Standard Cell Spacer Bars for Drive Current Consistency
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Solution Overview
Problem
The variation in spacing between active regions in standard cells of semiconductor devices leads to unpredictable stress application and drive current variations in MOS devices, affecting their performance.
Innovation Solution
The introduction of spacer bars of specific conductivity types adjacent to and disconnected from active regions in semiconductor substrates, which regulate the spacing between active regions and neighboring regions, thereby controlling the stress applied by STI regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If standard cells are placed relatively randomly on a semiconductor chip, then design flexibility and packing density are improved, but spacing variation between active regions causes significant drive current variation
Solution Approach 1:
The patent introduces dummy active regions with specific conductivity types adjacent to STI regions to locally compensate for stress effects. This creates non-uniform doping patterns that specifically target the stress-induced carrier concentration variations near STI regions, thereby normalizing drive current without constraining overall cell placement flexibility.
Solution Approach 2:
The patent modifies the electrical parameters (carrier concentration) of the semiconductor substrate by introducing dummy active regions with controlled doping types. This changes the local electrical characteristics to compensate for stress effects, allowing random cell placement while maintaining current consistency through parameter adjustment rather than geometric constraint.
2Object-affected harmful factors
If spacing between active regions is increased, then stress from STI regions is reduced, but drive current becomes highly variable and unacceptable for certain designs
Solution Approach 1:
The patent converts the harmful stress effect of STI regions into a beneficial compensation mechanism by introducing dummy active regions with opposite conductivity types. These dummy regions generate stress-induced carrier concentration changes that counterbalance the harmful STI effects, transforming the problem into a solution through controlled parameter manipulation.
Solution Approach 2:
The patent applies preliminary counter-actions by placing dummy active regions with specific conductivity types adjacent to STI regions before the actual MOS devices operate. This pre-compensation establishes a baseline carrier concentration that offsets the impending stress effects, ensuring predictable drive current from the outset.
3Reliability
If spacer bars are introduced to regulate spacing, then stress consistency is improved, but device structure becomes more complex
Solution Approach 1:
The patent merges the functions of active regions and spacing regulation into a single integrated structure. The dummy active regions serve dual purposes: they regulate the effective spacing between functional active regions and simultaneously provide stress compensation through their doping characteristics, eliminating the need for separate spacer structures.
Solution Approach 2:
The dummy active regions perform multiple functions: they act as spacing regulators, stress compensation elements, and electrical isolation structures. This multi-functionality reduces overall device complexity by consolidating multiple structural elements into a single versatile component that addresses several problems simultaneously.
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 approach ensures predictable performance of MOS devices by maintaining consistent stress levels across MOS devices, reducing variations in drive current and improving overall circuit speed.
Implementation Method 1
STI region 14 typically applies a compressive stress to active region 6, and hence adversely affects the drive current of PMOS device 2. Further, the magnitude of the stress applied by STI region 14 is affected by the value of spacing S1
Data Source
AI summary
An integrated circuit structure includes a semiconductor substrate; a first active region in the semiconductor substrate; and a second active region in the semiconductor substrate and of an opposite conductivity type than the first active region. A gate electrode strip is over the first and the second active regions and forms a first MOS device and a second MOS device with the first active region and the second active region, respectively. A first spacer bar is in the semiconductor substrate and connected to the first active region. At least a portion of the first spacer bar is adjacent to and spaced apart from a portion of the first active region. A second spacer bar is in the semiconductor substrate and connected to the second active region. At least a portion of the second spacer bar is adjacent to and spaced apart from a portion of the second active region.