Holographic method for generating three dimensional conformal photo lithographic masks

• US 5,705,298 A
• Filed: 03/27/1996
• Issued: 01/06/1998
• Est. Priority Date: 12/23/1994
• Status: Expired due to Term

• Current Assignee: Bell Semiconductor, LLC (Hilco Inc. (d/b/a Hilco Global))
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Knoedl, George Jr.
• Primary Examiner(s): ANGEBRANNDT, MARTIN J
• Application Number:
  US08/622,797
• Time in Patent Office: 650 Days
• Field of Search: 430/1, 430/2, 430/5, 430/320, 430/325, 359/1, 359/15, 359/25, 359/35
• US Class Current: 430/2
• CPC Class Codes: G03F 1/50 Mask blanks not covered by G03F1/20 - G03F1/34; Preparation thereof
• CPC Class Codes: G03F 7/001 Phase modulating patterns, e.g. refractive index patterns
• CPC Class Codes: G03H 1/00 Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
• CPC Class Codes: G03H 1/16 using Fourier transform G03H1/10, G03H1/12, G03H1/14 take precedence; analogue computers G06G, e.g. G06G7/19
• CPC Class Codes: G03H 1/20 Copying holograms by holographic , i.e. optical means
• CPC Class Codes: G03H 1/22 Processes or apparatus for obtaining an optical image from holograms G03H1/26 - G03H1/34 take precedence
• CPC Class Codes: H05K 1/0284 Details of three-dimensional rigid printed circuit boards H05K1/119 takes precedence; shaping of the substrate H05K3/0014
• CPC Class Codes: H05K 2203/056 Using an artwork, i.e. a photomask for exposing photosensitive layers
• CPC Class Codes: H05K 3/0002 for manufacturing artworks for printed circuits

Abstract

A three-dimensional photo mask is formed from a substrate having a first side and a three-dimensional side. A holograph is provided on the first side of the substrate. The three-dimensional side of the substrate has a photosensitive resist material provided thereon. The holograph includes information that defines features to be imaged onto the photosensitive resist material. A method and a system are disclosed for producing the three-dimensional mask.

Claims

1. A method of forming a mask, comprising the steps of:

providing a transparent substrate having a first, planar side and an opposing, three-dimensional side, the three-dimensional side conforming to a shape of a workpiece;

providing a hologram at the planar side of said substrate, said hologram is a Fourier or Fresnell transform of a desired three-dimensional lithographic pattern;

providing a photosensitive masking material on the three-dimensional side of the substrate;

placing the substrate having the photosensitive masking material thereon in an index matching liquid;

irradiating light through the first side of the substrate in a pattern according to said hologram to expose the photosensitive masking material to the desired three-dimensional lithographic pattern, the index matched liquid mitigating internal reflections within the substrate; and

removing undesired portions of the photosensitive masking material from the three-dimensional side of the substrate to form said mask having said lithographic pattern.

2. The method of claim 1, wherein said step of providing a hologram at the planar side of said substrate comprises providing said hologram directly on said planar side.

3. The method of claim 1, wherein said step of providing a hologram at the planar side of said substrate comprises providing directly on said planar side, a layer of material containing said hologram.

4. The method of claim 1, wherein said step of providing a hologram comprises providing a mating planar plate bearing said hologram in direct proximity with said planar side.

5. The method of claim 1, further comprising providing a container having optically black walls, said index matching liquid being contained within said container.

6. The method of claim 1, wherein said index matching liquid contains a light absorbing material.

7. A method of forming a mask, comprising the steps of:

providing a transparent substrate having a planar side and an opposing three-dimensional side, the three-dimensional side conforming to a shape of a workpiece;

providing a hologram at the planar side of said substrate, said hologram is a Fourier or Fresnell transform of a desired three-dimensional lithographic pattern;

providing a photosensitive masking material on the three-dimensional side of the substrate;

irradiating light through the planar side of the substrate in a pattern according to said hologram to expose the photosensitive masking material to the desired three-dimensional lithographic pattern; and

removing undesired portions of the photosensitive masking material from the three-dimensional side of the substrate to form said mask having said lithographic pattern.

8. The method of claim 7, wherein said step of providing a hologram at the planar side of said substrate comprises providing said hologram on said planar side.

9. The method of claim 7, wherein said step of providing a hologram at the planar side of said substrate comprises providing directly on said planar side, a layer of material containing said hologram.

10. The method of claim 7, wherein said step of providing a hologram comprises providing a mating planar plate bearing said hologram in direct proximity with said planar side.