Samsung Austin Semiconductor LLC v. W&Wsens Devices Inc

1. Case Identification

• Case #: PGR2025-00082
• Patent #: 12,243,948
• Filed: August 28, 2025
• Petitioner(s): Samsung Electronics Co., Ltd., Samsung Electronics America, Inc., Samsung Semiconductor, Inc., and Samsung Austin Semiconductor LLC
• Patent Owner(s): W&WSENS DEVICES INC.
• Challenged Claims: 1-16

2. Patent Overview

• Title: Microstructure-Enhanced Photodetectors
• Brief Description: The ’948 patent relates to photodetectors that employ microstructures to enhance light absorption. The claims recite an integrated structure with an array of pillars containing photodiodes with elongated holes, ranging from 100 to 10,000 nanometers in depth, that increase light absorption by at least 10% compared to photodetectors lacking such features.

3. Grounds for Unpatentability

Ground 1: Claims 1-3 and 7-12 are obvious over Kuboi

• Prior Art Relied Upon: Kuboi (Application # 2012/0049044).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Kuboi, which was not considered during prosecution, discloses all limitations of these claims. Kuboi teaches a CMOS solid-state imaging device with a two-dimensional array of pixels (the claimed "pillars") on a silicon substrate. These pillars function as photodetectors, comprising P-doped (p+-type region 18) and N-doped (n+-type region 17) regions that generate charge carriers upon illumination. Critically, Kuboi discloses fabricating vertical holes ("so-called...trench[es]") that are elongated in a stripe shape, extend into the pillars to a depth of 1400 nm (within the claimed 100-10,000 nm range), and are filled with solid dielectric materials (an electron blocking film and an organic photoelectric conversion film). Kuboi's structure also includes solid material for side-isolation between pillars (element separation region 15) and monolithic integration with Si electronic devices on a single substrate, mapping to limitations in dependent claims.
  • Key Aspects: Petitioner emphasized that Kuboi discloses the very "elongated holes" limitation that Patent Owner added to overcome prior art during prosecution. Petitioner also provided a detailed technical analysis, based on the known absorption coefficients of materials disclosed in Kuboi, to argue that Kuboi’s structure inherently meets the functional limitation of increasing light absorption by at least 1.1x compared to a like photodetector without holes.

Ground 2: Claims 4-6 and 13-16 are obvious over Kuboi in view of Vasylyev

• Prior Art Relied Upon: Kuboi (Application # 2012/0049044) and Vasylyev (Application # 2012/0012741).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground addressed claims requiring pillars with "only one" elongated hole (claims 4 and 14) or holes extending "less than the widths" of the light-receiving surfaces with a "closed contour" (claims 5, 6, and 13d(1)). Kuboi’s primary embodiment discloses multiple trench-like holes per pixel that span the full pixel width. Vasylyev teaches a light harvesting system for photodetectors that uses a single light input port (e.g., a hole or trench) for each microlens to reduce Fresnel reflection and improve light trapping efficiency. Petitioner argued for modifying Kuboi’s blue pixel, which is formed of solid silicon and suffers from high reflection, by incorporating Vasylyev’s single, elongated light input port. This modification would result in a pillar with only one elongated hole having a closed contour, as required by the claims.
  • Motivation to Combine: A POSITA would combine Vasylyev’s teachings with Kuboi to solve the known problem of high Fresnel reflection on silicon photodetectors, a problem particularly acute for the blue light detected by Kuboi’s blue pixels. Vasylyev explicitly teaches using a single input port per lens to improve light coupling and absorption. A POSITA would also be motivated to modify the holes in Kuboi's green and red pixels to extend over a substantial portion, rather than the full width, of the pixel surface—as taught by Vasylyev—to increase the silicon-film interface area and improve device operating speed, a goal explicitly stated in Kuboi.
  • Expectation of Success: Petitioner asserted a high expectation of success because the combination involves applying a known technique (Vasylyev's single port) to a known device (Kuboi's pixel) to achieve a predictable result (reduced reflection and improved absorption). The fabrication methods (dry etching) are compatible and disclosed in both references.

Ground 3: Claims 1-16 lack enablement under §112

• Core Argument for this Ground: Petitioner presented three primary arguments for lack of enablement under 35 U.S.C. §112.

  • First, in a contingent argument, Petitioner asserted that if the Board finds the prior art evidence insufficient to establish the claimed "1.1 factor" increase in light absorption, then the '948 patent’s own disclosure, which relies on the same scientific principles (e.g., High Contrast Grating effects), must also be insufficient to enable a POSITA to achieve that functional limitation without undue experimentation.
  • Second, the patent does not enable the full scope of claims covering single-hole structures (as recited in claims 1, 4, 13, and 14). Its only disclosed scientific basis for enhanced absorption—the High Contrast Grating (HCG) effect—requires a periodic array of multiple holes to function, a condition that is absent in a single-hole embodiment.
  • Third, the patent fails to enable the full scope of claims covering millimeter-sized pillars. Petitioner pointed to the prosecution of a related pending application (the '948 Divisional), where the Examiner rejected similar claims for lack of enablement, stating that the specification "specifically centers the pillar dimensions at around 100 micrometers and micrometers in general" and provides no guidance for achieving the claimed optical effects at a millimeter scale.

• Additional Grounds: Petitioner asserted additional obviousness challenges over Kuboi in view of Shinohara (Application # 2012/0033119) for its teachings on monolithic integration, and over the three-way combination of Kuboi, Vasylyev, and Shinohara.

4. Relief Requested

• Petitioner requested institution of Post-Grant Review and cancellation of claims 1-16 of the '948 patent as unpatentable.