US 12,332,478 B2
Photonic device and methods of forming same
Yuan-Sheng Huang, Taichung (TW); and Wei-Kang Liu, Taichung (TW)
Assigned to TAIWAN SEMICONDUCTOR MANUFACTURING COMPANY, LTD., Hsinchu (TW)
Filed by Taiwan Semiconductor Manufacturing Company, Ltd., Hsinchu (TW)
Filed on Jun. 7, 2022, as Appl. No. 17/805,755.
Claims priority of provisional application 63/321,648, filed on Mar. 18, 2022.
Prior Publication US 2023/0296834 A1, Sep. 21, 2023
Int. Cl. G02B 6/122 (2006.01); G02B 6/12 (2006.01); G02B 6/136 (2006.01)
CPC G02B 6/122 (2013.01) [G02B 6/12004 (2013.01); G02B 6/136 (2013.01); G02B 2006/12102 (2013.01); G02B 2006/12114 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A method of fabricating a photonic device, comprising:
forming a layer stack over a substrate, wherein the layer stack includes a lower cladding layer, a core layer disposed over the lower cladding layer, and an upper cladding layer disposed over the core layer; and
patterning the layer stack to form a waveguide for the photonic device;
wherein the waveguide includes the lower cladding layer, the core layer, and the upper cladding layer, wherein the core layer includes a lateral sidewall having a convex profile, and wherein the lower and upper cladding layers include respective lateral surfaces having different surface profiles; and
wherein the patterning the layer stack comprises:
etching the upper cladding layer;
etching the core layer to expose the lateral sidewall and to form a re-entrant surface profile along the lateral sidewall; and
etching the lower cladding layer, wherein the etching the lower cladding layer simultaneously etches a top portion of the core layer, while a bottom portion of the core layer retains the re-entrant surface profile.