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.

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.

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.

Dry and Wet Etch Processes for NiMnSb, LaCaMnO3 and Related Materials

1997 ◽  
Vol 494 ◽  
Author(s):  
J. Hong ◽  
J. J. Wang ◽  
E. S. Lambers ◽  
J. A. Caballero ◽  
J. R. Childress ◽  
...  
Keyword(s):  
Plasma Etching ◽  
Smooth Surface ◽  
Dielectric Materials ◽  
Ion Density ◽  
Ion Energy ◽  
Sensor Devices ◽  
Etch Rates ◽  
Surface Morphologies ◽  
Wet Etch ◽  
Dry Etch

ABSTRACTA variety of plasma etching chemistries were examined for patterning NiMnSb Heusler thin films and associated A12O3 barrier layers. Chemistries based on SF6 and Cl2 were all found to provide faster etch rates than pure Ar sputtering. In all cases the etch rates were strongly dependent on both the ion flux and ion energy. Selectivities of ≥20 for NiMnSb over A12O3 were obtained in SF6-based discharges, while selectivities ≤5 were typical in Cl2 and CH4/H2 plasma chemistries. Wet etch solutions of HF/H2O and HNO3/H2SO4/H2O were found to provide reaction-limited etching of NiMnSb that was either non-selective or selective, respectively, to A12O3. In addition we have developed dry etch processes based on Cl2/Ar at high ion densities for patterning of LaCaMnO3 (and SmCo permanent magnet biasing films) for magnetic sensor devices. Highly anisotropie features are produced in both materials, with smooth surface morphologies. In all cases, SiO2 or other dielectric materials must be used for masking since photoresist does not retain its geometrical integrity upon exposure to the high ion density plasma.

Properties and microstructure of tungsten films deposited by ion-assisted evaporation

1991 ◽  
Vol 6 (1) ◽  
pp. 80-91 ◽  
Author(s):  
R.A. Roy ◽  
R. Petkie ◽  
A. Boulding
Keyword(s):  
Compressive Stress ◽  
Impurity Content ◽  
Ion Bombardment ◽  
Film Properties ◽  
Ion Energy ◽  
Monotonic Trend ◽  
Ion Energies ◽  
Argon Ion Bombardment ◽  
Substrate Temperatures ◽  
Argon Ion

The modification of film properties in evaporated tungsten was studied as a function of deposition environment. Using concurrent argon ion bombardment of the growing film, the stress varied in the same manner at all ion energies and substrate temperatures. Initial increases in tensile stress are followed by a monotonic trend toward compressive stress, for all sets of films. On the other hand, the qualitative changes in film resistivity with concurrent bombardment were dependent on the ion energy and substrate temperature, showing increases at high temperature and energy and decreases at low temperature and energy. Changes in the microstructure and impurity content in deposited films were found to be strongly linked to stress and resistivity changes. The trend toward compressive stress induced by high levels of ion bombardment is primarily reflected in an increase in (110) orientation. Increased resistivity is related to decreased grain size, increased (110) texture, and increased levels of film argon and oxygen content. By choice of deposition conditions, both the resistivity and stress can be minimized.

Damage Introduction in Ingap and Aigaas by Electron Cyclotron Resonance ar Plasmas

1996 ◽  
Vol 421 ◽  
Author(s):  
J. W. Lee ◽  
S. J. Pearton ◽  
R. R. Stradtmann ◽  
C. R. Abernathy ◽  
W. S. Hobson ◽  
...  
Keyword(s):  
Cyclotron Resonance ◽  
Electron Cyclotron Resonance ◽  
Ion Bombardment ◽  
Electron Cyclotron ◽  
Type Material ◽  
Plasma Damage ◽  
Ion Density ◽  
Ion Energy ◽  
Electron Traps ◽  
P Type

AbstractChanges in sheet resistance of n- and p-type InGaP exposed to Electron Cyclotron Resonance Ar plasmas have been used to measure the introduction of ion-induced damage. P-type material is much more resistant to change in its conductivity than n-type InGaP, indicating that electron traps are the predominant entity produced by the ion bombardment. For short (˜1 min.) plasma exposures the ion current is more important than ion energy in producing resistance changes. Annealing of damage in both conductivity types occurs with an activation energy of ˜3.4±0.5eV. p+A1GaAs is found to be much more susceptible than n+AlGaAs to the introduction of electrically active deep levels during exposure to Electron Cyclotron Resonance Ar plasmas. In both AlGaAs materials the resistivity of thin (˜0.5μm) epitaxial layers increases rapidly with both plasma exposure time and the ion energy, while the ion density in the Ar discharge has a much greater influence on p+AlGaAs than n-type material. These results suggest that the energetic ion bombardment introduces deep hole traps more readily than deep electron traps in AlGaAs and that pnp transistor structures will be more susceptible to plasma damage than comparable npn structures.

Development of Backside Scanning Capacitance Microscopy Technique for Advanced SOI Microprocessors

2006 ◽  
Author(s):  
Vinod Narang ◽  
P. Muthu ◽  
J.M. Chin ◽  
Vanissa Lim
Keyword(s):  
Plasma Etching ◽  
Data Interpretation ◽  
Parameters Optimization ◽  
Scanning Capacitance Microscopy ◽  
Microscopy Technique ◽  
Thermal Oxide ◽  
Specific Analysis ◽  
Thin Oxide ◽  
P Type ◽  
Uv Ozone

Abstract Implant related issues are hard to detect with conventional techniques for advanced devices manufactured with deep sub-micron technology. This has led to introduction of site-specific analysis techniques. This paper presents the scanning capacitance microscopy (SCM) technique developed from backside of SOI devices for packaged products. The challenge from backside method includes sample preparation methodology to obtain a thin oxide layer of high quality, SCM parameters optimization and data interpretation. Optimization of plasma etching of buried oxide followed by a new method of growing thin oxide using UV/ozone is also presented. This oxidation method overcomes the limitations imposed due to packaged unit not being able to heat to high temperature for growing thermal oxide. Backside SCM successfully profiled both the n and p type dopants in both cache and core transistors.

Analysis of Plasma Properties and Deposition of Amorphous Silicon Alloy Solar Cells Using Very High Frequency Glow Discharge

1999 ◽  
Vol 557 ◽  
Author(s):  
B. Yan ◽  
J. Yang ◽  
S. Guha ◽  
A. Gallagher
Keyword(s):  
Solar Cells ◽  
High Frequency ◽  
Lower Energy ◽  
Ionic Current ◽  
Ion Bombardment ◽  
Half Width ◽  
Rf Plasma ◽  
Very High Frequency ◽  
Very High ◽  
Ionic Energy

AbstractPositive ionic energy distributions in modified very-high-frequency (MVHF) and radio frequency (RF) glow discharges were measured using a retarding field analyzer. The ionic energy distribution for H2 plasma with 75 MHz excitation at a pressure of 0.1 torr has a peak at 22 eV with a half-width of about 6 eV. However, with 13.56 MHz excitation, the peak appears at 37 eV with a much broader half-width of 18 eV. The introduction of SiH4 to the plasma shifts the distribution to lower energy. Increasing the pressure not only shifts the distribution to lower energy but also broadens the distribution. In addition, the ionic current intensity to the substrate is about five times higher for MVHF plasma than for RF plasma. In order to study the effect of ion bombardment, the deposition of a-Si alloy solar cells using MVHF was investigated in detail at different pressures and external biases. Lowering the pressure and negatively biasing the substrate increases ion bombardment energy and results in a deterioration of cell performance. It indicates that ion bombardment is not beneficial for making solar cells using MVHF. By optimizing the deposition conditions, a 10.8% initial efficiency of a-Si/a-SiGe/SiGe triple-junction solar cell was achieved at a deposition rate of 0.6 nm/sec.

scholarly journals Idiotypic analysis of potential and available repertoires in the arsonate system.

1984 ◽  
Vol 160 (1) ◽  
pp. 1-11 ◽  
Author(s):  
M Slaoui ◽  
O Leo ◽  
J Marvel ◽  
M Moser ◽  
J Hiernaux ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
B Cells ◽  
Keyhole Limpet Hemocyanin ◽  
High Frequencies ◽  
Specific Subset ◽  
A Minor ◽  
Very High Frequencies ◽  
Very High ◽  
Limiting Dilution

We have shown that, by suitable idiotypic manipulation, BALB/c mice can express the major cross-reactive idiotype (CRI) of A/J mice in response to azophenylarsonate (Ars). In order to know if the CRIA idiotype is present in the potential repertoire of BALB/c before any intentional selection, we used polyclonal activation in vitro and limiting dilution analysis. The readout was done with two monoclonal anti-CRIA antibodies that recognize distinct idiotopes on a CRIA+ A/J germline-encoded monoclonal antibody. We studied the frequency of CRIA+ lipopolysaccharide (LPS)-reactive cells in the spleens of nonimmune and immune A/J mice and in the spleens of naive and manipulated (i.e., producing CRIA+ antibodies) BALB/c mice. A/J and BALB/c naive individuals presented very high frequencies of Ars-specific B cells while the frequency of CRIA+ B cells was only a minor subset (0.5%) of the total Ars-specific subset in the two strains. When A/J mice were immunized with Ars-keyhole limpet hemocyanin, a clear preferential expansion of the CRIA+ minor subset of A/J mice was observed (100x). No such enhancement was observed in BALB/c mice similarly treated. Manipulated BALB/c mice presented a higher frequency of CRIA+ anti-Ars B cells than naive or antigen-immunized BALB/c individuals.

Ion Bombardment Effect on the Hardness of Ti(C,N,O) Films Prepared by Ion Beam Controlled Deposition (IBCD)

1992 ◽  
Vol 279 ◽  
Author(s):  
Chen Youshan ◽  
Sun Yilin ◽  
Zhang Fumin ◽  
Mou Haichuan ◽  
Tao Wei ◽  
...  
Keyword(s):  
Film Formation ◽  
Ion Beam ◽  
Ion Bombardment ◽  
Advanced Technology ◽  
Preferential Growth ◽  
Ion Energy ◽  
Lattice Constants ◽  
Film Hardness ◽  
Pure Compounds ◽  
Controlled Deposition

Ion beam controlled deposition (IBCD) or ion beam assisted deposition (IB AD) of Ti(C,N,O) films has been investigated much in the last decade for both the advantage of this advanced technology and the promising properties of such materials. Ti(C,N,O) films are various solid solutions of interstitial compounds TiC, TiN and TiO of F.C.C structure with lattice constants lying between the values of the pure compounds. Some content of oxygen improves their wear resistance due to the lower fn;e enthalpies of such films in comparison with pure TiC and TiN films [1]. Many so-synthesizcd titanium carbide and titanium nitride films reported in published papers were actually of this sort as they often had more or less oxygen content from residual gas in vacuum. A number of papers were contributed to depict the texture and composition dependence of film on the arrival ratio of assisting ions versus deposited atoms (AR) as well as their mechanical properties [2–6]. However, the film formation mechanism in IBCD isn't quite clear yet, especially for cases with assisting ion energy of several to tens of keV. During a course to synthesize Ti(C,N,O) films by IBCD with the two beam technique, datum were accumulated. Based on a part of it, a previous paper on ion beam governed preferential growth in IBCD has been published [7]. This paper was aimed to search for the origin of ion bombardment effect on film hardness.

Analysis of Defects in Heavily-Doped MBE-GaAs

1982 ◽  
Vol 14 ◽  
Author(s):  
C.B. Carter ◽  
D.M. Desimone ◽  
H.T. Griem ◽  
C.E.C. Wood
Keyword(s):  
Liquid Phase ◽  
Molecular Beam ◽  
Type Material ◽  
Grown Layer ◽  
Defect Clusters ◽  
Complex Defect ◽  
Heavily Doped ◽  
Rich Material ◽  
P Type ◽  
Very High

ABSTRACTGaAs Has Been Grown By Molecular-Beam Epitaxy (MBE) With Large Concentrations (∼1018CM−2) Of Sn, Si, Ge, And Mn As Dopants. The Heavily-Doped N-Type Material Has Been Found To Contain Regions Of A Very High Dislocation Density. An Analysis Of The Less Complex Defect Areas Shows That The Dislocations Originate In The MBE-Grown Layer. These Observations And Others On More Complex Defect Clusters Are Compared With Recent Studies Of Defects In Material Grown By Liquid Phase Epitaxy (LPE). The More Heavily Doped P-Type Material Contains Discs Of Mn-Rich Material At The Surface Of The MBEgrown Epilayer. Both The Structure And Composition Of These Regions Have Been Examined.

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