Boron-Doped Silicon Hard Mask for Fine Pattern Etching
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Solution Overview
Problem
The limited resolution of exposure systems in semiconductor devices makes it difficult to pattern narrow lines effectively using photoresist alone, necessitating the development of a hard mask with high etch selectivity and ease of stripping.
Innovation Solution
A semiconductor device is fabricated using a hard mask layer comprising a first boron-doped silicon layer with a graded boron concentration and a second boron-doped silicon layer with a higher boron concentration, which acts as an etch barrier to achieve vertical etch profiles and improve processing stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photoresist alone is used for patterning, then the process is simple, but the resolution is insufficient for narrow lines
Solution Approach 1:
The hard mask layer is divided into multiple sub-layers with different boron concentrations. The first sub-layer has a lower boron concentration for easier stripping, while the second sub-layer has a higher boron concentration for maintaining pattern fidelity during etching. This segmentation allows the system to achieve high resolution patterning while managing the complexity through functional division.
Solution Approach 2:
The hard mask layer uses a composite structure combining silicon and boron in varying concentrations. This composite material approach enables the hard mask to simultaneously provide high etch selectivity (for precision) and controlled removability (for process management), resolving the contradiction between achieving narrow line patterns and maintaining process simplicity.
2Manufacturing precision
If a hard mask with high etch selectivity is used, then etching precision is improved, but the hard mask becomes difficult to strip
Solution Approach 1:
The hard mask layer is segmented into functional sub-layers: the first sub-layer with lower boron concentration serves as the stripping-sensitive layer, while the second sub-layer with higher boron concentration serves as the etch-resistant layer. This segmentation enables differential etching where the first layer can be selectively removed after serving its patterning function, resolving the contradiction between etch selectivity and stripping ease.
Solution Approach 2:
Different regions of the hard mask layer are assigned different boron concentrations to fulfill different functions. The lower boron concentration region (first sub-layer) provides ease of stripping, while the higher boron concentration region (second sub-layer) provides etch selectivity. This local quality differentiation allows the single hard mask structure to simultaneously satisfy both contradictory requirements.
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 high etch selectivity and ease of stripping of the boron-doped silicon layers enable precise etching and enhance the reliability of semiconductor device fabrication by forming vertically oriented etch profiles.
Implementation Method 1
a hard mask layer comprising a first boron-doped silicon layer with a graded boron concentration and a second boron-doped silicon layer with a higher boron concentration, which acts as an etch barrier
Implementation Method 2
the hard mask layer including a first boron-doped silicon layer and a second boron-doped silicon layer on the first boron-doped silicon layer, wherein the second boron-doped silicon layer has a larger boron concentration than the first boron-doped silicon layer
Data Source
AI summary
The technology relates to a semiconductor device including a hard mask easy to strip and capable of implementing a fine pattern with a high etch selectivity. According to an embodiment of the disclosure, a method for fabricating a semiconductor device comprises forming an etching target layer, forming a hard mask layer on the etching target layer, the hard mask layer including a first boron-doped silicon layer and a second boron-doped silicon layer on the first boron-doped silicon layer, and etching the etching target layer using the hard mask layer as an etching barrier, wherein the second boron-doped silicon layer has a larger boron concentration than the first boron-doped silicon layer.