Patent ID: 7316951

Claim:
Fabrication method for a trench capacitor having an insulation collar in a silicon substrate, having the steps of: (a) providing a trench in the silicon substrate; (b) providing the insulation collar in the upper trench region as far as the top side of the silicon substrate; (c) depositing a layer made of a metal oxide in the trench, said layer comprising a rare earth oxide; (d) carrying out a thermal treatment for selectively reducing the layer, a region of the layer that lies below the insulation collar above the silicon substrate being reduced and being converted into a first capacitor electrode layer made of a corresponding metal silicide, and a region of the layer that lies above the insulation collar not being reduced; (e) removing selectively the non-reduced region of the layer that lies above the insulation collar; (f) providing a capacitor dielectric layer in the trench above the first capacitor electrode layer; and (g) providing a second capacitor electrode layer in the trench above the capacitor dielectric layer.