阅读说明：本技术 编程抑制程序方法、存储器装置及控制器 (Program inhibit program method, memory device and controller ) 是由 林道远 杨怡箴 张耀文 于 2018-08-09 设计创作，主要内容包括：一种可缓解存储单元干扰的编程抑制程序方法、存储器装置及控制器。编程抑制程序方法包括以下步骤。对一存储单元阵列(cell array)的一存储单元串行(cell string)执行一校验程序(verify operation)。对该存储单元串行施加一电源脉冲(power pulse)。对该存储单元串行执行该编程抑制程序。施加该电源脉冲的步骤在该编程抑制程序的步骤之前执行。(A program inhibit procedure method, a memory device and a controller capable of relieving memory cell interference are provided. The program inhibit procedure method includes the following steps. A verification procedure (verify operation) is performed on a cell string of a cell array (cell array). A power pulse is applied to the memory cells in series. The program inhibit procedure is performed serially on the memory cells. The step of applying the power pulse is performed before the step of the program inhibit procedure.)

1. A program inhibit operation (program inhibit operation) method, comprising:

Executing a verification procedure (verify operation) on a cell string of a cell array (cell array);

Serially applying a power pulse to the memory cell; and

executing the program inhibit program to the memory cells in series;

Wherein the step of applying the power pulse is performed before the step of programming the program inhibit procedure.

2. The method of claim 1, wherein in the step of applying the power pulse, the power pulse is 0.5-1V.

3. The method of claim 1, wherein in the step of applying the power pulse, the power pulse is applied for 5-15 microseconds (micro seconds).

4. The method of claim 1, wherein the power pulse is applied to all memory cells of the series of memory cells.

5. A memory device, comprising:

A memory cell array (cell array);

A word line decoder (word line decoder) connected to a plurality of word lines of the memory cell array;

A bit line decoder (bit line decoder) connected to the bit lines of the memory cell array; and

A controller connected to the word line decoder and the bit line decoder to perform a verify operation, a power pulse operation, and a program inhibit operation on a cell string of the memory cell array;

Wherein the controller applies the power pulse prior to the program inhibit procedure.

6. The memory device of claim 5, wherein the power pulse is 0.5-1V, and the power pulse is applied for 5-15 micro seconds (micro seconds).

7. The memory device of claim 5, wherein the power pulse is applied to all memory cells of the series of memory cells.

8. A controller is connected with a word line decoder (word line decoder) and a bit line decoder (bit line decoder), the word line decoder is connected with a plurality of word lines of a memory cell array, the bit line decoder is connected with a plurality of bit lines of the memory cell array, and the controller is used for controlling the word line decoder and the bit line decoder to be connected with the bit lines of the memory cell array

Executing a verification procedure (verify operation) on a cell string (cell string) of the memory cell array;

Serially applying a power pulse to the memory cell; and

executing a program inhibit operation (program inhibit operation) to the memory cell in series;

Wherein the controller applies the power pulse prior to the program inhibit procedure.

9. the controller of claim 8, wherein the power pulse is 0.5-1V, and the power pulse is applied for 5-15 micro seconds (micro seconds).

10. The controller of claim 8, wherein the power pulse is applied to all memory cells of the series of memory cells.

Technical Field

the present invention relates to an operating method, a memory device and a controller, and more particularly, to a program inhibit program method, a memory device and a controller capable of alleviating memory cell disturb.

Background

with the development of memory technology, various memories are continuously being developed. The memory cells of the memory can be programmed or erased to record "0" or "1" data. For example, Fowler-Nordheim tunneling (FN-tunneling) is used for programming NAND type memories. While some memory cells are programmed by hot electron, other memory cells are prevented from being programmed against the FN-tunneling by a program inhibit operation (program inhibit operation). For example, increasing the channel potential (channel potential) is used to reduce the voltage difference between the programming voltage (VprogramWL) of the word line and the channel (channel). However, some programming patterns (programming patterns) may cause an environment in which hot-electrons (hot-electrons) are easily generated when other memory cells are performing a program inhibit procedure (program inhibit operation), and thus hot-electron mode interference (hot-electron interference) is generated when the program inhibit procedure (program inhibit operation) is performed.

Disclosure of Invention

The invention relates to a program inhibition program method, a memory device and a controller capable of relieving memory cell interference, wherein a power supply pulse is applied before a program inhibition program, so that a potential drop phenomenon (down-couplingphenomenon) can be eliminated. Since the potential drop phenomenon is eliminated, the channel potential curve can be maintained stable during the program inhibit procedure without inducing any hot electron interference in the memory cell.

according to a first aspect of the present invention, a program inhibit operation (program inhibit operation) method is provided. The program inhibit procedure method includes the following steps. A verification procedure (verify operation) is performed on a cell string of a cell array (cell array). A power pulse is applied to the memory cells in series. The program inhibit procedure is performed serially on the memory cells. The step of applying the power pulse is performed before the step of the program inhibit process.

According to a second aspect of the present invention, a memory device is provided. The memory device includes a memory cell array (cell array), a word line decoder (word line decoder), a bit line decoder (bit line decoder), and a controller. The word line decoder is connected to a plurality of word lines of the memory cell array. The bit line decoder is connected to a plurality of bit lines of the memory cell array. The controller is connected to the word line decoder and the bit line decoder to perform a verify procedure (verify operation), apply a power pulse (power pulse), and perform the program inhibit procedure (program inhibit operation) on a cell string of the memory cell array. The controller applies the power pulse prior to the program inhibit procedure.

According to a third aspect of the invention, a controller is presented. The controller is connected to a word line decoder and a bit line decoder. The word line decoder is connected to a plurality of word lines of a memory cell array. The bit line decoder is connected to a plurality of bit lines of the memory cell array, and the controller is configured to execute a verification procedure (verify operation) on a cell string of the memory cell array, apply a power pulse (power pulse) to the cell string, and execute a program inhibit procedure (program inhibit operation) on the cell string. The controller applies the power pulse prior to the program inhibit procedure.

In order that the manner in which the above recited and other aspects of the present invention are obtained can be understood in detail, a more particular description of the invention, briefly summarized below, may be had by reference to the appended drawings, in which:

Drawings

FIG. 1 depicts a memory device.

fig. 2 shows a cell string of the memory cell array.

FIG. 3 is a flow chart of a program inhibit procedure method.

FIG. 4 shows variations in word line voltage, conduction voltage, supply voltage, serial select line voltage, and bit line voltage.

FIGS. 5A-5D illustrate channel potential (channel potential) curves for a series of memory cells.

FIG. 6 depicts a trapped charge map (E-trapped charge pattern) of a memory cell.

FIG. 7 is a flow chart of a program inhibit procedure method for mitigating memory cell disturb.

FIG. 8 shows variations in word line voltage, conduction voltage, supply voltage, serial select line voltage, and bit line voltage.

FIG. 9 shows two channel potential curves for two time points in series of memory cells.

FIG. 10 shows a comparison of two channel potential curves for two memory cell strings at two time points.

FIG. 11 shows a comparison of two trapped charge maps.

[ notation ] to show

100: memory device

110: memory cell array

111: memory cell series

120: word line decoder

130: bit line decoder

140: controller

BL: bit line

CE. CE': trapped charge map

CL0, CLn-1, CLn +1, CL 31: memory cell

CT1, CT1 ', CT1 ' A, CT2, CT3, CT3 ', CT4, CT5, CT 6: channel potential curve

DC: phenomenon of potential drop

WL, WLn-2, WLn-1, WLn +1, WLn +2, WL 31: word line

PD: channel potential difference

PW, PW': supply voltage

PP: pulse of power supply

S110, S110 ', S120', S130 ', S140': step (ii) of

T0, T0 ', T1, T1', T1 'A, T2, T2', T3, T3 ', T4, T4', T5, T5 ', T6, T6': point in time

VBL, VBL': bit line voltage

Vpass, Vpass': on-state voltage

VSSL, VSSL': serial select line voltage

VWLn, VWLn': word line voltage

Detailed Description

Referring to FIG. 1, a memory device 100 is shown. The memory device 100 includes a memory cell array (cell array)110, a word line decoder (word line decoder)120, a bit line decoder (bit line decoder)130, and a controller 140. The memory cell array 110 is, for example, a three-dimensional NAND (3D) memory, a floating gate memory, a nitride-based charge storage memory, a gate-all-around memory, or a vertical channel memory. The word line decoder 120 is connected to a plurality of word lines WL of the memory cell array 110. The bit line decoder 130 is connected to a plurality of bit lines BL of the memory cell array 110.

Referring to fig. 2, a cell string 111 of the memory cell array 110 is shown. The memory cell string 111 is connected to word lines WLn 2, WLn 1, WLn + i, WLn + 2. When a program voltage is applied to the word line WLn, the memory cells in the memory cell string 111 that are not required to be programmed need to be subjected to a program inhibit procedure (program inhibit).

Please refer to fig. 3-5D. FIG. 3 is a flow chart of a program inhibit procedure method. Fig. 4 shows variations of the word line voltage VWLn, the pass voltage Vpass, the power supply voltage PW, the serial selection line voltage VSSL, and the bit line voltage VBL. Fig. 5A to 5D show channel potential (channel potential) curves CT1 to CT6 of the memory cell string 111. In step S110, the controller 140 executes a verification procedure (verify operation) on the cell string 111 from time T0 to time T1. In the verify process, the word line voltage VWLn is increased to 7V, the pass voltage Vpass is increased to 7V, the power supply voltage PW is maintained at 0V, the serial select line voltage VSSL is increased to 7V, and the bit line voltage VBL is increased to 0.6V. Referring to fig. 5A, a channel potential curve CT1 of the memory cell string 111 at a time point T1 is shown. When the verify process is completed, the memory cell CLn connected to the word line WLn is turned off, and a down-coupling phenomenon DC is generated, and the channel potential thereof is lowered to-4V. Between the memory cell CLn and the memory cell CLn +1 (connected to the word line WLn +1), a channel potential difference (channel potential) PD is formed.

Next, in step S130, the controller 140 executes a pre-program operation (pre-program operation) on the memory cell string 111. In the pre-programming process, the word line voltage VWLn is maintained at 0V, the pass voltage Vpass is maintained at 0V, the power supply voltage PW is maintained at 0V, the serial select line voltage VSSL is increased to 4V, and the bit line voltage VBL is increased to 4V. Referring to fig. 5B, a channel potential curve CT2 of the memory cell string 111 at a time point T2 is shown. During charging of the serial select line voltage VSSL and the bit line voltage VBL, the memory cells CLn +1 CL31 (connected to the word lines WLn +1 WL31) are pre-programmed. On the other hand, the memory cells CL0 CLn-1 remain unchanged because the memory cell CLn-1 (connected to word line WLn-1) is isolated from the memory cell string 111.

In step S140, the controller 140 executes a program inhibit operation (program inhibit operation) on the memory cell string 111. At the beginning of the program inhibit procedure (i.e., time point T3), the word line voltage VWLn is increased to 8V, the pass voltage Vpass is increased to 8V, the power voltage PW is maintained at 0V, the serial select line voltage VSSL is maintained at 0V, and the bit line voltage VBL is maintained at 0V. Referring to fig. 5C, a channel potential curve CT3 of the memory cell string 111 at a time point T3 is shown. When the pass voltage Vpass is applied to all the memory cells, electrons are injected into the first half of the memory cells and the channel potential is raised. At this time, the pass voltage Vpass raises the channel potential of the memory cell CLn.

In the program inhibit procedure (from time T3 to time T6), the word line voltage VWLn is increased from 8V to 24V, the pass voltage Vpass is maintained at 8V, the power voltage PW is maintained at 0V, the serial select line voltage VSSL is maintained at 0V, and the bit line voltage VBL is maintained at 0V. Referring to FIG. 5D, the channel potential curves CT3 and CT6 of the memory cell string 111 at time T3 and T6 are shown. As the word line voltage VWLn increases, the channel potential difference (potential) PD decreases. When the electron barrier is eliminated, a transient current flows from the memory cell CLn to the memory cell CLn + 1. This causes hot electron interference to the memory cell CLn + 1.

Referring to fig. 6, a trapped charge pattern (E-trapped charge pattern) CE of the memory cell CLn +1 (injected with transient current) is shown. In this figure, the detection of the hot electron signal is performed for memory cell CLn + 1. The trapped charge accumulated by the nitrogen compounds increases over time as shown by the trapped charge map CE. Therefore, the memory cell CLn +1 is indeed disturbed during the program inhibit procedure.

Please refer to fig. 7-9. FIG. 7 is a flow chart of a program inhibit procedure method for mitigating memory cell disturb. Fig. 8 shows word line voltage VWLn ', pass voltage Vpass, power voltage PW', serial select line voltage VSSL ', and bit line voltage VBL', and fig. 9 shows channel potential curves CT1 'and CT 1' a of the memory cell string 111 at time T1 'and T1' a.

In step S110 ', the controller 140 executes a verification procedure (verify operation) on the cell string 111 from time T0 ' to time T1 '. In the verify process, the word line voltage VWLn 'is increased to 7V, the pass voltage Vpass is increased to 7V, the power supply voltage PW' is maintained at 0V, the serial select line voltage VSSL 'is increased to 7V, and the bit line voltage VBL' is increased to 0.6V. Please refer to the channel potential curve CT1 'of the memory cell string 111 at the time point T1' shown in fig. 9. When the verify process is just completed, the memory cell CLn is turned off, and the channel potential thereof is lowered to-4V due to a potential-falling phenomenon (down-coupling phenomenon) DC. Between the memory cell CLn and the memory cell CLn +1, a channel potential difference (channel difference) PD is formed.

Next, in step S120', the controller 140 applies a power pulse (power pulse) PP (shown in fig. 8) to the memory cell string 111. In this step, the word line voltage VWLn 'is maintained at 0V, the pass voltage Vpass' is maintained at 0V, the power supply voltage PW 'is increased to 0.5V to 1V, and the serial select line voltage VSSL' is maintained at 0V. In one embodiment, the power pulse PP is applied for 5-15 micro seconds (micro seconds) and is applied to all the memory cells of the memory cell series 111. Please refer to the channel potential curve CT1 'a of the memory cell string 111 at the time point T1' a shown in fig. 9. After the power supply pulse PP is applied, the potential-falling phenomenon (down-coupling phenomenon) DC can be eliminated, and the channel potential difference PD between the memory cell CLn and the memory cell CLn +1 can also be eliminated.

Next, in step S130', the controller 140 executes a pre-program operation (pre-program operation) on the memory cell string 111. In the pre-programming procedure, the word line voltage VWLn ' is maintained at 0V, the pass voltage Vpass ' is maintained at 0V, the power supply voltage PW ' is maintained at 0V, the serial select line voltage VSSL ' is increased to 4V, and the bit line voltage VBL ' is increased to 4V.

In step S140', the controller 140 executes a program inhibit operation (program inhibit operation) on the memory cell string 111. At the beginning of the program inhibit procedure (i.e., time point T3), the word line voltage VWLn is increased to 8V, the pass voltage Vpass 'is increased to 8V, the power supply voltage PW' is maintained at 0V, the serial select line voltage VSSL 'is maintained at 0V, and the bit line voltage VBL' is maintained at 0V.

Referring to fig. 10, a comparison between the channel potential curve CT3 'of the memory cell string 111 at the time point T3' and the channel potential curve CT3 of the memory cell string 111 at the time point T3 is shown. As shown in fig. 10, the large channel potential difference PD originally existing between the memory cell CLn and the memory cell CLn +1 has disappeared at a time point T3'.

In the program inhibit procedure (from time T3 ' to time T6 '), the word line voltage VWLn ' is increased from 8V to 24V, the pass voltage Vpass ' is maintained at 8V, the power supply voltage PW ' is maintained at 0V, the serial select line voltage VSSL ' is maintained at 0V, and the bit line voltage VBL ' is maintained at 0V. Since the potential drop phenomenon has been eliminated, the channel potential curve CT3 ' can be maintained stable from time T3 ' to time T6 ' during the program inhibit procedure without inducing any hot electron interference in the memory cell CLn + 1.

Referring to fig. 11, a comparison of the trapped charge map CE (fig. 6) and the trapped charge map CE' (without transient current injection) is shown. The trapped charge accumulated by the nitrogen compound is maintained at a low level all the time as shown in the trapped charge map CE'. Therefore, the memory cell CLn +1 is not disturbed during the program inhibit process.

According to the above embodiments, the applied power pulse PP can eliminate hot electron interference generated when the word line WLn is activated. In this embodiment, the application of the power pulse PP is performed between the verification process and the program inhibit process to eliminate the potential-falling phenomenon (down-coupling phenomenon) DC and mitigate the risk of hot electron interference.

The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.