Process for producing air gaps in microstructures, especially of the air gap interconnect structure type for integrated circuits
AssigneeCommissariat a l'Energie Atomique
InventorAziz Zenasni
Life of this patent
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Abstract
A process for producing at least one air gap in a microstructure, including supplying a microstructure having at least one gap filled with a sacrificial material that decomposes starting from a temperature θ1, this gap being delimited over at least one part of its surface by a non-porous membrane, composed of a material that forms a matrix and of a pore-forming agent that decomposes at a temperature θ2<θ1 by at least 20° C. and that is dispersed in this matrix, then treating the microstructure at a temperature ≧θ2 but <θ1 in order to selectively decompose the pore-forming agent, then treating the microstructure at a temperature ≧θ1 in order to decompose the sacrificial material.
Claims9
A process for producing a microstructure for integrated circuits, said microstructure comprising first and second levels of interconnects, each said level of interconnects comprising a plurality of metal lines separated from one another by an air gap, the process comprising:
- depositing, onto a substrate, a layer of a first sacrificial material that decomposes starting from a temperature θ1;
- etching the layer of the first sacrificial material in accordance with a pattern corresponding to an arrangement to be presented by the metal lines in the first level of interconnects;
- forming metal lines in etched zones of the layer of the first sacrificial material;
- depositing, onto the metal lines thus formed and onto the unetched parts of the layer of the first sacrificial material, a first non-porous membrane composed of a material that forms a matrix and of a pore-forming agent that decomposes at a temperature θ2 at least 20° C. below θ1 and that is dispersed in said matrix;
- depositing, onto the first non-porous membrane, a layer of a second sacrificial material that decomposes starting from a temperature θ3 at least 20° C. below θ2;
- etching the layer of the second sacrificial material in accordance with a pattern corresponding to the arrangement to be presented by the metal lines in the second level of interconnects;
- forming metal lines in the etched zones of the second sacrificial material;
- depositing, onto the metal lines thus formed and onto the unetched parts of the layer of the second sacrificial material, a second non-porous membrane composed of a material that forms a matrix and of a pore-forming agent that decomposes starting from a temperature θ4 at least 20° C. below θ3 and that is dispersed in said matrix;
- heating the microstructure at a temperature at least equal to θ4 but below θ3 to selectively decompose the pore-forming agent present in the second non-porous membrane, to render the second membrane porous;
- heating the microstructure at a temperature at least equal to θ3 but below θ2 to selectively decompose the second sacrificial material;
- heating the microstructure at a temperature at least equal to θ2 but below θ1 to selectively decompose the pore-forming agent present in the first non-porous membrane, to render the first membrane porous;
- and
- heating of the microstructure at a temperature at least equal to θ1 to decompose the first sacrificial material.
Dependencies are inferred from the claim text.