PACKAGING OPTICAL COMPONENTS IN A CIRCUIT PACKAGE
The present disclosure relates to example implementations of optically accessible circuit packages. For example, this disclosure includes implementations for creating a circuit package with a photonic integrated circuit (PIC) connected to electrical integrated circuit (EIC) components via an organic interposer. In many implementations, the circuit package maintains optical access to a gating coupler (GC) region on the PIC via an internal cavity area in the organic interposer. In this way, a fiber array unit (FAU) or other optical connection can couple to the circuit package to communicate data from the EIC components of the circuit package and another circuit package or an external device connected to the FAU (e.g., both send and receive data with the cp) via the open access GC region.
1 . A method for packaging a circuit package while preserving optical access to a grating coupler (GC) on a photonic integrated circuit (PIC) of the circuit package, the method comprising:
forming an organic interposer with an internal cavity area;
forming a dam wall on a top surface of the organic interposer that surrounds the internal cavity area, the dam wall creating a raised perimeter around the internal cavity area;
depositing a PIC over the organic interposer with a GC region of the PIC positioned over the internal cavity area of the organic interposer;
applying an underfill material between a portion of the PIC and the organic interposer, wherein the dam wall positioned around the raised perimeter prevents the underfill material from flowing into the internal cavity area; and
solidifying the underfill material such that a seal between the PIC and the organic interposer is created around the internal cavity area of the organic interposer.
2 . The method of claim 1 , further comprising applying a molding compound over the PIC, exposed portions of the underfill material, and exposed portions of the organic interposer, wherein the underfill material clogged by the dam wall prevents the molding compound from entering the internal cavity area.
3 . The method of claim 1 , further comprising:
bonding the organic interposer on a removable mechanical base in connection with forming the organic interposer;
debonding the removable mechanical base to remove the removable mechanical base from the organic interposer; and
attaching an electronic integrated circuit component (EIC component) to the organic interposer, wherein:
the EIC component electronically communicates with the PIC via the organic interposer; and
the EIC component is offset from the internal cavity area of the organic interposer.
4 . The method of claim 3 , further comprising:
inserting a fiber array unit (FAU) into the internal cavity area of the organic interposer; and
attaching the FAU to the GC of the PIC.
5 . The method of claim 4 , wherein attaching the FAU to the GC of the PIC includes aligning fiber ends of the FAU to bidirectional photonic links within the PIC that allow light to enter or exit via GCs within the GC region of the PIC.
6 . The method of claim 5 , wherein the FAU connects the EIC component to an external device via the organic interposer, the PIC, and an optical connection between the FAU and the external device.
7 . The method of claim 1 , wherein:
the organic interposer is formed on a removable mechanical base; and
the removable mechanical base includes a glass carrier.
8 . The method of claim 1 , wherein the organic interposer includes one or more redistribution layers.
9 . The method of claim 1 , wherein forming the organic interposer includes utilizing a lithography process to build layers of material with electrically conductive patterns over a removable mechanical base.
10 . The method of claim 9 , wherein:
forming the dam wall includes causing the lithography process to not place the layers of materials within the internal cavity area of the organic interposer; and
a location of the internal cavity area corresponds to an expected position of the GC when the PIC is deposited over the organic interposer.
11 . The method of claim 1 , wherein:
the internal cavity area is defined by an internal interposer wall from a bottom surface of the organic interposer to a top surface of the dam wall; and
the internal cavity area is void of material.
12 . A method for packaging a photonic circuit while preserving optical access to a grating coupler (GC) on a photonic integrated circuit (PIC) of the photonic circuit, the method comprising:
forming an organic interposer with an internal cavity area;
forming a dam wall on a top surface of the organic interposer that surrounds the internal cavity area, the dam wall creating a raised perimeter around the internal cavity area;
depositing a PIC over the organic interposer with a GC region of the PIC positioned over the internal cavity area of the organic interposer;
applying an underfill material between a portion of the PIC and the organic interposer, wherein a viscosity value of the underfill material causes the underfill material to stop at the dam wall positioned around the raised perimeter and prevents the underfill material from flowing into the internal cavity area; and
solidifying the underfill material such that a seal between the PIC and the organic interposer is created around the internal cavity area of the organic interposer.
13 . The method of claim 12 , wherein the dam wall has a height length that is a same or smaller in length than a width length.
14 . The method of claim 12 , wherein:
the dam wall extends a height of the organic interposer surrounding the internal cavity area; and
the dam wall fully surrounds the internal cavity area.
15 . The method of claim 12 , wherein the dam wall forms the raised perimeter as a rectangular shape or a round shape around the internal cavity area.
16 . The method of claim 12 , wherein the dam wall is created with a same material used to create the organic interposer.
17 . The method of claim 12 , wherein depositing the PIC over the organic interposer includes coupling electrical contacts of the PIC with electrical contacts on a top surface of the organic interposer such that a gap exists between a bottom surface of the PIC and a top surface of the dam wall.
18 . The method of claim 17 , wherein:
a first gap between the bottom surface of the PIC and a top surface of the organic interposer is about 20 microns; and
a second gap between the bottom surface of the PIC and the top surface of the dam wall is about 5 microns.
19 . The method of claim 18 , wherein the underfill material has a viscosity thickness that causes the underfill material to fill the first gap, clog in the second gap without entering in the internal cavity area, and not contact the GC region on the PIC.
20 . A method for packaging a circuit package, the method comprising:
forming an organic interposer over a removable mechanical base using lithography, the organic interposer including an internal cavity area;
forming a dam wall on a top surface of the organic interposer that creates a raised perimeter on the organic interposer around the internal cavity area;
depositing a PIC over the organic interposer with a GC region of the PIC positioned over the internal cavity area of the organic interposer, wherein the PIC attaches to the organic interposer forming:
a first gap between a bottom surface of the PIC and the top surface of the organic interposer; and
a second gap between the bottom surface of the PIC and a top surface of the dam wall that is smaller than the first gap; and
applying an underfill material between the first gap, wherein the dam wall positioned around the raised perimeter prevents the underfill material from flowing through the second gap into the internal cavity area.
21 . The method of claim 20 , further comprising solidifying the underfill material to create a seal between the PIC and the organic interposer excluding the internal cavity area of the organic interposer.
22 . The method of claim 20 , wherein the underfill material, when applied to the organic interposer, clogs between a bottom surface of the PIC and a top surface of the dam wall to prevent the underfill material from entering the internal cavity area within the organic interposer.
23 . The method of claim 20 , wherein the underfill material is epoxy.