Recess Gate MOSFET Structure With Metallic Insertion for Higher On-Current
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Solution Overview
Problem
The challenge in semiconductor device manufacturing lies in increasing on-current characteristics while reducing external parasitic resistance and process difficulties associated with scaling down MOSFET devices, particularly in recess gate structures, where high concentration doping is limited by solubility and diffusivity of dopants and can introduce defects.
Innovation Solution
A semiconductor device with a recess gate structure that incorporates a metallic insertion layer between the gate insulating layer and the insulating capping layer, which increases effective doping concentration through a charge-plasma effect, enhancing on-current without high concentration doping, and includes a method for manufacturing this device with specific layer formations and materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high concentration doping is applied to source/drain regions to reduce external parasitic resistance, then contact resistance decreases, but doping concentration is limited by solubility and diffusivity of dopants
Solution Approach 1:
A metallic insertion layer is introduced between the gate insulating layer and the source/drain regions. This metallic layer acts as an intermediary that modifies the energy band structure of the semiconductor, effectively increasing the doping concentration without requiring high concentration dopant diffusion. The metallic layer mediates the electrical characteristics, achieving low contact resistance while avoiding the solubility and diffusivity limitations of traditional doping methods.
Solution Approach 2:
The invention changes the physical and chemical parameters of the source/drain regions by introducing the metallic insertion layer. This layer alters the energy band structure and effective doping concentration through physical presence rather than chemical doping. By changing the material composition and structural parameters, the invention achieves high effective doping concentration without being constrained by dopant solubility limits.
2Reliability
If high concentration doping is applied to reduce external parasitic resistance, then on-state current performance improves, but defects in inter-device deviation increase
Solution Approach 1:
The metallic insertion layer serves as a mediator that uniformly modifies the electrical characteristics across all devices. Instead of relying on high concentration doping which causes random dopant fluctuation and inter-device variation, the metallic layer provides a consistent energy band modification effect, thereby improving on-state current while maintaining uniformity and reducing manufacturing precision issues.
3Reliability
If high concentration doping is applied to reduce external parasitic resistance, then contact resistance decreases, but subsequent high temperature-heat treatment processing is required
Solution Approach 1:
The metallic insertion layer achieves the desired electrical characteristics through its inherent material properties and energy band structure modification. This eliminates the need for subsequent high temperature-heat treatment steps that would be required after high concentration doping to activate dopants and repair damage. The metallic layer provides immediate electrical improvement without additional complex processing.
4Productivity
If recess gate structure is applied to overcome short channel effect, then device scaling is enabled, but external parasitic resistance increases
Solution Approach 1:
The metallic insertion layer is locally positioned at the interface between the gate insulating layer and the source/drain regions. This local modification of the energy band structure at the critical interface region effectively reduces parasitic resistance without changing the overall recess gate structure that enables scaling. The local quality change at the interface compensates for the scaling-induced parasitic resistance increase.
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 effectively increases on-current and reduces variations between devices, overcoming limitations in high concentration doping processes, maintaining operational characteristics at low applied voltages, and reducing defect rates and power consumption.
Implementation Method 1
the metallic insertion layer is configured to increase an effective doping concentration of the semiconductor region by changing an energy band of the source or the drain region
Data Source
AI summary
A semiconductor device and a method of manufacturing the same. The semiconductor device has a substrate in which recess regions are formed and semiconductor regions acting as a source region or a drain region is defined between the recess regions; a gate insulating layer disposed on an inner surface of each recess region; a recess gate disposed on the gate insulating layer in each recess region; an insulating capping layer disposed above the recess gate in each recess region; a metallic insertion layer disposed between a side surface of the recess gate and a side surface of the insulating capping layer and facing with a side surface of the source region or the drain region; and an intermediate insulating layer disposed between the metallic insertion layer and the recess gate to electrically insulate the metallic insertion layer from the recess gate.