FBAR Filter Electrode Trimming for Wafer RF Consistency
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Solution Overview
Problem
The fabrication of film bulk acoustic resonator (FBAR) filter devices faces challenges in achieving consistent electrical characteristics across a wafer due to variations in electrode thickness, leading to poor performance consistency and reduced wafer yield.
Innovation Solution
A method is introduced to adjust the thickness of electrodes or passivation layers in FBAR filter devices based on radio frequency (RF) performance tests, allowing for precise adjustments in different areas of the wafer to enhance consistency and yield, using techniques like ion beam trimming to achieve targeted thicknesses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a plurality of FBAR filter devices are fabricated on a wafer using semiconductor micro-processing technology, then productivity is improved, but manufacturing precision deteriorates due to variations in electrode thickness across the wafer
Solution Approach 1:
The patent applies preliminary action by forming a first passivation layer on the first electrode before forming the second electrode, and then performing RF performance tests to determine the thickness of the second electrode or second passivation layer. This preliminary structuring enables subsequent selective thinning or removal to achieve precise thickness control for each resonator, resolving the contradiction between batch fabrication productivity and individual device precision.
Solution Approach 2:
The patent implements local quality by allowing different resonators on the same wafer to have different electrode or passivation layer thicknesses based on their specific RF performance requirements. Through selective thinning or removal of the second electrode or second passivation layer, each resonator can be individually optimized while maintaining batch fabrication efficiency, thus achieving both high productivity and manufacturing precision.
2Manufacturing precision
If the thickness of electrodes is adjusted to improve RF performance, then manufacturing precision is improved, but device complexity increases due to additional process steps
Solution Approach 1:
The patent uses preliminary action by pre-forming the first passivation layer and second electrode with initial thicknesses that accommodate subsequent adjustment steps. This preliminary structuring allows for controlled thinning or removal operations to achieve precise final thicknesses, managing the added process complexity through systematic preparation.
Solution Approach 2:
The patent applies parameter changes by adjusting the thickness of the second electrode or second passivation layer based on RF performance test results. Through controlled thinning or removal processes, the physical parameter of layer thickness is modified to optimize performance, transforming the fabrication process from fixed-thickness to adjustable-thickness to resolve the contradiction between precision and complexity.
3Ease of manufacture
If uniform thickness is applied to all electrodes on a wafer, then ease of manufacture is improved, but performance consistency deteriorates across different areas of the wafer
Solution Approach 1:
The patent implements local quality by enabling different resonators on the same wafer to have different second electrode or second passivation layer thicknesses tailored to their specific locations and performance requirements. This approach maintains ease of manufacture through batch processing while achieving performance consistency across the wafer by allowing local variations in the final thickness parameters.
Solution Approach 2:
The patent uses preliminary action by forming uniform first passivation layers and second electrodes across the entire wafer before performing selective thinning or removal operations. This preliminary uniform fabrication maintains ease of manufacture, while subsequent localized adjustments achieve the necessary performance consistency across different wafer areas.
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 improves the performance consistency of FBAR filter devices across the entire wafer by allowing for tailored thickness adjustments, thereby increasing the yield and ensuring better electrical characteristics.
Implementation Method 1
using techniques like ion beam trimming to achieve targeted thicknesses
Data Source
AI summary
A method for fabricating a film bulk acoustic resonator (FBAR) filter device is provided. The method includes: forming a first electrode of each one of a first resonator and a second resonator on a first surface of a piezoelectric layer, forming a first passivation layer of each one of the first resonator and the second resonator on a corresponding one of the first electrodes, forming a second electrode of each one of the first resonator and the second resonator on a second surface of the piezoelectric layer, conducting a radio frequency (RF) performance test on the FBAR filter device, adjusting a thickness of the second electrode of the first resonator based on a result of the RF performance test, and forming a second passivation layer of each one of the first resonator and the second resonator on a corresponding one of the second electrodes.