Systems and fabrication methods for display panels with integrated micro-lens array
Various embodiments include a display panel with an integrated micro-lens array. The display panel typically includes an array of mesas which includes an array of pixel light sources (e.g., LEDs) electrically coupled to corresponding pixel driver circuits (e.g., FETs). The array of micro-lenses is aligned to the mesas including the pixel light sources, and positioned to reduce the divergence of light produced by the pixel light sources. In some embodiments, the array of micro-lenses formed from a micro-lens material layer is formed directly on top of the mesas. The display panel may also include an integrated optical spacer formed from the same micro-lens material layer to maintain the positioning between the micro-lenses and pixel driver circuits.
1. A method of fabricating a light emitting pixel unit, comprising:
providing a substrate;
forming at least one mesa on the substrate; and
depositing a micro-lens material layer directly by a chemical vapor deposition process on at least a top of the at least one mesa, the micro-lens material layer forming at least one micro-lens with a shape of hemisphere on the at least one mesa during the chemical vapor deposition process by conforming to a shape of the at least one mesa,
wherein
a height of the at least one micro-lens is not more than 2 micrometers, and a width of the at least one micro-lens is not more than 4 micrometers,
a thickness of a micro-lens of the at least one micro-lens at a center top of a mesa of the at least one mesa is thicker than a thickness of the micro-lens at an edge top of the mesa to reduce a divergence of light produced by the mesa, and,
the shape of hemisphere of the micro-lens material layer, and a positioning of the shape of hemisphere to reduce the divergence of light produced by the at least one mesa are formed during the deposition by the chemical vapor deposition process.
2. The method of fabricating the light emitting pixel unit according to claim 1 ,
wherein:
material of the micro-lens material layer is different from material of the at least one mesa.
3. The method of fabricating the light emitting pixel unit according to claim 1 , wherein the micro-lens forms individually during the deposition by the chemical vapor deposition process around the top of the mesa.
4. The method of fabricating the light emitting pixel unit according to claim 1 , wherein a spacer is formed from the same micro-lens material layer between the at least one mesa and the micro-lens.
5. The method of fabricating the light emitting pixel unit according to claim 4 , wherein material of the spacer is as the same as material of the micro-lens.
6. The method of fabricating the light emitting pixel unit according to claim 1 , wherein the micro-lens is composed of a dielectric material.
7. The method of fabricating the light emitting pixel unit according to claim 1 , wherein material of the micro-lens is photoresist.
8. The method of fabricating the light emitting pixel unit according to claim 1 , wherein the height of the micro-lens is not more than 1 micrometer.
9. The method of fabricating the light emitting pixel unit according to claim 1 , wherein the width of the micro-lens is not more than 3 micrometers.
10. The method of fabricating the light emitting pixel unit according to claim 1 , wherein, on the substrate, the mesa is within a matrix of mesa array, and the micro-lens is within a matrix of micro-lens array deposited and formed in the shape of hemisphere during the chemical vapor deposition process according to placement of the mesa array.
11. The method of fabricating the light emitting pixel unit according to claim 1 , wherein the shape of the micro-lens is hemisphere when the top of the mesa is flat.
12. The method of fabricating the light emitting pixel unit according to claim 1 , wherein the at least one mesa includes at least a light emitting device.
13. The method of fabricating the light emitting pixel unit according to claim 1 , wherein parameters of the chemical vapor deposition process used to deposit the micro-lens material layer and forming the shape of hemisphere on the at least one mesa include: power is less than 1000 W, pressure is between 100 milli-torr to 2000 milli-torr, temperature is between 23° C. to 500° C., gas flow rate is less than 3000 sccm, and time is between 1 hour to 3 hours.
14. The method of fabricating the light emitting pixel unit according to claim 1 , further comprising: patterning the micro-lens material layer to expose an electrode area of the substrate.
15. The method of fabricating the light emitting pixel unit according to claim 14 , wherein patterning further includes:
forming a mask on surface of the micro-lens material;
patterning the mask via a photolithography process, thereby forming openings in the mask and exposing the micro-lens material layer above the electrode area of the at least one mesa; and
with the mask protection in place, etching portions of the micro-lens material layer exposed by the openings.
16. The method of fabricating the light emitting pixel unit according to claim 15 , wherein etching is a wet etching method.