Semiconductor Conductive Plug Penetrating Isolation for LDMOS
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Solution Overview
Problem
Current semiconductor structures, such as LDMOS and EDMOS, face limitations in reducing on-resistance (Ron) while maintaining or improving breakdown voltage, with only about 5% improvement in the Ron to breakdown voltage (Ron/BVD) ratio achieved through well schemes or implant optimization.
Innovation Solution
A semiconductor structure comprising a substrate with conductive type wells and a conductive plug configuration, where the plug includes a first portion connected to the gate electrode and a second portion penetrating into isolation, with the bottom surface of the second portion entirely covered by the isolation, enhancing the electrical characteristics by decreasing on-resistance and increasing breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional well schemes or implant optimization are used, then on-resistance can be reduced slightly, but breakdown voltage cannot be significantly improved, achieving only about 5% improvement in the Ron/BVD ratio
Solution Approach 1:
The conductive plug is divided into two distinct portions: a first portion that contacts the gate electrode and a second portion that extends into the isolation region. This segmentation allows each portion to serve a specific function - the first portion provides electrical connection while the second portion extends the conductive path to reduce resistance without compromising breakdown voltage.
Solution Approach 2:
The conductive plug extends in the vertical dimension by penetrating into the isolation region beneath the gate electrode. This vertical extension creates an additional conductive path that reduces on-resistance without increasing the horizontal footprint or affecting the lateral electric field distribution that determines breakdown voltage.
2Loss of energy
If the conductive plug second portion extends deeper into isolation, then on-resistance decreases further, but manufacturing complexity and precision requirements increase
Solution Approach 1:
The isolation region serves as an intermediary space that accommodates the extended portion of the conductive plug. By utilizing the existing isolation structure as a receptacle for the plug extension, the design provides a well-defined boundary that simplifies manufacturing - the plug simply needs to extend into the isolation region without requiring precise depth control, as the isolation structure itself defines the termination point.
Data Source
AI summary
A semiconductor structure comprises a substrate having a first conductive type; a deep well having a second conductive type formed in the substrate; a first well having the first conductive type and a second well having the second conductive type both formed in the deep well and the second well spaced apart from the first well; a gate electrode formed on the substrate and disposed between the first and second wells; an isolation extending down from the surface of the substrate and disposed between the gate electrode and the second well; a conductive plug including a first portion and a second portion electrically connected to each other, and the first portion electrically connected to the gate electrode, and the second portion penetrating into the isolation. The bottom surface of the second portion of the conductive plug is covered by the isolation.