Semiconductor Logic Circuit Using N-Channel Transistors and Capacitor
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Solution Overview
Problem
The fabrication of p-channel oxide semiconductor transistors is difficult, leading to increased costs and reduced productivity when both p-channel and n-channel transistors are fabricated on the same substrate, resulting in a logic circuit with reduced output voltage due to transistors of the same conductivity type.
Innovation Solution
A semiconductor device is designed with a configuration that includes multiple n-channel transistors and a capacitor, where the channel length of one transistor is shorter and the channel width is longer than another, allowing for high productivity and low power consumption, and utilizing oxide semiconductors with back gates to enhance mobility and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If both p-channel and n-channel transistors are fabricated separately on one substrate, then logic circuits with both conductivity types can be constructed, but the number of process steps increases and productivity decreases
Solution Approach 1:
The invention inverts the conventional approach by fabricating only n-channel transistors on the substrate, rather than attempting to fabricate both p-channel and n-channel transistors. This inversion simplifies the fabrication process while the capacitor circuit configuration compensates for the missing p-channel functionality, thereby improving productivity without sacrificing logic circuit versatility
2Adaptability or versatility
If both p-channel and n-channel transistors are fabricated on the same substrate, then logic circuits with both conductivity types can be constructed, but fabrication cost increases
Solution Approach 1:
The invention inverts the conventional approach by fabricating only n-channel transistors on the substrate, rather than attempting to fabricate both p-channel and n-channel transistors. This inversion simplifies the fabrication process while the capacitor circuit configuration compensates for the missing p-channel functionality, thereby improving productivity without sacrificing logic circuit versatility
3Productivity
If transistors with the same conductivity type are used to construct logic circuits, then productivity is improved, but output voltage drops due to threshold voltage losses
Solution Approach 1:
The invention changes the circuit configuration parameters by introducing a specific capacitor connection between the gate and drain of the n-channel transistor. This parameter change allows the circuit to compensate for threshold voltage losses and achieve full swing output voltage, thereby maintaining high productivity while resolving the output voltage degradation issue
Data Source
AI summary
Decrease of the output voltage of the logic circuit is inhibited by raising the gate voltage using a capacitor. In a first transistor, a drain and a gate are electrically connected to a first wiring, and a source is electrically connected to a first node. In a second transistor, a drain is electrically connected to the first node, a source is electrically connected to a second wiring, and a gate is electrically connected to a second node. In a third transistor, a drain is electrically connected to a third wiring, and a source is electrically connected to a third node, and a gate is electrically connected to the first node. In a fourth transistor, a drain is electrically connected to the third node, a source is electrically connected to a fourth wiring, and a gate is electrically connected to the second node. In a capacitor, one electrode is electrically connected to the first node, and the other electrode is electrically connected to the third node. OS transistors are preferably used as the transistors above.