Semiconductor Structure Top Electrode Oxidation Control

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The existing semiconductor technologies face a challenge in reducing series resistance in magnetic tunneling junction (MTJ) devices due to non-conductive oxide layers, which are difficult to remove without damaging adjacent metal line layers during the fabrication of embedded MRAM cells in CMOS structures.

Innovation Solution

The use of a top electrode material with a lower oxidation rate, such as TiN, reduces the formation of oxide layers, eliminating the need for post-deposition bombardment and thereby minimizing series resistance without harming the logic region's metal line layers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If post-deposition bombardment is used to remove oxide layers, then series resistance is reduced, but adjacent metal line layers are damaged

Engineering Contradiction:

Improveseries resistanceVSAvoiddamage to metal line layers

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent uses the oxidation property that previously caused harm (oxide layer formation increasing series resistance) and converts it into a benefit by selecting a top electrode material (TiN) with controlled oxidation characteristics that forms minimal oxide, thereby reducing series resistance without requiring harmful bombardment processes

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent changes the material parameter of the top electrode from conventional materials to TiN, which has a lower oxidation rate. This parameter change fundamentally alters the oxidation behavior, reducing oxide layer formation and eliminating the need for post-deposition bombardment to reduce series resistance

Inventive Principle:

Principle #35Parameter changes

2Reliability

If TiN is used as top electrode material, then oxide layer formation is reduced, but material selection constraints increase

Engineering Contradiction:

Improveoxide layer formationVSAvoidmaterial selection

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent specifies a particular material parameter (oxidation rate) and selects TiN that satisfies the condition of having a lower oxidation rate than conventional materials. This parameter-based selection approach provides clear design criteria while achieving the desired reduction in oxide layer formation

Inventive Principle:

Principle #35Parameter changes

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 effectively reduces series resistance in MTJ devices by minimizing oxide layer formation, ensuring the integrity of both the MRAM cell and logic region metal line layers during fabrication.

Implementation Method 1

The top electrode includes material having an oxidation rate lower than that of Tantalum or Tantalum derivatives

Methodology Applied

Scientific EffectOxidation: Oxidation

Data Source

PatentUS11227893B2Semiconductor structure and method of forming the same

Publication Date: 2022.01.18 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

The present disclosure provides a semiconductor structure, including a logic region and a memory region adjacent to the logic region. The memory region includes a Nth metal layer, a bottom electrode over the Nth metal layer, a magnetic tunneling junction (MTJ) layer over the bottom electrode, a top electrode over the MTJ layer, and a (N+1)th metal layer over the top electrode. The top electrode includes material having an oxidation rate lower than that of Tantalum or Tantalum derivatives. N is an integer greater than or equal to 1.