Kye-Hyun Kyung

A 1.2 V 12.8 GB/s 2 Gb Mobile Wide-I/O DRAM With 4

Mobile DRAM is widely employed in portable electronic devices due to its feature of low power consumption. Recently, as the market trend renders integration of various features in one chip, mobile DRAM is required to have not only low power consumption but also high capacity and high speed. To attain these goals in mobile DRAM, we designed a 1Gb single data rate (SDR) Wide-I/O mobile SDRAM with 4 channels and 512 DQ pins, featuring 12.8GB/s data bandwidth.

\times

A 1.8 V 700 Mb/s/pin 512 Mb DDR-II SDRAM is JEDEC standard compliant. With the hierarchical I/O line and local sensing, t/sub AA/ /t/sub RCD//t/sub RP/ of 3/3/3 at 533 Mb/s are achieved in the design. For signal integrity at 533 Mb/s, off-chip driver calibration and on-die termination are employed.

128 I/Os Using TSV Based Stacking

This paper describes a 32-bank 1 Gb DRAM achieving 1 Gbyte/s (500 Mb/s/DQ pin) data bandwidth and the access time from RAS of 31 ns at V/sub cc/=2.0 V and 25/spl deg/C. The chip employs (1) a merged multibank architecture to minimize die area; (2) an extended small swing read operation and a single I/O line driving write scheme to reduce power consumption; (3) a self-strobing I/O schemes to achieve high bandwidth with low power dissipation; and (4) a block redundancy scheme with increased flexibility. The nonstitched chip with an area of 652 mm/sup 2/ has been fabricated using 0.16 /spl mu/m four-poly, four-metal CMOS process technology.

A 1.8 V 700 Mb/s/pin 512 Mb DDR-II SDRAM with on-die termination and off-chip driver calibration

A monolithic 64 Gb MLC NAND flash based on 21 nm process technology has been developed. The device consists of 4-plane arrays and provides page size of up to 32 KB. It also features a newly developed asynchronous DDR interface that can support up to the maximum bandwidth of 400 MB/s. To improve performance and reliability, on-chip randomizer, soft data readout, and incremental bit line pre-charge scheme have been developed.

A 32-bank 1 Gb self-strobing synchronous DRAM with 1 GByte/s bandwidth

Todays explosive demand for data transfer is accelerating the development of non-volatile memory with even larger capacity and cheaper cost. Since the introduction of 3D technology in 2014 [1], V-NAND is believed to be a successful alternative to planar NAND and is quickly displacing planar NAND in the SSD market, due to its performance, reliability, and cost competitiveness. V-NAND has also eliminated the cell-to-cell interference problem by forming an atomic layer for charge trapping [2], which enables further technology scaling. However, the etching technology required for creating a channel hole cannot keep up with the market-driven WL stack requirement. Therefore, total mold height reduction is unavoidable and this creates several problems. 1) reduced mold height increases resistance and capacitance for WLs due to the thinner layers being used. 2) channel hole critical dimension (CD) variation becomes problematic because the additional mold stack height aggravates uniformity, thereby producing WL resistance variation. Consequently, read and program performance degradation is inevitable, furthermore their optimization becomes more challenging.

A 21 nm High Performance 64 Gb MLC NAND Flash Memory With 400 MB/s Asynchronous Toggle DDR Interface

As the workload and speed of a computer system increase, both the data bandwidth and capacity of main memory inevitably need to grow. However, the number of slots per channel is limited to maintain high bandwidth, making the capacity requirement difficult to meet. Another problem is that computer systems impose a limit on the supply of power since their power dissipation increases rapidly, where main memories account for roughly 15% of total power consumption. To address these issues, we design a 4Gb DDR3 SDRAM that supports a 1.2V supply voltage and 1.6Gb/s data rate.

7.1 256Gb 3b/cell V-NAND flash memory with 48 stacked WL layers

Most memory-chip manufacturers keep trying to supply cost-effective storage devices with high-performance characteristics such as shorter tPROG, lower power consumption and higher endurance. For many years, every effort has been made to shrink die size to lower cost and to improve performance. However, the previously used node-shrinking methodology is facing challenges due to increased cell-to-cell interference and patterning difficulties caused by decreasing dimension. To overcome these limitations, 3D-stacking technology has been developed. As a result of long and focused research in 3D stacking technology, we succeed in developing 128 Gb 3b/cell Vertical NAND with 32 stack WL layers for the first time, which is the smallest 128 Gb NAND Flash. The die size is 68.9 mm 2, program time is 700 us and I/O rate is 1 Gb/s.

1.2V 1.6Gb/s 56nm 6F 2 4Gb DDR3 SDRAM with hybrid-I/O sense amplifier and segmented sub-array architecture

We have developed a new 3-bit programming algorithm of high performance TLC(Triple-level-cell, 3-bit/cell) NAND flash memories for 20nm node and beyond. By using the proposed 3-bit algorithm based on reprogramming with SLC-to-TLC migration, performance and BER is improved by 50% and 68%, respectively, compared to conventional method. The proposed algorithm is successfully implemented in 21nm 64Gb TLC NAND flash product that provides 8MB/s write and 400MB/s read throughputs.

A 128 Gb 3b/cell V-NAND Flash Memory With 1 Gb/s I/O Rate

Most memory-chip manufacturers keep trying to supply cost-effective storage devices with high-performance characteristics such as smaller tPROG, lower power consumption and longer endurance. For many years, every effort has been made to shrink die size to lower cost and to improve performance. However, the previously used node-shrinking methodology is facing challenges due to increased cell-to-cell interference and patterning difficulties caused by decreasing dimension. To overcome these limitations, 3D-stacking technology has been developed. As a result of long and focused research in 3D stacking technology, 128Gb 2b/cell device with 24 stack WL layers was announced in 2014 [1].

A new 3-bit programming algorithm using SLC-to-TLC migration for 8MB/s high performance TLC NAND flash memory

Providing both low cost and high storage capacity by means of device scaling and multi-level cell has been a fundamental feature in developing of NAND flash memory to meet an ever-growing flash market. Recently, however, a high speed interface like DDR (Double Data Rate) was newly adopted in NAND flash to satisfy the requirement of emerging market such as SSD (Solid-State Disk) application where high read and write throughputs are demanded [1]. In addition, as NAND scaling further, a portion of data loading and data out times in overall NAND flash performance has been increased due to increasing page size from 2K to 8K bytes, and even up to 16K bytes at two-plane operation. It significantly affects overall performance degradation in not only SSD but also conventional flash card system. The high speed interface in NAND flash, however, causes to increase chip size because of multiple memory planes more than two and additional signal buses [1]. Therefore, a high speed data interface capability with minimized chip size penalty is required in DDR NAND flash. This paper presents 159mm2 32Gb MLC NAND flash which is capable of 200MB/s read and 12MB/s write throughputs in a 32nm technology.