No abstract

Supersaturated and metastable silicon-carbon (Si:C) source/drain (S/D) stressors produced by laser anneal allow strain engineering for device performance enhancement. We report the use of a cluster-carbon (normalC7normalH7+) implant and pulsed excimer laser-induced epitaxial crystallization technique to form embedded Si:C S/D stressors with substitutional carbon concentration Csub of ∼1.1% . Transmission electron microscopy, secondary-ion mass spectrometry, and high resolution X-ray diffraction is used to characterize the structure and composition. n-field effect transistors (FETs) integrated with embedded Si:C S/D stressors formed using the normalC7normalH7+ implant and pulsed laser anneal technique demonstrate improvement in Ioff-IDSAT performance of ∼16% over control n-FETs formed without carbon implant at an Ioff=1×10−7A∕μm . Cluster–Carbon implant and laser anneal presented in this work is a simple and cost-effective approach to boost IDSAT performance and is a promising option for strain-engineering in advanced technology nodes.

The reduction of excess-silicon related defects in SIMOX by the supplemental implantation of oxygen has been examined. The supplemental implant is 6% of the oxygen dose used to form the buried oxide, and is followed by a 1000°C anneal, in contrast to the >130O0C anneal used to form the buried oxide layer of SIMOX. The defects examined include shallow electron traps, deep hole traps, and silicon clusters. The radiation-induced shallow electron and deep hole trapping are measured by cryogenic detrapping and isothermal annealing techniques. The low-field (3 to 6 MV/cm) electron tunneling is interpreted as due to a two phase mixture of stoichiometric SiO, and Si clusters a few nm in size. Single and triple SIMOX samples have been examined. All of the defects are reduced by the supplemental oxygen processing. Shallow electron trapping is reduced by an order of magnitude. Because of the larger capture cross section for hole trapping, hole trapping is not reduced as much. The low-field electron tunneling due to Si clusters is also significantly reduced. Both uniform and nonuniform electron tunneling have been observed in SIMOX samples without supplemental processing. In samples exhibiting only uniform tunneling, electron capture at holes has been observed. The nonuniform tunneling is superimposed upon the uniform tunneling and is characterized by current spiking.

In order to form an ultrashallow p+∕n junction, incorporation of a top amorphous-silicon (a-Si) layer is necessary so as to avoid channeling and to fully activate the dopant. Conventional ultrashallow junction processes require two-step implantation such as preamorphization by Si+ or Ge+ implantation and ultralow (<0.5keV) energy B+ implantation. In this report, the authors investigate B18H22+ implantation. Due to the heavy mass of cluster ions, one-step ion implantation at 5keV readily forms a 5-nm-thick a-Si layer and an ultrashallow junction without B channeling. By employing excimer laser annealing, the authors have obtained a shallow junction depth (∼9nm) and low Rs (∼830Ω∕◻).

The radiation response characteristics of single-and multiple-implant SIMOX (separation by implantation of oxygen) buried oxide layers that had received a supplemental oxygen implant and anneal step were measured as a function of temperature and time after exposure to short radiation pulses. A fast capacitance-voltage technique was used for these measurements. The results indicate that, in comparison to standard SIMOX, the supplemental-implant SIMOX buried oxide shows hole motion through the oxide, greatly reduced bulk hole trapping, and little or no bulk shallow electron trapping. Substantial interfacial hole trapping was observed in these materials, as well as deep electron trapping in the single-implant material.