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US 2004/0175658 A1Published application
Embossing tool having an arbitrary three-dimensional microstructure
OwnerAlfredo M. Morales, Marcela Gonzalesinventors
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Abstract
The present invention describes a method for fabricating an embossing tool or an x-ray mask tool, providing microstructures that smoothly vary in height from point-to-point in etched substrates, i.e., structure which can vary in all three dimensions. The process uses a lithographic technique to transfer an image pattern in the surface of a silicon wafer by exposing and developing the resist and then etching the silicon substrate. Importantly, the photoresist is variably exposed so that when developed some of the resist layer remains. The remaining undeveloped resist acts as an etchant barrier to the reactive plasma used to etch the silicon substrate and therefore provides the ability etch structures of variable depths.
Claims33
A method for fabricating an embossing tool, comprising the steps of:
- providing a silicon substrate;
- forming a first photoresist layer onto a top surface of said substrate;
- exposing a portion of said photoresist layer at a plurality of locations to a collimated image of a source of electromagnetic radiation wherein said step of exposing further includes moving said collimated image across said photoresist layer in a 2-dimensional raster manner at a variable speed thereby providing differing exposure doses to said plurality of individual sites
- developing said first photoresist layer thereby removing said exposed portions of said photoresist layer and exposing a portion of said silicon substrate, said portions of said photoresist layer not exposed to said collimated image remaining intact;
- anisotropically etching said exposed portions of said silicon substrate with a first reactive plasma for a first period of time;
- etching said undeveloped photoresist portions with a second reactive plasma for a second time to remove an incremental part of said undeveloped portion of said photoresist layer, said second reactive plasma exposing additional portions of said silicon substrate;
- repeating said steps of etching until a plurality of etched cavities extending into said substrate thickness are provided, wherein said cavities have one or more surfaces comprising non-prismatic surfaces, and wherein some of said surfaces extend to different depths into said substrate thickness;
- removing remaining portions of said photoresist layer;
- depositing a thin first layer comprising a metal or metals onto said silicon top surface and onto said etched walls and bases;
- depositing a thicker second metal layer over said first layer such that said etched structures are completely filled to form a plurality of metal structures;
- and
- removing said silicon substrate to provide an embossing tool.
9 more elements
An x-ray mask tool, comprising:
- a silicon substrate having a thickness, a top surface, and a bottom surfaces substantially parallel to said top surface, said silicon substrate comprising one or more open cavities etched into said top surface and extending into said substrate thickness, each of said one or more open cavities having one or more surfaces wherein some of said surfaces are non-prismatic surfaces, said surfaces extending to different depths into said substrate thickness, said open cavities filled with a metal deposit to provide a plurality of metal structures embedded into said silicon substrate.
A method for fabricating an x-ray mask tool, comprising the steps of:
- providing a silicon substrate;
- forming a first photoresist layer onto a top surface of said substrate;
- exposing a portion of said photoresist layer at a plurality of locations to a collimated image of a source of electromagnetic radiation wherein said step of exposing further includes moving said collimated image across said photoresist layer in a 2-dimensional raster manner at a variable speed thereby providing differing exposure doses to said plurality of individual sites
- developing said first photoresist layer thereby removing said exposed portions of said photoresist layer and exposing a portion of said silicon substrate, said portions of said photoresist layer not exposed to said collimated image remaining intact;
- anisotropically etching said exposed portions of said silicon substrate with a first reactive plasma for a first period of time;
- etching said undeveloped photoresist portions with a second reactive plasma for a second time to remove an incremental part of said undeveloped portion of said photoresist layer, said second reactive plasma exposing additional portions of said silicon substrate;
- repeating said steps of etching until a plurality of etched cavities extending into said substrate thickness are provided, wherein said cavities have one or more surfaces comprising non-prismatic surfaces, and wherein some of said surfaces extend to different depths into said substrate thickness;
- removing remaining portions of said photoresist layer;
- depositing a thin first layer comprising a metal or metals onto said silicon top surface and onto said etched walls and bases;
- depositing a thicker second metal layer over said first layer such that said etched structures are completely filled;
- and
- planarizing said substrate top surface to remove said metal layers from said top surface to provide an variable dose x-ray mask.
9 more elements
Dependencies are inferred from the claim text.