BAW Resonator Lower Electrode Etching for Dielectric Coverage
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Solution Overview
Problem
The existing manufacturing process for bulk acoustic wave (BAW) resonator packages often results in a reverse slope on the lower electrode, leading to short circuits and coverage failures due to the use of a single dry etching process with a hardmask, which fails to etch the upper end portion of the electrode, causing a discontinuous dielectric layer and subsequent short circuits between the upper and lower electrodes.
Innovation Solution
A method involving multiple etching operations with hardmasks patterned in different shapes, using specific etching gases that only etch the hardmask or the lower electrode, to create a lower electrode with varying thicknesses and shapes, preventing reverse slopes and ensuring continuous dielectric coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single dry etching process with hardmask is used to pattern the lower electrode, then the manufacturing process is simple and fast, but a reverse slope is generated on the lower electrode causing coverage failure and short circuits
Solution Approach 1:
The single etching process is segmented into multiple etching steps with different hardmask patterns. The first etching step creates an initial pattern, and the second etching step refines the pattern to eliminate reverse slope. This segmentation allows each step to optimize for different requirements, preventing coverage failure while maintaining manufacturing efficiency.
Solution Approach 2:
The first etching step performs preliminary patterning of the lower electrode, creating a rough pattern that is then refined in the second step. This preliminary action prepares the electrode for the final precise patterning, ensuring that the reverse slope issue is addressed in the refinement step while maintaining overall process efficiency.
2Manufacturing precision
If the lower electrode is fully etched using the hardmask, then the electrode pattern is complete, but the upper end portion adjacent to the hardmask is not etched due to gas inability to etch the hardmask, generating a reverse slope
Solution Approach 1:
Instead of trying to etch the electrode uniformly in a single step, the process inverts the approach by using two steps with different hardmask patterns. The first step creates a pattern that intentionally leaves certain areas, and the second step completes the patterning by etching those previously protected areas, thereby eliminating the reverse slope problem.
Solution Approach 2:
Different regions of the lower electrode receive different etching treatments through the two-step process. The first etching step patterns most of the electrode, while the second step specifically addresses the upper end portion adjacent to the hardmask. This local quality approach ensures that each region is etched to the appropriate depth and geometry, preventing reverse slope formation.
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 effectively prevents short circuits and coverage failures, enhancing the quality of the resonator package by ensuring proper insulation and continuous dielectric coverage, as demonstrated by a significant reduction in short circuit occurrence from 50% to 1% at higher voltages.
Implementation Method 1
etching a lower electrode with a hardmask, in which only a portion of a thickness of the lower electrode is etched to shape the lower electrode
Data Source
AI summary
A resonator package and a method of manufacturing the same are provided. The method of manufacturing a resonator package involves etching a lower electrode with a hardmask, in which only a portion of a thickness of the lower electrode is etched to shape the lower electrode.