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.
Boron doped polysilicon deposition in a sector reactor : Specific phenomena and properties
In this paper, the advantages of a new LPCVD reactor, called sector reactor, are presented. This reactor is a small scale pilot plant of an annular reactor, designed to solve the problem of uniformity of thickness observed in tubular reactors. This work describes the deposition of in situ Boron doped Silicon from BCl 3 and SiH 4 . The kinetic results shows that the use of the sector reactor allows deposition at temperature as low as 450°C, pressure as high as 6Torr, deposition rates as high as 80nm/mn, keeping the homogeneity of thickness and resistivity at a good level on 10cm substrates. The kinetic and resistivity results are compared to what is obtained in conventional furnace, and are interpreted in terms of gas phase reactions. Finally, the advantage of processing at low temperature ( 0.5μm).
Properties of nitrogen doped silicon films deposited by low pressure chemical vapour deposition from disilane and ammonia
Abstract Nitrogen doped silicon films have been deposited by low pressure chemical vapour deposition from disilane Si 2 H 6 and ammonia NH 3 . Deposition kinetics is investigated, pointing out the influences of the deposition temperature, the total pressure and the gas flow rates. According to the Bruggeman theory, variations of the NH 3 /Si 2 H 6 gaseous ratio allow for a wide range of the SiN x stoichiometry as well as a good control of the film nitrogen doping. The different behaviours of the nitrogen atom in silicon films are discussed and an overview of the nitrogen doped silicon physical properties (optical, mechanical and electrical) is proposed for the development of boron-doped polysilicon gates.