美光3D NAND，技术路线图

Core Viewpoint - Micron Technology presented its latest 3D NAND flash technology, the ninth generation (G9), at the 2025 IEEE International Memory Workshop, highlighting significant advancements in storage density and data transfer speeds while maintaining the same storage capacity per chip as the previous generation [1]. Summary by Sections G9 3D NAND Flash Technology - The G9 3D NAND flash has a storage capacity of 1 Tbit per chip, the same as the G8, but with a 40% increase in storage density of the memory cell array and a 30% increase in chip storage density [1]. - The maximum data transfer speed of G9 has improved by 1.5 times compared to G8 [1]. - The number of word line layers in G9 is 276, only a 19% increase from the 232 layers in G8, indicating that innovations beyond just increasing layer count contributed to the density improvements [1]. Storage Density Improvements - The storage density of Micron's memory cell array increased from 17 Gbit/mm² in G7 to 25 Gbit/mm² in G8, and further to 35 Gbit/mm² in G9 [3]. - Innovations include the removal of virtual pillars, which reduced block height by approximately 14%, and a decrease in the number of page buffers from 16 in G8 to 6 in G9, halving the page buffer's chip area [3]. Future Technology Challenges - The future of 3D NAND flash technology, including G10 and beyond, will face increasing technical challenges, akin to climbing an infinitely long spiral staircase [5]. - The introduction of "Confined SN" technology aims to reduce interference between adjacent cells, resulting in a 10% reduction in programming time and a 50% decrease in coupling capacitance between adjacent cells [9]. Innovations and Solutions - The G9 stack height exceeds 13 μm, with a layer height of 6.5 μm, and a high aspect ratio of over 43 due to the small diameter of storage holes [7]. - To mitigate electrical interference, Micron introduced air gaps in the insulation film and limited the nitrogen film to the gate side of the cell transistors [7][8]. - The transition from charge trapping to ferroelectric polarization is proposed as a solution to reduce the risk of dielectric breakdown, which is critical as the number of layers increases [16]. Cost and Performance Considerations - Micron is exploring wafer bonding technology to optimize the performance of peripheral circuits and memory cell arrays, despite the initial increase in costs associated with wafer bonding [12]. - The cost of wafer bonding is expected to decrease with each new technology generation, potentially becoming more cost-effective than single-chip manufacturing in the future [12][14].