Trench Gate Oxide Segmentation for Leakage Reduction
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Solution Overview
Problem
Semiconductor devices with trench technology face reliability issues due to defects in the thin gate oxide layer, leading to increased leakage currents and reduced reliability, especially in applications requiring fast switching characteristics.
Innovation Solution
A method for manufacturing semiconductor devices involves forming a gate insulating layer that extends from the first to the second trench section, with a constant thickness across the transition between the field oxide and gate oxide sections, and a conductive layer is formed on this insulating layer, ensuring the gate oxide layer maintains a consistent thickness to reduce leakage currents and enhance reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a thin gate oxide layer is used to enable fast switching, then switching speed is improved, but leakage currents increase and reliability deteriorates
Solution Approach 1:
The gate structure is divided into two distinct sections: a first gate section with a first gate oxide layer and a second gate section with a second gate oxide layer. This segmentation allows each section to have optimized oxide thickness for its specific function, resolving the contradiction between fast switching and low leakage.
Solution Approach 2:
Different regions of the gate have different oxide layer thicknesses tailored to their specific requirements. The first gate section has a thinner oxide layer optimized for fast switching, while the second gate section has a thicker oxide layer optimized for low leakage currents, achieving local optimization of both contradictory requirements.
2Use of energy by moving object
If a thin gate oxide layer is used, then capacitance is reduced for fast switching, but defects in the oxide layer increase leakage currents
Solution Approach 1:
The gate oxide structure is segmented into two sections with different thicknesses. The first section has thinner oxide for low capacitance and fast switching, while the second section has thicker oxide to prevent leakage currents caused by defects, thus resolving the contradiction between energy efficiency and harmful leakage.
Solution Approach 2:
The second gate oxide layer acts as an intermediary protective layer that prevents leakage currents from reaching the active switching region. This intermediary structure allows the first thinner oxide layer to maintain low capacitance while the second layer blocks harmful leakage paths.
3Ease of manufacture
If the gate oxide layer thickness varies at the transition between field oxide and gate oxide sections, then manufacturing is simplified, but short-circuits increase and breakdown voltage decreases
Solution Approach 1:
A preliminary thick gate oxide layer is formed across the entire gate region before patterning. This preliminary action ensures uniform thickness and prevents short-circuits at transitions, after which the oxide is selectively removed to create the final two-section structure with the required thickness variation.
Solution Approach 2:
The second gate oxide layer serves as a cushioning protective layer at the transition region between field oxide and gate oxide sections. This beforehand cushioning prevents short-circuits and maintains breakdown voltage by providing continuous insulation where thickness transitions occur.
Data Source
AI summary
A semiconductor and method for manufacturing a semiconductor device. In one embodiment the method includes providing a semiconductor substrate with a first substrate surface and at least one trench having at least one trench surface. The trench extends from the first substrate surface into the semiconductor substrate. The trench has a first trench section and a second trench section. The trench surface is exposed in an upper portion of the first and second trench sections and covered with a first insulating layer in a lower portion. A second insulating layer is formed at least on the exposed trench surface in the upper portion. A conductive layer is formed on the second insulating layer at least in the upper portion, wherein the second insulating layer electrically insulates the conductive layer from the semiconductor substrate. The conductive layer is removed in the first trench section without removing the conductive layer in the second trench section.