LDMOS Transistor TSV Source Coupling for High-Frequency Performance
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Solution Overview
Problem
There is a need for improved connection methods between the source and the rear surface of the substrate in lateral transistor devices, such as LDMOS transistors, to enhance performance at higher frequencies, including microwave frequencies, as existing connections may not adequately support the required electrical coupling.
Innovation Solution
A semiconductor device with a through substrate via (TSV) and a conductive layer that extends from the sidewalls of the TSV onto the front surface, electrically coupling the intrinsic source to the rear surface, using high purity copper and Ti or TiN layers, and a method involving blind via formation, conductive layer deposition, and substrate surface processing to achieve a robust and efficient connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional connection methods (sinker structure or TSV) are used to couple the source to the rear side of the substrate, then electrical coupling is achieved, but parasitic effects remain significant and performance at high frequencies is limited
Solution Approach 1:
The patent transitions from conventional planar or vertical connections to a three-dimensional conductive structure where the first conductive layer lines the sidewalls of the TSV and extends onto the front surface, creating a distributed conductive path that reduces parasitic inductance and resistance through spatial optimization
Solution Approach 2:
The patent employs a composite conductive structure combining multiple materials (copper for low resistance, Ti/TiN for adhesion and barrier properties) in the conductive layer and TSV configuration, optimizing both electrical performance and mechanical reliability
2Productivity
If the conductive layer is deposited onto sidewalls of TSV and extends onto the front surface, then parasitic effects are reduced and high-frequency performance is enhanced, but device structure and manufacturing process become more complex
Solution Approach 1:
The first conductive layer serves multiple functions simultaneously: it provides electrical connection through the TSV, reduces parasitic effects through its extended configuration, and acts as an adhesion layer between different materials, consolidating multiple functions into a single structural element
3Reliability
If high purity copper and Ti or TiN layers are used in the conductive structure, then electrical conductivity and adhesion are improved, but manufacturing process complexity increases
Solution Approach 1:
The Ti or TiN layer is deposited as a preliminary adhesion and barrier layer before the copper fill process, preparing the substrate surface in advance to ensure proper copper adhesion and prevent copper diffusion into the substrate, thereby simplifying subsequent manufacturing steps
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a reliable and efficient electrical coupling between the transistor source and the rear surface, reducing parasitic effects and enhancing the performance of LDMOS transistors at high frequencies by creating a redistribution path with a vertical and lateral conductive structure, suitable for high-frequency applications like RF power amplifying circuits.
Implementation Method 1
A first conductive layer lines sidewalls of the through substrate via and extends from the through substrate via onto the front surface of the semiconductor substrate. The first conductive layer is electrically coupled with the intrinsic source.
Data Source
AI summary
In an embodiment, a semiconductor device includes a semiconductor substrate having a front surface, a lateral transistor arranged in the front surface of the semiconductor substrate and having an intrinsic source, and a through substrate via. A first conductive layer lines side walls of the through substrate via and extends from the through substrate via onto the front surface of the semiconductor substrate and is electrically coupled with the intrinsic source of the lateral transistor.