Taiwan Semiconductor Mfg Co Ltd v. DSS Technology Management Inc

1. Case Identification

• Case #: IPR2014-01030
• Patent #: 5,652,084
• Filed: June 24, 2014
• Petitioner(s): Taiwan Semiconductor Manufacturing Company, Ltd. (TSMC)
• 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 double-patterning lithography method for semiconductor fabrication to create features with spacing (pitch) smaller than what is achievable with a single exposure. The method involves forming and patterning a first photoresist layer, stabilizing it, and then forming a second, interleaved patterned photoresist layer to create a combined "single patterned layer" used for subsequent processing.

3. Grounds for Unpatentability

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

• Prior Art Relied Upon: Jinbo (Japanese Patent Application No. H04-71222).
• Core Argument:
  • Prior Art Mapping: Petitioner argued that Jinbo taught every element of the challenged claims. Jinbo described a double-patterning method to reduce device spacing beyond the resolution limit of a single exposure. This process included forming a first resist pattern, treating it with a fluorine-containing plasma to render it "insoluble," forming a second interleaved resist pattern, and using the combined pattern for subsequent processing. Petitioner contended that Jinbo's "insolubilizing" step was synonymous with the claimed "stabilizing" step, as it made the first resist layer resistant to the solvents and developers used for the second resist layer, meeting the ’084 patent's own definition.

Ground 2: Obviousness over Jinbo and Brownell - Claims 1-8, 12, 15, and 16 are obvious over Jinbo in view of Brownell.

• Prior Art Relied Upon: Jinbo (Japanese Patent Application No. H04-71222) and Brownell (Patent 4,591,547).
• Core Argument:
  • Prior Art Mapping: This ground was presented as an alternative to anticipation. Petitioner argued that Jinbo disclosed all elements of the claims except, potentially, for the full scope of the "stabilizing" limitation. The ’084 patent specification provides three examples of what a stabilized layer withstands: radiation, solvents, and developers. While Jinbo’s plasma treatment explicitly renders the first resist insoluble to solvents and developers, Brownell was cited to explicitly teach making a resist insensitive to subsequent radiation exposure. Brownell taught that exposing a patterned resist to a fluorine-containing plasma—the same technique used in Jinbo—makes the resist "neither photosensitive to further light, nor dissolvable by the usual solvents."
  • Motivation to Combine: A POSITA would combine these references because Jinbo expressly stated a goal of making the first patterned resist "insoluble" to prevent its destruction during the second patterning step and noted that methods other than its specific example could be used. Brownell taught a well-known technique for achieving this exact result, providing a known method to fulfill Jinbo’s stated objective. The combination represented using a known stabilization technique to improve a known double-patterning process.
  • Expectation of Success: A POSITA would have had a high expectation of success, as Brownell’s stabilization method was known to produce a predictable result: a robust resist layer resistant to subsequent processing steps, including radiation, solvents, and developers.

Ground 3: Obviousness over Jinbo, Brownell, and Cooper - Claims 13 and 14 are obvious over Jinbo in view of Brownell and Cooper.

• Prior Art Relied Upon: Jinbo (Japanese Patent Application No. H04-71222), Brownell (Patent 4,591,547), and Cooper (Patent 5,158,910).
• Core Argument:
  • Prior Art Mapping: This ground targeted claims 13 and 14, which specifically recite forming a "disposable post." Petitioner asserted that Jinbo and Brownell together taught the underlying double-patterning and stabilization method. Cooper was introduced to teach the concept of using patterned photoresist features as sacrificial plugs or "disposable posts" to define openings for contacts or other structures in subsequent layers.
  • Motivation to Combine: A POSITA would be motivated to use the high-resolution patterning technique of Jinbo to create the sacrificial plugs taught by Cooper. Cooper emphasized the desirability of using "high resolution capabilities of most imagable materials" for forming such plugs. Jinbo provided an improved method for creating resist features with resolution "below the resolution limit of the projection exposure apparatus." Therefore, a POSITA would have naturally looked to an advanced patterning technique like Jinbo's to implement the known sacrificial plug method of Cooper to achieve finer, more precise features.
  • Expectation of Success: The combination involved using an improved method for creating a known component (a patterned resist feature) for its established purpose (a sacrificial placeholder). The result—creating smaller, more precise openings using higher-resolution disposable posts—was predictable.
• Additional Grounds: Petitioner asserted additional obviousness challenges for specific dependent claims, arguing that claims 9 (reciting a "silylation technique" for stabilizing) are obvious over Jinbo in view of McColgin (Patent 4,931,351), and claims 10-11 (reciting stabilization by radiation and heating) are obvious over Jinbo in view of Matthews (Patent 4,548,688), both relying on a simple substitution rationale.

4. Key Claim Construction Positions

• "stabilizing": Petitioner argued this term should be construed as performing a process that renders a material able to withstand subsequent processing steps, including exposure to radiation, solvents, and/or developers, based on explicit examples in the ’084 patent’s specification. This construction was central to arguing that Jinbo’s "insolubilizing" step anticipated, or that Brownell rendered the step obvious.
• "disposable post": Petitioner proposed this term be construed to mean a patterned feature, such as a photoresist, that can be removed to define an opening (e.g., a contact or via) in another layer of material. This construction was crucial for mapping Cooper’s teaching of sacrificial plugs to the limitations of claims 13 and 14.

5. Relief Requested

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