Metal film protection of the surface of a structure formed on a semiconductor substrate during etching of the substrate by a KOH etchant
AssigneeEM Microelectronic
InventorUlrich Münch
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Abstract
The present invention concerns the field of microstructures and in particular microstructures made via CMOS technology on semiconductor substrates intended to undergo micro-machining by wet chemical etching, in particular by a KOH etchant. According to the present invention, protection against the KOH reactive agent is provided to such a structure by the deposition of a metal film (40, 41, 43) including at least on external gold layer (43) on the surface of the structure. This metal film (40, 41, 43) advantageously allows the use of mechanical protective equipment to be omitted and thus allows the wafers to be processed in batches. The present invention also proves perfectly compatible with a standard gold bumping process.
Claims11
A method of manufacturing a structure on a substrate having a first face or front face and a second face or back face, this substrate being formed of a semiconductor base material intended to be etched by the KOH reactive agent, this method including a first step during which at least one zone formed of a material capable of being etched by said KOH reactive agent is formed on said front face, and a second step during which said substrate is etched by said KOH reactive agent,
- wherein, prior to said second step, a metal film including at least one external gold layer is formed on said front face of the structure so as to cover at least said zone and to protect said at least one zone from etching by said KOH reactive agent during said second step.
A method of manufacturing an integrated sensor with a membrane, this integrated sensor being made on a substrate having a first face or front face and a second face or back face, this substrate being formed of a semiconductor base material intended to be etched by the KOH reactive agent, this method including at least:
- a first step consisting in forming a dielectric layer on said front face of the substrate and at least one connection pad on said dielectric layer, this connection pad being formed of a material capable of being etched by said KOH reactive agent;
- a second step consisting in forming at least one electric bump above said connection pad;
- and
- a third step consisting in etching the back face of the substrate by means of said reactive agent in order to form a membrane of said integrated sensor,
- wherein, during said second step, a metal film is formed on said front face so as to cover at least said connection pad, this metal film including at least one external gold layer which is used as a plating base for forming said at least one electric bump during said second step and as protection against etching by said reactive agent during said third step.
Dependencies are inferred from the claim text.