Bulk Acoustic Wave Resonator Bonding Pad Recess for Delamination Control
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Solution Overview
Problem
Traditional bulk acoustic wave resonators face issues with poor adhesion between the bonding layer and components, leading to potential delamination and reliability problems such as frequency deviation and bump fracture due to deformation of the bonding layer.
Innovation Solution
The design includes a resonant body structure with conductive connectors positioned on opposite sides of the piezoelectric layer, utilizing a recessed bonding pad structure and a cover bonding layer that fills the recess, enhancing the bonding area and minimizing the impact of potential deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a bonding layer is used to bond the cover structure with the piezoelectric layer, then the cover structure can be attached to the resonator, but the adhesion between the bonding layer and components may be poor leading to delamination
Solution Approach 1:
The recess is formed in the bonding pad before the bonding process, and the cover bonding layer is designed to protrude into this recess. This preliminary structural preparation ensures that when bonding occurs, the cover bonding layer is mechanically interlocked with the bonding pad, preventing delamination caused by subsequent deformation or thermal stress.
Solution Approach 2:
The bonding interface is enhanced locally by creating a recess specifically at the bonding pad area where the cover bonding layer makes contact. This local structural modification increases the bonding area and creates a mechanical interlock, while the rest of the device structure remains unchanged.
2Strength
If the bonding layer is made thicker to improve bonding strength, then adhesion may improve, but the bonding layer undergoes deformation such as expansion or contraction leading to delamination
Solution Approach 1:
The invention changes the geometric parameters of the bonding interface by creating a recess with specific dimensions. The protrusion of the cover bonding layer into this recess creates a mechanical interlock that compensates for thermal expansion and contraction, maintaining bonding stability despite temperature variations during device operation.
Solution Approach 2:
The recess structure acts as a cushioning mechanism that absorbs the stress from thermal expansion and contraction of the bonding layer. By preparing this structural feature in advance, the design prevents delamination that would otherwise occur during temperature cycling, without requiring the bonding layer to be thinner.
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 configuration maintains effective electrical connections and improves the reliability of the resonator by reducing the risk of delamination and increasing bonding strength, thus enhancing device performance.
Implementation Method 1
a piezoelectric layer, a first electrode structure layer and a second electrode layer, wherein the piezoelectric layer has a first side and a second side opposite to each other
Data Source
AI summary
A bulk acoustic wave resonator and manufacturing method thereof and filter, the bulk acoustic wave resonator includes: a resonant body structure, and a carrier structure and a cover structure on two opposite sides of the resonant body structure; a first cavity is between the carrier structure and the resonant body structure; the cover structure includes a cover substrate, and a cover bonding layer, a second cavity is between the cover structure and the resonant body structure; first and second conductive connectors, and a pad layer are on opposite sides of the resonant body structure, and the pad layer includes one or more bonding pads bonded with the cover bonding layer, each bonding pad has a recess recessed toward the resonant body structure, and the cover bonding layer includes a protrusion part filling the recess and surrounded by the bonding pad.