Needle-Shaped Gate Trenches for Power Semiconductor Layout Density
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Solution Overview
Problem
The needle field plate structure in FETs for power electronic applications limits pitch reduction due to the requirement for stripe-shaped or grid-pattern gate trenches, increasing process complexity and cost, especially with higher gate resistance issues.
Innovation Solution
Replacing stripe-shaped or grid-pattern gate trenches with needle-shaped gate trenches and interconnecting individual gate electrodes through a metal runner network within an interlayer dielectric layer, allowing for closer placement of needle-shaped field plate trenches without the need for high-resolution and alignment accuracy tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If needle-shaped field plate trenches are used, then gate-drain charge is reduced and device FOM is improved, but pitch reduction is impeded and RDSon performance is limited
Solution Approach 1:
The patent transitions from planar stripe-shaped or grid-pattern gate trenches to needle-shaped gate trenches that extend vertically into the drift region. This dimensional change allows the gate electrodes to reach deeper into the semiconductor substrate, enabling effective field plate functionality while permitting closer spacing between structures, thus achieving pitch reduction.
Solution Approach 2:
The patent divides the gate structure into multiple discrete needle-shaped gate trenches rather than using continuous stripe-shaped trenches. This segmentation allows individual gate electrodes to be positioned independently and connected via metal runners, enabling denser layouts and reduced pitch while maintaining electrical connectivity.
2Reliability
If stripe-shaped or grid-pattern gate trenches are used with needle field plate structures, then gate-drain charge is reduced, but process complexity and cost increase
Solution Approach 1:
The patent uses needle-shaped gate trenches that extend vertically into the drift region, eliminating the need for complex stripe-shaped or grid-pattern surface trenches. This vertical configuration simplifies the lithography and etching processes while achieving the same electrical isolation and field control functions.
Solution Approach 2:
The needle-shaped gate trenches serve multiple functions: they provide gate control, act as field plates, and enable electrical isolation between adjacent structures. This multi-functionality eliminates the need for separate stripe-shaped gate trenches and field plate structures, reducing process complexity.
3Reliability
If stripe-shaped or grid-pattern gate trenches are used with needle field plate structures, then gate-drain charge is reduced, but gate resistance increases
Solution Approach 1:
The patent divides the gate structure into multiple discrete needle-shaped gate trenches connected by metal runners. This segmentation allows for optimized metal interconnect paths that reduce overall gate resistance while maintaining the electrical isolation benefits of discrete gate structures.
Solution Approach 2:
The patent combines semiconductor material for the needle-shaped gate trenches with metallic interconnect materials for the runners connecting the gate electrodes. This composite structure leverages the high breakdown field of the semiconductor and the low resistance of the metal to achieve both low gate-drain charge and low gate resistance.
Data Source
AI summary
A semiconductor device includes: a semiconductor substrate; a plurality of needle-shaped field plate trenches and a plurality of needle-shaped gate trenches formed in the semiconductor substrate and interspersed with one another; a first dielectric layer above the semiconductor substrate; a gate interconnect structure including electrically conductive lines separated from the semiconductor substrate by the first dielectric layer and first conductive vias extending through the first dielectric layer to connect the electrically conductive lines to gate electrodes in the needle-shaped gate trenches; and a field plate interconnect structure electrically isolated from the gate interconnect structure and including second conductive vias that extend through the first dielectric layer and connect to field plates in the needle-shaped field plate trenches.