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
• Brief Description: The ’052 patent discloses methods for forming metallic interconnect structures in semiconductor devices. The purported invention is a two-step seed layer deposition process designed to overcome challenges in fabricating smaller interconnects, ensuring both continuous coverage inside openings to prevent voids and sufficient thickness on the surrounding field to enable uniform electroplating.

3. Grounds for Unpatentability

Ground 1: Claims 19, 22-25, 35, 41-43, 44, and 50-52 are obvious over Uzoh.

• Prior Art Relied Upon: Uzoh (Patent 6,126,806). The arguments rely primarily on disclosures related to "Example 2" in the reference.
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Uzoh’s Example 2 discloses a method for forming a multi-layer composite film for metallic interconnects that teaches or suggests every limitation of the challenged independent claims. Uzoh’s composite film includes a first alloy seed layer, a second alloy seed layer, and a final bulk copper layer formed by electroplating. Petitioner asserted that Uzoh teaches depositing the first seed layer using a Physical Vapor Deposition (PVD) technique to a thickness that overlaps the claimed ranges (e.g., >520 Å). Uzoh also teaches depositing the second seed layer using Chemical Vapor Deposition (CVD), a well-known conformal process that would provide the claimed continuous coverage inside the interconnect opening. Furthermore, Uzoh’s disclosed thickness ranges for the first and second seed layers suggest embodiments where the first layer is thicker than the second, and their combined thickness meets the requirement for a low electrical resistance path.
  • Motivation to Combine (for §103 grounds): As a single-reference ground, the motivation was framed as an obvious selection from a finite number of known design choices. Petitioner contended a POSITA would be motivated to select a PVD process for the first seed layer and a CVD process for the second from the options disclosed in Uzoh. This combination would predictably achieve the dual goals of a thick, low-resistance field layer (a known characteristic of PVD) and a conformal, continuous layer inside the feature (a known characteristic of CVD), thereby improving interconnect reliability, which was Uzoh's stated goal.
  • Expectation of Success: A POSITA would have had a high expectation of success because PVD and CVD were well-known, predictable, and commonly used techniques for depositing seed layers. The ’052 patent itself acknowledged that the conformal nature of CVD was well-known in the art for providing continuous coverage.

Ground 2: Claim 11 is obvious over Uzoh.

• Prior Art Relied Upon: Uzoh (Patent 6,126,806). The arguments rely primarily on disclosures related to "Example 4" in the reference.
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Uzoh’s Example 4, which describes another multi-seed layer composite film, renders the features of claim 10 (from which challenged claim 11 depends) and claim 11 itself obvious. Example 4 discloses a first copper alloy seed layer and a second copper seed layer, followed by an electrodeposited bulk copper film. Petitioner asserted it would have been obvious to a POSITA to form Uzoh’s first seed layer using CVD to achieve the continuous coverage required by claim 10. Uzoh explicitly teaches that the second seed layer can be formed by sputtering (a PVD process), which meets the PVD limitation for the second seed layer in claim 10. Finally, Uzoh's disclosed thickness range for the first seed layer (10-200 Å) overlaps with the limitation in dependent claim 11 requiring a thickness less than about 100 Å.
  • Motivation to Combine (for §103 grounds): Petitioner argued that Uzoh discloses "other processes" for depositing its first seed layer, which would have explicitly suggested using any available, suitable technique, including CVD. Given the known benefits of CVD for creating continuous layers in high-aspect-ratio features, a POSITA seeking to implement Uzoh's invention in modern processes would have been motivated to select CVD for the first layer. The motivation was based on an obvious-to-try rationale, given the finite number of predictable solutions for seed layer deposition.
  • Expectation of Success: A POSITA would have expected success in applying a CVD process to form Uzoh’s first seed layer, as CVD was a well-established method for depositing thin, conformal copper alloy films of the type disclosed in Uzoh.

4. Key Claim Construction Positions

• "over": Petitioner argued this term is critical to the invalidity analysis and should be construed as "above," without requiring direct physical contact. This construction permits intervening layers between, for example, a seed layer and the substrate, or between two seed layers. This interpretation is allegedly supported by the ’052 patent’s claims and specification, where dependent claims explicitly add a barrier layer between the substrate and the "first seed layer over the substrate." This construction is necessary because the Uzoh reference discloses intervening layers within its composite film structure.

5. Arguments Regarding Discretionary Denial

• Petitioner argued that discretionary denial under §314(a) or §325(d) would be inappropriate. The petition was filed less than two months after a separate petition by Petitioner against different claims of the same ’052 patent. At the time of filing, the Patent Owner had not filed a preliminary response to the earlier petition, and the Board had not yet issued an institution decision. Petitioner asserted the instant petition was not abusive and that the grounds were not the same or substantially the same as those previously presented.

6. Relief Requested

• Petitioner requests institution of an inter partes review and cancellation of claims 11, 19, 22-25, 35, 41-44, and 50-52 of the ’052 patent as unpatentable.