Stacked I/O Cell Layout for Flip Chip Area Reduction
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Solution Overview
Problem
Conventional IC device layouts face inefficiencies as the number of I/O signals increases, leading to wasteful use of layout area due to the need for larger pad rings and increased spacing between I/O cells, particularly in flip chip designs where extra width or spacing is required for unique bump patterns and package constraints.
Innovation Solution
The implementation of a stacked I/O structure with a guard ring and two rows of I/O cells, where high voltage I/O circuits are placed on opposite sides of each cell to reduce the distance between rows and minimize signal noise interference, allowing for three rows of I/O bumps and efficient use of layout area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of I/O signals increases, then the I/O structure can accommodate more signals, but the layout area increases
Solution Approach 1:
The patent transitions from a conventional single-row pad ring layout to a stacked I/O structure with multiple rows arranged vertically. By utilizing the vertical dimension (stacking rows above each other) rather than only horizontal expansion, the design accommodates increased I/O signal counts without proportionally increasing the overall layout area, thus resolving the contradiction between signal quantity and area usage.
Solution Approach 2:
The stacked I/O structure nests multiple rows of I/O cells within a compact vertical arrangement. The first and second rows are positioned adjacent to each other in a nested configuration, allowing efficient space utilization. This nesting approach enables more I/O signals to be packed into a smaller footprint area compared to conventional single-row designs.
2Quantity of substance
If a second pad ring is added around the die periphery, then more I/O signals can be accommodated, but the layout area increases
Solution Approach 1:
Instead of adding a second horizontal pad ring around the die periphery, the patent stacks I/O cell rows vertically in a compact arrangement. This vertical stacking utilizes the third dimension (height/depth in layout) to increase I/O capacity without requiring additional horizontal layout area, thereby avoiding the area penalty associated with dual pad ring designs.
Solution Approach 2:
The patent merges multiple I/O cell rows into a single integrated stacked structure rather than maintaining separate independent pad rings. The first and second rows are positioned adjacent to each other and interconnected, forming a unified I/O structure that achieves higher signal capacity within a compact footprint compared to separate dual-ring configurations.
3Adaptability or versatility
If extra width or spacing is provided for flip chip packages, then package constraints are satisfied, but the layout area increases
Solution Approach 1:
The stacked I/O structure arranges I/O cell rows vertically with controlled spacing, utilizing the vertical dimension to provide necessary separation for flip chip bump patterns. This vertical arrangement satisfies flip chip package constraints regarding bump spacing and alignment while maintaining a compact horizontal footprint, avoiding the area waste of conventional designs that add excessive horizontal width or spacing.
Data Source
AI summary
An integrated circuit, such as a flip chip, may be configured to increase the I/O cells by stacking the I/O cells in two or more rows with external high voltage circuits on opposite sides of a respective cell to reduce the distance between the rows. In addition, the integrated circuit may include a guard ring around the I/O cells to reduce signal noise interference generated by the external high voltage circuits in the I/O cells.