Wet Etching Process for Semiconductor Substrate Doping Oxide Layer
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Solution Overview
Problem
Dry etching processes can damage semiconductor substrates, while wet etching processes often cause lateral etching of the doping oxide layer beyond the patterning layer sidewalls, compromising precision in semiconductor fabrication.
Innovation Solution
An improved wet etching process is implemented, which includes a soft sputtering step to weaken the doping oxide layer before wet etching, reducing the time for the wet etching process and using a protective layer to minimize lateral etching, thereby protecting the substrate and maintaining precise patterning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a dry etching process is used to remove the doping oxide layer, then the etching speed is fast and the process is efficient, but the underlying substrate is damaged
Solution Approach 1:
The patent replaces the mechanical/physical sputtering process with a chemical wet etching process using HF-based solutions. This substitution allows the doping oxide layer to be removed through chemical dissolution rather than physical bombardment, thereby avoiding substrate damage while maintaining effective removal capability.
Solution Approach 2:
The patent modifies the chemical composition parameters of the etching solution by using HF-based solutions with specific additives. This parameter change enables selective etching of the doping oxide layer while protecting the substrate, resolving the contradiction between etching efficiency and substrate protection.
2Object-affected harmful factors
If a wet etching process is used to remove the doping oxide layer, then the substrate is protected from damage, but lateral etching occurs beyond the sidewalls of the patterning layer
Solution Approach 1:
The patent introduces a protective layer as an intermediary between the patterning layer and the doping oxide layer. This protective layer prevents the wet etchant from accessing and laterally etching the doping oxide beyond the patterned regions, thereby maintaining manufacturing precision while allowing safe use of wet etching.
Solution Approach 2:
The protective layer is applied in advance before the wet etching process to preemptively block the etchant from causing lateral etching. This preliminary protective action prevents the harmful lateral etching effect before it can occur, resolving the precision issue.
3Reliability
If the wet etching process time is extended to ensure complete removal of the doping oxide layer, then the etching is thorough, but lateral etching beyond the patterning layer sidewalls increases
Solution Approach 1:
The protective layer serves as a mediator that enables extended etching time for complete removal of the doping oxide layer without increasing lateral etching. By blocking the etchant path, it allows the etching process to proceed thoroughly in the vertical direction while preventing lateral spread.
Solution Approach 2:
The patent segments the etching process into two distinct stages: first, protective layer removal exposing the doping oxide; second, controlled wet etching of the doping oxide with the protective layer still in place on sidewalls. This segmentation allows thorough etching without lateral over-etching.
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 method effectively reduces lateral etching of the doping oxide layer beyond the patterning layer sidewalls, ensuring more precise doping and minimizing damage to the semiconductor substrate, thus enhancing the accuracy of semiconductor fabrication processes.
Implementation Method 1
performing a sputtering process to the substrate
Implementation Method 2
performing a wet etching process to the semiconductor substrate to remove the doping oxide layer from the exposed regions
Data Source
AI summary
A method includes providing a semiconductor substrate; forming a doping oxide layer on the semiconductor substrate; forming a patterning layer on the doping oxide layer, the patterning layer leaving exposed regions of the doping oxide layer; performing a sputtering process to the substrate; and after the sputtering process, performing a wet etching process to the semiconductor substrate to remove the doping oxide layer from the exposed regions.