Method for fabricating equal height metal pillars of different diameters

摘要

A process to form metal pillars on a flip-chip device. The pillars, along with a layer of solder, will be used to bond die pads on the device to respective substrate pads on a substrate. A photoresist is deposited over the device and a first set of die pads on the device are exposed by forming openings of a first diameter in the photoresist. Pillars of the first diameter are formed by electroplating metal onto the exposed die pads. Then a second photoresist deposited over the first photoresist covers the pillars of the first diameter. Openings of a second diameter are formed in the first and second photoresists to expose a second set of die pads. Pillars of the second diameter are formed by electroplating metal onto the exposed die pads. The photoresists are then removed along with conductive layers on the device used as part of the plating process.

主权项

1. A package comprising:
a flip-chip device having die pads thereon; a substrate having substrate pads thereon that are aligned with respective die pads; a first plurality of metal pillars having a first diameter disposed between a first plurality of the die pads and a first plurality of the substrate pads; a second plurality of metal pillars having a second diameter disposed between a second plurality of the die pads and a second plurality of the substrate pads; and a third plurality of metal pillars having a third diameter disposed between a third plurality of the die pads and a third plurality of the substrate pads; wherein the second diameter is greater than the first diameter, the third diameter is greater than the second diameter, all of the of metal pillars have substantially the same height, and the metal pillars are formed by electroplating metal onto the die pads.