Semiconductor Contact Plug Doping Profile for Void-Free Trench Fill
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Solution Overview
Problem
The reduction in critical dimension of semiconductor structures poses challenges in achieving high yield and performance due to increased requirements for void reduction and seam size in contact plugs.
Innovation Solution
A manufacturing method involving the deposition of a first contact layer with high doping concentration, a second contact layer with lower doping concentration, and an annealing process to diffuse dopants, resulting in a contact plug with reduced seam size and voids by forming a uniform doping concentration across layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a single contact layer with high doping concentration is deposited to fill the trench, then the contact plug achieves sufficient doping concentration for electrical connection, but the surface roughness increases and voids form during deposition
Solution Approach 1:
The contact layer is divided into multiple sub-layers with different doping concentrations. The first contact layer has high doping concentration to provide sufficient dopant supply, while the second contact layer has lower doping concentration to achieve smooth surface and fill voids. This segmentation resolves the contradiction between achieving high doping concentration and maintaining surface quality.
Solution Approach 2:
The doping concentration parameter is changed across different layers of the contact plug. The first contact layer uses high doping concentration (e.g., 1E19 to 1E21 atoms/cm³) while the second contact layer uses lower doping concentration (e.g., 1E17 to 1E19 atoms/cm³). This parameter variation allows each layer to perform its specific function optimally.
2Volume of moving object
If the critical dimension of the semiconductor structure is reduced to achieve smaller size and higher integration, then the electronic product becomes more compact, but the requirement for fewer voids in the structure becomes more stringent
Solution Approach 1:
The second contact layer with lower doping concentration is deposited preliminarily to ensure smooth surface formation and void-free filling before final doping activation. This preliminary action with controlled deposition parameters prevents void formation that would be more critical in smaller structures.
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 reduces seam size and voids in the contact plug, enhancing the yield and performance of semiconductor structures by ensuring uniform doping concentration and smooth surface roughness.
Implementation Method 1
An annealing process is performed on the first contact layer and the second contact layer, such that dopants in the first contact layer diffuse into the second contact layer
Implementation Method 2
dopants in the first contact layer diffuse into the second contact layer
Data Source
AI summary
The present disclosure provides a manufacturing method of a semiconductor structure including the following steps. A trench is formed between bit lines. A seed layer is deposited in the trench, and a first contact layer is deposited on the seed layer in the trench. A second contact layer is deposited on the first contact layer to fill the trench, in which a second doping concentration of the second contact layer is lower than a first doping concentration of the first contact layer. An annealing process is performed on the first contact layer and the second contact layer, such that dopants in the first contact layer diffuse into the second contact layer to form a contact plug including the first contact layer and the second contact layer.