Tungsten Bottom Electrode Via CMP Selectivity
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Solution Overview
Problem
Chemical mechanical polishing (CMP) in semiconductor manufacturing can damage raised metal interconnection lines due to low polish selectivity between the bottom electrode layer and the polish stop layer, leading to overpolishing and exposure of metal lines in logic and memory regions.
Innovation Solution
Employing tungsten as the bottom electrode via (BEVA) embedded in a polish stop structure with high selectivity, such as silicon-rich oxide or silicon carbide, to resist CMP and prevent damage, while utilizing a high-selectivity slurry to stop the polishing process effectively, ensuring a void-free and dimple-free surface for subsequent layer formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If chemical mechanical polishing (CMP) is used to planarize the bottom electrode layer, then a flat surface is achieved for subsequent layers, but raised metal interconnection lines are damaged due to low polish selectivity
Solution Approach 1:
A polish stop layer is introduced as an intermediary between the bottom electrode layer and the metal interconnection lines. This stop layer has high CMP selectivity, allowing the CMP process to planarize the bottom electrode layer while automatically stopping before damaging the raised metal lines, thus protecting them from over-polishing damage
Solution Approach 2:
The invention changes the material composition and polishing resistance parameters of the structure by introducing a polish stop layer with specific properties (high CMP resistance). This parameter change enables differential polishing rates, allowing selective removal of the bottom electrode layer while preserving the metal interconnection lines
2Object-affected harmful factors
If tungsten is used as bottom electrode via (BEVA) with high polish selectivity, then damage to raised metal interconnection lines is prevented, but the process complexity increases
Solution Approach 1:
Tungsten BEVA structures are formed as intermediaries within the polish stop layer. The tungsten provides high CMP selectivity, acting as a mediator that enables the CMP process to stop precisely at the desired location, preventing damage to metal lines while maintaining process control
Solution Approach 2:
The invention uses composite material structures combining tungsten BEVA within the polish stop layer. This composite approach leverages the high CMP selectivity of tungsten to create a multi-functional structure that both protects metal lines and provides precise process control
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 use of tungsten BEVA with high polish selectivity mitigates damage to raised metal interconnection lines and provides a flat surface for subsequent layers, enhancing the integration and reliability of memory devices by preventing voids and dimples, thus improving the manufacturing process.
Implementation Method 1
Chemical mechanical polishing (CMP) in semiconductor manufacturing can damage raised metal interconnection lines due to low polish selectivity between the bottom electrode layer and the polish stop layer
Implementation Method 2
polishing a top surface of the tungsten layer until reaching the polish stop structure
Data Source
AI summary
A memory device includes a dielectric structure, a tungsten plug, a bottom electrode, a resistance switching element and a top electrode. The dielectric structure has an opening. The tungsten plug is embedded in the opening of the dielectric structure. The bottom electrode extends along top surfaces of the dielectric structure and the tungsten plug. The resistance switching element is present over the bottom electrode. The top electrode is present over the resistance switching element.