Taiwan Semiconductor Mfg Co Ltd v. Uri Cohen

1. Case Identification

• Case #: IPR2018-00720
• Patent #: 7,199,052
• Filed: March 6, 2018
• Petitioner(s): Taiwan Semiconductor Manufacturing Company, LTD.
• Patent Owner(s): Dr. Uri Cohen
• Challenged Claims: 11, 19, 22-25, 35, 41-44, and 50-52

2. Patent Overview

• Title: Method for Making Metallic Interconnects with Multiple Seed Layers
• Brief Description: The ’052 patent relates to methods for forming metallic interconnect structures in semiconductor devices using a damascene process. The purported novelty involves a "two-step" seed layer deposition process to address challenges with continuous coverage inside small features and sufficient thickness on the field for uniform electroplating. This involves depositing a first seed layer with one technique (e.g., Physical Vapor Deposition, PVD) and a second, more conformal seed layer with another technique (e.g., Chemical Vapor Deposition, CVD).

3. Grounds for Unpatentability

Ground 1: Claims 19, 22-25, 35, 41-44, and 50-52 are obvious over Uzoh's Example 2

• Prior Art Relied Upon: Uzoh (Patent 6,126,806)
• Core Argument for this Ground: Petitioner argued that all challenged claims, except claim 11, are rendered obvious by the teachings of Example 2 in the Uzoh reference. Uzoh discloses a process for forming a multi-layer composite film to create robust metallic interconnects, which Petitioner asserted teaches or suggests all limitations of the challenged claims, including the use of a two-step, multi-technique seed layer deposition process.
  • Prior Art Mapping: Petitioner asserted that Uzoh's "Example 2" describes forming a composite film (film 30) that includes a first alloy seed layer (layer 6) and a second alloy seed layer (layer 27) as part of a metallic interconnect structure. For claim 19, which requires a PVD-deposited first seed layer and a second layer deposited by a different technique, Petitioner argued Uzoh explicitly lists PVD processes (sputtering, evaporation) as suitable for the first layer. Uzoh also lists CVD as a suitable method for the second layer. Petitioner contended a person of ordinary skill in the art (POSITA) would find it obvious to select a PVD technique for the first layer and a CVD technique for the second. The continuous coverage limitation was allegedly met because the ’052 patent itself admits that the conformal nature of CVD provides such coverage. Thickness limitations were allegedly met because Uzoh’s disclosed thickness ranges for its seed layers (e.g., 100-3000 Å for the first, 25-500 Å for the second) overlap with and suggest the claimed thicknesses.
  • Motivation to Combine: A POSITA would combine the disclosed deposition techniques from Uzoh because the reference presents a small, finite number of well-known options (PVD, CVD, plating) for each seed layer to solve the known problem of improving interconnect reliability. The choice of PVD for a thicker field layer and CVD for conformal sidewall coverage represented a simple design choice with predictable results.
  • Expectation of Success: A POSITA would have had a high expectation of success because the deposition techniques were conventional and their respective advantages—such as PVD's ability to deposit thicker layers and CVD's superior conformal coverage—were well-understood in the art for fabricating interconnects.

Ground 2: Claim 11 is obvious over Uzoh's Example 4

• Prior Art Relied Upon: Uzoh (Patent 6,126,806)
• Core Argument for this Ground: Petitioner argued that dependent claim 11, which depends from unchallenged claim 10, is rendered obvious by "Example 4" in Uzoh. This ground mirrors the logic of Ground 1 but applies it to a different embodiment within Uzoh (composite film 70) and a different claimed deposition sequence (CVD-first, PVD-second).
  • Prior Art Mapping: Petitioner argued Uzoh's Example 4, describing composite film 70, teaches all features of claim 10 and dependent claim 11. Claim 10 recites a first seed layer providing continuous coverage, a second PVD-deposited seed layer, and subsequent electroplating. Petitioner asserted it would have been obvious to a POSITA to use a CVD process for Uzoh's first alloy seed layer (layer 56), as Uzoh discloses "other processes" could be used, and CVD was a known, suitable, and predictable option for depositing such layers to achieve the claimed continuous coverage. Uzoh then explicitly teaches that the second copper seed layer (layer 60) may be formed by sputtering, which is a PVD process. The limitation in dependent claim 11 that the first seed layer be deposited by CVD was therefore allegedly obvious.
  • Motivation to Combine: The motivation was based on an "obvious to try" rationale. Given a design need to create improved interconnects and a finite list of deposition options in Uzoh (PVD, CVD, etc.), a POSITA would have found it obvious to try using CVD for the first seed layer to achieve conformal coverage and PVD for the second layer, especially since both were known techniques for these materials.
  • Expectation of Success: Success was predictable because the properties and outcomes of using CVD for conformal coverage and PVD for subsequent deposition were well-established in the field of semiconductor fabrication.

4. Key Claim Construction Positions

• "over": Petitioner argued this term should be construed to mean "above," without requiring direct contact. This construction is critical because the layers in the Uzoh reference (e.g., first seed layer, second seed layer, and electroplated layer) are often separated by intervening layers. Petitioner cited intrinsic evidence from the ’052 patent, where dependent claims recite barrier layers being deposited "over" a surface before a seed layer, demonstrating that "over" accommodates intermediate layers.
• "seed layer": Petitioner proposed that "seed layer" should be construed as "an electrically conductive layer that facilitates growth of a conductive material." This broad, functional definition supports its argument that multiple layers in Uzoh's composite films qualify as seed layers.

5. Arguments Regarding Discretionary Denial

• Petitioner argued that discretionary denial under the General Plastics factors (§325(d)) would be inappropriate. It acknowledged a prior IPR petition was filed against the ’052 patent but asserted that this petition challenges different claims. Further, it stated that the Patent Owner had not yet filed a preliminary response in the earlier case and the Board had not made an institution decision, making this follow-on petition efficient and not abusive. Petitioner contended that the public interest in canceling invalid patent claims weighs against discretionary denial.

6. Relief Requested

• Petitioner requested the institution of an inter partes review and the cancellation of claims 11, 19, 22-25, 35, 41-44, and 50-52 of Patent 7,199,052 as unpatentable under 35 U.S.C. §103.