Trench Gate Semiconductor Device Bottom Electrode Feedback Capacity
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Solution Overview
Problem
The existing trench gate-type semiconductor devices face challenges in reducing feedback capacity while maintaining low manufacturing costs, as thickening the oxide film on the recess bottom to reduce feedback capacity complicates the manufacturing process and increases on-resistance when the recess width is widened.
Innovation Solution
A trench gate-type semiconductor device design where the oxide film is thickened only on the bottom surface of the recess, with a bottom electrode separated from the gate electrode, allowing for reduced feedback capacity and simplified manufacturing by avoiding the need for repeated etching and oxidation processes, and the recess width is widened to enhance withstanding voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the oxide film is thickened on the bottom part of the recess to reduce feedback capacity, then the feedback capacity is reduced, but the manufacturing process becomes complicated and costs increase
Solution Approach 1:
The patent applies local quality by forming the oxide film with different thicknesses at different locations within the recess. Specifically, the oxide film is made thicker at the bottom surface of the recess and thinner on the side surfaces. This localized variation in oxide film thickness allows the bottom electrode to be electrically isolated from the drain layer (reducing feedback capacity) while maintaining proper electrical contact between the gate electrode and the semiconductor layer, thereby avoiding the need for complex repeated etching and oxidation processes.
2Reliability
If the recess width is widened to lower on-resistance, then the on-resistance is reduced, but the feedback capacity increases
Solution Approach 1:
The patent resolves this contradiction by implementing local quality through the non-uniform oxide film thickness. The thicker oxide film at the bottom of the recess provides electrical isolation between the bottom electrode and the drain layer, effectively reducing feedback capacity even when the recess width is widened. Meanwhile, the thinner oxide film on the side surfaces maintains proper gate control and channel formation, allowing the recess to be widened for lower on-resistance and higher withstanding voltage.
3Object-affected harmful factors
If the oxide film is uniformly thickened throughout the recess, then the feedback capacity is reduced, but the interface characteristic with semiconductor layers deteriorates
Solution Approach 1:
The patent applies local quality by creating a non-uniform oxide film thickness distribution. The oxide film is formed thicker at the bottom surface of the recess where electrical isolation is needed, and thinner on the side surfaces where good interface characteristics with semiconductor layers are required. This localized differentiation allows the thicker bottom oxide to reduce feedback capacity while the thinner side oxide preserves favorable interface characteristics for proper device operation.
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
The design effectively reduces feedback capacity and maintains low manufacturing costs by simplifying the process and improving withstanding voltage through the strategic placement of the bottom electrode and widening the recess width, while also lowering on-resistance.
Implementation Method 1
the oxide film 186 is formed to be thin by a thermal oxidation causing an interface characteristic with the semiconductor layers (the p−-type layer 183 and the like) to be particularly favorable
Data Source
AI summary
A semiconductor device includes: a first semiconductor region; a second semiconductor region; a third semiconductor region; a fourth semiconductor region; an insulation film, which is arranged on an inner wall of a recess extending from an upper surface to the second semiconductor region; a control electrode, which is arranged on a region of the insulation film on a side surface of the recess; a first main electrode connected to the first semiconductor region; a second main electrode connected to the fourth semiconductor region; and a bottom electrode, which is arranged on the insulation film and is electrically connected to the second main electrode, and a length of the recess in an extension direction thereof is equal to or larger than a width of the recess, and the width of the recess is wider than an interval between the adjacent recesses.