Magnetic Inductor Stress Control via Laminated Film Stacks
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The deposition of thicker magnetic materials for on-chip inductors leads to tensile stress, causing wafer bowing, which complicates lithography alignment and wafer chucking in processing tools, as the stress exceeds 50 to 400 MPa and results in significant bowing when the cumulative thickness exceeds 1 micron.
Innovation Solution
The implementation of laminated film stacks with alternating layers of magnetic and insulating materials, separated by spaces and isolated with a conformal dielectric layer, to relieve stress and prevent wafer bowing, allowing for cumulative magnetic layer thicknesses greater than 1 micron without significant distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If thicker magnetic materials are deposited to achieve high energy density, then energy storage capability is improved, but tensile stress increases causing wafer bowing
Solution Approach 1:
The patent divides the thick magnetic material into multiple thin magnetic layers separated by insulating layers. This segmentation reduces the cumulative tensile stress while maintaining the total magnetic thickness required for high energy storage. Each thin magnetic layer has reduced stress compared to a single thick layer, and the insulating layers provide stress relief and electrical isolation.
Solution Approach 2:
The patent creates a composite structure alternating between magnetic materials and insulating materials. This composite approach allows the magnetic layers to achieve the required cumulative thickness for energy storage while the insulating layers counterbalance the tensile stress and prevent wafer bowing.
2Use of energy by moving object
If thicker magnetic materials are deposited to achieve high energy density, then energy storage capability is improved, but wafer bowing increases causing lithography alignment issues
Solution Approach 1:
By segmenting the thick magnetic material into multiple thin layers separated by insulating materials, the patent reduces wafer bowing to less than 75 nm. This segmentation maintains the total magnetic thickness for energy storage while keeping the wafer flat enough for lithography alignment and processing tool operation.
Solution Approach 2:
The patent changes the structural parameters by introducing alternating magnetic and insulating layers with specific thickness ratios. This parameter change transforms the stress distribution, reducing wafer bowing from significant distortion to less than 75 nm, thereby enabling use of state-of-the-art lithography tools.
3Use of energy by moving object
If thicker magnetic materials are deposited to achieve high energy density, then energy storage capability is improved, but wafer bowing increases causing processing difficulties
Solution Approach 1:
The patent segments the magnetic material structure into multiple thin layers with insulating layers in between, which reduces wafer bowing and enables easy processing. The segmented structure allows standard lithography and processing tools to operate effectively while maintaining the cumulative magnetic thickness needed for high energy storage.
Solution Approach 2:
The insulating layers act as intermediary elements between the magnetic layers, providing stress relief and facilitating easy processing. These intermediary layers reduce wafer bowing to acceptable levels, enabling the use of conventional processing tools without modification.
4Stress or pressure
If laminated film stacks with spaces and dielectric isolation layers are implemented, then wafer bowing is reduced, but device complexity increases
Solution Approach 1:
The patent uses segmentation of magnetic and insulating layers, which reduces wafer bowing through a relatively simple repeating pattern. This segmented structure achieves stress relief without requiring complex additional components, as the insulating layers are integrated into the existing magnetic layer stack.
Solution Approach 2:
The patent merges multiple functions into the insulating layers: they provide electrical isolation between magnetic layers, stress relief to reduce wafer bowing, and structural support. This merging reduces the need for separate components, thereby limiting the increase in device complexity while achieving significant bowing reduction.
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 wafer bowing to less than 75 nm, enabling the use of state-of-the-art lithography and processing tools by iteratively patterning and depositing magnetic layers with dielectric spacers, maintaining a flat wafer surface and achieving high performance inductors with cumulative magnetic thicknesses up to several microns.
Implementation Method 1
at least one dielectric isolation layer conformally deposited onto and within the film stacks having a thickness effective to electrically isolate the film stacks from one another
Implementation Method 2
laminated film stacks separated by a space, each film stack comprising alternating layers of magnetic materials and insulating materials
Data Source
AI summary
A magnetic laminating structure and process for preventing substrate bowing include multiple film stack segments that include a first magnetic layer, at least one additional magnetic layer, and a dielectric spacer disposed between the first and at least one additional magnetic layers. A dielectric isolation layer is intermediate magnetic layers and on the sidewalls thereof. The magnetic layers are characterized by defined tensile strength and the multiple segments function to relive the stress as the magnetic laminating structure is formed, wherein the cumulative thickness of the magnetic layers is greater than 1 micron. Also described are methods for forming the magnetic laminating structure.