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Stability of Ultra-Thin Gate Oxides with Boron Doped Polysilicon Gate Structures After Rapid Thermal Annealing

Published online by Cambridge University Press:  21 February 2011

Bojun Zhang ,
Dennis M. Maher ,
Mark S. Denker  and
Mark A. Ray
Bojun Zhang
Affiliation:
Dept. of Materials Science and Engineering, North Carolina State University, Raleigh, NC
Dennis M. Maher
Affiliation:
Dept. of Materials Science and Engineering, North Carolina State University, Raleigh, NC
Mark S. Denker
Affiliation:
Microelectronics Center of North Carolina, Research Triangle Park, NC
Mark A. Ray
Affiliation:
Microelectronics Center of North Carolina, Research Triangle Park, NC
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Abstract

We report a systematic study of dopant diffusion behavior for thin gate oxides and polysilicon implanted gate structures. Boron behavior is emphasized and its behavior is compared to that of As+ and BF2+. Dopant activation is achieved by rapid thermal annealing. Test structures with 100 Å, 60 Å and 30 Å gate oxides and ion implanted polysilicon gate electrodes were fabricated and characterized after annealing by SIMS, SEM, TEM, and C-V rpeasurements. For arsenic implanted structures, no dopant diffusion through a gate oxide of 30 Å thickness and an annealing condition as high as 1 100*C/1Os was observed. For boron implanted structures, as indicated by SIMS depth profiling, structures annealed at 1000*C/10s exhibit a so-called critical condition for boron diffusion through a 30 Å gate oxide. Boron dopant penetration is clearly observed for 60 Å gate oxides at an annealing condition of 1050 0C/10s. The flatband voltage shift can be as high as 0.56 volts as indicated by C-V measurements for boron penetrated gate oxides. However, 100 Å gate oxides are good diffusion barriers for boron at an annealing condition of 1100°C/10s. For BF2 implanted structures, the diffusion behavior is consistent with behavior reported in the literature.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 303: Symposium G – Rapid Thermal and Integrated Processing II , 1993 , 247
Copyright
Copyright © Materials Research Society 1993

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References

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