Atomic Scale Thickness Control of SOI Wafers for Fully Depleted Applications

Abstract

Smart Cut® Technology has recently been moved forward to a performance that seemed impossible until just recently. FDSOI requirements demand a method to transfer an ultra-thin crystalline layer with near perfect uniformity. Silicon thickness variation across all UTBOX wafers has reached +/- 5 A all points all wafers, while at the same time roughness has been improved to reach 0.8 A 30x30 µm2 RMS. BOX is available over a wide range of thicknesses from 10 to 50nm, ready to satisfy all possible applications. Such development efforts have now passed process technology qualification [1] and provided a proven path for further node scaling [2]. This paper reports the latest achievements in state of the art thickness and roughness control, which is enabling very low variability for fully depleted devices today.