Self-aligned buried hetero structure laser structures and interposer

A method for forming a die comprising a buried heterostructure laser structure, the method comprising

• forming a first stack of layers on a substrate,
• wherein the first stack of layers comprises a quantum well layer configured to generate an optical signal;
• patterning the first stack of layers,
• wherein the patterning the first stack of layers comprises forming a ridge component of the buried heterostructure laser structure;
• wherein the patterning the first stack of layers further comprises forming one or more first side surfaces of a first alignment feature,
• wherein the one or more first side surfaces are configured restrict movements of the die in directions perpendicular to a propagation direction of the optical signal by the one or more first side surfaces disposed in a close proximity of one or more second side surfaces of an interposer when the die is mounted on the interposer;
• forming a current blocking layer at least at the sidewalls of the ridge component;
• forming a second stack of layers;
• patterning the second stack of layers and the current blocking layer;
• removing the first stack of layers on a portion of the substrate to form one or more exposed surfaces of a second alignment feature,
• wherein the one or more exposed surfaces are configured to contact a top surface of an interposer, with a first distance between the exposed portion and the optical signal being substantially the same as a second distance between the top surface and an optical pathway on the interposer.

A method for forming an assembly comprising a die mounted on an interposer, the method comprising

• forming the die, with the die comprising a buried heterostructure laser structure fabricated on a substrate, the forming the die comprising
• forming a first stack of layers on a substrate,
• wherein the first stack of layers comprises a quantum well layer configured to generate an optical signal;
• patterning the first stack of layers,
• wherein the patterning the first stack of layers comprises forming a ridge component of the buried heterostructure laser structure;
• wherein the patterning the first stack of layers further comprises forming one or more first side surfaces of a first alignment feature,
• forming a current blocking layer at least at the sidewalls of the ridge component;
• forming a second stack of layers;
• patterning the second stack of layers and the current blocking layer;
• removing the first stack of layers on a portion of the substrate to expose a portion of the substrate comprising a first distance between the exposed portion and the optical signal,
• forming first contacts for the heterostructure laser structure,
• forming the interposer, the forming the interposer comprising
• forming an optical device comprising an optical pathway on a substrate,
• forming a cavity recessed from a top surface of the substrate, with the cavity configured for mounting the die within the cavity, and with the cavity exposing the optical pathway,
• wherein the optical pathway is spaced from the top surface by a second distance,
• wherein the first distance between the exposed portion and the optical signal is substantially the same as the second distance between the top surface and an optical pathway,
• forming one or more second side surfaces in the cavity,
• forming second contacts,
• wherein the forming the second contacts comprises misaligning the first and second contacts when the die is placed in the cavity of the interposer,
• coupling the die to the interposer, the coupling the die to the interposer comprising
• placing the die in the cavity of the interposer,
• wherein the placing the die in the cavity comprises contacting the exposed portion of the substrate with the top surface of the interposer for aligning the optical signal with the optical path in a direction perpendicular to the top surface of the interposer,
• wherein the placing the die in the cavity comprises disposing the one or more first side surfaces-in a close proximity of the one or more second side surfaces of an interposer to restrict movements of the die in directions perpendicular to a propagation direction of the optical signal,
• wherein the placing the die in the cavity comprises contacting the first contacts with the second contacts,
• heating the first and second contacts,
• wherein the heating the first and second contacts realigns the first and second contacts by moving the die toward the optical pathway with the one or more second side surfaces guiding the die movement to obtain a desired offset of the optical signal in the direction perpendicular to a propagation direction of the optical signal.