Middle-Layer HF Etching with Inhibitors for Spacer Preservation
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Solution Overview
Problem
In semiconductor manufacturing, the reduction of minimum feature sizes leads to increased challenges in etching processes, particularly due to the undesirable reaction of hydrofluoric acid with spacer materials during the removal of middle layers, resulting in topographical variations and cut fail defects, which affect processing quality and yield.
Innovation Solution
Incorporating an inhibitor, such as an N-ethanolamide derivative ligand, into the liquid etching solution to reduce the etch rate of spacer materials like titanium oxide, thereby minimizing damage during the removal of middle layers and reducing aspect ratios of openings, facilitating subsequent deposition processes without void formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If hydrofluoric acid is used to remove middle layers, then the middle layer is effectively removed, but the spacer material is damaged and topographical variations occur
Solution Approach 1:
The patent introduces an inhibitor as an intermediary substance that mediates between the hydrofluoric acid etchant and the spacer material. The inhibitor selectively binds to the spacer material surface, preventing direct contact and harmful reaction between the hydrofluoric acid and the spacer, thereby protecting the spacer while allowing middle layer removal
Solution Approach 2:
The patent converts the harmful reactive nature of hydrofluoric acid into a beneficial selective etching process. By using the inhibitor to modulate the etchant's aggressiveness, the previously harmful uncontrolled etching is transformed into a controlled process that removes the middle layer while preserving the spacer material
2Productivity
If minimum feature sizes are reduced to increase integration density, then more components can be integrated, but etching process challenges increase
Solution Approach 1:
The patent changes the chemical parameters of the etching solution by adding inhibitors, which modifies the etching characteristics to suit smaller feature sizes. This parameter change allows controlled etching at reduced dimensions where traditional etchants would cause excessive damage or variability
3Productivity
If etching rate of spacer material is high, then middle layer removal is fast, but spacer material loss increases
Solution Approach 1:
The inhibitor acts as a protective intermediary that selectively adheres to the spacer material, creating a barrier that prevents the etchant from attacking the spacer. This allows the etching process to proceed at useful speeds while the inhibitor-mediated protection prevents excessive spacer material loss
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 use of inhibitors in the etching solution effectively reduces the loss of spacer material, lowers the aspect ratio of openings, and prevents topographical variations, enhancing the manufacturing process by reducing defects and improving the quality and yield of semiconductor devices.
Implementation Method 1
applying an etchant to be in physical contact with both the middle layer and the spacer material
Implementation Method 2
the etchant comprises an inhibitor which inhibits an etch rate of the spacer material
Data Source
AI summary
A semiconductor device and method of manufacture are provided. After a patterning of a middle layer, the middle layer is removed. In order to reduce or prevent damage to other underlying layers exposed by the patterning of the middle layer and intervening layers, an inhibitor is included within an etching process in order to inhibit the amount of material removed from the underlying layers.