SiC MOS-Gate Device Interlayer Insulation Moisture Control
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Solution Overview
Problem
Conventional silicon carbide semiconductor devices face issues with moisture absorption by interlayer insulating films leading to outward diffusion of boron and phosphorus atoms, causing device failures and gate threshold voltage variations due to low boron and phosphorus concentrations, and fluorine addition not effectively preventing this diffusion.
Innovation Solution
A silicon carbide semiconductor device with a 2-layer interlayer insulating film structure comprising a non-doped silicon oxide film and a boron-phosphorus oxide film, where the boron concentration is between 4.5 mol% to 8.0 mol% and phosphorus concentration is between 1.0 mol% to 3.5 mol%, suppressing outward diffusion and maintaining moisture content to stabilize the gate threshold voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If fluorine is added to the interlayer insulating film to improve reflow properties, then the reflow temperature is reduced, but boron and phosphorus atoms still diffuse outward causing device failures
Solution Approach 1:
The patent changes the chemical composition parameters of the interlayer insulating film by adding aluminum at a concentration of 0.1 times to 1 time the total sum of boron and phosphorus concentrations. This parameter change modifies the film's reflow properties and moisture absorption characteristics, enabling effective prevention of boron and phosphorus diffusion while maintaining manufacturing feasibility.
Solution Approach 2:
The patent creates a composite interlayer insulating film by combining boron, phosphorus, and aluminum dopants within the glass matrix. This composite material approach leverages the synergistic effects of multiple dopants: boron and phosphorus provide reflow properties, while aluminum specifically prevents outward diffusion of boron and phosphorus atoms, solving the reliability issue.
2Ease of manufacture
If the interlayer insulating film absorbs moisture, then reflow properties are improved, but boron and phosphorus atoms diffuse outward causing device failures
Solution Approach 1:
The patent modifies the chemical composition parameters by adding aluminum dopant at a specific concentration range (0.1 to 1 time the total sum of boron and phosphorus concentrations). This parameter change alters the film's interaction with moisture, enabling the film to maintain necessary moisture content for reflow while preventing boron and phosphorus diffusion through the aluminum barrier effect.
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 enhanced hygroscopicity of the interlayer film maintains moisture levels, preventing boron and phosphorus atom diffusion, thus stabilizing gate threshold voltage and reducing device failures by suppressing outward diffusion and maintaining moisture content.
Implementation Method 1
The enhanced hygroscopicity of the interlayer film maintains moisture levels, preventing boron and phosphorus atom diffusion
Implementation Method 2
A silicon carbide semiconductor device with a 2-layer interlayer insulating film structure comprising a non-doped silicon oxide film and a boron-phosphorus oxide film, where the boron concentration is between 4.5 mol% to 8.0 mol% and phosphorus concentration is between 1.0 mol% to 3.5 mol%, suppressing outward diffusion and maintaining moisture content to stabilize the gate threshold voltage
Data Source
AI summary
A MOS-gate silicon carbide semiconductor device has an interlayer insulating film that covers a gate electrode and that has a 2-layer structure in which a NSG film and a BPSG film are sequentially stacked. The BPSG film has a boron concentration in a range from 4.5 mol % to 8.0 mol %. The BPSG film has a phosphorus concentration in a range from 1.0 mol % to 3.5 mol %. The NSG film has a thickness in a range from 50 nm to 400 nm. The BPSG film has a thickness in a range from 400 nm to 800 nm. A distance from the gate insulating film to the BPSG film is at most 100 nm at a portion where the gate insulating film and the BPSG film oppose each other across the NSG film.