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In this study, we conduct a comparative analysis of single-beam laser annealing (SBLA) and dual-beam laser annealing (DBLA) techniques for semiconductor manufacturing. In the DBLA approach, two laser beams were precisely aligned to simultaneously heat a phosphorus-doped silicon (Si) wafer. The main objective was to investigate the impact of the two annealing techniques on the electrical properties, crystalline structure, and diffusion profile of the treated phosphorus-doped Si at equivalent laser powers. Both SBLA and DBLA improved the electrical properties of the phosphorus-doped Si, evidenced by increased carrier concentration and reduced carrier mobility. Additionally, the crystalline structure of the phosphorus-doped Si showed favorable modifications, with no defects and improved crystallinity. While both SBLA and DBLA produced similar phosphorus profiles with no significant redistribution of dopants compared to the as-implanted sample, DBLA achieved a higher activation ratio than SBLA. Although the results suggest improved dopant activation with minimal diffusion, further studies are needed to clearly confirm the effect of DBLA on dopant activation and diffusion. [ABSTRACT FROM AUTHOR]

As gallium oxide-based heterojunction devices gain prominence, low-resistance contacts to aluminum gallium oxide material are of increasing importance for high performance and access to modulation doped layers. Here, the activation of ion-implanted silicon donors is investigated as a function of donor density from 5 × 1018 cm−3 to 1 × 1020 cm−3, activation anneal duration from 6 s to 600 s, and activation temperature from 900°C to 1140°C. Importantly, ohmic behavior was achievable across a reasonably wide process window at moderate to high doping concentrations. Specific contact resistance of 1 × 10−3 Ω cm2 and sheet resistance of 2.8 kΩ/□ were achieved for a 60 nm-deep 1 × 1020 cm−3 box implant after activation at 1000°C for 6 s with standard Ti/Au contacts. Under these conditions, an activation efficiency of 7% was observed with Hall mobility of ~32 cm2/Vs. Furthermore, we demonstrate a Schottky diode formed of implanted material with a rectification ratio > 106 and further confirm the Hall carrier density results using capacitance–voltage profiling analysis. Finally, we show the significant impact of anneal duration and the potential for deleterious over-annealing which reduces the active carrier density, mobility, and resultant material conductivity. [ABSTRACT FROM AUTHOR]

Carrier (electron) compensation is an important issue in impurity (donor) doped ZnO thin films, which must be understood to achieve the desired electrical conductivity. Unprecedentedly, using trivalent Al, tetravalent Ti, and pentavalent Vanadium, (the atomic symbol is not used to avoid confusion with the conventional vacancy symbol) metal ion doping in ZnO thin films while keeping all the growth and annealing parameters similar, we demonstrate that donor–acceptor (D-A) compensation in the doped film is influenced largely by the dopant valence. Hall data show a drastic decrease in the conductivity and carrier concentration values indicating progressively more D-A compensation as the dopant valence increases. Post-growth annealing in special ambient recovers trapped free carriers due to dopants' activation. The activation of the dopants due to annealing in Ar + 10% H2 + excess Zn ambient is far more than that happened in only Ar + 10% H2 ambient. To support this, we further discuss the dark and photo-Hall electrical transport data of the as-grown and annealed films measured under sub-bandgap photo-excitations to release the electrons from the acceptor-like complexes. [ABSTRACT FROM AUTHOR]

The bit density is generally increased by stacking more layers in 3D NAND Flash. Lowering dopant activation of select transistors results from complex integrated processes. To improve channel dopant activation, the test structure of vertical channel transistors was used to investigate the influence of laser thermal annealing on dopant activation. The activation of channel doping by different thermal annealing methods was compared. The laser thermal annealing enhanced the channel activation rate by at least 23% more than limited temperature rapid thermal annealing. We then comprehensively explore the laser thermal annealing energy density on the influence of Poly-Si grain size and device performance. A clear correlation between grain size mean and grain size sigma, large grain size mean and sigma with large laser thermal annealing energy density. Large laser thermal annealing energy density leads to tightening threshold voltage and subthreshold swing distribution since Poly-Si grain size regrows for better grain size distribution with local grains optimization. As an enabler for next-generation technologies, laser thermal annealing will be highly applied in 3D NAND Flash for better device performance with stacking more layers, and opening new opportunities of novel 3D architectures in the semiconductor industry. [ABSTRACT FROM AUTHOR]

Differential Hall Effect Metrology (DHEM) technique was used to characterize highly n-type doped Si epi layers deposited on p-type Si wafers. Total dopant concentration, doping depth profile and post deposition annealing condition were changed for various sample sets and influence of such changes on the resistivity, mobility and carrier concentration depth profiles were studied. It was determined that samples annealed at 900 °C had higher activation compared to those annealed at 700 °C. Gradation in doping depth profiles did not result in similar gradation in resistivity values. Carrier concentration at the near-surface region was found to be lower in all samples. It is shown that electrical properties of films forming ultra-shallow junctions can be studied in detail and correlated with process parameters using DHEM data obtained at sub-nm depth resolution.

The state-of-the-art CMOS technology has started to adopt three-dimensional (3D) integration approaches, enabling continuous chip density increment and performance improvement, while alleviating difficulties encountered in traditional planar scaling. This new device architecture, in addition to the efforts required for extracting the best material properties, imposes a challenge of reducing the thermal budget of processes to be applied everywhere in CMOS devices, so that conventional processes must be replaced without any compromise to device performance. Ultra-violet laser annealing (UV-LA) is then of prime importance to address such a requirement. First, the strongly limited absorption of UV light into materials allows surface-localized heat source generation. Second, the process timescale typically ranging from nanoseconds (ns) to microseconds (μs) efficiently restricts the heat diffusion in the vertical direction. In a given 3D stack, these specific features allow the actual process temperature to be elevated in the top-tier layer without introducing any drawback in the bottom-tier one. In addition, short-timescale UV-LA may have some advantages in materials engineering, enabling the nonequilibrium control of certain phenomenon such as crystallization, dopant activation, and diffusion. This paper reviews recent progress reported about the application of short-timescale UV-LA to different stages of CMOS integration, highlighting its potential of being a key enabler for next generation 3D-integrated CMOS devices. [ABSTRACT FROM AUTHOR]

The bit density is generally increased by stacking more layers in 3D NAND Flash. Lowering dopant activation of select transistors results from complex integrated processes. To improve channel dopant activation, the test structure of vertical channel transistors was used to investigate the influence of laser thermal annealing on dopant activation. The activation of channel doping by different thermal annealing methods was compared. The laser thermal annealing enhanced the channel activation rate by at least 23% more than limited temperature rapid thermal annealing. We then comprehensively explore the laser thermal annealing energy density on the influence of Poly-Si grain size and device performance. A clear correlation between grain size mean and grain size sigma, large grain size mean and sigma with large laser thermal annealing energy density. Large laser thermal annealing energy density leads to tightening threshold voltage and subthreshold swing distribution since Poly-Si grain size regrows for better grain size distribution with local grains optimization. As an enabler for next-generation technologies, laser thermal annealing will be highly applied in 3D NAND Flash for better device performance with stacking more layers, and opening new opportunities of novel 3D architectures in the semiconductor industry.

Heavily doped epitaxial films with an active dopant concentration over 1 × 1021/cm3 in the source/drain regions are key requirements for advanced metal-oxide-semiconductor field-effect transistors (MOSFETs) with ultralow contact resistance. In this study, we investigated the microstructure, strain characteristic, and electrical property with dopant behavior of heavily in-situ B-doped (ISBD) SiGe films (chemical B concentration >3 × 1021 atoms/cm3) treated by nanosecond laser annealing (NLA). The lattice parameters of the B-doped SiGe films considerably decreased in the regrown regions because of increased substitutional B concentrations. The substitutional B atoms decreased the accumulated strain energy per unit area of the regrown regions, leading to epitaxial regrowth of B-doped SiGe film without strain relaxation. Additionally, electrical analyses demonstrated that the active B concentrations in the regrown regions increased above 3 × 1021 atoms/cm3. In the unmelted region, the active B concentrations were close to that of the as-grown film, which was similar to the relative ratio of the active and inactive states in the B 1s spectra measured through X-ray photoelectron spectroscopy (XPS). Our results revealed that nonsubstitutional B atoms in the as-grown heavily ISBD SiGe films were converted into substitutional B atoms and activated in the recrystallized region via NLA. [ABSTRACT FROM AUTHOR]

[Display omitted] • The NLA treatment prevents undesired dopant-diffusion and removes defects induced by ion-implantation in the near-surface region, effectively achieving highly active B concentration over approximately 1021 cm−3. • Using XPS, new chemical bonding states related to Si-B and Ge-B bonds in the near-surface region were identified in XPS Si 2 p and Ge 3 d spectra, which show the substitutionality of B-atoms upon NLA process. • Based on the depth profiles of the B 1 s peaks from the surface to melted depth, the relative ratios of active state in the NLA-treated films were confirmed and compared with the electrical activation rate measured by Hall measurements. Given that transistor dimensions are approaching atomic scale in metal–oxide–semiconductor field-effect-transistors (MOSFETs), attaining low-contact resistivity (ρ c) between contact-metal and Si is a primary challenge for source/drain (S/D) fabrications. To reduce ρ c , it is necessary to increase active dopant concentration in the semiconductor region underneath the contact-metal. High-dose ion-implantation and nanosecond laser-annealing (NLA) have been intensively investigated to produce highly activated layers in S/D regions. Particularly for the B-doped SiGe layers, which are used as S/D stressor for p-MOSFETs, non-substitutional B species are generated in the highly doped films at concentrations exceeding ∼ 1021 cm−3. These non-substitutional B are electrically non-activated and thus should be minimized to reduce ρ c. In this study, we investigated the chemical states and electrical activation in highly B-doped SiGe layer. Using X-ray photoelectron spectroscopy (XPS), we examined the substitutionality of B-atoms and identified new chemical states of Si-B and Ge-B bonds in Si 2 p and Ge 3 d peaks. In the B 1 s spectra, electrical activation states are determined by quantifying relative area ratios of the active/inactive B peaks, which are well matched with activation rates calculated by Hall measurements. Our findings systematically explained the activation behavior of NLA-treated B-doped SiGe films in high B-concentration ranges. [ABSTRACT FROM AUTHOR]

In this work an extensive characterization over XeCl multishot laser irradiation was performed at different energy densities and with different thicknesses of graphitic coating superimposed on P and Al implanted 4H–SiC epitaxial layers. It was noted that at 0.6 J/cm2 the 180 nm coating provides a smooth surface unlike lower thicknesses or uncoated treatments. The μ-Raman investigation showed the crystalline quality as a function of the energy density. Through Medium Angle Annular Dark Field-Scanning Transmission Electron Microscopy (MAADF-STEM) and High Angle Annular Dark Field (HAADF)-STEM investigations, the absence of extended defects and the presence of regions with higher density of carbon interstitials (C i) was revealed. Circular Transfer Length Method (CTLM) measurements demonstrated how irradiation at 0.9 J/cm2 succeeded to reach values of (7.28 ± 1.15) × 102 Ω/sq, lower than the findings achieved with furnace treatment at 1650 °C. However, electrical characterization carried out through μ-Raman investigation over the Folded Transverse Acoustic (FTA) modes showed consistent activation of the order of 7 × 1019 cm−3 at 0.6 J/cm2 while exhibited CTLM extracted sheet resistance of (3.17 ± 0.06) × 104 Ω/sq. Therefore, this work highlights the contrast between fast processes as the accommodation and ionization of dopant atoms in substitutional positions and slow processes such as the recovery of ion implantation damage. By offering faster processing rates, lower thermal budgets, and high spatial control over the annealing process, laser annealing on 4H–SiC as a post-implantation thermal treatment approach presents several advantages over conventional annealing methods. This study marks a significant progress in comprehending and improving the effectiveness of laser annealing on 4H–SiC. [Display omitted] [ABSTRACT FROM AUTHOR]

This study reports the comprehensive investigation of the green laser annealing (GLA) technique for phosphorus (P)-doped silicon (Si). The aim of this study was to examine the suitability of GLA in improving the properties of P-doped Si for semiconductor devices. This study explored the electrical, chemical, and crystalline characteristics of P-doped Si under major laser-annealing conditions. Multiple characterization techniques, including the four-point probe method, Hall effect measurement, transmission electron microscopy (TEM), secondary ion mass spectroscopy (SIMS), X-ray diffraction (XRD), and atomic force microscopy (AFM), were used to investigate the interaction between the laser beam and P-doped Si under different laser annealing conditions. A considerable decrease in the sheet resistance, carrier mobility, and Hall resistance and an increase in the carrier concentration of the material were observed after GLA. The TEM images indicated a transition from partial polycrystallization to complete crystallization with epitaxial growth, depending on the GLA conditions. The SIMS data showed low P diffusion in the depth direction of the Si and relatively uniform P concentrations near the surface of the Si after annealing. Furthermore, XRD analysis revealed no considerable changes in the lattice spacing for the main (400) XRD peak, confirming insignificant strain effects from GLA. AFM analysis showed a minimal increase in the surface roughness compared to that of the as-implanted sample, indicating that GLA did not significantly alter the surface morphology of the material. GLA is a promising method for enhancing the electrical properties of P-doped Si without considerable dopant diffusion or changes in the atomic structure, making it suitable for industrial applications. [ABSTRACT FROM AUTHOR]

Aluminum-doped zinc oxide (AZO) films have been synthesized using reactive high power impulse magnetron sputtering (HiPIMS) in a wide range of Al contents, 0.6–14.7 at.%. The film structure and microstructure investigated by X-ray diffraction and transmission electron microscopy evolves from nanocrystalline columnar film towards ultrafine nanocrystalline films of wurtzite ZnO structure upon increasing the Al content. Electrical properties measured by 4-point probe and Hall effect setups revealed that effective doping maybe achieved up to 3 at.% Al by using HiPIMS. Most importantly, optical transmittance and electronic structure measurements at the Al L 2,3 of electron energy loss near edge structure (ELNES) contain signatures of dopant activation, and dopant segregation that may serve to investigate on the origin of electrical properties degradation and to optimize the electrical properties of AZO films. • Al-doped ZnO films synthesized by reactive HiPIMS of preserved wurtzite structure up to 14.7 at.% Al • Increasing the dopant content above 1 at.% Al decreases the crystallinity. • High density of charge carriers is induced by Al doping up to 3 at.% Al. • Al contents above 3 at.% inactivate a significant fraction of Al dopant. • Electronic structure at the Al L 2,3 edge can be used to extract the fractions of active/inactive Al dopant. [ABSTRACT FROM AUTHOR]