Wafer-Level Ferrimagnetic Resonator Fabrication

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing methods for manufacturing YIG resonators are cumbersome, requiring specialized tools and skilled operators, resulting in bulky and expensive components, and are limited to single resonator production at a time.

Innovation Solution

A wafer-level fabrication process involving isotropic cavity etching, metallization, wafer bonding, glass blowing, and self-assembly of YIG spheres, allowing for the simultaneous production of hundreds of YIG resonators in parallel.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional boutique manufacturing processes are used for YIG resonators, then manufacturing precision can be achieved through skilled operator positioning, but device complexity increases and productivity decreases due to single-unit production requirements

Engineering Contradiction:

Improvepositioning precisionVSAvoidproduction rate

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The manufacturing process is segmented into discrete wafer-level steps (etching, metallization, bonding, glass blowing) that can be automated and performed in parallel across multiple resonators simultaneously, transitioning from single-unit boutique manufacturing to high-volume production

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Manual mechanical positioning by skilled operators is replaced with automated wafer-level fabrication processes including photolithographic patterning, plasma etching, and thermal field annealing that provide precise control without requiring human intervention for each component

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If conventional single-resonator manufacturing methods are used, then specialized tools can provide precise alignment, but manufacturing time increases and costs increase

Engineering Contradiction:

Improvealignment precisionVSAvoidmanufacturing time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

Multiple resonator fabrication operations are merged into a single wafer-level process flow where hundreds of resonators are fabricated simultaneously through parallel etching, metallization, and bonding operations, dramatically reducing total manufacturing time

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

Alignment references and structural features are pre-formed during wafer fabrication before resonator assembly, eliminating the need for time-consuming post-fabrication alignment operations and specialized alignment tools

Inventive Principle:

Principle #10Preliminary action

3Reliability

If small coupling loops are used tightly coupled to the YIG sphere, then self-resonances are minimized and frequency range improves, but manufacturing complexity increases

Engineering Contradiction:

Improveresonance performanceVSAvoidcoupling loop structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The wafer-level fabrication process provides universal capabilities for forming different coupling loop geometries and configurations through standardized photolithographic and metallization steps, allowing optimization for specific frequency ranges without requiring complex specialized manufacturing procedures

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 process reduces manufacturing time and costs, enables the production of small form factor resonators, and minimizes self-resonances by using small coupling loops tightly coupled to the YIG sphere.

Implementation Method 1

isotropic cavity etching includes wet etching at least one cavity in the cap wafer and at least one hole for a coil trace and at least on electrode pad in the inner wafer

Methodology Applied

Scientific EffectWet etching:

Implementation Method 2

wafer bonding of the at least one glass wafer with a silicon wafer to form a bonded wafer

Methodology Applied

Scientific EffectWafer bonding:

Implementation Method 3

controlling, by the device, glass blowing of the bonded wafer to form a dual hemisphere structure

Methodology Applied

Scientific EffectGlass blowing:

Implementation Method 4

controlling, by the device, etching of the bonded wafer to form at least one nest for a sphere element

Methodology Applied

Scientific EffectEtching:

Data Source

PatentUS20250136441A1Wafer-level fabrication processes for ferrimagnetic resonators and resonator devices

Publication Date: 2025.05.01 RGT UNIV OF CALIFORNIA

AI summary

Systems, processes and devices are provided for wafer-level fabrication of a resonator. A process is provided that includes chemical etching of glass and silicon, high-temperature glassblowing, controlling assembly of at least one YIG sphere relative to a nest structure, and plasma assisted wafer bonding. The process can include formation of loop coils and spherical coils defined by the glassblowing process including inner and outer hemispherical structures. The inner hemispherical structure may provide loops to drive and detect resonance in YIG spheres. Processes discussed herein allow for placement of loops in close proximity (e.g., few microns) to ferrimagnetic elements. The outer hemisphere may provide harmonic magnetic coils for frequency tuning. Embodiments are also directed to a resonator including first and second wafer-level glass blown wafer stacks each with inner hemisphere and outer hemispheres. The resonator includes coupling loop coils, tuning coils, and a sphere element nested between glass blown wafer stacks.