Continuous Bottom Electrode Layout for Dense Magnetic Memory Cells
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Solution Overview
Problem
The miniaturization of magnetic memory devices poses challenges in processing memory cells, leading to difficulties in achieving reliable magnetoresistance effect elements with consistent characteristics, particularly due to misalignment issues during manufacturing that can result in etching damage and deterioration of magnetoresistance effect element characteristics.
Innovation Solution
The magnetic memory device design incorporates a series connection of a magnetoresistance effect element and a selector, with a continuous bottom electrode pattern on the wiring connecting adjacent memory cells, and uses a common mask pattern for patterning to align the first and second wiring patterns, ensuring the selector material layer is only partially etched to prevent damage to the magnetoresistance effect element, thereby maintaining its reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If microminiaturization of elements is advanced to increase integration density, then device capacity is improved, but processing of memory cells becomes difficult and manufacturing precision deteriorates
Solution Approach 1:
The patent merges the bottom electrode layer with the wiring layer by making them continuous and coincident in pattern. This integration reduces the number of separate patterning steps required and ensures that the bottom electrode automatically aligns with the wiring, thereby maintaining manufacturing precision even as device dimensions are reduced for higher integration density.
Solution Approach 2:
The continuous bottom electrode pattern serves multiple functions: it acts as both the electrical connection wiring and the bottom electrode for the magnetoresistance effect element. This multi-functionality simplifies the overall structure and reduces the complexity of processing steps, enabling scalable microminiaturization without proportionally increasing manufacturing difficulty.
2Ease of manufacture
If common mask pattern is used for patterning wiring and bottom electrode to improve ease of manufacture, then manufacturing process is simplified, but misalignment may occur during manufacturing
Solution Approach 1:
By making the wiring pattern and bottom electrode pattern coincident and continuous, the patent eliminates the need for separate patterning steps. The single common mask pattern used for patterning both layers ensures they are formed simultaneously with identical geometry, thereby preventing misalignment while maintaining ease of manufacture.
Solution Approach 2:
The bottom electrode layer is formed and patterned in advance as part of the wiring structure, before the magnetoresistance effect element is fully assembled. This preliminary formation ensures that the bottom electrode is already in its final position and configuration, so subsequent processing steps do not require additional alignment operations that could introduce misalignment errors.
3Object-generated harmful factors
If selector material layer is completely etched to remove it, then manufacturing cleanliness is improved, but etching damage occurs to magnetoresistance effect element
Solution Approach 1:
The patent selectively removes only the excess selector material layer that extends beyond the memory cell region, while preserving the selector material layer that is integral to the magnetoresistance effect element structure. This selective extraction maintains manufacturing cleanliness by removing unwanted material while protecting the functional elements from etching damage through the continuous bottom electrode configuration.
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 effectively prevents etching damage to the magnetoresistance effect elements, ensuring they maintain appropriate characteristics and functionality even in the presence of misalignment during manufacturing, thereby enhancing the reliability and performance of the magnetic memory device.
Implementation Method 1
a magnetoresistance effect element (31) including a storage layer (31a) having a variable magnetization direction, a reference layer (31b) having a fixed magnetization direction, and a tunnel barrier layer (31c) provided between the storage layer (31a) and the reference layer (31b)
Implementation Method 2
a spin transfer torque switching element (32) including a bottom electrode (32a) provided on the first wiring (10) side, a top electrode (32b) provided on the magnetoresistance effect element (31) side, and a switching material layer (32c) provided between the bottom electrode (32a) and the top electrode (32b)
Data Source
AI summary
According to one embodiment, a magnetic memory device includes first and second wirings, and memory cells between the first and second wirings, and each including a switching element and a magnetoresistance effect element, the switching element being connected to a first wiring, and the magnetoresistance effect element being connected to a second wiring. The switching element includes a bottom electrode, a top electrode, and a switching material layer between the bottom and top electrodes, and the bottom electrode included in each of the memory cells adjacent to each other in a first direction is continuously provided on the first wiring connecting the memory cells adjacent to each other in the first direction.