SOI Trench Isolation Etching for Corner Oxidation Control
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Solution Overview
Problem
In semiconductor devices with hybrid structures, the miniaturization process leads to exposure of semiconductor substrate corners, causing significant oxidation and degradation of insulating layers, which affects the control of back-gate voltage and increases the risk of electric field concentration, resulting in reduced performance and reliability.
Innovation Solution
A method involving the formation of a semiconductor device with a SOI substrate, where a first insulating film is applied, trenches are etched, and an organic film is embedded to control the etching process, followed by anisotropic and isotropic etching to align semiconductor and insulating layer surfaces, and finally, a second insulating film is embedded to improve the curvature radius and reduce oxidation, thereby enhancing the reliability and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an etching process is performed to form trenches for element separation, then element separation is achieved, but the insulating layer is removed and corner portions of the semiconductor substrate are exposed, causing significant oxidation and degradation of capacitance
Solution Approach 1:
The patent applies a protective film to the corner portions of the semiconductor substrate before the etching process. This preliminary protective action prevents oxidation during subsequent processing steps, thereby maintaining capacitance performance while still achieving element separation through trench formation.
Solution Approach 2:
The patent selectively protects only the corner portions of the semiconductor substrate where oxidation is most problematic, rather than applying uniform protection across the entire substrate. This localized approach maintains manufacturing precision for element separation while preventing degradation at critical areas.
2Object-affected harmful factors
If the curvature radius of the semiconductor substrate at corner portions is increased to reduce oxidation, then oxidation resistance is improved, but the capacitance between the semiconductor substrate and semiconductor layer degrades
Solution Approach 1:
The protective film is applied before any etching or oxidation-prone processes, preventing oxidation at the corner portions without requiring changes to the curvature radius. This maintains the original capacitance geometry while providing oxidation resistance.
3Volume of moving object
If miniaturization is advanced to reduce device size, then device compactness is improved, but the size of the insulating layer becomes small, making capacitance degradation more significant when corner oxidation occurs
Solution Approach 1:
The protective film is applied in advance to corner portions before miniaturization-related processing steps. This ensures that even when insulating layer dimensions are reduced for miniaturization, the corner portions remain protected from oxidation, maintaining capacitance stability in compact devices.
4Loss of energy
If back-gate voltage control is implemented to suppress leak current, then power consumption is reduced, but performance deteriorates when corner oxidation degrades capacitance
Solution Approach 1:
By applying the protective film before processing, the patent prevents corner oxidation that would degrade capacitance. This maintains the effectiveness of back-gate voltage control for suppressing leak current while preserving device performance in miniaturized structures.
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 method improves the reliability and performance of semiconductor devices by maintaining uniform thickness of the semiconductor layer, reducing oxidation, and ensuring consistent capacitance, thus enhancing the control of back-gate voltage and withstanding voltage of gate insulating films.
Implementation Method 1
forming a plurality of trenches each reaching an inside of the semiconductor substrate by performing an etching process with the mask pattern as a mask
Implementation Method 2
When an oxidation treatment is performed in a state where the corner portion of the semiconductor substrate has been exposed, the corner portion of the exposed semiconductor substrate is significantly oxidized
Data Source
AI summary
After a plurality of trenches is formed in an SOI substrate, a side surface of the insulating layer is retreated from a side surface of the semiconductor layer and a side surface of the semiconductor substrate. Next, the side surface of the insulating layer is covered with an organic film and also the side surface of the semiconductor layer is exposed from the organic film by performing an anisotropic etching process to the organic film embedded into an inside of each of the plurality of trenches. Next, each of the side surface of the semiconductor layer and the side surface of the semiconductor substrate is approached to the side surface of the insulating layer by performing an isotropic etching process. Further, after the organic film is removed, an oxidation treatment is performed to each of the side surface of the semiconductor layer and the side surface of the semiconductor substrate.