A physics based approach to ultra-shallow p/sup +/-junction formation at the 32 nm node

Abstract

The kinetics of boron electrical activation is studied for both pre-amorphized (PAI) and non-amorphized (non-PAI) samples. It is found that the electrical activation mechanism in both cases is similar and is dominated by a 5eV native point defect driven activation energy barrier, substantially greater than the 3.5eV diffusion activation energy. The physical origins of this mechanism are explained through atomistic simulations and the physical basis of the activation energy difference was used to design a flash anneal capable of achieving highly active and ultra shallow p-type junctions meeting the 32nm node lTRS specifications.

The role of silicon interstitials in the deactivation and reactivation of high concentration boron profiles

“…It has been observed experimentally that preamorphizing implants (PAI) enhances dopant activation during low-temperature SPE regrowth of the amorphous layer, with a minimal amount of dopant diffusion [1,2]. It is generally assumed that B is incorporated into substitutional positions and becomes electrically active, and defects within the amorphous layer are swept towards the surface during the regrowth [3,4].…”

Junction engineering and modeling for advanced CMOS technologies

“…A large fraction of the implant damage is clustered into BICs and then forms immobilized boron in high concentrations at the early stages of the anneal. The activation process happens sequentially by cluster dissolution [8]. There is therefore a tradeoff between TED and activation.…”

“…Due to the BIC behavior, a high anneal temperature and short anneal time are recommended [8]. A spike RTA with a high ramping rate is therefore utilized in order to get the minimum sheet resistance (Rsh) at certain junction depth (Xj).…”

Atomistic Analysis of the Role of Silicon Interstitials in Boron Cluster Dissolution

“…This process produces a large amount of defects in the lattice, which can degrade the device performance. It has been observed experimentally that preamorphizing implants (PAI) enhance dopant activation during low temperature solid-phase-epitaxial (SPE) regrowth of the amorphous layer, with a minimal amount of dopant diffusion [5][6]. Annealing following the implant is used to remove the implant damage, and to electrically activate the dopant atoms.…”

“…Annealing following the implant is used to remove the implant damage, and to electrically activate the dopant atoms. Moreover, in the presence of high B concentrations, subsequent thermal treatments results in additional boron deactivation [6][7][8]. Non-amorphizing implants produce a highly damaged region overlapping with the B profile, causing B clustering [3,4].…”