Stripe Trench Gate Semiconductor Device with Graded Dielectric
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Solution Overview
Problem
Power semiconductor devices, such as IGFETs, face challenges in reliability due to the limitations of existing gate dielectric structures, which affect the performance and durability of the devices, especially in active and idle regions.
Innovation Solution
The semiconductor device incorporates a stripe-shaped trench gate structure with a gate dielectric that has thinner sections in active regions and thicker sections in idle regions, enhancing the reliability by reducing the effective field and increasing the threshold voltage, thereby improving electric separation and device reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a uniform gate dielectric structure is used, then the manufacturing process is simple, but the reliability is reduced due to high electric field stress in idle regions
Solution Approach 1:
The gate dielectric structure employs different thicknesses in different regions: a first thickness in active sections and a second, greater thickness in idle sections. This local differentiation allows the idle sections to have enhanced breakdown voltage and reduced electric field stress, improving reliability without affecting the performance of active regions.
Solution Approach 2:
The gate dielectric is segmented into multiple sections with different thicknesses along the gate electrode length. The idle sections are divided into first, second, and third sections with progressively different dielectric thicknesses, creating a graded structure that optimizes both reliability and performance.
2Reliability
If the gate dielectric is made thicker to improve reliability, then the breakdown voltage increases, but the threshold voltage control and transistor performance deteriorate
Solution Approach 1:
Different regions of the gate dielectric have different thicknesses optimized for their specific functions: thinner dielectric in active sections for good threshold voltage control and high performance, thicker dielectric in idle sections for high breakdown voltage and reliability. This local optimization resolves the contradiction between performance and reliability.
Solution Approach 2:
The gate dielectric is segmented into multiple sections with different thicknesses: a first section with thinner dielectric for performance-critical areas and second/third sections with thicker dielectric for reliability-critical areas. This segmentation allows simultaneous optimization of both threshold voltage control and breakdown voltage.
3Reliability
If a thicker gate dielectric is used in idle sections, then the electric field stress is reduced and reliability improves, but the manufacturing precision requirements increase
Solution Approach 1:
The gate dielectric is formed as a segmented structure with different thicknesses in different sections. The idle sections are divided into multiple sub-sections (first, second, third sections) with progressively different thicknesses, allowing precise control of electric field distribution while maintaining manufacturability through standard semiconductor fabrication techniques.
Data Source
AI summary
A semiconductor device includes a transistor cell with a stripe-shaped trench gate structure that extends from a first surface into a semiconductor body. A gate connector structure at a distance to the first surface is electrically connected to a gate electrode in the trench gate structure. A gate dielectric separates the gate electrode from the semiconductor body. First sections of the gate dielectric outside a vertical projection of the gate connector structure are thinner than second sections within the vertical projection of the gate connector structure.