Pt redistribution in N-MOS transistors during Ni salicide process

Atom probe tomography was used to study the redistribution of platinum during Ni(10 at.%Pt) silicidation of n-doped polycrystalline Si. These measurements were performed after the two annealing steps of standard salicide process both on a field-effect transistor and on unpatterned region submitted to the same process. Very similar results are obtained in unpatterned region and in transistor gate contact. The first phase to form is not the expected δ-Ni2Si but the non stoichiometric θ-Ni2Si. Pt redistribution is strongly influenced by this phase and the final distribution is different from what is reported in literature. © 2013 Elsevier B.V. All rights reserved.

Excellent oxidation endurance of boron nitride nanotube field electron emitters

Boron nitride nanotubes (BNNTs) are considered as a promising cold electron emission material owing to their negative electron affinity. BNNT field emitters show excellent oxidation endurance after high temperature thermal annealing of 600 °C in air ambient. There is no damage to the BNNTs after thermal annealing at a temperature of 600 °C and also no degradation of field emission properties. The thermally annealed BNNTs exhibit a high maximum emission current density of 8.39mA/cm2 and show very robust emission stability. The BNNTs can be a promising emitter material for field emission devices under harsh oxygen environments. © 2014 AIP Publishing LLC.

Ni(Pt)-silicide contacts on CMOS devices: Impact of substrate nature and Pt concentration on the phase formation

Ni silicides used as contacts in source/drain and gate of advanced CMOS devices were analyzed by atom probe tomography (APT) at atomic scale. These measurements were performed on 45 nm nMOS after standard self-aligned silicide (salicide) process using Ni(5 at.% Pt) alloy. After the first annealing (RTA1), δ-Ni2Si was the only phase formed on gate and source/drain while, after the second annealing (RTA2), two different Ni silicides have been formed: NiSi on the gate and δ-Ni2Si on the source and drain. This difference between source/drain and gate regions in nMOS devices has been related to the Si substrate nature (poly or mono-crystalline) and to the size of the contact. In fact, NiSi seems to have difficulties to nucleate in the narrow source/drain contact on mono-crystalline Si. The results have been compared to analysis performed on 28 nm nMOS where the Pt concentration is higher (10 at.% Pt). In this case, θ-Ni2Si is the first phase to form after RTA1 and NiSi is then formed at the same time on source (or drain) and gate after RTA2. The absence of the formation of NiSi from δ-Ni 2Si/Si(1 0 0) interface compared to θ-Ni2Si/Si(1 0 0) interface could be related to the difference of the interface energies. The redistributions of As and Pt in different silicides and interfaces were measured and discussed. In particular, it has been evidenced that Pt redistributions obtained on both 45 and 28 nm MOS transistors correspond to respective Pt distributions measured on blanket wafers. © 2013 Elsevier B.V. All rights reserved.

Physicochemical characteristics and droplet impact dynamics of superhydrophobic carbon nanotube arrays.

The physicochemical and droplet impact dynamics of superhydrophobic carbon nanotube arrays are investigated. These superhydrophobic arrays are fabricated simply by exposing the as-grown carbon nanotube arrays to a vacuum annealing treatment at a moderate temperature. This treatment, which allows a significant removal of oxygen adsorbates, leads to a dramatic change in wettability of the arrays, from mildly hydrophobic to superhydrophobic. Such change in wettability is also accompanied by a substantial change in surface charge and electrochemical properties. Here, the droplet impact dynamics are characterized in terms of critical Weber number, coefficient of restitution, spreading factor, and contact time. Based on these characteristics, it is found that superhydrophobic carbon nanotube arrays are among the best water-repellent surfaces ever reported. The results presented herein may pave a way for the utilization of superhydrophobic carbon nanotube arrays in numerous industrial and practical applications, including inkjet printing, direct injection engines, steam turbines, and microelectronic fabrication.

Increased carbon nanotube area density after catalyst generation from cobalt disilicide using a cyclic reactive ion etching approach

We used a cyclic reactive ion etching (RIE) process to increase the Co catalyst density on a cobalt disilicide (CoSi2) substrate for carbon nanotube (CNT) growth. Each cycle of catalyst formation consists of a room temperature RIE step and an annealing step at 450 °C. The RIE step transfers the top-surface of CoSi2 into cobalt fluoride; while the annealing reduces the fluoride into metallic Co nanoparticles. We have optimized this cyclic RIE process and determined that the catalyst density can be doubled in three cycles, resulting in a final CNT shell density of 6.6 × 10 11 walls·cm-2. This work demonstrates a very effective approach to increase the CNT density grown directly on silicides. © 2014 AIP Publishing LLC.