SOI Semiconductor Device Noise Isolation via Segmented Substrate
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Solution Overview
Problem
Noise propagation from a circuit with a large reference potential to a circuit with a small reference potential remains a challenge even when they are insulated on a silicon-on-insulator (SOI) substrate, as the semiconductor substrate acts as a conduit for noise transmission.
Innovation Solution
A semiconductor device is designed with a buried insulating layer and an isolation insulating layer that reaches the buried insulating layer, separating the first and second circuit forming regions, and the semiconductor substrate is not electrically connected to the electrode pads, thereby preventing noise propagation through the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If two circuits with different reference potentials are formed on the same semiconductor substrate, then integration is achieved, but noise propagates from one circuit to the other through the substrate
Solution Approach 1:
The semiconductor substrate is divided into multiple isolated regions by burying isolation insulating layers that extend from the semiconductor layer down to the buried insulating layer. This segmentation physically separates the first circuit forming region and second circuit forming region, preventing noise propagation through the substrate while maintaining integration on the same chip.
Solution Approach 2:
Isolation insulating layers are introduced as intermediary structures between the first and second circuits. These insulating layers act as mediators that block the propagation path of noise through the semiconductor substrate, allowing both circuits to coexist with different reference potentials without mutual interference.
2Object-affected harmful factors
If circuits are insulated from each other in the semiconductor layer, then some noise isolation is achieved, but noise still propagates through the semiconductor substrate
Solution Approach 1:
The isolation approach is extended from the lateral dimension (insulation within the semiconductor layer) to the vertical dimension by burying isolation insulating layers that reach from the semiconductor layer down to the buried insulating layer. This multi-dimensional isolation strategy completely blocks noise propagation paths through the substrate.
3Object-affected harmful factors
If the semiconductor substrate is not electrically connected to electrode pads, then noise propagation is suppressed, but substrate potential control becomes challenging
Solution Approach 1:
Different regions of the semiconductor device are given different electrical connection characteristics. The first and second circuit forming regions are locally isolated from the substrate to suppress noise, while specific regions can be selectively connected to the substrate potential if needed for other functions. This local differentiation allows noise suppression without completely sacrificing substrate potential control capability.
Data Source
AI summary
A semiconductor chip includes a first circuit and a second circuit having different reference potentials. A first potential which is a reference potential of the first circuit is applied to the semiconductor chip through any of plural lead terminals, and a second potential which is a reference potential of the second circuit is applied to the semiconductor chip through any of plural lead terminals. A substrate of the semiconductor chip has a structure in which a buried insulating layer and a semiconductor layer of a first conductivity type are laminated on a semiconductor substrate such as a SOI substrate. A fixed potential is applied to the semiconductor substrate through a die pad and a lead terminal for a substrate potential. The fixed potential is applied to the semiconductor chip through a different route from the reference potential of the first circuit and the reference potential of the second circuit.