Nano-scale depth-varying recrystallization of oblique Ar+ sputtered Si(111) layers

Divya Gupta,G R Umapathy,Sunil Ojha,Sanjeev Aggarwal,Rahul Singhal

doi:10.1038/s41598-020-68873-8

Abstract

Silicon, the workhorse of semiconductor industry, is being exploited for various functional applications in numerous fields of nanotechnology. In this paper, we report the fabrication of depth controllable amorphous silicon (a-Si) layers under 80 keV Ar+ ion sputtering at off-normal ion incidences of 30°, 40° and 50° and crystallization of these amorphous Si(111) layers under thermal annealing. We find that the irradiated samples were not fully amorphized even for the lowest oblique incidence of 30°. Sputtering at off-normal incidences induces depth controllable surface amorphization in Si(111). Annealing at temperature of 1,073 K is characterized by formation of depth-varying buried amorphous layer due to defect recrystallization and damage recovery. Some remnant tensile stress has been observed for recrystallized samples even for lowest oblique incidence. The correlation of amorphization and stress due to sputtering induced by oblique incidence has been discussed systematically. The possible mechanism of recrystallization is discussed in terms of vacancies produced in sputtering dominated regime and their migration during annealing treatment. Our results reveal that with appropriate selection of oblique ion beam sputtering parameters, depth controllable surface amorphization and recrystallization may be fine-tuned to achieve co-existing amorphous and crystalline phases, playing a crucial role in fabrication of substrates for IC industry.

Highlights

Silicon, the workhorse of semiconductor industry, is being exploited for the various applications in numerous fields of nanotechnology like development of FETs and infrared d etectors[1,2,3]
Present research focuses on experimentally investigating the role of sputtering in regrowth of amorphous Si layers produced by oblique argon ion sputtering under thermal annealing
The structural alterations resulting from ion beam induced amorphization and subsequent annealing process was studied as a function of off-normal incidence of argon ions by Raman spectroscopy

Summary

Introduction

The workhorse of semiconductor industry, is being exploited for the various applications in numerous fields of nanotechnology like development of FETs and infrared d etectors[1,2,3]. The structural alterations resulting from ion beam induced amorphization and subsequent annealing process was studied as a function of off-normal incidence of argon ions by Raman spectroscopy. To study in detail the amorphization and recrystallization behavior, we present in Fig. 3 the damage profiles D(z) as a function of penetration depth of incoming ions for different angle of incidences.

Results

Conclusion