Doping of silicon by phosphorus end-terminated polymers: drive-in and activation of dopants

Perego, Michele; Caruso, Francesco; Seguini, Gabriele; Arduca, Elisa; Mantovan, R.; Sparnacci, Katia; Laus, Michele

doi:10.1039/d0tc01856b

Cited by 18 publications

(13 citation statements)

References 46 publications

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“…‰, Figure C2). Our method offers the same information as for dopant distributions that have been studied for bulk materials, for example, n-type semiconductors. − We further confirmed these results with the good agreement of those obtained from XPS by comparing the estimated penetration-depth to the inelastic mean-free path information depth (error <5%, Figure S7 and Table S3). …”

Section: Resultssupporting

confidence: 75%

High-Throughput Sizing, Counting, and Elemental Analysis of Anisotropic Multimetallic Nanoparticles with Single-Particle Inductively Coupled Plasma Mass Spectrometry

et al. 2022

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Nanoparticles (NPs) have wide applications in physical and chemical processes, and their individual properties (e.g., shape, size, and composition) and ensemble properties (e.g., distribution and homogeneity) can significantly affect the performance. However, the extrapolation of information from a single particle to the ensemble remains a challenge due to the lack of suitable techniques. Herein, we report a high-throughput single-particle inductively coupled plasma mass spectrometry (SP-ICP-MS)-based protocol to simultaneously determine the size, count, and elemental makeup of several thousands of (an)isotropic NPs independent of composition, size, shape, and dispersing medium with atomistic precision in a matter of minutes. By introducing highly diluted nebulized aqueous dispersions of NPs directly into the plasma torch of an ICP-MS instrument, individual NPs are atomized and ionized, resulting in ion plumes that can be registered by the mass analyzer. Our proposed protocol includes a phase transfer step for NPs synthesized in organic media, which are otherwise incompatible with ICP-MS instruments, and a modeling tool that extends the measurement of particle morphologies beyond spherical to include cubes, truncated octahedra, and tetrahedra, exemplified by anisotropic Cu NPs. Finally, we demonstrate the versatility of our method by studying the doping of bulk-dilute (<1 at. %) CuAg nanosurface alloys as well as the ease with which ensemble composition distributions of multimetallic NPs (i.e., CuPd and CuPdAg) can be obtained providing different insights in the chemistry of nanomaterials. We believe our combined protocol could deepen the understanding of macroscopic phenomena involving nanoscale structures by bringing about a statistics renaissance in research areas including, among others, materials science, materials chemistry, (nano)physics, (nano)photonics, catalysis, and electrochemistry.

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Section: Resultssupporting

confidence: 75%

High-Throughput Sizing, Counting, and Elemental Analysis of Anisotropic Multimetallic Nanoparticles with Single-Particle Inductively Coupled Plasma Mass Spectrometry

et al. 2022

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“…From the point of view of the target application, these data highlight that, even taking into account all these phenomena, the proposed approach guarantees a high level of control on the dopant concentration in the δ-layer. In previous papers, Perego et al showed excellent control of the doping level in silicon substrates by means of thermal diffusion of P atoms from dopant sources created via grafting of phosphorus end-terminated polymers. ,, The proposed doping approach relies on the main assumption that, taking advantage of the self-limiting nature of the “grafting to” process from the melt, proper selection of the polymer M n guarantees precise control of the areal dose and spatial distribution of dopants. Present work indicates that the effective grafting density of the polymer chains onto the Si substrate is not fully controlled by the selection of the M n , but it is somehow affected by the polydispersity of the phosphorus end-terminated polymers that are used to create the brush layer.…”

Section: Discussionmentioning

confidence: 99%

“…A cumulative and stepwise increase in the dose of P atoms grafted to the silicon surface is demonstrated by simple iteration of grafting/ashing cycles. 27,29,30 Upon deposition of a SiO 2 layer to prevent P outgassing, P atoms were efficiently injected into the Si substrate by high-temperature thermal treatments, demonstrating high activation rates (80%) of injected P atoms. 29 From this point of view, the proposed doping technology present several advantages compared to other polymer-assisted doping approaches that have been proposed by other groups in the literature.…”

Section: ■ Introductionmentioning

confidence: 99%

“…27,29,30 Upon deposition of a SiO 2 layer to prevent P outgassing, P atoms were efficiently injected into the Si substrate by high-temperature thermal treatments, demonstrating high activation rates (80%) of injected P atoms. 29 From this point of view, the proposed doping technology present several advantages compared to other polymer-assisted doping approaches that have been proposed by other groups in the literature. 31−34 In particular, the self-limiting nature of the brush layer formation guarantees a more accurate and reliable control over the dose of phosphorus atoms in the dopant source and a precise localization of the source with P atoms forming a δ-layer embedded into the SiO 2 matrix with negligible carbon contaminations.…”

Section: ■ Introductionmentioning

confidence: 99%

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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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“…[8][9][10] In addition to sub-10 nm junction depth, tailorable molecular structures of the polymer enable access to tens-of-nanometer patterning by leveraging self-assembly instead of photolithography. [13,14] Current efforts have been devoted to extending polymeric doping to a variety of molecular architectures, including dendrimers, [15,16] brushes, [17][18][19] and micelles. [9] While the dendrimer and brush approaches have demonstrated control of the dose by changing molecular weight, spatial patterning is limited to a micrometer length scale.…”

Section: Introductionmentioning

confidence: 99%

Discrete, Shallow Doping of Semiconductors via Cylinder‐Forming Block Copolymer Self‐Assembly

Zhang

Danielsen

Popere

et al. 2022

Macro Materials & Eng

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Block copolymer (BCP) self-assembly-assisted doping for semiconductors is used to achieve discrete doping with nanometer-scale junction depth, high throughput, and large area coverage. As devices become smaller and more sophisticated, spatial control of dopants becomes more critical. A variety of doping methods, such as monolayer doping and 𝜹-doping, have been developed to replace the conventional doping method, ion-implantation; however, lateral patterning of dopants relies on photo-or e-beam lithography. To address these challenges, a self-assembling dopant (boron)-containing BCP is designed to directly pattern dopants on the nanometer scale. This method skips the lithography step and is compatible with directed self-assembly approaches. The effect of the boron concentration in the BCP on the doping performance is systematically studied by changing the volume fraction of the boron-containing block while keeping the domain spacing and the mesoscale morphology constant. Successful self-assembly of the BCP into a hexagonally packed cylindrical morphology is confirmed by small-angle X-ray scattering and resonant soft X-ray scattering with a 26 nm cylinder-to-cylinder distance. Doping silicon using these BCPs enables discrete doped areas with shallow (7-13 nm) junction depth as demonstrated by the depth profile of boron, and supported by a sheet resistance study.

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Doping of silicon by phosphorus end-terminated polymers: drive-in and activation of dopants

Abstract: An effective doping technology for precise control of P atom injection and activation into a semiconductor substrate is presented.

Cited by 18 publications

References 46 publications

High-Throughput Sizing, Counting, and Elemental Analysis of Anisotropic Multimetallic Nanoparticles with Single-Particle Inductively Coupled Plasma Mass Spectrometry

High-Throughput Sizing, Counting, and Elemental Analysis of Anisotropic Multimetallic Nanoparticles with Single-Particle Inductively Coupled Plasma Mass Spectrometry

Silicon Doping by Polymer Grafting: Size Distribution Matters

Discrete, Shallow Doping of Semiconductors via Cylinder‐Forming Block Copolymer Self‐Assembly

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