Planarization Method Using Passivation Layer Etching
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Solution Overview
Problem
Conventional CMP processes are complex, costly, and limited in material suitability, particularly for materials like aluminum nitride and silicon nitride, and they planarize the entire product surface rather than allowing for localized adjustments.
Innovation Solution
A planarization method involving the deposition of a passivation layer with specific inclined surface features, followed by total etching to achieve partial planarization, using aluminum nitride for the passivation layer, which allows for better control and applicability to materials like aluminum nitride and silicon nitride, and includes a seed layer between electrode layers.
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 replaces the mechanical CMP (chemical mechanical polishing) process with a deposition-etching process. Instead of mechanically polishing the surface, the invention deposits a passivation layer conformally and then performs isotropic etching to achieve planarization. This substitution eliminates the complexity of CMP equipment and processes while achieving similar planarization results through simpler deposition and etching steps.
2Manufacturing precision
If CMP process is used for planarization, then planarization can be achieved, but material compatibility is limited
Solution Approach 1:
The patent changes the fundamental parameters of the planarization approach by using deposition thickness control and etching selectivity instead of mechanical polishing parameters. The passivation layer is deposited to a controlled thickness and then isotropically etched, allowing the process to work with various materials including aluminum nitride and silicon nitride that are incompatible with traditional CMP processes. This parameter change enables universal application across different material systems.
3Manufacturing precision
If whole product is planarized by CMP, then uniform planarization is achieved, but localized control is lost
Solution Approach 1:
The patent applies local quality by making the passivation layer thickness and etching characteristics location-dependent. The passivation layer is deposited conformally but with varying local thickness, and the isotropic etching process removes material at different rates in different locations. This allows simultaneous achievement of uniform planarization in critical areas while maintaining localized control for specific functional regions, resolving the contradiction between uniformity and localized control.
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
The method simplifies the planarization process, enhances control and uniformity, and expands material compatibility, achieving effective partial planarization with reduced complexity and cost compared to traditional CMP methods.
Implementation Method 1
depositing a passivation layer on the second electrode layer for covering the second electrode layer and the piezoelectric layer
Implementation Method 2
totally etching the passivation layer until a thickness of the passivation layer is reduced to a predetermined thickness
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.