Advances in ultrashallow doping of silicon

Zhang, Chufan; Chang, Shannan; Dan, Yaping

doi:10.1080/23746149.2020.1871407

Cited by 8 publications

(9 citation statements)

References 76 publications

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“…Additionally, ultrathin films of Sb could potentially find application for in situ n-doping of semiconductor materials such as silicon. In recent years, monolayer doping (MLD) has been developed as a method for doping silicon or germanium with group 15 (or group 13) elements. − This method involves surface functionalization with a monolayer of a dopant-containing molecule, followed by application of a capping layer such as SiO 2 (to minimize loss of dopant atoms to the surroundings during the next step), rapid thermal annealing to cause diffusion of the chemisorbed dopant atoms into the semiconductor material, and removal of the capping layer. MLD can enable ultrashallow doping and doping of 3-D structures without crystal damage.…”

Section: Introductionmentioning

confidence: 99%

“…MLD can enable ultrashallow doping and doping of 3-D structures without crystal damage. However, several drawbacks of MLD have been noted, including (a) almost all of the molecules used for monolayer formation contain carbon, leading to inevitable carbon incorporation into the semiconductor, in some cases significantly deactivating the electrical activity of the dopant atoms, ,, (b) dopant concentrations higher than those provided by a monolayer of dopant-containing molecules are not readily achieved, , and (c) monolayer formation typically requires prolonged reaction with the dopant-containing molecule (liquid or in solution) at elevated temperature . ALD-fabricated ultrathin films of group 15 elements could potentially circumvent these issues, providing (via thermal annealing) access to films with high dopant concentrations and minimal carbon contamination.…”

Section: Introductionmentioning

confidence: 99%

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Room-Temperature Atomic Layer Deposition of Elemental Antimony

Hareri

Emslie

2022

Chem. Mater.

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Atomic layer deposition (ALD) of elemental antimony was achieved on hydrogen-terminated silicon (H–Si) and SiO2/Si substrates using Sb(SiMe3)3 and SbCl3 in the temperature range 23–65 °C. The mirrorlike films were confirmed to be composed of crystalline antimony by XPS (for the film deposited at 35 °C) and XRD, with low impurity levels and strong preferential orientation of crystal growth relative to the substrate surface. To the best of our knowledge, this is the first example of room-temperature thermal ALD (with demonstrated self-limiting growth) of a pure element. Film growth at 35 °C exhibited a substrate-enhanced mechanism, characterized by faster film growth for the first ∼125 ALD cycles, where substantial deposition occurs on the original substrate surface (GPC = 1.3 Å/cycle on SiO2/Si and 1.0 Å/cycle on H–Si) and slower film growth (GPC = 0.40 Å/cycle on SiO2/Si and 0.27 Å/cycle on H–Si) after ∼125 cycles, once much of the initial substrate surface has been covered. Films deposited using 500–2000 ALD cycles were shown to be continuous by SEM. The use of less than 250 cycles afforded discontinuous films. However, in this initial growth phase, when the deposition occurs primarily on the original substrate surface, in situ surface pretreatment by Sb(SiMe3)3 or SbCl3 (50 × 0.4 or 0.8 s pulses) followed by the use of longer precursor pulses (0.4 or 0.8 s) during the first 50 ALD cycles resulted in improved nucleation. For example, on H–Si, a continuous 6.7 nm thick film was produced after initial pretreatment with 50 × 0.8 s pulses of SbCl3, followed by 50 ALD cycles using 0.8 s pulses. The use of longer pulses in the first 50 ALD cycles following surface pretreatment is likely required to achieve complete reactivity with an increased density of reactive surface sites.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Room-Temperature Atomic Layer Deposition of Elemental Antimony

Hareri

Emslie

2022

Chem. Mater.

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“…For instance, arylphosphonic acids have been used to engineer the electronic properties of atomically thin sheets of semiconducting transition-metal dichalcogenides . Doping of silicon and other bulk semiconductors has been achieved by means of SAM of P-containing molecules in the so called monolayer doping approach. ,,− This approach relies on the formation of a SAM over the semiconductor surface and subsequent injection of the dopant into the substrate by a high-temperature thermal treatment. The described procedure has been used to enable the formation of sub 5 nm ultrashallow junctions in Si. , Interesting exploitation perspectives are also expected for photovoltaic applications, which usually require effective approaches to reduce the cost of the devices .…”

Section: Introductionmentioning

confidence: 99%

Silicon Doping by Polymer Grafting: Size Distribution Matters

Perego¹,

Kuschlan

Seguini³

et al. 2021

ACS Appl. Polym. Mater.

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Phosphorus δ-layers in SiO 2 have been prepared by means of poly(methyl methacrylate) (PMMA), terminated with a phosphoruscontaining moiety acting as an anchoring group. In particular, grafting of two P-terminated PMMA samples with M n = 7.5 kg/mol (D̵ = 1.14) and M n = 17.8 kg/mol (D̵ = 1.23) onto 10 nm thick SiO 2 films deposited on Si substrates has been investigated, focusing on the thickness evolution of the brush layer as a function of the processing parameters, that is, annealing temperature and time. Upon removal of the polymer chains and subsequent encapsulation into a SiO 2 matrix, the concentration of phosphorus atoms into the P δ-layers has been monitored by time-of-flight secondary ion mass spectrometry. The effective P dose in the P δ-layer is mainly dictated by the molecular weight of the P-terminated PMMA, and the doping process results are highly reproducible, provided that tight control over the experimental protocol is granted. However, although the grafting density is expected to progressively increase as a function of annealing time with a linear correlation between grafting density and thickness, the measured P dose in the δ-layers is observed to follow the opposite trend. This effect has been accounted for by considering a distortion of the molecular weight distribution of the grafted species with respect to the initial molecular weight distribution of the polymer. The overall picture reveals important information about the mechanism and dynamics governing the "grafting to" process of P-terminated PMMA polymers onto nondeglazed Si substrates.

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“…Low energy ion irradiation and ion implantation of solids becomes increasingly important due to the advances in ultra-low energy ion implantation of two-dimensional (2D) materials [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16], implantation of shallow junctions [17][18][19][20] and the broad applied field of ion erosion [21][22][23][24][25]. Ion energies required for doping of 2D materials are as low a 20 eV.…”

Section: Introductionmentioning

confidence: 99%

Low energy ion-solid interactions: a quantitative experimental verification of binary collision approximation simulations

Hofsäss,

Junge,

Kirscht

et al. 2023

Mater. Res. Express

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Ultra-low energy ion implantation has become an attractive method for doping of two-dimensional materials and ultra-thin films. The new dynamic Monte Carlo program IMINTDYN based on the binary collision approximation allows a reliable prediction of low energy implantation profiles and target compositional changes, as well as efficient simulation of high energy light ion scattering. To demonstrate the quality of these predictions and simulations, we present a model case experiment where we implanted W ions into tetrahedral amorphous carbon with low (10 keV) and ultra-low (20 eV) ion energies and analyzed the W implantation profiles with high resolution Rutherford backscattering spectrometry (HR-RBS). This experiment is compared with a complete simulation of all aspects of ion-solid-interactions of the experiment using the new IMINTDYN program. A unique novel simulation option, also relevant for implantation into 2D materials, is the inclusion of the vacancy as target species with dynamic vacancy generation and annihilation. Whereas simulations neglecting vacancy formation cannot reproduce the measured implantation profiles, we find excellent agreement between simulated and measured HR-RBS spectra. We also demonstrate the important role of simultaneous weak collisions in the binary collision approximation at low projectile energies.

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Advances in ultrashallow doping of silicon

Cited by 8 publications

References 76 publications

Room-Temperature Atomic Layer Deposition of Elemental Antimony

Room-Temperature Atomic Layer Deposition of Elemental Antimony

Silicon Doping by Polymer Grafting: Size Distribution Matters

Low energy ion-solid interactions: a quantitative experimental verification of binary collision approximation simulations

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