Back-end processes for substrates re-use
View Patent ↗A method for fabricating optical devices on a reusable handle substrate. The method includes providing a handle substrate having a surface region. The method also includes forming a plurality of optical device using at least an epitaxial growth process overlying the surface region and then releasing the handle substrate from the plurality of optical devices. The method reuses the handle substrate for another fabrication process.
1. A method for fabricating a plurality of optical devices comprising:
providing a bulk substrate having a top surface;
forming a liftoff layer on the top surface of the bulk substrate;
forming at least two layers of semiconductor material on the liftoff layer, the at least two layers of semiconductor material having an upper surface;
dividing the at least two layers of semiconductor material into separate die regions electrically isolated from each other by forming trenches through the at least two layers of semiconductor material and through the liftoff layer down to the bulk substrate;
attaching the upper surface of the now separate die regions to a layer of adhesive material;
using the liftoff layer, separating the at least two layers of semiconductor material from the bulk substrate;
expanding the layer of adhesive material to move the die regions further apart from each other;
by use of the layer of adhesive material, positioning the die regions on a first substrate for further processing;
affixing the die regions to the first substrate;
reusing the bulk substrate for a subsequent process.
2. A method as in claim 1 wherein after the step of expanding the adhesive layer, the layer of adhesive material is used to position the die regions on a carrier.
3. A method as in claim 1 wherein the at least two layers of semiconductor material provide a light emitting diode.
4. A method as in claim 1 wherein after expanding the layer of adhesive material to move the die regions further apart from each other; the die regions are transferred to a first sheet of Kapton film.
5. A method as in claim 4 wherein the first sheet of Kapton film is used to position separate die regions on one surface of the first substrate.
6. A method as in claim 5 further comprising affixing a second sheet of Kapton film to an opposite surface of the first substrate.
7. A method as in claim 6 further comprising subjecting the first substrate with the first and second sheets of Kapton film to a vacuum.
8. A method as in claim 7 wherein following the step of subjecting the substrate to a vacuum, a step of heating the substrate is performed to attach the die regions to the first substrate.
9. A method as in claim 1 wherein the step of expanding comprises use of a tape ring.
10. A method as in claim 1 further comprising using a vacuum chuck to mate with the die regions and position the die regions over the first substrate to which the die regions subsequently are attached.
11. A method as in claim 10 wherein the vacuum chuck is used for positioning the die regions and then mating the die regions to the first substrate.
12. A method as in claim 11 wherein the first substrate includes metallized regions to which the die regions are bonded.