Qualcomm Inc v. Monterey Research LLC

1. Case Identification

• Case #: IPR2021-00125
• Patent #: 6,642,573
• Filed: October 30, 2020
• Petitioner(s): Qualcomm Incorporated
• Patent Owner(s): Monterey Research, LLC
• Challenged Claims: 1-2, 4, 7-22

2. Patent Overview

• Title: Use of High-K Dielectric Material in Modified ONO Structure For Semiconductor Devices
• Brief Description: The ’573 patent discloses semiconductor memory devices, such as non-volatile EEPROM cells, having a modified oxide-nitride-oxide (ONO) gate stack structure. The purported invention is replacing one or both of the conventional silicon dioxide layers in the ONO structure with a "composite dielectric material" having mid-K or high-K (high dielectric constant) properties to address leakage current and other challenges associated with device scaling.

3. Grounds for Unpatentability

Ground 1: Obviousness over Chang and Chooi - Claims 1, 4, 8-11, 16-20, and 22 are obvious over Chang in view of Chooi.

• Prior Art Relied Upon: Chang (Patent 6,461,949) and Chooi (Application # 2002/0064970).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Chang taught the fundamental structure of a non-volatile memory (NROM) device comprising a modified ONO structure, which serves as the charge storage layer. Critically, Chang disclosed replacing the traditional top silicon oxide layer with a high-K material (tantalum pentaoxide) to improve the device's coupling ratio and reduce control gate voltage, addressing known problems with silicon oxide. Chooi disclosed a superior "composite hafnium oxide-silicon oxide" material, which has mid-K to high-K properties and is explicitly designed to replace thermal silicon dioxide in gate dielectrics. Petitioner asserted this combination met all limitations of the independent claims, including the requirement for a "composite dielectric material" comprising elements of a high-K material (hafnium oxide).
  • Motivation to Combine: A POSITA would combine Chooi with Chang to improve Chang's device. The primary motivation was to replace Chang's tantalum pentaoxide layer with Chooi's superior composite hafnium oxide-silicon oxide. Chooi explicitly identified problems with tantalum pentaoxide, such as crystallization, and taught that its composite material overcame such shortcomings. Both references addressed the same well-known problem of replacing silicon dioxide to improve device performance, making the substitution of one proposed high-K solution (Chooi's) for another (Chang's) an obvious design choice for improved results.
  • Expectation of Success: A POSITA would have a reasonable expectation of success because Chooi taught that its deposition process for the composite material was compatible with a variety of substrates, including the silicon and silicon nitride layers present in Chang's ONO structure. The combination was a predictable substitution of one insulating dielectric for another to achieve known benefits.

Ground 2: Obviousness over Ohmi and Chooi - Claims 1-2, 7-15, and 20-21 are obvious over Ohmi in view of Chooi.

• Prior Art Relied Upon: Ohmi (Patent 6,669,825) and Chooi (Application # 2002/0064970).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner contended that Ohmi disclosed a conventional floating gate flash memory device with a stacked gate structure, including an ONO layer that functions as the interpoly dielectric. Ohmi's ONO layer used conventional silicon oxide films, and Ohmi expressly recognized the problem that these layers needed to be thick to suppress leakage current, which in turn required undesirably high operating voltages. This established the baseline device and the problem to be solved. As in Ground 1, Chooi provided the solution by teaching a composite hafnium oxide-silicon oxide material to replace silicon dioxide, thereby meeting the claim limitations for a composite mid-K or high-K layer.
  • Motivation to Combine: A POSITA would combine Chooi's material with Ohmi's device to solve the exact problem Ohmi identified. Ohmi stated a need for a high-quality insulation film that allows for small thickness without high leakage current. Chooi directly addressed this by teaching the replacement of silicon dioxide, which faces scaling limits due to tunneling current, with a higher-K composite material. A POSITA would have been motivated to substitute Chooi’s composite material for one or both of the silicon oxide layers in Ohmi’s ONO structure to reduce layer thickness, improve the coupling ratio, and lower operating voltages, all of which were well-known goals in the field.
  • Expectation of Success: The combination was expected to succeed because Chooi’s deposition process was versatile and taught application onto silicon and silicon nitride, the materials adjacent to the oxide layers in Ohmi's ONO stack. The substitution would have yielded the predictable advantages associated with higher-K dielectrics.

4. Key Claim Construction Positions

• "Composite dielectric material": Petitioner argued this term should be construed consistent with the patent’s specification, which defined it as a material comprising elements of at least two other dielectric materials. Critically, the specification stated it may be formed by "co-deposition of its component elements, or by sequential deposition followed by a treatment step." This construction was central because the patent was allowed during prosecution only after the claims were amended to include "composite" material, which the applicant argued distinguished the invention from prior art that merely stacked two separate layers. Chooi was argued to disclose such a true, co-deposited composite material (hafnium oxide-silicon oxide).
• "High-K dielectric material": Petitioner adopted the patent's explicit definition of a material with a K value of about 20 or more.

5. Arguments Regarding Discretionary Denial

• Petitioner argued that the grounds presented were not cumulative of art considered during the original prosecution. Although the examiner had previously considered combinations of an ONO structure with a high-K material, the prior art of record (e.g., Wallace, Gardner, Sun) was overcome by the applicant’s argument that those references did not disclose a "true composite layer." Petitioner asserted that the newly cited Chooi reference cured this deficiency by explicitly teaching a co-deposited composite hafnium oxide-silicon oxide layer, directly addressing the dispositive issue that led to the patent's allowance. Therefore, the petition raised new issues that were not before the examiner.

6. Relief Requested

• Petitioner requested institution of an inter partes review and cancellation of claims 1-2 and 7-22 of the ’573 patent as unpatentable under 35 U.S.C. §103.