Tuning of Schottky Barrier Height at NiSi/Si Contact by Combining Dual Implantation of Boron and Aluminum and Microwave Annealing.

Feng Sun,Xiangbiao Zhou,Zhi-Jun Qiu,Chaochao Fu,Chen Li,Dongping Wu,Wei Zou,Jun Luo

doi:10.3390/ma11040471

Abstract

Dopant-segregated source/drain contacts in a p-channel Schottky-barrier metal-oxide semiconductor field-effect transistor (SB-MOSFET) require further hole Schottky barrier height (SBH) regulation toward sub-0.1 eV levels to improve their competitiveness with conventional field-effect transistors. Because of the solubility limits of dopants in silicon, the requirements for effective hole SBH reduction with dopant segregation cannot be satisfied using mono-implantation. In this study, we demonstrate a potential solution for further SBH tuning by implementing the dual implantation of boron (B) and aluminum (Al) in combination with microwave annealing (MWA). By using such a method, not only has the lowest hole SBH ever with 0.07 eV in NiSi/n-Si contacts been realized, but also the annealing duration of MWA was sharply reduced to 60 s. Moreover, we investigated the SBH tuning mechanisms of the dual-implanted diodes with microwave annealing, including the dopant segregation, activation effect, and dual-barrier tuning effect of Al. With the selection of appropriate implantation conditions, the dual implantation of B and Al combined with the MWA technique shows promise for the fabrication of future p-channel SB-MOSFETs with a lower thermal budget.

Highlights

Schottky-barrier metal-oxide semiconductor field-effect transistors (SB-MOSFETs) [1], known as metallic source/drain (S/D) MOSFETs (MSD-MOSFETs) [2], have emerged as potential candidates for replacing the conventional p–n junction in an S/D contact
This tendency indicates a positive correlation between the Schottky barrier height (SBH) and microwave power and that more thorough activation and segregation of dopants likely occurs under higher-power microwave radiation
By implementing B and Al dual implantation, we demonstrate a potential solution for further effective φbp reduction to sub-0.1 eV levels and microwave annealing (MWA) absorption enhancement in NiSi/n-Si contacts

Summary

Introduction

Schottky-barrier metal-oxide semiconductor field-effect transistors (SB-MOSFETs) [1], known as metallic source/drain (S/D) MOSFETs (MSD-MOSFETs) [2], have emerged as potential candidates for replacing the conventional p–n junction in an S/D contact. To further improve their performance, the effective Schottky barrier height (SBH) of SB-MOSFETs must be reduced to below 100 meV to overcome problems such as low drive currents and high contact resistance during scaling [4,5,6]. To meet this objective, various metal silicides have been introduced, including nickel silicide because of its low formation temperature and limited Si consumption [7]. Other dopants, such as sulfur [13], selenium [14], and antimony [15], have been employed for effective φbn tuning using various mechanisms

Methods

Results

Conclusion