Semiconductor Device LOCOS STI Isolation Layout
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Solution Overview
Problem
Semiconductor devices with MISFETs face challenges in achieving both improved performance and reduced size, as existing technologies struggle with hot carrier generation due to electric field concentration at sharp corners of isolation films, leading to gate insulating film deterioration and reliability issues.
Innovation Solution
A semiconductor device design incorporating both LOCOS oxide films and STI insulating films, where the LOCOS oxide film is on the side of the channel formation region and the STI insulating film is on the side of the drain region, mitigates electric field concentration and hot carrier generation by using rounded edges for the LOCOS oxide film and separating the STI insulating film from the gate insulating film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single type of isolation film is used, then the device structure is simple, but electric field concentration occurs at sharp corners leading to hot carrier generation and gate insulating film deterioration
Solution Approach 1:
The isolation film is divided into two distinct segments: a first isolation film with a first dielectric constant and a second isolation film with a second dielectric constant. This segmentation allows each segment to perform different functions - the first isolation film reduces electric field concentration at corners, while the second isolation film provides standard isolation, thereby improving gate insulating film reliability without excessive complexity
Solution Approach 2:
Different regions of the isolation film structure are assigned different dielectric properties. The first isolation film is positioned specifically at corners where electric field concentration occurs, while the second isolation film is positioned in other regions. This local quality approach addresses the specific problem of corner electric field concentration without modifying the entire isolation film structure
2Area of moving object
If device size is reduced, then integration density improves, but performance may deteriorate due to increased electric field concentration in smaller structures
Solution Approach 1:
The dielectric constant parameter is changed in specific regions by using a first isolation film with a first dielectric constant and a second isolation film with a second dielectric constant. This parameter change allows the device to maintain smaller dimensions while controlling electric field distribution, thereby preserving performance reliability in miniaturized structures
3Reliability
If performance is improved through larger device structures, then reliability increases, but device size increases reducing integration density
Solution Approach 1:
Instead of uniformly increasing device dimensions to improve performance, the invention applies local quality by positioning a first isolation film with specific dielectric properties at critical corners. This localized approach improves device performance and reduces electric field concentration without requiring overall device size increase, maintaining high integration density
Data Source
AI summary
To provide a semiconductor device having improved performances. A semiconductor substrate has, in the surface layer portion thereof, an n+ type semiconductor region for source and an n+ type semiconductor region for drain separated from each other. The semiconductor substrate has, on the main surface thereof between the n+ type semiconductor region for source and the n+ type semiconductor region for drain, a gate electrode via an insulating film as a gate insulating film. The semiconductor substrate has, in the main surface thereof between the channel formation region below the gate electrode and the n+ type semiconductor region for drain, a LOCOS oxide film and an STI insulating. Of the LOCOS oxide film and the STI insulating film, the LOCOS oxide film is located on the side of the channel formation region and the STI insulating film is on the side of the n+ type semiconductor region DR for drain.