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Dec 13th, 2011
Overview of Monolithic 3D Integration solutions for 3D flash memories
Here is an article from Deepak Sekar, Chief Scientist of MonolithIC 3D Inc. He presents innovative approaches developed by Toshiba, Samsung, Hynix and Micron for polysilicon-based monolithic 3D flash memories as well as his company's monocrystalline silicon solution.
You can argue about when NAND flash scaling will end. Some people say two years, others say five. However, there is little argument that a monolithic 3D solution is required when conventional NAND flash scaling ends. Figure 1 shows Monolithic 3D NAND flash memory approaches pursued by Toshiba, Samsung, Hynix and Macronix.
Fig 1: Today's polysilicon-based Monolithic 3D NAND Flash Memories
Fig 2: The Ion-Cut process can provide stacked single crystal silicon at low thermal budget.
Ion-cut, the technology used for manufacturing all SOI wafers nowadays, can provide stacked single-crystal silicon at low thermal budgets. Its shown in Figure 2. Ion-cut involves bonding a hydrogen implanted top layer wafer onto a bottom layer wafer, cleaving the bonded stack at its hydrogen implant plane and later polishing the surface. This process was invented in the early 1990s at CEA -LETI and has been in production since the late 1990s.The process costs around $60 per layer of memory, which is affordable. Ion-cut will become a public-domain technology in 2012, when its basic patent expires. For more cost information on ion-cut, please see my old blog post: How much does ion-cut cost?
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