IO Cell Rows for Latchup Prevention in Semiconductor ICs
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Solution Overview
Problem
The increasing scale of semiconductor integrated circuits leads to a problem of area expansion due to the need for larger inter-transistor and inter-well distances to prevent latchup errors, which are caused by the significant difference in power supply voltage between high and low power supply regions.
Innovation Solution
The configuration of semiconductor integrated circuit devices with multiple rows of IO cells, where high power supply voltage regions of adjacent rows are opposed, and low power supply voltage regions are placed closer to the core region, eliminating the need for additional space to prevent latchup errors without increasing the device area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large inter-transistor and inter-well distances are secured between high and low power supply voltage regions to prevent latchup errors, then reliability is improved, but device area increases
Solution Approach 1:
The IO cells are divided into first and second rows with distinct voltage region arrangements. The first row has high voltage regions closer to the chip edge, while the second row has low voltage regions closer to the chip edge. This segmentation allows adjacent rows to have opposing voltage regions facing each other, creating natural isolation barriers that prevent latchup errors without requiring additional spacing.
Solution Approach 2:
Instead of the conventional arrangement where all IO cells have the same voltage region orientation, this patent inverts the arrangement in alternating rows. The first IO cell row has high voltage regions at the chip edge side, while the second IO cell row has low voltage regions at the chip edge side. This inverted pattern causes high voltage regions of one row to face low voltage regions of the adjacent row, providing inherent latchup protection.
2Device complexity
If IO cells are arranged in a single row around the core region, then device complexity is reduced, but the area determined by IO cells increases
Solution Approach 1:
The patent transitions from a single-row IO cell arrangement to a multi-row arrangement with alternating voltage region orientations. By adding the dimension of row alternation and utilizing the space between adjacent rows, the design achieves more efficient space utilization while maintaining relatively simple device structure.
3Reliability
If large space is secured between IO cells and core region to prevent latchup errors, then reliability is improved, but device area increases
Solution Approach 1:
The patent merges the latchup prevention function into the normal IO cell arrangement structure itself. By alternating the voltage region orientations in adjacent rows, the design creates inherent isolation between the core region and high voltage regions without requiring additional protective structures or increased spacing. The alternating pattern itself serves as the protection mechanism.
Data Source
AI summary
A semiconductor integrated circuit device including a plurality of rows of IO cells has a configuration capable of avoiding a latchup error without causing an increase in area. The device includes a first IO cell row placed closest to an edge of a chip and a second IO cell row placed adjacent to a core region side of the first IO cell row. Each of the IO cells of the first and second IO cell rows has a high power supply voltage region and a low power supply voltage region provided separately in a direction perpendicular to a direction in which the IO cells are lined up. The IO cell rows are placed so that the high power supply voltage regions of these rows are mutually opposed.