FinFET Bottom Fin Width for Heat Dissipation
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Solution Overview
Problem
In semiconductor manufacturing, the reduction of critical dimension (CD) and channel length in MOSFETs leads to a worsening short-channel effect, making it difficult for the gate to control the channel, resulting in subthreshold leakage and performance degradation due to inadequate heat dissipation in FinFETs.
Innovation Solution
A semiconductor structure and method involving a fin structure with a bottom fin and a top fin, where the width of the bottom fin is greater than the top fin, enhancing heat dissipation by increasing the contact surface area with the substrate, and an isolation structure that covers the sidewall of the bottom fin to improve heat dissipation and reduce self-heating effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the channel length of MOSFET is reduced to adapt to smaller critical dimension, then the device can be scaled down, but the gate control capability deteriorates and short-channel effect increases
Solution Approach 1:
The patent transitions from a planar MOSFET to a three-dimensional FinFET structure. The fin structure extends vertically from the substrate, allowing the gate to control the channel from multiple sides (front, back, and partially from the sides), effectively adding dimensional control authority without increasing the planar channel length.
Solution Approach 2:
The fin structure is divided into a bottom fin with larger width and a top fin with smaller width. This segmentation allows the bottom fin to provide enhanced thermal dissipation and mechanical support while the top fin maintains the required electrical characteristics for gate control.
2Length of moving object
If the channel length is shortened, then device scaling is achieved, but subthreshold leakage increases due to weakened gate control
Solution Approach 1:
The vertical fin structure enables the gate to wrap around and control the channel from multiple directions, significantly improving electrostatic control and reducing subthreshold leakage that plagues short-channel planar devices.
3Length of moving object
If a standard FinFET structure is used, then device scaling is achieved, but heat dissipation performance deteriorates due to insufficient contact surface area
Solution Approach 1:
The fin is segmented into a bottom fin with larger cross-sectional area and a top fin with smaller area. The enlarged bottom fin provides increased thermal conduction path and larger contact surface with the substrate, enhancing heat dissipation capability while the top fin maintains the necessary electrical dimensions.
Solution Approach 2:
Different portions of the fin structure serve different functions: the bottom fin is optimized for thermal management with larger dimensions, while the top fin is optimized for electrical performance with smaller dimensions. This local differentiation resolves the contradiction between device scaling and heat dissipation.
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 improves heat dissipation and device performance by increasing the volume and contact surface area of the bottom fin, effectively reducing self-heating and leakage currents, thereby enhancing the overall performance of the semiconductor device.
Implementation Method 1
a bottom fin with a larger width is formed, to increase the volume of the bottom fin, and the area of a contact surface of the fin and a substrate, and to correspondingly enhance an effect of dissipating heat generated during working of a device to the substrate
Implementation Method 2
an isolation structure on the substrate exposed by a fin, where the isolation structure covers at least a sidewall of the bottom fin
Data Source
AI summary
A semiconductor structure and a method for forming a semiconductor structure are disclosed. A form of a method for forming a semiconductor structure includes: providing a base; patterning the base, to form a substrate and fins protruding out of the substrate, where each fin includes a bottom fin and a top fin located on the bottom fin, and in a direction perpendicular to an extension direction of each fin, a width of the top fin is less than a width of the bottom fin; and forming an isolation structure on the substrate exposed by a fin, where the isolation structure covers at least a sidewall of the bottom fin, and a top of the isolation structure is lower than a top of the fin. In the present disclosure, a bottom fin with a larger width is formed, to increase the volume of the bottom fin, and the area of a contact surface of the fin and the substrate, and to correspondingly enhance an effect of dissipating heat generated during working of a device to the substrate, thereby improving the heat dissipation performance of the device, and to correspondingly improving a self-heating effect of the device, so that the device performance is further improved.