Macronix International Co., Ltd.

Shi-Charng Ai

Chin-Yi Huang

Mam-Tsung Wang

Chin-Hsi Lin

Ful-Long Ni

Chien-Sing Lee

The present invention provides a method and an apparatus for programming a selected call within a virtual ground EPROM array cell without disturbing adjacent array cells. The electrical disturbance of data stored in adjacent cells is limited in a number of ways: (1) a column connection circuit is provided for selectively coupling together adjacent pairs of even-odd or odd-even column lines so that source and drain terminals of adjacent memory cells are electrically coupled together, thereby preventing the data stored within the adjacent cells from being disturbed; (2) a current limiter circuit is provided for lowering a potential on a terminal of the selected cell at a controlled rate during programming so that voltages on terminals of the selected cell do not disturb data stored on adjacent memory cells; (3) the order in which programming signals are applied to terminals of the selected cell are controlled in such a way as to reduce the disturbance of data on adjacent cells; and (4) high wordline and data line voltages are applied to the selected cell in two steps, first to an intermediate voltage, and then to a high voltage. This reduces the disturbance to adjacent cells and improves programming.

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Taipei, Taiwan

Shi-Charng Ai