MTJ Top Contact via CMP and Encapsulating Layer
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Solution Overview
Problem
Conventional etching processes used in fabricating magnetic tunnel junction (MTJ) structures for MRAM devices often damage the structures and result in poor electrical contact with the top electrode.
Innovation Solution
The method involves forming a magnetic tunnel junction structure, depositing an encapsulating layer on top and sides, followed by a chemical mechanical planarization (CMP) process to expose the top, and then adding a second contact layer, which avoids damage and improves electrical contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional etching processes are used to pattern the MTJ structure, then the MTJ structure can be formed, but the etching processes damage the MTJ structure and result in poor electrical contact
Solution Approach 1:
An encapsulating layer is deposited over the MTJ structure before patterning. This encapsulating layer serves as a mediator that protects the MTJ structure during subsequent etching processes. The encapsulating layer is selectively removed to expose the MTJ structure, allowing pattern formation without direct etching contact that would damage the MTJ and compromise electrical contact.
2Ease of operation
If etching processes are used to expose the top of the MTJ structure, then the structure can be accessed, but the MTJ structure is damaged in the process
Solution Approach 1:
The encapsulating layer is deposited in advance over the MTJ structure before any patterning or exposure steps. This preliminary protective action allows subsequent processing steps to access the MTJ structure through openings in the encapsulating layer without directly etching the MTJ itself, thereby maintaining structural integrity while enabling accessibility.
Solution Approach 2:
The encapsulating layer acts as an intermediary protective barrier during patterning operations. It allows the MTJ structure to be accessed and patterned indirectly through selective removal of the encapsulating layer, rather than direct etching of the MTJ structure, thus preserving manufacturing precision.
3Ease of manufacture
If the MTJ structure is exposed by removing encapsulating material, then the top contact can be deposited, but conventional methods cause damage and poor contact
Solution Approach 1:
The encapsulating layer is used as a protective intermediary that remains in place during contact layer deposition planning. The encapsulating layer is selectively removed only where contact is needed, and the contact layer is deposited onto the exposed MTJ structure. This approach ensures clean exposure without etching damage, enabling reliable electrical contact while maintaining ease of manufacture.
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 prevents damage to the MTJ structure and enhances electrical contact, leading to improved performance and reliability of the memory devices.
Implementation Method 1
removing the encapsulating layer disposed on the top of the magnetic tunnel junction by a chemical mechanical planarization process to expose the top of the magnetic tunnel junction structure
Data Source
AI summary
Embodiments of the disclosure relate to methods for fabricating structures used in memory devices. More specifically, embodiments of the disclosure relate to methods for fabricating MTJ structures in memory devices. In one embodiment, the method includes forming a MTJ structure, depositing a encapsulating layer on a top and sides of the MTJ structure, depositing a dielectric material on the encapsulating layer, removing the dielectric material and the encapsulating layer disposed on the top of the MTJ structure by a chemical mechanical planarization (CMP) process to expose the top of the MTJ structure, and depositing a contact layer on the MTJ structure. The method utilizes a CMP process to expose the top of the MTJ structure instead of an etching process, which avoids damaging the MTJ structure and leads to improved electrical contact between the MTJ structure and the contact layer.