Hydrogen in silicon: Defect interactions and applications

Hydrogen in crystalline silicon has had a checkered impact on VLSI technology - widely studied, yet its alleged presence or use acknowledged in the barest of terms! Among the well-known phenomena are hydrogen diffusion, dopant deactivation, and bulk and interface defect passivation. More recently, hydrogen plasma treatment has been shown to enhance the rate of formation of thermal donors, as well as activate latent defects under subsequent thermal anneal. It has also been found that disordered and defective regions serve very effectively as sinks and sources for atomic hydrogen. An exciting finding of considerable interest to Si VLSI is the reported improvement in Si MOSFET hot carrier reliability when hydrogen is replaced with deuterium in the post-metallization sintering step. Proposed applications of hydrogen in Si also include lowered thermal budget for ion implant anneal, control of transient enhanced diffusion, impurity gettering, and trapping in gate oxide for a nonvolatile memory device. Here we review hydrogen-related phenomena in crystalline silicon, emphasizing defect interactions and potential applications.