Optimization of P+/N junction formation using solid phase epitaxy for the 100 nm technology node and beyond

Abstract

P+/N diodes are fabricated using a low energy boron implant followed by solid phase epitaxial (SPE) growth at 600°C. The pre-amorphization step was done using Germanium at either 10 keV or 80 keV, both with a dose of 1 × 1015 ions/cm2. Next, boron was implanted at a range of energies from 0.5 keV to 5 keV. The sheet resistance (Rs) measurements and the secondary ion mass spectrometry (SIMS) analysis from the SPE based diodes showed very good results that meet the Junction depth and the sheet resistance requirements for the 100 nm and 70 nm technology nodes using a 10 keV Ge+ pre-amorphization and sub-keV boron implant. However, these diodes were leaky because of the end of range (EOR) defects positioned within their depletion regions. At higher boron energies (2-5 keV), the remaining EOR defects from the 10 keV germanium pre-amorphization step were positioned closer to the surface and farther from the depletion region. These diodes showed lower leakage current densities by two orders of magnitude and a breakdown voltage greater than -4 V. This highlights the strong relationship between the SPE diode characteristics and the remaining EOR position with regards to the depletion region.