KR20000012867A - Cell data sensing circuit of semiconductor memory device - Google Patents

Abstract

PURPOSE: A cell data sensing circuit of semiconductor memory device is provided to stably make operation of circuit and improve confidence of a semiconductor memory device. CONSTITUTION: The circuit comprises a memory cell data detector for detect a sensing signal according to a data stored in a memory cell, a reference signal generator for generating two reference signal stored in two or more reference cells connected in serial, and a comparator for receiving the sensing signal from the memory cell data detector and the reference signal from the reference signal generator and comparing the sensing signal with the reference signal. The data stored in the memory cell is detected by the signal outputted from the comparator.

Description

Cell Data Sensing Circuit of Semiconductor Memory Device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor memory device, and more particularly, to a cell data sensing circuit of a semiconductor memory device having a reference voltage generation circuit to be compared with it for sensing a data state written in a memory cell.

In general, a semiconductor memory device, for example a flash memory, is executed by a program for data writing by an internal algorithm, where programming is performed for a predetermined time irrespective of a change in a threshold voltage of a cell.

After data writing, the flash memory performs a verification process for verifying this. The reference voltage level set in the reference cell is compared with the threshold voltage of the memory cell currently written. That is, it is determined whether the programmed threshold voltage of the memory cell has reached the threshold voltage level of the reference cell, and the writing process of the cell is determined to be pass or fail.

1 is a circuit diagram illustrating a split gate type flash memory device according to the related art. For reference, a split gate type flash memory device has a shape in which a selection transistor for selecting a memory cell surrounds one side of floating and control gates (a, b) sequentially stacked on top of a control gate (b) of the memory cell. It has a split gate electrode structure that is deformed into the selection gate (c) and connected to the gate electrode of the memory cell.

The circuit detects and outputs a first load Rm connected to a power supply voltage terminal and a corresponding sensing voltage Vm according to data recorded in a memory cell 12 connected to the load Rm. ), A reference voltage generator 20 for generating a second load Rref connected to a power supply voltage terminal and a reference voltage Vref set in the reference cell 22 connected to the load Rref, and the memory. The cell data detector 10 and the reference voltage generator 20 receive sensing voltages and reference voltages Vm and Vref, respectively, and compare the two inputs and output the difference.

In the cell data sensing circuit of the semiconductor memory device configured as described above, the memory cell 12 of the memory cell data detector 10 and the reference cell 22 of the reference voltage generator 20 are set to a constant threshold voltage. That is, the threshold voltage of the reference cell 22 is set to be in a specific voltage state by adjusting ultraviolet or external threshold voltage, and the threshold voltage of the memory cell 12 is mutually dependent on whether the cell is programmed or erased. Will have a different threshold voltage.

Therefore, when sensing data of a selected memory cell among a plurality of memory cell arrays, a constant current always flows to the reference cell 22 of the reference voltage generator 20 under a specific bias condition, and the memory cell of the memory cell data detector 10 In Fig. 12, there is little current or several tens of mA depending on whether the cell's current state is programmed or erased. Accordingly, the comparator 30 receives the sensing voltage Vm of the memory cell 12 of the comparison target applied from the memory cell data detector 10 to the inverting terminal (-) and generates a reference voltage at the non-inverting terminal (+). The reference voltage Vref of the reference cell 22 applied from the unit 20 is input to compare the two voltages Vm and Vref. The output signal Vout according to whether the sensing voltage Vm of the memory cell is high or low with respect to the reference voltage Vref determines whether the memory cell 12 is programmed or erased.

However, since the memory cells 12 and the reference cells 22 are distributed without having the same characteristics due to process conditions, temperature, etc., the threshold voltages set in the memory cells 12 and the reference cells 22 are changed for each address. In particular, when the amount of current flowing through the memory cell 12 changes due to a process change, the cell data sensing circuit of the semiconductor memory device causes an error.

SUMMARY OF THE INVENTION An object of the present invention is to serialize a reference voltage generating circuit so that the threshold voltage of a reference cell can be adjusted according to a change in the threshold voltage of a corresponding cell when data of a memory cell changed by a manufacturing process is solved to solve the problems of the prior art. The present invention provides a cell data sensing circuit of a semiconductor memory device capable of improving stable circuit operation and device reliability by having a plurality of reference cells connected to each other.

1 is a circuit diagram illustrating a cell data sensing circuit of a split gate type flash memory device according to the prior art;

2 is a circuit diagram illustrating a cell data sensing circuit of the split gate type flash memory device according to the present invention.

* Description of the symbols for the main parts of the drawings *

100: memory cell data detector 102: memory cell

110: reference voltage generator 112: first reference cell

114: second reference cell 120: comparison unit

In order to achieve the above object, the present invention provides a memory cell data detection unit for detecting a detection signal according to the recorded data of the memory cell, a reference signal generator for generating a reference signal set to two or more reference cells connected in series; The apparatus may include a comparison unit configured to receive a reference signal from a memory cell data detection unit and the reference signal generator and compare the two signals, and detect data of the memory cell by a signal output through the comparison unit.

According to the present invention, when the threshold voltage of the memory cell is changed by the manufacturing process, the threshold voltage of the second reference cell is set so that the threshold voltage set in the first reference cell of the reference signal generator can be adjusted to the change amount of the memory cell. do.

Therefore, the present invention can implement a stable circuit operation when sensing the data of the memory cell by the reference signal generator that is increased by two or more than when one reference cell for setting the reference voltage.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a circuit diagram illustrating a cell data sensing circuit of a split gate type flash memory device according to the present invention.

The split gate type flue memory device according to the present invention has a sensing voltage Vm which is a threshold voltage according to data written in a first load Rm connected to a power supply voltage terminal and a memory cell 12 connected to the load Rm. ) Is set in the memory cell data detection unit 100 that detects and outputs the second cell, the second load Rref connected to the power supply voltage terminal, and the first and second reference cells 112 and 114 connected in series to the load Rref. The sensing voltage and the reference voltages Vm and Vref are received from the reference voltage generator 110 generating the reference voltage Vref, the memory cell data detector 100 and the reference voltage generator 110, respectively. Comparing unit 120 for comparing the two inputs and outputs the difference.

In the cell data sensing circuit of the semiconductor memory device according to the present invention configured as described above, first, the memory cell 102 of the memory cell data detector 100 and the first reference cell 112 of the reference voltage generator 110 are constant. When the voltage is set to the voltage, the comparison unit 120 determines whether the set voltage is the same.

At this time, the comparator 120 receives the sensing voltage Vm of the memory cell 102 of the comparison target applied from the memory cell data detector 100 to the inverting terminal (-) and receives a reference voltage to the non-inverting terminal (+). When the reference voltage Vref set to the first reference cell 112 applied from the generator 110 is input and the two voltages Vm and Vref are compared and the two voltages are not the same, the memory cell 102 during the manufacturing process It is determined that the threshold voltage set at) is changed to a predetermined voltage.

As the threshold voltage of the memory cell 102 changes, the reference voltage of the reference voltage generator 110 should also vary. Accordingly, the reference voltage generator 110 sets a reference threshold voltage in the second reference cell 114 by the changed voltage difference. When the second reference cell 114 is programmed, the entire reference voltage of the reference voltage generator 110 may be set. (Vref) is low, and erasing it increases the overall reference voltage (Vref).

Thereafter, during the data sensing operation, the comparator 120 receives the sensing voltage Vm of the memory cell 102 of the comparison target applied from the memory cell data detector 100 to the inverting terminal (−) and receives the non-inverting terminal (+). ) And receive the reference voltages Vref of the first and second reference cells 112 and 114 applied from the reference voltage generator 110 and compare the two voltages Vm and Vref. The output signal Vout according to whether the sensing voltage Vm of the memory cell is high or low with respect to the reference voltage Vref determines whether the memory cell 102 is programmed or erased.

As described above, since the reference cells for setting the reference voltages of the reference signal generator are increased to two or more, the reference threshold voltages of the reference cells may also be adjusted according to the amount of change in the threshold voltage of the memory cells.

Therefore, the present invention has the effect of improving semiconductor memory stable circuit operation and device reliability.

Claims (1)

A memory cell data detector for detecting a detection signal according to the recorded data of the memory cell; A reference signal generator for generating a reference signal set in at least two reference cells connected in series; And And a comparison unit configured to receive the reference signals of the memory cell data detection unit and the reference signal generator and compare the two signals, and detect data of the memory cell by a signal output through the comparison unit. Cell data sensing circuit.