Semiconductor Insulation Film Lamination Structure
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Solution Overview
Problem
Current semiconductor devices using nitride semiconductors face challenges in improving characteristics such as breakdown voltage, etching resistance, and current collapse, particularly in the insulation film composition and structure.
Innovation Solution
A semiconductor device with a lamination structure of Si-rich and N-rich silicon nitride films in the insulation film, where the Si-rich film is on top and the N-rich film is underneath, enhancing breakdown voltage and etching resistance while suppressing current collapse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single-layer silicon nitride film is used as the insulation film, then the manufacturing process is simple, but the breakdown voltage and etching resistance are insufficient
Solution Approach 1:
The insulation film is divided into multiple layers: a first silicon nitride film layer and a second silicon nitride film layer with different composition ratios. This segmentation allows each layer to contribute different properties, improving overall breakdown voltage and etching resistance while maintaining manufacturing feasibility through sequential deposition processes.
Solution Approach 2:
The patent employs a composite insulation film structure combining silicon nitride films with different Si/N composition ratios. The first film has a composition ratio of Si to N of 0.65 or more and 0.85 or less, while the second film has a composition ratio of Si to N of more than 0.85. This composite structure synergistically improves breakdown voltage and etching resistance beyond what a single-layer film can achieve.
2Object-affected harmful factors
If the silicon nitride film has high silicon content for etching resistance, then etching resistance improves, but current collapse increases
Solution Approach 1:
The insulation film is segmented into two layers with different Si/N composition ratios. The first silicon nitride film layer has a balanced composition (Si/N ratio of 0.65-0.85) that provides moderate etching resistance while maintaining good surface passivation to reduce current collapse. The second silicon nitride film layer has high silicon content (Si/N ratio >0.85) that provides enhanced etching resistance. This segmentation allows each layer to optimize for its specific function without compromising the other.
Solution Approach 2:
Different regions of the insulation film structure are assigned different composition qualities. The first film layer (closer to the semiconductor surface) has a composition optimized for surface passivation and current collapse suppression, while the second film layer (outer layer) has a composition optimized for etching resistance. This local quality differentiation resolves the contradiction by allowing each region to excel at its primary function.
3Object-generated harmful factors
If a nitrogen-rich silicon nitride film is used to suppress current collapse, then current collapse reduces, but etching resistance decreases
Solution Approach 1:
The insulation film is divided into two functional layers: the first silicon nitride film layer with lower Si/N ratio (0.65-0.85) that provides good surface passivation and current collapse suppression, and the second silicon nitride film layer with higher Si/N ratio (>0.85) that provides strong etching resistance. This segmentation allows the nitrogen-richer first layer to suppress current collapse while the silicon-richer second layer compensates for etching resistance.
Solution Approach 2:
The patent merges two silicon nitride films with different properties into a single composite insulation structure. The first film (more nitrogen-rich) and second film (more silicon-rich) are deposited sequentially to form an integrated structure that combines the advantages of both compositions: current collapse suppression from the nitrogen-rich layer and etching resistance from the silicon-rich layer.
Data Source
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AI summary
The characteristics of a semiconductor device are improved. A semiconductor device is formed so as to have a channel layer formed over a substrate, a barrier layer, a trench penetrating through the barrier layer in an opening region, and reaching some point of the channel layer, a gate electrode arranged in the trench via a gate insulation film, and an insulation film formed over the barrier layer outside the opening region. Then, the insulation film has a lamination structure of a Si-rich silicon nitride film, and a N-rich silicon nitride film situated thereunder. Thus, the upper layer of the insulation film is set as the Si-rich silicon nitride film. This enables the improvement of the breakdown voltage, and further, enables the improvement of the etching resistance. Whereas, the lower layer of the insulation film is set as the N-rich silicon nitride film. This can suppress collapse.