Nitride Semiconductor Gate Masking to Reduce Etch Leakage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing nitride semiconductor devices face surface damage during the etching process, leading to increased leakage current due to the use of photoresist masks, which are unnecessary in the final product and require ashing, causing further damage.
Innovation Solution
A nitride semiconductor device with a layered structure incorporating a barrier layer and an inactive region formed using a gate electrode as a mask, eliminating the need for photoresist and reducing surface damage, thereby minimizing leakage current through the interface with insulating films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a photoresist mask is used during etching to protect the transistor region, then etching precision is improved, but the barrier layer surface is damaged by subsequent ashing, increasing leakage current
Solution Approach 1:
The patent removes the photoresist mask from the process entirely. Instead of using a photoresist mask followed by ashing, the invention uses the gate electrode itself as a mask during etching, eliminating the need for photoresist and subsequent ashing steps that cause surface damage to the barrier layer.
Solution Approach 2:
The gate electrode serves a dual function: as the functional element of the transistor and as the etching mask. This self-service approach eliminates the need for separate photoresist masking and subsequent removal steps, thereby preventing surface damage to the barrier layer while maintaining etching precision.
2Ease of manufacture
If photoresist mask is removed by ashing, then the mask is eliminated from the final product, but the barrier layer surface is damaged, creating leakage paths
Solution Approach 1:
The patent extracts the harmful ashing step from the manufacturing process by using the gate electrode as a permanent mask. This eliminates the need for photoresist removal while preventing surface damage to the barrier layer, thereby maintaining reliability and reducing leakage current.
Solution Approach 2:
Instead of using disposable photoresist masks that require removal, the invention employs the gate electrode as a reusable mask that remains in the final product. This eliminates the need for mask removal operations and prevents the surface damage associated with ashing.
3Productivity
If the barrier layer surface is damaged, then leakage current increases between source/drain and gate electrodes, but device functionality is compromised
Solution Approach 1:
The patent applies preliminary anti-action by using the gate electrode as a mask during etching to prevent surface damage to the barrier layer before leakage paths can form. This proactive approach maintains the integrity of the barrier layer and prevents leakage current while preserving device functionality.
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
The solution effectively reduces surface damage and leakage current by using the gate electrode as a mask during the formation of the inactive region, ensuring a continuous process flow that maintains the integrity of the barrier layer and reduces interface state densities.
Implementation Method 1
using a gate electrode as a mask, inactive region formation is performed
Implementation Method 2
a barrier layer that is formed on the channel layer... reducing leakage current through the interface with insulating films
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.