Stacked Semiconductor Etching With Sidewall Protective Layers
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Solution Overview
Problem
The etched profile of deep holes in multilayer stacked semiconductor structures is non-collimated, limiting structural layout and performance improvement due to defects such as notches in sidewalls during the etching process.
Innovation Solution
A method involving the use of fluoride ions for etching and simultaneous introduction of silicon and oxygen ions to form protective layers on sidewalls of openings in stacked semiconductor structures, ensuring perpendicularity and integrity of the etched profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching is used to form deep holes in stacked structures, then the etching process can be completed, but the etched profile becomes non-collimated with defects such as notches in sidewalls
Solution Approach 1:
A protective layer is formed on the sidewalls of openings before performing the etching process. This preliminary protective action prevents etching gas from attacking the sidewalls, thereby maintaining collimation and preventing notch formation during subsequent etching of deep holes through stacked structures.
Solution Approach 2:
The protective layer acts as an intermediary between the etching gas and the sidewall material. It temporarily protects the sidewall during etching, allowing the etching process to proceed while maintaining profile integrity. The protective layer can be selectively removed afterward to reveal the precisely etched structure.
2Quantity of substance
If the number of stacked layers is increased to improve device density, then device density increases, but the etching profile defects become more severe
Solution Approach 1:
Before etching through multiple stacked layers, protective layers are formed on all sidewalls that will be exposed during etching. This preliminary protection enables the etching process to penetrate through more layers while maintaining profile quality, thus allowing increased device density without sacrificing etching precision.
Solution Approach 2:
The solution moves from a two-dimensional planar etching approach to a three-dimensional approach by forming protective layers on vertical sidewalls. This dimensional change allows simultaneous protection of multiple surfaces during deep etching through stacked structures, enabling higher layer counts with maintained profile quality.
3Manufacturing precision
If protective layers are formed on sidewalls during etching, then sidewall integrity and collimation are maintained, but the process complexity increases
Solution Approach 1:
The formation of protective layers is merged with the etching process sequence, where protective layers are deposited and then etching is performed in an integrated workflow. This combination, while adding steps, creates a systematic approach that maintains sidewall integrity throughout the etching of deep holes through stacked structures.
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 method enhances the structural layout and performance of semiconductor devices by maintaining the integrity and collimation of sidewalls, increasing device density and optimizing the structural design.
Implementation Method 1
etching the stacked structure using a first etching gas to form a first opening that penetrates through the second material layer, wherein the first etching gas comprises fluoride ions
Implementation Method 2
introducing a first protective gas and a first auxiliary gas simultaneously into the first opening for reaction to form a protective layer on a sidewall of the first opening, wherein the first protective gas comprises silicon ions, and the first auxiliary gas comprises oxygen ions
Data Source
AI summary
A forming method includes: forming a stacked structure on a substrate, where the stacked structure includes a first material layer and a second material layer; etching the stacked structure using a first etching gas to form a first opening penetrating through the second material layer, wherein the first etching gas includes fluoride ions; introducing a first protective gas and a first auxiliary gas simultaneously into the first opening for reaction to form a protective layer on a sidewall of the first opening; etching the stacked structure using the first etching gas to form a second opening penetrating through the first material layer; and introducing the first protective gas and the first auxiliary gas simultaneously into the second opening for a reaction to form a protective layer on a sidewall of the second opening.