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The segregation of Arsenic and Boron in the interface of a polysilicon on silicon during rapid thermal annealing

Abdelali Merabet 

University de Setif, Faculte des Sciences de l'Ingenieur, Laboratoire Physique et Mecanique des Materiaues, Sétif 19000, Algeria


In this work, we have used wafers achieved in the CNET CNS of Meylan, according to a manufacturing process used for the bipolar compatible technologie CMOS ( Complementary Metal-Oxide-Semiconductor). These wafers of type P, doped with boron. Before the deposit of polysilicon, the oxide film has been removed with HF, followed with a cleanning permits to minimize effects of diffusion barrier in the interface and to increase the gain. Afterwards, the polysilicon recevies either a single implantation with arsenic or boron, or double implantation starting with arsenic and followed by boron. The arsenic play the role of a doping emitter, the boron that the extrinsic base. The samples were then annealed at various temperature between 1000 and 1150oC, for 20 s, to permit an electrical activation of the ions and their fast redistribution. The samples are then analysed by a secondary ion mass spectroscopy (SIMS) CAMECA IMS4F of Lyon, France.
The test of values permits to note that the percentage of the dose distributed in the monosilicium is weaker than the one of the dose segreated in the interface. A remarkable point is the discontinuity of the profiles of diffusion of the boron. This indicates the absence of the segregation peak in the interface. We notice the continuity of arsenic profils extrapolated in the interface, that shows the absence of the barrier of diffusion. It appears that about 11% and 10% of arsenic atoms implanted are segreated in the interface in the ca se of the diffusion and the codiffusion respectively.
The comparison of diffused arsenic dose in the monosilicium in the case of the diffusion and the one of the codiffusion, shows a reduction of about 50% of the arsenic dose in codiffusion relatively to the one in monodiffusion. Where as for the boron, the difference is big which confirms the stopping of the diffusion of the boron in the presence of the arsenic.


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Presentation: poster at E-MRS Fall Meeting 2003, Symposium B, by Merabet abdelali
See On-line Journal of E-MRS Fall Meeting 2003

Submitted: 2003-05-12 20:48
Revised:   2009-06-08 12:55