Characterization of ultra shallow p sup + -n junctions formed by a modified low-energy ion implanter and rapid thermal annealing
The formation of shallow junctions becomes increasingly important as device dimensions are scaled down. Most existing ion implanters are not capable of implanting at energies low enough for the formation of p{sup +}-n junctions shallower than 0.1{mu}m. A conventional ion implanter has been modified for the purpose of implanting at ultra low energies (0.5-5 keV). A deceleration lens was designed using an ion optics simulation program, and less than a 2{degree} variation in incident angles and less than a 50 eV variation in ion energies were achieved for 1 keV B implantation. Ultra shallow p{sup +}-n junctions, 50 nm-110 nm, were formed using the modified low energy ion implanter and rapid thermal annealing. Ge was employed as a preamorphizing ion specie to reduce boron channeling. Defect annihilation behavior for B, BF{sub 2}, Ge + B, and Ge + BF{sub 2} implanted silicon is discussed with respect to RTA annealing temperature. Ge and/or F implantation retard the defect elimination process. SIMS was used to measure boron profiles in Ge preamorphized and non-preamorphized silicon substrates. Diffusion behavior of boron ions was discussed in terms of residual defects. Hall measurements on samples with different Ge energies investigated the dependence of boron activation on the thickness of the amorphous layer. Boron reverse annealing occurred and a mechanism which accounts for this is proposed. Leakage current, measured on the gated diodes fabricated using the four conditions is dependent on the RTA annealing temperature due to defect annihilation. Ge and/or F implantation degrades the electrical junction quality. Device parameters of PMOSFETs fabricated with the four conditions for source/drain junctions are presented. Formation of excellent quality, extremely shallow p{sup +}-n junctions for submicron devices can be achieved using a modified low energy ion implanter and an optimized implantation scheme.
- Research Organization:
- North Carolina State Univ., Raleigh, NC (USA)
- OSTI ID:
- 6904539
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
P-N JUNCTIONS
FABRICATION
ANNEALING
BORON IONS
GERMANIUM IONS
ION IMPLANTATION
TEMPERATURE EFFECTS
CHARGED PARTICLES
HEAT TREATMENTS
IONS
JUNCTIONS
SEMICONDUCTOR JUNCTIONS
360206* - Ceramics
Cermets
& Refractories- Radiation Effects
360201 - Ceramics
Cermets
& Refractories- Preparation & Fabrication