Micron Technology has scored another win in its long-running intellectual property fight with China’s Yangtze Memory Technologies Co. (YMTC). The U.S. Patent Trial and Appeal Board (PTAB) has invalidated the challenged claims of U.S. patent US 12,010,838, related to structures used in 3D NAND memory. With this decision, handed down in early September 2026, Micron brings its tally to seven YMTC patents struck down in proceedings before the U.S. agency.
The Micron-YMTC patent battle in 20 seconds
- The PTAB has invalidated the challenged claims of YMTC’s US 12,010,838 patent.
- The patent describes a staircase structure used to make connections in 3D NAND memory.
- It’s the seventh YMTC patent Micron has managed to knock down in proceedings before the PTAB.
- The decision doesn’t resolve the whole dispute: both companies still have intellectual property fights pending in the United States, China, and Europe.
- YMTC can appeal adverse decisions to the Court of Appeals for the Federal Circuit.
The new ruling matters for more than just the win tally. Micron and YMTC have been clashing since 2023 over technologies at the heart of 3D NAND memory manufacturing, right as the Chinese company keeps growing its weight in the global market.
The latest available figures show just how much the competitive picture has shifted. In the second quarter of 2026, YMTC reached roughly a 14% share of the NAND market, up from 9% a year earlier, while Micron sat around 15%. Those numbers put the two companies far closer together than would have seemed possible just a few years ago.
The legal fight is also playing out against a backdrop shaped by U.S. technology restrictions on China and Beijing’s push to build a semiconductor supply chain less dependent on foreign suppliers.
The patent YMTC just lost explains a 3D NAND memory problem
Patent US 12,010,838, titled Staircase Structure for Memory Device, was granted to YMTC on June 11, 2024.
To understand why it matters, it helps to look at how today’s NAND memory is built.
Instead of placing memory cells only on a flat surface, manufacturers are stacking more and more layers vertically. The more layers you can pack in, the more data you can store within a given footprint.
But adding more layers creates another problem: you have to electrically connect the memory’s different internal lines.
One solution is to build a structure that looks like a microscopic staircase. Each step provides access to certain conductive layers through electrical contacts.
YMTC’s patent covers a specific configuration of that structure, and in particular the arrangement of what are called landing pads, the areas where connections can later be made.
The proceeding’s documentation describes a configuration in which one of the side surfaces of the landing pad is in contact with an insulating layer, while another is laterally offset from the conductive layer beneath it.
Micron argued those features didn’t amount to a sufficiently distinct invention over prior technology.
The U.S. chipmaker submitted prior art, including patents identified during the proceeding as Kim, Lee, Yang, Haller, and Park, to argue that the claims were obvious in light of previously existing knowledge.
Micron used a PGR instead of waiting for the usual process
This patent’s procedural path has a wrinkle.
Micron initially filed an inter partes review (IPR) petition, registered as IPR2025-00229, but the patent had been granted too recently for that process to apply.
U.S. law sets time restrictions barring an IPR request during the first nine months after certain patents are granted.
Micron then withdrew that petition and proceeded instead through a Post-Grant Review (PGR), another PTAB process designed specifically to review recently granted patents.
The case was registered as PGR2025-00021.
The PTAB authorized the review on September 3, 2025, after finding that Micron had initially shown a sufficient likelihood that at least one of the challenged claims would be found unpatentable.
Micron had requested review of claims 1, 3 through 7, and 12 through 20 of the patent.
The strategy leaned mainly on Section 103 of U.S. patent law, which covers obviousness. In simplified terms, a patent can lose protection if what it claims would have been obvious to someone skilled in the field, based on prior technology.
The process has now concluded with a ruling against YMTC on the challenged claims.
But that doesn’t mean the patent disappears immediately from every possible legal discussion. Final PTAB decisions can be appealed to the U.S. Court of Appeals for the Federal Circuit, and YMTC is already pursuing that route in other proceedings involving Micron.
Seven patents invalidated, but the fight is much bigger
Talking about a seventh win might give the impression that Micron is close to closing out the dispute. The reality is a lot more complicated.
Court filings reveal a patent campaign of unusual scale.
YMTC filed a lawsuit against Micron in the Northern District of California in November 2023, accusing it of infringing eight U.S. patents through certain 3D NAND products.
A second lawsuit followed in July 2024, adding eleven patents related to 3D NAND and DDR5 DRAM products.
Micron responded by attacking the validity of the patents before the PTAB. The proceeding’s own documentation notes it went on to file 26 petitions against 19 YMTC patents and 251 claims.
The conflict kept growing.
On October 6, 2025, YMTC opened another international front. According to regulatory filings from Micron, the Chinese company launched additional proceedings in the United States, the United Kingdom, and Germany.
In the Eastern District of Texas, it accused certain Micron products of infringing seven patents related to 3D NAND and another tied to LPDRAM. It also filed a lawsuit before the UK’s High Court, three proceedings before the Düsseldorf division of the Unified Patent Court (UPC), and five lawsuits before the Munich Regional Court.
China is another front altogether.
YMTC has filed proceedings in intellectual property courts in Beijing and Shanghai related to the importation and sale of Micron’s NAND and SSD products.
So the confrontation has stopped being a single U.S. lawsuit and become an international dispute over foundational memory technologies.
The PTAB has become central to Micron’s defense
Micron’s U.S. strategy also shows why the PTAB carries so much weight in major tech litigation.
When a company is sued for infringement, it can defend itself by arguing its product doesn’t use the patented technology. But it can also go straight at the patent itself and try to show it never should have been granted in those terms.
Micron is leaning heavily on that second approach.
By getting certain claims declared unpatentable, it strips away legal ammunition YMTC could use in the parallel litigation.
The wins haven’t been across the board, though.
For example, in IPR2025-00118, involving patent US 10,879,164, the PTAB ruled in June 2026 that Micron hadn’t shown that the 14 challenged claims were unpatentable.
In other cases, the outcome has been mixed. In July, in IPR2025-00191 over patent US 11,581,322, the PTAB found claims 3, 8, 11, 12, and 19 unpatentable, but upheld eleven of the other challenged claims.
That’s why the “seven wins” tally needs context. It doesn’t mean Micron has won every proceeding, or that YMTC has lost every patent it’s using against its rival.
From the courtroom to head-to-head competition in the NAND market
This battle’s commercial stakes keep growing because YMTC is no longer a marginal player in the NAND market.
The Chinese company has developed successive generations of 3D NAND memory using its Xtacking architecture and keeps expanding its footprint despite U.S. restrictions. It has also been on the U.S. Commerce Department’s Entity List since December 2022, which limits its access to certain American technologies.
Micron competes directly in the same market, and its regulatory filings acknowledge that the litigation touches technologies used across a large share of its NAND and DRAM products.
This technology rivalry is unfolding at a particularly strong moment for the memory business. During the second quarter of 2026, NAND market revenue rose roughly 70% year over year, fueled in part by demand tied to AI infrastructure.
That raises the economic value of controlling the technologies used to build denser, faster, and more competitive memory.
The PTAB’s latest decision gives Micron another legal edge within the United States, but it doesn’t close out the fight.
YMTC still holds other patents, has the option to appeal, and keeps proceedings open in multiple jurisdictions. Micron, meanwhile, keeps trying to dismantle the intellectual property portfolio its rival is using against its products.
The seventh patent knocked down confirms a trend, but there’s still a long way to go before knowing who comes out ahead in one of the biggest intellectual property battles currently playing out in the global memory industry.
Frequently Asked Questions
Which YMTC patent has the PTAB just invalidated?
The decision affects the challenged claims of U.S. patent US 12,010,838, related to a staircase structure and landing pads used to make connections in 3D NAND memory devices.
What is the PTAB?
The Patent Trial and Appeal Board is a body within the U.S. Patent and Trademark Office (USPTO) that, among other functions, reviews the patentability of already-granted claims through processes like IPR and PGR.
Does this decision mean Micron has definitively beaten YMTC?
No. It’s a win within a much larger conflict. There are other proceedings before the PTAB, appeals, and litigation between the two companies in the United States, China, and Europe.
Why do these 3D NAND memory patents matter?
Modern NAND memory stacks numerous layers to increase storage density. The patents at stake cover different techniques related to the manufacturing, connection, and operation of those three-dimensional structures.