Measuring The Work Functions Of PVD TaN, TaSiN And TiSiN Films With A Schottky Diode CV Technique For Metal Gate CMOS Applications

2002 ◽  
Vol 745 ◽  
Author(s):  
James Pan ◽  
Christy Woo ◽  
Minh-Van Ngo ◽  
Bryan Tracy ◽  
Ercan Adem ◽  
...  
Keyword(s):  
Work Function ◽  
Nitrogen Content ◽  
Schottky Diode ◽  
Metal Gate ◽  
Promising Candidate ◽  
Auger Analysis ◽  
Metal Work Function ◽  
Work Functions ◽  
Metal Work

ABSTRACTThe metal gate process becomes a promising candidate for sub-65nm CMOS, due to the elimination of polysilicon depletion effects, and the possibility of adjusting the CMOS threshold voltage without more threshold implants. Our goal is to process mteal films with tunable work functions, in order to meet the demand of sub-65nm metal gate CMOS.PVD TaN films are deposited with various processing conditions. Auger analysis shows that by changing the nitrogen flow rate and the plasma power, the nitrogen content in the TaN films can be adjusted. In order to accurately determine the work function of these TaN materials, we have developed a Schottky Diode CV technique (or Metal-Silicon CV, or MS-CV). This approach not only improves the accuracy of the metal work function measurement, compared with the traditional MOS-CV technique (which is affected by the thickness and quality of the oxide), but also simplifies the fabrication.With the MS-CV's, we have successfully measured the work functions of Ni and Co, and compared the data with published references. The work function of PVD TaN actually decreases with higher nitrogen content, according to the Auger data and the MS-CV measurement, ranging from 3.42 – 4.20 Volts. The MS-CV technique is shown to be independent to the size of the capacitors, and is little affected by the measurement frequency. By changing the frequency from 100KHz to 1MHz, the error in the work function is less than 50mV.

Adsorption of self-assembled monolayer on Cu(111): First-principles study

2017 ◽  
Vol 31 (24) ◽  
pp. 1750198
Author(s):  
Jian Wang ◽  
Jiang-Tao Cheng ◽  
Shang-Yi Ma ◽  
Hong-De Wang
Keyword(s):  
Work Function ◽  
First Principles ◽  
Function Theory ◽  
Self Assembled Monolayer ◽  
Effective Technique ◽  
Adsorption Sites ◽  
Metal Work Function ◽  
Surface Adsorbates ◽  
Work Functions ◽  
Metal Work

The density function theory is used to explore the structures of alkyl-thiolate (RS, R=CH3, CF3) monolayer on the Cu(111) surface. By performing the total energy calculations for RS at three possible adsorption sites (fcc, hcp, bridge) with five different coverages (1/12, 1/9, 1/6, 1/4, 1/3), we obtained the stable adsorption configurations of the Cu–RS system. Especially, the effect of Van der Waals interaction on the adsorption configurations was studied by the DFT-D2 method. The work functions for Cu–RS (R=CH3, CF3) systems were calculated, we find that the CH3S adsorbed on the Cu(111) surface decreases the metal work function remarkably, and the work functions strongly depend on the coverage. In the case of the Cu–CF3S system, the results are just the opposite. Thus, controlling the kind and coverage of the surface adsorbates would be an effective technique to tune the work function of the metal.

Investigations of Metal Gate Electrodes on HfO2 Gate Dielectrics

2004 ◽  
Vol 811 ◽  
Author(s):  
Jamie Schaeffer ◽  
Sri Samavedam ◽  
Leonardo Fonseca ◽  
Cristiano Capasso ◽  
Olubunmi Adetutu ◽  
...  
Keyword(s):  
Fermi Level ◽  
Work Function ◽  
Gate Dielectrics ◽  
Electrical Stability ◽  
Metal Gate ◽  
Fermi Level Pinning ◽  
Poly Silicon ◽  
Metal Work Function ◽  
The Impact ◽  
Metal Work

ABSTRACTAs traditional poly-silicon gated MOSFET devices scale, the additional series capacitance due to poly-silicon depletion becomes an increasingly large fraction of the total gate capacitance, excessive boron penetration causes threshold voltage shifts, and the gate resistance is elevated. To solve these problems and continue aggressive device scaling we are studying metal electrodes with suitable work-functions and sufficient physical and electrical stability. Our studies of metal gates on HfO2 indicate that excessive inter-diffusion, inadequate phase stability, and interfacial reactions are mechanisms of failure at source drain activation temperatures that must be considered during the electrode selection process. Understanding the physical properties of the metal gate – HfO2 interface is critical to understanding the electrical behavior of MOS devices. Of particular interest is Fermi level pinning, a phenomenon that occurs at metal – dielectric interfaces which causes undesirable shifts in the effective metal work function. The magnitude of Fermi level pinning on HfO2 electrodes is studied with Pt and LaB6 electrodes. In addition, the intrinsic and extrinsic contributions to Fermi level pinning of platinum electrodes on HfO2 gate dielectrics are investigated by examining the impact of oxygen and forming gas anneals on the work function of platinum-HfO2-silicon capacitors. The presence of interfacial oxygen vacancies or Pt-Hf bonds is believed to be responsible for a degree of pinning that is stronger than predicted from the MIGS model alone. Interface chemistry and defects influence the effective metal work function.

Effective Metal Work Function of High-Pressure Hydrogen Postannealed Pt–Er Alloy Metal Gate on HfO2Film

2007 ◽  
Vol 46 (1) ◽  
pp. 125-127 ◽  
Author(s):  
Cheljong Choi ◽  
Moongyu Jang ◽  
Yarkyeon Kim ◽  
Myungsim Jun ◽  
Taeyoub Kim ◽  
...  
Keyword(s):  
High Pressure ◽  
Work Function ◽  
Metal Gate ◽  
Metal Work Function ◽  
Metal Work ◽  
Alloy Metal ◽  
Pressure Hydrogen

Effect of Gate Metal Work-function on Junctionless (JL) Nanowire GAA MOSFET Performance

2021 ◽  
Author(s):  
Manoj Angara ◽  
Biswajit Jena ◽  
S. Rooban
Keyword(s):  
Work Function ◽  
Threshold Voltage ◽  
Drain Current ◽  
Potential Profile ◽  
Device Performance ◽  
Metal Gate ◽  
Metal Work Function ◽  
Current Threshold ◽  
Source Voltage ◽  
Metal Work

Abstract Metal gate technology is one of the promising methods used to increase the drain current by increasing the electrostatic controllability. Different metals have different work-function that controls the device performance very closely as gate to source voltage is the basic inputs for these. In this paper the dependency of gate metal work-function on device performance (both for nMOS and pMOS) is extensively investigated. The gate metal work-function value is taken as 4.2eV to 5.1eV with one increment to see the change in potential profile. With this condition, the IOn current, IOff current, threshold voltage, transconductance also calculated for these structures. A decrease value in drain current (1e-6 to 1e-7 A) is observed for both the cases with increase in work-function of gate metal. However, the Off current is getting better (1e-7 to 1e-18 A) while moving towards higher metal work-function values. As a result of which the IOn/IOff ratio increases which leads to higher device performances.

Two-terminal vertical thyristor using Schottky contact emitter to improve thermal instability

Nano Futures ◽  
2021 ◽  
Author(s):  
Min-Won Kim ◽  
Ji-Hun Kim ◽  
Jun-Seong Park ◽  
Byoung-Seok Lee ◽  
Sangdong Yoo ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Work Function ◽  
Thermal Instability ◽  
Schottky Contact ◽  
Memory Cell ◽  
Cross Point ◽  
Operation Temperature ◽  
Metal Work Function ◽  
Metal Work ◽  
Contact Metal

Abstract In a two-terminal-electrode vertical thyristor, the latch-up and latch-down voltages are decreased when the memory operation temperature of the memory cells increases, resulting in a severe reliability issue (i.e., thermal instability). This study fundamentally solves the thermal instability of a vertical-thyristor by achieving a cross-point memory-cell array using a vertical-thyristor with a structure of vertical n++-emitter, p+-base, n+-base, and p++-emitter. The vertical-thyristor using a Schottky contact metal emitter instead of an n++-Si emitter significantly improves the thermal stability between 293 and 373 K. Particularly, the improvement degree of the thermal stability is increased significantly with the use of the Schottky contact metal work function. Because the thermal instability (i.e., degree of latch-up voltage decrement vs. memory operation temperature) decreases with an increase in the Schottky contact metal work function, the dependency of the forward current density between the Schottky contact metal and p+-Si based on the memory operation temperature reduces with increase in the Schottky contact metal work function. Consequently, a higher Schottky contact metal work function produces a higher degree of improvement in the thermal stability, i.e., W (4.50 eV), Ti (4.33 eV), Ta (4.25 eV), and Al (4.12 eV). Further research on the fabrication process of a Schottky contact metal emitter vertical-thyristor is essential for the fabrication of a 3-D cross-point memory-cell.

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