Silicon Nitride Layer Refractive Index for Semiconductor Reliability
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Solution Overview
Problem
There is a demand to reduce the resistance of conductive layers and limit leak currents in semiconductor devices, particularly between compound semiconductor layers and insulating layers, which existing technologies have not adequately addressed.
Innovation Solution
A silicon nitride layer with a refractive index of less than 1.85 is formed on a compound semiconductor layer using plasma CVD, and a denser protective silicon nitride layer is added on top, reducing contact resistance and leak currents while improving humidity resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional silicon nitride layer with refraction index >= 1.85 is formed on the compound semiconductor layer, then the insulating property is sufficient, but the contact resistance of the conductive layer increases and leak current occurs at the interface
Solution Approach 1:
The patent changes the refraction index parameter of the silicon nitride layer from conventional values (>=1.85) to a specific lower range (1.68-1.85), which fundamentally alters the layer's electrical properties. This parameter change reduces contact resistance and prevents leak current while maintaining adequate insulation, resolving the contradiction between insulating property and electrical conductivity.
Solution Approach 2:
The patent employs a composite structure with two different silicon nitride layers: a first silicon nitride layer with refraction index 1.68-1.85 for low contact resistance and minimal leak current, and a second silicon nitride layer with refraction index >=1.96 for high insulation. This composite material approach allows simultaneous optimization of both electrical conductivity and insulating property.
2Reliability
If the silicon nitride layer has higher refraction index for better insulation, then the insulating performance improves, but the humidity resistance of the semiconductor device deteriorates
Solution Approach 1:
The patent identifies that higher refraction index silicon nitride layers exhibit poorer humidity resistance. By changing the refraction index parameter to the optimal range of 1.68-1.85 for the first layer, the patent achieves both adequate insulation and superior humidity resistance, preventing moisture penetration that would degrade device performance.
Solution Approach 2:
The patent uses a composite structure where the first silicon nitride layer with refraction index 1.68-1.85 provides humidity barrier functionality, while the second silicon nitride layer with refraction index >=1.96 provides enhanced insulation. This division of functional responsibilities within the composite structure resolves the contradiction between insulating performance and humidity resistance.
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 the resistance of conductive layers and limits leak currents between the compound semiconductor and insulating layers, enhancing the performance and reliability of semiconductor devices, especially under high-temperature and high-power conditions.
Implementation Method 1
forming a silicon nitride layer on a compound semiconductor layer with a plasma CVD method
Data Source
AI summary
A fabrication method of a semiconductor device includes forming a silicon nitride layer on a compound semiconductor layer with a plasma CVD method and selectively treating the compound semiconductor layer with use of the silicon nitride layer for a mask. The silicon nitride layer has a refraction index of less than 1.85. The compound semiconductor layer includes Ga.