Hard Mask Film for Magnetic Sensor Dimension Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for forming 3D magnetic sensors face challenges in precisely controlling the dimensions of the tantalum nitride and magnetic resistive layers due to shadow effects and uneven photoresist layer thickness, leading to larger than designed dimensions and difficulty in uniformity across the wafer surface.
Innovation Solution
The method involves forming a hard mask film on the tantalum nitride film, followed by an isotropic dry etching process using a specific etching gas mixture and RF power settings, which allows for the effective removal of the hard mask film on unused sidewalls and precise etching of the tantalum nitride and magnetic films, avoiding shadow effects and enabling better control over the dimensions of the magnetic sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional photoresist etching method is used, then the process is simple, but shadow effects occur and dimension control precision deteriorates
Solution Approach 1:
A hard mask film is introduced as an intermediary layer between the photoresist and the tantalum nitride film. The photoresist defines the pattern, transfers it to the hard mask film through isotropic dry etching, and then the hard mask film serves as the actual etching mask for the tantalum nitride film. This intermediary hard mask film eliminates shadow effects during the critical etching step while maintaining process feasibility.
Solution Approach 2:
The etching process is segmented into two distinct stages: first, isotropic dry etching of the hard mask film using photoresist as mask; second, etching of the tantalum nitride film using the formed hard mask film as mask. This segmentation allows each step to be optimized independently, with the first step creating a uniform hard mask layer and the second step achieving precise dimension control without shadow effects.
2Area of stationary object
If photoresist layer thickness is increased to cover groove depth, then coverage is improved, but thickness uniformity deteriorates
Solution Approach 1:
The hard mask film acts as an intermediary that receives the pattern from the photoresist and transfers it to the underlying layers. The photoresist only needs to provide pattern definition on the hard mask film surface, not extend deep into the groove. The hard mask film then serves as the functional mask during etching, eliminating the need for excessively thick photoresist while maintaining complete coverage and pattern fidelity.
3Manufacturing precision
If isotropic dry etching is used for hard mask film, then shadow effects are eliminated, but process complexity increases
Solution Approach 1:
The hard mask film serves as an intermediary layer that enables the use of isotropic dry etching with controlled parameters. By optimizing the etching gas composition (oxygen and fluorine-contained gases), flow rates, and RF power settings, the isotropic etching process achieves uniform hard mask film removal without shadow effects. The hard mask film thickness and material properties are tuned to work specifically with these isotropic etching conditions.
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 allows for the precise formation of 3D magnetic sensors with dimensions equal to the hard mask layer, facilitating easier regulation and preventing shadow effects, thus ensuring accurate and uniform sensor dimensions.
Implementation Method 1
implementing an isotropic dry etching process to the hard mask film by taking the photoresist layer as a mask
Implementation Method 2
implementing an isotropic dry etching process to the hard mask film
Implementation Method 3
implementing an etching process to the tantalum nitride film and the magnetic film successively by taking the hard mask layer as a mask
Data Source
AI summary
A method for forming a magnetic sensor includes: forming a hard mask film on a tantalum nitride film; forming a patterned photoresist layer on the hard mask film; implementing an isotropic dry etching process to the hard mask film by taking the photoresist layer as a mask, so as to form a hard mask layer; and implementing an etching process to the tantalum nitride film and the magnetic film by taking the hard mask layer as a mask, so as to form a tantalum nitride layer and a magnetic resistive layer. As an isotropic dry etching process is implemented to the hard mask film, the hard mask film located which is above the other sidewalls and is not used for forming the magnetic sensor can be effectively removed. In addition, shadow effect will not take place, thus dimension of the magnetic sensor formed is able to be easily controlled.