DRAM Capacitor Protective Layer for Bottom Electrode Integrity
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Solution Overview
Problem
The existing methods for forming capacitors in DRAMs often result in oxidation and deformation of the bottom electrode, leading to reliability issues and decreased performance due to the exposure of the bottom electrode during etching processes.
Innovation Solution
A method involving the formation of a protective layer to shield the bottom electrode during the removal of sacrificial layers, using a dielectric material like silicon oxide to prevent oxidation and deformation, and a structured sequence of etching and layer deposition to enhance capacitor integration and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the bottom electrode is exposed during etching processes to remove sacrificial layers, then the etching can be completed efficiently, but the bottom electrode surface suffers oxidation and deformation
Solution Approach 1:
A protective layer is introduced as an intermediary between the bottom electrode and the etching environment. This protective layer acts as a mediator that allows the etching process to proceed while preventing direct contact between the etching solution and the bottom electrode surface, thus avoiding oxidation and deformation.
Solution Approach 2:
The protective layer is formed on the bottom electrode surface before the etching process begins. This preliminary protective action ensures that when the sacrificial layers are subsequently removed through etching, the bottom electrode is already shielded and will not suffer from oxidation or deformation during the etching operations.
2Reliability
If a protective layer is added to shield the bottom electrode during etching, then the bottom electrode integrity is maintained, but the process complexity increases
Solution Approach 1:
The protective layer formation step is merged with the existing process flow by utilizing the same deposition equipment and materials already present in the manufacturing line. The protective layer is formed using silicon oxide deposition, which is a standard process step, thereby minimizing the addition of truly new process complexity while achieving the protective function.
3Ease of manufacture
If the protective layer is removed after etching, then the bottom electrode is fully exposed for subsequent steps, but the protective layer itself must be selectively removed without damaging the bottom electrode
Solution Approach 1:
The protective layer is designed with spatially varying properties - it covers the bottom electrode surface uniformly during etching but is positioned such that it can be selectively removed in specific areas afterward. The selective removal process targets only the protective layer while leaving the bottom electrode intact, achieving both full exposure when needed and precise protection when required.
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 protective layer effectively reduces surface damage and deformation of the bottom electrode, improving the reliability and performance of the capacitors by preventing oxidation and maintaining structural integrity during the etching process.
Implementation Method 1
the bottom electrode layer is protected by the protective layer; the sacrificial layer is removed, during which the bottom electrode layer is protected by the protective layer
Data Source
AI summary
A method for forming a capacitor includes: providing a substrate with an electric contact portion; forming a supporting layer and a sacrificial layer which are alternately laminated on a surface of the substrate, wherein the topmost layer is a supporting layer; forming a capacitor hole penetrating through the supporting layer and the sacrificial layer and exposing the electric contact portion; forming a bottom electrode layer covering an inner surface of the capacitor hole; forming a protective layer covering a surface of the bottom electrode layer; removing the sacrificial layer, during which the bottom electrode layer being protected by the protective layer; removing the protective layer; and sequentially forming a capacitor dielectric layer and a top electrode layer.