PTAB

IPR2016-00287

Intel Corp v. DSS Technology Management Inc

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Semiconductor Structure and Fabrication Method
  • Brief Description: The ’552 patent relates to a method for manufacturing semiconductor transistors. The invention addresses the problem of sidewall spacer erosion during the formation of contact openings by using an anisotropic etching process to maintain a "substantially rectangular" spacer profile, thereby preventing short-circuits with adjacent conductive layers.

3. Grounds for Unpatentability

Ground 1: Anticipation by Heath - Claims 1-2 and 4-7 are anticipated by Heath.

  • Prior Art Relied Upon: Heath (Patent 4,686,000).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Heath, filed nearly a decade before the ’552 patent’s priority date, discloses every element of the challenged claims. Heath addresses the identical problem of preventing short-circuits during contact formation. It teaches a transistor structure comprising a conductive layer (gate electrode 16), insulating layers (oxide layer 24), a contact region (contact window 32), an insulating spacer (sidewall spacer 16a), and an etch stop material (layer 10). Critically, Heath’s process uses anisotropic etching that leaves a "vertical 'stick'" of etch stop material on "vertical sidewall surfaces," resulting in a 90° spacer profile relative to the substrate. This structure meets the "substantially rectangular" profile and the specific angle limitation of claim 1.
    • Prior Art Mapping (Dependent Claims): Petitioner asserted Heath also teaches the limitations of the dependent claims. Heath explicitly states its etch stop is preferably silicon nitride (anticipating claim 2), and its figures show a spacer surface without overlying etch stop material (anticipating claims 4-5), an additional insulating layer (layer 34) over the etch stop (anticipating claim 6), and the subsequent addition of conductive material to the contact region (anticipating claim 7).

Ground 2: Obviousness of Claim 3 over Heath, Hawley, and Chappell - Claim 3 is obvious over Heath in view of Hawley and Chappell.

  • Prior Art Relied Upon: Heath (Patent 4,686,000), Hawley (European Patent Publ. No. 0592078), and Chappell (Patent 5,541,427).
  • Core Argument for this Ground:
    • Prior Art Mapping: Claim 3 depends on claim 1 and requires the etch stop material to be silicon dioxide. Petitioner argued that Heath discloses using materials other than its preferred silicon nitride for the etch stop. Hawley, which addresses the same technology, explicitly teaches that an etch-stop layer "may comprise a thin layer of silicon dioxide." Because claim 1 requires the etch stop and insulating spacer to be different materials, a POSITA would need to use a non-oxide spacer. Chappell provides a ready solution, teaching the well-known use of nitride spacers adjacent to a gate stack.
    • Motivation to Combine: A POSITA would combine these references as they all relate to forming contact openings in transistors. It would have been a simple and known design choice to substitute Heath's etch stop with the silicon dioxide taught by Hawley. To maintain the required material differentiation from the new etch stop, the POSITA would have been motivated to use a common alternative spacer material like the nitride spacers taught in Chappell to minimize current leakage and short circuits.
    • Expectation of Success: A POSITA would have had a high expectation of success, as substituting well-known, compatible materials for etch stops and spacers was a routine and predictable practice in semiconductor fabrication.

Ground 3: Obviousness over Heath and Dennison - Claims 1-2 and 4-7 are obvious over Heath in view of Dennison.

  • Prior Art Relied Upon: Heath (Patent 4,686,000) and Dennison (Patent 5,338,700).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner presented this ground to demonstrate obviousness even under a potentially narrow construction of the claim 1 "angle" limitation, where the required angle exists only on a partially etched portion of the spacer. While Heath's figures show the etch removing the entire top of the spacer, Dennison explicitly discloses a process that etches only partially through a sidewall spacer, leaving a "substantially vertical portion at the top of the insulating spacer."
    • Motivation to Combine: A POSITA would combine Heath and Dennison to optimize the contact formation process. Heath teaches that proper alignment of the contact window is critical to avoid short circuits. Dennison teaches that precise alignment can result in a partially etched spacer that retains a vertical side. A POSITA seeking to implement Heath's goal of superior alignment would be motivated by Dennison to adjust the etch alignment slightly, a matter of nanometers, which would predictably result in only partial etching of the spacer, thereby creating the claimed structure.
    • Expectation of Success: A POSITA would expect success because controlling the lateral extent of an etch through precise mask alignment was a well-understood and fundamental technique for process control in semiconductor manufacturing.
  • Additional Grounds: Petitioner asserted an additional obviousness challenge for claim 3 based on the combination of Heath, Dennison, Hawley, and Chappell, leveraging the same arguments presented in the grounds above.

4. Key Claim Construction Positions

  • Petitioner proposed a construction for the key limitation in claim 1: "a side of the insulating spacer has an angle relative to the substrate surface that is either a right angle or an acute angle of more than 85°".
    • Proposed Construction: "a side of the insulating spacer has an angle relative to the horizontal substrate surface that is greater than 85° and less than or equal to 90°".
    • Rationale: Petitioner argued this construction was compelled by the plain language ("a side," meaning any side) and the patent specification, which illustrates the angle being measured at different locations on the spacer. This construction was central to the argument that Heath's disclosure of "vertical" (i.e., 90°) sidewalls anticipated the claim.

5. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-7 of Patent 6,784,552 as unpatentable.