N-Channel MOSFETs With Embedded Silicon–Carbon Source/Drain Stressors Formed Using Cluster-Carbon Implant and Excimer-Laser-Induced Solid Phase Epitaxy

In this letter, we report the use of a novel cluster-carbon (C₇ H₇ ⁺) implant and pulsed-excimer-laser-induced solid-phase-epitaxy technique to form embedded silicon-carbon (Si:C) source/drain (S/D) stressors. A substitutional carbon concentration C_sub of ~ 1.1% was obtained in this letter. N-channel MOSFETs (n-FETs) integrated with embedded silicon-carbon (Si:C) S/D stressors formed using the novel cluster-carbon implant and pulsed-laser-anneal technique demonstrate improvement in current drive of 14% over control n-FETs formed with Si preamorphization implant. I_OFFI_DSAT comparison shows a 15% I_DSAT enhancement for n-FETs with embedded Si:C S/D at an I_OFF = 1 nA/mum despite a slightly higher series resistance.

I. Introduction

Mobility-Enhancement techniques are needed to sustain continued improvement in CMOS performance. Silicon–carbon (Si:C) source/drain (S/D) stressors have been demonstrated to induce tensile strain in n-channel MOSFETs (n-FETs) for electron-mobility and drive-current ( or ) enhancement [1]–[9]. While it is straightforward to integrate embedded Si:C S/D in bulk [2], [3] and silicon-on-insulator [4], [8] transistors using an S/D recess etch and selective epitaxy process, integration of S/D stressors is generally more challenging in ultrathin-body [5] or multiple-gate [6], [7] device architectures due to lack of physical margin for S/D recess etch. An attractive and simple approach to form Si:C S/D using implantation of carbon ions and solid phase epitaxy (SPE) was recently demonstrated [9], which also has potential for adoption in advanced device architectures. As compared to implant, implantation of cluster-carbon or cluster-C or ClusterCarbon can achieve higher throughput. There are however no reports on use of molecular- or cluster-C implant for forming Si:C S/D in devices, although Si:C has been successfully formed with cluster-C implant and anneal [10], [11]. Laser anneal on cluster-carbon-implanted S/D has also not been explored.