Annular Polysilicon Hard Mask for MRAM Junction Fabrication
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Solution Overview
Problem
The existing methods for manufacturing annular magnetic channel junctions in magneto-resistive memory devices require high-resolution exposure apparatus, leading to increased manufacturing costs and complexity, making it challenging to produce structures with precise dimensions without such equipment.
Innovation Solution
A method involving the deposition of a thin-film magnetic channel junction on a wafer substrate, followed by the formation of silicon oxide and nitride layers, and subsequent etching processes to create a circular photo-resist pattern and an annular polysilicon structure, which serves as a hard mask for forming the annular magnetic channel junction, allowing for production with normal resolution equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-resolution exposure apparatus is used to manufacture annular magnetic channel junctions, then manufacturing precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent introduces a cylindrical polysilicon structure as an intermediary element that serves as a self-aligned mask. This mediator enables the formation of precise annular patterns through simple circular photoresist patterns, eliminating the need for complex high-resolution exposure apparatus while maintaining manufacturing precision
Solution Approach 2:
The patent uses a temporary cylindrical polysilicon structure that is removed after serving its masking function. This disposable structure enables precise annular pattern formation using standard resolution equipment, avoiding the need for expensive high-resolution exposure apparatus
2Manufacturing precision
If high-resolution exposure apparatus is used to manufacture annular magnetic channel junctions, then manufacturing precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent employs a temporary cylindrical polysilicon structure that is inexpensive to create and remove after use. This disposable element enables precise annular pattern formation using standard resolution equipment, significantly reducing manufacturing costs compared to high-resolution exposure apparatus
Solution Approach 2:
The cylindrical polysilicon structure acts as a cost-effective intermediary that translates simple circular patterns into precise annular structures, enabling high manufacturing precision using standard, low-cost equipment
3Device complexity
If conventional photoetching is used without self-aligned structures, then process complexity is reduced, but manufacturing precision deteriorates
Solution Approach 1:
The patent performs preliminary formation of a cylindrical polysilicon structure before the photoetching step. This preliminary structure serves as a self-aligned mask that ensures precise annular pattern formation during subsequent etching, maintaining high manufacturing precision while keeping the overall process relatively simple
Solution Approach 2:
The cylindrical polysilicon structure serves as an intermediary masking element that enables precise annular pattern formation through conventional photoetching, bridging the gap between simple processes and high precision requirements
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 production costs and enhances market competitiveness by enabling the formation of annular structures with precise dimensions using standard resolution photo-etching, thereby lowering economic burdens and improving manufacturing efficiency.
Implementation Method 1
a photo-resist pattern is defined on the silicon nitride layer by photoetching process
Implementation Method 2
the said silicon nitride layer is etched, and the etching process stops at the silicon oxide layer
Implementation Method 3
a poly-silicon thin film is covered on the surface of the wafer to form a poly-silicon layer
Implementation Method 4
the said poly-silicon layer is performed plasma etching back
Data Source
AI summary
The present invention discloses a method of forming an annular storage structure of a magneto-resistive memory. It relates to the manufacturing process of the semiconductor devices. The method includes the following steps: a silicon oxide layer and a silicon nitride layer is formed on the thin-film layer of a magnetic channel junction; a circular silicon nitride trench is formed; a poly-silicon thin film is deposited to cover the silicon nitride trench, the annular poly-silicon structure is formed by plasma etching back; the remaining silicon nitride thin film is removed to form the annular poly-silicon hard mask; the poly-silicon hard mask is used when the magnetic channel junction thin film layer is etched by plasma etching. At last, the unit structure of magnetic channel junction is formed. The advantages of the above technical solutions are: the diameter of the round photo-resist pattern is larger; it is possible to use the photo-etching with normal resolution, thus the method reduces the cost of production enhances market competitiveness and obtains significant economic benefits.