MTJ Top Electrode Smoothing for Flatness Under High-Grain Deposition
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Solution Overview
Problem
High grain size in top electrode films of magnetic tunnel junction (MTJ) memory cells leads to the formation of spike point defects, which impede device performance due to high temperature and long plasma deposition times during fabrication.
Innovation Solution
Implementing plasma treatments and soaking treatments, along with depositing conductive layers using multiple steps with low and high bias power, to smooth the surface and reduce spike points in the top electrode films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high temperature and long plasma deposition times are used during fabrication, then complete deposition of top electrode films is achieved, but high grain size forms leading to spike point defects
Solution Approach 1:
A nitrogen soak treatment is performed before the plasma deposition process. This preliminary action prepares the substrate surface by saturating it with nitrogen, which prevents excessive grain growth during subsequent high-temperature deposition, thereby preventing spike point defects before they can form
Solution Approach 2:
The deposition process is divided into multiple stages with different plasma power levels (high power for initial deposition, low power for final layers). This parameter change allows control over grain size development throughout the deposition process, achieving complete deposition while maintaining surface flatness
2Quantity of substance
If plasma deposition is performed to form top electrode films, then conductive layers are deposited, but spike point defects form on the film surface
Solution Approach 1:
The top electrode film deposition is segmented into multiple stages: initial high-power plasma deposition for bulk material accumulation, followed by low-power plasma deposition for final layers. This segmentation allows the film to achieve sufficient thickness while the reduced power in later stages prevents excessive grain growth and surface roughening
Solution Approach 2:
Plasma power parameters are changed between deposition stages. High power is used initially to achieve adequate film thickness quickly, then power is reduced for subsequent layers to control grain size and maintain surface flatness, preventing spike point defects
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
The proposed method effectively reduces spike point defects, enhancing the flatness and performance of top electrode films, thereby improving the overall performance of MTJ memory cells.
Implementation Method 1
performing a smoothing treatment on the first TE layer, wherein the smoothing treatment is performed in situ with the forming the first TE layer
Implementation Method 2
depositing conductive layers using multiple steps with low and high bias power
Implementation Method 3
The PVD process or the CVD process may be accompanied by the generation of plasma
Data Source
AI summary
A method of forming a semiconductor structure includes forming a first top electrode (TE) layer over a magnetic tunnel junction (MTJ) layer and performing a smoothing treatment on the first TE layer. The smoothing treatment is performed in situ after the forming first TE layer. The smoothing treatment removes spike point defects from the first TE layer. Additional TE layers may be formed over the first TE layer.