Semiconductor Components Industries, LLC v. Greenthread, LLC

1. Case Identification

• Case #: IPR2023-01244
• Patent #: 11,121,222
• Filed: July 27, 2023
• Petitioner(s): Semiconductor Components Industries, LLC
• Patent Owner(s): Greenthread, LLC
• Challenged Claims: 44

2. Patent Overview

• Title: CMOS Device Having Graded Dopant Concentrations
• Brief Description: The ’222 patent relates to a Complementary Metal-Oxide Semiconductor (CMOS) device featuring graded dopant concentrations within specific regions. The invention purports to create static, unidirectional electric drift fields that aid the movement of charge carriers from the device's surface layer towards the substrate, particularly to areas without active regions.

3. Grounds for Unpatentability

Ground 1: Claim 44 is obvious over Payne (Patent 4,684,971)

• Prior Art Relied Upon: Payne (Patent 4,684,971)
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Payne, which teaches a CMOS structure for high packing density, discloses all limitations of claim 44. Payne’s nested well structure, comprising shallow wells (e.g., region 18) formed within deeper "tub regions" (e.g., region 15), was asserted to correspond to the claimed "well region" disposed in a "single drift layer." Petitioner contended that Payne’s disclosed "high-low implant profile" (Fig. 11), which shows dopant concentration decreasing with depth, is the claimed "graded concentration of dopants." This graded profile in both the drift layer (tub region 15) and the well region (shallow well 18) inherently creates the first and second static unidirectional electric drift fields, respectively, that aid the movement of minority carriers away from the surface and toward the substrate where no active regions exist.
  • Motivation to Combine (for §103 grounds): Not applicable (single reference ground).
  • Expectation of Success (for §103 grounds): Not applicable (single reference ground).

Ground 2: Claim 44 is obvious over Sakai (Patent 4,907,058) in view of Kawagoe (Patent 6,043,114)

• Prior Art Relied Upon: Sakai (Patent 4,907,058), Kawagoe (Patent 6,043,114)
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Sakai discloses a "twin double well" structure for high-packing-density CMOS devices, which is a nested well structure similar to Payne's. This structure includes shallow wells (e.g., P-well 4, N-well 5) formed in deep wells (P-well 2, N-well 3), which Petitioner mapped to the claimed "well region" and "single drift layer." While Sakai teaches a high-to-low dopant concentration between the shallow and deep wells, Kawagoe was introduced to explicitly teach implementing this as a gradual, downward-sloping concentration profile. Kawagoe teaches that grading the dopant concentration in wells "gradually lowered in the depthwise direction" reduces soft errors by creating a concentration gradient that attracts unwanted alpha-particle-generated carriers into the substrate body.
  • Motivation to Combine (for §103 grounds): Petitioner asserted a POSITA would combine Sakai and Kawagoe because both are Hitachi patents directed at improving CMOS devices. A POSITA would have been motivated to apply Kawagoe's known technique for reducing soft errors (using graded dopant profiles) to Sakai's high-packing-density nested well structure, particularly since such structures are used in memory devices (e.g., SRAMs) which are susceptible to soft errors.
  • Expectation of Success (for §103 grounds): A POSITA would have had a reasonable expectation of success because fabricating graded dopant profiles using well-known ion implantation and thermal drive-in techniques was a predictable and established process in the art, as evidenced by numerous references including Payne and Kawagoe itself.

4. Key Claim Construction Positions

• Petitioner stated it did not believe any terms required construction but noted that the Patent Owner and a third party (Intel) had taken positions on certain terms in a related IPR.
• Petitioner argued that claim 44 is unpatentable under either the Patent Owner's or Intel's proposed constructions for key terms. For example, Petitioner contended that the structures in Payne and Sakai satisfy the limitations of "single drift layer," "well region," and "active region" regardless of which party's proposed definition is adopted, thereby obviating the need for the Board to resolve the construction dispute.

5. Key Technical Contentions (Beyond Claim Construction)

• A central technical contention was that a downward-sloping, graded dopant concentration inherently and necessarily creates a "built-in" static, unidirectional electric drift field.
• Petitioner relied on prosecution history from a parent patent where the applicant made this same argument, citing prior art like Jastrzebski and Kamins, to assert that this principle was well-understood. This contention underpins the argument that both Payne and the Sakai/Kawagoe combination teach the claimed drift fields, even without explicitly naming them, as a natural consequence of their disclosed graded dopant profiles.

6. Arguments Regarding Discretionary Denial

• §314(a) / Fintiv: Petitioner argued against discretionary denial under Fintiv, asserting the petition presents compelling evidence of unpatentability, particularly the single-reference obviousness ground over Payne. It also noted that a trial date in the parallel district court case was not yet set and that the median time-to-trial in the District of Delaware would place any trial well after a Final Written Decision (FWD) would issue.
• §325(d) / Cumulative Art: Petitioner contended that denial under §325(d) was unwarranted because the Examiner made a material error during prosecution by overlooking the key nested-well and graded-profile teachings of Payne and Sakai. Instead, the Examiner relied solely on a non-prior art reference (Hong) for allowance. Petitioner argued the asserted grounds based on Payne, Sakai, and Kawagoe are not cumulative to any art considered during prosecution of the ’222 patent or its parent applications.
• General Plastic Factors: Petitioner argued that filing this petition (Petition II) separate from a prior petition (Petition I) against other claims of the '222 patent was justified. It claimed that claim 44 is materially different in scope from the claims in Petition I, uniquely requiring a "single drift layer" and a "well region disposed in the single drift layer," which are best addressed by the nested-well art of Payne and Sakai, art not used in Petition I.

7. Relief Requested

• Petitioner requested institution of an inter partes review and cancellation of claim 44 of Patent 11,121,222 as unpatentable under 35 U.S.C. §103.