| 摘要 |
An improved layout pattern for electrostatic discharge protection is disclosed. A first heavily doped region of a first type is formed in a well of said first type. A second heavily doped region of a second type is formed in a well of said second type. A battlement layout pattern of said first heavily doped region is formed along the boundary of said first heavily doped region and said second heavily doped region. A battlement layout pattern of said second heavily doped region is formed along the boundary of said first heavily doped region and said second heavily doped region. By adjusting a distance between the battlement layout pattern of a heavily doped region and a edge of well of said second type, i.e. n-well, a first distance will be shorter than what is typically required by the layout rules of internal circuit; and a second distance will be longer than the first distance to ensure that the I/O device have a better ESD protection capability. Accordingly, by properly adjusting the breakdown voltage of ESD device within I/O circuit, i.e. adjusting the distance between the edge of n-well and the battlement layout pattern of heavily doped regions, it will help to reduce the chip area and improve the ESD reliability.
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