Method for three-dimensional control of solubility properties of resist layers

A method for controlling edge profiles and pattern dimensions in a lithography process, the method comprising the steps of:

• coating a substrate with a resist;
• forming a pattern in the resist using the lithography process;
• exposing the resist to a uniform electron beam;
• controlling the electron beam energy and dose so as to expose layered portions of the resist to selected degrees, thereby controlling the resulting developed edge profiles in the resist;
• and
• developing the resist to remove unwanted portions of the pattern.

A method for forming a three-dimensional structure, comprising the steps of:

• forming a resist layer on a substrate;
• selecting regions of the resist layer, each region being defined by its position and extent in three dimensions within the resist layer;
• exposing the selected regions to selected doses of electrons from a uniform blanket electron beam, to effect a change of solubility of the selected regions;
• and
• developing the resist to remove unwanted portions and leave a desired three-dimensional resist structure.

A method for forming a three-dimensional metal structure on a substrate, comprising the steps of:

• forming a thin metal layer on a substrate;
• forming a resist layer over the thin metal layer;
• selecting regions of the resist layer, each region being defined by its position and extent in three dimensions within the resist layer;
• exposing the selected regions to selected doses of electrons from a uniform blanket electron beam, to effect a change of solubility of the selected regions;
• developing the resist to remove unwanted portions and leave a desired three-dimensional cavity extending through the resist layer to the thin metal layer;
• plating metal into the substrate, to fill the cavity and bond to the thin metal layer;
• and
• removing remaining portions of the resist layer and the thin metal layer, to leave a desired three-dimensional metal structure in the shape of the cavity.

A method for producing a desired edge profile in a resist layer formed on a substrate, the method comprising the steps of:

• (a) forming a resist layer on the substrate;
• (b) patterning the resist layer using a selected lithography process to produce at least one opening in the resist layer, wherein the resist layer has generally perpendicular exposed edges around the at least one opening;
• (c) exposing the resist layer to a blanket electron beam of sufficient energy to penetrate the entire layer, at an electron dose selected to render the entire layer highly soluble to a developer, wherein this step (c) is performed only if the resist layer is a positive resist;
• (d) exposing the resist layer to a blanket electron beam of sufficient energy to penetrate only a selected upper portion of the resist layer, at an electron dose selected to render the selected upper portion insoluble to the developer;
• and
• (e) immersing the substrate and the resist layer in the developer for a time selected to remove exposed edges of the resist layer, but only below the upper portion that has been rendered insoluble by the preceding step (d), leaving the upper portion as a resist layer ledge that extends into the at least one opening;
• whereby the resist layer has a desired undercut edge profile.