Selectively Doped Gate Electrode for TDDB-Reliable Semiconductors
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Solution Overview
Problem
Fabricating semiconductor devices with smaller feature sizes that meet both area scaling and reliability requirements, particularly in high-voltage operations, is challenging due to degradation of the gate dielectric layer caused by peak electric fields leading to time-dependent dielectric breakdown (TDDB) issues.
Innovation Solution
A semiconductor device with a selectively doped gate electrode structure is introduced, where a portion of the gate electrode is selectively doped to change its conductivity type, reducing electron injection into the gate dielectric layer and mitigating electron-hole recombination events, thereby improving TDDB reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a uniformly doped gate electrode structure is used, then the device structure is simple and manufacturing is easier, but the gate dielectric layer degrades under high-voltage conditions due to electron injection and electron-hole recombination, leading to poor TDDB reliability
Solution Approach 1:
The gate electrode is divided into regions with different doping types: a first region with first conductivity type, a second region with second conductivity type, and a third region with first conductivity type. This local differentiation of doping properties allows the gate electrode to reduce electron injection into the gate dielectric layer at critical interfaces while maintaining overall structural functionality, thereby improving TDDB reliability without requiring complete structural redesign
2Reliability
If the gate electrode is selectively doped to improve TDDB reliability, then electron injection into the gate dielectric layer is reduced, but additional processing steps and mask requirements are introduced
Solution Approach 1:
The selective doping of the gate electrode is integrated into the existing source and drain formation process. The same implantation steps used to create source and drain regions are also used to dope the gate electrode regions, combining multiple functions into a single process sequence. This approach achieves the desired doping profile improvement without adding separate dedicated processing steps or additional mask requirements
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 selectively doped gate electrode structure significantly enhances the TDDB characteristics of the gate dielectric layer, extending its reliability under high-voltage conditions without requiring additional processing steps or mask requirements.
Implementation Method 1
reducing electron injection into the gate dielectric layer
Implementation Method 2
mitigating electron-hole recombination events
Data Source
AI summary
Semiconductor devices including selectively doped gate electrodes are described. The semiconductor device comprises a substrate including a body region and a drift region, a gate dielectric layer on the substrate, the gate dielectric layer extending over the body region and the drift region, and a gate dielectric layer on the drift region, the field relief dielectric layer laterally abutting the gate dielectric layer at a location in the drift region. The semiconductor device also includes a gate electrode having an n-doped first portion, a p-doped second portion, and an n-doped third portion. The selectively doped second portion of the gate electrode is located over an intersection between the gate dielectric layer and the field relief dielectric layer.