Sacrificial Gate Oxide Process for Higher Drain-Gate Breakdown
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Solution Overview
Problem
Current manufacturing processes for power semiconductor devices result in a divot near the oxide diffusion/shallow trench isolation region, leading to a thinner high voltage gate oxide region, which severely degrades the drain to gate breakdown voltage, limiting their use for high voltage operations.
Innovation Solution
A mask-free process is employed that utilizes a sacrificial oxide layer formed by in-situ steam generation (ISSG) to prevent the formation of a thinner gate oxide region, improving the drain to gate breakdown voltage by over 30% without requiring additional masks or thermal budgets, and can simultaneously manufacture core, input/output, and high voltage devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current manufacturing processes are used, then production efficiency is maintained, but drain to gate breakdown voltage is severely degraded
Solution Approach 1:
A sacrificial oxide layer is formed in advance on the substrate before subsequent processing steps. This preliminary oxide layer prevents the formation of divots during later etching and fabrication processes, thereby preserving gate oxide thickness and improving drain to gate breakdown voltage without requiring additional masks or thermal budgets
Solution Approach 2:
The sacrificial oxide layer acts as an intermediary protective layer between the substrate and the divot-forming processes. It temporarily occupies the space that would otherwise become divots, and is later removed to reveal a flat surface with proper gate oxide thickness, thus mediating between the conflicting requirements of maintaining production efficiency and improving breakdown voltage
2Reliability
If a thicker gate oxide region is formed, then drain to gate breakdown voltage is improved, but gate oxide thickness uniformity is compromised
Solution Approach 1:
The sacrificial oxide layer is applied selectively to specific regions of the substrate where divot formation would occur, such as near oxide diffusion and shallow trench isolation regions. This localized approach ensures that the gate oxide thickness is maintained in critical areas without affecting the overall uniformity of the gate oxide layer across the entire device
Solution Approach 2:
The sacrificial oxide layer is formed beforehand in the regions that are prone to divot formation. This preliminary action ensures that when subsequent processing occurs, these specific areas maintain the correct oxide thickness, thereby achieving local quality improvement without compromising global uniformity
3Reliability
If additional masks or thermal budgets are used, then drain to gate breakdown voltage can be improved, but process complexity and manufacturing cost increase
Solution Approach 1:
The sacrificial oxide layer serves multiple functions within the existing manufacturing process flow: it prevents divot formation, maintains gate oxide thickness, and can be integrated with standard oxidation processes already used for other device components. This multi-functionality allows improvement in breakdown voltage without adding process complexity or requiring additional masks
Solution Approach 2:
The sacrificial oxide layer is formed using standard in-situ steam generation processes that are already part of the manufacturing toolkit. The process leverages existing equipment and methodologies, allowing the solution to improve drain to gate breakdown voltage without requiring new process equipment or additional thermal budgets
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 method enhances the drain to gate breakdown voltage by more than two volts or 30% over current processes, enabling the use of semiconductor devices for high voltage operations without affecting the performance of core or input/output devices.
Implementation Method 1
a sacrificial oxide layer formed by in-situ steam generation (ISSG) to prevent the formation of a thinner gate oxide region
Data Source
AI summary
A semiconductor device may include a first device on a first portion of a substrate, a second device on a second portion of the substrate, and a third device on a third portion of the substrate. The third device may include an oxide layer that is formed from an oxide layer that is a sacrificial oxide layer for the first device and the second device. The third device may include a gate provided on the oxide layer, a set of spacers provided on opposite sides of the gate, and a source region provided in the third portion of the substrate on one side of the gate. The third device may include a drain region provided in the third portion of the substrate on another side of the gate, and a protective oxide layer provided on a portion of the gate and a portion of the drain region.