Nitrogen Gate Oxide Layout for Source-Region TDDB Reliability
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Solution Overview
Problem
The existing vertical power device structure has a gate insulating film with a shorter Time-Dependent Dielectric Breakdown (TDDB) lifetime on the source region compared to the epitaxial layer and body region, limiting the long-term reliability of the device.
Innovation Solution
A semiconductor device with a gate insulating film containing nitrogen atoms, where the third portion in contact with the source region has a thickness greater than the first and second portions, reducing the electric field and leak current, thereby enhancing the TDDB lifetime and reliability of the gate insulating film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a silicon oxide film is formed as an interlayer insulating film using a chemical vapor deposition (CVD) method, then the film can be formed at a relatively low temperature, but the film density becomes low and pinholes are generated
Solution Approach 1:
The film formation process is divided into two separate stages: first forming a base silicon oxide film at low temperature, then forming an additional silicon oxide film at high temperature. This segmentation allows each stage to optimize for its specific purpose - the first stage ensures low temperature compatibility while the second stage ensures high density and quality
Solution Approach 2:
A base silicon oxide film is formed in advance at low temperature before the final high-temperature film formation. This preliminary action creates a foundation that can be subsequently improved by the high-temperature process without requiring the entire structure to withstand high temperatures
2Temperature
If a silicon nitride film is formed as an interlayer insulating film using a CVD method, then the film can be formed at a relatively low temperature, but the film density becomes low and pinholes are generated
Solution Approach 1:
The film formation process is divided into two separate stages: first forming a base silicon nitride film at low temperature, then forming an additional silicon nitride film at high temperature. This segmentation allows each stage to optimize for its specific purpose - the first stage ensures low temperature compatibility while the second stage ensures high density and quality
Solution Approach 2:
A base silicon nitride film is formed in advance at low temperature before the final high-temperature film formation. This preliminary action creates a foundation that can be subsequently improved by the high-temperature process without requiring the entire structure to withstand high temperatures
3Temperature
If an organic material is used as a resist pattern, then the resist pattern can be formed at a low temperature, but outgassing occurs during heat treatment causing pinholes in the silicon oxide film
Solution Approach 1:
The silicon oxide film is formed in advance before the organic resist pattern is applied and processed. This preliminary action ensures the film structure is established before any potential outgassing events, so that even if pinholes form during resist processing, the critical insulating structure is already in place
Solution Approach 2:
Instead of forming the silicon oxide film after the resist pattern (which would protect the film from outgassing), the patent inverts the sequence by forming the film first. This allows the organic resist to be processed without compromising the integrity of the underlying silicon oxide film
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 semiconductor device achieves a significantly improved TDDB lifetime and reliability of the gate insulating film, ensuring long-term device reliability and performance.
Implementation Method 1
heat treatment apparatus for heating a semiconductor wafer
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3B
AI summary
A semiconductor device includes a first conductive-type semiconductor layer, a second conductive-type body region formed in a surficial portion of the semiconductor layer, a first conductive-type source region formed in a surficial portion of the body region, a gate insulating film provided on the semiconductor layer and containing nitrogen atoms, the gate insulating film including a first portion in contact with the semiconductor layer outside the body region, a secondportion in contact with the body region, and a third portion in contact with the source region, and a gate electrode provided on the gate insulating film in an area extending across the semiconductor layer outside the body region, the body region, and the source region. The third portion of the gate insulating film has a thickness greater than the thickness of the first portion and the thickness of the second portion.