Transistor Recess Insulating Layer Impurity Diffusion Control
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Solution Overview
Problem
Current semiconductor devices face challenges in achieving miniaturization, low power consumption, high performance, and multi-functionality, particularly in memory circuits where transistors with improved characteristics are needed to enhance operating characteristics and reliability.
Innovation Solution
The development of an electronic device with a transistor structure that includes a semiconductor substrate with an active region defined by an isolation layer, a gate structure crossing the active region, recesses on both sides of the gate structure, an insulating layer with a specific top surface curvature, and a junction layer formed over the insulating layer using an epitaxial growth process, which prevents impurity diffusion and improves transistor performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the transistor structure uses conventional planar configuration, then the manufacturing process is simple, but the operating characteristics and reliability are insufficient for miniaturization and high performance requirements
Solution Approach 1:
The transistor structure is divided into multiple functional regions including source region, drain region, channel region, and gate structure. The recesses are segmented into first recesses and second recesses with different depths and positions, allowing independent optimization of each region's properties to improve overall reliability while managing complexity through functional segmentation.
Solution Approach 2:
Different regions of the transistor are given different local properties: the first recesses have specific depths to control impurity concentration in source/drain regions, the second recesses have different depths to control channel doping, and the gate structure has specific dimensions to optimize field effect. This local quality approach allows each region to be optimized for its specific function, improving reliability without requiring complete structural redesign.
2Reliability
If impurity concentration in junction layer is increased to improve transistor performance, then operating characteristics improve, but impurity diffusion into channel increases causing reliability degradation
Solution Approach 1:
An insulating layer is introduced as an intermediary barrier between the junction layer (source/drain regions with high impurity concentration) and the channel region. This insulating layer prevents direct diffusion of impurities from the junction layer into the channel while allowing the junction layer to maintain high impurity concentration for improved transistor operating characteristics such as higher drive current and better switching performance.
Solution Approach 2:
The harmful impurity diffusion pathway is extracted or removed from the system by introducing the insulating layer that blocks the diffusion path. This separates the impurity-containing junction layer from the channel region, allowing the beneficial high impurity concentration to be maintained in the junction layer while the harmful diffusion effect is eliminated.
3Productivity
If device miniaturization is pursued to increase integration density, then more devices fit on chip, but manufacturing precision and reliability become more difficult to maintain
Solution Approach 1:
The transistor structure transitions from a conventional planar two-dimensional configuration to a three-dimensional structure with recesses at different depths. The first recesses and second recesses are positioned at different vertical levels, creating a multi-layered architecture that increases functional density without proportionally increasing lateral dimensions. This dimensional approach allows higher integration density while maintaining manufacturable feature sizes and tolerances.
Solution Approach 2:
The transistor structure employs nested regions where the second recesses are positioned within or adjacent to the first recesses at different depths. The gate structure is nested within the semiconductor substrate, and the insulating layer is nested within the recesses. This nesting approach maximizes the use of available space, allowing multiple functional elements to be packed into a smaller overall footprint, thereby increasing integration density while maintaining manufacturing precision through hierarchical structuring.
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 enhances the operating characteristics and reliability of transistors by maintaining high impurity concentration in the junction layer, reducing interface resistance, and preventing impurity diffusion into the channel, thereby improving the performance of semiconductor memory devices.
Implementation Method 1
The insulating layer prevents the impurities from diffusing into a channel of the transistor
Implementation Method 2
a junction layer disposed over the insulating layer in the first recess in the third direction
Data Source
AI summary
An electronic device includes a transistor. The transistor includes: a substrate including an active region that extends in a first direction; a gate structure disposed in the substrate and crossing the active region in a second direction that crosses the first direction; recesses disposed in the active region on two sides of the gate structure in the first direction, a center of a bottom surface of a first recess being more depressed in a third direction than two edges of the bottom surface along the first direction, the third direction being perpendicular to the first and second directions; an insulating layer disposed in the first recess; and a junction layer disposed over the insulating layer in the first recess in the third direction, a top surface of the insulating layer being below the two edges of the bottom surface and having a smaller curvature than the bottom surface.