Integrated circuit package and method of forming same

A package comprising:

• a package component;
• and
• a fiber array unit attached to a first sidewall of the package component, wherein the package component comprises:
• a redistribution structure;
• an optical die bonded to the redistribution structure, the optical die comprising an edge coupler, wherein a first sidewall of the optical die and the first sidewall of the package component are proximate to the edge coupler;
• an optical glue in physical contact with the first sidewall of the optical die and between the edge coupler and the fiber array unit;
• a dam structure on the redistribution structure adjacent to the first sidewall of the optical die in a plan view, wherein an upper surface of the dam structure contacts the optical glue;
• and
• a first underfill between the optical die and the redistribution structure, the first underfill being in physical contact with the dam structure and the optical glue, the first underfill not extending between the edge coupler and the optical glue.

A method comprising:

• forming a dam structure on a redistribution structure;
• bonding an optical die to the redistribution structure, the optical die comprising an edge coupler proximate to a first sidewall of the optical die, the edge coupler being oriented along an optical line, the optical line intersecting the dam structure in a plan view;
• depositing a first underfill between the optical die and the redistribution structure, wherein the first underfill contacts the dam structure;
• forming an optical glue over the dam structure, wherein the optical glue contacts the first sidewall of the optical die along the optical line;
• bonding the redistribution structure to a first substrate, the first substrate having a trench;
• and
• depositing a second underfill between the redistribution structure and the first substrate, wherein the second underfill extends into the trench.