A Test Structure to Characterize Nano-Scale Ohmic Contacts in III-V MOSFETs

ABSTRACTLow resistance ohmic contacts for silicon devices commonly incorporate silicide materials as part of the contact. The electrical characterisation of ohmic contacts requires the use of various test structures such as the Cross Kelvin Resistor in order to determine the specific contact resistance ρc. This paper describes the results of using a three-dimensional finite element model of a Kelvin Resistor test structure in order to determine the influence of the electrical and geometrical parameters of a silicide-well on the magnitude of ρc. The same model of the test structure is further used to model the current density in the contact region. The results indicate that the presence of a silicide-well leads to reduced values of both ρc and the current density.

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Investigation about I-V Characteristics in a New Electronic Structure Model of the Ohmic Contact for Future Nano-Scale Ohmic Contact

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.470.43 ◽

2011 ◽

Vol 470 ◽

pp. 43-47

Author(s):

Yukihiro Takada ◽

Masakazu Muraguchi ◽

Tetsuo Endoh ◽

Shintaro Nomura ◽

Kenji Shiraishi

Keyword(s):

Electronic Structure ◽

Ohmic Contact ◽

Ohmic Contacts ◽

Structure Model ◽

Discrete Level ◽

Fundamental Physics ◽

Device Scaling ◽

Nano Scale ◽

Proposed Model ◽

Device Applications

Ohmic contacts are crucial for both device applications and the study of fundamental physics. From the perspective of device scaling trends, nano-scale Ohmic contacts are indispensable for future LSI technologies such as metallic source and drain contacts. In this study, we investigate the I-V characteristics using a varying discrete level distribution based on our previously-proposed model. Our calculated results show that linear I-V properties can be obtained from uniform discrete level distributions.

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Two-contact Circular Test Structure for Determining Specific Contact Resistivity

MRS Proceedings ◽

10.1557/opl.2013.864 ◽

2013 ◽

Vol 1553 ◽

Author(s):

Y. Pan ◽

G. K. Reeves ◽

P. W. Leech ◽

P. Tanner ◽

A. S. Holland

Keyword(s):

Ohmic Contacts ◽

Electrical Characterization ◽

Contact Resistivity ◽

Test Structure ◽

Metal Contacts ◽

Circular Test ◽

Specific Contact ◽

Specific Contact Resistivity ◽

Analytical Expressions ◽

Geometrical Dimensions

ABSTRACTAs ohmic contacts decrease in size and approach nanoscale dimensions, accurate electrical characterization is essential, requiring the development of suitable test structures for this task. We present here a new test structure derived from the standard three-contact circular transmission line model (CTLM) [1], for determining the specific contact resistivity of ohmic contacts. This test structure minimizes sources of error which arise from the CTLM by – (i) reducing the number of contacts within one test pattern from three to two, (ii) ensuring the assumption of equipotential metal contacts used in modelling is more easily attained experimentally, and (iii) allowing the fabrication of reduced geometrical dimensions essential for determining low specific contact resistivity values. The analytical expressions are presented and experiment results are undertaken to demonstrate the accuracy of the technique. There are no error corrections required for determining contact parameters using the presented test structure.

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Microstructural Characterization of Au-Ge-Ni based ohmic contacts to GaAs/AlGaAs modfet device

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100126433 ◽

1987 ◽

Vol 45 ◽

pp. 326-327

Author(s):

A.K. Rai ◽

A.K. Petford-Long ◽

A. Ezis ◽

D.W. Langer

Keyword(s):

Contact Resistance ◽

Ohmic Contact ◽

Ohmic Contacts ◽

Microstructural Characterization ◽

Almost Everywhere ◽

Spacer Layer ◽

Good Contact ◽

The Relationship ◽

Lower Contact

Considerable amount of work has been done in studying the relationship between the contact resistance and the microstructure of the Au-Ge-Ni based ohmic contacts to n-GaAs. It has been found that the lower contact resistivity is due to the presence of Ge rich and Au free regions (good contact area) in contact with GaAs. Thus in order to obtain an ohmic contact with lower contact resistance one should obtain a uniformly alloyed region of good contact areas almost everywhere. This can possibly be accomplished by utilizing various alloying schemes. In this work microstructural characterization, employing TEM techniques, of the sequentially deposited Au-Ge-Ni based ohmic contact to the MODFET device is presented.The substrate used in the present work consists of 1 μm thick buffer layer of GaAs grown on a semi-insulating GaAs substrate followed by a 25 Å spacer layer of undoped AlGaAs.

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Microstructure of sputter deposited Ni-Sb ohmic contacts on GaAs

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100154226 ◽

1989 ◽

Vol 47 ◽

pp. 450-451

Author(s):

S. Yegnasubramanian ◽

V.C. Kannan ◽

R. Dutto ◽

P.J. Sakach

Keyword(s):

High Performance ◽

Ohmic Contacts ◽

Surface Defects ◽

Pure Metal ◽

Device Fabrication ◽

Native Oxide ◽

Metal Thin Films ◽

Recent Developments ◽

Different Temperatures ◽

Sputter Deposited

Recent developments in the fabrication of high performance GaAs devices impose crucial requirements of low resistance ohmic contacts with excellent contact properties such as, thermal stability, contact resistivity, contact depth, Schottky barrier height etc. The nature of the interface plays an important role in the stability of the contacts due to problems associated with interdiffusion and compound formation at the interface during device fabrication. Contacts of pure metal thin films on GaAs are not desirable due to the presence of the native oxide and surface defects at the interface. Nickel has been used as a contact metal on GaAs and has been found to be reactive at low temperatures. Formation Of Ni2 GaAs at 200 - 350C is reported and is found to grow epitaxially on (001) and on (111) GaAs, but is shown to be unstable at 450C. This paper reports the investigations carried out to understand the microstructure, nature of the interface and composition of sputter deposited and annealed (at different temperatures) Ni-Sb ohmic contacts on GaAs by TEM. Attempts were made to correlate the electrical properties of the films such as the sheet resistance and contact resistance, with the microstructure. The observations are corroborated by Scanning Auger Microprobe (SAM) investigations.

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