Ordered Polymer-Based Spin-On Dopants

摘要

Conventional doping of crystalline Si via ion implantation results in a stochastic distribution of doped regions in the x-yplane along with relatively poor control over penetration depth of dopant atoms. As the gate dimensions get to 10 nm,the related device parameters also need to be scaled down to maintain electrical activity. Thus highly doped abrupt,ultra-shallow junctions are imperative for source-drain contacts to realize sub-10 nm transistors. Uniform ultra-shallowjunctions can be achieved via monolayer doping, wherein thermal diffusion of a self-limiting monolayer of dopant atomcontainingorganic on Si surface yields sub-5 nm junctions. We have extended the use of organic dopant molecules inthe monolayer doping technique to introduce a new class of spin-on polymer dopants. In effect, these new spin-ondopants offer a hybrid between the monolayer doping technique and traditional inorganic spin-on dopants. We have beenable to uniformly introduce p- and n-type dopants with doping efficiencies comparable to the monolayer dopingtechnique. Control over junction depth can be easily achieved via optimizing annealing temperature and time.Concurrently, sequestering the dopant precursors within the cores of block copolymer micelles allows us to achieveprecise control over the spatial positions of dopant atoms in all three dimensions owing to the high periodicity of blockcopolymer domains on the 10-100 nm length scale.