Method of forming a marker, substrate having a marker and device manufacturing method
AssigneeASML Netherlands B.V.
InventorsRichard Johannes Franciscus Van Haren, Maurits Van der Schaar
Life of this patent
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Abstract
A marker, for example an alignment marker or an overlay marker is formed in two steps. First, a pattern of two chemically distinct feature types having a pitch comparable to product features is formed. This pattern is then masked by resist in the form of the desired marker, which has a larger pitch than the pattern. Finally, one of the two feature types is selectively etched in the open areas. The result is a marker with a large pitch suitable to be read with long wavelength radiation but the edges of the features are defined in an exposure step having a pitch comparable to the product features.
Claims15
A method of forming a marker on a substrate, the method comprising:
- exposing the substrate to define a first pattern in an area of the substrate, the first pattern having a pitch P1;
- transferring the first pattern into the substrate to form an array of alternating first and second features having a pitch P1;
- exposing the substrate to define a second pattern comprising third features over the array of alternating first and second features, the second pattern having a pitch P2, wherein P2 is greater than P1;
- and
- selectively chemically processing the substrate to alter one of the first and second features exposed by open areas of the second pattern in preference to the other of the first and second features.
Dependencies are inferred from the claim text.