Planarization Method for Cavity Filters
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Solution Overview
Problem
Conventional CMP processes are complex, costly, and unsuitable for materials like aluminum nitride, and they planarize the entire product surface, which limits their applicability and efficiency.
Innovation Solution
A planarization method involving the deposition and etching of passivation layers, specifically using aluminum nitride, to achieve partial planarization of a product with a cavity and inclined surfaces, allowing for better control and simplicity in the process, particularly suitable for filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If CMP process is used for planarization, then planarization can be achieved, but the process becomes complicated and cost increases
Solution Approach 1:
The patent divides the planarization process into multiple etching steps with different etching solutions applied to different regions. The first etching solution is applied to the first region, then a second etching solution to the second region, achieving selective planarization without requiring a complex CMP process.
Solution Approach 2:
The patent applies different etching solutions to different regions of the substrate based on local material composition. The first etching solution targets materials in the first region, while the second etching solution targets materials in the second region, enabling localized planarization tailored to specific material areas.
2Manufacturing precision
If CMP process is used for planarization, then planarization can be achieved, but material compatibility is limited
Solution Approach 1:
The patent uses different etching solutions for different material regions. The first etching solution is selective to materials in the first region, while the second etching solution is selective to materials in the second region, allowing the process to handle diverse materials like aluminum nitride and silicon nitride that are incompatible with CMP.
Solution Approach 2:
The patent changes the chemical parameters by using different etching solutions with different chemistries. This allows selective removal of different materials based on their chemical properties rather than mechanical properties, expanding material compatibility beyond what CMP can handle.
3Manufacturing precision
If whole product is planarized by CMP, then uniform planarization is achieved, but process efficiency decreases
Solution Approach 1:
The patent segments the substrate into multiple regions with different planarization requirements and applies different etching solutions to each region. This allows simultaneous treatment of different areas with appropriate chemistry, improving overall process efficiency while maintaining the planarization quality needed for each specific region.
Solution Approach 2:
The patent applies etching selectively only to regions where planarization is needed, rather than treating the entire substrate uniformly. This partial action approach improves efficiency by avoiding unnecessary processing of areas that already have acceptable surface quality or require different treatment.
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 method simplifies the planarization process, enhances control, and is applicable to a wider range of materials, achieving better local planarization and uniformity compared to traditional CMP methods.
Implementation Method 1
the first passivation layer is etched to form a lining pad by the first passivation layer on the periphery of the third inclined surface part
Implementation Method 2
a second passivation layer is deposited on the second electrode layer and covers the second electrode layer, the lining pad and the piezoelectric layer
Implementation Method 3
carrying out the totally etching on the second passivation layer until the thickness of the second passivation layer is reduced to the required thickness; and releasing the oxide in the cavity for obtaining a finished product
Data Source
AI summary
The invention provides a planarization method, which can make the local flatness of the product to be processed more uniform. The product has a cavity filled with oxide and includes a first electrode layer, a piezoelectric layer and a second electrode layer superposed on the cavity. The first electrode layer covers the cavity and includes a first inclined face around the first electrode layer, and the piezoelectric layer covers the first electrode layer and is arranged on the first electrode layer. The planarization method includes: depositing a passivation layer on the second electrode layer and etching the passivation layer completely until the thickness of the passivation layer is reduced to the required thickness.