Prevents deterioration of the element characteristics of the gate voltage tolerance and the like which is caused by the metallic contaminants that are sealed in the element forming region at the time of applying a trench separator in a SOI substrate. Polysilicon 12 is formed on the side walls of the trench 5, and the metallic contaminants within the element forming region are collected in this polysilicon 12.
A transistor apparatus includes a silicon substrate and a barrier structure extending substantially from generally adjacent the silicon substrate to a locus displaced from the silicon substrate. The barrier structure generally surrounds a volume containing connection loci for the transistor apparatus and a buried layer in a silicon medium. The connection loci and the buried layer occupy a space generally presenting a first lateral expanse generally parallel with the silicon substrate. The volume presents a second lateral expanse generally parallel with the silicon substrate. The second lateral expanse is greater than the first lateral expanse within a predetermined distance of the substrate.
A method for forming a component in a portion of a semiconductor substrate on insulator delimited by a lateral wall separated by an insulating layer from a peripheral region internal to the portion and heavily doped of a same first conductivity type as the substrate. A conductive plate is formed at the same time as the wall, on a layer of protection of the substrate surface, in electric contact with the peripheral region, the plate extending above said peripheral region towards the inside of the portion with respect to the wall, beyond the location above the limit between the peripheral region and the substrate.
