Micron Technology has accused Chinese memory-chip maker Yangtze Memory Technologies Co. (YMTC) of recruiting engineers with access to confidential Micron technology, using that know-how to develop its own chips and patents, and later asserting one of those patents against Micron.
The allegations are part of a 103-page lawsuit Micron filed Sept. 15 in the U.S. District Court for the District of Idaho against YMTC and former Micron engineer Hongbin Zhu.
Micron alleges that some departing engineers concealed where they were going. Several told the company they were leaving for family reasons before later working for or with YMTC, according to the complaint.
Micron says YMTC used its trade secrets and confidential information to help develop its 64-layer, 128-layer, and 232-layer 3D NAND chips—successive generations of flash memory in which manufacturers stack more memory cells vertically to increase capacity.
In an Oct. 5 statement to The Epoch Times, Micron accused YMTC of “stealing Micron’s trade secrets, which YMTC then incorporated into its patent portfolio.”
YMTC did not respond to requests for comment.
Patent Lawsuit Against Micron
One of the patents at the center of Micron’s case names Daesik Song, a former Micron design engineer, as an inventor.
Song’s public LinkedIn profile lists Micron employment through February 2017 and YMTC beginning the same month.
Micron alleges that Song worked on confidential circuitry used to move data into and out of memory chips while he was at Micron from 2008 to 2017.
The complaint says Song authored a confidential Micron presentation in 2016 dealing with that circuitry. It also says his employment agreement required him to assign certain inventions developed during his Micron employment to the company.
Two years after Song left Micron, YMTC filed for a U.S. patent naming him as an inventor.
That patent, U.S. Patent No. 10,707,851, was later asserted by YMTC against Micron in a 2025 infringement lawsuit in Texas.
Micron says the patent covers technology related to work Song had done at Micron and is asking the Idaho court to declare that Micron owns or co-owns it.
Micron is also seeking ownership or co-ownership of three other U.S. patents assigned to YMTC—Nos. 10,566,336, 11,049,866, and 11,532,636. Those three name Zhu among their inventors.
The complaint makes similar allegations involving other former Micron employees and YMTC patents.
Wider Patent Fight
The Idaho lawsuit comes amid a broader patent fight between the two companies.
Since 2023, YMTC has brought patent cases against Micron in the United States and China, according to Micron’s regulatory filings. The dispute later expanded to Britain and Germany.
The fight produced a new development in Germany last month. On Sept. 18, the Munich I Regional Court issued injunctions against Micron in disputes involving two YMTC German utility models tied to 3D NAND technology. Micron has challenged the rulings.
Those German cases involve different intellectual property rights from the four U.S. patents Micron is claiming in Idaho.
Parts of Micron’s Idaho complaint remain sealed, because they contain details about its chip manufacturing processes.
U.S. Magistrate Judge Debora Grasham found that the sealed material appeared to contain confidential business information whose public disclosure could harm Micron’s competitive interests. The judge’s ruling did not decide whether YMTC had misappropriated that information.
The Epoch Times also asked YMTC to forward questions to Zhu, Song, Jun Liu, Yushi Hu, Qian Tao, Wenxi Zhou, and Hua Tan, seeking confirmation of their relationships with YMTC and responses to Micron’s allegations. YMTC did not respond to that request.
Liu’s public LinkedIn profile still lists him working for Micron in Boise, although Micron’s complaint says he left the company on June 9, 2017, and subsequently worked for or with YMTC.
In the latest docket reviewed by The Epoch Times, dated Oct. 2, YMTC and Zhu had not filed a response to Micron’s complaint.
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