Electron-Enhanced Silicon Etching with Positive Substrate Bias
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Solution Overview
Problem
Existing etching processes for silicon and other materials lack atomic layer precision, are prone to uneven etching due to surface morphology variations, and require high thermal budgets, leading to substrate damage and non-uniform etching.
Innovation Solution
Electron-Enhanced Chemical Vapor Etching (EE-CVE) uses electrons to activate chemical reactions at low temperatures without thermal or direct plasma, employing hydrogen as a reactive background gas to create reactive species that etch films like silicon, silicon germanium, and germanium with high selectivity and precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If thermal atomic layer etching is used to etch silicon, then etching can be achieved, but uniform etch rates are difficult to achieve due to surface morphology variations and local temperature fluctuations
Solution Approach 1:
The patent replaces thermal activation with electron beam activation. Instead of using high temperature thermal fields to activate the etching process, electron beams are used to directly activate chemical reactions at room temperature or low temperature, thereby avoiding temperature-related non-uniformity while achieving precise etching control
Solution Approach 2:
The patent changes the activation parameter from temperature to electron beam energy. By controlling electron beam parameters (energy, flux, pulse duration) instead of temperature, the process achieves atomic-layer precision etching without the thermal budget constraints and temperature-induced non-uniformity
2Productivity
If high thermal budget is used for etching, then etching process can proceed, but substrate damage and stress are introduced
Solution Approach 1:
The patent substitutes thermal energy with electron beam energy for process activation. The electron beam provides the necessary activation energy for chemical reactions without the harmful thermal effects, enabling high etch rates without substrate damage or stress
Solution Approach 2:
The patent introduces electron beams as an intermediary activation mechanism. Instead of directly heating the substrate, electron beams interact with precursor molecules to generate reactive species that perform the etching, thereby decoupling the activation process from thermal effects that cause damage
3Manufacturing precision
If direct plasma is used for etching, then etching can be achieved, but energetic ion bombardment causes substrate damage
Solution Approach 1:
The patent replaces direct plasma ion bombardment with electron beam activation. Instead of using ion kinetic energy to drive etching, electron beams activate chemical reactions that proceed without ion bombardment, achieving precise etching without the associated substrate damage
Solution Approach 2:
The patent converts the harmful effect of plasma (ion bombardment) into a beneficial process by using electron beams to activate chemistry. The electron beam provides activation energy without the mechanical damage of ion impact, effectively converting a harmful physical process into a beneficial chemical process
4Productivity
If corrosive gases are used for etching, then etching can be achieved, but substrate damage and contamination occur
Solution Approach 1:
The patent changes the chemical environment from corrosive to benign by using electron beam activation with non-corrosive precursor gases. The electron beam provides the activation energy that would otherwise require corrosive chemistry, enabling high etch rates with harmless gases that leave no residue or damage
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
EE-CVE achieves precise etching of silicon and other materials at room temperature, avoiding substrate damage and ensuring uniform etch rates, with no nucleation delay and high selectivity for silicon over silicon dioxide, enabling advanced semiconductor fabrication.
Implementation Method 1
electrons are used to dissociate the background gas molecules and create reactive species that can react with the film to be etched
Implementation Method 2
A positive substrate bias is used to attract the secondary electrons to the surface, hence improving the effectiveness of the reactions with the reactive background gas
Data Source
AI summary
A method for etching a thin film includes conducting electron-enhanced chemical vapor etching with at least one reactive background gas and electrons to etch a thin film on a substrate with a positive substrate voltage. In an embodiment, the method is a method for etching a silicon thin film, including conducting electron-enhanced chemical vapor etching with at least one reactive background gas and electrons to etch a silicon thin film on a substrate with a positive substrate voltage.