INTEGRATED CIRCUIT COMPRISING AN ISOLATING TRENCH AND CORRESPONDING METHOD
An integrated circuit including at least one isolating trench that delimits an active area made of a monocrystalline semiconductor material, the or each trench including an upper portion including an insulating layer that encapsulates a lower portion of the trench, the lower portion being at least partly buried in the active area and the encapsulation layer including nitrogen or carbon.
1 . Integrated circuit comprising at least one isolating trench that delimits an active area made of a monocrystalline semiconductor material, further comprising at least one MOS transistor gate that is isolated from the active area by a gate insulation layer, upon which is successively deposited:
a layer comprising lanthanum, magnesium, aluminum or dysprosium, said layer being configured to adjust the work function of the gate,
and a metal layer,
to the or each trench comprising an upper portion comprising an insulating layer that encapsulates a lower portion of the trench, the lower portion being at least partly buried in the active area and the encapsulation layer comprising nitrogen or carbon.
2 . Integrated circuit as claimed in claim 1 , wherein the encapsulation layer comprises silicon oxynitride or silicon nitride.
3 . Integrated circuit as claimed in claim 1 , wherein the encapsulation layer comprises silicon oxycarbide or silicon carbide.
4 . Integrated circuit as claimed in claim 1 , wherein the encapsulation layer comprises two protruding elements arranged around the periphery of the layer.
5 . Method for manufacturing an integrated circuit in a monocrystalline semiconductor substrate, said circuit comprising at least one MOS transistor gate, that is isolated from the active area by a gate insulation layer, upon which is successively deposited:
a layer comprising lanthanum, magnesium, aluminum or dysprosium, said layer being configured to adjust the work function of the gate,
and a metal layer,
said method involving the following steps:
forming, in the substrate, at least one lower portion of an isolating trench that delimits an active area; and
forming an insulating encapsulation layer comprising nitrogen or carbon with the insulating layer defining an upper portion of the isolating trench.
6 . Method as claimed in claim 5 which also involves the following successive steps:
forming a gate insulation layer;
forming a layer configured to adjust the work function of the gate; and
forming a layer of conductive material;
7 . Method as claimed in claim 6 which also involves the following step:
forming source and drain areas either side of the gate.
8 . Method as claimed in claims 5 , wherein the insulating encapsulation layer is formed after the following steps:
depositing a layer comprising nitrogen or carbon;
performing photolithography;
partially etching the layer comprising nitrogen or carbon.
9 . Method as claimed in claim 5 , wherein the insulating encapsulation layer is formed after a nitrogen or carbon ion implantation step:
10 . Method as claimed in claim 5 , wherein formation of the insulating encapsulation layer of isolating trench involves the following steps:
forming the encapsulation layer by depositing a compliant layer comprising nitrogen or carbon;
forming an insulating layer by depositing it on the encapsulation layer;
forming etching the insulating layer and the encapsulation layer so that part of the encapsulation layer covers the lower portion of the trench.