Alpha and Omega Semiconductor Limited, et al. v. Force MOS Technology Co., Ltd., et al.

CourtDistrict Court, N.D. California
DecidedApril 13, 2026
Docket5:22-cv-05448
StatusUnknown

This text of Alpha and Omega Semiconductor Limited, et al. v. Force MOS Technology Co., Ltd., et al. (Alpha and Omega Semiconductor Limited, et al. v. Force MOS Technology Co., Ltd., et al.) is published on Counsel Stack Legal Research, covering District Court, N.D. California primary law. Counsel Stack provides free access to over 12 million legal documents including statutes, case law, regulations, and constitutions.

Bluebook
Alpha and Omega Semiconductor Limited, et al. v. Force MOS Technology Co., Ltd., et al., (N.D. Cal. 2026).

Opinion

1 2 3 4 UNITED STATES DISTRICT COURT 5 NORTHERN DISTRICT OF CALIFORNIA 6 7 ALPHA AND OMEGA Case No. 22-cv-05448-PCP SEMICONDUCTOR LIMITED, et al., 8 Plaintiffs, ORDER RE: MOTIONS FOR 9 SUMMARY JUDGMENT AND TO v. STRIKE 10 FORCE MOS TECHNOLOGY CO., LTD., Re: Dkt. Nos. 149, 159, 172 11 et al., Defendants. 12 13 This case involves a set of patents related to metal oxide semiconductor field effect 14 transistors, or MOSFETs. Now before the Court are several motions. For the reasons stated herein, 15 the Court grants plaintiff Alpha and Omega Semiconductor Ltd.’s (AOS) motion for a summary 16 judgment that its accused products do not infringe U.S. Patent No. 7,646,058. The Court grants 17 defendant Force MOS Technology Co., Ltd.’s motion for summary judgment as to AOS and third- 18 party defendant Jireh Semiconductor, Inc.’s marking defenses under 35 U.S.C. § 287(a) and 19 denies AOS’s motion for summary judgment as to that defense. The Court grants in part and 20 denies in part Force MOS’s motion to exclude certain documents and theories that AOS allegedly 21 failed to disclose during discovery and to strike expert testimony relying on those undisclosed 22 materials.1 23 BACKGROUND 24 As described in greater detail in the Court’s claim construction order, see Dkt. No. 94 at 1– 25 3, MOSFETs are devices composed of differently doped semiconductor materials arranged to 26 27 1 The Court will resolve the parties’ Daubert motions (Dkt. Nos. 161, 163, and 165) and 1 form junctions that, along with conductor and insulator materials, can be used to switch the 2 direction of or amplify electrical signals. Power MOSFETs are designed to handle significant 3 current and voltage and, like other transistors, have three electrical leads or terminals: a source, a 4 drain, and a gate. Applying a voltage to the gate terminal controls the conductivity between the 5 source and drain terminals. In a trench power MOSFET, current flows vertically from the source 6 on the top layer of a silicon chip to the drain on the bottom, controlled by gates located in 7 “trenches” within the chip. 8 Force MOS is the owner of three patents pertaining to various inventions that aim to make 9 power MOSFETs better, smaller, and cheaper. The first, U.S. Patent No. 7,629,634 (“’634 10 patent”), involves a trench MOSFET where the source contacts are trenched in addition to the 11 gates and metal contact plugs extend into the source-contact trenches. The ’634 patent describes 12 the use of particular contact layers at the side walls of those trenches to improve the performance 13 of the chip. The second, U.S. Patent No. 7,847,346 (“’346 patent”), proposes a new source contact 14 trench structure to allow for greater cell density and lower resistance, as well as lower fabrication 15 costs. The third, U.S. Patent No. 7,646,058 (’058 patent”), seeks to improve the heat dissipation of 16 trenched MOSFETs. This patent proposes a wider contact area between the front metal atop the 17 chip and the wires that facilitate external connection, as well as using metals with better thermal 18 conductivity than those used in the prior art. Specifically, claim 1 of the ’058 patent requires that 19 “said metallic contact plugs and said front metal are composed of a metallic material having a 20 thermal conductivity higher than a thermal conductivity of aluminum and/or aluminum alloys.” 21 Force MOS and AOS both make trench MOSFETs, and Force MOS has sold MOSFETs 22 embodying the asserted patents since 2017. In September 2022, Force MOS sent a letter to AOS 23 asserting that AOS’s products infringe the ’634 patent. Soon thereafter, AOS filed this action 24 seeking a declaratory judgment that its accused products do not infringe the ’634 patent. Force 25 MOS sent another letter asserting infringement of the ’346 patent in November 2022, prompting 26 AOS to amend its complaint to seek a declaration that its accused products also do not infringe 27 1 that patent.2 Force MOS then sent a final letter in April 2023 notifying AOS of its alleged 2 infringement of the ’058 patent. Force MOS subsequently filed counterclaims against AOS and a 3 third-party complaint against AOS’s wholly-owned subsidiary Jireh, asserting claims for 4 infringement of the ’646, ’346, and ’058 patents. 5 AOS now moves for summary judgment on Force MOS’s claim for infringement of the 6 ’058 patent and on AOS’s marking defense as to all of Force MOS’s claims. Force MOS moves 7 for summary judgment as to both AOS and Jireh’s marking defenses. Force MOS also moves to 8 strike or exclude certain evidence, information, and expert testimony reliant thereon pursuant to 9 Federal Rule of Civil Procedure 37(c)(1). 10 LEGAL STANDARDS 11 Courts may grant summary judgment “if the movant shows that there is no genuine dispute 12 as to any material fact and the movant is entitled to judgment as a matter of law.” Fed. R. Civ. P. 13 56(a). A factual dispute is genuine “if the evidence is such that a reasonable jury could return a 14 verdict for the nonmoving party.” Anderson v. Liberty Lobby, Inc., 477 U.S. 242, 248 (1986). A 15 dispute is material if it “might affect the outcome of the suit under the governing law.” Id. The 16 moving party bears the initial burden to demonstrate a lack of genuine factual dispute. Celotex v. 17 Catrett, 477 U.S. 317, 323 (1986). “When the nonmoving party has the burden of proof at trial, the 18 moving party need only point out ‘that there is an absence of evidence to support the nonmoving 19 party’s case.” Devereaux v. Abbey, 263 F.3d 1070, 1076 (9th Cir. 2001) (quoting Celotex Corp., 20 477 U.S. at 325). The burden then shifts to the nonmoving party to “provide affidavits or other 21 sources of evidence that ‘set forth specific facts showing that there is a genuine issue for trial.’” Id. 22 at 1076 (quoting Fed. R. Civ. P. 56(e)). “The evidence of the non-movant is to be believed, and all 23 justifiable inferences are to be drawn in his favor.” Anderson, 477 U.S. at 255. 24 Federal Rule of Civil Procedure 37(c)(1) authorizes courts to strike or exclude evidence or 25 information that “a party fails to provide … as required” in its initial disclosures and discovery 26 responses, “unless the failure was substantially justified or is harmless.” This “self-executing, 27 1 automatic sanction … provide[s] a strong inducement for disclosure of material” and does not 2 “require[] … a finding of willfulness or bad faith to exclude … evidence.” Hoffman v. Constr. 3 Protective Servs., Inc., 541 F.3d 1175, 1180 (9th Cir. 2008) (quoting Yeti by Molly, Ltd. v. 4 Deckers Outdoor Corp., 259 F.3d 1101, 1106 (9th Cir. 2001)). The burden is on the party facing 5 discovery sanctions under Rule 37(c)(1) to prove harmlessness or substantial justification. See 6 Torres v. City of Los Angeles, 548 F.3d 1197, 1213 (9th Cir. 2008). A district court generally “has 7 wide discretion in controlling discovery,” and “that discretion is particularly wide when it comes 8 to excluding [evidence] under Rule 37(c)(1).” Ollier v. Sweetwater Union High Sch. Dist., 768 9 F.3d 843, 862 (9th Cir.

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Bluebook (online)
Alpha and Omega Semiconductor Limited, et al. v. Force MOS Technology Co., Ltd., et al., Counsel Stack Legal Research, https://law.counselstack.com/opinion/alpha-and-omega-semiconductor-limited-et-al-v-force-mos-technology-co-cand-2026.