# How a Special Memory Chip Helps Fix Broken 3D NAND Storage > This patent describes a special content addressable memory (CAM) system that quickly finds and reroutes around defective memory locations in 3D NAND storage using multiple processing units at once. - **Patent:** US 12450117 - **Original title:** Firmware repair for three-dimensional NAND memory - **Owner:** Yangtze Memory Technologies Co - **Granted:** 2025 - **Status:** Active - **Times cited:** 0 - **Field:** semiconductors, consumer_electronics, telecommunications, software, data_storage ## What it does The patent describes a Content Addressable Memory (CAM) system designed to repair memory, specifically 3D NAND. It includes a "CAM register" that stores a "mapping table" (Claim 1). This table holds "first addresses" (defective locations, Claim 8) and "second addresses" (redundant, working locations, Claim 9). The system has "N comparators" that check "N input signals" from "N microcontroller units" against the "first addresses" in the table (Claim 1). If a comparator finds a match (meaning a requested address is defective), it sends an "output enablement signal" (Claim 2, 4) to one of "N multiplexers". These multiplexers then use the mapping table to output a "second address" (the redundant, working location) instead of the defective one (Claim 1, 3). For example, if a microcontroller unit tries to read data from a memory page marked as defective, the CAM quickly identifies it and redirects the read operation to a spare, working page. ## What it does NOT cover - CAM systems that do not use N comparators and N multiplexers working in parallel with N microcontroller units (Claim 1). - Memory repair systems that do not rely on a mapping table of first (defective) and second (redundant) addresses (Claim 1, 8, 9). - CAMs used for general data lookup or caching without the specific purpose of identifying and remapping defective memory locations (Claim 6, 8, 9). - Memory devices that are not 3D NAND memory, as implied by the patent's context and Claim 10. - Repair mechanisms that don't involve comparing input addresses to a stored list of defective addresses. ## The clever bit The novelty lies in integrating multiple comparators and multiplexers with a shared CAM register to enable parallel defect detection and address remapping for N simultaneous memory operations. This allows for very fast, concurrent repair decisions, critical for high-speed memory access. ## Real-world examples 1. Solid-state drives (SSDs) 2. Smartphone internal storage 3. Data center storage arrays 4. USB flash drives 5. Embedded memory in IoT devices ## Why it matters Modern memory devices, especially 3D NAND, can have manufacturing defects. This patent describes a way to quickly identify and work around these defects, improving the reliability and yield of memory chips. By using multiple comparators and multiplexers, it can handle several memory operations simultaneously, which is crucial for the high performance required in solid-state drives (SSDs) and other data storage. ## Frequently asked questions ### What does How a Special Memory Chip Helps Fix Broken 3D NAND Storage cover? This patent describes a special content addressable memory (CAM) system that quickly finds and reroutes around defective memory locations in 3D NAND storage using multiple processing units at once. ### Who owns patent US 12450117? Yangtze Memory Technologies Co owns this patent, granted in 2025. ### When does this patent expire? This patent is expected to expire on December 4, 2043, when the invention enters the public domain. ### What problem does this patent solve? Modern memory devices, especially 3D NAND, can have manufacturing defects. This patent describes a way to quickly identify and work around these defects, improving the reliability and yield of memory chips. By using multiple comparators and multiplexers, it can handle several memory operations simultaneously, which is crucial for the high performance required in solid-state drives (SSDs) and other data storage. ### What does this patent NOT cover? CAM systems that do not use N comparators and N multiplexers working in parallel with N microcontroller units (Claim 1). **Full plain-English explainer:** https://patentbrief.org/patent/us/12450117/firmware-repair-for-three-dimensional-nand-memory **Original patent:** https://patents.google.com/patent/US12450117 --- _Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._ ## Related patents Semantically similar inventions in the PatentBrief corpus: - [How 3D Memory Chips Fix Tiny Flaws to Keep Working](https://patentbrief.org/patent/us/9263111/sub-block-disabling-in-3d-memory) — Micron's 2016 patent describes how 3D NAND memory chips can identify and turn off small, defective sections (sub-blocks) to extend the life of the entire memory block, rather than discarding the whole chip. - [How to Precisely Erase Data in 3D NAND Flash Memory](https://patentbrief.org/patent/us/12142328/erasing-and-erasing-verification-for-three-dimensional-nand-memory) — This patent describes a two-stage method for erasing data in 3D NAND memory, using a coarse erase followed by a fine-tuned erase based on multiple sub-verifications to ensure data is completely and efficiently removed. - [How to Program 3D Layered Memory Chips More Precisely](https://patentbrief.org/patent/us/9947413/method-of-initializing-and-programming-3d-non-volatile-memory-device) — This patent describes a method for precisely programming the control transistors and memory cells in advanced 3D non-volatile memory chips, ensuring reliable data storage in stacked layers. - [How to Prepare 3D Flash Memory for Use](https://patentbrief.org/patent/us/9685235/method-of-initializing-3d-non-volatile-memory-device) — This patent describes a method for setting up a 3D non-volatile memory chip, like those in SSDs, by precisely programming control transistors, including a special "dummy" one, to make sure the memory works correctly. - [How NAND Flash Memory Adjusts to Cold Temperatures](https://patentbrief.org/patent/us/10019188/storage-devices-memory-systems-and-operating-methods-to-suppress-operating-error) — This patent describes a method for NAND flash memory systems to prevent errors by automatically adjusting their operating conditions, like data speed or voltage, when the temperature drops too low.