Inductor Magnetic Layer Etching with Oxide Mask
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Solution Overview
Problem
The existing methods for forming inductors face challenges in achieving a large enough volume of the magnetic layer, which results in decreased performance, particularly a lower Q factor due to the uneven etching rates leading to excessive lateral etching, thereby reducing the magnetic layer's volume.
Innovation Solution
The formation of an oxide layer below a portion of the magnetic layer to prevent over-etching, allowing for a larger volume of the magnetic layer by using an oxide layer as a protection and base, resulting in a polygon or trapezoid structure with increased inductance and improved Q factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching methods are used to form the magnetic layer, then the etching process can be completed, but the lateral etching rate is higher than the vertical etching rate causing excessive lateral etching and reduced magnetic layer volume
Solution Approach 1:
An oxide layer is introduced as an intermediary protective layer between the etching process and the magnetic layer. This oxide layer acts as a mask during etching, preventing excessive lateral etching of the magnetic layer while allowing controlled vertical etching, thereby preserving the magnetic layer volume and improving etching precision simultaneously.
Solution Approach 2:
The oxide layer is formed in advance before the etching process. This preliminary formation of the protective oxide layer ensures that when etching occurs, the magnetic layer is already protected, preventing the harmful lateral etching effect before it can occur.
2Reliability
If the magnetic layer volume is increased to improve inductance and Q factor, then the inductor performance is improved, but the etching process removes excessive material reducing the volume
Solution Approach 1:
The oxide layer serves as a protective intermediary that prevents excessive material loss during etching. By placing the oxide layer over the magnetic layer before etching, the magnetic material is protected from unwanted removal, preserving the magnetic layer volume needed for high inductance and Q factor while still allowing the etching process to define the structure.
3Productivity
If the etching rate is increased to improve manufacturing efficiency, then the etching process is faster, but the uneven etching rates lead to excessive lateral etching and performance degradation
Solution Approach 1:
The oxide layer acts as a protective intermediary that enables faster etching speeds without sacrificing precision. By having the oxide layer in place, the etching process can proceed more aggressively while the oxide protects the magnetic layer from excessive lateral removal, maintaining etching uniformity even at higher speeds.
Data Source
AI summary
A method for forming an inductor structure is provided. The method includes forming a first metal layer over a substrate and forming an oxide layer over the first metal layer. The method also includes forming a magnetic material in and over the oxide layer, and the magnetic material includes a first portion and a second portion, the first portion is directly over the oxide layer, and the second portion is in the oxide layer. The method further includes removing the first portion and a portion of the second portion of the magnetic material to form a magnetic layer, such that a recession is between the magnetic layer and the oxide layer. The method further includes forming a dielectric layer over the magnetic layer, wherein the recession is filled with the dielectric layer.