Method for fabricating thin film metallic meshes for use as Fabry-Perot interferometer elements, filters and other devices

• US 4,818,661 A
• Filed: 07/21/1987
• Issued: 04/04/1989
• Est. Priority Date: 07/21/1987
• Status: Expired due to Fees

• Current Assignee: The United States of America As Represented By The Secretary of Agriculture
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Taylor, Charles J., Grossman, Julius, Smith, Howard A., Fischer, Jacqueline, Peckerar, Martin C., Rebbert, Milton L.
• Primary Examiner(s): Dees, Jose G.
• Application Number:
  US07/079,962
• Time in Patent Office: 623 Days
• Field of Search: 430/314, 430/315, 430/4, 430/6, 430/321, 430/323, 430/324, 430/320, 430/329, 204/15
• US Class Current: 430/320
• CPC Class Codes: G03F 1/20 Masks or mask blanks for imaging by charged particle beam [CPB] radiation, e.g. by electron beam; Preparation thereof
• CPC Class Codes: G03F 7/12 Production of screen printing forms or similar printing forms, e.g. stencils

Abstract

A method of fabricating a free-standing wire mesh grid pattern having a sth, flat surface is disclosed. A thermal oxide is selectively applied to front and back sides of a silicon substrate. A central portion of the oxide on the back side is removed. A resist layer is applied onto the oxide on the front side of the substrate. A resist mesh pattern with a border encompassing that resist mesh pattern is lithographically developed on the resist layer. Chrome and gold layers are sequentially deposited onto the border and into the resist mesh pattern to create a wire mesh pattern within the resist mesh pattern. The resist layer, including the developed resist mesh pattern, is removed to expose the wire mesh pattern from the front side of the substrate. A nickel layer is deposited over the gold layer to develop a wider wire mesh pattern. A second gold layer is then deposited over the nickel layer to form a wire mesh grid pattern composed of chrome, gold, nickel and gold layers. Central portions of the substrate and the oxide on the front side of the substrate are removed to expose the wire mesh grid pattern from the back side of the substrate. Finally, the chrome layer is removed to produce the desired free-standing wire mesh grid pattern supported by the encompassing metal-clad border.

Claims

1. A method for fabricating a free-standing, thin membrance that has a smooth surface containing a desired pattern of holes extending through the thickness of the membrane, said method comprising the steps of:

applying a photoresist material to the front side of a substrate;

lithographically developing a preselected pattern in the photoresist material;

depositing a first material into the preselected pattern to form an inner pattern within the preselected pattern;

removing from the front side the photoresist material and any first material on that photoresist material to expose the inner pattern;

depositing a second material onto the exposed portion of the first material to develop the desired pattern; and

removing the substrate to produce the free-standing thin membrance having a smooth surface containing the desired pattern of holes extending through the thickness of the membrane.

2. A method for fabricating a free-standing, thin membrane that has a smooth surface containing a desired pattern of holes extending through the thickness of the membrane, said method comprising the steps of:

applying a photoresist material to the front side of a substrate;

lithographically developing a preselected pattern in the photoresist material;

sequentially depositing first and second materials into the preselected pattern to form an inner pattern within the preselected pattern;

removing from the front side the photoresist material and any first and second materials on that photoresist material to expose the inner pattern;

depositing a third material onto exposed portions of the first and second materials to develop a widened inner pattern;

depositing a fourth material onto the third material to develop the desired pattern;

removing the substrate to expose the desired pattern; and

removing the first material from the desired pattern to produce the desired, free-standing, thin membrane having a smooth surface containing the desired pattern of holes extending through the thickness of the membrane.

3. A method for fabricating a free-standing, thin membrane that has a smooth surface containing a desired pattern, said method comprising the steps of:

selectively depositing a first material on both front and back sides of a substrate having a smooth, flat surface;

removing a central portion of the first material on the back side of the substrate;

applying a photoresist material to the front side of the substrate;

lithographically developing in the photoresist material on the front side of the substrate a preselected pattern;

sequentially depositing second and third materials into the preselected pattern to form an inner pattern within the preselected pattern;

removing from the front side the photoresist material and any second and third materials on that photoresist material to expose the inner pattern;

depositing a fourth material onto the third material on the inner pattern to develop a widened inner pattern;

depositing the third material onto the fourth material on the widened inner pattern to develop the desired pattern;

sequentially removing central portions of the substrate and first material on the front side of the substrate to expose the desired pattern; and

removing the second material from the desired pattern to produce the desired, free-standing, thin membrane.

4. A method for fabricating a self-supporting, thin-film, desired metallic mesh, said method comprising the steps of:

selectively depositing an oxide material on each of front and back sides of a silicon substrate;

removing a central portion of the oxide material on the back side of the substrate;

applying a photoresist layer to the front side of the substrate;

lithographically developing in the photoresist layer a preselected mesh pattern and a preselected border encompassing the preselected pattern;

sequentially depositing chrome and gold layers onto the preselected border and into the preselected mesh pattern to form an inner mesh pattern within the preselected mesh pattern;

removing from the front side any remaining portions of the photoresist layer and any chrome and gold on such remaining portions to expose the inner mesh pattern and preselected border;

depositing a nickel layer onto the gold layer to develop a widened inner mesh pattern;

depositing a second gold layer onto the nickel layer to form a desired mesh pattern;

sequentially removing central portions of the silicon substrate and oxide material on the front side of the substrate to expose the desired mesh pattern; and

removing the chrome layer from the desired mesh pattern to produce the desired self-supporting metallic mesh.

5. A method for fabricating a free-standing, thin-film, metallic mesh having a smooth, flat surface containing a desired pattern, said method comprising the steps of:

selectively depositing silicon dioxide layers on the front and back sides of a silicon substrate, with the back side layer being thicker than the front side layer;

etching away a central portion of the back side layer of silicon dioxide;

applying a photoresist layer to the front side layer of silicon dioxide;

exposing the photoresist layer to a preselected mesh pattern;

lithographically developing the exposed photoresist layer to produce the preselected mesh pattern and a preselected border encompassing the preselected mesh pattern and disposed outside of the etched away central portion of the back side layer of silicon dioxide;

depositing a layer of chrome into the preselected mesh pattern and onto the preselected border;

depositing a layer of gold over the layer of chrome to form an inner pattern within the preselected mesh pattern;

removing the developed photoresist layer and any chrome and gold on undeveloped portions of the photoresist layer to expose the inner pattern;

electroplating the gold layer of the chrome-gold layers with a layer of nickel to increase the thickness and line width of the inner pattern of chrome-gold layers;

electroplating the nickel layer of the chrome-gold-nickel layers with a second layer of gold to form the desired pattern;

etching away that portion of the silicon substrate within the etched away central portion of the back side layer of silicon dioxide;

etching away the central portion of the front side layer of silicon dioxide to expose the desired metallic mesh; and

etching away the chrome layer to produce the free-standing, thin-film, desired metallic mesh having a smooth, flat surface and containing the desired pattern.