Radiation imagery chemistry: process – composition – or product th – Radiation modifying product or process of making – Radiation mask
Patent
1981-01-02
1982-08-10
Downey, Mary F.
Radiation imagery chemistry: process, composition, or product th
Radiation modifying product or process of making
Radiation mask
430 22, 430311, 430312, 430394, 430396, 357 85, G03C 500
Patent
active
043438784
ABSTRACT:
A system for providing photomask alignment keys in semiconductor integrated circuit processing involving selecting a common photomask subarea to be utilized as an alignment key pattern area on each photomask in the set with the alignment key pattern area having an array of sequential key locations. Each photomask after the first has a designated alignment key location which is either the same alignment key location as the immediately preceding photomask or the next alignment key location in the array. A mask key pattern is formed on the first photomask comprising aligning keys for all the associated higher numbered photomasks designed to be aligned to topography created by use of the first photomask in accordance with a mask alignment formula with each of the aligning keys being formed at key locations corresponding to the designated alignment key locations for the associated photomask. On each of the remaining photomasks of the set a mask key pattern is formed comprising an alignment key at the designated alignment key location and aligning keys for any associated higher numbered ones of the photomasks designed in accordance with the mask alignment formula to be aligned to the topography created by use of each photomask with each of the aligning keys being formed at a key location corresponding to the designated key location for the associated photomasks. On each photomask having a mask sequence number greater than two and being the first photomask in the set to have a particular designated alignment key location, a used key pair blot mark is formed at a key location immediately preceding the designated alignment key location for the mask.
The alignment key assignment process together with the use of used key pair blot marks provides a self-instructing alignment key pattern on each photomask to avoid having to make reference to extrinsic alignment instructions.
REFERENCES:
patent: 3666463 (1972-05-01), Beynnon et al.
patent: 3690881 (1972-04-01), King
patent: 3742229 (1973-06-01), Smith et al.
patent: 4070117 (1978-01-01), Johannsmeier
patent: 4118230 (1978-10-01), Binder
Amdahl Corporation
Downey Mary F.
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