International Business Machines Corporation

US Government As Represented by the Secretary of the Army

Stephen James Kilpatrick

Henry Atkinson Nye, Iii

Da-Yuan Shih

Donna S Zupanski-Nielsen

Keith E Fogel

Paul Alfred Lauro

Sung Kwon Kang

Balaram Ghosal

Emanuel Israel Cooper

Charles C Goldsmith

Carmen M Mojica

John Michael Cotte

Carlos Juan Sambucetti

David Hirsch Danovitch

Donald W Henderson

Yu-Ting Cheng

Ronald G Polcawich

Stefanie Ruth Chiras

Lisa A Fanti

David E Eichstadt

James H Wilson

Osama M Nayfeh

Sung-Kwon Kang

Emanual I Cooper

Madam Dubey

A voltage controlled oscillator comprising a substrate and a bilayer graphene transistor formed on the substrate. The transistor has two signal terminals and a gate terminal positioned in between the signal terminals. A voltage controlled PZT or MEMS capacitor is also formed on the substrate. The capacitor is electrically connected to the transistor gate terminal. At least one component is connected to the transistor and capacitor to form a resonant circuit.

Voltage tunable oscillator using bilayer graphene and a lead zirconate titanate capacitor

An interconnection structure suitable for flip-chip attachment of microelectronic device chips to packages, comprising a two, three or four layer ball-limiting composition including an adhesion/reaction barrier layer, and having a solder wettable layer reactive with components of a tin-containing lead free solder, so that the solderable layer can be totally consumed during soldering, but a barrier layer remains after being placed in contact with the lead free solder during soldering. One or more lead-free solder balls is selectively situated on the solder wetting layer, the lead-free solder balls comprising tin as a predominant component and one or more alloying components. With a two-layer ball-limiting composition comprising an adhesion/reaction barrier layer, wherein the adhesion/reaction barrier layer serves both as an adhesion layer and a reaction barrier layer, the adhesion/reaction barrier layer can be comprised of a material selected from the group consisting of Zr and ZrN.

Interconnections for flip-chip using lead-free solders and having reaction barrier layers

An interconnection structure suitable for flip-chip attachment of microelectronic device chips to packages, comprising a two, three or four layer ball-limiting composition including an adhesion/reaction barrier layer, and having a solder wettable layer reactive with components of a tin-containing lead free solder, so that the solderable layer can be totally consumed during soldering, but a barrier layer remains after being placed in contact with the lead free solder during soldering. One or more lead-free solder balls is selectively situated on the solder wetting layer, the lead-free solder balls comprising tin as a predominant component and one or more alloying components.

A first metal is plated onto a substrate comprising a second metal by immersing the substrate into a bath comprising a compound of the first metal and an organic diluent. The second metal is more electropositive than the first metal. The organic diluent has a boiling point higher than a eutectic point in a phase diagram of the first and second metals. The bath is operated above the eutectic point but below the melting point of the second metal. For example, bismuth is immersion plated onto lead-free tin-based solder balls, and subsequently redistributed by fluxless reflow. Plated structures are also provided.

Immersion plating and plated structures

A ball-limiting metallurgy includes a substrate, a barrier layer formed over the substrate, an adhesion layer formed over the barrier layer, a first solderable layer formed over the adhesion layer, a diffusion barrier layer formed over the adhesion layer, and a second solderable layer formed over the diffusion barrier layer.

Ball limiting metallurgy, interconnection structure including the same, and method of forming an interconnection structure

A method is provided for removing exposed seed layers in the fabrication of solder interconnects on electronic components such as semiconductor wafers without damaging the interconnects or underlying wafer substrate and with a high wafer yield. The solder interconnects are lead free or substantially lead free and typically contain Sn. An oxalic acid solution is used to contact the wafer after an etching step to remove part of the seed layer. The seed layer is typically a Cu containing layer with a lower barrier layer containing barrier metals such as Ti, Ta and W. The lower barrier layer remains after the etch and the oxalic acid solution inhibits the formation of Sn compounds on the barrier layer surface which compounds may mask the barrier layer and the barrier layer etchant resulting in incomplete barrier layer removal on the wafer surface. Any residual conductive barrier layer can cause shorts and other wafer problems and result in a lower wafer yield. An electroetch is preferred to remove the portion of the seed layer overlying the lower barrier layer.

Inhibition of tin oxide formation in lead free interconnect formation

A method to effectively deposit multi-component solders while remaining compatible with electroplating solder bumping process. A flip-chip solder bump is formed by using electroplated solder bump technology with the addition of wettable layer of metal or solder. The remainder of the required solder volume is deposited by Injection Molded Solder (IMS) technology. This method will accommodate certain metals, as well as trace amounts of alloying, that would be difficult or impossible to electroplate. The method also allows for electrical test between deposition of the wettable layer of solder and the bulk solder, providing the advantages of a more planar surface for probe contact, with very consistent height, less solder pick-up by the test probe and elimination of the post-probe solder reflow step.

Dual-solder flip-chip solder bump

Growing community of inventors

Olney, MD, United States of America

Stephen James Kilpatrick