Pierre Caubet

Low-Temperature Low-Resistivity PEALD TiN Using TDMAT under Hydrogen Reducing Ambient

Titanium nitride (TiN) films were deposited using plasma-enhanced atomic layer deposition (PEALD) from the organometallic precursor tetrakis-dimethyl-amino-titanium (TDMAT) with hydrogen (H 2 ) as a coreactant. Low-resistivity values lying from 210 to 275 μΩ cm were achieved for 10 nm thick films deposited at low temperature: 150°C. The effects of temperature, plasma time, and plasma power were investigated. It was demonstrated that the chemical reaction is complementary and self-limiting. A minimum energy is necessary to reach the low-resistivity plateau. Chemical and physical properties of the films are also reported and a surface reaction mechanism is proposed. It is suggested that after TDMAT chemisorption to the surface, amines are removed by hydrogen radicals, and at the same time, titanium carbide bonds (Ti-C) are formed. The low resistivity results from the presence of Ti 2 C or Ti 2 N phases in the PEALD TiN film. The industrial viability of this process was also evaluated on 300 mm wafers. Good performances were obtained on wafer-to-wafer uniformity and step coverage, while some improvements related to the within-wafer uniformity are required.

Reliable 3D damascene MIM architecture embedded into Cu interconnect for a Ta 2 O 5 capacitor record density of 17 fF/μm 2

A new simple 3D Damascene architecture requiring only one additional mask is introduced for high-density MIM capacitors. TiN/Ta₂O₅/TiN stack deposited by PEALD has been integrated between Cu interconnect levels to maximize quality factor Q, reaching up to 17 fF/μm² capacitance. High-performance, breakdown voltages over 15 V and good linearity, C₁ = 76 ppm/V and C₂ = 63 ppm/V² at 100 kHz, make this capacitor an unique solution for analog and RF applications embedded in Cu BEOL.

Impact of TaN/Ta copper barrier on full PEALD TiN/Ta2O5/TiN 3D damascene MIM capacitor performance

MIM capacitors are widely integrated for RF and analog applications. A high density full PEALD TiN/Ta2O5/TiN capacitor is integrated among copper interconnect following an innovative 3D damascene architecture. The impact of a TaN/Ta layer, introduced to avoid Cu diffusion, on both TiN electrode properties and integrated MIM stack performance is studied. Unexpected lower current was obtained without the barrier layer. As a result, up to 17 fF/mum2 capacitance densities were achieved with breakdown voltage over 15 V and excellent voltage linearity.

Effective work function engineering by sacrificial lanthanum diffusion on HfON-based 14 nm NFET devices

In this paper, the impact of metallic lanthanum (La) deposited by Radio-Frequency PVD on effective work function (WFeff) of HfON-based NFET devices in a sacrificial metal gate-first approach is evaluated for the first time. Engineering of WFeff towards N+ without leakage degradation is demonstrated by tuning both the pedestal TiN thickness and the as-deposited metallic La dose. WFeff shift is related to a La-induced interfacial dipole (5), whose value has been correlated to the effective La dose into HfON/SiON stack after diffusion annealing, which has been accurately measured through a spectroscopic method based on La X-Ray Fluorescence (XRF).

Gate-last integration on planar FDSOI MOSFET: Impact of mechanical boosters and channel orientations

We present for the first time Gate-Last (GL) planar Fully Depleted (FD) SOI MOSFETs featuring both ultra thin silicon body (3-5 nm) and BOX (25 nm). Transistors with metal-last on high-k first (TiN/HfSiON) have been successfully fabricated down to 15nm gate length. We have thoroughly characterized the gate stack (reliability, work-function tuning on Equivalent Oxide Thickness EOT=0.85nm) and transport (hole mobility, Raccess) for different surface and channel orientations. We report excellent ION, p=1020μA/μm at IOFF, p=100nA/μm at VDD=0.9V supply voltage for <;110> pMOS channel on (001) surface with in-situ boron doped SiGe Raised Source and Drain (RSD) and compressive CESL. This is explained by the high efficiency of the strain transfer into the ultra-thin channel, as evidenced by physical strain measurements (dark field holography).

3D Atomic Scale Analysis of CMOS type structures for 14 nm UTBB-SOI technology

As the dimensions of microelectronic devices are progressively reduced new architectures and materials are being introduced to try and meet ever stricter performance criteria. The use of high-k dielectrics (hafnium based oxides) can reduce leakage current leading to better electrical properties. The coupling of these dielectrics with metallic gate materials (TiN) has led to structures of greater complexity in CMOS (complementary metal oxide semiconductor) devices. Due to current dimensions (a few nanometres) atom probe tomography (APT) is one of the very few techniques which can give 3D chemical information at this scale [1-2]. But due to the insulating and high evaporation field nature of these materials analysis is often difficult, with very low analysis yields, or even impossible [3].

PECVD RF versus dual frequency: an investigation of plasma influence on metal?organic precursors' decomposition and material characteristics

Plasma enhanced metal organic chemical vapor deposition (PEMOVCD) of titanium nitride with dual frequency plasma sources were studied by means of plasma and material characterization. Adding a low frequency to a radio frequency plasma in order to enhance the deposition reaction mechanism is demonstrated. An in depth investigation of plasma by optical emission spectroscopy shows that due to secondary electrons heating the plasma, it enters a gamma-mode and that LF permits better dissociation of the H2 reactant gas. Moreover, it appears that the TiN metal organic precursor is not completely dissociated (no Ti* emission) but new species are observed that indicate a different fragmentation of the precursor. When LF plasma is used these modifications can be correlated to a change in the deposition reaction mechanism which affects the properties of the deposited material. Strong modifications of the TiN properties and deposition rate are observed when adding 17–60 W LF to a 200 W RF plasma. For example, with 35 W LF added to a 200 W RF, the deposition rate is increased by a factor two and the film appears to be less resistive (by 50%) and has a higher density. Such effects are not observed when only increasing the RF power (from 200 to 300 W with no LF power).

Investigation of TiN thin film oxidation depending on the substrate temperature at vacuum break

Due to the reduction of the thickness of the layers used in the advanced technology nodes, there is a growing importance of the surface phenomena in the definition of the general properties of the materials. One of the least controlled and understood phenomenon is the oxidation of metals after deposition, at the vacuum break. In this study, the influence of the sample temperature at vacuum break on the oxidation level of TiN deposited by metalorganic chemical vapor deposition is investigated. TiN resistivity appears to be lower for samples which underwent vacuum break at high temperature. Using X-ray photoelectron spectrometry analysis, this change is correlated to the higher oxidation of the TiN layer. Moreover, angle resolved XPS analysis reveals that higher is the temperature at the vacuum break, higher is the surface oxidation of the sample. This surface oxidation is in turn limiting the diffusion of oxygen in the volume of the layer. Additionally, evolution of TiN layers resistivity was monitored in ...