PTAB

IPR2019-01158

LG Innotek Co Ltd v. Seoul Semiconductor Co Ltd

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Light Emitting Diode Chip Having Wavelength Converting Layer and Method of Fabricating the Same...
  • Brief Description: The ’448 patent relates to a light-emitting diode (LED) chip designed for improved light efficiency. The technology involves a semiconductor stacked structure on a substrate, a wavelength converting layer that covers the chip’s surfaces, and a distributed Bragg reflector (DBR) combined with a metal layer to reflect light and enhance output.

3. Grounds for Unpatentability

Ground 1A: Obviousness over Chang and Reeh - Claims 1-5, 7-14, 18, and 19 are obvious over Chang in view of Reeh.

  • Prior Art Relied Upon: Chang (a Sep. 2008 IEEE journal article) and Reeh (Patent 6,812,500).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Chang taught the core LED structure recited in independent claims 1 and 8. Specifically, Chang disclosed a nitride-based LED with a semiconductor stack on a sapphire substrate and a hybrid backside reflector. This reflector combined a DBR, made of alternately stacked insulating layers (TiO2/SiO2) with different refractive indices, and a metal mirror (Aluminum), satisfying limitations [1.1], [1.2], [1.4], [1.5], and [1.6]. Petitioner contended that Reeh supplied the teaching for the wavelength converting layer (limitation [1.3]). Reeh disclosed applying a luminescence conversion layer, such as YAG:Ce phosphor mixed in a transparent plastic, to cover the surfaces of an LED semiconductor body to convert blue light into white light.
    • Motivation to Combine: A POSITA would combine Reeh’s well-known technique for generating white light with Chang’s high-efficiency LED structure. The motivation was to achieve a high-efficiency white LED, a common and desirable goal in the art. Reeh explicitly taught the benefits of its phosphor layer, including good light mixing, higher luminous efficiency, and high thermal stability, which a POSITA would find desirable to incorporate into the advanced reflector design of Chang.
    • Expectation of Success: The combination involved applying a conventional phosphor encapsulation to a known LED structure, using predictable and well-established techniques, leading to a high expectation of success.

Ground 1B: Obviousness over Chang, Reeh, and Komoto - Claims 3-5, 7, 15-16, and 19 are obvious over Chang-Reeh and Komoto.

  • Prior Art Relied Upon: Chang (a Sep. 2008 IEEE journal article), Reeh (Patent 6,812,500), and Komoto (Patent 6,340,824).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground was asserted as an alternative to Ground 1A. Petitioner argued that to the extent the Chang-Reeh combination was deemed not to teach the first and second insulating layers recited in dependent claims (e.g., claims 3, 4, and 19), Komoto provided this missing element. Komoto disclosed a GaN semiconductor light-emitting element covered by two protective films of silicon oxide, which function as first and second insulating layers disposed on the semiconductor structure.
    • Motivation to Combine: A POSITA would be motivated to add Komoto’s protective insulating layers to the Chang-Reeh LED. The motivation was to gain the known benefits of such layers, including enhanced device performance, stability, and reliability by reducing surface leakage currents and protecting the device from environmental damage.
    • Expectation of Success: Applying protective films was a standard practice in semiconductor manufacturing, and a POSITA would have expected to successfully add these layers to the Chang-Reeh device with predictable results.

Ground 2A: Obviousness over Yoo and Chang - Claims 1-5, 7-12, 14-16, 18, and 19 are obvious over Yoo in view of Chang.

  • Prior Art Relied Upon: Yoo (Application # 2005/0093004) and Chang (a Sep. 2008 IEEE journal article).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner asserted that Yoo, as the primary reference, disclosed a lateral topology blue LED chip. Yoo’s LED included a semiconductor stack on a sapphire substrate, passivation layers, and a thin film of fluorescent material (phosphor) formed over the passivation layer to cover the blue LED element, thereby creating a white LED. This met limitations [1.1], [1.2], and [1.3]. Petitioner argued that Chang supplied the teachings for the hybrid backside reflector (limitations [1.4], [1.5], [1.6]).
    • Motivation to Combine: A POSITA would combine Chang’s hybrid backside reflector with Yoo’s lateral LED to solve the well-known problem of downward light loss toward the substrate. Chang’s DBR and metal mirror would "effectively reflect those photons emitted downward... to enhance the LED output intensity significantly." This combination represented a predictable solution to a known problem to achieve a desired result.
    • Expectation of Success: The integration of a backside reflector was a known technique for improving LED light extraction, and a POSITA would have a high expectation of successfully applying Chang's reflector to Yoo's LED.
  • Additional Grounds: Petitioner asserted Ground 2B, arguing claims 4-5, 7, and 13 are obvious over Yoo-Chang and Komoto. This ground relied on a similar incremental theory as Ground 1B, proposing the substitution of Komoto's protective insulating films for Yoo's passivation layers to obtain predictable benefits of enhanced device protection.

4. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-5, 7-16, 18, and 19 of the ’448 patent as unpatentable.