We describe challenges of the epitaxial Si-cap/Si0.75Ge0.25//Si-substrate growth process, in view of its application in 3D device integration schemes using Si0.75Ge0.25 as backside etch stop layer with a focus on high throughput epi processing without compromising material quality. While fully strained Si0.75Ge0.25 with a thickness >10 times larger than the theoretical thickness for layer relaxation can be grown, it is challenging to completely avoid misfit dislocations at the wafer edge during Si-growth on top of strained Si0.75Ge0.25, even for thinner Si0.75Ge0.25 layers and when growing the Si-cap layer at a lower temperature. Extremely sensitive characterization methods are mandatory to detect the extremely low density of misfit dislocations at the wafer edge. Light scattering measurements are most reliable. The epitaxial Si-cap/Si0.75Ge0.25//Si-substrate layer stacks are stable against post-epi thermal processing steps, typically applied before wafer-to-wafer bonding and Si-substrate and Si0.75Ge0.25 backside removal.
Strain relaxed Si 1Àx Ge x buffer layers on Si(001) can be used as virtual substrates for the growth of both strained Si and strained SiGe, which are suitable materials for sub-7 nm CMOS devices due to their enhanced carrier mobility. For industrial applications, the threading dislocation density (TDD) has to be as low as possible. However, a reduction of the TDD is limited by the balance between dislocation glide and nucleation as well as dislocation blocking. The relaxation mechanism of low strain Si 0:98 Ge 0:02 layers on commercial substrates is compared to substrates with a predeposited SiGe backside layer, which provides threading dislocations at the edge of the wafer. It is shown that by the exploitation of this reservoir, the critical thickness for plastic relaxation is reduced and the formation of misfit dislocation bundles can be prevented. Instead, upon reaching the critical thickness, these preexisting dislocations simultaneously glide unhindered from the edge of the wafer toward the center. The resulting dislocation network is free of thick dislocation bundles that cause pileups, and the TDD can be reduced by one order of magnitude.
Most commercial high-temperature superconducting coated conductors based on ion beam assisted MgO deposited templates use LaMnO3 (LMO) films as the terminating buffer layer. In contrast, coated conductors based on inclined substrate deposition (ISD)-MgO technology are still produced with homoepitaxial (homoepi)-MgO as the cap layer. In this work we report on the deposition of LMO buffer layers on ISD-MgO/homoepi-MgO by electron beam physical vapor deposition. The growth parameters of textured LMO films were studied systematically and their properties were optimized regarding the critical current density (J c) of the subsequently deposited DyBa2Cu3O7−δ (DyBCO) superconducting films. LMO films without outgrowths at the surface were obtained at growth rates of up to 4 Å s−1. Despite the formation of non-stoichiometric LMO films containing 59% La, single-phase films were obtained at substrate temperatures below 775 °C and at oxygen partial pressures of up to 4 × 10−4 mbar due to a large homogeneity region towards La. The J c values of DyBCO films deposited on LMO were found to be independent of the LMO thickness in a range from 50 nm to 450 nm. DyBCO films on LMO reach J c = 0.83 MA cm−2 at 77 K in zero applied field. This value is up to 30% higher than those of DyBCO films grown directly on homoepi-MgO. The wide range of LMO growth parameters and higher J c values of DyBCO on LMO compared to DyBCO on homoepi-MgO make this material attractive for its use in manufacturing coated conductors based on ISD-MgO technology.
The misfit dislocation formation related to plastic strain relaxation in Si or Ge quantum well layers in SiGe heterostructures for spin qubits tends to negatively affect the qubit behaviors. Therefore, it is essential to understand and then suppress the misfit dislocation formation in the quantum well layers in order to achieve high-performance qubits. In this work, we studied the misfit dislocation propagation kinetics and interactions by annealing the strained Si or Ge layers grown by molecular beam epitaxy. The annealing temperatures are from 500 to 600 °C for Si layers and from 300 to 400 °C for Ge layers. The misfit dislocations were investigated by electron channeling contrast imaging. Our results show that the misfit dislocation propagation is a thermally activated process. Alongside, the blocking and unblocking interactions during misfit dislocations were also observed. The blocking interactions will reduce the strain relaxation according to theoretical calculation. These observations imply that it is possible to suppress the misfit dislocation formation kinetically by reducing the temperatures during the SiGe heterostructure epitaxy and post-epitaxy processes for developing well-functional SiGe-based spin qubits.
We describe challenges of the epitaxial Si-cap / Si0.75Ge0.25 // Si-substrate growth process, in view of its application in 3D device integration schemes using Si0.75Ge0.25 as backside etch stop layer with a focus on high throughput epi processing without compromising material quality. While fully strained Si0.75Ge0.25 with a thickness >10 times larger than the theoretical thickness for layer relaxation can be grown, it is challenging to completely avoid misfit dislocations at the wafer edge during Si-capping, even for thinner Si0.75Ge0.25 layers. Extremely sensitive characterization methods are mandatory to detect the extremely low density of misfit dislocations at the wafer edge. Light scattering measurements are most reliable. The epitaxial Si-cap / Si0.75Ge0.25 // Si-substrate layer stacks are stable against post-epi thermal processing steps, typically applied before wafer to wafer bonding and Si-substrate and Si0.75Ge0.25 backside removal.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2025 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.