String Driver Isolation Layout for Dense High-Voltage Arrays
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Solution Overview
Problem
Conventional string driver devices in wafer-on-wafer packaging face challenges in increasing density and performance due to limitations in reducing widthwise pitch and active area dimensions, leading to reduced transistor drive current, breakdown voltage, and leakage issues caused by shallow-trench isolation and punch-through effects.
Innovation Solution
The introduction of string driver devices with shallow trench isolation (STI) regions adjacent to channel regions and a grounding network connected to body/well regions, providing biasing voltage to inhibit transistor body effects, while using through-silicon isolation (TSI) for electrical isolation and integrating high voltage string drivers into the POC F2B WOW bonding scheme.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If widthwise pitch and active area dimensions are reduced to increase density, then device density is improved, but transistor drive current and breakdown voltage are reduced
Solution Approach 1:
The patent introduces through-silicon isolation (TSI) regions that extend vertically through the entire substrate thickness, adding a third dimension (depth) to the isolation structure. This vertical dimension allows for effective electrical isolation without further reducing the horizontal active area dimensions, thereby maintaining transistor drive current while achieving higher device density through more efficient space utilization in the vertical direction.
Solution Approach 2:
The TSI regions act as intermediary structures between adjacent active regions, providing a dedicated isolation path that prevents electrical interference and punch-through effects. This intermediary isolation mechanism allows for reduced spacing between active regions (increasing density) while maintaining adequate electrical separation to preserve transistor performance characteristics.
2Quantity of substance
If widthwise pitch and active area dimensions are reduced to increase density, then device density is improved, but breakdown voltage is reduced
Solution Approach 1:
The through-silicon isolation regions extend vertically through the entire substrate thickness, creating a three-dimensional isolation barrier. This vertical extension provides a longer isolation path that effectively blocks electrical breakdown paths between adjacent high-voltage structures, maintaining breakdown voltage even when horizontal spacing is reduced for higher density.
Solution Approach 2:
The patent employs composite isolation structures combining shallow trench isolation (STI) regions at the surface level with deeper through-silicon isolation (TSI) regions extending through the substrate. This multi-layer composite isolation approach provides enhanced electrical separation and breakdown protection compared to single-level isolation, enabling high-density layouts while maintaining high-voltage performance.
3Ease of manufacture
If shallow-trench isolation is used, then manufacturing is simplified, but leakage issues and punch-through effects occur
Solution Approach 1:
The isolation structure is segmented into two distinct components: shallow trench isolation (STI) regions near the surface and deeper through-silicon isolation (TSI) regions extending through the substrate. This segmentation allows the STI to provide easy-to-manufacture surface isolation while the deeper TSI regions provide additional leakage and punch-through protection, combining manufacturing simplicity with enhanced electrical isolation performance.
Solution Approach 2:
The patent enhances the conventional two-dimensional shallow trench isolation by adding a vertical dimension with through-silicon isolation regions that penetrate deep into the substrate. This vertical extension maintains the manufacturing simplicity of trench-based isolation while dramatically improving isolation effectiveness by blocking leakage and punch-through paths that extend deeper into the device structure.
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
This configuration maintains high breakdown voltage, good dielectric isolation, and proper body control, enabling higher density and performance with reduced leakage and increased drive current, thus addressing the limitations of conventional methods.
Implementation Method 1
a plurality of through silicon isolation (TSI) regions are formed above the substrate and disposed between neighboring active regions of the plurality of active regions
Implementation Method 2
a grounding network is formed connected to body/well regions of the string driver array blocks, the grounding network providing a biasing voltage to inhibit string driver transistor body effects
Data Source
AI summary
A string driver device including a substrate; and a plurality of string driver array blocks that are disposed above the substrate, each of the plurality of string driver array blocks including a plurality of active regions that are parallelly aligned along a length direction, a plurality of shared gates that are disposed above the plurality of active regions and along a width direction, the width direction being perpendicular to the length direction, a through silicon isolation (TSI) region that surrounds the plurality of active regions on the substrate and that is disposed between neighboring active regions of the plurality of active regions, and a plurality of shallow trench isolation (STI) regions that are disposed adjacent to one or more channel regions of each of the plurality of active regions and below the plurality of shared gates respectively.