Low-Temperature Trench Passivation for Damage-Free Semiconductor Surfaces
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Solution Overview
Problem
Traditional semiconductor processing methods often result in damaged trench surfaces during etching, leading to increased defect densities and reduced charge mobilities in devices like optoelectronic devices, due to incomplete passivation and contamination.
Innovation Solution
A method involving a dry oxide process followed by selective removal and epitaxial passivation layer formation, using a low-temperature process to create a homogeneous passivation region with controlled oxidation thickness and high conformality, which repairs trench surfaces and reduces defects without adding extra material interfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional etching processes are used to form trenches, then trench structures can be created, but the trench surfaces become damaged and contaminated
Solution Approach 1:
A preliminary cleaning process is performed before trench formation to prevent contamination, and a passivation layer is formed after etching to repair surface damage. This preliminary and follow-up actions approach addresses the surface quality issue without compromising the ease of trench formation.
Solution Approach 2:
A passivation layer is introduced as an intermediary between the damaged trench surface and the device structures. This layer mediates the harmful effects of surface damage and contamination, restoring surface quality while maintaining the benefits of traditional etching processes.
2Manufacturing precision
If precleaning processes are applied to repair trench surfaces, then some damage can be removed, but defect densities remain increased and charge mobilities remain reduced
Solution Approach 1:
The passivation layer serves as an intermediary that completely passivates the trench surface, preventing the residual defects from affecting device performance. This intermediary layer restores charge mobility by isolating the damaged surface from active device regions.
Solution Approach 2:
The cleaning and passivation processes use controlled chemical parameters to selectively remove damaged surface layers while preserving the underlying substrate. By adjusting process parameters such as oxidation temperature and duration, the method achieves complete defect removal without compromising device performance.
3Productivity
If high aspect ratio trenches are etched, then device density is improved, but surface damage and contamination increase
Solution Approach 1:
Preliminary cleaning before etching and passivation after etching are applied to high aspect ratio trenches. These preliminary and follow-up actions ensure that even the difficult-to-reach surfaces of high aspect ratio trenches are properly cleaned and passivated, enabling high device density without excessive surface damage.
Solution Approach 2:
The passivation layer acts as an intermediary that protects the deeply etched trench surfaces in high aspect ratio structures. This layer is particularly effective for high aspect ratio trenches where surface damage is most severe, as it provides complete passivation throughout the entire trench depth.
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 approach significantly minimizes surface damage, reduces noise and leakage, and allows for high-aspect-ratio trench formation with improved performance by forming damage-free trench structures using low thermal budgets, enhancing charge mobility and reducing optical penalties.
Implementation Method 1
forming an oxide layer on surfaces of the trench using a dry oxide process
Implementation Method 2
forming a passivation layer on surfaces of the trench to form a homogeneous passivation region as part of the substrate material wherein the passivation layer is an epitaxial layer formed of single crystals
Implementation Method 3
performing a charge diffusion process to embed the additional dopant into the substrate material
Data Source
AI summary
Methods for forming a trench structure with passivated surfaces. In some embodiments, a method of forming a trench structure may include etching a trench into a substrate material of the substrate, forming an oxide layer on surfaces of the trench using a dry oxide process at a temperature of less than approximately 450 degrees Celsius, selectively removing the oxide layer from surfaces of the trench, and forming a passivation layer on surfaces of the trench to form a homogeneous passivation region as part of the substrate material using a low temperature process of less than approximately 450 degrees Celsius.