Hollow Structure Around Semiconductor Electrode
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Solution Overview
Problem
The use of resin films in semiconductor devices leads to increased parasitic capacitance and deteriorated high-frequency gain due to residual sacrificial layers under gate electrodes, particularly in Y-type or T-type gate structures, as the etching process is inefficient in removing the sacrificial layer from minute spaces.
Innovation Solution
A method is developed to form a hollow structure around semiconductor elements by using two resin films that enclose the electrode without a sacrificial layer, ensuring no etching residue remains and preventing parasitic capacitance increase, where the first resin film forms the side wall and the second resin film forms the top plate of the hollow structure, with a high moisture-resistant insulating film covering the element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a sacrificial layer is used to form a hollow structure around a semiconductor element, then the hollow structure can be formed, but etching residues remain in minute spaces under gate electrodes causing parasitic capacitance increase
Solution Approach 1:
The patent extracts and removes the problematic sacrificial layer completely using a lift-off process, replacing it with a protective film that does not leave residues. This eliminates the source of etching residues while maintaining the hollow structure formation capability.
Solution Approach 2:
The patent introduces a protective film as an intermediary material that replaces the sacrificial layer. This protective film serves as a mediator that can be cleanly removed without leaving residues, thereby preventing parasitic capacitance increase while still enabling hollow structure formation.
2Shape
If resin films are used to enclose the electrode, then the hollow structure is formed, but parasitic capacitance increases due to resin proximity to the electrode
Solution Approach 1:
The patent applies different material properties to different regions: the protective film is positioned close to the electrode where low dielectric constant is critical to minimize parasitic capacitance, while resin films are used in regions where mechanical protection is needed but can be positioned farther from the electrode.
Solution Approach 2:
The patent changes the dielectric parameter by using a protective film with lower dielectric constant near the electrode, thereby reducing parasitic capacitance while maintaining the hollow structure configuration.
3Shape
If etching is used to remove the sacrificial layer, then the hollow structure is formed, but the etching gas cannot enter micro crevices effectively causing incomplete removal
Solution Approach 1:
The patent replaces the mechanical/chemical etching process with a lift-off process that uses solvent dissolution. This substitution allows complete removal of the sacrificial layer without the limitations of gas penetration into micro crevices, thereby eliminating etching residues.
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 the increase in parasitic capacitance and maintains the high-frequency gain of semiconductor devices by eliminating etching residues and ensuring efficient etching, as demonstrated by improved conversion gain in transmission amplifiers.
Implementation Method 1
bonding a second resin film that covers over the electrode while keeping a distance from the electrode of the semiconductor element to a top surface of the first resin film
Data Source
AI summary
A method for manufacturing a semiconductor device includes: forming a semiconductor element having an electrode on a main surface of a semiconductor substrate; forming a first resin film that encloses a side of the electrode while keeping a distance from the electrode of the semiconductor element on the main surface of the semiconductor substrate; and forming a hollow structure around the electrode of the semiconductor element by bonding a second resin film that covers over the electrode while keeping a distance from the electrode of the semiconductor element to a top surface of the first resin film.