Semiconductor Trench Filling with Two-Step Deposition and V-Etch
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Solution Overview
Problem
Current semiconductor processes face challenges in forming high aspect ratio openings due to inadequate step coverage during deposition, leading to voids and poor device performance.
Innovation Solution
A two-stepped deposition process is employed, followed by v-shaped etching to expose voids, allowing a second semiconductor layer to fill the openings effectively, thereby improving void issues and enhancing device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single deposition process is used to fill high aspect ratio openings, then the process is simple and fast, but voids form due to inadequate step coverage
Solution Approach 1:
The deposition process is divided into multiple sequential steps: first deposition to form initial semiconductor layer, selective removal to create V-shaped profile, and second deposition to complete filling. This segmentation allows each step to optimize for its specific function, eliminating voids while maintaining manageable process complexity through modular operations.
Solution Approach 2:
The first deposition and selective removal create a preliminary V-shaped profile that prepares the opening for optimal second deposition. This preliminary action modifies the geometry to enable complete filling in the subsequent step, ensuring no voids form during the final deposition while keeping the overall process structured and controllable.
2Reliability
If conventional deposition is used in high aspect ratio openings, then the process is straightforward, but voids form at the bottom of openings
Solution Approach 1:
The selective removal process creates a V-shaped (curved) profile at the bottom of the opening instead of a straight vertical wall. This curvature allows deposition material to follow the angled surfaces and reach the bottom uniformly, eliminating void formation and ensuring reliable device performance while maintaining good deposition uniformity throughout the opening.
3Manufacturing precision
If the opening has vertical sidewalls, then the etching process is simple, but deposition coverage is poor and voids form
Solution Approach 1:
The etching process creates an asymmetric V-shaped profile with different angles on each side of the opening, rather than symmetric vertical walls. This asymmetry in geometry is specifically designed to improve deposition step coverage, allowing material to deposit uniformly along the angled surfaces and reach the bottom, while the etching complexity remains manageable through standard anisotropic etching techniques.
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 effectively addresses void formation in high aspect ratio openings, resulting in improved semiconductor device performance and practical application in semiconductor memory devices like DRAM.
Implementation Method 1
a first deposition process is performed to form a first semiconductor layer to fill up the opening and to cover a top surface of the dielectric layer
Implementation Method 2
a removing process is performed to laterally etch the first semiconductor layer till exposing the transition portion of the opening
Data Source
AI summary
A method of forming a semiconductor device includes the following steps. First of all, a substrate is provided, and a dielectric layer is formed on the substrate. Then, at least one trench is formed in the dielectric layer, to partially expose a top surface of the substrate. The trench includes a discontinuous sidewall having a turning portion. Next, a first deposition process is performed, to deposit a first semiconductor layer to fill up the trench and to further cover on the top surface of the dielectric layer. Following these, the first semiconductor layer is laterally etched, to partially remove the first semiconductor layer till exposing the turning portion of the trench. Finally, a second deposition is performed, to deposit a second semiconductor layer to fill up the trench.