| 摘要 |
The invention describes a method for forming spacers (152a, 152b) of a field effect transistor gate, comprising a step of forming a protection layer (152) covering the gate of said transistor, at least a step of modifying the protection layer, executed after the step of forming the protection layer, by contacting the protection layer (152) with plasma comprising ions heavier than hydrogen and CxHy where x is the proportion of carbon and y is the proportion of hydrogen to form a modified protection layer (158) and a carbon film (271). The protection layer being nitride (N)-based and/or silicon (Si)-based and/or carbon (C)-based and shows a dielectric constant equal or less than 8. |
| 主权项 |
1. A method for forming spacers of a field effect transistor gate, with the gate comprising a top and flanks and being located above an active layer made of a semiconductor material, characterized in that it comprises:
at least a step of forming a protection layer covering the gate, the protection layer being a layer based on nitride (N) and/or based on silicon (Si) and/or based on carbon (C) with a dielectric constant equal to or less than 8; at least a step of modifying the protection layer by contacting the protection layer with a plasma wherein CxHy is introduced, where x is the proportion of carbon (C) and y is the proportion of hydrogen ions (H), and comprising ions heavier than hydrogen; with the conditions of plasma, more particularly the concentration of CxHy, the energy of ions of the plasma and the main implantation direction being so chosen that:
plasma creates an anisotropic bombardment with hydrogen-based ions (H, H+, H2+, H3+ etc.), resulting from the CxHy, with the bombardment being anisotropic in the main implantation direction which is parallel to the flanks of the gate so as to form a modified protection layer by modifying portions of the protection layer located on the top of the gate and both sides of the gate and so as to keep non-modified portions of the protection layer covering the flanks of the gate.carbon-containing plasma chemical species from the CxHy, form a carbon-containing film in particular on surfaces parallel to the main direction of implantation;the plasma creates a bombardment with ions heavier than hydrogen which prevents said carbon-containing plasma chemical species from the CxHy from forming a carbon-containing film, more particularly on the surfaces of the protection layer which are perpendicular to the main direction. at least a step of removing the modified protection layer using a selective etching of the modified protection layer relative to non-modified portions of the protection layer. |
