Fabrication of 4-inch single-crystalline InP thin film on Si substrate by ion-cutting technique with wafer bonding at elevated temperature

Abstract

The integration of InP thin films onto silicon substrates holds significant promise for optoelectronic device applications. However, achieving large-area, high-quality single-crystal InP films on silicon remains a major challenge. In this work, 4-inch, 200 nm-thick single-crystal InP thin films were successfully transferred onto silicon substrates using ion-cutting of an InP/InGaAs epitaxial structure. To address thermal stress issues during the ion-cutting process for large-area heterogeneous integration wafers, finite element simulations were conducted to analyze thermal stress distributions under different bonding and annealing temperatures. The simulation results revealed abrupt thermal stress concentrations at the edges of the InP/Si bonding pairs, which could be mitigated by bonding at an elevated temperature of 55 °C. The InP/InGaAs epitaxial structure effectively reduced the residual H-ion concentration of the InP film after annealing, with defects localized in the epitaxial InGaAs layer. Following the selective etching of the InGaAs layer, a high-quality 4-inch InP thin film was obtained, exhibiting a surface roughness of 0.347 nm, a full width at half maximum (FWHM) of 212.4 arcsec for the X-ray rocking curve, and a thickness uniformity of 98 %. The large-area InP/Si heterogeneous integration substrate fabricated by ion-cutting with wafer bonding at elevated temperature represents a promising material platform for optoelectronic integration and high-speed electronic applications.