HEMT Contact Structure With Controlled Etching and Leakage Reduction
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Solution Overview
Problem
The manufacturing of high electron mobility transistors faces issues during the etching process, where insufficient etching can result in non-penetrating contact openings or residue on semiconductor surfaces, while over-etching causes damage, leading to defective contacts and yield loss.
Innovation Solution
A semiconductor structure with a substrate, channel, barrier, and passivation layers, where an etching process using fluorine-based gases without chlorine controls the etching depth and forms an extending portion of the insulating layer to ensure proper contact formation, reducing leakage current and enhancing contact quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching processes are used to form contact openings, then contact openings can be formed, but insufficient etching causes non-penetrating openings or residues while over-etching causes damage to semiconductor layers
Solution Approach 1:
The patent changes the chemical composition parameter of the etching gas from conventional chlorine-based gases to fluorine-based gases. This parameter change fundamentally alters the etching chemistry to achieve selective removal of the insulating layer without damaging the underlying semiconductor layers, thereby simultaneously achieving precise depth control and contact reliability.
Solution Approach 2:
The patent introduces an intermediary insulating layer configuration where the insulating layer extends beyond the contact opening region to form a protective overhang. This intermediary structure acts as a physical barrier that prevents direct contact between the etching plasma and the semiconductor layer edges, protecting against over-etching damage while allowing complete penetration of the contact opening.
2Manufacturing precision
If etching is extended to ensure complete penetration, then contact openings can be formed, but excessive loss and damages occur to the semiconductor layer
Solution Approach 1:
The patent changes the chemical selectivity parameter by using fluorine-based etching gases that have high selectivity for the insulating layer over the semiconductor layer. This allows the etching process to continue until complete penetration is achieved without causing excessive loss or damage to the semiconductor layer, as the fluorine-based chemistry preferentially reacts with the insulating layer material.
Solution Approach 2:
The extended insulating layer acts as an intermediary protective structure that sacrificially absorbs the etching process. By designing the insulating layer to extend beyond the contact opening, it provides a buffer zone that allows aggressive etching to achieve complete penetration while the overhanging insulating material protects the semiconductor layer edges from excessive removal.
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 ensures better contact quality and electrical properties by preventing under-etching and over-etching issues, reducing leakage current, and improving the performance of high electron mobility transistors for high-frequency applications.
Implementation Method 1
an etching process using fluorine-based gases without chlorine controls the etching depth
Data Source
AI summary
A semiconductor structure includes a substrate, a channel layer on the substrate, a barrier layer on the channel layer, a first passivation layer on the insulating layer, a contact structure disposed on the first passivation layer and extending through the first passivation layer to directly contact a portion of the barrier layer, and an insulating layer interposed between the barrier layer and the first passivation layer and comprising an extending portion protruding toward a bottom corner of the contact structure.