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High-density 'neither-NOR' type flash storage device and its programming method

A programming method and flash storage technology, applied in the field of flash storage devices, can solve problems such as reducing the overall speed of flash memory

Inactive Publication Date: 2004-09-22
SAMSUNG ELECTRONICS CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] Unfortunately, such a low supply voltage imposes a practical limit on the electrical programming current produced by the pumping circuit of the flash memory
This limitation on the programming current used reduces the overall speed of such a flash memory by limiting the number of flash memory cells that can be programmed simultaneously

Method used

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  • High-density 'neither-NOR' type flash storage device and its programming method
  • High-density 'neither-NOR' type flash storage device and its programming method
  • High-density 'neither-NOR' type flash storage device and its programming method

Examples

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no. 1 example

[0037] refer to image 3 , which shows the relationship between the cell's valve voltage and the varying programming time. exist image 3 In , the vertical axis represents the valve voltage of the flash memory cell, and the horizontal axis represents the programming time represented by a logarithmic value. Assuming that the target valve voltage Vth_pgm to be programmed is 8V, the cell programming time Tcycle required to program the cell is 1 μs. At this time, from image 3 It can be seen from the figure that within 0.5 μs, which is half of the cell programming time Tcycle, the valve voltage Vth of the cell increases to about 7V (close to 85%).

[0038] Such as Figure 4 As shown, it shows the change of valve voltage and cell current with programming time. During the first programming time 0~T1, the valve voltage Vth of the cell increases rapidly to Vth1. At the same time, the cell current flowing through the programming cell at the first programming time Decrease rapidly ...

no. 2 example

[0056] Figure 7 Shown is a block diagram of a NOR type flash memory device according to a second embodiment of the present invention. exist Figure 7 in, with Figure 5The same components are marked with the same reference numerals, and their descriptions are omitted. The second embodiment differs from the first embodiment in that the drain voltage, that is, is supplied to one bit line at the first programming time T1 required to program one flash memory cell to a valve voltage Vth1 lower than the target valve voltage Vth_pgm. The drain voltage is different from the drain voltage supplied to a bit line at a second programming time T2 required to program a flash memory cell to a valve voltage Vth1 lower than a target valve voltage Vth_pgm.

[0057] refer to Figure 7 The pumping circuit 180' according to the second embodiment of the present invention supplies the write driving circuit 190 with the drain voltage Vd transmitted to one bit line in response to the control sign...

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Abstract

Disclosed herein is a program method of a flash memory device. First, flash memory cells depending on the word / byte unit among flash memory cells of a memory cell array are selected. And then, the selected flash memory cells are sequentially programmed so as to have a predetermined threshold voltage which is less than a target threshold voltage. After this, the selected flash memory cells either are simultaneously programmed from the predetermined threshold voltage up to the target threshold voltage, or are divided into plural groups to be programmed sequentially. With this program algorithm, although the integration degree of the flash memory device is increased and power supply voltage level is lowered, a sufficient amount of current required to a program can be supplied without the increase of the size of an integrated circuit die.

Description

[0001] This application claims priority from Korean Patent Application No. 1999-29786 filed on July 22, 1999, the contents of which are incorporated herein by reference in their entirety. technical field [0002] The present invention relates to flash memory devices, and more particularly to a high density NOR type flash memory device operating at a very low power supply voltage, and a method of programming the flash memory device. Background technique [0003] To provide non-volatile information storage, various computer systems employ flash memory. Conventional flash memory typically includes a program circuit for programming information within the flash memory cells and an erase circuit for erasing the memory cells. However, the voltage levels required for such programming and erasing circuits are different from those used for computer system power supply voltages. [0004] Certain flash memories require multi-voltage power supplies to accommodate programming and erasing...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G11C16/02G11C16/12H10B69/00
CPCG11C16/12H10B69/00
Inventor 李枓燮
Owner SAMSUNG ELECTRONICS CO LTD