Effect of oxidation treatments on the redistribution of the boron in the thin films of polycrystalline silicon Si-LPCVD used in VLSI

Département d'Électronique, Faculté des Sciences de l'Ingénieur, Université de Constantine, Route d'Ain El-Bey, 25000 Constantine, Algeria

Corresponding author: a_kaki@caramail.com

Received: 23 August 2002
Revised: 25 March 2003
Accepted: 30 October 2003
Published online: 19 January 2004

Abstract

Results of a quantitative characterisation SIMS at high levels of boron-doping concentration (2 × 10²⁰ cm⁻³) of in situ boron-doped LPCVD-polysilicon thin films before and after thermal-oxidation treatments are presented. Measurements of the precedent characterisation methods (SIMS) are performed on submicron layers (300 nm) deposited at the extreme temperatures T_d = 520 °C and T_d = 605 °C. The thermal-oxidation experiments are carried out under dry oxygen (O₂) at three oxidation temperatures T_ox = 840 °C, 945 °C and 1050 °C for several durations. After these thermal-oxidation processes, remarkable changes in the behavior of doping profile are observed. This behavior seems to be typically characteristic of the in situ heavily boron-doped films. In addition to the presence of some saturation-thermal-dependence phenomenon, we find that these results well correlate and support the presence of another phenomenon called “Differential of the Oxidation Rate (DOR)” which is evidenced as typical of the in situ doped films.