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A pFET threshold-voltage (Vt) reduction of about 200 mV is demonstrated by inserting a thin Al2O3 layer between the high-K dielectric and the TiN gate without noticeable degradation of other electrical properties. HfSiOx capped with 9 Å of Al2O3 obtains a low long-channel Vt of —0.37 V (the lowest among those with TiN gate), a high mobility of 59 cm2 ⁄V · s at 0.8 MV/cm (92% of universal value), a negligible equivalent. oxide-thickness (EOT) increase of 0.1 Å (compared to the uncapped reference), and a low Vt instability of 4.8 mV at 7 MV/cm. It also passes the ten-year negative-bias-temperature-instability (NBTI) lifetime specification with a gate overdrive of —0.7 V. This indicates that Al2O3 caps are beneficial to the pFET applications. In contrast, nitrogen incorporation in the Al2O3-capped HfSiOx is not favorable because it increases the Vt by 50—140 mV, degrades the mobility by 10%-22%, increases the EOT by 0.5—0.8 Å and the Vt instability by 5–13 mV, and reduces the NBTI lifetime by four to five orders of magnitude. Compared to postcap nitridation, posthigh-k nitridation results in more severe degradation of these properties by incorporating nitrogen closer to the Si/SiO2 interface. [ABSTRACT FROM AUTHOR]

Conduction band-edge effective work functions (ϕm,eff) are demonstrated with TaCx and TiN by means of La2O3 capping of HfSiOx in a gate-first process flow with CMOS- compatible thermal budget. With TaCx, a 10-Å-thick La2O3 cap results in a ϕm,eff of 3.9 eV with a low equivalent oxide thickness (EOT) increase (1-2 Å) and unaffected electron mobility. With TiN, non-nitrided La2O3 capping results in a smaller ϕm,eff reduction at a larger EOT increase, while with post-cap nitridation, the TiN ϕm,eff is lower at a smaller EOT increase. Results show that the choice of metal and nitridation conditions have significant effects on La2O3 capped stacks. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we have studied the effect of boric acid (H3BO3) on the nucleation of nickel (Ni) nanoparticles on titanium nitride (TiN). We linked the potential transients during galvanostatic deposition to the different regimes of Ni deposition. The two most important regimes, i.e. nucleation and growth regime, were found to depend on the H3BO3 concentration. Indeed, by lowering the amount of H3BO3 the particle density increased (nucleation), while it also resulted in an earlier growth termination. Based on these findings, we propose a growth-inhibited nucleation model to explain the impact of H3BO3 on the formation of Ni nanoparticles. During Ni nucleation the surface pH increases due to local H+ reduction, leading to the formation and adsorption of Ni(OH)2 on the Ni particles. As a result, the growth of the particles is inhibited and new nucleation is promoted. The formation of this inhibiting hydroxide is counteracted by the presence of H3BO3 as it buffers the surface pH. Therefore, a higher particle density is obtained at low H3BO3 concentrations. However, when the concentration of H3BO3 is too low, Ni(OH)2 is already formed in the diffusion layer during the nucleation regime as the onset of H2O reduction occurs sooner. This results in the termination of Ni deposition before the nucleation of Ni is complete yielding almost no deposited Ni at the surface at low H3BO3 concentrations. Therefore, an optimum H3BO3 concentration is needed where the degree of growth-inhibition is high while Ni is still deposited for a sufficient amount of time. [Copyright &y& Elsevier]

In this paper, we show the electrochemicaldeposition of a subnanometerfilm of nickel (Ni) on top of titanium nitride (TiN). We exploit theconcept of cluster growth inhibition to enhance the nucleation ofnew nuclei on the TiN substrate. By deliberately using an unbufferedelectrolyte solution, the degree of nucleation is enhanced as growthis inhibited more strongly. This results in a very high particle densityand therefore an ultralow coalescence thickness. To prevent the terminationof Ni deposition that typically occurs in unbuffered solutions, theconcentration of Ni2+in solution was increased. We haveverified with RBS and ICP-MS that the deposition of Ni on the surfacein this case did not terminate. Furthermore, annealing experimentswere used to visualize the closed nature of the Ni film. The closureof the deposited film was also confirmed by TOF-SIMS measurementsand occurs when the film thickness is still in the subnanometer regime.The ultrathin Ni film was found to be an excellent catalyst for carbonnanotube growth on conductive substrates and can also be applied asa seed layer for bulk deposition of a smooth Ni film on TiN. [ABSTRACT FROM AUTHOR]

Abstract: Carbon nanotubes (CNTs) were integrated successfully into 150nm contact holes having a TiN underlayer and a Cu single damascene top contact module. All the integration steps for CNT integration, for patterning the Cu top contact and the mask-set used are compatible with 130nm device technologies on 200mm wafers. The first resistance yield plots for the CNT contacts on full wafer level are presented. For CNT grown at 540°C in contact holes with aspect ratio 1.3, a single CNT contact hole resistance of 3.4kΩ was achieved. The structure designed, the process flow presented here for CNT integration, and the automatic probing constitute a platform that allows benchmarking different recipes and process conditions. This constitutes a significant step forward towards the realization of a contact module with vertical CNT interconnects of superior quality. This is because the platform can speed up the learning cycle time for optimizing the CNT interconnect based on learning from the electrical performance. [Copyright &y& Elsevier]

Abstract: We propose to use carbon nanotube (CNT)–CNT contacts instead of CNT–metal contacts as a route towards low resistance CNT horizontal interconnects. We characterize by electrical transport measurements and Kelvin probe force microscopy the contacts present in CNT horizontal interconnects grown by chemical vapor deposition between titanium nitride electrodes. When two CNTs with diameter around 30nm grow from opposing electrodes and touch each other with their outermost shells, typical contact resistances around 16kΩ are obtained. The corresponding contact resistivity of about 14Ωμm2 is one order of magnitude smaller than the contact resistivity of a CNT touching the TiN surface with its outermost shell. On the other hand, the contact resistance of a CNT grown from a nickel catalyst particle deposited on a TiN electrode is negligibly small when compared to the above mentioned contact resistances. Our results demonstrate that we are able to grow from opposing electrodes CNTs that touch each other with a corresponding high density (up to 1011 cm−2) of CNT–CNT contacts. This may offer an effective solution towards the growth of low resistance CNT horizontal interconnects. [Copyright &y& Elsevier]

Abstract: In this study, we used oxygen to increase the work function of a TiN gated stack. To prevent the EOT growth associated with oxygen incorporation, we proposed a novel replacement gate flow, where oxygen incorporation by O2 anneal on a thin TiN layer was performed after dopant activation. With this novel flow, a maximum work function tuning range of ∼0.32eV was achieved without significant EOT penalty, making it attractive for p-type metal gate integration. [Copyright &y& Elsevier]