Distributed bragg reflector and method of fabrication
View Patent ↗A distributed Bragg reflector and a method of fabricating the same incorporates a support for supporting the gaps against collapse. The method includes forming a plurality of alternating structure and sacrificial layers on a substrate. The structure and sacrificial layers are etched into at least one mesa protruding from the substrate. A support layer is formed on the at least one mesa leaving a portion of the structure and sacrificial layers exposed. At least a portion of at least one of the exposed sacrificial layers are etched from between the structure layers to form gaps between the structure layers.
1. A method of fabricating a Bragg reflector comprising:
forming at least one structure layer and at least one sacrificial layer in alternating relation on a substrate;
etching the structure and sacrificial layers into at least one mesa protruding from the substrate;
forming a support layer on the at least one mesa leaving a portion of the structure and the sacrificial layers exposed; and
etching at least a portion of at least one of the exposed sacrificial layers to form a gap.
2. The method of claim 1 wherein forming a support layer on the at least one mesa comprises masking a portion of the mesa to prevent deposition of the support layer on the portion of the mesa.
3. The method of claim 2 wherein forming a support layer is depositing the support layer in a chemical vapor deposition process and wherein the mask is a dielectric mask.
4. The method of claim 1 wherein the material of the structure layer and the material of the support layer comprise substantially the same material.
5. The method of claim 1 wherein the structure layer material is different than a sacrificial layer material, and wherein etching at least a portion of at least one of the exposed sacrificial layers comprises etching the sacrificial layers without substantially etching the structure layers.
6. The method of claim 5 wherein etching further comprises etching without substantially etching the support layer.
7. The method of claim 1 wherein the sacrificial layer comprises a material selected from the group consisting of InGaAs, AlAs, and SiO 2 and the structure layer comprises a material selected from the group consisting of InP, GaAs, and Si.
8. The method of claim 7 wherein the support layer comprises a material selected from the group consisting of InP, GaAs, and Si.
9. The method of claim 1 further comprising doping at least a portion of the support layer to create an electrically conductive path.
10. The method of claim 1 further comprising doping at least a portion of the support layer to make at least the portion of the support layer electrically non-conductive.