Composite Hard Mask for Ultra-Thin MR Sensor Patterning
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Solution Overview
Problem
Conventional fabrication processes for magnetic sensors like MR sensors face challenges in scaling down sensor size and thickness due to issues like local dishing and long-tail formation, which affect performance and scalability.
Innovation Solution
A composite hard mask comprising a first sacrificial layer of amorphous carbon or silicon nitride and a second sacrificial layer of silicon nitride, silicon oxide, metal, metal oxide, or metal nitride, which allows for improved process integration and precise patterning, enabling the scaling down of MR sensor size and thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional fabrication processes are used for MR sensors, then the manufacturing process is simple, but the sensor cannot be scaled down to ultra-fine critical dimensions and ultra-thin thickness
Solution Approach 1:
The hard mask is divided into two distinct layers: a first sacrificial hard mask layer (amorphous carbon or silicon nitride, 10-150 Å thick) and a second sacrificial hard mask layer (silicon nitride, silicon oxide, metal, metal oxide, or metal nitride, 20-800 Å thick). This segmentation allows each layer to serve specific functions in the fabrication process, enabling precise control of ultra-fine critical dimensions (20 nm or less) and ultra-thin sensor thickness (15 nm or less) while managing process complexity through specialized removal steps for each layer.
2Manufacturing precision
If the first and second sacrificial hard mask layers are made of the same material, then the manufacturing process is simpler, but selective removal cannot be achieved to enable precise patterning
Solution Approach 1:
The patent applies local quality by making the first and second sacrificial hard mask layers different materials with distinct removal characteristics. The first layer (amorphous carbon or silicon nitride) and second layer (silicon nitride, silicon oxide, metal, metal oxide, or metal nitride) can be selectively removed using different etching processes, allowing precise patterning control at different stages of MR sensor fabrication without complicating the overall manufacturing approach.
3Reliability
If single-layer hard masks are used, then the process integration is simpler, but local dishing and long-tail issues occur that affect sensor performance
Solution Approach 1:
The patent employs composite materials by combining two different sacrificial hard mask layers with complementary properties. The first layer (amorphous carbon or silicon nitride, 10-150 Å) and second layer (silicon nitride, silicon oxide, metal, metal oxide, or metal nitride, 20-800 Å) work together to eliminate local dishing and long-tail formation issues during ion beam etching, ensuring reliable sensor performance while maintaining reasonable process integration complexity.
Data Source
AI summary
A composite hard mask is disclosed. In some embodiments, a first sacrificial hard mask layer comprising an amorphous carbon or silicon nitride and a second sacrificial hard mask layer comprising a silicon nitride, silicon oxide, metal, metal oxide, or metal nitride, wherein the first and second sacrificial hard mask layers are not made of the same material.