Production of cavities that can be filled with a fluid material in an optical microtechnological component
A novel method makes it possible to form cavities intended to contain a liquid with determined optical properties within a film for optical use. The walls ( 38 ) of the cavities ( 40 ) are formed by plasma etching of a layer of transparent or light absorbent material ( 30, 34 ) transferred onto a microtechnological substrate, the walls ( 38 ) having a structured profile in order to limit the parasitic phenomena of light diffusion and diffraction.
1. Optical device comprising a first layer of material, a second layer of material and walls delimiting cavities between the first and second layers of material, the walls having a pair of ends and a center portion between the ends,
the walls having a biconcave structured shape so that the thickness of the ends of the walls, adjacent to the first and second layers, is greater than the thickness of the center portion of the walls,
further comprising at least a portion of a stop layer interposed between one of the ends of the walls and one of the first and second layers of material,
wherein the walls are formed of a different material than said portion of a stop layer, and
wherein the wall material is configured to be etched by plasma while the portion of a stop layer is substantially impervious to being etched by said plasma.
2. Device according to claim 1 wherein the first and the second layers are transparent, and the cavities form a leak tight assembly filled with a fluid of predetermined optical qualities.
3. Device according to claim 2 wherein the fluid is photosensitive, heat sensitive, or a liquid of determined optical index.
4. Device according to claim 1 wherein the walls comprise a transparent or light absorbing part adjacent to one of the first and second layers.
5. Device according to claim 1 wherein the walls have a height H extending between the ends, a thickness l at each of the ends, and a thickness e at the center portion, and
wherein a ratio of the thickness l and the thickness e of the walls is within the range of l/10≦e≦l/2.
6. Device according to claim 1 wherein the walls have a height H extending between the ends, a thickness l at each of the ends, and a thickness e at the center portion, and
wherein a ratio of the height H and the thickness l of the walls is within the range of 2≦H/l≦10.
7. Device according to claim 1 wherein said portion of a stop layer extends substantially along a major portion of one of the first and second layers of material.
8. Device according to claim 1 wherein the portion of a stop layer is configured to be at least partially etched by another plasma that is different than said plasma used to etch said wall material.