High-k Gate Insulator Protrusion Control for Threshold Voltage Stability
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Solution Overview
Problem
As semiconductor devices miniaturize, the threshold voltage of n-type MIS transistors increases due to oxygen diffusion into high-dielectric insulating films containing metals like lanthanum, leading to higher threshold voltages as gate width decreases, while p-type MIS transistors experience less significant increases in threshold voltage.
Innovation Solution
The semiconductor device design includes a high-dielectric insulating film with a reduced protrusion amount on the device isolation region, minimizing the contact area and oxygen diffusion, thereby preventing threshold voltage increases in both n-type and p-type MIS transistors as the gate width narrows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the gate width is reduced to miniaturize the semiconductor device, then the device size decreases, but the threshold voltage of n-type MIS transistors increases due to oxygen diffusion into high-dielectric insulating films
Solution Approach 1:
The patent extracts the high-dielectric insulating film from direct contact with the device isolation region by reducing its protrusion amount. This separation removes the source of oxygen diffusion (the high-dielectric film containing metal) from the harmful environment (device isolation region), thereby preventing threshold voltage shifts while maintaining device miniaturization
Solution Approach 2:
The patent introduces a conceptual intermediary relationship where the reduced protrusion amount of the high-dielectric insulating film acts as a buffer zone. This intermediate configuration prevents direct oxygen exchange between the device isolation region and the high-dielectric film, stabilizing threshold voltage without compromising device scaling
2Reliability
If the contact area between high-dielectric insulating film and device isolation region is reduced, then oxygen diffusion is minimized, but the gate insulating film structure becomes more constrained
Solution Approach 1:
The patent changes the geometric parameter of the high-dielectric insulating film by reducing its protrusion amount into the device isolation region. This parameter adjustment directly controls the contact area, minimizing oxygen diffusion pathways while maintaining a relatively simple gate insulating film structure without requiring complex multi-layer configurations
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 configuration effectively stabilizes the threshold voltage of n-type MIS transistors and minimizes slight increases in p-type MIS transistors, even as the semiconductor device size decreases, by reducing oxygen diffusion into the high-dielectric insulating films.
Implementation Method 1
oxygen diffusion into high-dielectric insulating films containing metals like lanthanum
Data Source
AI summary
A semiconductor device according to the present invention has an n-type MIS transistor. The n-type MIS transistor has a first active region surrounded by a device isolation region in a semiconductor substrate, a first gate insulating film having a first high-dielectric-constant insulating film containing a first metal for adjustment, and a first electrode formed on the first gate insulating film. A protrusion amount of one end of the first high-dielectric-constant insulating film on the first device isolation part is smaller than a protrusion amount of an end of the first gate electrode above the first device isolation part.