Method of thin lightshield process for solid-state image sensors
View Patent ↗An image sensor includes a substrate having photosensitive areas; an insulator spanning at least a portion of the substrate; and a first and second layer of a multi-layer metallization structure, wherein the first layer forms light shield regions over selected portions of the photosensitive area as well forming circuit interconnections and barrier regions to prevent spiking into the substrate or gates at contacts in the non-imaging area; and the second layer spanning the interconnections and barrier regions of the first layer only over the non-imaging areas and the second layer overlays edges of the first layer.
1. A method for forming an image sensor, the method comprising the steps of:
(a) providing a substrate having a plurality of photosensitive areas;
(b) providing an insulator spanning at least a portion of the substrate;
(c) providing a first layer of a multi-layer metallization structure spanning at least a portion of the insulator and spanning an opening in the insulator;
(d) a first etch removes portions of the first layer;
(e) depositing a second layer of a multi-layer metallization structure spanning at least portions of the first layer; and
(f) a second etch removes portions of the second layer so that the second layer spans at least portions of non-imaging areas.
2. The method as in claim 1 further comprising the steps of providing aluminum as the second layer and titanium and tungsten as the first layer.