MTJ Storage Elements on an Inclined Underlayer for Etch Access
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Solution Overview
Problem
The manufacturing process of STT-MRAM is complicated due to the need for repeated film formation of MTJ elements with different insulating layer thicknesses, leading to increased manufacturing steps and reduced yield due to ion beam etching issues and redeposit formation.
Innovation Solution
A storage device with an underlayer having an inclined surface on which storage elements are arranged, allowing simultaneous formation of MTJ elements with different insulating layer thicknesses, reducing manufacturing complexity and improving yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If MTJ elements with different insulating layer thicknesses are formed by repeated film formation, then storage elements with different thermal stability can be achieved, but the number of manufacturing steps increases and the manufacturing process becomes complicated
Solution Approach 1:
The patent introduces an inclined surface (tilted surface) on the underlayer as a new geometric dimension. By forming storage elements at different positions along this inclined surface, elements with different insulating layer thicknesses are obtained in a single film formation process, eliminating the need for repeated deposition steps and resolving the contradiction between versatility and manufacturing complexity.
2Area of moving object
If MTJ elements are arranged on the same plane with narrow element intervals, then integration density is improved, but ion beam may be blocked during etching and redeposit causes short-circuited elements reducing yield
Solution Approach 1:
The patent arranges storage elements along an inclined surface rather than on a flat plane. This spatial reconfiguration in a third dimension allows ion beam to access etching surfaces without being blocked by adjacent elements, enabling effective redeposit removal while maintaining narrow element intervals and high integration density.
Solution Approach 2:
The inclined surface creates asymmetric spatial relationships between adjacent storage elements. This asymmetry ensures that the ion beam path to each element's etching surface is unobstructed, preventing the blocking issue that occurs in symmetric planar arrangements where elements mutually shadow each other during etching.
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 improves productivity by simplifying the manufacturing process while maintaining the effectiveness and efficiency of the storage device, thereby enhancing the productivity and reducing manufacturing defects.
Implementation Method 1
an insulating layer (e.g., MgO) sandwiched between the magnetic layers
Implementation Method 2
ion beam in ion beam etching (IBE) processing may be blocked by one element nearby
Implementation Method 3
an MRAM that reverses the magnetization of the magnetic substance using spin torque magnetization reversal
Implementation Method 4
the MTJ element is also referred to as a tunneling magneto resistive (TMR) element
Data Source
AI summary
A storage device according to an aspect of the present disclosure includes a plurality of storage elements (e.g., MTJ element) each including a fixed layer with a fixed magnetization direction, a storage layer with a changeable magnetization direction, and an insulating layer provided between the fixed layer and the storage layer, an underlayer (e.g., lower insulating layer) on which the plurality of storage elements is provided in an array, and a semiconductor substrate having a surface on which the underlayer is laminated. The underlayer has an inclined surface inclined with respect to the surface, and any of the plurality of storage elements is provided on the inclined surface.