Deterministic placement of doping atoms on silanol surfaces for ultimate devices

With the everlasting shrinking of semiconductor devices, the randomness of dopant distribution within a device becomes more likely to critically impact the performance of the latter. The aim of this work is to validate a silicon doping strategy through a controlled positioning of molecules in place of conventional implantations in order to limit the variability of the threshold tension. In contrast to previous works, doping atoms were directly grafted onto a thin silica layer and not onto a bare silicon surface. Here, we chose to control both site density and positioning by combining the control of site anchoring density and the use of sterically hindered molecules to yield a finely structured doped surface. This was carried out by first optimizing this approach by studying the grafting of boron compounds with ligands of various sizes and symmetries on the surface silanols of non - porous amorphous silica partially treated at high temperatures (700 °C) as a model system. This allowed obtaining a fully characterization of surface species through combined analytical techniques (IR-DRIFT, solidstate multi-core NMR and elemental analyses). The ligands were then eliminated by a thermal treatment, yielding surface boronic acids characterized by IR-DRIFT and NMR with optimal density (> 96%, 6.7*1013 B.cm-²). This technology was then successfully transferred to silicon wafers covered with native silica as evidenced by ICPMS analyses of the grafted oxide layer removed in HF droplet (VPD). Subsequent high temperature annealing step without capping in order to trigger diffusion of boron was then validated on silicon wafers using ICPMS in HF-dipped oxide and in silicon by TofSIMS profile measurements. Such treatment led to a dopant concentration in the silicon matrix equivalent to that reported in the literature (e.g. direct grafting on silicon and cap during annealing). Electrical analyses by tunnel spectroscopy showed the efficiency of the annealing step and confirmed the dopant amount in the surface layer of the silicon wafer

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Source https://theses.hal.science/tel-00908954
Author Mathey, Laurent
Maintainer CCSD
Last Updated May 8, 2026, 02:21 (UTC)
Created May 8, 2026, 02:21 (UTC)
Identifier NNT: 2012LYO10235
Language en
Rights https://about.hal.science/hal-authorisation-v1/
contributor Laboratoire de Chimie, Catalyse, Polymères et Procédés, UMR 5265 (C2P2) ; Université Claude Bernard Lyon 1 (UCBL) ; Université de Lyon-Université de Lyon-École Supérieure de Chimie Physique Électronique de Lyon (CPE)-Institut de Chimie - CNRS Chimie (INC-CNRS)-Centre National de la Recherche Scientifique (CNRS)
creator Mathey, Laurent
date 2012-11-05T00:00:00
harvest_object_id 05910ecb-df13-409e-a78f-974d99b28edc
harvest_source_id 3374d638-d20b-4672-ba96-a23232d55657
harvest_source_title test moissonnage SELUNE
metadata_modified 2026-03-31T00:00:00
set_spec type:THESE