The known electrolytic plating method is disadvantageous in that it is difficult to form thin pillars without being influenced by undercuts. The electroless plating method is disadvantageous in that it is difficult to form pillars in the same shape without voids. As a solution to these, the electrically conductive paste according to the present invention for forming pillars is used to make pillars by filling. This helps prevent undercuts, and it is also intended to provide metal pillars in the same shape with good reproducibility. The inventors found that an electrically conductive paste that is very small fine metal particles and contains a particular percentage of fine metal particles is extraordinarily advantageous in forming pillars.

The known electrolytic plating method is disadvantageous in that it is difficult to form thin pillars without being influenced by undercuts. The electroless plating method is disadvantageous in that it is difficult to form pillars in the same shape without voids. As a solution to these, the electrically conductive paste according to the present invention for forming pillars is used to make pillars by filling. This helps prevent undercuts, and it is also intended to provide metal pillars in the same shape with good reproducibility. The inventors found that an electrically conductive paste that is very small fine metal particles and contains a particular percentage of fine metal particles is extraordinarily advantageous in forming pillars.

A method for fabricating semiconductor die with die-attach preforms is disclosed. In embodiments, the method includes: applying an uncured die-attach paste material to a surface of a forming substrate to form one or more die-attach preforms, the surface of the forming substrate formed from a hydrophobic material; curing the one or more die-attach preforms; performing one or more planarization processes on the one or more die-attach preforms; coupling a first surface of a semiconductor die to a handling tool; and bonding a second surface of the semiconductor die to at least one die-attach preform of the one or more die-attach preforms.

An assembly includes at least one first element comprising at least one first electrical bonding pad; at least one second element comprising at least one second electrical bonding pad; electrical and mechanical interconnect means, wherein the electrical and mechanical interconnect means comprise at least: at least one first intermediate metal interconnect element, on the surface of at least the first electrical bonding pad; at least one sintered joint of metal microparticles or nanoparticles stacked with the first intermediate metal interconnect element; the melting point of the first intermediate metal interconnect element being greater than the sintering temperature of the metal microparticles or nanoparticles. A method for fabricating an assembly is also provided.

A microelectronic device has bump bond structures on input/output (I/O) pads. The bump bond structures include copper-containing pillars, a barrier layer including cobalt and zinc on the copper-containing pillars, and tin-containing solder on the barrier layer. The barrier layer includes 0.1 weight percent to 50 weight percent cobalt and an amount of zinc equivalent to a layer of pure zinc 0.05 microns to 0.5 microns thick. A lead frame has a copper-containing member with a similar barrier layer in an area for a solder joint. Methods of forming the microelectronic device are disclosed.

A microelectronic device has bump bond structures on input/output (I/O) pads. The bump bond structures include copper-containing pillars, a barrier layer including cobalt and zinc on the copper-containing pillars, and tin-containing solder on the barrier layer. The barrier layer includes 0.1 weight percent to 50 weight percent cobalt and an amount of zinc equivalent to a layer of pure zinc 0.05 microns to 0.5 microns thick. A lead frame has a copper-containing member with a similar barrier layer in an area for a solder joint. Methods of forming the microelectronic device are disclosed.

A technique for fabricating a bump structure is disclosed. A substrate that includes a set of pads formed on a surface thereof is prepared, in which the pads includes first conductive material. A metallic adhesion layer is coated on each pad. A bump base is formed on each pad by sintering conductive particles using a mold layer, in which the conductive particles includes second conductive material different from the first conductive material.

A technique for fabricating a bump structure is disclosed. A substrate that includes a set of pads formed on a surface thereof is prepared, in which the pads includes first conductive material. A metallic adhesion layer is coated on each pad. A bump base is formed on each pad by sintering conductive particles using a mold layer, in which the conductive particles includes second conductive material different from the first conductive material.

A method of the present invention includes preparing a substrate having a surface on which a electrode pad is formed, forming a resist layer on the substrate, the resist layer having an opening on the electrode pad, filling conductive paste in the opening of the resist layer; sintering the conductive paste in the opening to form a conductive layer which covers a side wall of the resist layer and a surface of the electrode pad in the opening, a space on the conductive layer leading to the upper end of the opening being formed, filling solder in the space on the conductive layer and removing the resist layer.

Embodiments relate to using flux or underfill as a trapping layer for temporarily attaching light emitting diodes (LEDs) to a substrate and heating to simultaneously bond multiple LEDs onto the substrate. The flux or underfill may be selectively coated at the ends of electrodes of the LEDs prior to placing the LEDs on the substrate. Due to adhesive properties of the flux or underfill, multiple LEDs can be placed on and attached to the substrate prior to performing the bonding process. Once LEDs are placed on the substrate, the flux or underfill facilitates formation of metallic contacts between electrodes of the LED and contacts of the substrate during the bonding process. By using the flux or underfill, the formation of metallic contacts can be performed even without applying pressure.