| 摘要 |
A phase change RAM device is provided to improve electrical characteristics thereof by increasing gradually sizes of PN diodes from an adjacent region of a sense amplifier to a remote region of the sense amplifier. An N type impurity region is formed within an active region(110) of a silicon substrate(100). A plurality of PN diodes(131,132,133) are formed on the N type impurity region of the active region. A plurality of phase change cells include a thin film for heater, a line type phase change layer, and an upper electrode. The thin film for heater comes in contact with the PN diodes. A plurality of bit lines(171,172) are formed in the same direction as the direction of the phase change cell. A word line is arranged along the direction of the active region. A plurality of sense amplifiers(121,122) are connected to the bit lines. |
