Introduction

Abstract

Introduced in mass production at the beginning of the 1970s, the Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET) is the key element of modern integrated circuits. Although the transistor feature size has shrunk dramatically over the past three decades, its overall design stayed nearly the same until recently. Even the 90 nm technology node MOSFETs introduced in 2004–2005 and still found in nowadays computers are based on the same principle and consist of the same basic elements as three decades ago. The inversion channel, which connects the source and drain electrodes, is formed at the silicon interface by applying a certain voltage to the gate electrode. The gate electrode made of heavily doped poly-silicon is electrically separated from the inversion channel by an oxide layer. A high quality silicon dioxide is resilient against an electrical break-through even at high electric fields and possesses little defects at the Si/SiO₂ interface. The good quality of this interface guarantees high mobility of the carriers in the inversion channel. Due to their perfect compatibility, the pair Si/SiO2 has quickly become the main stream microelectronic element of Si-based MOSFETs. Low defect density, high yield, and a relatively simple and inexpensive fabrication process have put MOSFETs into the heart of all modern high density integrated circuits.