Micron Technology Inc v. Yangtze Memory Technologies Co Ltd

1. Case Identification

• Case #: PGR2025-00021
• Patent #: 12,010,838
• Filed: January 6, 2025
• Petitioner(s): Micron Technology, Inc.
• Patent Owner(s): Yangtze Memory Technologies Company, Ltd.
• Challenged Claims: 1, 3-7, 12-20

2. Patent Overview

• Title: Staircase Structure for Memory Device
• Brief Description: The ’838 patent discloses 3D NAND memory devices featuring a staircase structure for electrical interconnection. The invention is directed to a specific landing pad configuration where the pad’s first side surface is in contact with an adjacent insulating layer, and its second side surface is laterally displaced from the side of the underlying conductive layer on which it sits.

3. Grounds for Unpatentability

Ground 1: Claims 1, 4-7, 12-17, and 19-20 are obvious over Kim

• Prior Art Relied Upon: Kim (Patent 10,229,929).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Kim, a single prior art reference, discloses every limitation of the challenged independent claims. Kim teaches a 3D memory device with a staircase structure formed from alternating insulating layers ("first material layer") and conductive gate electrodes ("second material layer"). Petitioner asserted that Kim’s "protrusion pad PAD_P" is the claimed "landing pad," which sits atop a base pad at the end of the gate electrode. The protrusion pad is formed within an opening of an auxiliary insulating layer, placing its first side surface in "contact" with that insulating layer. Critically, Kim teaches that its protrusion pad may be formed "inside and spaced apart from the edges" of the underlying base pad, which results in its second side surface being "laterally displaced" (inwardly) from the side surface of the underlying conductive layer.
  • Motivation to Combine (for 35 U.S.C. §103 grounds): As this ground is based on a single reference, Petitioner argued that a person of ordinary skill in the art (POSITA) would have recognized that Kim’s disclosure renders the claims obvious without modification.
  • Expectation of Success (for §103 grounds): A POSITA would have an expectation of success as Kim explicitly teaches all claimed structural elements.

Ground 2: Claims 3 and 18 are obvious over Kim in view of Yang

• Prior Art Relied Upon: Kim (Patent 10,229,929), Yang (Patent 9,941,153).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground addresses dependent claims 3 and 18, which require the lateral displacement of the landing pad to be between 10 nm and 300 nm. While Kim taught the laterally displaced structure, it did not provide specific dimensions. Petitioner asserted that Yang, which discloses a structurally analogous 3D memory device with inset landing pads, provides exemplary dimensions to solve the same manufacturing problems as Kim (e.g., avoiding over-etching). Yang teaches a pad setback, or lateral displacement, in the range of 20-190 nm, which falls squarely within the claimed range.
  • Motivation to Combine (for §103 grounds): A POSITA, seeking to implement Kim's design, would combine its teachings with Yang to determine appropriate and conventional dimensions for the components. The shared purpose of avoiding electrical failures and the similar staircase architecture provided a strong motivation to apply Yang’s specific dimensions to Kim’s general structure.
  • Expectation of Success (for §103 grounds): A POSITA would have a high expectation of success, as applying Yang's proven dimensions to Kim's analogous structure was a predictable design choice to optimize a known device configuration.

Ground 3: Claims 1, 4-7, 12, 16-17, and 19-20 are obvious over Lee

• Prior Art Relied Upon: Lee (Application # 2014/0191389).

• Core Argument for this Ground:

  • Prior Art Mapping: Petitioner argued that Lee also teaches all elements of the independent claims. Lee discloses a 3D memory device with a staircase structure and "pad portions PAD" (the landing pad) on its conductive layers. While one embodiment in Lee shows a pad aligned with the underlying conductive layer, Lee explicitly teaches an optional modification to address breakdown voltage issues. This modification involves forming a "barrier layer 28" at the end of the conductive steps. This barrier layer remains in the final product, effectively shortening the underlying conductive layer and causing the landing pad to overhang. This overhang creates an outward "lateral displacement" of the pad’s second side surface relative to the side surface of the underlying conductive layer, meeting the claim limitation.
  • Motivation to Combine (for §103 grounds): The motivation is contained within Lee itself, which teaches the barrier layer modification to "ensure sufficient distance" between stacked conductive layers and prevent electrical breakdown, directly addressing a known problem in the art.
  • Expectation of Success (for §103 grounds): A POSITA would have expected success in implementing the barrier layer as it was a specific solution proposed by Lee to improve the performance of its own disclosed device.

• Additional Grounds: Petitioner asserted additional obviousness challenges, including claims 3 and 18 as obvious over Lee and Haller (providing specific dimensions for Lee's barrier layer) and claims 13-15 as obvious over Lee and Park (teaching a "curved" landing pad surface to prevent short circuits).

4. Arguments Regarding Discretionary Denial

• Petitioner argued that discretionary denial would be inappropriate.
  • Fintiv Factors (§314(a)): Petitioner contended that denial under Fintiv is unwarranted because the trial date in the parallel district court litigation is not until June 2026, allowing ample time for a Final Written Decision. Furthermore, Petitioner argued that very little substantive progress has been made in the district court case concerning the ’838 patent and that it would stipulate not to pursue the same grounds in district court if review is instituted.
  • Same or Substantially the Same Art (§325(d)): Petitioner argued that denial under §325(d) would be improper because the core prior art references, Kim and Lee, raise issues unique from those considered during prosecution. Kim was not cited or considered by the examiner. While Lee was listed on the face of the patent, it was never used in a rejection or substantively discussed by the examiner, meaning the specific teachings relied upon in the petition were never evaluated.

5. Relief Requested

• Petitioner requests institution of Post Grant Review and cancellation of claims 1, 3-7, and 12-20 of Patent 12,010,838 as unpatentable.