PTAB

IPR2017-00843

Xilinx Inc v. Godo Kaisha IP Bridge 1

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Semiconductor Device, Manufacturing Method and Apparatus for the Same
  • Brief Description: The ’915 patent relates to flip-chip semiconductor packaging technology. It discloses an electrode structure comprising a solder bump, an under-bump metallization (UBM) layer, and a specific intermetallic compound formed at their interface, which purportedly improves reliability by suppressing the dissolution and diffusion of the UBM layer into the solder during the manufacturing process.

3. Grounds for Unpatentability

Ground 1: Claims 1, 2, 6, 8, and 61 are anticipated under 35 U.S.C. § 102 by Kawashima.

  • Prior Art Relied Upon: Kawashima (Patent 6,669,077).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Kawashima, which was not considered during prosecution, discloses every limitation of the challenged claims. Kawashima describes a solder joint for a semiconductor device comprising a multi-layer structure: a wiring layer (copper wire), an under-bump layer (nickel layer 2), an intermetallic compound layer (layer 3), and a solder bump (solder layer 4). Petitioner contended that this structure directly maps to the elements of independent claims 1 and 61.
    • Petitioner asserted that Kawashima’s solder bump is a tin-silver-copper alloy with tin as the "main component." Its under-bump layer is nickel. The resulting intermetallic compound is disclosed as being composed of tin, copper, and nickel. This meets the core limitation of claim 1, which requires an intermetallic compound including a metal that is the main component of the solder (tin) and a second metal (copper) that is different from both the solder’s main component (tin) and the metal of the adjoining under-bump layer (nickel).
    • For the dependent claims, Petitioner argued Kawashima expressly discloses that tin is the main component of the alloy solder (claim 2), the second metal (copper) is different from the first metal of the under-bump layer (nickel) (claim 6), and the under-bump layer includes nickel (claim 8).

Ground 2: Claims 1, 2, 6, 8, and 61 are anticipated under 35 U.S.C. § 102 by Liu.

  • Prior Art Relied Upon: Liu et al., Electron microscopy study of interfacial reaction between eutectic and Cu/Ni(V)/Al thin film metallization (J. Applied Physics, Jan. 2000).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Liu, a pre-critical date journal article, also anticipates all challenged claims by disclosing a functionally identical flip-chip structure. Liu describes an electrode structure with a eutectic tin-lead (SnPb) solder bump on a UBM stack that includes a nickel-vanadium (Ni(V)) layer over an aluminum wiring layer. Petitioner asserted that after a reflow process, Liu’s analysis shows the formation of copper-tin intermetallic compounds (Cu6Sn5 and Cu3Sn) at the interface between the solder and the Ni(V) layer.
    • Petitioner contended this disclosed structure meets every limitation of claim 1. The main component of Liu's eutectic solder is tin. The adjoining under-bump layer is nickel-vanadium. The intermetallic compound that forms contains tin (the main component) and copper (the second metal). This second metal (copper) is different from the solder's main component (tin) and also different from the metal of the adjoining under-bump layer (nickel-vanadium).
    • As with the Kawashima ground, Petitioner argued that Liu’s disclosure inherently meets the limitations of the dependent claims by teaching a solder where tin is the main component (claim 2), a second metal (copper) different from the first metal (nickel-vanadium) (claim 6), and an under-bump layer that includes nickel (claim 8).

4. Key Claim Construction Positions

  • "solder bump": Petitioner proposed this term be construed to mean "solder material after a reflow process has been performed." This construction distinguishes the final structure from the pre-reflow "solder ball" also mentioned in the ’915 patent specification.
  • "under-bump layer": Petitioner argued for the plain and ordinary meaning: "a metal layer disposed between a solder bump and a wiring layer," consistent with its structural role described in the specification.
  • "intermetallic compound": Petitioner proposed the plain meaning of "an alloy layer comprising two or more metals between adjoining metal layers." This construction was central to mapping the prior art, which describes such alloy layers forming at the interface.
  • "main component of the alloy solder": Petitioner argued this term means "the element of the alloy solder that is present in the alloy solder in the highest weight percentage." This was based on examples in the ’915 patent where tin, at 96.5 weight %, was identified as the main component.

5. Relief Requested

  • Petitioner requests institution of IPR and cancellation of claims 1, 2, 6, 8, and 61 of the ’915 patent as unpatentable.