Wiring substrate features having controlled sidewall profiles
AssigneeKulicke & Soffa Holdings, Inc.
InventorsTed T. Chen, Michael P. Skinner
Life of this patent
Estimating the term…
Abstract
A dielectric layer in a wiring substrate having a sloped sidewall. A photomask used to pattern the dielectric layer includes optical proximity features. The size and spacing of the optical proximity features are generally less than the resolution limit of the exposure tool used and do not print out on the layer. The optical proximity features provide a transition region between fully exposed material and un-exposed material, which results in a sloped sidewall of the photo-sensitive material after development. The sloped sidewall provides a more reliable thin film metal layer to contact through vias, and may be used to conserve wiring board area by allowing smaller via spacing.
Claims30
A method for controlling a sidewall profile of an opening in a layer of photosensitive material, the method comprising:
- forming a layer of photosensitive material on a substrate;
- exposing selected portions of the layer of photosensitive material to light from a light source through a photomask, the photomask having selected optical proximity features, to form an exposed portion, an unexposed portion, and a transition portion of the layer, wherein both a size and a spacing of the selected optical proximity features is equal to or smaller than a resolution limit for an exposure tool employed in the exposing of the selected portions;
- and
- developing the layer of photosensitive material to form an opening in the layer, the opening having a sloping sidewall.
A method of forming a contact via in a thin-film stack of a printed wiring substrate, the method comprising:
- forming a layer of photosensitive dielectric material on a substrate;
- exposing the layer of photosensitive dielectric material to light from a light source through a photomask, the photomask having a via photo-pattern including optical proximity elements disposed around a first portion of a perimeter of the via photo-pattern and excluding optical proximity elements around a second portion of the perimeter of the via photo-pattern, to form an exposed portion, a non-exposed portion, and a transition portion of the layer of photosensitive dielectric material, wherein both a size and a spacing of the optical proximity elements is equal to or smaller than a resolution limit for an exposure tool employed in the exposing of the layer of photosensitive dielectric material;
- and
- developing the layer of photosensitive dielectric material to remove a first portion of the photosensitive dielectric material to thereby form a via opening with a sloped sidewall portion of the via opening corresponding to the first portion of the perimeter of the via photo-pattern.
A method for controlling a sidewall profile of an opening in a layer of photosensitive material, the method comprising:
- forming a layer of photosensitive material on a substrate, the layer having an upper surface and a lower surface;
- exposing selected portions of the layer of photosensitive material to light from a light source through a photomask, the photomask having transparent and opaque portions and having selected optical proximity features, to form an exposed portion, an unexposed portion, and a transition portion of the layer, wherein both a size and a spacing of the selected optical proximity features is equal to or smaller than a resolution limit for an exposure tool employed in the exposing of the selected portions;
- and
- developing the layer of photosensitive material to form an opening through the layer, the opening having a sloping sidewall that results in the opening in the upper surface being larger than an opening in the lower surface.
A method of forming a contact via in a thin-film stack of a printed wiring substrate, the method comprising:
- forming a layer of photosensitive dielectric material on a substrate, the layer having an upper surface and a lower surface;
- exposing the layer of photosensitive dielectric material to light from a light source through a photomask, the photomask having transparent and opaque portions and having a via photo-pattern including optical proximity elements disposed around a first portion of a perimeter of the via photo-pattern and excluding optical proximity elements around a second portion of the perimeter of the via photo-pattern, to form an exposed portion, a non-exposed portion, and a transition portion of the layer of photosensitive dielectric material, wherein both a size and a spacing of the optical proximity elements is equal to or smaller than a resolution limit for an exposure tool employed in the exposing of the layer of photosensitive dielectric material;
- and
- developing the layer of photosensitive dielectric material to remove a first portion of the photosensitive dielectric material to thereby form a via opening with a sloped sidewall portion that results in the via opening in the upper surface being larger than the via opening in the lower surface.
Dependencies are inferred from the claim text.