Isolation Structure Fabrication for Flat Substrate Profile
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Solution Overview
Problem
The challenge in semiconductor device manufacturing is achieving a flat substrate profile when forming isolation structures with trenches of varying widths, which affects the uniformity of pattern density and subsequent manufacturing processes.
Innovation Solution
A method involving the sequential formation and patterning of multiple hard mask layers on a substrate, followed by the removal of specific layers to create trenches of different widths, ensuring a flat surface for uniform isolation material deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If trenches of different widths are formed in the substrate to achieve high density and integration, then the degree of integration is improved, but the pattern density becomes non-uniform causing height difference on the substrate surface
Solution Approach 1:
The patent divides the substrate surface into multiple regions with different pattern densities by forming trenches of different widths. Each region is independently patterned to achieve the desired integration density while managing the flatness challenge through subsequent fill processes.
Solution Approach 2:
The patent applies different trench widths and isolation fill heights to different regions of the substrate based on local pattern density requirements. This allows each region to be optimized for its specific integration needs while the overall substrate maintains manufacturability.
2Manufacturing precision
If multiple hard mask layers are sequentially formed and patterned to create trenches of different widths, then the flatness of the substrate surface is improved, but the manufacturing process complexity increases
Solution Approach 1:
The patent uses multiple hard mask layers where each layer is patterned within the context of the previous layers. The first, second, and third hard mask layers are sequentially formed and patterned, with each layer serving as a template for the next, creating a nested structure that enables precise trench width control.
Solution Approach 2:
The patent performs preliminary patterning actions by forming and patterning multiple hard mask layers before actually etching the trenches. This preliminary action establishes the precise width variations needed for different pattern density regions, ensuring that the subsequent trench formation and isolation fill processes can achieve the desired flat substrate surface.
Data Source
AI summary
A method of fabricating an isolation structure is provided. A first oxide layer and a first, second, and third hard mask layers are formed on a substrate. A patterned third hard mask layer is formed. Second oxide layers are formed on sidewalls of the patterned third hard mask layer and a fourth hard mask layer is formed between the second oxide layers. The second oxide layers and the second hard mask layer are removed using the patterned third hard mask layer and the fourth hard mask layer as a mask, to form a patterned second hard mask layer. The patterned third hard mask layer and the fourth hard mask layer are removed. A portion of the patterned second hard mask layer is removed to form trench patterns. A patterned first hard mask layer and first oxide layer, and trenches located in the substrate are defined. An isolation material is formed.