Hard Mask Layer Controls Recess Width in Semiconductor Etching
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Solution Overview
Problem
In semiconductor manufacturing, the etching process across multilayer structures with different material etching rates can lead to over-etching issues, particularly affecting the transfer of patterns and potentially causing short circuits due to uneven recess widths in dielectric layers.
Innovation Solution
A method involving the formation of a multilayer structure with a hard mask layer on the sidewalls of specific layers, where the hard mask layer has a controlled thickness to compensate for over-etching, and adjusting etching parameters to control recess widths and prevent excessive etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a standard etching process is used on multilayer structures with different materials, then the etching process is simple and fast, but over-etching occurs due to different etching rates of materials
Solution Approach 1:
A hard mask layer is formed in advance on the sidewall of the layer above the specific layer before the etching process. This preliminary action creates a protective barrier that compensates for the over-etching that would otherwise occur, allowing the etching process to proceed at normal speed while maintaining precision.
Solution Approach 2:
The hard mask layer acts as an intermediary protective layer between the etching environment and the dielectric layer. It mediates the etching process by providing a controlled barrier that prevents excessive etching of the underlying dielectric layer while allowing the etching to proceed efficiently.
2Device complexity
If no hard mask layer is used, then the process is simple, but the width of recesses varies due to over-etching
Solution Approach 1:
The hard mask layer is formed as a preliminary protective structure before the etching process begins. This advance preparation ensures that the recess width remains uniform by preventing over-etching, while adding only one additional process step to the overall fabrication sequence.
3Productivity
If the etching rate of a specific layer is increased to improve productivity, then etching is faster, but over-etching of underlying layers occurs
Solution Approach 1:
The hard mask layer serves as a cushioning protective layer that is positioned beforehand on the sidewall of the layer above the specific layer. This cushioning effect absorbs and compensates for the over-etching that occurs when high etching rates are used, preventing damage to the underlying dielectric layer while maintaining high productivity.
Solution Approach 2:
The hard mask layer acts as an intermediary barrier that allows high etching rates to be used without causing over-etching damage. It mediates between the aggressive etching process and the underlying layers, enabling fast etching while protecting against harmful over-etching effects.
Data Source
AI summary
The present invention provides a method for fabricating a semiconductor structure. A multilayer structure on is formed a substrate, the multilayer structure includes at least a first dielectric layer, a second dielectric layer and an amorphous silicon layer, next, a first etching step is performed, to forma first recess in the amorphous silicon layer and in the second dielectric layer, parts of the first dielectric layer is exposed by the first recess, afterwards, a hard mask layer is formed in the first recess, a second etching step is then performed to remove the hard mask layer and to expose a surface of the first dielectric layer, and a third etching step is performed with the remaining hard mask layer, to remove a portion of the first dielectric layer, so as to form a second recess in the first dielectric layer.