Materials 2022, 15, 7886. https://doi.org/10.3390/ma15227886 www.mdpi.com/journal/materials Article Comprehensive Analysis of Phosphorus-Doped Silicon Annealed by Continuous-Wave Laser Beam at High Scan Speed Rasheed Ayinde Taiwo 1 , Joong-Han Shin 1,2, * and Yeong-Il Son 1 1 Department of Future Convergence Engineering, Kongju National University, Cheonan 31080, Korea 2 Department of Mechanical and Automotive Engineering, Kongju National University, Cheonan 31080, Korea * Correspondence: jhshin@kongju.ac.kr; Tel.: +82-41-521-9254; Fax: +82-41-555-9123 Abstract: We report an in-depth analysis of phosphorus (P)-doped silicon (Si) with a continuous-wave laser source using a high scan speed to increase the performance of semiconductor devices. We sys- tematically characterized the P-doped Si annealed at different laser powers using four-point probe resistance measurement, transmission electron microscopy (TEM), secondary-ion mass spectroscopy, X-ray diffractometry (XRD), and atomic force microscopy (AFM). Notably, a significant reduction in sheet resistance was observed after laser annealing, which indicated the improved electrical properties of Si. TEM images confirmed the epitaxial growth of Si in an upward direction without a polycrystal- line structure. Furthermore, we observed the activation of P without diffusion, irrespective of the laser power in the secondary-ion mass-spectrometry characterization. We detected negligible changes in lattice spacing for the main (400) XRD peak, showing an insignificant effect of the laser annealing on the strain. AFM images of the annealed samples in comparison with those of the as-implanted sample showed that the laser annealing did not significantly change the surface roughness. This study pro- vides an excellent heating method with high potential to achieve an extremely low sheet resistance without diffusion of the dopant under a very high scan speed for industrial applications. Keywords: laser annealing; phosphorous (P)-doped Si; electrical property; epitaxial growth; diffusion; surface roughness 1. Introduction Phosphorus (P)-doped silicon substrates (Sub-Si) are widely used in the manufactur- ing of advanced semiconductor materials owing to their excellent electrical properties. However, there are numerous drawbacks associated with the ion implantation process, including damage to the crystal lattice during ion bombardment and subsequent transient enhanced diffusion caused by defects during postannealing. The P atoms become incorporated at Si substitutional sites, generating strain in Sub-Si. This strain in the semiconductor channel is responsible for the carrier mobility enhancement, which can be increased by increasing the P concentration [1–5]. A large P concentration on a Sub-Si is electrically inactive, which requires a laser annealing process for activation. The acti- vation of dopants is essential to enhance the electrical properties of the fabricated material. Although various studies have been carried out on P-doped Si to achieve a low sheet resistance by ion implantation and postannealing [6–8], the traditional method causes dif- fusion of dopants into the substrate, which weakens the electrical properties of Si [9–11]. Considering these problems, laser annealing is being investigated as an alternative to an- neal P-doped Si with higher temperatures and simultaneously reduce the diffusion with a shorter annealing time [12–14]. The demand for high-performance devices and novel materials is driving the expansion of laser-based applications. For example, laser-pro- cessed thin films can be used to form local contact openings or passivate Si surfaces Citation: Taiwo, R.A.; Shin, J.-H.; Son, Y.-I. Comprehensive Analysis of Phosphorus-Doped Silicon Annealed by Continuous-Wave Laser Beam at High Scan Speed. Materials 2022, 15, 7886. https://doi.org/10.3390/ma15227886 Academic Editor: Andres Sotelo Received: 30 September 2022 Accepted: 3 November 2022 Published: 8 November 2022 Publisher’s Note: MDPI stays neu- tral with regard to jurisdictional claims in published maps and institu- tional affiliations. Copyright: © 2022 by the authors. Li- censee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and con- ditions of the Creative Commons At- tribution (CC BY) license (https://cre- ativecommons.org/licenses/by/4.0/).