Plasma Wafer Etching With Mask Aspect Ratio Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing etching methods for manufacturing magnetoresistive random access memory (MRAM) devices face challenges in miniaturization due to low selectivity with masks and deposition of sputtered atoms on etching sidewalls, which limits the precision of pattern formation.
Innovation Solution
An etching method using ions in plasma generated by a plasma processing apparatus, where a wafer with a multilayer film and a mask layer is etched, with the aspect ratio of the mask layer satisfying the condition h/D≥1/(tan(φ)−tan(θ)), where θ is the inclination angle of the sidewall and φ is the upper limit of the incidence angle of ions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching methods are used for manufacturing MRAM devices, then etching can be performed on multilayer films, but dimensional increases occur due to deposition of sputtered atoms on sidewalls, limiting pattern formation precision
Solution Approach 1:
The patent changes the physical parameters of the etching process by controlling the aspect ratio of the mask layer (h/D≥1/(tan(φ)−tan(θ))) and adjusting plasma processing conditions. This parameter optimization prevents sputtered atom deposition on sidewalls while maintaining etching effectiveness, thereby improving pattern formation precision without the harmful deposition effects
Solution Approach 2:
The patent converts the potentially harmful sputtering process into a beneficial etching mechanism by carefully controlling the mask layer aspect ratio. The controlled sputtering, when combined with the optimized mask geometry, enables precise pattern transfer while minimizing unwanted material deposition on sidewalls
2Manufacturing precision
If mask layer with insufficient aspect ratio is used, then etching process is simpler, but low selectivity with masks occurs, reducing manufacturing precision
Solution Approach 1:
The patent optimizes the mask layer aspect ratio parameter (h/D) to satisfy the condition h/D≥1/(tan(φ)−tan(θ))). This parameter change enhances mask selectivity during etching, allowing precise pattern transfer while managing the increased structural requirements through controlled geometric design
3Volume of moving object
If further miniaturization of MRAM devices is pursued, then device density increases, but existing etching methods cannot achieve required precision due to sidewall deposition
Solution Approach 1:
The patent applies optimized aspect ratio parameters for the mask layer that enable vertical sidewall formation during etching. This parameter optimization allows for smaller device dimensions while maintaining precise pattern formation, as the controlled geometry prevents material deposition that would otherwise limit miniaturization
Solution Approach 2:
The patent addresses miniaturization challenges by optimizing the vertical dimension (height h of mask layer) relative to the horizontal dimension (distance D between sidewalls). This dimensional optimization creates the necessary aspect ratio to prevent sidewall deposition effects, enabling further device miniaturization while maintaining manufacturing precision
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 dimensional increases caused by deposited films on sidewalls, enabling vertical machining and further miniaturization of MRAM devices while maintaining accurate pattern formation.
Implementation Method 1
ions in plasma generated by a plasma processing apparatus
Implementation Method 2
etching the multilayer film by sputtering using ions in plasma
Data Source
AI summary
An etching method of etching a wafer by sputtering using ions in plasma includes accommodating the wafer in an internal space of a plasma processing apparatus, and etching a multilayer film by sputtering using ions. The wafer includes a multilayer film containing a non-volatile material and a mask layer on a surface of the multilayer film, and an exposed space of a region not covered by the mask layer. An aspect ratio h/D obtained by dividing a height h of the mask layer by a distance D between two adjacent sidewalls of the mask layer satisfies a condition: h/D≥1/(tan (φ)−tan (θ)). θ indicates an inclination angle of the sidewalls with a vertical surface perpendicular to the surface. φ indicates an upper limit of an incidence angle of ions on the vertical surface. φ is larger than θ.