Method of manufacturing a liquid crystal device
View Patent ↗A wafer level method of manufacturing a liquid crystal optical device removes the need for a rigid barrier fillet while minimizing any risk of contamination of the liquid crystal. An uncured adhesive may be deposited on a bottom substrate and partially cured to form a liquid crystal barrier. After addition of the liquid crystal and a top substrate, the adhesive is fully cured to bond the substrate layers together. An uncured adhesive may be used together with the partially cured adhesive, and may be deposited separately or filled into an extracellular matrix surrounding a plurality of liquid crystal cells. The adhesive may be cured by a variety of means, including light that may be spatially modulated. One or both of the substrates may be deformed during assembly so as to create a structure with a lensing effect on light passing through the liquid crystal region.
1. A method of manufacturing a liquid crystal device comprising:
providing on a bottom substrate an array of liquid crystal retaining walls that define liquid crystal cells and an extracellular matrix that surrounds the liquid crystal cells,
providing liquid crystal on the substrate within the liquid crystal cells;
placing a top substrate in opposition to the bottom substrate so as to enclose the liquid crystal between the top and bottom substrates and the retaining walls;
filling the extracellular matrix with a filling adhesive that bonds together the top and bottom substrate to form a wafer, wherein the filing adhesive provides support for mechanical singulation; and
dicing the wafer to singulate the liquid crystal cells.
2. The method as claimed in claim 1 wherein providing an array of retaining walls comprises depositing a retaining wall adhesive material on the bottom substrate and at least partially curing the retaining wall adhesive material prior to the addition of the liquid crystal.
3. The method as claimed in claim 2 wherein said at least partially curing of the retaining wall adhesive comprises at least partially curing a first portion of the retaining wall adhesive that resides adjacent to the liquid crystal cell and curing to a significantly lesser degree a second portion of said retaining wall adhesive further from the liquid crystal cell than the first retaining wall adhesive portion.
4. The method as claimed in claim 1 further comprising fixing a spacing between the top substrate and the bottom substrate by one of: holding the top substrate with respect to the bottom substrate at a desired distance and locating spacers between the top substrate and the bottom substrate so as to fix a spacing therebetween.
5. The method as claimed in claim 2 wherein said retaining wall adhesive is light curable, and said partly curing is performed using spatially modulated light.
6. The method as claimed in claim 5 wherein partially curing said retaining wall adhesive comprises partially curing said adhesive using light passing through a mask.
7. The method as claimed in claim 5 wherein partially curing said retaining wall adhesive comprises partially curing said retaining adhesive using a light source that directs light to a first portion of the retaining wall adhesive that is adjacent to the liquid crystal region.
8. The method as claimed in claim 1 wherein the filling adhesive is deposited in an uncured state and wherein the method further comprises curing the filling adhesive.
9. The method as claimed in claim 1 further comprising a peripheral barrier that surrounds a plurality of the liquid crystal cells and defines an outer wall of the extracellular matrix.
10. The method as claimed in claim 1 , wherein said liquid crystal device is a lens.
11. The method as claimed in claim 10 , wherein the lens is a GRIN lens.
12. The method as claimed in claim 1 , wherein filling the extracellular matrix with a filling adhesive comprises vacuum filing the extracellular matrix with the filling adhesive.
13. The method as claimed in claim 1 , wherein filling the extracellular matrix with a filling adhesive comprises allowing the filling adhesive to seep into the extracellular matrix via capillary action.
14. The method as claimed in claim 1 , wherein filling the extracellular matrix with a filling adhesive comprises pumping bonding agent from a bottom of a vertically oriented wafer, wherein pumping bonding agent from the bottom reduces air pockets.