MEMS Singulation Using Plasma Etching to Protect Bond Pad Shelves
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Solution Overview
Problem
Existing MEMS device manufacturing techniques risk damaging bond pad shelves during wafer singulation, leading to suboptimal manufacturing yield.
Innovation Solution
A method involving sawing through a first portion of a semiconductor interposer, plasma etching through a second portion, and forming openings in oxide layers to expose bond pads, while using plasma or liquid jet techniques to mitigate damage to bond pads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If sawing is used to cut through the entire semiconductor interposer, then wafer singulation is completed, but bond pad shelves are at risk of physical damage
Solution Approach 1:
The cutting process is divided into two distinct segments: a first saw cut that removes a first portion of the interposer, and a second plasma etch that removes a second portion. This segmentation allows each method to be optimized for its specific function, with sawing providing rapid material removal and plasma etching providing precise, damage-free completion of the cut.
Solution Approach 2:
The patent replaces the mechanical sawing system with a plasma etching system for removing the second portion of the interposer. Plasma etching uses ionized gas to chemically erode material rather than mechanical force, eliminating the risk of mechanical damage to the bond pad shelves while still achieving complete interposer removal.
2Reliability
If plasma etching is used to remove interposer material, then bond pad shelves are protected from mechanical damage, but manufacturing process complexity increases
Solution Approach 1:
The manufacturing process is segmented into distinct phases with clearly defined objectives. The first saw cut phase removes the bulk of the interposer material efficiently, while the second plasma etch phase precisely removes the remaining material. This segmentation makes the complex process more manageable and allows each step to be optimized independently.
Solution Approach 2:
The first saw cut performs a preliminary action by removing the majority of the interposer material before the plasma etching begins. This preliminary removal reduces the workload for the plasma etch step, allowing it to focus on the critical task of removing only the final portion near the bond pads without having to process the entire interposer thickness.
3Reliability
If multiple cutting methods are used, then manufacturing yield is enhanced, but processing time increases
Solution Approach 1:
The sawing process performs a partial action by removing only the first portion of the interposer, leaving a controlled remainder. This partial removal is intentional and optimized, where the saw cuts through most of the interposer quickly but stops before reaching the critical bond pad region, balancing speed with safety.
Solution Approach 2:
The patent substitutes plasma etching for mechanical sawing in the critical final removal step. While plasma etching is slower than sawing, it is only applied to the second, smaller portion of the interposer, minimizing the time penalty while maximizing the protection of bond pads from mechanical damage.
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
Significantly reduces the risk of physical damage to bond pad shelves, enhancing manufacturing yield and ensuring the integrity of MEMS devices.
Implementation Method 1
plasma etching through a second portion of the semiconductor interposer using the first opening to form a second opening
Data Source
AI summary
In examples, an electronic device includes a semiconductor die including circuitry, a microelectromechanical systems (MEMS) element on the semiconductor die and coupled to the circuitry, a bond pad on the semiconductor die and coupled to the circuitry, and a bondline on the semiconductor die between the MEMS element and the bond pad, with the bondline circumscribing the MEMS element. The electronic device includes a semiconductor interposer coupled to the bondline and having a striated exterior surface facing away from the MEMS element.