Trench Filling with Dopant Diffusion for Void-Free Semiconductor Structures
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Solution Overview
Problem
As semiconductor elements are miniaturized, the formation of voids or pipelines in trench-filled materials leads to reliability issues in semiconductor devices, such as increased gate leak current and contamination, due to the reduction in trench width and aspect ratio.
Innovation Solution
A method involving overfilling trenches with an undoped semiconductor material, followed by the deposition of a doped semiconductor material and a thermal treatment to diffuse the dopant, resulting in a doped semiconductor material with a decreasing concentration gradient, which prevents void or pipeline formation during heat treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the width of a trench is reduced to scale down semiconductor elements, then the miniaturization of semiconductor elements is achieved, but voids or pipelines are formed in the material filled in the trench, resulting in decreased reliability
Solution Approach 1:
The patent applies preliminary action by first forming a liner layer on the trench walls before filling the trench with semiconductor material. This liner layer is formed in advance to prevent void and pipeline formation during subsequent material deposition and thermal processing, thereby ensuring reliability even as trench dimensions are reduced for miniaturization
Solution Approach 2:
The patent employs parameter changes by controlling the deposition conditions and thermal processing parameters to achieve complete trench filling without voids. By optimizing deposition temperature, pressure, and thermal annealing conditions, the material fills the trench uniformly and maintains integrity during processing, resolving the reliability issue associated with reduced trench width
2Productivity
If the aspect ratio of a trench is increased to achieve miniaturization, then the density of interconnected elements per unit area is increased, but defects such as voids or pipelines are formed in the filled material, decreasing reliability
Solution Approach 1:
The liner layer is formed preliminarily on the trench walls before material filling, providing a nucleation surface that promotes uniform material deposition. This preliminary structure prevents void formation in high aspect ratio trenches, enabling increased element density without compromising reliability
Solution Approach 2:
The liner layer acts as an intermediary between the trench structure and the semiconductor material. It mediates the interaction by providing a controlled interface that facilitates complete material filling and prevents defect formation, even in high aspect ratio trenches required for increased element density
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 enhances the reliability of semiconductor devices by preventing contamination and reducing gate leak current, while maintaining the integrity of the doped semiconductor material within the trench, thereby improving the performance and reliability of semiconductor structures.
Implementation Method 1
performing a thermal treatment so that the dopant in the second semiconductor material diffuses into the first semiconductor material to form a doped third semiconductor material in the trench
Implementation Method 2
performing a thermal treatment so that the dopant in the second semiconductor material diffuses into the first semiconductor material
Data Source
AI summary
A method of fabricating a semiconductor structure includes providing a semiconductor substrate, forming a trench in the semiconductor substrate, overfilling the trench with a first semiconductor material, wherein the first semiconductor material does not have a dopant, forming a second semiconductor material on the first semiconductor material, wherein the second semiconductor material contains a dopant, and performing a thermal treatment so that the dopant in the second semiconductor material diffuses into the first semiconductor material to form a doped third semiconductor material in the trench.