Nitride Semiconductor Gate Structure for Low-Leakage Isolation
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Solution Overview
Problem
The existing manufacturing process for nitride semiconductor devices damages the surface of the barrier layer during the removal of masks, leading to increased leakage current between the source/drain electrode and the gate electrode.
Innovation Solution
The nitride semiconductor device is manufactured using a method that forms an inactive region with a concave structure around the active region, using the gate electrode as a mask instead of a photoresist, and retaining the first insulating film as part of the final product to reduce surface damage and leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a photoresist mask is used for device isolation etching, then the transistor region can be protected during etching, but the mask must be removed by ashing which damages the barrier layer surface and increases leakage current
Solution Approach 1:
The invention extracts and removes the harmful photoresist mask from the process entirely. Instead of using a photoresist mask that requires ashing removal (which damages the barrier layer), the patent uses the gate electrode itself as a permanent mask for device isolation etching. This eliminates the need for mask removal and prevents surface damage to the barrier layer, thereby reducing leakage current while maintaining manufacturing precision.
Solution Approach 2:
The gate electrode serves multiple functions: it acts as the control electrode for the transistor operation and simultaneously serves as the mask for device isolation etching. This multi-functionality eliminates the need for a separate photoresist mask and its subsequent removal, preventing barrier layer damage and reducing leakage current.
2Reliability
If the gate electrode is used as a mask for device isolation etching, then the barrier layer surface is protected from damage and leakage current is reduced, but an additional etching step is required after gate electrode formation
Solution Approach 1:
The invention merges the gate electrode formation step with the device isolation etching step. The gate electrode is formed first, then immediately used as the mask for device isolation etching. This combination eliminates the need for separate photoresist mask application and removal steps, reducing overall process complexity despite adding an etching step, while significantly improving reliability by preventing barrier layer damage.
3Ease of manufacture
If photoresist mask is removed by ashing, then the mask can be completely removed, but the barrier layer surface is damaged creating leakage paths
Solution Approach 1:
The invention extracts and eliminates the photoresist mask from the process entirely. By using the gate electrode as a permanent mask, there is no need for mask removal by ashing, thus preventing barrier layer surface damage and the resulting leakage current while maintaining ease of manufacture.
Solution Approach 2:
The invention replaces the disposable photoresist mask (which must be removed and causes damage) with a permanent structural element (the gate electrode) that serves dual purposes. This eliminates the need for mask removal and prevents the harmful effects of ashing on the barrier layer.
Data Source
AI summary
A nitride semiconductor device includes a channel layer, a barrier layer made of AlxInyGa1-x-yN (x>0, x+y≤1), an active region that has a layered structure including the channel layer and the barrier layer, an inactive region that is formed at the layered structure around the active region and that is a concave portion having a bottom portion that reaches the channel layer, a gate layer made of a nitride semiconductor selectively formed on the barrier layer in the active region, a gate electrode formed on the gate layer, a first insulating film that covers the gate electrode and that is in contact with the barrier layer in the active region, and a second insulating film that covers the first insulating film and that is in contact with the inactive region.