Demonstration of 300 mm RF-SOI wafers fabricated by layer transfer technology

Abstract

State-of-the-art telecom applications have brought a real challenge to the radio-frequency silicon-on-insulator (RF-SOI) performance. This paper presents the key fabrication technologies for domestic 300 mm RF-SOI wafers fulfilling high-volume manufacture for the first time. To achieve stress relaxation, atmospheric pressure chemical vapor deposition (APCVD) coupled with in situ annealing and chemical mechanical polishing (CMP) was applied to deposit the Poly-Si layer, resulting in a handle wafer with higher resistivity and lower warpage. Furthermore, integration of oxidation thinning and non-contact smoothing is proposed to eliminate the damaged layer caused by the layer transfer, through which surface roughness <3 Å and thickness uniformity <1% can be achieved. Based on power spectral density (PSD) analysis, we investigated the evolution law of different spatial frequency features of the Top-Si surface nano-topography obtained by oxidation thinning and non-contact smoothing. RF performance evaluated via coplanar waveguides (CPW) reveals that substrate loss is below 4 dB cm⁻¹ and a second-order harmonic distortion (HD2) realized −95 dB m at 900 MHz, meeting the requirements for 5G devices. The batch-produced 300 mm RF-SOI has demonstrated excellent repeatability and reproducibility, signifying a breakthrough in domestic 300 mm RF-SOI.