Boron-Doped Silicon Hard Mask for Fine-Pattern Etch Control
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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 use of a hard mask with high etch selectivity.
Innovation Solution
A semiconductor device is fabricated using a hard mask layer composed of 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 enhance etch selectivity and facilitate easy stripping.
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 (first boron-doped silicon layer and second boron-doped silicon layer). This segmentation allows each sub-layer to serve different functions: the lower concentration layer provides etch selectivity while the higher concentration layer facilitates easy stripping, thereby achieving high-resolution patterning without excessive process complexity
Solution Approach 2:
The patent uses a composite hard mask structure combining silicon layers doped with different boron concentrations. This composite material approach enables the hard mask to simultaneously exhibit high etch selectivity relative to the mandrel layer and ease of stripping, 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 patterning precision is improved, but the hard mask becomes difficult to strip
Solution Approach 1:
Different regions of the hard mask layer are assigned different boron concentrations to achieve different local properties. The first boron-doped silicon layer (lower concentration) provides high etch selectivity for precise etch profile control, while the second boron-doped silicon layer (higher concentration) is specifically designed for easy stripping, thus resolving the contradiction between etch precision and stripping ease
Solution Approach 2:
The hard mask is segmented into functional zones with distinct boron doping levels. This segmentation enables the lower layer to interact selectively with the mandrel during etching while the upper layer remains accessible to stripping chemicals, achieving both precise etch profile control and easy removal
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, easy-to-strip hard mask layer allows for the formation of a vertically controlled etch profile, improving processing stability and reliability in semiconductor devices.
Implementation Method 1
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
Implementation Method 2
a first boron-doped silicon layer having a graded concentration of boron and a second boron-doped silicon layer having a non-graded concentration of boron
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.