Silicon Oxygen Metal Gate Buffer Layer Interface Reliability
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Solution Overview
Problem
Conventional poly-silicon gates in semiconductor devices face performance issues due to boron penetration and depletion effects, leading to reduced gate capacitance and driving force, necessitating the replacement with metal gates, but the planarization process can introduce defects and reliability concerns at the interface between metal gates and dielectric layers.
Innovation Solution
A silicon and oxygen-containing metal layer is formed between the metal gate and the dielectric layer through a deposition process, which acts as a buffer to improve microstructures and reduce defects, enhancing electrical reliability by smoothing the interface and reducing dislocations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal gate is formed by planarization process, then the gate electrode can replace poly-silicon gate, but defects and reliability issues occur at the interface between metal gate and dielectric layer
Solution Approach 1:
A silicon-containing metal layer is introduced as an intermediary layer between the metal gate and the dielectric layer. This intermediate layer acts as a buffer that reduces interface defects and improves the reliability of the metal gate-dielectric interface, eliminating the need for additional oxidizing steps.
Solution Approach 2:
The invention changes the material composition parameter by introducing a silicon-containing metal layer with specific silicon concentration. This parameter change transforms the interface properties, reducing defects and improving reliability without requiring additional processing steps.
2Device complexity
If conventional poly-silicon gate is used, then the gate structure is simple, but boron penetration and depletion effects reduce gate capacitance and driving force
Solution Approach 1:
The gate structure uses composite materials by combining metal layers with silicon-containing metal layers. This composite structure maintains relative simplicity while improving gate performance by eliminating boron penetration and depletion effects that plague conventional poly-silicon gates.
3Manufacturing precision
If additional oxidizing steps are performed to form silicon-containing metal layer, then interface quality improves, but processing time and costs increase
Solution Approach 1:
The formation of the silicon-containing metal layer is merged with the existing metal gate formation process. By combining these steps into a single deposition process, the invention achieves high interface quality without requiring additional oxidizing steps, thereby reducing processing time and costs.
Solution Approach 2:
The silicon-containing metal layer is formed preliminarily during the metal gate deposition process itself, before subsequent dielectric layer formation. This preliminary action ensures high interface quality is built-in from the start, eliminating the need for later oxidizing steps.
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 silicon and oxygen-containing metal layer effectively buffers the metal gate and dielectric layer interface, improving microstructures and electrical performance by reducing defects and enhancing reliability, while also simplifying the process by eliminating the need for additional oxidizing steps and reducing processing time and costs.
Implementation Method 1
A silicon-containing deposition process is performed to import silicon atoms into a top surface of the metal gate, thereby forming a silicon-containing metal layer on the metal gate
Implementation Method 2
A silicon and oxygen-containing deposition process is performed to form a second dielectric layer on the silicon-containing metal layer and the first dielectric layer
Data Source
AI summary
A metal gate process for polishing and oxidizing includes the following steps. A first dielectric layer having a trench is formed on a substrate. A barrier layer and a metal layer are formed sequentially to cover the trench and the first dielectric layer. A first chemical mechanical polishing process including a slurry of H2O2 with the concentration of 0˜0.5 weight percent (wt. %) is performed to polish the metal layer until the barrier layer on the first dielectric layer is exposed. A second chemical mechanical polishing process including a slurry of H2O2 with the concentration higher than 1 weight percent (wt. %) is performed to polish the barrier layer as well as oxidize a surface of the metal layer remaining in the trench until the first dielectric layer is exposed, thereby a metal oxide layer being formed on the metal layer.