Conformal Vapor-Layer Etching for High Aspect Ratio Structures
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Solution Overview
Problem
High aspect ratio structures in semiconductor substrates pose challenges to wet clean and wet etch efficiency due to reduced diffusion and surface charge layer overlap in geometrically confined spaces, limiting the effectiveness of existing cleaning and etching processes.
Innovation Solution
A method involving the formation of a conformal liquid layer on substrate surfaces through gas or vapor phase pre-treatment with a solvent and reactive gas, including halogen species, which enhances cleaning and etching efficiency by forming a reactive liquid layer that etches exposed surfaces without residue, using a processing chamber with controlled pressure and temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional wet clean chemistry is used on high aspect ratio structures, then the cleaning process can be performed, but the etch rate is limited and residue forms due to reduced diffusion and surface charge layer overlap in geometrically confined spaces
Solution Approach 1:
The patent changes the physical and chemical parameters of the cleaning/etching process by using vapor phase solvents at controlled temperatures (0-400°C) and pressures (1-10 Torr), transforming traditional liquid wet chemistry into a vapor-phase process that achieves higher etch rates (10-100 Angstroms/min) while eliminating residue formation in HAR structures
Solution Approach 2:
The patent utilizes phase transitions by supplying solvents and reactive gases in vapor phase that condense to form conformal liquid layers on substrate surfaces, then evaporate after completing the cleaning/etching function. This phase change mechanism enables the process to overcome diffusion limitations in HAR structures while maintaining uniform coverage
2Manufacturing precision
If conventional wet etching is applied to high aspect ratio structures, then etching can occur, but selectivity and uniformity are reduced due to geometric confinement effects
Solution Approach 1:
The patent employs vapor phase delivery of solvents and reactive gases that can penetrate and conformally coat high aspect ratio structures through vapor diffusion and condensation, achieving uniform etching throughout the HAR geometry without the flow distribution problems that plague liquid wet etching in confined spaces
Solution Approach 2:
The patent applies preliminary vapor phase pretreatment with solvents to prepare and activate surfaces before the main reactive gas etching step, ensuring uniform reaction conditions are established throughout HAR structures before etching begins, which improves both uniformity and overall etch rate
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 achieves a higher etch rate (10-100 Angstroms/min) and improved selectivity compared to traditional wet clean chemistry, with the ability to etch high aspect ratio structures without forming residue, while maintaining uniformity and control through cyclic processing.
Implementation Method 1
supplying at least one of a vaporized solvent and a gas mixture to the processing chamber to form a conformal liquid layer of the solvent on exposed surfaces of the substrate
Implementation Method 2
The conformal liquid layer adsorbs the reactive gas to form a reactive liquid layer
Data Source
AI summary
A method for treating a substrate includes arranging a substrate in a processing chamber. At least one of a vaporized solvent and a gas mixture including the solvent is supplied to the processing chamber to form a conformal liquid layer of the solvent on exposed surfaces of the substrate. The at least one of the vaporized solvent and the gas mixture is removed from the processing chamber. A reactive gas including a halogen species is supplied to the processing chamber. The conformal liquid layer adsorbs the reactive gas to form a reactive liquid layer that etches the exposed surfaces of the substrate.