Beveled Cutting Tool for Exposing Metallization Pads
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Solution Overview
Problem
Bulk acoustic wave resonators incorporating polycrystalline piezoelectric thin films face challenges at frequencies above 5 GHz due to reduced crystallinity, which affects their performance in wireless data communications.
Innovation Solution
A method involving a cutting tool with a beveled side surface and flat tip surface is used to expose metallization pads on a semiconductor wafer, forming a tapered channel to improve contact with conductive material, enabling effective ohmic contact and enhancing the performance of single crystal bulk acoustic wave resonator devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional cutting tool with a flat tip is used to expose metallization pads, then the cutting process is simple, but the contact area between conductive material and metallization pad is insufficient, leading to poor ohmic contact
Solution Approach 1:
The cutting tool tip is designed with an asymmetric beveled configuration instead of a symmetric flat tip. The beveled surface creates a tapered channel that naturally guides conductive material flow, improving contact area with the metallization pad while adding minimal structural complexity to the cutting tool
Solution Approach 2:
The cutting tool transitions from a two-dimensional flat tip to a three-dimensional beveled structure. This dimensional change creates a tapered channel that provides both mechanical cutting function and a pathway for conductive material deposition, simultaneously achieving pad exposure and improved ohmic contact
2Ease of manufacture
If polycrystalline piezoelectric thin films are used in bulk acoustic wave resonators, then manufacturing is easier, but performance degrades at frequencies above 5 GHz due to reduced crystallinity
Solution Approach 1:
The patent changes the material parameter from polycrystalline to single crystal structure. This fundamental material parameter change enables the resonator to maintain high crystallinity and superior performance at frequencies above 5 GHz, while the wafer-level processing methodology preserves manufacturing efficiency
3Reliability
If the cap structure is removed completely to expose metallization pads, then contact area is maximized, but device protection and structural integrity are compromised
Solution Approach 1:
Instead of removing the entire cap structure, the patent selectively extracts only the necessary portion covering the metallization pad. This creates a localized channel that provides adequate electrical contact area while preserving the majority of the cap structure for continued device protection and mechanical support
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 contact between conductive material and metallization pads, addressing the limitations of polycrystalline thin films at higher frequencies and enhancing the performance of bulk acoustic wave resonators for applications in communication and computing devices.
Implementation Method 1
A channel can be cut in a portion of the cap structure that covers the metallization pad using a cutting tool having a tip surface and a beveled side surface
Implementation Method 2
conductive material can be deposited in the channel to ohmically contact the upper surface of the metallization pad in the channel
Data Source
AI summary
A method of fabricating a semiconductor device can include providing an integrated circuit electrically coupled to a metallization pad on a semiconductor wafer, the integrated circuit and the metallization pad covered by a cap structure. A channel can be cut in a portion of the cap structure that covers the metallization pad using a cutting tool having a tip surface and a beveled side surface to expose an upper surface of the metallization pad in the channel extending in a first direction and a conductive material can be deposited in the channel to ohmically contact the upper surface of the metallization pad in the channel.