PTAB

IPR2021-00095

Canadian Solar Inc v. Solaria Corp

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Method for Scribing a Solar Cell
  • Brief Description: The ’707 patent discloses a method for laser scribing solar cells. The method involves placing a solar cell with a metalized backside on a platen, using a laser to ablate the backside to form a scribe region of a specific depth (40% to 60% of the cell thickness), and removing/capturing the resulting vaporized material with a vacuum.

3. Grounds for Unpatentability

Ground 1: Obviousness over Jinno-205/Suutarinen - Claims 1, 2, 6, 8, 9, 12-16 are obvious over Jinno-205 in view of Suutarinen.

  • Prior Art Relied Upon: Jinno-205 (Japanese Unexamined Patent Application Publication JP 2008-60205A) and Suutarinen (Application # US 2008/00671760 A1).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that the combination of Jinno-205 and Suutarinen taught all limitations of independent claim 1. Jinno-205 disclosed a method for backside laser scribing of a solar cell with metalized electrodes to a depth of 35% to 65% of the cell's thickness, which overlaps the claimed 40-60% range. Suutarinen disclosed a laser cutting system for semiconductor wafers that operates in a vacuum environment, using ablation to cut the material and a gas flow/vacuum system to remove the resulting plasma cloud and debris from the ablation site.
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSA) would combine Jinno-205's specific solar cell scribing process with Suutarinen's more general ablation and debris removal system. The motivation was to achieve the known benefits taught by Suutarinen—namely, increasing processing speed, minimizing heat-affected zones, and reducing particulate contamination—when performing the solar cell scribing taught by Jinno-205. Both references are in the analogous art of laser singulation of semiconductor wafers.
    • Expectation of Success: A POSA would have had a reasonable expectation of success, as the combination involved applying a known debris removal technique (Suutarinen) to a known scribing process (Jinno-205) to achieve predictable improvements in efficiency and quality.

Ground 2: Obviousness of V-Shaped Scribe - Claim 10 is obvious over Jinno-205/Suutarinen in view of Liu.

  • Prior Art Relied Upon: Jinno-205, Suutarinen, and Liu (Patent 6,580,054).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground built upon the core combination of Jinno-205 and Suutarinen. To meet the additional limitation of claim 10 ("the scribe region is V-shaped"), Petitioner relied on Liu. Liu explicitly taught that laser-scribing V-shaped grooves is preferred for creating more uniform and predictable breaks when separating semiconductor dies.
    • Motivation to Combine: A POSA, seeking to improve the cleaving uniformity of the solar cell scribed according to Jinno-205, would have been motivated to incorporate the V-shaped groove taught by Liu. Liu addressed the same problem of achieving predictable breaks after scribing. This modification was presented as a predictable design choice to improve a known process.

Ground 3: Obviousness of Repetition Rate - Claims 17-18 are obvious over Jinno-205/Suutarinen in view of Spectra-Physics.

  • Prior Art Relied Upon: Jinno-205, Suutarinen, and Spectra-Physics (a 2011 product brochure).

  • Core Argument for this Ground:

    • Prior Art Mapping: To meet the repetition rate limitation of claim 17 (100-300 kHz), Petitioner pointed to Spectra-Physics. This brochure from a major laser manufacturer described a 532 nm laser for scribing solar cells with "excellent power and performance at 120 kHz pulse repetition frequency and beyond." This disclosed rate falls squarely within the claimed range.
    • Motivation to Combine: A POSA implementing the Jinno-205/Suutarinen system would have been motivated to use the laser parameters recommended by a leading manufacturer like Spectra-Physics. The motivation was to achieve the benefits described in the brochure, such as a "smooth scribe floor" and "clean and effective isolation scribes."

  • Additional Grounds: Petitioner asserted additional obviousness challenges for other dependent claims. These relied on the core Jinno-205/Suutarinen combination and added further references to teach specific dimensional or operational parameters, including: Morad (Application # US 2015/0349167) for a standard 156 mm cell length (claim 13); Shamoun (Application # US 2010/0155379) for maintaining a constant laser height (claim 19); and Daly (Patent 3,626,141) for a scribe width variation tolerance of 5 µm or less (claim 20).

4. Arguments Regarding Discretionary Denial

  • Petitioner argued extensively that discretionary denial under either §314(a) or §325(d) would be inappropriate.
  • §314(a) (Fintiv Factors): Petitioner contended that factors related to parallel district court and ITC litigation weighed against denial. Key arguments included that no trial date was set in the district court case, the IPR petition challenged a broader set of claims than the parallel cases, and the IPR was filed expeditiously after it became available nine months post-issuance. Petitioner also noted that ITC invalidity decisions are not preclusive.
  • §325(d): Petitioner argued that the challenge did not rely on the same or substantially the same prior art or arguments previously presented to the USPTO. The primary references, Jinno-205 and Suutarinen, were not considered during the prosecution of the ’707 patent, which had a minimal history with only a single rejection for double patenting.

5. Relief Requested

  • Petitioner requested institution of an inter partes review and cancellation of claims 1, 2, 6, 8-10, and 12-20 of the ’707 patent as unpatentable.