Semiconductor package and manufacturing method thereof

A semiconductor package, comprising:

• photonic dies, each comprising a stack of dielectric layers and optical devices embedded in the stack of dielectric layers, wherein the optical devices in each photonic die comprise:
• a grating coupler;
• a first waveguide, connecting to an end of the grating coupler;
• and
• a first tilted reflector, laterally adjacent to the first waveguide;
• and
• an interposer, lying below and attached with the photonic dies, and comprising a second waveguide and a pair of second tilted reflectors at opposite ends of the second waveguide,
• wherein the first tilted reflector in a first one of the photonic dies and a first one of the second tilted reflectors in the interposer are configured that an optical signal emitted from the first waveguide and deflected by the first tilted reflector in the first one of the photonic dies propagates to the first one of the second tilted reflectors in the interposer and is re-directed to the second waveguide by the first one of the second tilted reflectors, and
• wherein a second one of the second tilted reflectors in the interposer and the first tilted reflector in a second one of the photonic dies are configured that an optical signal emitted from the second waveguide and deflected by the second one of the second tilted reflectors propagates to the first tilted reflector in the second one of the photonic dies, and is re-directed by the first tiled reflector to the first waveguide in the second one of the photonic dies.

A manufacturing method of a semiconductor package, comprising:

• attaching a die stack comprising a photonic die and an electronic die on an interposer, wherein the electronic die is stacked on the photonic die and bonded to the photonic die by a front side, the photonic die comprises a first waveguide and a first tilted reflector laterally adjacent to the first waveguide, the interposer lies below and is attached with the die stack, the interposer comprises a second waveguide and a pair of second tilted reflectors at opposite ends of the second waveguide, lateral optical paths are established along the first and second waveguides, a vertical optical path is established between the first reflector and one of the second tilted reflectors, and a method for forming each of the first tilted reflector and the second tilted reflectors comprises:
• providing a dielectric pattern;
• shaping the dielectric pattern, such that a peripheral portion of the dielectric pattern is shaped to form a staircase structure;
• smoothing out the staircase structure, to form a sloped sidewall at a side of the dielectric pattern;
• forming a reflective layer to cover the dielectric pattern;
• and
• patterning the reflective layer, such that a portion of the reflective layer remains along the sloped sidewall of the dielectric pattern, for forming a tilted reflector as any one of the first and second tilted reflectors.