ren ◽  
J. R. Lothian ◽  
T. R. Fullowan ◽  
R. F. Kopf ◽  
...  
Keyword(s):  
Plasma Etching ◽  
Cyclotron Resonance ◽  
Electron Cyclotron Resonance ◽  
Complete Removal ◽  
Pattern Transfer ◽  
Hydrogen Passivation ◽  
Ion Energy ◽  
Ion Energies ◽  
Resonance Plasma ◽  
Or Gate

ABSTRACTThe damage introduced into GaAs/AlGaAs HEMT structures during pattern transfer (O2 plasma etching of the PMGI layer in a trilevel resist mask) or gate mesa etching (CCl2F2/O2 or CH4/H2/Ar etching of GaAs selectively to AlGaAs) has been studied. For etching of the PMGI, the threshold O+ ion energy for damage introduction into the AlGaAs donor layer is ∼200 eV. This energy is a function of the PMGI over-etch time. The use of ECR-RF O2 discharges enhances the PMGI etch rate without creating additional damage to the device. Gate mesa etching produces measurable damage in the underlying AlGaAs at DC negative biases of 125–150V. Substantial hydrogen passivation of the Si dopants in the AlGaAs occurs with the CH4 /H2 /Ar mixture. Recovery of the initial carrier concentration in the damaged HEMT occurs at ∼400°C, provided the maximum ion energies were dept to ≤400 eV. Complete removal of residual AIF3 on the CCl2F2/O2 exposed AlGaAs was obtained after H2O and NH4 OH:H2O rinsing while chlorides were removed by H2O alone.

Characterization of the CH4/H2/Ar High Density Plasma Etch Process for HgCdTe

1996 ◽  
Vol 450 ◽  
Author(s):  
C. R. Eddy ◽  
D. Leonhardt ◽  
V. A. Shamamian ◽  
R. T. Holm ◽  
O. J. Glembocki ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Plasma Etching ◽  
High Density ◽  
Scanning Electron Micrographs ◽  
Plasma Etch ◽  
Ion Energy ◽  
Residual Damage ◽  
Hall Effect Measurements ◽  
Density Plasma

ABSTRACTHigh density plasma etching of Hg1−xCdxTe in CH4/H2/Ar chemistry is examined using mass spectroscopy with careful surface temperature monitoring. The dominant etch products are monitored as a function of surface temperature (15–200°C), ion energy (20–200 eV), total pressure (0.5–5 mTorr), microwave power (200–400 W), and flow fraction of methane in the etch gas mixture (0–30%). In addition, observations are made regarding the regions of parameter space which are best suited to anisotropie, low damage etch processing. These observations are compared with previous results in the form of scanning electron micrographs of etched features for anisotropy evaluation and Hall effect measurements for residual damage. Insights to the overall etch mechanism are given.

Role of Ions in Bias Enhanced Nucleation of Diamond

1995 ◽  
Vol 388 ◽  
Author(s):  
J.M. Lannon ◽  
J.S. Gold ◽  
Cd. Stinespring
Keyword(s):  
Thin Films ◽  
Silicon Carbide ◽  
Surface Composition ◽  
Hydrogen Ions ◽  
Ion Energy ◽  
Transfer Processes ◽  
Ion Interactions ◽  
Ion Energies

AbstractIon-surface interactions are thought to play a role in bias enhanced nucleation of diamond. To explore this hypothesis and understand the mechanisms, surface studies of hydrogen and hydrocarbon ion interactions with silicon and silicon carbide have been performed. the experiments were carried out at room temperature and used in-situ auger analyses to monitor the surface composition of thin films produced or modified by the ions. Ion energies ranged from 10 to 2000 eV. Hydrogen ions were found to modify silicon carbide thin films by removing silicon and converting the resulting carbon-rich layers to a mixture of sp2- and sp3-C. the interaction of hydrocarbon ions with silicon was shown to produce a thin film containing SiC-, sp2-, and sp3-C species. IN general, the relative amount of each species formed was dependent upon ion energy, fluence, and mass. the results of these studies, interpreted in terms of chemical and energy transfer processes, provide key insights into the mechanisms of bias enhanced nucleation.

Room Temperature Nitridation and Oxidation of Si, Ge and Mbegrown Sige Using Low Energy Ion Beams (0.1-1 Kev).

1991 ◽  
Vol 223 ◽  
Author(s):  
O. Vancauwenberghe ◽  
O. C. Hellman ◽  
N. Herbots ◽  
J. L. Olson ◽  
W. J. Tan ◽  
...  
Keyword(s):  
Room Temperature ◽  
Ion Beam ◽  
Film Properties ◽  
Dielectric Thin Films ◽  
Ion Energy ◽  
Insulating Films ◽  
Ion Energies ◽  
Energy Dependent

ABSTRACTDirect Ion Beam Nitridation (IBN) and Oxidation (IBO) of Si, Ge, and Si0.8Ge0.2 were investigated at room temperature as a function of ion energy. The ion energies were selected between 100 eV and 1 keV to establish the role of energy on phase formation and film properties. Si0.8Ge0.2 films were grown by MBE on Si (100) and transferred in UHV to the ion beam processing chamber. The modification of composition and chemical binding was measured as a function of ion beam exposure by in situ XPS analysis. The samples were nitridized or oxidized using until the N or O 1s signal reached saturation for ion doses between 5×1016 to 1×1017 ions/cm2. Combined characterization by XPS, SEM, ellipsometry and cross-section TEM showed that insulating films of stoichiometric SiO2 and Si-rich Si3N4 were formed during IBO and IBN of Si at all energies used. The formation of Ge dielectric thin films by IBO and IBN was found to be strongly energy dependent and insulating layers could be grown only at the lower energies (E ≤ 200 eV). In contrast to pure Ge, insulating SiGe-oxide and SiGe-nitride were successfully formed on Si0.8Ge0.20.2 at all energies studied.

Etch Processing of III-V Nitrides

1998 ◽  
Vol 537 ◽  
Author(s):  
Charles R. Eddy
Keyword(s):  
Plasma Etching ◽  
Microwave Power ◽  
Ohmic Contacts ◽  
High Density ◽  
Etching Process ◽  
Ion Energy ◽  
Plasma Etching Process ◽  
Device Processing ◽  
The Impact ◽  
Density Plasma

AbstractAs III-V nitride devices advance in technological importance, a fundamental understanding of device processing techniques becomes essential. Recent works have exposed various aspects of etch processes. The most recent advances and the greatest remaining challenges in the etching of GaN, AIN, and InN are reviewed. A more detailed presentation is given with respect to GaN high density plasma etching. In particular, the results of parametric and fundamental studies of GaN etching in a high density plasma are described. The effect of ion energy and mass on surface electronic properties is reported. Experimental results identify preferential sputtering as the leading cause of observed surface non-stoichiometry. This mechanism provides excellent surfaces for ohmic contacts to n-type GaN, but presents a major obstacle for Schottky contacts or ohmic contacts to p-type GaN. Chlorine-based discharges minimize this stoichiometry problem by improving the rate of gallium removal from the surface. In an effort to better understand the high density plasma etching process for GaN, in-situ mass spectrometry is employed to study the chlorine-based high density plasma etching process. Gallium chloride mass peaks were monitored in a highly surface sensitive geometry as a function of microwave power (ion flux), total pressure (neutral flux), and ion energy. Microwave power and pressure dependencies clearly demonstrate the importance of reactive ions in the etching of wide band gap materials. The ion energy dependence demonstrates the importance of adequate ion energy to promote a reasonable etch rate (≥ 100-150 eV). The benefits of ion-assisted chemical etching are diminished for ion energies in excess of 350 V, placing an upper limit to the useful ion energy range for etching GaN. The impact of these results on device processing will be discussed and future needs identified.

Characterization of GaAs Surfaces Subjected to A Cl2/Ar High Density Plasma Etching Process

1996 ◽  
Vol 448 ◽  
Author(s):  
C.R. Eddy ◽  
O.J. Glembocki ◽  
V.A. Shamamian ◽  
D. Leonhardt ◽  
R.T. Holm ◽  
...  
Keyword(s):  
Plasma Etching ◽  
Optical Measurement ◽  
Diffuse Reflectance Spectroscopy ◽  
Surface Damage ◽  
High Density ◽  
Ex Situ ◽  
Process Conditions ◽  
Spectroscopic Techniques ◽  
Density Plasma

AbstractHigh density plasma etching of III-V compound semiconductors is critically important to the development of advanced optoelectronic and high frequency devices. Unfortunately, the surface chemistry of these processes is not well understood. In an effort to monitor surface processes and their dependence on process conditions in a realistic etching environment, we have applied mass spectroscopic techniques for the study of GaAs etching in Cl2/Ar chemistry. Etch product chlorides were monitored, together with optical measurement of the surface temperature by diffuse reflectance spectroscopy, as pressure (neutral flux), microwave power (ion flux) and rf bias of the substrate (ion energy) were varied. Observations from the spectroscopic techniques were correlated with ex situ surface damage assessments of unpassivated surfaces by photoreflectance spectroscopy. As a result, insights are made into regions of process conditions that are well suited to anisotropic, low damage etching.

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