Zigzag Magnetic Stack Inductor via 2P2E Process

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Solution Overview

Problem

Conventional inductor structures in semiconductor devices face challenges due to the conventional one-photo-one-etch (1P1E) process, which results in a small magnetic stack volume and decreased performance, including a lower Q factor, as the etching time required to define the magnetic stack is lengthy, leading to volume loss and reduced performance.

Innovation Solution

The implementation of a two-photo-two-etch (2P2E) process to form a magnetic stack with a zigzag shaped stepped profile, where a first and second photolithography step are used to etch the magnetic stack, forming a first and second stepped structure, respectively, with a polymer layer encapsulating the magnetic stack, thereby increasing the magnetic stack volume and improving performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a one-photo-one-etch (1P1E) process is used to form the magnetic stack, then the manufacturing process is simpler, but the magnetic stack volume is reduced and performance deteriorates

Engineering Contradiction:

Improvemanufacturing process simplicityVSAvoidmagnetic stack volume

Core Design Contradiction:

Ease of manufactureVSVolume of stationary object

Solution Approach 1:

The patent divides the single etching operation into two separate etching steps (first etch and second etch) with distinct photoresist patterns. The first etch creates an initial magnetic stack structure, and the second etch refines the shape to achieve the desired zigzag stepped profile. This segmentation allows for better control of the magnetic stack volume and shape while maintaining manufacturing feasibility through systematic process breakdown.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first photolithography and etching step performs preliminary formation of the magnetic stack structure before the second refinement step. This preliminary action establishes the base magnetic stack volume that is then optimized in the second step, ensuring sufficient volume is maintained throughout the process while achieving the final precise geometry.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If a one-photo-one-etch (1P1E) process is used, then the manufacturing steps are fewer, but the etching time is lengthy and performance decreases

Engineering Contradiction:

Improvemanufacturing efficiencyVSAvoidinductor performance

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

By segmenting the etching process into two controlled steps, each etching operation can be optimized for shorter duration while achieving the cumulative effect of the final magnetic stack shape. This reduces the total etching time compared to a single lengthy etch while improving performance through better volume control.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The process uses periodic alternating actions of photoresist deposition and etching (first photo/first etch, second photo/second etch) to progressively shape the magnetic stack. This periodic approach allows for controlled material removal in stages, reducing total processing time while maintaining precision and performance.

Inventive Principle:

Principle #19Periodic action

3Device complexity

If a conventional etching process is used, then the process is simpler, but volume loss occurs and Q factor is reduced

Engineering Contradiction:

Improveprocess complexityVSAvoidmagnetic stack volume loss

Core Design Contradiction:

Device complexityVSLoss of substance

Solution Approach 1:

The segmented two-step etching process allows for controlled material removal where each step removes only the necessary amount to achieve the zigzag stepped profile. This prevents excessive volume loss that would occur in a single aggressive etching step, maintaining magnetic stack volume while achieving the required geometry.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Each etching step performs a partial action rather than attempting complete shaping in one step. The first etch performs partial shaping and the second etch completes the zigzag profile, ensuring that material removal is minimized and controlled, thereby reducing volume loss while achieving the precise final shape.

Inventive Principle:

Principle #16Partial or excessive action

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 2P2E process minimizes volume loss and enhances the performance of the inductor structure by maintaining a larger magnetic stack volume, resulting in a higher Q factor and improved inductor performance.

Implementation Method 1

a first photolithography step is performed to form a first photoresist layer on the magnetic stack. A first etching step is performed to an upper portion of the magnetic stack by using the first photoresist layer as an etch mask

Methodology Applied

Scientific EffectPhotolithography: Photopolymerisation

Data Source

PatentUS10263064B2Semiconductor devices and methods of forming the same

Publication Date: 2019.04.16 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

Semiconductor devices and methods of forming the same are disclosed. One of the semiconductor device includes an inductor structure, and the inductor structure is on a substrate and includes a first metal layer, a magnetic stack, a polymer layer and a second metal layer. The first metal layer is over the substrate. The magnetic stack is over the first metal layer and has a substantially zigzag shaped sidewall. The polymer layer is over the first metal layer and encapsulates the magnetic stack. The second metal layer is over the polymer layer.