Wet Atomic Layer Etching for Polycrystalline Surface Uniformity
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Solution Overview
Problem
Existing etching techniques face challenges in achieving microscopic and macroscopic uniformity, particularly when processing polycrystalline materials, leading to surface roughening and non-uniform material removal rates, which are critical issues as feature sizes decrease.
Innovation Solution
A wet atomic layer etching (ALE) process using sequential, self-limiting reactions to modify and selectively remove surface layers, involving chemical modification with oxidizing agents and passivation using complexing agents, followed by solvent rinses to control the etch process, ensuring uniformity and precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional wet etching or plasma etching is used, then material removal is achieved, but surface roughening and non-uniform etch rates occur particularly on polycrystalline materials
Solution Approach 1:
The etching process is segmented into discrete cyclic steps: surface modification step followed by removal step. Each cycle removes a controlled thickness corresponding to the modified layer, enabling precise thickness control and uniform etching across the substrate surface.
Solution Approach 2:
The patent employs periodic cyclic processing where the substrate undergoes repeated sequences of surface modification and removal. This periodic action ensures consistent material removal rate and maintains surface smoothness throughout the etching process by resetting the surface state in each cycle.
2Productivity
If aggressive oxidants are used for sequential etching of III-V semiconductors, then material removal is achieved, but atomic layer control is lost
Solution Approach 1:
The patent modifies the chemical parameters of the etching process by using controlled oxidizing conditions and specific chemical compositions that enable self-limiting reactions. This allows the process to achieve both reasonable etch rates and precise atomic layer control through thermodynamically controlled surface modification.
Solution Approach 2:
The self-limiting nature of the surface modification reaction provides inherent feedback control. The reaction automatically stops when the desired modified layer thickness is reached, preventing over-etching and enabling precise atomic layer control without requiring aggressive oxidants.
3Manufacturing precision
If ALE processes are performed in vacuum or gas phase with plasma or high-temperature reactions, then atomic precision etching is achieved, but process complexity and equipment requirements increase
Solution Approach 1:
The patent replaces the mechanical vacuum system with a liquid-phase chemical processing system. By using wet chemistry reactions in atmospheric conditions, the process achieves atomic precision etching without requiring complex vacuum equipment, plasma generators, or high-temperature reaction chambers.
Solution Approach 2:
The patent uses liquid-phase chemicals and solution-based reactions to achieve the etching process. The hydraulic delivery of chemical solutions replaces the pneumatic plasma delivery systems, simplifying the equipment while maintaining atomic layer control through self-limiting chemical reactions.
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 wet ALE process effectively prevents surface roughening and achieves uniform material removal, maintaining surface smoothness and improving wafer-scale uniformity, offering precise control over the etch amount and surface roughness.
Implementation Method 1
chemical modification of a surface of the polycrystalline material by exposing the surface to a chemical solution to provide a modified surface layer
Implementation Method 2
selective removal of the modified surface layer of the polycrystalline material by exposing the modified surface layer to a liquid-phase chemical solution
Data Source
AI summary
A processing system and platform for improving both the microscopic and macroscopic uniformity of materials during etching is disclosed herein. These improvements may be accomplished through the formation and dissolution of thin, self-limiting layers on the material surface by the use of wet atomic layer etching (ALE) techniques. For etching of polycrystalline materials, these self-limiting reactions can be used to prevent this roughening of the surface during etching. Thus, as disclosed herein, a wet ALE process uses sequential, self-limiting reactions to first modify the surface layer of a material and then selectively remove the modified layer.