PTAB

IPR2017-01792

SPTS Technologies Ltd v. Plasma Therm LLC

Log In
Key Events
Petition
petition Intelligence

1. Case Identification

2. Patent Overview

  • Title: Method for Plasma Dicing a Substrate
  • Brief Description: The ’705 patent describes a method for dicing a substrate (e.g., a semiconductor wafer) using plasma etching. The method involves an apparatus with a process chamber, a plasma source, a workpiece support including an electrostatic chuck, a mechanical partition, and a cover ring that does not contact the workpiece during the etching process.

3. Grounds for Unpatentability

Ground 1: Claims 1, 3-7, and 9-13 are obvious over Sekiya in view of Todorow, Westerman, Lea, and Kamaishi.

  • Prior Art Relied Upon: Sekiya (Patent 6,465,158), Todorow (Application # 2006/0000805), Westerman (Application # 2003/0216034), Lea (Application # 2002/0185226), and Kamaishi (Patent 8,191,505).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Sekiya taught the foundational method of plasma dicing a substrate mounted on a support film and frame. Todorow taught a conventional plasma etch chamber that supplied the remaining structural elements of claim 1, including a process chamber, plasma source, workpiece support with an electrostatic chuck, and a mechanical partition (termed a "plasma stabilizer"). Petitioner asserted that the final key limitation—a cover ring that does not contact the workpiece during etching—was a well-known feature taught by Westerman (a "confinement ring"), Lea (a "disc"), and Kamaishi (a "shadow ring"), all of which were shown spaced apart from the substrate.
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would have been motivated to implement Sekiya’s plasma dicing method using a known, suitable plasma etch apparatus like that of Todorow. Todorow’s apparatus was described as providing improved and stable etching processes. Furthermore, a POSITA would combine a non-contacting cover ring from Westerman, Lea, or Kamaishi into the Todorow system to perform the known function of protecting underlying components (like the workpiece frame or electrostatic chuck) from plasma exposure, a common design goal in plasma processing.
    • Expectation of Success: Petitioner contended that combining these known elements would yield only predictable results. Each component would perform its established function without any unexpected synergistic effect, leading a POSITA to have a high expectation of success.

Ground 2: Claims 14, 16-17, and 22-26 are obvious over the combination of Sekiya, Todorow, Westerman, Lea, and Kamaishi, further in view of Kim and Pellegrin.

  • Prior Art Relied Upon: The references from Ground 1, plus Kim (Application # 2006/0102286) and Pellegrin (Application # 2006/0164785).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground addressed independent claim 14, which differs from claim 1 by reciting "a plurality of mechanical partitions" and a "lifting mechanism" adjacent to the workpiece support, with the electrostatic chuck's outer diameter "extending to the lifting mechanism." Petitioner argued that the base combination of references from Ground 1 taught all limitations except these two. Kim was introduced to teach a plurality of mechanical partitions (two plates forming a screen) positioned between a plasma source and a workpiece. Pellegrin was introduced to teach a lifting mechanism (lift pins) located adjacent to and outside the outer periphery of an electrostatic chuck, thereby meeting the "extending to" limitation.
    • Motivation to Combine: The motivation for the base combination remained the same as in Ground 1. A POSITA would be motivated to incorporate Kim’s plurality of partitions to achieve the disclosed benefit of improved local control over ion charging levels, a desirable feature for enhancing etching processes. A POSITA would also incorporate the lift pin configuration from Pellegrin as a known and conventional technique to achieve the common outcome of handling wafers. Petitioner argued this was a simple design choice.
    • Expectation of Success: The addition of these further known elements for their known purposes would have been entirely predictable. The lift mechanism is a purely structural feature with no claimed function in the method, and the plural partitions would predictably perform their function of plasma control, leading to a high expectation of success.

4. Key Claim Construction Positions

  • "the cover ring does not touch the work piece during the etching": Petitioner argued this term, identified as the key feature for allowance during prosecution, should be construed as "no portion of the cover ring contacts the work piece during an etching operation." This construction was critical because Petitioner relied on prior art (Westerman, Lea, Kamaishi) that explicitly showed rings spaced apart from the workpiece to render this limitation obvious.
  • "cover ring": Petitioner proposed construing this term as "a structure in the shape of a ring, disposed in a plasma processing chamber, and covering any other structure to inhibit its exposure to plasma while leaving the object region to be plasma processed exposed." This functional construction allowed Petitioner to map the term to prior art structures with different names (e.g., confinement ring, shadow ring, disc) that performed the same protective function.

5. Key Technical Contentions (Beyond Claim Construction)

  • Hybrid Nature of Claims: A central contention was that the challenged method claims are improperly hybrid, containing an overwhelming number of conventional structural limitations. Petitioner argued that the actual method steps are merely (1) placing a workpiece, (2) generating plasma, and (3) etching. It was argued that many added structural limitations, such as the outer diameter of the electrostatic chuck or the presence of a lift mechanism in claim 14, have no functional nexus to the claimed method steps and were merely "throw-away" limitations added to overcome prior art.

6. Relief Requested

  • Petitioner requested the institution of an inter partes review and the cancellation of claims 1, 3-7, 9-14, 16-17, and 22-26 of the ’705 patent as unpatentable.