Convex Shoulder Mesa Structure for Semiconductor Electrode Connection
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Solution Overview
Problem
Conventional semiconductor devices with gate trenches and mesa portions face challenges in achieving effective electrode connections due to limited surface width, leading to difficulties in miniaturization and threshold voltage control.
Innovation Solution
The semiconductor device incorporates a mesa portion with a shoulder portion that has an outwardly convex shape, allowing for increased effective surface width for electrode connections and deeper emitter region extension, facilitating easier impurity implantation and improved threshold voltage control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the mesa portion width is reduced for miniaturization, then the device size is reduced, but the effective width for electrode connections becomes insufficient
Solution Approach 1:
The invention transitions from a conventional planar mesa structure to a three-dimensional structure with an outwardly convex shoulder portion. This dimensional change allows the mesa portion to provide sufficient electrode connection area at the shoulder while maintaining a compact overall device footprint, effectively resolving the contradiction between miniaturization and connection area requirements.
Solution Approach 2:
The shoulder portion is designed with an outwardly convex curved shape rather than a straight or angled configuration. This curvature maximizes the effective width available for electrode connections at the mesa end portion, allowing compact device dimensions while ensuring adequate connection area for reliable electrode attachment.
2Manufacturing precision
If the emitter region is extended deeper for better threshold voltage control, then the threshold voltage controllability is improved, but the impurity implantation process becomes more difficult
Solution Approach 1:
The gate trench portion is formed first before the emitter region implantation. This preliminary action creates a defined target area and allows for precise alignment during subsequent implantation steps, enabling deep emitter extension with accurate impurity placement while maintaining manufacturing feasibility through sequential process planning.
Solution Approach 2:
The emitter region is designed with non-uniform depth characteristics - extending deeper at the gate trench side compared to the center of the mesa portion. This local variation in emitter depth allows optimized threshold voltage control at critical regions while maintaining a manageable overall structure that remains feasible for impurity implantation through targeted doping approaches.
3Stability of the object's composition
If the shoulder portion has a large radius of curvature for smooth shape, then the shape variation is reduced, but the electric field concentration increases
Solution Approach 1:
The radius of curvature of the shoulder portion is precisely controlled within a specific range (0.5 μm to 2 μm) rather than being maximized or minimized. This parameter optimization balances two competing requirements: sufficient curvature to reduce shape variation and manufacturing tolerance sensitivity, while limiting the radius to prevent excessive electric field concentration that would occur with very large curvature radii.
Data Source
AI summary
A semiconductor device is provided. The semiconductor device includes a mesa portion provided inside the semiconductor substrate and in contact with the gate trench portion, wherein the mesa portion has, at an end portion of an upper surface thereof, a shoulder portion in contact with the gate trench portion, the shoulder portion has an outwardly convex shape, the mesa portion has a first conductivity type emitter region that: is in contact with the gate trench portion and positioned between the upper surface of the semiconductor substrate and the drift region; and has a doping concentration higher than the drift region, a lower end of the emitter region at a position in contact with the gate trench portion is located at a deeper position in the depth direction than a lower end of the emitter region at a middle, in the transverse direction, of the mesa portion.