SRAM Driver Transistor Segmentation Across Active Regions
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Solution Overview
Problem
The miniaturization of semiconductor devices leads to fluctuations in device characteristics and difficulties in simulating memory characteristics due to complex patterns and variations in active region and gate electrode shapes, making it challenging to optimize SRAM memory cell layouts effectively.
Innovation Solution
The semiconductor device incorporates a layout where driver transistors are divided into two transistors each, located over different active regions, allowing for improved patterning accuracy and reduced product quality instability, with active regions extending in the Y direction to simplify the layout and enhance simulation models.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If driver transistors are disposed over a single active region in a conventional SRAM layout, then the layout complexity is reduced, but device characteristics fluctuate due to miniaturization effects and the ability to improve soft-error immunity is limited
Solution Approach 1:
The driver transistor is divided into two separate transistors disposed over different active regions (first and second P wells). This segmentation allows each transistor to be independently optimized and positioned to improve soft-error immunity while maintaining manageable layout complexity through systematic arrangement.
Solution Approach 2:
The invention transitions from a single-plane layout to a multi-dimensional arrangement by utilizing different well regions (first P well and second P well) separated by an N well. This spatial distribution across multiple dimensions enhances soft-error immunity without proportionally increasing overall layout complexity.
2Area of moving object
If the SRAM memory cell pattern is miniaturized to increase density, then the device size is reduced, but fluctuations in device characteristics occur due to variations in active region and gate electrode shapes
Solution Approach 1:
By dividing the driver transistor into two separate transistors over different active regions, the invention reduces the channel length and area requirements for each individual transistor. This segmentation allows for better control of device characteristics in miniaturized structures while maintaining overall driver functionality.
Solution Approach 2:
Each active region (first P well and second P well) is independently optimized for specific functions. The driver transistors in different wells can have tailored dimensions and characteristics suited to their local requirements, improving overall device characteristic consistency despite miniaturization.
3Reliability
If complex patterns are used in SRAM memory cells to achieve higher functionality, then device performance is improved, but simulation difficulty increases due to complicated active region and gate electrode shapes
Solution Approach 1:
The driver transistor is segmented into two independent transistors with separate active regions and gate electrodes. This segmentation simplifies the simulation model by breaking down a complex multi-region structure into manageable independent units, reducing simulation complexity while maintaining functional performance.
Solution Approach 2:
The two driver transistors perform identical functions and can be modeled using the same simulation parameters and characteristics. This universality simplifies the simulation process by allowing repetitive use of standardized models rather than requiring unique complex models for each region.
4Manufacturing precision
If driver transistors are divided over different active regions, then product quality stability is improved and patterning accuracy is enhanced, but the number of transistors and layout elements increases
Solution Approach 1:
Dividing the driver transistor into two separate transistors creates simpler, more regularly shaped active regions and gate electrodes that are easier to pattern accurately. Although the number of elements increases, each element's simplicity compensates for this by reducing patterning complexity and improving manufacturing precision.
Data Source
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AI summary
A semiconductor device having an SRAM which includes: a monolithic first active region in which a first transistor and a fifth transistor are disposed; a second active region separated from the first active region, in which a second transistor is disposed; a monolithic third active region in which a third transistor and a sixth transistor are disposed; and a fourth active region separated from the third active region, in which a fourth transistor is disposed. Each driver transistor is divided into a first transistor and a second transistor (or a third transistor and a fourth transistor) and these driver transistors are disposed over different active regions.