MRAM Spacer Design for Etch Selectivity
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Solution Overview
Problem
Conventional MRAM cell structures face manufacturing yield issues due to the magnetic tunneling junction being enveloped by the M1 line on three sides, leading to potential shorting and device malfunction.
Innovation Solution
Incorporating spacers made of silicon nitride around the magnetic tunneling junction with a dielectric etch stop layer, such as silicon carbon nitride, to create a protective barrier that prevents the M1 line from contacting the fixed layer, ensuring proper etch selectivity and minimizing the risk of shorting during the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the M1 line is routed to contact the fixed layer on three sides for compact layout, then device density is improved, but manufacturing yield deteriorates due to potential shorting of the magnetic tunneling junction
Solution Approach 1:
A dielectric etch stop layer is introduced as an intermediary between the M1 line and the fixed layer of the magnetic tunneling junction. This etch stop layer acts as a protective barrier that prevents direct contact and potential shorting during manufacturing processes, while still allowing the M1 line to maintain its compact three-sided contact configuration with the fixed layer for high device density
Solution Approach 2:
The dielectric etch stop layer is deposited in advance before final M1 line formation and subsequent etching processes. This preliminary protective layer is strategically positioned to prevent potential shorting that could occur during manufacturing, ensuring manufacturing yield is maintained while the compact layout is preserved
2Reliability
If spacers and etch stop layers are added to protect the magnetic tunneling junction, then manufacturing yield is improved, but device complexity increases
Solution Approach 1:
The protective dielectric etch stop layer and spacers are applied locally only where needed - specifically around the magnetic tunneling junction and at critical contact points with the M1 line. This localized approach provides manufacturing protection without adding unnecessary complexity to the entire device structure, maintaining simplicity in non-critical areas
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
The solution effectively protects the magnetic tunneling junction, preventing shorting and ensuring the MRAM cell's functionality by allowing the M1 line to contact only the top surface of the storage layer, thereby enhancing the manufacturability and reliability of the semiconductor device.
Implementation Method 1
The spacer comprises spacer material that has at least some etch selectivity compared to a dielectric material that surrounds at least a portion of the first conductive material
Implementation Method 2
The etch stop material may have at least some etch selectivity compared to the dielectric material and at least some etch selectivity compared to the spacer material
Implementation Method 3
The electrical resistance of the magnetic tunneling junction changes based on the relative orientation of the electron spin in the fixed and storage layers
Data Source
AI summary
A semiconductor device comprises a first conductive material, a contact, an a magnetic tunneling junction positioned between the first conductive material and the contact. The semiconductor device further comprises a spacer that is positioned between the first conductive material and the contact and surrounds at least a portion of the magnetic tunneling junction. The spacer comprises spacer material that has at least some etch selectivity compared to a dielectric material that surrounds at least a portion of the first conductive material.