MRAM Interconnect Structure for Dense 3D Memory Cell Integration
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Solution Overview
Problem
Current integrated circuit manufacturing processes for data storage elements, such as MRAM cells, face challenges in efficiently integrating magnetic tunnel junctions (MTJs) and spin-orbit torque (SOT) layers within tightly-packed arrays, which affects data retention and power consumption.
Innovation Solution
The proposed semiconductor device incorporates a semiconductor substrate with transistors and a complex interconnect structure featuring multiple interlayer dielectric layers, vias, and memory cells. This structure allows for the efficient electrical connection of memory cells with transistors through vias, optimizing space and reducing resistance between routing lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If data storage elements are placed in tightly-packed arrays to minimize die area, then area efficiency is improved, but manufacturing complexity and integration difficulty increase
Solution Approach 1:
The patent transitions from planar 2D integration to 3D vertical integration by stacking multiple interlayer dielectric layers (ILD1, ILD2, ILD3) with vias penetrating through them. This dimensional change allows memory cells to be connected to transistors through vertical vias rather than horizontal routing, enabling tighter packing while maintaining manufacturability through standardized vertical via processes.
Solution Approach 2:
The patent implements nested structures where vias are formed within interlayer dielectric layers, and memory cells are integrated within the transistor structure. The via structure is nested within the ILD layers, and the memory cell is nested within the overall device architecture, allowing efficient space utilization without excessive complexity.
2Quantity of substance
If magnetic tunnel junctions and spin-orbit torque layers are integrated in tightly-packed arrays, then storage density is improved, but data retention and power consumption are adversely affected
Solution Approach 1:
The patent applies different dielectric materials with different properties to different regions and layers. ILD1 has different properties from ILD2 and ILD3, allowing optimization of local electrical characteristics. This local quality differentiation enables better control of electrical fields around individual memory cells, improving data retention even in high-density configurations.
Solution Approach 2:
The patent divides the integration structure into distinct segments: separate interlayer dielectric layers (ILD1, ILD2, ILD3), distinct via regions, and separated memory cell units. This segmentation isolates adjacent memory cells electrically, preventing cross-talk and maintaining data integrity in high-density arrays, thus improving data retention.
3Adaptability or versatility
If multiple interlayer dielectric layers and vias are used to connect memory cells with transistors, then routing capacity and space efficiency are improved, but manufacturing complexity increases
Solution Approach 1:
The via structure serves multiple functions: it acts as an electrical connection conduit, a spacing element between layers, and a alignment reference for subsequent processing steps. This multi-functionality reduces the need for additional specialized structures, simplifying manufacturing despite the multi-layer architecture.
Solution Approach 2:
The interlayer dielectric layers and vias are formed in a predetermined sequence during the fabrication process, with each layer prepared in advance for subsequent steps. This preliminary structuring allows standard semiconductor manufacturing processes to be applied systematically, reducing manufacturing complexity despite the sophisticated final structure.
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 configuration enhances data retention and reduces power consumption in MRAM cells by allowing for more flexible layout design and improved routing capacity, while maintaining efficient electrical connections.
Implementation Method 1
Magnetoresistive Random Access Memory (MRAM) is a type of data storage element in which information is stored based on the orientation of a magnetic field in a circuit element. MRAM uses the magnetic field to store information rather than the presence/absence of electrical charge in a storage circuit element
Implementation Method 2
Magnetoresistive Random Access Memory (MRAM) is a type of data storage element in which information is stored based on the orientation of a magnetic field in a circuit element
Data Source
AI summary
A semiconductor device including a semiconductor substrate and an interconnect structure is provided. The semiconductor substrate includes a transistor, wherein the transistor has a source region and a drain region. The interconnect structure is disposed over the semiconductor substrate, wherein the interconnect structure includes a plurality of interlayer dielectric layers, a first via and a memory cell. The plurality of interlayer dielectric layers are over the semiconductor substrate. The first via is embedded in at least two interlayer dielectric layers among the plurality of interlayer dielectric layers and electrically connected with the drain region of the transistor. The memory cell is disposed over the at least two interlayer dielectric layers among the plurality of interlayer dielectric layers and electrically connected with the first via.