Embedded SAW Electrode Layout for Coplanar Hybrid Bonding
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Solution Overview
Problem
Existing SAW devices face challenges in miniaturization and integration with ASIC chips due to the protrusion of electrodes above the piezoelectric layer, hindering effective integration into hybrid bonding packages.
Innovation Solution
A method involving the formation of recesses in the dielectric and piezoelectric layers to embed electrodes, ensuring coplanarity with the top surfaces of the dielectric or piezoelectric layers, followed by metal deposition and planarization processes to facilitate hybrid bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If electrodes are formed on the piezoelectric layer using conventional methods, then the SAW device can be fabricated, but the electrodes protrude above the piezoelectric layer which hinders integration with ASIC chips in hybrid bonding packages
Solution Approach 1:
The electrode is embedded within recesses formed in the piezoelectric layer and overlying dielectric layers, creating a nested structure where the electrode is contained within the layered architecture rather than protruding outward. This nesting approach enables coplanar surfaces that facilitate hybrid bonding integration with ASIC chips.
Solution Approach 2:
The invention transitions from a planar electrode configuration to a three-dimensional embedded structure by forming recesses in multiple layers. This dimensional change allows the electrode to be positioned within the depth of the layered structure, creating coplanar top surfaces that resolve the protrusion issue while maintaining electrical functionality.
2Volume of moving object
If the device size is reduced for miniaturization, then space efficiency improves, but integration challenges increase due to electrode protrusion
Solution Approach 1:
By nesting the electrode within recesses of the piezoelectric and dielectric layers, the overall device profile is reduced. The embedded configuration eliminates protruding elements that would increase device volume, enabling miniaturization while maintaining integration compatibility with hybrid bonding packages.
Solution Approach 2:
The electrode is positioned in the vertical dimension within recesses rather than extending horizontally, allowing the device footprint to be minimized. This three-dimensional arrangement enables compact device sizing while preserving the coplanar surfaces necessary for hybrid bonding integration.
3Productivity
If coplanar surfaces are achieved for hybrid bonding, then integration efficiency improves, but additional fabrication steps are required
Solution Approach 1:
The recesses are formed in the piezoelectric and dielectric layers before the electrode is deposited. This preliminary action of creating the recess structures in advance allows the electrode to be subsequently embedded and planarized in a streamlined sequence, improving integration efficiency while managing fabrication complexity through logical process sequencing.
Solution Approach 2:
The formation of recesses in both the piezoelectric layer and overlying dielectric layers is combined into a coordinated fabrication sequence, where the electrode embedding and planarization steps are merged to achieve coplanar surfaces. This consolidation of steps optimizes the fabrication process for hybrid bonding integration.
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
Enables efficient integration of SAW devices with ASIC chips by reducing the overall device size and enhancing performance through hybrid bonding, thereby meeting the demands of miniaturization in mobile communication devices.
Implementation Method 1
performing a photo-etching process to remove the second dielectric layer for forming a recess in the second dielectric layer
Implementation Method 2
SAW device are made of piezoelectric materials such as lithium niobate (LiNbO3) or lithium tantalite (LiTaO3) and since these materials have larger electromechanical coupling coefficient
Data Source
AI summary
A method for fabricating a surface acoustic wave (SAW) device includes the steps of forming a first dielectric layer on a substrate, forming a piezoelectric layer on the first dielectric layer, forming a second dielectric layer on the piezoelectric layer, performing a photo-etching process to remove the second dielectric layer for forming a recess in the second dielectric layer, forming a metal layer in the recess, and then performing a planarizing process to remove the metal layer for forming an electrode in the recess.