High contrast alignment marker for integrated circuit fabrication
AssigneeIntel Corporation
InventorsC. Norman Ahlquist, Yaw Wen Hu, Peter F. Schoen, Paul A. Poenisch
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Abstract
A wafer marker is described for aligning masks with the wafer. The marker comprises a depression in the wafer which is defined by sloped sides and a pitted bottom. The sloped sides and pitted bottom do not directly reflect light as does the surface of the surrounding silicon and thus the marker appears as a darker region. The bottom of the depression is pitted by exposing the anode during a silicon plasma etching step.
Claims5
In the fabrication of integrated circuits on a substrate wherein radiation is passed through a masking member to expose certain regions of a photosensitive layer, a process for forming an improved marker for permitting better alignment between said masking member and said substrate, comprising the steps of:
- forming a photoresist layer on said substrate;
- forming an opening in said layer at the proposed site of said marker;
- etching a depression in said substrate in said substrate at said opening, said depression including sloped sides and a generally planer bottom region;
- roughening said bottom region such that said bottom region directly reflects less radiation than said substrate surface;
- whereby a high contrast marker for use in aligning said masking member with said substrate is formed.
In the fabrication of integrated circuits on a substrate wherein radiation is passed through a masking member to expose certain regions of a photosensitive layer, a process for forming an improved contrast marker for permitting better alignment between said masking member and said substrate, comprising the steps of:
- forming a photoresist layer on said substrate;
- forming an opening on said layer at the proposed site of said marker;
- etching a depression in said substrate at said opening, said depression including sloped sides and a generally planer bottom region;
- roughening said bottom region such that said bottom region directly reflects less radiation than said substrate surface;
- removing said photoresist layer from said substrate;
- forming a second photoresist layer which covers said depression, said second layer having a uniform thickness over said surface of said substrate;
- whereby a high contrast marker for use in aligning said masking member with said substrate is formed.
Dependencies are inferred from the claim text.