Bottom-Up SiGe Micro-Feature Filling via Seed Layer Transfer
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Solution Overview
Problem
Conventional silicon (Si) and silicon germanium (SiGe) fill processes for micro-features in semiconductor devices often result in voids and defects, especially in complex shapes and retrograde wall profiles, leading to electrical resistance issues and circuit operation problems.
Innovation Solution
A method involving the formation of a Si or SiGe seed layer at the bottom of micro-features, followed by selective growth from the bottom up, using heat treatment and etching to transfer material from sidewalls to the bottom, ensuring uniform filling and minimizing voids, particularly effective for retrograde and vertical walled micro-features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conformal Si deposition is used to fill micro-features, then the filling process is simple and straightforward, but voids and defects are created inside the micro-features
Solution Approach 1:
A seed layer is deposited at the bottom of the micro-features before the main fill process. This preliminary action creates a foundation that enables subsequent selective growth from the bottom up, preventing void formation while maintaining process feasibility
Solution Approach 2:
Instead of filling from the top down or using conformal deposition that closes openings prematurely, the invention inverts the approach by initiating growth from the bottom of the micro-features upward. This reversal allows continuous opening access and prevents void formation
2Ease of manufacture
If conformal Si deposition is used for filling, then the process is easy to implement, but seams are created in the fill
Solution Approach 1:
The seed layer is deposited in advance at the bottom surface, creating a uniform foundation that guides subsequent growth. This preliminary action ensures uniform material distribution and prevents seam formation during the fill process
Solution Approach 2:
The seed layer provides localized quality enhancement at the bottom of micro-features, creating a specific growth initiation zone that ensures uniform upward growth and eliminates seams in the final fill structure
3Ease of manufacture
If conventional fill processes are used, then the process is simple, but voids are created in retrograde wall micro-features
Solution Approach 1:
The seed layer is deposited at the bottom of retrograde wall micro-features before filling. This preliminary action ensures that growth initiates from the bottom upward, navigating the complex retrograde geometry without creating voids while maintaining process simplicity
Solution Approach 2:
The invention inverts the conventional approach by growing from the bottom up rather than top down or conformally. This reversal is particularly effective for retrograde wall micro-features, ensuring complete filling without voids
4Ease of manufacture
If conformal deposition is used, then the process is straightforward, but the aspect ratio of filled features increases
Solution Approach 1:
The seed layer deposited at the bottom provides a foundation that enables controlled upward growth. This preliminary action allows for more efficient filling that reduces the final height of filled material, thereby reducing the aspect ratio compared to conformal deposition
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 provides reduced or void-free filling of complex micro-feature shapes with minimal overfilling, enhancing the reliability and performance of semiconductor devices by reducing defects and aspect ratio, and allowing for capping with different materials to reduce cross-talk.
Implementation Method 1
heat treating the Si or SiGe layer in the presence of H2 gas to transfer at least a portion of the Si or SiGe layer from the sidewall to the bottom of the micro-feature
Implementation Method 2
at least partially filling the micro-feature from the bottom up by selectively growing Si or SiGe onto the Si or SiGe seed layer
Data Source
AI summary
A method is provided for reduced defect such as void free or reduced void Si or SiGe deposition in a micro-feature on a patterned substrate. The micro-feature includes a sidewall and the patterned substrate contains an isolation layer on the field area and on the sidewall and bottom of the micro-feature. The method includes forming a Si or SiGe seed layer at the bottom of the micro-feature, and at least partially filling the micro-feature from the bottom up by selectively growing Si or SiGe onto the Si or SiGe seed layer. According to one embodiment, the Si or SiGe seed layer is formed by depositing a conformal Si or SiGe layer onto the patterned substrate, removing the Si or SiGe layer from the field area, heat treating the Si or SiGe layer in the presence of H2 gas to transfer at least a portion of the Si or SiGe layer from the sidewall to the bottom of the micro-feature, and etching Si or SiGe residue from the field area and the sidewall.