1. Introduction

Microelectronics is in a perpetual quest for miniaturization, with the aim of improving device performance while reducing manufacturing costs. This approach comes up against physical and technological limits when it comes to going below a dimension of a few tenths of a micrometer. Since the 1970s, the race towards miniaturization has been driven by two complementary approaches:

• the top-down route: this involves miniaturizing devices down to the nanometric scale. The aim of this miniaturization is to increase circuit integration density, which could reach up to 10 ¹² transistors per chip