US 9,810,916 B2
Reticle with reduced transmission regions for detecting a defocus condition in a lithography process
Akihiro Tobioka, Yokkaichi (JP)
Assigned to SanDisk Technologies LLC, Plano, TX (US)
Filed by SanDisk Technologies Inc., Plano, TX (US)
Filed on Oct. 13, 2015, as Appl. No. 14/882,258.
Claims priority of provisional application 62/182,396, filed on Jun. 19, 2015.
Prior Publication US 2016/0370598 A1, Dec. 22, 2016
Int. Cl. G02B 27/32 (2006.01); G02B 5/02 (2006.01); G03F 1/44 (2012.01); G03F 7/20 (2006.01)
CPC G02B 27/32 (2013.01) [G02B 5/0278 (2013.01); G03F 1/44 (2013.01); G03F 7/70641 (2013.01)] 17 Claims
OG exemplary drawing
 
1. A reticle, comprising:
a glass plate comprising a top surface and a bottom surface, the glass plate comprising a region with a first transmission factor and a first reduced transmission region with a second transmission factor, which is lower than the first transmission factor; and
an opaque material on the bottom surface of the glass plate, wherein a first opening is formed in the opaque material, and the first reduced transmission region is along a first optical path in the glass plate, the first optical path extends between the top surface and the first opening, at a non-perpendicular angle relative to the bottom surface of the glass plate.