PTAB

IPR2018-00446

Applied Materials Inc v. Uri Cohen

Log In
Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Multiple Seed Layers for Metallic Interconnects
  • Brief Description: The ’226 patent discloses a method for fabricating metallic interconnects in semiconductor devices. The method involves depositing a composite seed layer, comprising a first "substantially conformal seed layer" followed by a second "substantially non-conformal seed layer," prior to electroplating copper to fill features like vias and trenches.

3. Grounds for Unpatentability

Ground 1: Obviousness over Maydan, Rathore, and Brown - Claims 1-3, 5-8, 11-13, 21-24, and 27-28 are obvious over Maydan in view of Rathore and Brown.

  • Prior Art Relied Upon: Maydan (Patent 6,372,633), Rathore (Patent 6,069,068), and Brown (Patent 6,187,670).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Maydan taught the foundational method of independent claim 1: forming an interconnect by depositing a conformal copper "wetting layer" (a substantially conformal seed layer) using Chemical Vapor Deposition (CVD), followed by a second seed layer using Physical Vapor Deposition (PVD), and then electroplating. Brown was cited to teach that a standard PVD sputtering process inherently produces a non-conformal layer with sidewall coverage of 5% or less relative to the field thickness, which directly meets the ’226 patent’s definition of a "substantially non-conformal seed layer" (less than 25%). Rathore was used to supply the missing limitation regarding relative layer thickness, teaching that in a multi-layer seed structure, the PVD layer should be thicker than the CVD layer to minimize contamination and improve electromigration resistance.
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine these references as they all address the common problem of improving copper interconnect structures for electroplating. A POSITA would have been motivated to optimize the process in Maydan by applying the specific teachings of Rathore regarding layer thicknesses and Brown regarding the inherent properties of PVD. The goal would be to predictably reduce known issues like CVD-related contamination and improve interconnect reliability, as taught by Rathore, using the standard, well-understood PVD process described by Brown.
    • Expectation of Success: A POSITA would have a high expectation of success because the combination involved applying known techniques (CVD and standard PVD) and optimizing well-understood parameters (layer thickness) to achieve predictable improvements in a known process.

Ground 2: Obviousness over Maydan, Rathore, Brown, and Sherman - Claims 4 and 29 are obvious over the combination of Maydan, Rathore, Brown, and Sherman.

  • Prior Art Relied Upon: Maydan (Patent 6,372,633), Rathore (Patent 6,069,068), Brown (Patent 6,187,670), and Sherman (Patent 6,342,277).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground targets claims 4 and 29, which require depositing the conformal seed layer or barrier layer using Atomic Layer Deposition (ALD). While the primary combination does not teach ALD, Sherman explicitly disclosed using ALD to deposit both barrier layers (e.g., TiN) and copper seed layers. Sherman highlighted that ALD produces "perfectly conformal" films at low temperatures.
    • Motivation to Combine: A POSITA would be motivated to substitute the CVD deposition step in the primary combination (from Maydan) with the ALD technique taught by Sherman. The motivation stemmed from the known benefits of ALD, such as superior conformality, lower manufacturing costs, and process simplification, all of which were desirable for the interconnect fabrication process described by Maydan.
    • Expectation of Success: The substitution of one known conformal deposition technique (CVD) with another (ALD) to achieve the same result (a conformal layer) was a simple design choice with a predictable and successful outcome.

Ground 3: Obviousness over Maydan, Rathore, Brown, and Chiang - Claim 10 is obvious over the combination of Maydan, Rathore, Brown, and Chiang.

  • Prior Art Relied Upon: Maydan (Patent 6,372,633), Rathore (Patent 6,069,068), Brown (Patent 6,187,670), and Chiang (Patent 6,398,929).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground targets claim 10, which requires the non-conformal layer to be deposited by Self Ionized Plasma (SIP) sputtering. The primary combination taught using a general PVD technique. Chiang specifically disclosed SIP as a PVD sputtering technique that produces a "substantially non-conformal seed layer," providing explicit thickness values showing sidewall coverage of less than 20% of the field (blanket) thickness.
    • Motivation to Combine: A POSITA implementing the PVD step from the primary combination would have looked to known, available sputtering techniques. Chiang presented SIP as an advantageous and well-understood PVD method. A POSITA would have been motivated to use Chiang's SIP technique as a specific implementation of the general PVD step to form the non-conformal layer, as it was a known method for achieving the desired non-conformal profile.
    • Expectation of Success: Employing a specific, well-known type of PVD (SIP) to perform a general PVD step was a simple application of a known technique to achieve a predictable result.

4. Key Claim Construction Positions

  • "Substantially Conformal" and "Substantially Non-Conformal" Seed Layers: Petitioner argued that the Patent Owner acted as his own lexicographer by providing explicit definitions for these key terms in the specification. A "substantially conformal seed layer" was defined as having a sidewall thickness of about 25-100% of its field thickness. A "substantially non-conformal seed layer" was defined as having a sidewall thickness of less than about 25% of its field thickness. These definitions were central to mapping the prior art.

5. Key Technical Contentions (Beyond Claim Construction)

  • Priority Date Challenge: Petitioner contended that the ’226 patent was not entitled to the filing date of its parent applications (filed prior to October 1999). It was argued that the specific numerical ranges (25-100% and <25%) defining the key claim terms were introduced for the first time in the application leading to the ’226 patent. Therefore, this constituted new matter not supported by the parent specifications, invalidating the priority claim and making references filed after the parent applications, but before the ’226 patent’s effective filing date, valid prior art.

6. Relief Requested

  • Petitioner requested institution of an inter partes review and cancellation of claims 1-8, 10-13, 21-24, and 27-29 of the ’226 patent as unpatentable under 35 U.S.C. §103.