Interface for a-Si waveguides and III/V waveguides
A method of coupling a waveguide to a multi-layered active device structure on a substrate is described. The method includes forming a junction area by etching the active device structure to form a sloped etch profile with respect to the substrate, aligning multiple layers of the multi-layered active device structure via an etch stop adjacent the multi-layered active device structure, and depositing the waveguide over the etched active device structure, wherein a sloped active passive junction is formed at the junction area that reduces residual interface reflection in a resulting coupled device. Also described is a method for removing at least one laser layer in a sloped junction region forming passive amorphous silicon waveguides. This includes depositing a SiN layer for use as an etch mask, patterning a photoresist mask, patterning the SiN layer by reactive ion etching, stripping the photoresist mask, and etching the at least one laser layer.
1. A method for etching laser layers of a wafer when forming a sloped junction region to passive amorphous silicon waveguides, comprising:
etching an InGaAs cap portion with H 2 SO 4 :H 2 O 2 :H 2 O;
etching a first InP layer with HCl:H 3 PO 4 ;
rinsing said wafer with NH 4 OH:H 2 O;
reactive ion etching an InGaAsP layer with a gas mixture, wherein said reactive ion etching forms a plasma polymer deposited on said wafer;
removing said plasma polymer in an O 2 plasma;
etching a second InP layer with HCl:H 3 PO 4 ;
rinsing said wafer with NH 4 OH:H 2 O after etching said second InP portion;
reactive ion etching a second InGaAsP layer and a third InP layer with said gas mixture, wherein said reactive ion etching forms a second plasma polymer deposited on said wafer;
removing said second plasma polymer in an O 2 plasma; and
etching a final InP layer with HCl:H 3 PO 4 .
2. The method of claim 1 , wherein the ratio of said H 2 SO 4 :H 2 O 2 :H 2 O for etching said InGaAs cap portion is approximately 10:1:1.
3. The method of claim 1 , wherein the ratio of said HCl:H 3 PO 4 for etching said first, second and final InP layers is approximately 3:1.
4. The method of claim 1 , wherein the ratio of said NH 4 OH:H 2 O for said first and second rinsing of said wafer is approximately 1:20, and wherein said wafer is spin dried after each of said rinsings.
5. The method of claim 1 , wherein said gas mixture for said reactive ion etching comprises 4.4 sccm Ar, 11 sccm CH 4 and 15 sccm H 2 at 20 mT with 250 W.
6. A method of coupling a waveguide to a multi-layered active device structure on a substrate, comprising:
aligning multiple layers of a multi-layered active device structure via an etch stop adjacent said multi-layered active device structure;
forming a junction area by etching said active device structure to form a sloped etch profile with respect to said substrate, including:
etching an InGaAs cap portion with H 2 SO 4 :H 2 O 2 :H 2 O;
etching a first InP layer with HCl:H 3 PO 4 ;
rinsing said wafer with NH 4 OH:H 2 O;
reactive ion etching an InGaAsP layer with a gas mixture, wherein said reactive ion etching forms a plasma polymer deposited on said wafer;
removing said plasma polymer in an O 2 plasma;
etching a second InP layer with HCl:H 3 PO 4 ;
rinsing said wafer with NH 4 OH:H 2 O after etching said second InP portion;
reactive ion etching a second InGaAsP layer and a third InP layer with said gas mixture, wherein said reactive ion etching forms a second plasma polymer deposited on said wafer; and
removing said second plasma polymer in an O 2 plasma; and
etching a final InP layer with HCl:H 3 PO 4 ;
depositing a waveguide over said etched active device structure, wherein a sloped active passive junction is formed at said junction area resulting in a coupled device;
depositing a SiN layer for use as an etch mask;
patterning a photoresist mask;
patterning said SiN layer by reactive ion etching;
stripping said photoresist mask; and
etching at least a portion of said coupled device to reduce residual interface reflection in the coupled device.