Controlled Thin Oxidation and Nitridation in a Single Wafer Cluster Tool

Abstract

abstractFor both advanced MOS technologies (gate length ≤ 0.25.μm) and EEPROMs, the quality and reproducibility of thin dielectric films (≤ 6 nm) are essential. To obtain such dielectrics involves very precise control of the silicon surface preparation and gate oxide growth. Furthermore, research into such supplementary properties of oxide as improved SiO2/Si interface resistance to current injections or enhanced p+gate resistance to boron penetration in the channel may require nitridation treatment. Such a sequence of steps can be carried out under controled atmosphere using a cluster tool. This paper presents the preliminary results obtained in a single wafer cluster tool on i) the surface preparation under ozone of a silicon wafer immediately after diluted liquid HF treatment and ii) the nitridation of the 6 nm gate oxide under low temperature, low pressure gaseous NO. It is shown that the NO molecule can be successfully used in Rapid Thermal Processing (RTP) and allows gate oxides to be nitrided with properties at least equivalent to those obtained under N2O nitridation, but with a strikingly reduced thermal budget.