Hiroshi Satani

Hydrogen Implantation Damage in Polycrystalline Silicon Thin Film Transistors Caused by Ion Doping

The effect of hydrogen implantation into the channel region by ion doping on the characteristics of p-channel polycrystalline silicon (poly-Si) thin film transistors (TFTs) was investigated. To study the hydrogen ion damage in detail, two sets of ion doping conditions, which have different hydrogen profiles with the same boron dose, were adopted to make the source and drain regions of TFTs. Although the boron concentration in both sets of doping conditions is the same, a large difference in the Id–Vg characteristics was observed between the two TFTs. Field effect mobility and threshold voltage deteriorated as the hydrogen dose increased during ion doping. The H2+ ions implanted into the channel region are the dominant influence on the TFT performance. From electron spin resonance (ESR) measurement, the spin density of channel poly-Si was found to increase after ion doping. The hydrogen ions cause defects in the channel region and deteriorate TFT characteristics such as mobility and subthreshold characteristics.