US 8,410,604 B2Granted

Lead-free structures in a semiconductor device

AssigneeXilinx, Inc.

InventorsLaurene Yip, Leilei Zhang, Kumar Nagarajan

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Abstract

A semiconductor device includes a semiconductor die and a plurality of lead-free solder bumps disposed on a surface of the semiconductor die. A substrate includes a plurality of metal layers and a plurality of dielectric layers. One of the metal layers includes a plurality of contact pads corresponding to the plurality of lead-free solder bumps, and one of the dielectric layers is an exterior dielectric layer having a plurality of respective openings for the contact pad. A plurality of respective copper posts is disposed on the contact pads. The respective copper post for each contact pad extends from the contact pad through the respective opening for the contact pad. The semiconductor die is mounted on the substrate with connections between the plurality of lead-free solder bumps and the plurality of copper posts.

Claims18

Dependent claims

A semiconductor device, comprising:

a semiconductor die;
a plurality of lead-free solder bumps disposed on a surface of the semiconductor die;
a substrate including a plurality of metal layers and a plurality of dielectric layers, wherein one of the plurality of metal layers includes a plurality of contact pads corresponding to the plurality of lead-free solder bumps, and one of the plurality of dielectric layers is an exterior dielectric layer having a plurality of respective openings for the plurality of contact pads;
a plurality of respective copper posts disposed on the plurality of contact pads, wherein the respective copper post for each contact pad extends from the contact pad through the respective opening for the contact pad;
and
wherein:
the semiconductor die is mounted on the substrate with connections between the plurality of lead-free solder bumps and the plurality of copper posts;
the surface of the semiconductor die has a respective silicon metal pad disposed at each of the plurality of lead-free solder bumps;
each lead-free solder bump is reflow soldered to a first area of the respective silicon metal pad and to a second area of the respective copper post;
and
the first and second areas are equal in size and each size exceeds a cross-sectional area through an inner portion of the respective copper post, the inner portion between the contact pad and the second area.

8 more elements

A method of fabricating a semiconductor device, comprising:

forming a semiconductor die having a plurality of lead-free solder bumps for connecting to a substrate;
forming an substrate including an exterior dielectric layer and a plurality of contact pads, the plurality of contact pads exposed through a plurality of respective openings in the exterior dielectric layer;
forming a plurality of respective copper posts on the plurality of contact pads, wherein the respective copper post for each contact pad extends from the contact pad through the respective opening for the contact pad;
aligning the plurality of lead-free solder bumps of the semiconductor die and the plurality of respective copper posts on the plurality of contact pads of the substrate;
and
reflow soldering the plurality of lead-free solder bumps to the plurality of respective copper posts;
wherein:
the forming of the semiconductor die includes forming the semiconductor die having a plurality of respective silicon metal pads at the plurality of lead-free solder bumps;
and
the reflow soldering includes reflow soldering each lead-free solder bump to a first area of the respective silicon metal pad and to a second area of the respective copper post, the first and second areas being equal in size and each size exceeding a cross-sectional area through the portion of the respective copper post between the contact pad and the end cap.

7 more elements

Dependencies are inferred from the claim text.