Multilayer Etching Mask for High-Aspect-Ratio Memory Holes
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Solution Overview
Problem
The manufacturing of stacked-type semiconductor memory devices faces challenges in achieving high etching resistance and preventing wafer warp due to high aspect ratios of memory holes, which existing technologies struggle to address effectively.
Innovation Solution
A method involving the formation of a multilayer stacked film with carbon-containing tungsten films and tungsten films, where the carbon-containing tungsten films act as a stress-decoupling layer to reduce compressive stress and enhance etching resistance, allowing for the formation of memory holes with accurate shape and reduced deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of layers stacked in the stacked body increases, then the memory capacity is improved, but the aspect ratio of the memory hole becomes high and etching resistance is insufficient
Solution Approach 1:
The mask film is divided into multiple layers (first mask film, second mask film, third mask film) with different materials and functions. The first mask film provides etching resistance, the second mask film controls etching speed, and the third mask film prevents wafer warp, collectively solving the etching resistance problem for high-aspect-ratio holes
Solution Approach 2:
The mask film uses a composite structure combining different materials (e.g., tungsten-based materials with different carbon concentrations, or tungsten with molybdenum) to achieve both high etching resistance and wafer warp prevention simultaneously, which cannot be achieved with a single material
2Reliability
If a thick mask film is used to improve etching resistance, then etching resistance is improved, but wafer warp occurs due to compressive stress
Solution Approach 1:
The mask film is segmented into multiple thin layers instead of one thick layer. Each layer has controlled thickness to limit compressive stress accumulation while collectively providing sufficient etching resistance through the combined structure
Solution Approach 2:
The composition parameters of the mask film layers are adjusted (e.g., varying carbon concentration in tungsten-based materials, or using different metal ratios) to control the stress state of each layer, transforming the overall stress from compressive to tensile or neutral
3Device complexity
If a single-layer mask film is used to simplify the structure, then device complexity is reduced, but both etching resistance and wafer warp control cannot be achieved simultaneously
Solution Approach 1:
Each layer of the multi-layer mask film serves multiple functions: the first layer provides etching resistance, the second layer controls etching speed, and the third layer prevents wafer warp. This multi-functional design achieves multiple goals simultaneously without requiring separate structures for each function
Solution Approach 2:
Different regions of the mask film structure have different material compositions and properties tailored to specific local requirements: the bottom layer has high etching resistance for deep hole formation, the middle layer has controlled etching speed for uniform progression, and the top layer has stress-control properties for wafer flatness
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 approach enables the formation of semiconductor devices with improved etching resistance and reduced wafer warp, facilitating easier manufacturing and accurate memory hole formation, while maintaining high etching efficiency and preventing exfoliation of the etching mask.
Implementation Method 1
the carbon-containing tungsten films act as a stress-decoupling layer to reduce compressive stress
Implementation Method 2
memory holes penetrating a stacked body are formed by etching
Data Source
AI summary
A method of manufacturing a semiconductor device according to one embodiment includes forming a first film including a first metal above a processing target member. The method includes forming a second film including two or more types of element out of a second metal, carbon, and boron above the first film. The method includes forming a third film including the first metal above the second film. The method includes forming a mask film by providing an opening part to a stacked film including the first film, the second film and the third film. The method includes processing the processing target member by performing etching using the mask film as a mask.