Pass-through 3D interconnect for microelectronic dies and associated systems and methods
Pass-through 3D interconnects and microelectronic dies and systems of stacked dies that include such interconnects are disclosed herein. In one embodiment, a system of stacked dies includes a first microelectronic die having a substrate, a metal substrate pad, and a first integrated circuit electrically coupled to the substrate pad. A pass-through 3D interconnect extends between front and back sides of the substrate, including through the substrate pad. The pass-through interconnect is electrically isolated from the substrate pad and electrically coupled to a second integrated circuit of a second microelectronic die attached to the back side of the substrate. In another embodiment, the first integrated circuit is a first memory device and the second integrated circuit is a second memory device, and the system uses the pass-through interconnect as part of an independent communication path to the second memory device.
1. A method of manufacturing a stacked system of microelectronic dies, the method comprising:
forming a substrate pad at a front side of a first microelectronic die;
forming first and second metal traces at the front side, wherein the first trace is connected to the substrate pad;
forming a hole having a sidewall that extends through the substrate pad and the first microelectronic die to a second side of the first microelectronic die opposite the first side;
lining at least a portion of the first trace, the substrate pad, and the sidewall with a dielectric material;
filling the hole with a conductive material to form a pass-through 3D interconnect,
wherein
the conductive material extends outside of the hole at the front side,
the conductive material is separated from each of the substrate pad, the first trace, and the sidewall by the dielectric material, and
the second trace is electrically coupled to the pass-through interconnect and electrically isolated from the first trace and the substrate pad;
aligning a metal contact of a second microelectronic die with the pass-through interconnect at the second side of the first microelectronic die; and
coupling the metal contact of the second die with the pass-through interconnect.
2. The method of claim 1 wherein the substrate pad of the first microelectronic die is electrically coupled with a first integrated circuit carried by the first microelectronic die, and wherein the metal contact is electrically coupled with a second integrated circuit carried by the second die.
3. The method of claim 1 , further comprising:
electrically coupling the substrate pad to a first bond pad of an interposer substrate; and
electrically coupling the pass-through interconnect to a second bond pad of the interposer substrate.
4. A method of manufacturing a pass-through interconnect, the method comprising:
forming a hole at a front-side of a semiconductor substrate that extends through a substrate pad and a portion of the semiconductor substrate underlying the substrate pad, the hole including a sidewall that extends through the substrate pad and the portion of the semiconductor substrate, the substrate pad being in electrical communication with an integrated circuit carried by the semiconductor substrate;
forming a plurality of patterned metal traces at the front-side of the semiconductor substrate, the plurality of metal traces including a metal trace attached to the substrate pad;
at least partially lining a portion of the metal trace, a contact surface of the substrate pad, and a section of the sidewall with a dielectric layer; and
forming a metallic fill layer adjacent the dielectric layer,
wherein
the dielectric layer is disposed between the metallic fill layer and the substrate pad, and
the dielectric layer electrically insulates the metallic fill layer from the metal trace.
5. The method of claim 4 wherein forming the hole further comprises forming the hole through the metal trace and an insulating layer of a redistribution layer attached to the semiconductor substrate, wherein the metal trace lines a portion of the contact surface of the substrate pad, and wherein the dielectric layer is attached to a section of the metal trace adjacent the contact surface.
6. The method of claim 4 wherein at least partially lining the contact surface of the substrate pad and the section of the sidewall with the dielectric layer includes:
depositing the dielectric layer at the front-side of the semiconductor substrate;
forming a mask that covers a portion of the hole and a portion of at least one of the metal trace and the substrate pad; and
removing unmasked portions of the dielectric layer from the front-side of the substrate.
7. The method of claim 4 wherein forming the metallic fill layer includes:
depositing a seed layer at the front-side of the semiconductor substrate;
forming a mask on top of a portion of the seed layer, the mask exposing a portion of the seed layer within the hole and adjacent a portion of at least one of the metal trace and the substrate pad; and
plating the exposed portion of the seed layer with the metallic fill layer.
8. The method of claim 4 further comprising thinning the semiconductor substrate to expose a portion of the metallic fill layer at a back-side surface of the semiconductor substrate.
9. The method of claim 4 wherein:
the metal trace is a first metal trace;
forming a plurality of metal traces includes forming a second metal trace at the first side; and
forming the metallic fill layer includes depositing a conductive fill in the hole and on a portion of the second metal trace.
10. A method of manufacturing a microelectronic workpiece, comprising:
forming a contact pad at a first side of a semiconductor substrate;
forming a trace at the first side and separated from the contact pad;
removing material from the contact pad and a portion of the semiconductor substrate underlying the contact pad to form a hole having a sidewall that extends through both the contact pad and the semiconductor substrate toward a second side of the semiconductor substrate opposite the first side;
depositing a dielectric material such that the dielectric material lines the sidewall, the contact pad, and the trace;
exposing a surface of the trace through a portion of the dielectric material; and
depositing a conductive fill at the first side and within the hole, wherein a portion of the conductive fill is on the exposed surface, and wherein the dielectric material separates the conductive fill from each of the contact pad and the sidewall.
11. The method of claim 10 wherein the contact pad and the trace are electrically coupled to a semiconductor circuit in the semiconductor substrate.
12. The method of claim 10 wherein forming the trace comprises depositing a conductive material on the semiconductor substrate.
13. The method of claim 12 wherein depositing the dielectric material includes depositing the dielectric material on at least a portion of the trace such that the portion of the trace is disposed between the dielectric material and the contact surface.
14. The method of claim 12 wherein the trace is a first trace, and wherein removing material from the contact pad and the portion of the semiconductor substrate further comprises forming the hole through a second trace connected to the contact pad and such that the sidewall also extends through the portion of the second trace.