Silicon Super Junction Structure With Liner-Filled High-Aspect Trenches
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Solution Overview
Problem
Conventional semiconductor technologies face challenges in scaling high aspect ratio power devices due to issues with maintaining uniformity and preventing defects in feature formation and filling, leading to tapered sidewalls and seam/void formation in recessed features.
Innovation Solution
The approach involves forming a thin epitaxial liner within a wider trench feature, allowing for the deposition of narrow P-type regions between N-type regions without seams or voids, thereby increasing aspect ratios and preventing defects by changing the formation process to maintain uniform coverage and fill.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If conventional etch-and-fill methods are used to form high aspect ratio features, then device scaling is achieved, but tapered sidewalls and seam/void formation occur in recessed features
Solution Approach 1:
A liner layer is formed on the substrate before the recessed features are etched. This preliminary action provides a foundation that enables subsequent uniform filling of high aspect ratio features, preventing the tapered sidewalls and voids that would otherwise occur with conventional direct etch-and-fill methods
Solution Approach 2:
The liner layer acts as an intermediary between the substrate and the fill material. This intermediate layer facilitates uniform material deposition in high aspect ratio features by providing a nucleation surface and controlling the fill process, thereby eliminating seams and voids while maintaining straight sidewalls
2Area of moving object
If device features are made smaller to reduce device size, then integration density increases, but maintaining dimensions during processing becomes more challenging
Solution Approach 1:
The formation process is changed from direct etch-and-fill to a method involving preliminary liner formation. This parameter change in the manufacturing process enables precise dimensional control of small features by providing a controlled interface that guides subsequent material deposition, maintaining feature dimensions even as device size decreases
3Ease of manufacture
If backfilling of recessed features is performed without specialized processes, then process simplicity is maintained, but seams and voids form in the filled features
Solution Approach 1:
The liner layer is formed as a preliminary step before backfilling recessed features. This preliminary action transforms a complex defect-prone process into a simpler, more reliable process by providing a foundation that enables uniform fill material deposition, eliminating the need for specialized multi-step filling procedures while preventing seams and voids
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 enables the creation of high-voltage super junction devices with increased aspect ratios and reduced defects, achieving higher breakdown voltages while maintaining device width, overcoming limitations of traditional etch-and-fill methods.
Implementation Method 1
forming a thin epitaxial liner within a wider trench feature, allowing for the deposition of narrow P-type regions between N-type regions
Data Source
AI summary
A super junction device with an increased voltage rating may be formed by decreasing the width of the P-type region and increasing the doping concentration, while also increasing the height of the overall device. However, instead of etching a trench in the N-type material to fill with the P-type material, a trench may be etched for both the P-type region and an adjacent N-type region. This allows the height of the overall device to be increased while maintaining a feasible aspect ratio for the trench. The P-type material may then be formed as a sidewall liner on the trench that is relatively thin compared to the remaining width of the trench. The trench may then be filled with N-type material such that the P-type region fills the space between the N-type regions without any voids or seams, while having a width that would be unattainable using traditional etch-and-fill methods for the P-type region alone.