Samsung Electronics Co Ltd v. DSS Technology Management Inc

1. Case Identification

• Case #: IPR2014-01493
• Patent #: 5,652,084
• Filed: September 12, 2014
• Petitioner(s): Samsung Electronics Co., Ltd
• Patent Owner(s): DSS Technology Management, Inc.
• Challenged Claims: 1-16

2. Patent Overview

• Title: Method for Reduced Pitch Lithography
• Brief Description: The ’084 patent discloses a method for semiconductor fabrication using double patterning lithography. The method involves forming, stabilizing, and patterning a first photoresist layer, then forming and patterning a second photoresist layer to create features with a smaller pitch (spacing) than is achievable with a single exposure process.

3. Grounds for Unpatentability

Ground 1: Claims 1-8, 12, 15-16 are anticipated under 35 U.S.C. §102(b) by Jinbo.

• Prior Art Relied Upon: Jinbo (Jap. Patent App. No. HEI 4[1992]-71222).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Jinbo discloses every limitation of the challenged claims. Jinbo teaches a double patterning method to form features closer than a system's resolution limit. It describes forming a first resist pattern on a substrate, stabilizing it by exposing it to a fluorine-containing plasma (a PRIST technique), forming a second resist pattern interleaved with the first, and using the combined pattern to etch an underlying layer. This process, including the stabilization step that renders the first resist insoluble to subsequent solvents and developers, allegedly meets all limitations of independent claims 1 and 15, as well as the specific limitations of the asserted dependent claims (e.g., using a positive photoresist and a PRIST technique).
  • Key Aspects: Petitioner contended that Jinbo explicitly teaches that its method resolves a 0.3 µm line and space pattern, which exceeds the described system’s resolution limit of 0.4 µm, directly corresponding to the ’084 patent’s core claim of achieving features "closer to one another than is possible through a single exposure to radiation."

Ground 2: Claims 1-7, 10, 12, 15-16 are anticipated under 35 U.S.C. §102(e) by Hsue.

• Prior Art Relied Upon: Hsue (Patent 5,667,940).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner asserted that Hsue, which was not considered during the original prosecution, also anticipates the challenged claims. Hsue describes a double coating method to fabricate fine lines with narrower spacing than the resolution limit. The process involves patterning a first photoresist layer and then stabilizing it with an ultraviolet (UV) baking process before depositing and patterning a second photoresist layer. This stabilization hardens the first layer so it is not removed during the second development step. Petitioner argued that this UV baking process (heating plus UV radiation) meets the "stabilizing" limitation of claim 1 and explicitly anticipates the limitations of dependent claim 10, which requires exposing the layer to radiation and heating.
  • Key Aspects: Hsue was presented as a complete and independent anticipatory reference. Petitioner emphasized that Hsue's disclosure of reducing feature spacing from a distance 'R' (resolution limit) to 'M' (misalignment tolerance), where M is much smaller than R, is a direct teaching of the ’084 patent’s central inventive concept.

Ground 3: Obviousness of Dependent and Independent Claims over Jinbo/Hsue Combinations

• Prior Art Relied Upon: Jinbo or Hsue in view of McColgin (Patent 4,931,351), Matthews (Patent 4,548,688), or Cooper (Patent 5,158,910).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that even if Jinbo or Hsue do not anticipate every claim, the remaining dependent claims would have been obvious by combining the primary Jinbo or Hsue methods with well-known, alternative techniques.
    • Claim 9 (Silylation): McColgin taught using silylation to stabilize a photoresist and improve etch resistance. A POSITA would have found it obvious to substitute the stabilization techniques in Jinbo or Hsue with McColgin’s known silylation method to achieve the same predictable result of a stabilized first layer.
    • Claims 10-11 (Radiation/Heat): Matthews taught stabilizing photoresist by exposing it to UV radiation while heating it, including at temperatures around 200° C. A POSITA would have been motivated to apply Matthews’ specific stabilization parameters to the general processes of Jinbo or Hsue to predictably enhance resist stability.
    • Claims 13-14 (Disposable Posts): Cooper taught using patterned photoresist features as "sacrificial plugs" or "disposable posts" that are later removed to define openings for contacts. A POSITA, seeking to increase device density, would have been motivated to use the closely-spaced features created by the Jinbo or Hsue methods as disposable posts as taught by Cooper, thereby increasing the density of contacts or other structures.
  • Motivation to Combine: The primary motivation was the simple substitution of one known, functionally equivalent element for another to obtain predictable results. A POSITA would have recognized these secondary references as providing a finite number of identified, predictable solutions to known problems in photolithography (e.g., resist stabilization, contact formation) and would have applied them to the advanced double-patterning frameworks of Jinbo and Hsue.
  • Expectation of Success: A POSITA would have had a high expectation of success because combining these teachings involved routine and predictable techniques in the field of semiconductor fabrication.

4. Key Claim Construction Positions

• "Stabilizing": Petitioner proposed construing this term as "performing a process that renders a material able to withstand subsequent processing steps, such as exposure to radiation, exposure to a solvent, or exposure to a developer." This construction was based on explicit examples provided in the ’084 patent’s specification.
• "Second Feature Distinct From the First Feature": Based on arguments made during prosecution to overcome prior art, Petitioner proposed this term requires that the second feature be "spatially separated from the first feature on the x axis." This construction was argued as necessary to capture the patentee's own definition used to secure allowance.
• "Disposable Post": Petitioner proposed construing this term as "a patterned feature that may be surrounded by another layer of material, and that may be removed to define an opening such as a contact, via, or interconnect layer opening." This construction was derived from the specification’s reference to another patent describing such posts.

5. Relief Requested

• Petitioner requested the institution of an inter partes review and cancellation of claims 1-16 of the ’084 patent as unpatentable.