Epitaxial lift off systems and methods
View Patent ↗Epitaxial lift off systems and methods are presented. In one embodiment a tape is disposed on the opposite side of the epitaxial material than the substrate is used to hold the epitaxial material during the etching and removal steps of the ELO process. In various embodiments, the apparatus for removing the ELO film from the substrates without damaging the ELO film may include an etchant reservoir, substrate handling and tape handling mechanisms, including mechanisms to manipulate (e.g., cause tension, peel, widen the etch gap, etc.) the lift off component during the lift off process.
1. A system comprising:
an etchant application component configured to apply etchant to a sacrificial layer disposed between an epitaxial lift off component and a growth substrate of a plurality of growth substrates processed by the system, wherein the etchant application component comprises a substrate handling belt having a plurality of substrate pockets each of which is configured to receive one of the growth substrates and hold the etchant within, along with the respective growth substrate, wherein the etchant application component further comprises an etchant supply component configured to deliver the etchant to each growth substrate and the respective substrate pocket to fill the substrate pocket with the etchant, and wherein at least a portion of a surface of each substrate pocket contacts the growth substrate therein;
a separation assistance component configured to manipulate the epitaxial lift off component to assist separation of the epitaxial lift off component from the growth substrate, wherein manipulation of the epitaxial lift off component is controlled to facilitate exposure of an etchant to an etch face of the sacrificial etch layer; and
a tape application component configured to couple the epitaxial lift off component to a tape, wherein the tape assists the manipulation and transportation of the epitaxial lift off component while etchant is applied to the sacrificial layer.
2. The system of claim 1 wherein the manipulation by the separation assistance component includes applying a force to increase a gap distance between portions of the epitaxial lift off component and the growth substrate prior to final separation.
3. The system of claim 2 wherein the force is applied to the tape and the tape pulls on the epitaxial lift off component.
4. The system of claim 1 wherein the manipulation by the separation assistance component includes applying a force to assist mitigation of adverse impacts associated with final separation of the epitaxial lift off component from the growth substrate.
5. The system of claim 1 wherein the separation assistance component comprises:
a drive link ramp comprising an elongated slot and having a height that increases from the first end to a second end through the etching section; and
a chain drive comprising a plurality of drive pins, the plurality of drive pins extending through the plurality of slots in the tape and into the elongated slots, wherein the chain drive drives the tape along the drive link ramp causing the sides of the tape to be driven along and up the increasing height of the drive link ramps.
6. The system of claim 5 wherein the separation assistance component further comprises a plurality of point loads that contact the center of the tape as the tape is driven along and up the increasing height of the drive link ramps.
7. The system of claim 1 wherein the separation assistance component comprises:
a guide rail including a slot that receives one side of the tape, and a plurality of index pin receiving holes; and
a pin rail including a plurality of index pins;
wherein the pin rails are operable to be lowered with respect to the guide rails such that the plurality of index pins extend into the index pin receiving holes and through the plurality of slots along the sides of the tape; and wherein the pin rails and the guide rails are operable to raise the sides of the tape.
8. The system of claim 7 wherein said separation assistance component further comprises a weight bar that provides force on a center of the tape and the growth substrate.
9. The system of claim 1 wherein the separation assistance component comprises:
a plurality of roller drive shafts, each roller driveshaft supporting one roller of the series of rollers;
a plurality of driven miter gears, each miter gear mounted on the end of one of the plurality of roller drive shafts; and
a gear driveshaft including a plurality of driving miter gears, each driving miter gear engaging one of the driven miter gears, such that when the gear driveshaft is driven the series of rollers rotate to support the tape and a substrate assembly as it proceeds through an etching section.
10. The system of claim 1 wherein the etchant supply component comprises a plurality of etching spray nozzles that direct an etchant spray toward the portion of the tape to which the epitaxial liftoff component is coupled, and toward the growth substrate and the respective substrate pocket, either continuously or periodically.
11. The system of claim 1 wherein the plurality of substrate pockets in the substrate handling belt are configured in a linear arrangement along a length of the substrate handling belt.
12. The system of claim 1 wherein the etchant supply component is configured to deliver the etchant to each substrate pocket to fill the substrate pocket with the etchant prior to having the substrate pocket receive the respective growth substrate.
13. An epitaxial lift off system comprising:
a wafer receiving stage wherein each wafer processed by the system includes a substrate, a sacrificial etch layer, an epitaxial lift off component, wherein each substrate is supported by a substrate pocket of a plurality of substrate pockets in a substrate handling belt, wherein each substrate pocket is configured to receive the substrate and hold etchant within, along with the respective growth substrate, and an etchant supply component configured to deliver the etchant to the substrate and the respective substrate pocket to fill the substrate pocket with the etchant, and wherein at least a portion of a surface of the substrate pocket contacts the substrate therein;
a tape coupling application stage, wherein the epitaxial lift off component of each wafer is coupled to a tape; and
an etching stage wherein the lift off component is manipulated to assist etchant exposure to an etch face of the sacrificial etch layer and aid separation of the epitaxial lift off component from the substrate.
14. The epitaxial lift off system of claim 13 further comprising a clean and rinse stage wherein the epitaxial lift off component and the tape are cleaned and rinsed.
15. The epitaxial lift off system of claim 13 further comprising a tape receiving stage configured to receive the tape.
16. The epitaxial lift off system of claim 13 further comprising a tape receiving stage wherein the tape is received and prepared for participating in further portions of the epitaxial lift off system.
17. The epitaxial lift off system of claim 13 wherein the plurality of substrate pockets in the substrate handling belt are configured in a linear arrangement along a length of the substrate handling belt.
18. The epitaxial lift off system of claim 13 wherein the etchant supply component is configured to deliver the etchant to each substrate pocket to fill the substrate pocket with the etchant prior to having the substrate pocket receive the respective growth substrate.