Forksheet FETs with Bottom Dielectric Isolation, Self-Aligned Gate Cut, and Isolation between Adjacent Source-Drain Structures
Hans Mertens, R. Ritzenthaler, Yusuke Oniki, P. Puttarame Gowda, G. Mannaert, Farid Sebaai, Andriy Hikavyy, Erik Rosseel, Emmanuel Dupuy, A. Peter, K. Vandersmissen, D. Radisic, B. Briggs, Dmitry Batuk, J. Geypen, G. Martinez-Alanis, F. C. Seidel, Olivier Richard, Boon Teik Chan, Jérôme Mitard, E. Dentoni Litta, Naoto Horiguchi
Abstract
We report on forksheet field-effect transistors that are isolated from the substrate by bottom dielectric isolation (BDI) formed by replacing a SiGe epitaxial layer with a dielectric film while the devices are anchored to the substrate by forksheet walls. Functional unipolar forksheet devices with BDI are demonstrated for both N- and PMOS, for wall widths down to 10 nm. In addition, we describe a scheme to isolate adjacent source-drain structures by the forksheet dielectric wall. This scheme relies on increasing wall height, by means of active area patterning hard mask engineering, to compensate for wall losses in downstream process modules. Finally, self-alignment of gate cut to active is demonstrated morphologically.