Stop Layer Modification for Etching Selectivity
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Solution Overview
Problem
The existing IC manufacturing process faces challenges in maintaining accuracy and control as feature sizes decrease, leading to potential short circuits and leakage due to lateral etching of the stop layer during the formation of second openings, which degrades semiconductor structure performance.
Innovation Solution
A method is introduced where a modification layer with a higher etching selectivity ratio is formed at the bottom of the first opening, using materials like aluminum or silicon oxide, which reduces damage to the stop layer during the etching process, thereby minimizing short circuits and leakage when forming second openings for conductive plugs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If direct etching is performed to form second openings without modifying the stop layer, then the etching process is simple and fast, but the stop layer sidewalls are damaged causing short circuits and leakage
Solution Approach 1:
The stop layer is modified in advance before the etching process to form a modification layer with different etching characteristics. This preliminary modification prevents sidewall damage during subsequent etching operations while maintaining high etching efficiency for forming second openings
Solution Approach 2:
A modification layer is introduced as an intermediary between the stop layer and the etching process. This intermediate layer protects the stop layer sidewalls from direct etching damage while allowing the etching process to proceed efficiently to form the second openings
2Reliability
If the stop layer is modified to form a modification layer, then sidewall damage is reduced and reliability is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The etching selectivity parameters are optimized to ensure the modification layer can be selectively removed without damaging the stop layer sidewalls. By adjusting etching chemistry and parameters, the additional process step becomes more efficient and integrates better with existing manufacturing flows
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
This approach limits damage to the stop layer sidewalls, preventing short circuits and improving the overall performance of the semiconductor structure by ensuring precise etching and accurate formation of conductive plugs.
Implementation Method 1
a plasma processing process is performed to modify the portion of the stop layer exposed at the bottom of the first opening
Implementation Method 2
the modification layer is removed by a wet etching process, and an etching solution used in the wet etching process includes a hydroxylamine solution or a hydrogen fluoride solution
Data Source
AI summary
A method for forming a semiconductor structure includes providing a substrate, forming a stop layer over a surface of the substrate, forming a dielectric layer over a surface of the stop layer, forming a first opening in the dielectric layer and exposing a portion of the stop layer, modifying the portion of the stop layer exposed at a bottom of the first opening to form a modification layer, and removing the modification layer to form a second opening from the first opening.