DCT
5:25-cv-09240
Qorvo Inc v. Denso Corp
Key Events
Complaint
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Qorvo, Inc. (Delaware)
- Defendant: Denso Corporation (Japan); National Institute of Advanced Industrial Science and Technology (AIST) (Japan)
- Plaintiff’s Counsel: Alston & Bird LLP
- Case Identification: 3:25-cv-09240, N.D. Cal., 10/27/2025
- Venue Allegations: Plaintiff alleges venue is proper because Defendants are foreign corporations and because a substantial portion of the events giving rise to the dispute, including infringement allegations and in-person meetings, occurred within the Northern District of California.
- Core Dispute: Plaintiff Qorvo seeks a declaratory judgment that its bulk acoustic wave (BAW) filter products do not infringe two of Defendants' patents related to the specific elemental composition of piezoelectric thin films.
- Technical Context: The technology at issue involves scandium aluminum nitride (ScAlN) thin films, a material critical for manufacturing high-performance radio frequency (RF) filters used in modern wireless communication devices.
- Key Procedural History: The complaint describes an extended period of pre-suit communications, initiated by a November 2023 letter from Denso to Qorvo alleging infringement. These communications included the exchange of claim charts, disputes over the accuracy of Denso's product testing, and multiple in-person and virtual meetings. The complaint also notes that during the prosecution of one of the patents-in-suit, the patentee amended the claims to add a lower threshold for carbon content to overcome a prior art rejection. Additionally, Denso has filed a separate lawsuit against a third party, Skyworks Solutions, Inc., asserting one of the same patents.
Case Timeline
| Date | Event |
|---|---|
| 2007-05-31 | U.S. Patent No. 7,758,979 Priority Date |
| 2010-07-20 | U.S. Patent No. 7,758,979 Issues |
| 2013-05-31 | U.S. Patent No. 9,735,342 Priority Date |
| 2017-08-15 | U.S. Patent No. 9,735,342 Issues |
| 2023-11-29 | Denso sends letter and claim chart to Qorvo alleging infringement |
| 2024-01-25 | Qorvo responds, disputing infringement based on scandium content |
| 2024-04-23 | Denso acknowledges partially incorrect test results |
| 2024-05-03 | Qorvo reiterates issues with Denso's testing methodology |
| 2024-05-09 | Denso reaffirms infringement allegations but concedes some testing was incorrect |
| 2024-06-13 | Denso provides an updated claim chart for the '979 patent |
| 2024-07-19 | Denso and Qorvo hold a virtual meeting |
| 2024-07-25 | Denso provides a list of additional patents, including the '342 patent |
| 2024-08-28 | Denso and Qorvo representatives meet in person in San Jose, CA |
| 2025-06-20 | Denso files a complaint against Skyworks Solutions alleging infringement of the '979 patent |
| 2025-10-27 | Complaint for Declaratory Judgment filed by Qorvo |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 7,758,979 - “Piezoelectric thin film, piezoelectric materials, and fabrication method of piezoelectric thin film and piezoelectric material, and piezoelectric resonator, actuator element, and physical sensor using piezoelectric thin film”
The Invention Explained
- Problem Addressed: The patent’s background section describes that while conventional aluminum nitride (AlN) has desirable properties for RF filters, its piezoelectric constant is low compared to other materials. This limitation necessitates higher operating voltages and impedes device miniaturization and performance improvement (’979 Patent, col. 1:16-56).
- The Patented Solution: The invention addresses this problem by adding a specific amount of scandium (Sc) to the aluminum nitride film. This modification of the material's composition is described as improving the piezoelectric response while maintaining the other beneficial characteristics of AlN, such as high elastic wave propagation speed (’979 Patent, Abstract; col. 3:5-10; Fig. 2).
- Technical Importance: An enhanced piezoelectric response enables the design of smaller, more energy-efficient RF components, a key technological driver for the advancement of portable electronics like mobile phones (’979 Patent, col. 2:51-60).
Key Claims at a Glance
- The complaint identifies independent claim 6 as being in controversy (Compl. ¶39).
- The essential elements of claim 6 are:
- A piezoelectric thin film comprising an aluminum nitride thin containing scandium,
- a content ratio of the scandium being in a range of 10 atom % to 35 atom % or 40 atom % to 50 atom %
- on an assumption that a total amount of a number of atoms of the scandium and a number of atoms of aluminum in the aluminum nitride thin film is 100 atom %.
U.S. Patent No. 9,735,342 - “Piezoelectric thin film and method for producing the same”
The Invention Explained
- Problem Addressed: The patent identifies an issue where scandium aluminum nitride films produced by sputtering exhibit significant variation in their piezoelectric properties. The inventors determined that contamination from carbon atoms during the manufacturing process is a cause of this performance degradation (’342 Patent, col. 5:36-44).
- The Patented Solution: The invention is a ScAlN piezoelectric thin film defined by having a very low, controlled amount of carbon (2.5 atomic % or less). The patent also discloses methods for reliably producing such films, for example by using a sputtering target with a low carbon content, thereby ensuring consistently high piezoelectric performance (’342 Patent, Abstract; col. 5:55-68).
- Technical Importance: By controlling for carbon impurities, the invention provides a method for reliably and consistently manufacturing high-performance ScAlN films, which is critical for commercial-scale production and quality control of advanced RF components (’342 Patent, col. 5:44-50).
Key Claims at a Glance
- The complaint identifies independent claim 1 as being in controversy (Compl. ¶47).
- The essential elements of claim 1 are:
- A piezoelectric thin film that is formed through sputtering and consists essentially of scandium aluminum nitride,
- wherein the piezoelectric thin film has a carbon atomic content between 0.1 at % and 2.5 at %.
III. The Accused Instrumentality
Product Identification
- The complaint identifies two sets of accused products. The "Accused Scandium Products" are certain Qorvo BAW filters, including models EG2516, EG2538, EG2539, EG2800, EG2801, EG2804, EG2805, and EG9128, which are accused of infringing the ’979 Patent (Compl. ¶39). The "Accused Carbonless Products" are a different set of Qorvo filters, including models EG2625 and EG2812, which are accused of infringing the ’342 Patent (Compl. ¶47, p. 8:1-2).
Functionality and Market Context
- The accused products are bulk acoustic wave (BAW) filters, which are semiconductor components used in radio frequency applications (Compl. ¶¶ 4, 27). The complaint alleges that these filters are specifically designed and manufactured to contain precise elemental compositions that fall outside the ranges claimed in the patents-in-suit (Compl. ¶¶ 41-43, 49-50). Qorvo is positioned in the complaint as a "leading global provider" of such solutions for large markets, including consumer electronics, indicating the commercial significance of these products (Compl. ¶4).
IV. Analysis of Infringement Allegations
No probative visual evidence provided in complaint.
’979 Patent Infringement Allegations
| Claim Element (from Independent Claim 6) | Alleged Non-Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| a content ratio of the scandium being in a range of 10 atom % to 35 atom % or 40 atom % to 50 atom %... | The complaint alleges that the Accused Scandium Products are purposefully designed to have, and consistently include, a scandium content ratio of less than 10 atom %. Specifically, certain "Sc6" filters are alleged to contain 6.4±0.3 atom % scandium, and certain "Sc9" filters are alleged to contain 9.5±0.3 atom % scandium. | ¶¶ 40-43 | col. 22:28-32 |
- Identified Points of Contention:
- Technical Question: The dispute appears to be primarily factual, centered on the measurement of the scandium content in Qorvo's products. The complaint alleges that Denso's initial testing was flawed and produced "inflated values" (Compl. ¶¶ 11, 13). A central question for the court will be which party's materials-characterization methodology provides the more accurate and reliable measurement of the atomic composition of the thin films.
- Scope Questions: A potential legal dispute may arise over the claim phrase "on an assumption that a total amount of a number of atoms of the scandium and a number of atoms of aluminum... is 100 atom %." The interpretation of this phrase could influence how the "content ratio" is calculated from raw measurement data, raising the question of whether it requires a specific normalization that could alter the final percentage.
’342 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Non-Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| the piezoelectric thin film has a carbon atomic content between 0.1 at % and 2.5 at % | The complaint alleges that the Accused Carbonless Products purposefully and consistently include a carbon atomic content of less than 0.1 atomic %. The complaint further alleges a maximum carbon content of 0.027 atomic %. | ¶¶ 48-50 | col. 9:27-28 |
- Identified Points of Contention:
- Technical Question: As with the ’979 Patent, the core of the dispute is factual: what is the precise carbon atomic content in the accused filters? The case will likely involve conflicting evidence regarding the measurement of trace elements in semiconductor materials.
- Scope Questions: The complaint raises an issue of prosecution history estoppel. It alleges that the patentee added the 0.1 at % lower limit for carbon content specifically to overcome prior art that disclosed films with trace impurities of less than 0.1 wt% (Compl. ¶51). This raises the question of whether the patentee surrendered any claim coverage for films with less than 0.1 at % carbon, which may prevent Defendants from asserting infringement under the doctrine of equivalents.
V. Key Claim Terms for Construction
The Term: "content ratio" (’979 Patent, Claim 6)
Context and Importance: The entire non-infringement argument for the ’979 Patent hinges on whether the measured "content ratio" of scandium in Qorvo's products is below the claimed lower limit of 10 atom %. The construction of this term, particularly in light of the claim's "assumption" clause, will dictate the proper method for calculating the percentage from empirical data.
Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: A party seeking a broader scope might argue that the clause "on an assumption that a total amount of a number of atoms of the scandium and a number of atoms of aluminum in the aluminum nitride thin film is 100 atom %" (’979 Patent, col. 22:30-32) requires normalizing the measurement to only these two elements, effectively ignoring any other trace elements and potentially increasing the calculated scandium percentage.
- Evidence for a Narrower Interpretation: A party seeking a narrower scope could argue that the term refers to a direct measurement using standard industry techniques and that the "assumption" clause is merely a definitional convention for the Sc-Al system, not a mandate to manipulate raw measurement data. The specification discusses experimental results without detailing such a normalization (’979 Patent, Fig. 1).
The Term: "consists essentially of scandium aluminum nitride" (’342 Patent, Claim 1)
Context and Importance: This transitional phrase allows for the presence of unrecited elements that do not materially affect the basic and novel properties of the invention. Here, the patent teaches that carbon is a deleterious impurity, and the claim explicitly sets a permissible range for it. The term's construction is important because Qorvo’s products are alleged to have carbon, but at a level below the claimed range. Practitioners may focus on whether having carbon outside the claimed range means the product as a whole falls outside the scope of what "consists essentially of" the claimed composition.
Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: A party could argue that the phrase allows for impurities and that the separate, explicit limitation on carbon content ("between 0.1 at % and 2.5 at %") is the sole determinant of infringement with respect to carbon.
- Evidence for a Narrower Interpretation: Qorvo may argue that the patent's core teaching is that carbon contamination is precisely what deteriorates the film's novel properties (’342 Patent, col. 5:36-44). Therefore, the "consists essentially of" language reinforces the criticality of the specific, recited carbon range. A film with a carbon content outside that narrow window, even if lower, could be argued to be a different composition that does not have the same basic and novel properties as what was claimed.
VI. Analyst’s Conclusion: Key Questions for the Case
This declaratory judgment action appears to center on three key questions for the court:
- A primary issue will be one of empirical measurement: What are the actual, verifiable atomic percentages of scandium (for the ’979 patent) and carbon (for the ’342 patent) in Qorvo’s accused filters? The resolution will likely depend on the court's assessment of competing expert testimony regarding advanced materials-characterization techniques.
- A key legal question for the ’342 patent will be the impact of the prosecution history: Did the patentee's amendment and arguments adding the "0.1 at %" lower carbon limit to overcome prior art create a clear and unmistakable surrender of claim scope, thereby estopping Defendants from arguing that Qorvo's products with less than 0.1 at % carbon infringe?
- A central question of claim interpretation for the ’979 patent will be how the "content ratio" must be calculated. Does the claim's "assumption" clause prescribe a specific mathematical normalization that differs from a direct measurement, and could the choice of methodology be outcome-determinative?