Experimental study of the boron redistribution in bilayer films silicon-based by SIMS technique
The present work focuses on the study two sets of films bilayers obtained by Low Pressure Chemical Vapor Deposition (LPCVD), for use as material to MOS gate structures (transistors, chemical sensor ISFET, etc.). The first series of films are composed by two layers, silicon amorphous un-doped layer (poly1) and polysilicon boron doped in situ (poly2). The second series are constituted by boron doped polysilicon (polySi) and nitrogen doped polysilicon (NIDOS). These films (poly1/poly2 and polySi/NIDOS) are annealed in tem the same conditions of deposit and annealing. The boron concentration is monitored by secondary ion mass spectrometry (SIMS). The superposition between the SIMS profiles of poly1/poly2 and polySi/NIDOS films have shown that low thermal annealing budget at 600°C/2h, ensures long boron redistribution to the interface poly2/SiO2. At the contrary, a high thermal budget the second layer (poly2) was recristallyzed and reached to the doped oxide. For polySi/NIDOS films, SIMS profiles confirmed the presence of low nitrogen (X = 1%) which can effectively suppress the boron penetration at the interface NIDOS/SiO2.
Reduction of boron penetration through thin silicon oxide with a nitrogen doped silicon layer
Abstract This paper deals with the development of the disilane Si 2 H 6 gaseous source for gate technology and more precisely, reports on the use of nitrogen doped silicon (NIDOS) deposited from disilane and ammonia for the realisation of polycrystalline gate. Boron diffusivity into the NIDOS films is studied thanks to SIMS experiments, and results are extended to the fabrication of P + -poly-Si/NIDOS/SiO 2 /Si capacitive structures. Electrical characterisations evidenced finally the influence of boron and nitrogen atoms on the electrical properties of PMOS devices.
Discontinuity of B‐diffusion profiles at the interface of polycrystalline Si and single crystal Si
Boron diffusion in polycrystalline Si‐on‐single crystal Si systems has been studied by secondary ion mass spectrometry. The extrapolated B‐diffusion profiles in polycrystalline Si and in the single crystal Si substrate reveal a discontinuity at the polycrystalline Si‐single crystal Si interface. The discontinuity in the B profiles is believed to occur due to the blockage of B‐defect complexes by the interfacial oxide between polycrystalline Si and the single‐crystal Si substrate, as well as the immobility of these defect complexes in single crystal Si. The B in the implant peak region above the B solid solubility limit is found to be immobile in single crystal Si during annealing due to the formation of electrically inactive B‐defect complexes. In polycrystalline Si, however, our results show that the B in the peak region spreads out more rapidly than in single crystal Si possibly due to the diffusion of B‐defect complexes along grain boundaries. The B‐defect complexes are electrically inactive as determi...