A microelectronic unit may include an epitaxial silicon layer having a source and a drain, a buried oxide layer beneath the epitaxial silicon layer, an ohmic contact extending through the buried oxide layer, a dielectric layer beneath the buried oxide layer, and a conductive element extending through the dielectric layer. The source and the drain may be doped portions of the epitaxial silicon layer. The ohmic contact may be coupled to a lower surface of one of the source or the drain. The conductive element may be coupled to a lower surface of the ohmic contact. A portion of the conductive element may be exposed at the second dielectric surface of the dielectric layer. The second dielectric surface may be directly bonded to an external component to form a microelectronic assembly.

A microelectronic unit may include an epitaxial silicon layer having a source and a drain, a buried oxide layer beneath the epitaxial silicon layer, an ohmic contact extending through the buried oxide layer, a dielectric layer beneath the buried oxide layer, and a conductive element extending through the dielectric layer. The source and the drain may be doped portions of the epitaxial silicon layer. The ohmic contact may be coupled to a lower surface of one of the source or the drain. The conductive element may be coupled to a lower surface of the ohmic contact. A portion of the conductive element may be exposed at the second dielectric surface of the dielectric layer. The second dielectric surface may be directly bonded to an external component to form a microelectronic assembly.

Implementations of a semiconductor package may include a die; a first pad and a second pad, the first pad and the second pad each including a first layer and a second layer where the second layer may be thicker than the first layer. At least a first conductor may be directly coupled to the second layer of the first pad; at least a second conductor may be directly coupled to the second layer of the second pad; and an organic material may cover at least the first side of the die. The at least first conductor and the at least second conductor extend through openings in the organic material where a spacing between the at least first conductor and the at least second conductor may be wider than a spacing between the second layer of the first pad and the second layer of the second pad.

In some examples, a package comprises a die and a redistribution layer coupled to the die. The redistribution layer comprises a metal layer, a brass layer abutting the metal layer, and a polymer layer abutting the brass layer.

A flip chip includes a substrate, an electrode pad layer stacked over the substrate, a passivation layer stacked at both ends of the electrode pad layer, an under bump metallurgy (UBM) layer stacked over the electrode pad layer and the passivation layer, and a bump formed over the UBM layer. The width of an opening on which the passivation layer is not formed over the electrode pad layer is greater than the width of the bump. The flip chip can prevent a crack from being generated in the pad upon ultrasonic bonding.

A pad is disposed on a substrate. A bump structure is disposed on the pad and electrically connected to the pad. The bump structure includes a first copper layer and a second copper layer sequentially stacked on the pad and a solder ball on the second copper layer. A first X-ray diffraction (XRD) peak intensity ratio of (111) plane to (200) plane of the first copper layer is greater than a second XRD peak intensity ratio of (111) plane to (200) plane of the second copper layer.

Various semiconductor chips and packages are disclosed. In one aspect, an apparatus is provided that includes a semiconductor chip that has a side, and plural conductive pillars on the side. Each of the conductive pillars includes a pillar portion that has an exposed shoulder facing away from the semiconductor chip. The shoulder provides a wetting surface to attract melted solder. The pillar portion has a first lateral dimension at the shoulder. A solder cap is positioned on the pillar portion. The solder cap has a second lateral dimension smaller than the first lateral dimension.

A semiconductor package may include a substrate and a semiconductor chip on the substrate. The substrate may include an inner insulating layer, a redistribution layer in the inner insulating layer, an outer insulating layer on the inner insulating layer, a connection pad provided in the outer insulating layer and electrically connected to the redistribution layer, and a ground electrode in the outer insulating layer. A top surface of the connection pad may be exposed by a top surface of the outer insulating layer, and a level of the top surface of the connection pad may be lower than a level of the top surface of the outer insulating layer. A level of a bottom surface of the ground electrode may be higher than a level of a top surface of the redistribution layer, and the outer insulating layer covers a top surface of the ground electrode.

A method is provided. The method includes one or more of conditioning one or more die pads of a singular die, applying a nickel layer to the one or more die pads, applying a gold layer over the nickel layer, applying a solder paste over the gold layer, applying one or more solder balls to the solder paste, and mating the one or more solder balls to one or more bond pads of another die, a printed circuit board, or a substrate.

The subject matter contained herein discloses methods for forming a vertical metallic pillar overlying an under bump metal pad further overlying a semiconductor substrate, and applying a discrete solder cap on a top surface of the pillar, wherein the metallic pillar is defined by at least one photoresist layer. The method includes heating a multi-element metallic paste containing a variable amount of metallic powder, a melting point depressant and a flux such that the metal powder sinters to form the metallic pillar and simultaneously adheres the metallic pillar to the underbump metal pad.