Photonic-integrated-circuit fabrication process

Claim 1

A method of fabricating at least one photonic integrated circuit comprising epitaxially growing a stack of numerous layers of semiconductor materials, at least two of which differ in either material composition or doping level or doping type, at least a portion of each of the material layers serving a function in at least one of the devices which will comprise the photonic integrated circuit or in at least one of the photonic integrated circuit fabrication steps, THE INVENTION CHARACTERIZED IN THAT (1) the stack is selectively etched to define areas of specific layer combinations, at least a portion of some of such areas ultimately forming devices which will comprise the photonic integrated circuit, the specific layer combination of each such areas being appropriate for each of such devices, (2) a first, stripe geometry, mask is subsequently deposited to protect the region of the remaining stack underlying the mask from subsequent etching, (3) unmasked portions of the stack are subsequently etched, (4) a second mask, at least a portion of which overlies the first mask, and at least a portion of the overlying region of said overlying mask having a width larger than that of the first, stripe geometry, mask, is subsequently deposited to protect the region of the remaining stack underlying either the first or second mask from subsequent etching, (5) unmasked portions of the stack are subsequently etched, whereby portions of the stack which underlie only the second mask are less deeply etched than portions of the stack which do not underlie either of the masks, and a stripe geometry mesa is thereby formed with regions of deep and shallow sidewalls, (6) growing additional epitaxial materials which serve as current blocking layers in regions adjacent to those regions which ultimately form devices to which electric fields are applied, and said same additional epitaxial materials serve as cladding layers in regions which ultimately form optical waveguides.

Claim 2

A method of fabricating at least one photonic integrated circuit comprising epitaxially growing a stack of numerous layers of semiconductor materials, at least two of which differ in either material composition or doping level or doping type, at least a portion of each of the material layers serving a function in at least one of the devices which will comprise the photonic integrated circuit or in at least one of the photonic integrated circuit fabrication steps, THE INVENTION CHARACTERIZED IN THAT (1) the stack is selectively etched to define areas of specific layer combinations, at least a portion of some of such areas ultimately forming devices which will comprise the photonic integrated circuit, the specific layer combination of each such areas being appropriate for each of such devices, (2) a first, stripe geometry, mask is subsequently deposited to protect the region of the remaining stack underlying the mask from subsequent etching, (3) unmasked portions of the stack are subsequently etched, (4) a second mask, at least a portion of which overlies the first mask, and at least a portion of the overlying region of said overlying mask having a width larger than that of the first, stripe geometry, mask, is subsequently deposited to protect the region of the remaining stack underlying either the first or second mask from subsequent etching, (5) unmasked portions of the stack are subsequently etched, whereby portions of the stack which underlie only the second mask are less deeply etched than portions of the stack which do not underlie either of the masks, and a stripe geometry mesa is thereby formed with regions of deep and shallow sidewalls, (6) growing additional epitaxial materials which serve as current blocking layers in regions adjacent to those regions which ultimately form devices to which electric fields are applied, and said same additional epitaxial materials serve as cladding layers in regions which ultimately form optical waveguides.