FinFET Isolation Structure for Heat Dissipation
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Solution Overview
Problem
The performance of FinFETs is adversely affected by a short channel effect and leakage current due to the reduced control ability of traditional planar semiconductor devices, leading to poor heat dissipation and self-heating effects, which degrade the electrical performance of semiconductor devices.
Innovation Solution
A semiconductor device and fabrication method that includes a semiconductor substrate with a middle region and an edge region, where the surface of the middle region is higher than the edge region, featuring discrete fins with a thinner isolation structure in the middle region for improved heat dissipation and a thicker structure in the edge region for field isolation, reducing self-heating and enhancing device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a traditional planar semiconductor device is used, then the device structure is simple, but the control ability of the channel current is reduced and short channel effect occurs
Solution Approach 1:
The patent transitions from a planar (2D) device structure to a FinFET structure with vertical fins extending from the substrate. This dimensional change creates a three-dimensional channel that provides multi-gate control, significantly improving control ability over the channel current while maintaining manufacturing feasibility through adapted fabrication processes.
Solution Approach 2:
The device is segmented into multiple vertical fins rather than a single planar channel. Each fin acts as an independent current path with its own gate control, allowing the total channel current to be controlled through multiple discrete structures. This segmentation enables better electrostatic control and reduces short channel effects.
2Reliability
If FinFET structure is adopted to overcome short channel effect, then the control ability of channel current is improved, but leakage current increases and heat dissipation deteriorates
Solution Approach 1:
The isolation structure is designed with varying thicknesses at different locations: thinner isolation between adjacent fins in the same device to reduce leakage, and thicker isolation between different devices to provide electrical separation. This local differentiation of isolation quality addresses both leakage current and heat dissipation issues in their respective regions.
Solution Approach 2:
The isolation structure serves as an intermediary element between the fins and between devices. It provides electrical isolation to suppress leakage current while its thermal properties facilitate heat dissipation from the active fin regions, mediating between the conflicting requirements of electrical performance and thermal management.
3Ease of manufacture
If uniform isolation structure is used across the device, then manufacturing is simplified, but heat dissipation is insufficient and self-heating effect occurs
Solution Approach 1:
The isolation structure implements local quality variations with different thicknesses in different regions: thinner isolation layers positioned to facilitate heat dissipation pathways, and thicker isolation layers where electrical separation is prioritized. This non-uniform design optimizes both thermal management and electrical isolation without requiring completely separate fabrication processes.
Data Source
AI summary
Semiconductor devices are provided. An exemplary semiconductor device includes a semiconductor substrate having a first region. The first region includes a first middle region and a first edge region adjacent to and surrounding the first middle region; and a surface of the first middle region of the semiconductor substrate is higher than a surface of the first edge region of the semiconductor substrate. The semiconductor device also includes a plurality of first fins discretely formed on the first middle region of the semiconductor substrate; and an isolation structure formed on the first middle region of the semiconductor substrate and the first edge region of the semiconductor substrate and covering portions of sidewall surfaces of the first fins.