Shallow Trench Isolation Divot Prevention via Protective Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The shallow trench isolation (STI) manufacturing process faces issues with divots forming at the corner regions of the insulation layer due to etching during the removal of patterned layers, which can lead to short circuits in subsequent components and uneven substrate surface heights.
Innovation Solution
A method is introduced where a protection layer and an additional insulation layer are formed on the substrate before removing the patterned mask and pad layers, using silicon oxynitride and silicon oxide materials respectively, to prevent damage to the insulation layer and control the step height uniformity, employing wet etching processes to carefully remove these layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wet etching process is used to remove the patterned pad layer and mask layer, then the patterned layers are successfully removed, but the insulation layer in the trenches is etched causing divots to form at the corner regions
Solution Approach 1:
A protection layer is formed conformally on the substrate before removing the patterned layers. This protection layer is deposited in advance to cover and protect the insulation layer in the trenches from etching damage that will occur during subsequent removal of the patterned pad layer and mask layer.
Solution Approach 2:
The protection layer acts as an intermediary barrier between the etchant and the insulation layer. It is selectively etched after serving its protective function, allowing the patterned layers to be removed while preventing direct contact between the etchant and the insulation layer, thus avoiding divot formation.
2Ease of manufacture
If the patterned mask layer and pad layer are removed by wet etching, then the masking function is completed, but the substrate surface height becomes uneven due to insulation layer etching
Solution Approach 1:
The protection layer is deposited conformally on the substrate surface before the patterned layers are removed. This preliminary action ensures that when wet etching is performed to remove the patterned layers, the protection layer is present to prevent uneven etching of the insulation layer, thereby maintaining uniform substrate surface height.
Solution Approach 2:
The protection layer serves as a mediator that prevents the etchant from directly attacking the insulation layer during the removal of patterned layers. This intermediary protection ensures uniform etching and maintains the substrate surface uniformity required for subsequent manufacturing steps.
3Productivity
If divots are formed at the corner regions of the insulation layer, then the wet etching process is effective, but short circuits may occur in subsequently formed components
Solution Approach 1:
The protection layer is formed in advance before the wet etching process. This preliminary protective measure ensures that when the wet etching process is performed to remove patterned layers, the insulation layer is protected from etching that would create divots, thereby maintaining electrical isolation and preventing short circuits in subsequent components.
Solution Approach 2:
The protection layer acts as an intermediary barrier that prevents the etchant from reaching and damaging the insulation layer during the wet etching process. This protection maintains the integrity of the insulation layer, ensuring reliable electrical isolation between adjacent components.
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 effectively prevents divot formation at the corner regions of the STI structure, ensuring the insulation layer's integrity and improving the uniformity of the substrate surface, thereby reducing the risk of short circuits and enhancing the manufacturing process's reliability.
Implementation Method 1
a protection layer is conformally formed on the substrate
Implementation Method 2
a wet etching process is implemented to remove the residual insulation material layer on the patterned mask layer 104
Implementation Method 3
a second insulation layer is formed on the protection layer above the first insulation layer
Data Source
AI summary
A method for manufacturing a shallow trench isolation (STI) structure is provided. In the method, a substrate is initially provided. Then, a patterned pad layer and a patterned mask layer are successively formed in order on the substrate. After that, a portion of the substrate is removed by using the patterned mask layer and the patterned pad layer as a mask to form trenches in the substrate. Next, a first insulation layer is formed in the trenches. Afterwards, a protection layer is conformally formed on the substrate. Then, a second insulation layer is formed on the protection layer above the first insulation layer. Next, the patterned mask layer and the patterned pad layer are removed. Finally, a portion of the protection layer and the second insulation layer are removed.