MTJ Patterning via Metal Mask to Prevent Carbon Collapse
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Solution Overview
Problem
The fabrication of magnetic tunnel junction (MTJ) elements in semiconductor devices is challenging due to difficulties in patterning thin and small carbon layers, which can collapse or slant, affecting the reliability of the metal pattern and ultimately the MTJ element formation.
Innovation Solution
A method involving the formation of a carbon layer with a hole, where a metal pattern is created within the hole, and this metal pattern is used as an etching mask to pattern the MTJ layers, thereby avoiding the need for patterning the carbon layer directly and preventing collapse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a carbon layer is patterned directly to form metal patterns, then the metal pattern can be formed, but the carbon layer collapses or slants affecting reliability
Solution Approach 1:
The patent introduces a metal layer as an intermediary between the carbon layer and the final metal pattern. The metal layer is formed first, then patterned to create the metal pattern, which serves as a stable mask for subsequent MTJ layer patterning. This intermediary metal pattern avoids the collapse issue of directly patterning the thin carbon layer while maintaining manufacturing precision.
2Length of moving object
If the carbon layer is made thin to achieve smaller patterns, then pattern size can be reduced below 30 nm, but the carbon layer becomes unstable and collapses
Solution Approach 1:
The patent changes the material parameter from carbon to metal for the pattern-forming layer. By forming the pattern in a metal layer instead of a carbon layer, the structural stability is dramatically improved while enabling smaller pattern sizes below 30 nm. The metal layer provides the mechanical strength needed to maintain thin feature dimensions without collapse.
3Ease of manufacture
If semiconductor process machines are used to pattern ferromagnetic and insulating layers, then fabrication can be performed, but the machines are not advanced enough for required precision
Solution Approach 1:
The patent creates a metal pattern that copies the desired final MTJ element pattern. This metal pattern serves as a reusable mask that defines the precise geometry for patterning the ferromagnetic and insulating layers. By copying the pattern into a metal layer first, the precision requirements are met using standard semiconductor patterning equipment without needing advanced machines.
Data Source
AI summary
A method for fabricating a semiconductor device includes forming a metal layer on a substrate, forming a plurality of layers of a magnetic tunnel junction (MTJ) element on the metal layer, forming a carbon layer including a hole, wherein the hole penetrates through the carbon layer, forming a metal pattern in the hole of the carbon layer, removing the carbon layer; and patterning the plurality of layers of the MTJ element using the metal pattern as an etching mask.