Samsung Electronics Co Ltd v. Trenchant Blade Technologies LLC

1. Case Identification

• Case #: IPR2021-00257
• Patent #: 7,056,821
• Filed: December 1, 2020
• Petitioner(s): Samsung Electronics Co., Ltd.
• Patent Owner(s): Trenchant Blade Technologies LLC.
• Challenged Claims: 1-14

2. Patent Overview

• Title: Method for Manufacturing a Dual Damascene Structure
• Brief Description: The ’821 patent discloses a method for manufacturing a dual damascene structure in a semiconductor device using a "trench-first" approach. This method purports to solve problems associated with conventional "via-first" processes, such as oxidation of underlying metal layers and the formation of undesirable "fences" or "micro trenches."

3. Grounds for Unpatentability

Ground 1: Claims 1-14 are obvious over Hussein in view of Feldner.

• Prior Art Relied Upon: Hussein (Patent 6,329,118) and Feldner (Patent 6,300,235).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Hussein taught nearly every element of the challenged claims, including a "trench-first" method for forming a dual damascene structure. Hussein’s method involved forming layers on a substrate, etching a trench to a predetermined depth within a dielectric layer, filling the trench with a sacrificial material, and subsequently patterning and etching a via through the sacrificial material. Petitioner contended that the only significant step of claim 1 not explicitly taught by Hussein was the planarization of the sacrificial layer before patterning the via. Feldner, which also addressed trench-first dual damascene fabrication, was argued to explicitly teach this missing step. Feldner disclosed planarizing a sacrificial layer (a flowable oxide) to create a substantially planar surface, which it explained was advantageous for improving the resolution and control of subsequent photolithography steps. Petitioner asserted that Feldner’s teaching of planarization directly supplied the limitation absent from Hussein.
  • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine Hussein and Feldner to improve the manufacturing process. A POSITA reviewing Hussein's method would recognize that the non-planar surface resulting from filling the trench with sacrificial material could complicate the subsequent photolithography step for defining the via. Feldner taught that planarizing this exact type of layer solved this known problem. Therefore, a POSITA would have been motivated to incorporate Feldner’s planarization teaching into Hussein’s process to improve the planarity of the sacrificial material, thereby enhancing the reliability and precision of the via formation step.
  • Expectation of Success: A POSITA would have a high expectation of success. The combination involved applying a known technique (planarization) from Feldner to a well-understood and similar process (Hussein's trench-first method) to achieve a predictable and desired result—an improved planar surface for subsequent processing. Both references operated in the same technical field and addressed similar fabrication challenges.

Ground 2: Claim 14 is obvious over Hussein in view of Feldner and Campana.

• Prior Art Relied Upon: Hussein (Patent 6,329,118), Feldner (Patent 6,300,235), and Campana (Application # 2002/0119250).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground built upon Ground 1 and specifically addressed the limitation in claim 14 requiring the "second etching stop layer" to comprise an "anti-reflection layer." Petitioner argued that Hussein’s "hard mask layer" served as the second etching stop layer. While Hussein’s overall method was concerned with photolithography, it did not explicitly state its hard mask was anti-reflective. Feldner taught using an organic anti-reflection coating (ARC) that also functioned as an etch stop. To the extent an organic layer might be considered unsuitable, Petitioner introduced Campana, which taught that an inorganic silicon carbide layer could be used as both a hard mask and an anti-reflection layer in dual damascene fabrication. Campana explicitly disclosed its silicon carbide hard mask was used as an ARC for deep ultraviolet (DUV) lithography.
  • Motivation to Combine: The motivation was to further improve the lithographic process in the Hussein/Feldner combination. Hussein itself discussed the need to absorb light and reduce reflections during lithography. A POSITA seeking to optimize the process would be motivated to select a hard mask material that also provided anti-reflective properties. Campana taught that a single silicon carbide layer could serve this dual function, offering an efficient solution. This would be a simple and logical substitution of one known element (a generic hard mask) for a more functional one (a hard mask with ARC properties) to achieve a known benefit.
  • Expectation of Success: A POSITA would expect success in substituting Hussein's hard mask with Campana's dual-function layer. It was a straightforward substitution of one material for another to gain a known, advantageous property (anti-reflection) without changing the fundamental process flow.

4. Arguments Regarding Discretionary Denial

• Petitioner argued that discretionary denial under §325(d) was inappropriate because the primary prior art references relied upon in the petition—Hussein, Feldner, and Campana—were never considered by the USPTO during the original prosecution of the ’821 patent.
• Petitioner further argued that discretionary denial under §314(a) and the Fintiv factors was unwarranted. The petition was filed only 11 days after the co-pending district court litigation was initiated, meaning there was minimal investment by the court or parties. Furthermore, the district court case was a declaratory judgment action for non-infringement, presenting no overlap with the invalidity issues raised in the IPR petition.

5. Relief Requested

• Petitioner requested institution of an inter partes review and cancellation of claims 1-14 of the ’821 patent as unpatentable.