Semiconductor Contact Features With Bottom-Up Fill to Prevent Voids
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Solution Overview
Problem
The semiconductor industry faces challenges in achieving low-resistance contact features with minimal seam or void formation, while maintaining high yield and grain size, during the manufacturing of FinFET devices.
Innovation Solution
The method involves performing surface modification and etch processes on the sidewalls of contact openings to remove barrier/adhesion layers, followed by selective bottom-up deposition of contact features, which reduces selectivity loss and enables low-resistance contacts with improved grain size and yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional contact feature formation methods are used, then contact features can be formed, but seam and void formation occurs leading to high resistance and low yield
Solution Approach 1:
A liner layer is formed on the sidewalls of contact openings before depositing the contact feature material. This preliminary action provides a controlled surface that prevents seam and void formation during subsequent material deposition, ensuring high-quality contact features without defects.
Solution Approach 2:
The liner layer acts as an intermediary between the contact opening sidewalls and the contact feature material. This intermediate layer facilitates uniform material deposition and prevents direct contact between the material and sidewalls that would cause seams and voids, thereby improving contact feature quality.
2Reliability
If barrier/adhesion layers are not removed from sidewalls, then deposition process is simpler, but selectivity loss occurs preventing low-resistance contacts
Solution Approach 1:
Barrier and adhesion layers are selectively removed from the sidewalls of contact openings through etch processes. This extraction of unwanted layers from specific locations enables selective deposition of contact feature material with high selectivity, achieving low-resistance contacts while managing process complexity through targeted removal.
Solution Approach 2:
The sidewalls of contact openings are selectively treated by removing barrier/adhesion layers only in specific locations where contact features will be deposited. This local modification creates different surface properties in different areas, enabling high-selectivity deposition that achieves low contact resistance without requiring complete removal of layers throughout the entire structure.
3Productivity
If contact features are deposited without surface modification, then process is faster, but grain size is reduced and yield decreases
Solution Approach 1:
Surface modification processes are performed on the sidewalls of contact openings before depositing contact features. This preliminary preparation of the deposition surface promotes proper nucleation and growth of contact feature material, resulting in larger grain sizes and higher yield while maintaining acceptable deposition speeds through optimized process sequencing.
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 allows for the selective bottom-up deposition of contact features, reducing seam and void formation, and enhancing the grain size and yield of FinFET devices, thereby addressing the challenges of achieving low-resistance contacts.
Implementation Method 1
performing surface modification and etch processes on the sidewalls of contact openings to remove barrier/adhesion layers
Implementation Method 2
selective bottom-up deposition of contact features
Data Source
AI summary
A method includes forming a dielectric layer over an epitaxial source/drain region. An opening is formed in the dielectric layer. The opening exposes a portion of the epitaxial source/drain region. A barrier layer is formed on a sidewall and a bottom of the opening. An oxidation process is performing on the sidewall and the bottom of the opening. The oxidation process transforms a portion of the barrier layer into an oxidized barrier layer and transforms a portion of the dielectric layer adjacent to the oxidized barrier layer into a liner layer. The oxidized barrier layer is removed. The opening is filled with a conductive material in a bottom-up manner. The conductive material is in physical contact with the liner layer.