Semiconductor Isolation Structure with Etch Protection Layer
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Solution Overview
Problem
Conventional semiconductor manufacturing methods result in the loss of isolation structures during cleaning processes, leading to decreased active region widths and increased resistance in semiconductor devices, as well as abnormal epi-silicon layer growth and bridge phenomena.
Innovation Solution
A method involving the formation of an etch protection layer between insulation layers within trenches, which prevents loss during cleaning and ensures the isolation structure remains higher than active regions, stabilizing epi-silicon layer growth by recessing active regions and using a stacked insulation layer structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional single-layer insulation structure is used for isolation, then the manufacturing process is simple, but the isolation structure is lost during cleaning processes leading to decreased active region width
Solution Approach 1:
The isolation structure is divided into multiple layers: a first insulation layer (oxide) and a second insulation layer (nitride). This segmented structure prevents loss during cleaning processes while maintaining manufacturing simplicity, as each layer serves a specific protective function.
Solution Approach 2:
The patent uses a composite insulation structure combining different materials (oxide and nitride layers) with distinct properties. The oxide layer provides good interface characteristics while the nitride layer provides erosion resistance during cleaning, achieving both ease of manufacture and manufacturing precision.
2Ease of operation
If the isolation structure height is reduced to match active regions, then cleaning processes can proceed, but the moat phenomenon occurs causing active region oxidation and width decrease
Solution Approach 1:
The etch protection layer is formed preliminarily before the cleaning process to protect the isolation structure. This preliminary protective action allows the cleaning process to proceed without causing the moat phenomenon or active region oxidation.
Solution Approach 2:
The multi-layer insulation structure acts as a cushion against the harmful cleaning process. The nitride layer specifically cushions against erosion, preventing the isolation structure loss that would otherwise lead to the moat phenomenon and active region oxidation.
3Productivity
If active regions have narrow width, then device integration is high, but epi-silicon layers form abnormally and bridge phenomena occur
Solution Approach 1:
The patent applies different material properties at different locations: the oxide layer provides good interface quality at the silicon-insulation interface, while the nitride layer provides protective quality at the exposed surfaces during cleaning. This local quality differentiation ensures reliable epi-silicon formation even with narrow active regions.
Data Source
AI summary
A method for manufacturing a semiconductor device that can prevent the loss of an isolation structure and that can also stably form epi-silicon layers is described. The method for manufacturing a semiconductor device includes defining trenches in a semiconductor substrate having active regions and isolation regions. The trenches are partially filled with a first insulation layer. An etch protection layer is formed on the surfaces of the trenches that are filled with the first insulation layer. A second insulation layer is filled in the trenches formed with the etch protection layer to form an isolation structure in the isolation regions of the semiconductor substrate. Finally, portions of the active regions of the semiconductor substrate are recessed such that the isolation structure has a height higher than the active regions of the semiconductor substrate.