Trench Gate Semiconductor Device with Variable Inclination Angles
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Solution Overview
Problem
It is challenging to form a connection region along the side surface of a trench in trench-gate-type semiconductor devices due to the narrow opening width of the trench, which limits ion implantation depth and increases the risk of crystal defects when increasing ion accelerating energy.
Innovation Solution
The semiconductor device features a trench with varying inclination angles and opening widths along its longitudinal direction, allowing for deeper ion incidence in sections where connection regions are formed and maintaining a shallow angle where channels are formed, thereby reducing crystal defects and enhancing carrier mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If ion implantation is performed at a shallow incidence angle to form a connection region along the side surface of the trench, then the connection region can be formed, but the ion implantation depth is limited and crystal defects increase when accelerating energy is increased
Solution Approach 1:
The trench is divided into multiple sections along its longitudinal direction, with different side surface inclination angles in different sections. Specifically, the trench includes a first section with a first inclination angle and a second section with a second inclination angle that is greater than the first inclination angle. This segmentation allows different regions of the trench to serve different functions: the first section maintains a shallow angle for channel formation with high carrier mobility, while the second section provides a steeper angle for effective ion implantation to form the connection region without excessive crystal defects
Solution Approach 2:
Different sections of the trench are given different local geometric properties (inclination angles) to optimize their respective functions. The first section has a smaller inclination angle optimized for carrier transport, while the second section has a larger inclination angle optimized for ion implantation efficiency. This local differentiation of geometric quality resolves the contradiction between forming connection regions and controlling implantation depth
2Length of stationary object
If accelerating energy is increased to enable deeper ion implantation, then ion implantation depth increases, but crystal defects within the semiconductor substrate increase
Solution Approach 1:
The side surface inclination angle of the trench is changed as a geometric parameter to optimize ion implantation conditions. By increasing the inclination angle in the second section, the effective implantation depth increases for a given accelerating energy, allowing adequate connection region formation without needing to excessively increase the accelerating energy, thereby reducing crystal defect formation
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 enables efficient formation of connection regions with reduced crystal defects and lower ion accelerating energy, while also increasing carrier mobility and reducing on-resistance in semiconductor devices.
Implementation Method 1
a gate electrode provided within the trench via a gate insulator film
Implementation Method 2
it is necessary to perform ion implantation of p-type impurity into the side surface of the trench through an opening of the trench
Data Source
AI summary
A semiconductor device may be provided with a semiconductor substrate, an upper electrode, a lower electrode and a gate electrode provided within a trench via a gate insulator film. The semiconductor substrate may include a p-type body layer being in contact with the upper electrode, an n-type drift layer intervening between the body layer and the lower electrode, a p-type floating region provided along a bottom surface of the trench, and a p-type connection region extending between the body layer and the floating region along a side surface of the trench. The trench may include a first section where the connection region is not provided and a second section where the connection region is provided. An inclination angle of the side surface of the trench in the second section may be greater than an inclination angle of the side surface of the trench in the first section.