Alignment or overlay marks for semiconductor processing
AssigneeInfineon Technologies AG
InventorsEnio Carpi, Shoaib Hasan Zaidi
Life of this patent
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Abstract
An alignment or overlay mark with improved signal to noise ratio is disclosed. Improved signal-to-noise ratio results in greater depth of focus, thus improving the performance of the alignment mark. The alignment mark comprises a zone plate having n concentric alternating opaque and non-opaque rings. Light diffracted by either the odd or even rings are cancelled while light diffracted by the other of the odd or even rings are added.
Claims37
A semiconductor wafer comprising:
- a first plurality of alignment marks disposed in a first level overlying a substrate, each alignment mark in the first plurality comprising a zone plate that comprises n concentric alternating opaque and non-opaque rings;
- a second plurality of alignment marks disposed in a second level that overlies the first level, each alignment mark in the second plurality comprising a zone plate that comprises n concentric alternating opaque and non-opaque rings.
An alignment mark for processing comprising a zone plate formed on a substrate, the zone plate comprises n concentric alternating opaque and non-opaque rings, wherein the zone plate increases signal-to-noise ratio of the alignment over conventional alignment marks, wherein the opaque rings comprise an opaque material and the non-opaque rings comprise a non-opaque material, the alignment mark further comprising additional zone plates, wherein the zone plate and the additional zone plates are arranged in a line or other geometric shape, and wherein the first ring comprises an opaque ring.
An alignment mark for processing comprising a zone plate formed on a substrate, the zone plate comprises n concentric alternating opaque and non-opaque rings, wherein the zone plate increases signal-to-noise ratio of the alignment over conventional alignment marks, wherein the opaque rings comprise an opaque material and the non-opaque rings comprise a non-opaque material, the alignment mark further comprising additional zone plates, wherein the zone plate and the additional zone plates are arranged in a line or other geometric shape, and wherein the first ring comprises a non-opaque ring.
In processing, a method of forming a semiconductor device comprising:
- providing a substrate;
- forming a first alignment mark over the substrate, the alignment mark comprising a zone plate having n concentric alternating opaque and non-opaque rings;
- forming a second alignment mark in a layer that overlies the first alignment mark, the second alignment mark comprising a zone plate having n concentric alternating opaque and non-opaque rings;
- and
- determining a relationship between relative lateral positions of the first and second alignment marks.
A method of aligning wafer to a mask, the method comprising:
- providing a wafer prepared with a plurality of alignment marks arranged at the periphery of active circuitry, wherein each alignment mark comprises a zone plate having n concentric alternating opaque and non-opaque rings;
- detecting the alignment marks with an alignment system;
- and
- moving either the wafer or mask into position based on the alignment marks.
Dependencies are inferred from the claim text.