Metal Pattern Forming via Electroless Plating and Wet Etching
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Solution Overview
Problem
The existing methods for forming metal patterns in semiconductor devices face challenges such as insufficient etching selectivity between photoresist and underlayer materials, high manufacturing costs due to dry etching, and significant pattern conversion differences when scaling down hard mask patterns, particularly in three-dimensional memory applications.
Innovation Solution
A metal pattern forming method using electroless plating to create a metal film with a thickness that buries recesses, followed by wet etching to remove the film from recesses and maintain it on protrusions, which then serves as a mask for anisotropic dry etching of the underlayer material, reducing costs and pattern conversion differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If dry etching is used to form a hard mask, then etching precision is improved, but manufacturing cost increases and productivity decreases
Solution Approach 1:
The patent uses a photoresist mask that is intentionally designed to be consumed during the etching process. Instead of using expensive dry etching to create a reusable hard mask, the invention employs a disposable photoresist mask that is removed after serving its purpose, significantly reducing manufacturing costs while maintaining adequate etching precision for the application
Solution Approach 2:
The patent replaces the mechanical/vacuum-based dry etching system with a chemical wet etching system. This substitution eliminates the need for vacuum equipment and complex process control, thereby increasing throughput and reducing manufacturing costs while still achieving the required patterning precision
2Productivity
If wet etching is used to form a hard mask, then productivity is improved, but manufacturing precision deteriorates due to pattern conversion difference
Solution Approach 1:
The patent applies different etching characteristics to different regions of the pattern. By controlling the photoresist mask geometry and etching conditions, the isotropic wet etching process achieves the desired anisotropic-like pattern transfer, maintaining precision while benefiting from wet etching's high throughput
Solution Approach 2:
The patent optimizes etching parameters such as etchant concentration, temperature, and exposure time to control the pattern conversion. By carefully adjusting these parameters, the invention minimizes the difference between the photoresist mask pattern and the final etched pattern, achieving high precision with wet etching
3Ease of manufacture
If photoresist is used as a mask for etching underlayer material, then ease of manufacture is improved, but etching selectivity becomes insufficient
Solution Approach 1:
The patent introduces a metal film as an intermediary layer between the photoresist mask and the underlayer material. This metal film serves as a protective barrier that enhances etching selectivity, allowing the photoresist to remain simple and easy to manufacture while the metal film provides the necessary selectivity control during etching
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 reduces manufacturing costs and effectively forms fine metal patterns close to the design pattern, enhancing etching selectivity and throughput by using wet etching and electroless plating, while maintaining the integrity of the pattern in high aspect ratio structures.
Implementation Method 1
forming a metal film on a surface of a substrate by an electroless plating method
Implementation Method 2
performing wet etching, the metal film in the recess removed by the wet etching
Data Source
AI summary
A metal pattern forming method according to an embodiment includes forming a metal film on a surface of a substrate by an electroless plating method, the substrate including a first layer including a protrusion and a recess, and a film thickness of the metal film being a half or more of a width of the recess; and performing wet etching, the metal film in the recess removed by the wet etching and the metal film on the protrusion remained after the wet etching.