Enhanced Boron Diffusion in Amorphous Silicon
- PDF / 95,158 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 47 Downloads / 264 Views
C10.3.1
Enhanced Boron Diffusion in Amorphous Silicon
J.M. Jacques, N. Burbure, and K.S. Jones Department of Materials Science and Engineering, University of Florida, Gainesville, FL 32611 M.E. Law Department of Electrical and Computer Engineering, University of Florida, Gainesville, FL 32611 L.S. Robertson Texas Instruments Inc., Dallas, TX 75081 D.F. Downey Varian Semiconductor Equipment Associates, Gloucester, MA 01930 L.M. Rubin Axcelis Technologies, Beverly, MA 01915 J. Bennett and M. Beebe International SEMATECH, Austin, TX 78741 M. Klimov AMPAC/MCF, University of Central Florida, Orlando, FL 32826
Abstract In prior works, we demonstrated the phenomenon of fluorine-enhanced boron diffusion within self-amorphized silicon. Present studies address the process dependencies of low temperature boron motion within ion implanted materials utilizing a germanium amorphization. Silicon wafers were preamorphized with either 60 keV or 80 keV Ge+ at a dose of 1x1015 atoms/cm2. Subsequent 500 eV, 1x1015 atoms/cm2 11B+ implants, as well as 6 keV F+ implants with doses ranging from 1x1014 atoms/cm2 to 5x1015 atoms/cm2 were also done. Furnace anneals were conducted at 550oC for 10 minutes under an inert N2 ambient. Secondary Ion Mass Spectroscopy (SIMS) was utilized to characterize the occurrence of boron diffusion within amorphous silicon at room temperature, as well as during the Solid Phase Epitaxial Regrowth (SPER) process. Amorphous layer depths were verified through Cross-Sectional Transmission Electron Microscopy (XTEM) and Variable Angle Spectroscopic Ellipsometry (VASE). Boron motion within as-implanted samples is observed at fluorine concentrations greater than 1x1020 atoms/cm3. The magnitude of the boron motion scales with increasing fluorine dose and concentration. During the initial stages of SPER, boron was observed to diffuse irrespective of the co-implanted fluorine dose. Fluorine enhanced diffusion at room temperature does not appear to follow the same process as the enhanced diffusion observed during the regrowth process.
C10.3.2
Introduction As the semiconductor industry continues to move towards smaller microelectronic devices, the pressure for precise process optimization and the development of novel material combinations becomes more paramount. Over the years, there has been significant interest within the avenue of boron and fluorine co-implantation for the formation of ultra-shallow junctions. Previous studies have detailed the ability of fluorine to reduce boron Transient Enhanced Diffusion (TED) 1-3, as well as to enhance boron diffusion during the Solid Phase Epitaxial Regrowth (SPER) process. 4-5 The majority of studies have utilized silicon selfpreamorphizing conditions. However, the behavior of boron within germanium amorphized material is of great interest, as silicon and germanium Pre-Amorphization Implants (PAI) are often used interchangeably. These studies focus upon the diffusion behaviors of boron at both room temperature and during SPER, in the presence and absence of fluorine, within
Data Loading...
