Magnetic Memory Contact Plug Segmentation for Yield
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Solution Overview
Problem
Current magnetic memory technologies face challenges in improving manufacturing yield and reliability due to high aspect ratios of contact plugs and potential short-circuits caused by conductive residues, which affect the performance and size of memory cells.
Innovation Solution
A two-stage contact plug structure comprising a lower plug and an upper plug with different materials and dimensions is used in the source line-side contact, reducing the aspect ratio and increasing the distance between the magnetoresistive effect element and the contact plug, while a side wall insulation film with a large thickness is employed to prevent short-circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a single contact plug structure is used to connect the source line to the source/drain diffusion layer, then the memory cell size can be reduced, but the aspect ratio of the contact plug becomes high and short-circuits may occur due to conductive residues
Solution Approach 1:
The contact plug is divided into two separate plugs: a first contact plug extending from the source line to a first depth, and a second contact plug extending from the source line to a second depth greater than the first depth. This segmentation allows each plug to have a lower aspect ratio while achieving the same overall connection function, thereby reducing the risk of short-circuits and improving manufacturing yield without increasing memory cell size
Solution Approach 2:
The dual-contact-plug structure introduces a dimensional differentiation in the vertical direction by having two plugs at different depths. This dimensional change allows the contact structure to achieve reliable electrical connection while maintaining a compact footprint, effectively resolving the contradiction between small cell size and high aspect ratio
2Reliability
If the contact plug extends deep into the substrate to ensure good electrical contact, then the electrical connection is improved, but the aspect ratio increases and the risk of short-circuits increases
Solution Approach 1:
The electrical connection function is segmented across two contact plugs at different depths. The first contact plug provides connection at a shallower level while the second contact plug provides connection at a deeper level, ensuring robust electrical connection without requiring a single high-aspect-ratio plug
Solution Approach 2:
The first contact plug acts as an intermediary structure between the source line and the deeper second contact plug. This intermediary plug simplifies the overall structure by providing a staged connection approach, reducing the complexity compared to a single deep-plug design while ensuring reliable electrical connection
3Area of stationary object
If the distance between the magnetoresistive effect element and the contact plug is reduced to increase density, then the memory cell size is reduced, but the manufacturing precision requirements increase due to high aspect ratio
Solution Approach 1:
The contact path is segmented into two plugs at different depths, which reduces the aspect ratio of each individual plug. This segmentation lowers the manufacturing precision requirements for each plug formation step, as shallower plugs are easier to fabricate with consistent dimensions and fewer defects
Solution Approach 2:
By utilizing the vertical dimension with two plugs at different depths, the design maintains compact horizontal spacing while improving manufacturability. The dimensional differentiation in depth allows for easier fabrication control and reduced precision requirements compared to a single deep plug
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 enhances the manufacturing yield and reliability of magnetic memory by reducing the aspect ratio of contact plugs, preventing short-circuits, and maintaining a compact memory cell size.
Implementation Method 1
a magnetoresistive effect element as a memory element on the first contact... Depending on the magnetization states of the two magnetic layers of the magnetoresistive effect element, that is, depending on whether the spin directions of the two magnetic layers are parallel or antiparallel, '1' or '0' information is stored in the memory cell
Data Source
AI summary
According to one embodiment, a magnetic memory includes a cell transistor including a first source/drain diffusion layer and a second source/drain diffusion layer, a first contact on the first source/drain diffusion layer, a memory element on the first contact, and a second contact on the second source/drain diffusion layer, the second contact including a first plug on the second source/drain diffusion layer, and a second plug on the first plug.