Influence of Arsenic Clustering and Precipitation on the Interstitial and Vacancy Concentration in Silicon
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Influence of Arsenic Clustering and Precipitation on the Interstitial and Vacancy Concentration in Silicon R. Brindosa, M. H. Clarka, K. S. Jonesa, M. Griglioneb, Hans-J. Gossmannb, A. Agarwalc, B. Murtod and E. Andidehe a) SWAMP Center, Department of Materials Science and Engineering, University of Florida, Gainesville, FL 32611-6130 b) Agere Systems, Orlando, FL 32819 c) Eaton Corporation, Beverly, MA 01915 d) International SEMATECH, Austin, TX 78741 e) Intel Corporation, Portland Technology Development, 5200 NE Elam Young Parkway, Hillsboro, OR 97124
ABSTRACT The point defect injection from arsenic precipitation was studied using boron marker layers and antimony doped superlattices. Comparisons of arsenic and germanium amorphizing implants showed similar boron marker layer diffusion enhancements after spike annealing. The results indicate that the end of range damage caused by the implants was the source of the diffusion enhancement. Additional annealing cycles showed that there was retardation in the diffusion enhancement of the boron marker layers for precipitation range arsenic implants. Antimony marker layers showed no diffusion enhancement due to vacancy injection. The results of the experiments indicate that arsenic-interstitial complexes are the cause of the decrease flux of interstitials to the bulk. INTRODUCTION As the semiconductor community continues to decrease the size of the transistor to smaller and smaller dimensions, issues of dopant diffusion and dopant activation become some of the major concerns. Arsenic is generally used as an n-type dopant in silicon due to its high solubility and low diffusivity. Even though arsenic displays these desirable qualities, the increased demands are pushing the limits of its usefulness.1 The regions with arsenic doping are generally at concentrations that exceed the solid solubility limit in silicon. It has been shown in previous studies that exceeding the solubility limit presents many problems in silicon.2-4 Recent studies by Jones et al.5 have shown that at low energies and moderate doses, arsenic displays dramatic transient enhanced diffusion (TED) effects after anneals at 750°C while no evidence of extended defects are found. Since arsenic is known to diffuse by a dual mechanism involving interstitials and vacancies,6 the TED effects were suggested to be due to the formation of mobile arsenic-interstitial complexes or a vacancy release upon monoclinic SiAs precipitate formation.7-9 These explanations are possible due to the different stages of arsenic-defect interactions available as the arsenic concentration is increased. At low arsenic concentrations (< 1x1020cm-3) arsenic has been shown to affect interstitial populations by forming arsenic-interstitial complexes.10,11 As the arsenic concentration is increased, arsenic-vacancy clusters begin to form and eventually a concentration is reached where SiAs precipitates form.12-19 It has been suggested that the formation of SiAs precipitates occurs through the combining of arsenic-vacancy clusters.20 When the c
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