MRAM Alignment via Trench Structures

Solution Overview

Problem

The manufacturing of magnetoresistive random access memory (MRAM) devices faces challenges in achieving alignment accuracy between the magnetic tunnel junction (MTJ) and interconnecting structures as the cell size decreases, leading to insufficient contacting areas and high series resistance.

Innovation Solution

A semiconductor structure and method involving a substrate with a device region and alignment mark region, a dielectric layer, conductive via, and memory stack structure, where a first trench and second trenches are formed to improve alignment accuracy, allowing the memory stack to fill into these trenches and ensure precise alignment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the cell size of the MRAM is reduced to achieve higher density, then the storage density is improved, but the alignment accuracy between the MTJ and interconnecting structures deteriorates

Engineering Contradiction:

Improvestorage densityVSAvoidalignment accuracy

Core Design Contradiction:

Quantity of substanceVSManufacturing precision

Solution Approach 1:

The patent forms alignment marks and etch trenches in the interconnecting structures before forming the MTJ. The MTJ is then formed to precisely align with these pre-established alignment marks and trenches, ensuring accurate positioning even in high-density configurations where alignment is more critical.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces alignment marks as intermediary features between the interconnecting structures and the MTJ. These alignment marks serve as reference points that facilitate precise alignment during the formation process, acting as a mediator that bridges the positioning requirements of both structures.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If the alignment accuracy between MTJ and interconnecting structures is insufficient, then the manufacturing process is simplified, but the contacting area between bottom electrode and interconnecting structure is reduced

Engineering Contradiction:

Improvemanufacturing process simplicityVSAvoidcontacting area

Core Design Contradiction:

Ease of manufactureVSArea of stationary object

Solution Approach 1:

The patent forms alignment marks and etch trenches in the interconnecting structures before forming the MTJ. The MTJ is then formed to precisely align with these pre-established alignment marks and trenches, ensuring accurate positioning even in high-density configurations where alignment is more critical.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces alignment marks as intermediary features between the interconnecting structures and the MTJ. These alignment marks serve as reference points that facilitate precise alignment during the formation process, acting as a mediator that bridges the positioning requirements of both structures.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Device complexity

If the alignment accuracy is insufficient, then the manufacturing process is less complex, but the series resistance increases

Engineering Contradiction:

Improvemanufacturing process complexityVSAvoidseries resistance

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent forms alignment marks and etch trenches in the interconnecting structures before forming the MTJ. The MTJ is then formed to precisely align with these pre-established alignment marks and trenches, ensuring accurate positioning even in high-density configurations where alignment is more critical.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces alignment marks as intermediary features between the interconnecting structures and the MTJ. These alignment marks serve as reference points that facilitate precise alignment during the formation process, acting as a mediator that bridges the positioning requirements of both structures.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS10937946B2Semiconductor structure and method for forming the same

Publication Date: 2021.03.02 UNITED MICROELECTRONICS CORP

AI summary

A semiconductor structure is provided in the present invention, including a substrate having a device region and an alignment mark region defined thereon, a dielectric layer disposed on the substrate, a conductive via formed in the dielectric layer on the device region, a first trench formed in the dielectric layer on the alignment mark, a plurality of second trenches formed in the dielectric layer directly under the first trench and exposed from a bottom surface of the first trench, and a memory stacked structure disposed on the dielectric layer, directly covering a top surface of the conductive via and filling into the first trench and the second trench.