US 2003/0215664 A1Published application

Method for providing an arbitrary three-dimensional microstructure in silicon using an anisotropic deep etch

AssigneeSandia National Laboratories

InventorsAlfredo M. Morales, Marcela Gonzales

Life of this patent

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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

Dependent claims

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

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.

Facts

Application: 10/146,421Filed 14 May 2002
Published: 20 Nov 2003
Term ends: Not estimatedThe source records don’t support an estimate.

Classification16 codes

G03F 1/22
Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles…
B29C 33/38
Moulds or cores; Details thereof or accessories therefor: characterised by the material or the manufacturing process
B29C 33/424
Characterised by the shape of the moulding surface, e.g. ribs or grooves: moulding surfaces provided with means for marking or patterning
G03F 1/50
Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles…