PTAB

IPR2018-01406

Intel Corporation v. Godo Kaisha IP Bridge 1

Title: Semiconductor Devices and Manufacturing Methods
Brief Description: The ’409 patent discloses semiconductor devices and fabrication methods intended to solve problems arising from overetching during manufacturing. The purported solution involves a device structure where an isolation region has a top surface that is at a higher level than the surface of the transistor's active area, allegedly preventing the formation of recesses when creating connections.

Prior Art Relied Upon: Cederbaum (Patent 5,275,963).
Core Argument for this Ground:
- Prior Art Mapping: Petitioner argued that Cederbaum, which was not considered during prosecution, teaches all limitations of the challenged claims. Cederbaum describes a method for manufacturing SRAM devices, including a semiconductor substrate, an active region, a field recess oxide (ROX) isolation region (a LOCOS structure), a polysilicon interconnection on the isolation, an insulating film, and a contact hole containing a conductive layer connecting the active region and the interconnection. For limitation 1[h], Petitioner asserted that Cederbaum's ROX structure has a portion connected to the conductive layer that is lower than the portion of the ROX provided below the interconnection.
- Motivation to Combine: Although a single-reference ground, Petitioner argued that to the extent Cederbaum's resistive polysilicon land (31-1) is not considered an "interconnection member," it would have been obvious to modify it. A person of ordinary skill in the art (POSITA) would have been motivated to make the land a low-resistance conductor to reduce the complexity and cost of photolithographic processing steps, a common goal in the industry.
- Expectation of Success: A POSITA would have a high expectation of success in this modification, as Cederbaum itself teaches the alternate processing steps (e.g., silicidation) to make polysilicon lands conductive.

Prior Art Relied Upon: Cederbaum (Patent 5,275,963) and Lee (Patent 4,952,524).
Core Argument for this Ground:
- Prior Art Mapping: This ground addresses dependent claims that specifically recite a "trench isolation." Petitioner asserted that Cederbaum discloses a device with LOCOS-type isolation (its ROX region). Lee explicitly teaches the advantages of using raised shallow trench isolation (STI) instead of older field oxide (LOCOS) methods. Lee's raised STI protrudes above the silicon wafer surface to prevent parasitic channel formation, a known issue with conventional trench processes.
- Motivation to Combine: A POSITA would combine the references because they share the common goal of manufacturing dense, reliable integrated circuits. Petitioner argued that replacing Cederbaum's LOCOS isolation with Lee's superior raised STI was an obvious design choice. This substitution was driven by the well-known industry trend toward STI to achieve miniaturization, consume less chip space, and avoid the "bird's beak" encroachment problem inherent to LOCOS.
- Expectation of Success: A POSITA would have had a reasonable expectation of success. Substituting one known isolation technique (LOCOS) for another, improved one (STI) was a well-understood modification using predictable, standard fabrication techniques. Petitioner highlighted that the PTAB, in a final written decision on a related patent, had already found this exact substitution to be obvious.

Petitioner argued that claim terms should be given their plain and ordinary meaning under the Phillips standard.
The term "formed on" was construed as "formed directly or indirectly on," consistent with an agreement between the parties in related district court litigation. This construction is critical to the argument that Cederbaum's insulating film (PSG layer 26), which is formed over intermediate layers on top of the interconnection, meets the limitation of claim 1.
Petitioner also relied on the doctrine of claim differentiation, arguing that because dependent claim 39 explicitly requires an insulating film formed directly on the interconnection, independent claim 1 must be broader and encompass indirect formation.

Petitioner requested the institution of an inter partes review and cancellation of claims 1-24, 28, 31, 35, 39-40, 44, 47, 51, 55, and 60 of the '409 patent as unpatentable.