Liquid injection ALD of Cp- based precursors for deposition of dielectric materials

The rapid growth of the silicon-based microelectronics industry since the late 1980's has fuelled a demand for greater integrated circuit functionality and improved performance at lower cost. This requires an increased circuit density, which has been achieved by a continual reduction, or scaling , in the dimensions of the field effect transistor (FET). Previously amorphous SiO2 and more recently variants of Si-O-N have been exploited in metal-oxide-semiconductor field effect transistor (MOSFET) technology, due to the stable high quality Si-SiO2 interface achievable, and excellent electrical isolation properties. Shrinking of the transistor feature size in each new 'generation' of devices, has forced the gate dielectric thickness to be reduced, to the nanometre-scale level where direct electron tunnelling effects and high leakage currents present serious obstacles to future device reliability. These 'generations' are commonly described by 'nodes' determined by the half pitch between two CMOS gate contact or first metal level. While 90nm node technologies are in industrial production, 65nm node technologies are in advanced status of industrial development and expected to enter in full production in 2007 at the latest. To move to the 45nm node and beyond, the use of materials with a higher dielectric constant (k) (cf. SiO2 derivatives) allows an equivalent capacitance to be achieved in a physically thicker insulating layer, providing reduced leakage currents. This is a multidisciplinary project with the ultimate objective of developing novel liquid injection atomic layer deposition (ALD) process technologies for the manufacture of next generation gate dielectric thin films. The principal aims of the project are therefore to develop an ALD process based on volatile cyclopentadienyl precursors for deposition of hafnium and rare-earth metal oxides, and to assess the physico-chemical and electronic properties of the resulting high-? dielectric films for semiconductor applications.