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We study the origin of bimodal emission in AlGaN/AlN QD superlattices displaying a high internal quantum efficiency (around 50%) in the 230–300 nm spectral range. The secondary emission at longer wavelengths is linked to the presence of cone-like domains with deformed QD layers, which originate at the first AlN buffer/superlattice interface and propagate vertically. The cones originate at a 30°-faceted shallow pit in the AlN, which appears to be associated with a threading dislocation that produces strong shear strain. The cone-like structures present Ga enrichment at the boundaring facets and larger QDs within the conic domain. The bimodality of the luminescence is attributed to the differing dot size and composition within the cones and at the faceted boundaries, which is confirmed by the correlation of microscopy results and Schro¨dinger–Poisson calculations.

Gate oxide patterning during integrated circuits manufacturing can be defined by a photolithography and wet etch sequence. Wet etching process can be at risk. Indeed, during this step, liquid molecules can penetrate through resist layer to reach and damage the underlying material. The key parameter to know is the maximum duration that a given resist can ensure an effective protection. This study shows in the first time how to evaluate etching molecules diffusion thanks to ATR-FTIR technology and a gravimetric approach. Then a two-steps diffusion model has been established. Finally, differences are observed between four different commercial resists.

InGaAs and InP layers were treated by using Ar and He direct plasmas coupled with wet chemical treatments. InP surfaces are more sensitive to the various treatments than the InGaAs ones. Suitable and efficient treatments have been proposed to offer a good compromise between impact on surface and native oxide removal. We have demonstrated that concentrated HCl solution cleanings followed by He direct plasma treatment are efficient for the removal of InGaAs native oxides whereas He plasma exposure combined to a diluted HCl solution cleaning is more suitable for InP surfaces.

The effect of several treatments such as CMP or plasma activation applied to deposited silicon oxide layer surfaces prior to direct bonding has been investigated. It is shown that these treatments have a direct impact on surface and near subsurface OH bond densities which greatly participate to bonding energy changes. Better understanding of mechanism is proposed even if some conditions still deserve more investigation.

The wafer direct bonding technique is very sensitive to surface adsorbed water; hence it is a useful way to characterize the impact of wafer drying. We have focused this work on the drying impact on surfaces after innovative solvent exposure, in a liquid or in a vapor phase, compared with standard isopropyl alcohol drying: we report characterization results from different techniques investigating both native and thermal oxide surfaces. We report promising drying through low surface tension solvent exposure, especially in a vapor phase.

Multiple Internal Reflection (MIR) FTIR is used to assess the impact of potentially damaging BEOL integration process steps such as Chemical Mechanical Polishing (CMP) and NH3-based plasmas on a k=2.55 porous interlayer dielectric. The NH3 plasma is found to be very damaging, and a He plasma prior to the same NH3 plasma leads to a damage reduction. The impact of CMP is also confirmed and leads to an equivalent k-value degradation as a He + NH3 plasma. In order to reduce the integration damage, the addition of a low-k protective cap layer (k=3.3) is proposed. The required thickness to avoid impact from CMP and NH3-based plasmas is found to be 10 nm after CMP (Kstack=2.60 with 10 nm cap). As a result, those process steps are no longer a concern with this integration route.

Hf-Sc-O thin films were deposited at 500{degree sign}C on p-type Si(100)/SiO2 substrates by metal organic chemical vapour deposition. Hf(OtBu)2(mmp)2 and Sc(3mod)3 were used as precursors. The mixture of the precursors in a same solution leads to a rather low Sc incorporation. From XRD and ATR, it is found that the addition of a few percent of Sc (1 to 2 %) leads to the stabilization of the cubic phase. From plane-views TEM, the films are nanocrystallised, with an average grain size of 10 nm. The C(V) measurements on MOS structures show that the relative permittivity is maximum at ~ 1 to 2 % at. Sc in the films (epsilon ~ 25).

To pursue the device capability improvement, new materials have to be introduced in the gate stack. TiN metal gate on HfO2 is one of the solutions to replace existing gate. Thus, manufacturing processes, such as resist stripping, have to be adapted to these new materials as current processes can not be compatible. HfO2 compatibility was first studied by ellipsometry and ATR measurements, showing that Downstream type plasma (DS) with He-H2 or H2-N2 gas mix for dry processes, and Hydrozone (HZ) for wet processes were fully compatible. Then TiN compatibility was investigated by WDXRF and XPS. Results indicate that the same processes as for HfO2 are compatible with TiN. Finally, effectiveness study proved that DS He-H2 or H2-N2 plasmas were similar to O2 plasma. To fully remove the polymers, HZ processes or derivatives have to be performed after plasmas.

In non-volatile memories, high-k materials such as Al2O3, HfO2, and hafnium aluminates are good candidates as interpoly layers. In order to decrease the parasitic trapping of the interpoly stack, the effect of post deposition nitridation (PDN) on different high-k films was investigated. Several characterizations were performed on those films such as Angle Resolved X-ray Photo-electron Spectroscopy (AR-XPS), Auger Electron Spectroscopy (AES), Attenuated Total Reflection - Fourier Transform Infrared spectroscopy (ATR-FTIR) and Vacuum UltraViolet Spectroscopy Ellipsometry (VUV-SE). A correlation between the nitrogen incorporation and the crystallization was demonstrated. Al-rich films remain amorphous after PDN, with an incorporation of nitrogen in the film volume. Meanwhile, Hf-rich films crystallized after PDN, with nitrogen incorporated only at the high-k / Si substrate interface. Also nitrogen increases the crystallization temperature onset, which leads to a reduction of charge trapping after high temperature spike anneals. Nitrided amorphous hafnium aluminate films are good candidates as interpoly layer.

Vibration modes of cryogenically H-implanted germanium in the specific case of cryogenic implantation were detected by Fourier transform IR spectroscopy. Multiple internal reflection apparatuses were used; this optical configuration allowed enough sensitivity to detect small absorption bands. By making an analogy with the "well-known" silicon modes, hydrogenated interstitial and multivacancy defects and hydrogen-terminated were identified. The peaks at ( after annealing) and ( after annealing) can be attributed to modes in germanium, those at ( after annealing) and ( after annealing) to , those at ( after annealing) to , and those at to .