Stacked Pick-Up Region Cell Layout With Integrated Well Taps
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Solution Overview
Problem
In integrated circuits, the increasing density of transistors leads to issues with latchup, causing undesirable short circuits, and existing layouts with tap cells occupy valuable area and increase metal connections, resulting in RC delays.
Innovation Solution
The implementation of pick-up regions within cells of varying heights, where n-type and p-type pick-up regions are used to conductively connect wells to supply voltages VDD and VSS, respectively, preventing latchup by maintaining voltage levels and reducing leakage currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tap cells are used to couple n-type wells to VDD and p-type wells to VSS, then latchup prevention is achieved, but valuable layout area is occupied and metal connections increase causing RC delays
Solution Approach 1:
The patent combines the functions of standard cells and tap cells by integrating pick-up regions directly into the standard cell structure. The n-type pick-up region is formed within the n-type well of the standard cell, and the p-type pick-up region is formed within the p-type well, allowing the standard cell to simultaneously perform logic functions and provide power rail connections without requiring separate tap cells.
Solution Approach 2:
The standard cell is designed to serve multiple functions: it performs the intended logic operation while also providing latchup prevention through integrated pick-up regions. The pick-up regions enable the standard cell to act as both a functional logic element and a power distribution element, eliminating the need for dedicated tap cells.
2Reliability
If tap cells are used to couple n-type wells to VDD and p-type wells to VSS, then latchup prevention is achieved, but metal connections increase causing RC delays
Solution Approach 1:
The patent combines the functions of standard cells and tap cells by integrating pick-up regions directly into the standard cell structure. The n-type pick-up region is formed within the n-type well of the standard cell, and the p-type pick-up region is formed within the p-type well, allowing the standard cell to simultaneously perform logic functions and provide power rail connections without requiring separate tap cells.
3Shape
If standard cells of uniform height are used, then layout regularity is maintained, but cells with varying functional requirements cannot be efficiently accommodated
Solution Approach 1:
The patent introduces variable cell heights as an additional degree of freedom in the layout design. By allowing standard cells to have different heights while maintaining the same width and alignment characteristics, the design can accommodate different functional requirements without sacrificing layout regularity. The pick-up regions are positioned at different vertical positions within cells of varying heights to optimize power rail connections.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution effectively prevents latchup and reduces wasted area and metal connections, thereby improving layout efficiency and reducing RC delays in integrated circuits.
Implementation Method 1
n-type and p-type pick-up regions are used to conductively connect wells to supply voltages VDD and VSS, respectively
Data Source
AI summary
A method of forming a semiconductor device. The method includes forming a first well of a first-type in a substrate of a second-type, forming a first active zone of the first-type in a second well of the second-type on the substrate, and forming a second active zone of the second-type in the first-type well. The method also includes forming a first pick-up region of the first-type located in the first well, and forming a second pick-up region of the second-type located in the second well. Each of the first active zone and the second active zone extends in a first direction. The first pick-up region and the second pick-up region are separated from each other, by the first active zone and the second active zone, along a direction that is different from the first direction.