Underfill materials with graded moduli for semiconductor device assemblies, and associated methods and systems are disclosed. In one embodiment, the underfill material between a semiconductor die and a package substrate includes a matrix material, first filler particles with a first size distribution, and second filler particles with a second size distribution different than the first size distribution. Centrifugal force may be applied to the underfill material to arrange the first and second filler particles such that the underfill material may form a first region having a first elastic modulus and a second region having a second elastic modulus different than the first elastic modulus. Once the underfill material is cured, portions of conductive pillars coupling the semiconductor die with the package substrate may be surrounded by the first region, and conductive pads of the package substrate may be surrounded by the second region.

A fabrication method of an electronic device bonding structure includes the following steps. A first electronic component including a first conductive bonding portion is provided. A second electronic component including a second conductive bonding portion is provided. A first organic polymer layer is formed on the first conductive bonding portion. A second organic polymer layer is formed on the second conductive bonding portion. Bonding is performed on the first electronic component and the second electronic component through the first conductive bonding portion and the second conductive bonding portion, such that the first electronic component and the second electronic component are electrically connected. The first organic polymer layer and the second organic polymer layer diffuse into the first conductive bonding portion and the second conductive bonding portion after the bonding. An electronic device bonding structure is also provided.

A fabrication method of an electronic device bonding structure includes the following steps. A first electronic component including a first conductive bonding portion is provided. A second electronic component including a second conductive bonding portion is provided. A first organic polymer layer is formed on the first conductive bonding portion. A second organic polymer layer is formed on the second conductive bonding portion. Bonding is performed on the first electronic component and the second electronic component through the first conductive bonding portion and the second conductive bonding portion, such that the first electronic component and the second electronic component are electrically connected. The first organic polymer layer and the second organic polymer layer diffuse into the first conductive bonding portion and the second conductive bonding portion after the bonding. An electronic device bonding structure is also provided.

A hybrid bonding structure and a semiconductor including the hybrid bonding structure are provided. The hybrid bonding structure includes a solder ball and a solder paste bonded to the solder ball. The solder paste may include solder particles including at least one of In, Zn, SnBiAg alloy, or SnBi alloy, and ceramic particles. The solder paste may include a flux. The solder particles may include Sn(42.0 wt %)-Ag(0.4 wt %)-Bi(57.5−X) wt %, and the ceramic particles include CeO.sub.2(X) wt %, where 0.05≤X≤0.1.

In one instance, a method of forming a semiconductor package with a leadframe includes cutting, such as with a laser, a first side of a metal strip to a depth D1 according to a cutting pattern to form a first plurality of openings, which may be curvilinear. The method further includes etching the second side of the metal strip to a depth D2 according to a photoresist pattern to form a second plurality of openings. At least some of the first plurality of openings are in fluid communication with at least some of the second plurality of openings to form a plurality of leadframe leads. The depth D1 is shallower than a height H of the metal strip, and the depth D2 is also shallower than the height H. Other embodiments are presented.

A conductive interconnect structure includes a contact pad; a conductive body connected to the contact pad at a first end; and a conductive layer positioned on a second end of the conductive body. The conductive body has a longitudinal direction perpendicular to a surface of the contact pad. The conductive body has an average grain size (a) on a cross sectional plane (Plane A) whose normal is perpendicular to the longitudinal direction of the conductive body. The conductive layer has an average grain size (b) on Plane A. The conductive body and the conductive layer are composed of same material, and the average grain size (a) is greater than the average grain size (b).

A method of making an assembly can include juxtaposing a top surface of a first electrically conductive element at a first surface of a first substrate with a top surface of a second electrically conductive element at a major surface of a second substrate. One of: the top surface of the first conductive element can be recessed below the first surface, or the top surface of the second conductive element can be recessed below the major surface. Electrically conductive nanoparticles can be disposed between the top surfaces of the first and second conductive elements. The conductive nanoparticles can have long dimensions smaller than 100 nanometers. The method can also include elevating a temperature at least at interfaces of the juxtaposed first and second conductive elements to a joining temperature at which the conductive nanoparticles can cause metallurgical joints to form between the juxtaposed first and second conductive elements.

A method of manufacturing a package, comprising embedding the semiconductor chip with an encapsulant comprising a transition metal in a concentration in a range between 10 ppm and 10,000 ppm; selectively converting of a part of the transition metal, such that the electrical conductivity of the encapsulant increases; and plating the converted part of the encapsulant with an electrically conductive material.

Semiconductor device assemblies with solderless interconnects, and associated systems and methods are disclosed. In one embodiment, a semiconductor device assembly includes a first conductive pillar extending from a semiconductor die and a second conductive pillar extending from a substrate. The first conductive pillar may be connected to the second conductive pillar via an intermediary conductive structure formed between the first and second conductive pillars using an electroless plating solution injected therebetween. The first and second conductive pillars and the intermediary conductive structure may include copper as a common primary component, exclusive of an intermetallic compound (IMC) of a soldering process. A first sidewall surface of the first conductive pillar may be misaligned with respect to a corresponding second sidewall surface of the second conductive pillar. Such interconnects formed without IMC may improve electrical and metallurgical characteristics of the interconnects for the semiconductor device assemblies.

Semiconductor device assemblies with solderless interconnects, and associated systems and methods are disclosed. In one embodiment, a semiconductor device assembly includes a first conductive pillar extending from a semiconductor die and a second conductive pillar extending from a substrate. The first conductive pillar may be connected to the second conductive pillar via an intermediary conductive structure formed between the first and second conductive pillars using an electroless plating solution injected therebetween. The first and second conductive pillars and the intermediary conductive structure may include copper as a common primary component, exclusive of an intermetallic compound (IMC) of a soldering process. A first sidewall surface of the first conductive pillar may be misaligned with respect to a corresponding second sidewall surface of the second conductive pillar. Such interconnects formed without IMC may improve electrical and metallurgical characteristics of the interconnects for the semiconductor device assemblies.