Field of the Invention
The invention relates to a resistive memory, and more particularly, relates to an operating method for a resistive memory cell and a resistive memory using the operating method.
Description of Related Art
Resistive memory (Resistive random-access memory; RRAM) is a new type of non-volatile memory which utilizes changes in resistance state to memorize or store values. Owing to high compatibility with the logic process as well as advantages of fast writing speed and lower writing voltage, the resistive memory can satisfy requirements of low power consumption for various portable electronic products.
A basic structure of a resistive memory cell commonly used in the resistive memory is constituted by one transistor and one resistive memory (1T1R) or one diode plus one resistive memory (1D1R). In the resistive memory, three operations (forming, set and reset) are the three important steps for ensuring an electrical property and a data retention capability of the resistive memory cell. Optimized adjustment for the forming, set and reset operations is an important factor for improving a yield rate of the resistive memory. Particularly, for a conductive filament (CF) generated by performing the forming operation, said operation for generating the conductive filament has great influence to the operations of the resistive memory.
In general, after the in-depth forming operation is performed, most of the resistive memory cells should successfully be in a data logic 1 state (i.e., a high current state/a set state). However, a few number of the resistive memory cells with defect may be in a data logic 0 state (i.e., a low current state/a reset state) after the forming operation is performed. As a capacity of a device using the resistive memory grows larger, an amount of said resistive memory cells with defect will increase. Later, after a high temperature baking operation is performed multiple times on the resistive memory cells, it is possible that the resistive memory cells with defect cannot be used at all since the data retention capability may further deteriorate. Therefore, a repairing operation performed specifically for the resistive memory cells with defect is the key issue for improving the yield rate of the resistive memory.