scholarly journals New Al-Ni-Ge Contacts on GaAs; Their Structure and Electrical Properties

1988 ◽  
Vol 126 ◽  
Author(s):  
Z. Liliental-Weber ◽  
J. Washburn ◽  
C. Musgrave ◽  
E. R. Weber ◽  
R. Zuleeg ◽  
...  
Keyword(s):  
Ohmic Contacts ◽  
Electrical Contact ◽  
Critical Factor ◽  
Contact Layer ◽  
Auger Spectroscopy ◽  
Semiconductor Surface ◽  
Chemical Cleaning ◽  
Tunneling Mechanism ◽  
Transmission Electron ◽  
Secondary Ion

ABSTRACTThe structure and composition of the recently developed Al-Ni-Ge ohmic contacts to n-GaAs were investigated by transmission electron microscopy combined with secondary ion mass spectroscopy (SIMS) and Auger spectroscopy. The semiconductor/metal-alloy interface of these contacts remain very flat after annealing (500°C, for 1 min - contact resistance 1.4×10−6Ωcm2), in contrast to the widely used Au-Ni-Ge contacts. The metal sequence during deposition is found to be a critical factor in determining the electrical contact properties and the dispersion of the oxide layer on the semiconductor surface after chemical cleaning. Ge doping of the GaAs beneath the contact layer was observed by SIMS, and a tunneling mechanism through the n+GaAs:Ge layer was proposed to explain the ohmic properties of the contacts.

Microstructural analysis of Pd-based ohmic contacts to p-type GaAs

1991 ◽  
Vol 6 (3) ◽  
pp. 553-559 ◽  
Author(s):  
K.M. Schmitz ◽  
K.L. Jiao ◽  
R. Sharma ◽  
W.A. Anderson ◽  
G. Rajeswaran ◽  
...  
Keyword(s):  
Ohmic Contacts ◽  
Broad Band ◽  
Microstructural Analysis ◽  
Composition Profile ◽  
Electrical Measurements ◽  
Cross Sectional ◽  
Transmission Electron ◽  
P Type ◽  
Ohmic Contact Formation ◽  
Secondary Ion

As part of the investigation of the use of Pd-based ohmic contacts to p-type GaAs, cross-sectional transmission electron microscopy, Auger electron spectroscopy, and secondary ion mass spectroscopy were used to explore the uniformity at the metal/GaAs interface and its composition profile after ohmic contact formation. Comparisons were made among Au:Be, Au:Be/Pd, and Au/Pd contacts. Regions of p+ were formed in n-type GaAs by a spin-on source which was rapid diffused at 950 °C for 6 s or by ion implantation at a dose of 3 × 1014 atoms/cm2 at 150 keV for 15 min. Metallizations were accomplished by evaporation with a base pressure of 3 × 10−6 Torr. Sintering of the metallizations was done in a furnace at 350 °C for 15 min. Cross-sectional transmission electron microscope studies revealed an absence of spiking when Be is present in the metallization scheme but a broad band diffused into GaAs. An improper metal/GaAs adhesion was observed when Pd is absent. Be assists in confining the reaction of Pd with GaAs and acts as a diffusion barrier to the p+ dopant. Electrical measurements, taken from transmission line and cross bridge Kelvin resistors, were best for the Pd/Au:Be, which yielded a contact resistance of 0.3 μΩ-cm2.

Utilizing Nanoprobing and Circuit Diagnostics to Identify Key Failure Mechanism of Otherwise Nonvisible Defects in 20 nm Logic Devices

2014 ◽  
Author(s):  
M.K. Dawood ◽  
C. Chen ◽  
P.K. Tan ◽  
S. James ◽  
P.S. Limin ◽  
...  
Keyword(s):  
Failure Analysis ◽  
Contact Layer ◽  
Fault Isolation ◽  
Tem Analysis ◽  
Logic Devices ◽  
Technology Advancement ◽  
Transmission Electron ◽  
Voltage Contrast ◽  
Almost All ◽  
20 Nm

Abstract In this work, we present two case studies on the utilization of advanced nanoprobing on 20nm logic devices at contact layer to identify the root cause of scan logic failures. In both cases, conventional failure analysis followed by inspection of passive voltage contrast (PVC) failed to identify any abnormality in the devices. Technology advancement makes identifying failure mechanisms increasingly more challenging using conventional methods of physical failure analysis (PFA). Almost all PFA cases for 20nm technology node devices and beyond require Transmission Electron Microscopy (TEM) analysis. Before TEM analysis can be performed, fault isolation is required to correctly determine the precise failing location. Isolated transistor probing was performed on the suspected logic NMOS and PMOS transistors to identify the failing transistors for TEM analysis. In this paper, nanoprobing was used to isolate the failing transistor of a logic cell. Nanoprobing revealed anomalies between the drain and bulk junction which was found to be due to contact gouging of different severities.

Effects of Concurrent Co or Ti Silicidation on Transient Diffusion and End-of-Range Damage in Phosphorus Implanted Silicon

1992 ◽  
Vol 262 ◽  
Author(s):  
J.W. Honeycutt ◽  
J. Ravi ◽  
G. A. Rozgonyi
Keyword(s):  
Secondary Ion Mass Spectrometry ◽  
Complete Removal ◽  
Dislocation Loops ◽  
Enhanced Diffusion ◽  
Depth Profiles ◽  
Enhanced Dissolution ◽  
Implantation Damage ◽  
Transmission Electron ◽  
Defect Behavior ◽  
Secondary Ion

ABSTRACTThe effects of Ti and Co silicidation on P+ ion implantation damage in Si have been investigated. After silicidation of unannealed 40 keV, 2×1015 cm-2 P+ implanted junctions by rapid thermal annealing at 900°C for 10–300 seconds, secondary ion mass spectrometry depth profiles of phosphorus in suicided and non-silicided junctions were compared. While non-silicided and TiSi2 suicided junctions exhibited equal amounts of transient enhanced diffusion behavior, the junction depths under COSi2 were significantly shallower. End-of-range interstitial dislocation loops in the same suicided and non-silicided junctions were studied by planview transmission electron microscopy. The loops were found to be stable after 900°C, 5 minute annealing in non-silicided material, and their formation was only slightly effected by TiSi2 or COSi2 silicidation. However, enhanced dissolution of the loops was observed under both TiSi2 and COSi2, with essentially complete removal of the defects under COSi2 after 5 minutes at 900°C. The observed diffusion and defect behavior strongly suggest that implantation damage induced excess interstitial concentrations are significantly reduced by the formation and presence of COSi2, and to a lesser extent by TiSi2. The observed time-dependent defect removal under the suicide films suggests that vacancy injection and/or interstitial absorption by the suicide film continues long after the suicide chemical reaction is complete.

Selective Area Deposition of Passivants, Insulators, and Epitaxial Films of II-VI Compound Semiconductors

1989 ◽  
Vol 161 ◽  
Author(s):  
D.L. Dreifus ◽  
Y. Lansari ◽  
J.W. Han ◽  
S. Hwang ◽  
J.W. Cook ◽  
...  
Keyword(s):  
Ohmic Contacts ◽  
Epitaxial Films ◽  
Semiconductor Surface ◽  
Epitaxial Layers ◽  
Double Crystal ◽  
Surface Areas ◽  
Selective Area ◽  
Lift Off ◽  
P Type ◽  
Area Deposition

ABSTRACTII-VI semiconductor surface passivants, insulators, and epitaxial films have been deposited onto selective surface areas by employing a new masking and lift-off technique. The II-VI layers were grown by either conventional or photoassisted molecular beam epitaxy (MBE). CdTe has been selectively deposited onto HgCdTe epitaxial layers as a surface passivant. Selective-area deposition of ZnS has been used in metal-insulator-semiconductor (MIS) structures. Low resistance ohmic contacts to p-type CdTe:As have also been realized through the use of selectively-placed thin films of the semi-metal HgTe followed by a thermal evaporation of In. Epitaxial layers of HgTe, HgCdTe, and HgTe-CdTe superlattices have also been grown in selective areas on CdZnTe substrates, exhibiting specular morphologies and double-crystal x-ray diffraction rocking curves (DCXD) with full widths at half maximum (FWHMs) as narrow as 140 arcseconds.

Oxygen Precipitation Along Individual Ion Tracks During High Dose O+ Implantation into Silicon

1987 ◽  
Vol 93 ◽  
Author(s):  
Witold P. Maszara
Keyword(s):  
Silicon Layer ◽  
High Dose ◽  
Regular Array ◽  
Ion Tracks ◽  
Oxygen Precipitation ◽  
Transmission Electron ◽  
Oxygen Gas ◽  
Kinetics Of ◽  
Secondary Ion ◽  
Lattice Matched

ABSTRACTSilicon wafers with and without protective1Ahermil oxide were implanted with oxygen at 150keV with doses 1.6 – 2.0×1018 cm−2. Transmission electron microscopy (TEM) and secondary ion mass spectroscopy (SIMS) were used to study the top silicon layer remaining above the implanted buried oxide. regular array of spheroidal voids filled with oxygen gas was observed only in the samples that were not protected by the oxide. The voids were aligned into individual columns whose crystallographic orientation with respect to the host silicon lattice matched the direction of the implantation. The origin and the kinetics of their formation are discussed.

Investigation of low- and high-resistance Ni–Ge–Au ohmic contacts to n+ GaAs using electron microbeam and surface analytical techniques

1996 ◽  
Vol 11 (5) ◽  
pp. 1244-1254 ◽  
Author(s):  
Nancy E. Lumpkin ◽  
Gregory R. Lumpkin ◽  
K. S. A. Butcher
Keyword(s):  
Electron Microscopy ◽  
Ohmic Contacts ◽  
Analytical Electron Microscopy ◽  
Depth Profiling ◽  
Analytical Techniques ◽  
Two Phase ◽  
Low Resistance ◽  
Fine Grained ◽  
Multiphase Microstructure ◽  
Transmission Electron

A process for the formation of low-resistance Ni–Ge–Au ohmic contacts to n+ GaAs has been refined using multivariable screening and response surface experiments. Samples from the refined, low-resistance process (which measure 0.05 ± 0.02 Ω · mm) and the unrefined, higher resistance process (0.17 ± 0.02 Ω · mm) were characterized using analytical electron microscopy (AEM), transmission electron microscopy (TEM), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), and x-ray photoemission spectroscopy (XPS) depth profiling methods. This approach was used to identify microstructural differences and compare them with electrical resistance measurements. Analytical results of the unrefined ohmic process sample reveal a heterogeneous, multiphase microstructure with a rough alloy-GaAs interface. The sample from the refined ohmic process exhibits an alloy which is homogeneous, smooth, and has a fine-grained microstructure with two uniformly distributed phases. XPS analysis for the refined ohmic process sample indicates that the Ge content is relatively depleted in the alloy (relative to the deposited Ge amount) and enriched in the GaAs. This is not evidenced in the unrefined ohmic process sample. Our data lead us to conclude that a smooth, uniform, two-phase microstructure, coupled with a shift in Ge content from the post-alloy metal to the GaAs, is important in forming low-resistance ohmic contacts.

Investigation of Ge, As, and Au Diffusion in Non-Alloyed Epitaxial Au-Ge Ohmic Contacts to n-GaAs Using Secondary Ion Mass Spectroscopy Backside Sputter Depth-Profiling

1991 ◽  
Vol 240 ◽  
Author(s):  
H. S. LEE ◽  
R. T. Lareau ◽  
S. N. Schauer ◽  
R. P. Moerkirk ◽  
K. A. Jones ◽  
...  
Keyword(s):  
Ohmic Contacts ◽  
Ion Beam ◽  
Depth Profiling ◽  
Depth Resolution ◽  
High Concentration ◽  
Ohmic Behavior ◽  
Preferential Sputtering ◽  
Specific Contact ◽  
Secondary Ion ◽  
Diffusion Profiles

ABSTRACTA SIMS backside sputter depth-profile technique using marker layers is employed to characterize the diffusion profiles of the Ge, As, and Au in the Au-Ge contacts after annealing at 320 C for various times. This technique overcomes difficulties such as ion beam mixing and preferential sputtering and results in high depth resolution measurements since diffusion profiles are measured from low to high concentration. Localized reactions in the form of islands were observed across the surface of the contact after annealing and were composed of Au, Ge, and As, as determined by SIMS imaging and Auger depth profiling. Backside SIMS profiles indicate both Ge and Au diffusion into the GaAs substrate in the isalnd regions. Ohmic behavior was obtained after a 3 hour anneal with a the lowest average specific contact resistivity found to be ∼ 7 × 100−6 Ω- cm2.

The Distribution of Phosphorus in Romano-British Ironwork

1990 ◽  
Vol 185 ◽  
Author(s):  
Alain E. Kaloyeros ◽  
Robert M. Ehrenreich
Keyword(s):  
Electron Microscopy ◽  
Electron Spectroscopy ◽  
Auger Electron ◽  
Materials Analysis ◽  
X Ray ◽  
Transmission Electron ◽  
Depth Study ◽  
Iron Artifacts ◽  
And Performance ◽  
Secondary Ion

AbstractPhosphorus is found to be a common impurity in many of the iron tools and weapons produced during the pre-Roman and Roman Iron Ages of Britain (600 BC - 300 AD). The effects of this impurity on the properties and performance of antiquarian materials is not well understood, however. This paper presents the initial findings of an in-depth study of the distribution, chemistry, and effects of phosphorus in Romano-British ironwork. For this purpose, two Romano-British iron artifacts from the site of Ircheoter, Northamptonshire, were examined using powerful techniques for archeological materials analysis that include electron microprobe, secondary ion mass spectroscopy (SIMS), transmission electron microscopy (TEM) with energydispersive x-ray spectroscopy capabilities (EDXS), and Auger electron spectroscopy (AES). It was found that phosphorous was indeed present in the artifacts. The phosphorus atoms were predominantly segregated at grain boundaries and thus should have led to a lowering of grain boundary cohesion and a degradation in the performance of the tools.

scholarly journals Applications of ToF-SIMS in surface chemistry analysis of lignocellulosic biomass: A review

BioResources ◽  
2016 ◽  
Vol 11 (2) ◽  
pp. 5581-5599
Author(s):  
Hong Yan Mou ◽  
Shubin Wu ◽  
Pedro Fardim
Keyword(s):  
Surface Chemistry ◽  
Lignocellulosic Biomass ◽  
Secondary Ion Mass Spectrometry ◽  
Critical Factor ◽  
Tof Sims ◽  
Biomass Components ◽  
Current Article ◽  
Sims Analysis ◽  
Secondary Ion

Time-of-flight secondary-ion mass spectrometry (ToF-SIMS) is an advanced surface-sensitive technique that can provide both spectral and imaging information about materials. Recently, ToF-SIMS has been used for advanced studies of lignocellulosic biomass. In the current article, the application of ToF-SIMS to the characterization of the surface chemical composition and distribution of biomass components in lignocelluloses is reviewed. Moreover, extended applications of ToF-SIMS in the study of pretreatments, modification of biomaterials, and enzyme activity of lignocellulosic materials are presented and discussed. Sample preparation prior to ToF-SIMS analysis and subsequent interpretation of results is a critical factor in ensuring reliable results. The focus of this review is to give a comprehensive understanding of and offer new hints about the effects of processing conditions on the surface chemistry of lignocellulosic biomass.

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