MOS Transistor Pairing for In-Vehicle Semiconductor Reliability
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Solution Overview
Problem
In semiconductor devices used in in-vehicle electronic control systems, current mirror and differential amplifier circuits experience characteristic variations over time due to thermal and mechanical stress, affecting the accuracy and reliability of the circuits.
Innovation Solution
The semiconductor device incorporates a pair of metal-oxide-semiconductor (MOS) transistors with insulation separation walls that maintain consistent relative characteristics by ensuring equal distances between the gate oxide films and the insulation separation walls, reducing the impact of stress on transistor performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If transistors are separated by 10 μm or more from the interface between active region and element separation region, then manufacturing precision of transistor characteristics is improved, but device area increases and characteristic variations with time are not sufficiently reduced
Solution Approach 1:
The patent introduces an intermediary structure (insulation separation wall with specific distance configuration) between the transistor gate oxide film and the element separation region interface. This intermediary arrangement mediates the stress transmission, reducing the direct impact of thermal and mechanical stress from the element separation region on the transistor characteristics, thereby maintaining characteristic consistency without requiring excessive separation distance.
Solution Approach 2:
The patent changes the critical parameter from the distance between transistor and element separation region interface to the distance between gate oxide film and insulation separation wall. By controlling this specific parameter (distance) to be equal for paired transistors, the invention achieves stress compensation and characteristic consistency while reducing the overall separation distance required, thus decreasing device area.
2Manufacturing precision
If transistors are separated by large distance from element separation region interface, then manufacturing precision is improved, but reliability under thermal and mechanical stress deteriorates due to characteristic variations with time
Solution Approach 1:
The patent changes the controlling parameter from the distance to the element separation region interface to the distance from the gate oxide film to the insulation separation wall. By setting equal distances for paired transistors, the invention creates symmetric stress conditions that compensate for thermal and mechanical stress effects, thereby improving reliability under stress while maintaining manufacturing precision.
Solution Approach 2:
The patent introduces asymmetric positioning of the insulation separation wall relative to the element separation region interface, creating a specific geometric configuration where the distance from gate oxide film to insulation separation wall is controlled independently. This asymmetric arrangement allows optimization of stress distribution to improve reliability without requiring symmetric large separation distances.
3Stability of the object's composition
If gate oxide film distance to insulation separation wall is equalized, then characteristic variations with time are reduced, but device complexity increases
Solution Approach 1:
The patent identifies and controls a single critical parameter (distance from gate oxide film to insulation separation wall) that directly affects characteristic stability. By focusing on this one parameter rather than multiple geometric constraints, the invention achieves characteristic stability while minimizing layout complexity. The equalization of this specific parameter for paired transistors provides a simple yet effective design rule.
Data Source
AI summary
Provided are a semiconductor device having small characteristic variations with time and high reliability and an in-vehicle control device using the same, the semiconductor device including a plurality of transistor elements constituting a current mirror circuit or a differential amplifier circuit that requires high relative accuracy. A semiconductor device includes a first metal-oxide-semiconductor (MOS) transistor, a second MOS transistor paired with the first MOS transistor, and insulation separation walls which insulate and separate elements from each other, wherein relative characteristics of the first MOS transistor and the second MOS transistor are in a predetermined range, the first MOS transistor and the second MOS transistor are relatively arranged in a gate width direction or a gate length direction, and distances between gate oxide films of the first MOS transistor and the second MOS transistor and the insulation separation walls facing the gate oxide films are the same as each other in a direction perpendicular to the gate width direction or the gate length direction.