Method for fabricating bulbous-shaped vias

• US 7,071,088 B2
• Filed: 08/23/2002
• Issued: 07/04/2006
• Est. Priority Date: 08/23/2002
• Status: Expired due to Fees

• Current Assignee: Mii Newco, Inc. (Canon Inc.)
• Original Assignee: Molecular Imprints, Inc. (Canon Inc.)
• Inventors: Sreenivasan, Sidlgata V., Watts, Michael P. C.
• Primary Examiner(s): Lebentritt, Michael S.
• Assistant Examiner(s): Geyer, Scott B.
• Application Number:
  US10/227,105
• Publication Number:
  US 20040038552A1
• Time in Patent Office: 1,411 Days
• Field of Search: 438/597, 438/612, 438/613, 438/665, 438/666, 438/668, 438/669, 438/672, 438/674, 438/675, 264/31, 264/32
• US Class Current: 438/612
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: B82Y 40/00 Manufacture or treatment of nanostructures
• CPC Class Codes: G03F 7/0002 Lithographic processes using patterning methods other than those involving the exposure to radiation, e.g. by stamping
• CPC Class Codes: H01L 21/02118 carbon based polymeric organic or inorganic material, e.g. polyimides, poly cyclobutene or PVC polymers per se C08G, photoresist per se G03F
• CPC Class Codes: H01L 21/0272 for lift-off processes
• CPC Class Codes: H01L 21/28587 characterised by the sectional shape, e.g. T, inverted T
• CPC Class Codes: H01L 21/312 Organic layers, e.g. photoresist H01L21/3105, H01L21/32 take precedence; photoresists per se G03C
• CPC Class Codes: H01L 21/76804 by forming tapered via holes
• CPC Class Codes: H01L 21/76817 using printing or stamping techniques

Abstract

The present invention provides a method for fabricating bulbous-shaped vias on a substrate, having a surface, by disposing, on the substrate, a polymerizable fluid composition. A mold is placed in contact with the polymerizable fluid composition. The mold includes a relief structure on a surface thereof to create a recess in a layer of the polymerizable fluid composition. The polymerizable fluid composition is subjected to conditions to cause polymerization, forming a polymerized layer having a solidified indentation. An opening to the surface of the substrate is formed by removing material disposed on the substrate surface through etch processes. In a further embodiment a conductive layer may be disposed in the opening to form a gate. A lift-off process may be employed to remove the polymerized layer.

Claims

1. A method for fabricating vias on a substrate having a surface, comprising:

disposing, adjacent to said substrate, a polymerizable fluid composition;

contacting said polymerizable fluid composition with a mold having a relief structure, with said polymerizable fluid composition conforming to a profile of said mold;

subjecting said polymerizable fluid composition to conditions to polymerize said polymerizable fluid composition, forming a polymerized layer having a bi-level indentation including a nadir and shoulders spaced-apart from said nadir;

forming a relief pattern adjacent to said substrate having an opening extending toward said surface by selectively removing material adjacent to said substrate, with said material including a sub-section of said polymerized layer located proximate to said bi-level indentation; and

depositing a conductive layer to cover said relief pattern, thereby forming a contact having a shape defined by said relief pattern.

2. The method as recited in claim 1 wherein forming further includes selectively etching said nadir.

3. The method as recited in claim 1 further including disposing a planarization layer on said surfaces to be positioned between said surface and said polymerizable fluid composition, with selectively removing further including etching said bi-level indentation to expose a sub-portion of said surface, with said material further including a portion of said planarization layer.

4. The method as recited in claim 1 further including disposing an etch-stop layer on said surface, and disposing a planarization layer adjacent to said etch-atop layer, with said planarization layer being disposed between said etch-stop layer and said polymerizable fluid composition, said etch-stop layer having positive resist properties, with forming further including etching said bi-level indentation to form said relief pattern in said planarization layer, with said relief pattern matching a contour of said bi-level indentation, selectively etching said relief pattern to expose a sub-portion of said etch-stop layer, subjecting said sub-portion to conditions to change properties associated with said etch-stop layer, and removing said sub-portion to expose a region of said surface in superimposition with said sub-portion, with said material further including said sub-portion.

5. The method as recited in claim 1 further including removing said polymerized layer.

6. The method as recited in claim 1 further including providing said mold with said relief structure, with said relief structure being selected from a set consisting essentially of a projection and a recession.

7. The method as recited in claim 1 wherein said polymerizable fluid composition includes a mono-functional acrylate component, a poly-functional molecule component, and an initiator component combined with said mono-functional acrylate component and said poly-functional molecule component to provide a viscosity no greater than 2 cps to preferentially wet said surface forming a contact angle therewith no greater than 75°

, with said initiator component being responsive to ultra violet radiation to initiate a free radical reaction to cause said mono-functional acrylate component and said poly-functional molecule component to polymerize and cross-link.

8. The method as recited in claim 1 wherein said polymerizable fluid composition includes a combination of a plurality of mono-functional acrylate molecules, a plurality of poly-functional molecules;

and a plurality of initiator molecules, with said combination having a viscosity in a range of 1 to 2 cps, and preferentially wets an organic polymer surface forming a contact angle of less than 75°

, while not dissolving more than 500 nm of said organic polymer surface upon being removed one minute after wetting said organic polymer surface, minimizing wetting of an adjacent silylating containing surface, forming a contact angle therewith that is greater than 75°

, with said plurality of initiator molecules being responsive to a pulse of ultra-violet radiation, containing less than 5 J cm-2, to cause said plurality of mono-functional acrylate molecules and said plurality of poly-functional molecules to polymerize and cross-link, defining a cross-linked polymer layer, said composition providing thermal stability to said cross-linked polymer layer when subjected to an atmosphere of 75°

C. for thirty minutes so that a variation in an angle, measured between a bottom of an indention and a sidewall formed therein, is no more than 10%.

9. A method for fabricating vias on a substrate having a surface, comprising:

disposing an etch-stop layer on said surface;

disposing, adjacent to said etch-stop layer, a polymerizable fluid composition;

contacting said polymerizable fluid composition with a mold with said polymerizable fluid composition conforming to a profile of said mold;

subjecting said polymerizable fluid composition to conditions to polymerize said polymerizable fluid composition, forming a polymerized layer having a solidified indentation including a nadir and shoulders spaced-apart form said nadir, with said etch-stop layer being positioned between said surface and said polymerized layer; and

defining an opening to said surface of said substrate by removing material disposed on said substrate, with said material including a sub-section of said polymerized layer positioned proximate to said solidified indentation and a sub-portion of said etch-stop layer in superimposition with said nadir.

10. The method as recited in claim 9 further including disposing a planarization layer adjacent to said etch-stop layer, with said planarization layer being disposed between said etch-stop layer and said polymerizable fluid composition, with removing further including etching said solidified indentation to expose and form a relief pattern in said planarization layer, with said relief pattern matching a contour of said solidified indentation, and etching said relief pattern to expose said sub-portion of said etch-stop layer, subjecting said sub-portion to conditions to change properties of said sub-portion and facilitate removing of said sub-portion to expose a region of said surface in superimposition with said sub-portion.

11. The method as recited in claim 10 further including depositing a conductive layer to cover said region and said relief pattern to form a contact having a shape defined by said relief pattern, and removing said polymerized layer and said planarization layer.

12. The method as recited in claim 11 wherein said polymerizable fluid composition includes a mono-functional acrylate component, a poly-functional molecule component;

and an initiator component combined with said mono-functional acrylate component and said poly-functional molecule component to provide a viscosity no greater than 2 cps to preferentially wet said surface forming a contact angle therewith no greater than 75°

, with said initiator component being responsive to actinic radiation to initiate a free radical reaction to cause said mono-functional acrylate component and said poly-functional molecule component to polymerize and cross-link.

13. A method for fabricating vias on a substrate having a surface, comprising:

disposing an etch-stop layer on said surface;

disposing a planarization layer onto said etch-stop layer;

disposing, on said planarization layer, a polymerizable fluid composition;

contacting said polymerizable fluid composition with a mold having a relief structure, with said polymerizable fluid composition conforming to a profile of said relief structure;

subjecting said polymerizable fluid composition to conditions to polymerize said polymerizable fluid composition, forming a polymerized layer having a solidified bi-level indentation including a nadir and shoulders spaced-apart from said nadir, with said etch-stop layer being positioned between said surface and said polymerized layer, said etch-stop, planarization and polymerized layers, defining a composite layer;

anisotropically etching said composite layer to form a relief pattern in said planarization layer, with said relief pattern matching a contour of said solidified bi-level indentation and having relief shoulders and a relief nadir, spaced-apart therefrom;

selectively etching said relief pattern to expose a sub-portion of said etch-stop layer in superimposition with said relief nadir; and

removing said sub-portion to expose a region of said surface in superimposition therewith.

14. The method as recited in claim 13 further including removing said planarization layer employing a chemical wet-etch before removing said sub-portion.

15. The method as recited in claim 13 further including depositing a conductive layer to cover said region and said relief pattern to form a contact having a shape defined by said relief pattern.

16. The method as recited in claim 15 further including removing said polymerized layer and said planarization layer.

17. The method as recited in claim 16 further including forming source and drain portions in said substrate, with said region being positioned between said source and drain portions.

18. The method as recited in claim 17 wherein said polymerizable fluid composition includes a mono-functional acrylate component, a poly-functional molecule component;

and an initiator component combined with said mono-functional acrylate component and said poly-functional molecule component to provide a viscosity no greater than 2 cps to preferentially wet said surface forming a contact angle therewith no greater than 75°

, with said initiator component being responsive to actinic radiation to initiate a free radical reaction to cause said mono-functional acrylate component and said poly-functional molecule component to polymerize and to cross-link.

19. A method for fabricating vias on a substrate having a surface, comprising:

disposing, adjacent to said substrate, a planarization layer;

forming, on said planarization layer, a polymerized layer having a bi-level indentation; and

etching said polymerized layer and said planarization layer to expose and form a relief pattern in said planarization layer, with said relief pattern having a curved bulb extending from a region of said planarization layer proximate to said polymerized layer and terminating in a narrow waist.

20. The method as recited in claim 19 wherein forming further includes depositing a polymerizable fluid composition and contacting said polymerizable fluid composition with a mold having a relief structure formed therein and subjecting said polymerizable fluid composition to conditions to polymerize said polymerizable fluid composition, forming said polymerized layer having said bi-level indentation.

21. The method as recited in claim 19 wherein said bi-level indentation further includes a nadir and shoulders spaced-apart from said nadir, with etching further including selectively etching said nadir to remove portions of said polymerized and planarization layers in superimposition with said nadir to expose an area of said substrate.

22. The method as recited in claim 19 further including disposing an etch-stop layer on said substrate, with said etch-stop layer being disposed between said substrate and said planarization layer.

23. The method as recited in claim 22 wherein said bi-level indentation further includes a nadir and shoulders spaced-apart from said nadir, with etching further including selectively etching said nadir to remove portions of said polymerized and planarization layers in superimposition with said nadir to expose an area of said etch-stop layer.

24. The method as recited in claim 19 further including disposing an etch-stop layer on said substrate, with said etch-stop layer being disposed between said substrate and said planarization layer, with said etch-stop layer having positive resist properties.

25. The method as recited in claim 19 further including depositing a conductive layer to cover said bi-level indentation to define a contact having a profile defined by said bi-level indentation.

26. The method as recited in claim 25 further including removing from said substrate, remaining portions of said planarization layer and said polymerized layer.

27. The method as recited in claim 19 wherein disposing further includes spin-coating an aromatic material onto said substrate.

28. The method as recited in claim 19 wherein forming further includes depositing, on said planarization layer, a material including a mono-functional acrylate component, a poly-functional molecule component, and an initiator component combined with said mono-functional acrylate component and said poly-functional molecule component.