Power Switch Circuit Layout Using Overlapping Supply Lines
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Solution Overview
Problem
When a power switch circuit in semiconductor devices has a large layout size due to large transistors, it fails to fit between power supply wiring disposed at a predetermined pitch, leading to competition with virtual power supply lines formed using metal wiring layers close to the semiconductor substrate.
Innovation Solution
The semiconductor device incorporates a design where power supply lines, including virtual power supply lines, are formed using metal wiring layers close to the semiconductor substrate, while ensuring that these lines do not compete with internal wiring in the power switch circuit by strategically arranging the wiring in different layers and directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the transistor size in the power switch circuit is increased to enhance power supply capability, then the power supply capability is improved, but the layout size of the power switch circuit becomes large and cannot fit between power supply wiring disposed at a predetermined pitch
Solution Approach 1:
The invention utilizes multiple wiring layers (first wiring layer and second wiring layer) to arrange power supply lines and internal wirings in different spatial dimensions. By forming power supply lines in one layer and internal wirings in another layer, the circuit achieves sufficient power supply capability without requiring a large planar layout area, thus fitting within the predetermined pitch constraints.
2Power
If virtual power supply lines are formed using metal wiring layers close to the semiconductor substrate, then sufficient power supply voltage can be provided to circuit blocks, but wiring in the power switch circuit in the same layer competes with the virtual power supply line
Solution Approach 1:
The invention resolves wiring competition by assigning different functions to different wiring layers. The first wiring layer (closer to the substrate) is dedicated to virtual power supply lines, while the second wiring layer (above the first layer) is used for internal wirings of the power switch circuit. This vertical separation eliminates lateral competition for routing space while maintaining efficient power delivery to circuit blocks.
Data Source
AI summary
A semiconductor device includes first and second power supply lines formed in a first wiring layer and extending in a first direction; third and fourth power supply lines formed in a second wiring layer, extending in a second direction, and connected to the first and second power supply lines, respectively; a fifth power supply line formed in the first wiring layer; and a first power switch circuit including a transistor provided between the first and fifth power supply lines. The transistor overlaps at least one of the third and fourth power supply lines. The first power switch circuit includes first and second wirings formed in the second wiring layer, extending in the second direction, not overlapping the third and fourth power supply lines, and connected to a source of the transistor and the fifth power supply line, and to a drain and the third power supply line, respectively.