Trench Gate Switching Device Insulation for Higher Withstand Voltage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for manufacturing switching devices face challenges in ensuring the withstand voltage of interlayer insulation films, leading to thicker film thickness and reduced contact area between electrodes, which affects the reliability and performance of the devices.
Innovation Solution
The method involves forming a trench on a semiconductor substrate, depositing a gate insulation film and gate electrode, oxidizing the gate electrode to create an oxide film, and using vapor phase growth to form an interlayer insulation film with a top surface below the substrate surface, allowing for a double-layered insulation structure that reduces film thickness while maintaining withstand voltage, and forming a nickel silicide layer to enhance contact area and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the interlayer insulation film is made thicker to ensure withstand voltage, then the reliability is improved, but the contact area between electrodes is reduced
Solution Approach 1:
The interlayer insulation film is divided into two separate layers: a first interlayer insulation film formed by CVD and a second interlayer insulation film formed by etching. This segmentation allows each layer to have optimized thickness and properties, enabling the first layer to provide sufficient withstand voltage while the second layer maintains adequate contact area, thus resolving the contradiction between reliability and contact area.
2Reliability
If the interlayer insulation film is made thicker to ensure withstand voltage, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The insulation structure is segmented into two distinct films with different formation methods and properties. The first film (CVD) provides the primary insulation and withstand voltage, while the second film (etched) fine-tunes the insulation thickness. This segmentation achieves reliable withstand voltage without requiring a single excessively thick film, thereby controlling device complexity.
Solution Approach 2:
The first interlayer insulation film is formed in advance by CVD deposition before the final etching step creates the second film. This preliminary action establishes a robust base insulation layer that ensures withstand voltage requirements are met, allowing subsequent processing to focus on optimizing contact area without compromising reliability.
3Length of stationary object
If vapor phase growth is used to form the interlayer insulation film, then the film thickness is reduced, but the withstand voltage may be compromised
Solution Approach 1:
The vapor phase growth process is applied selectively to form only the second interlayer insulation film, while the first film is formed by CVD. This segmentation allows the thinner second film (formed by vapor phase growth) to be compensated by the presence of the first film, ensuring total insulation thickness and withstand voltage are sufficient while still achieving overall thickness reduction compared to conventional single-layer approaches.
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
This approach reduces the overall insulation film thickness, increases the contact area between electrodes, and stabilizes the gate threshold value, resulting in improved reliability and performance of the switching device by ensuring higher withstand voltage and lower impurity content in the oxide film.
Implementation Method 1
forming an oxide film by oxidizing the top surface of the gate electrode
Implementation Method 2
forming an interlayer insulation film by vapor phase growth at a top surface of the oxide film
Data Source
AI summary
A method for manufacturing a switching device includes: forming a trench at a top surface of a semiconductor substrate; forming a gate insulation film for covering an inner surface of the trench; forming a gate electrode inside the trench to locate a top surface of the gate electrode below the top surface of the semiconductor substrate; forming an oxide film by oxidizing the top surface of the gate electrode; forming an interlayer insulation film by vapor phase growth at a top surface of the oxide film to locate a top surface of the interlayer insulation film below the top surface of the semiconductor substrate; and forming an upper electrode in contact with the semiconductor substrate at the top surface of the semiconductor substrate and a side surface of the trench located above the top surface of the interlayer insulation film.