Diffusion Barrier Layer in LDMOS for Short-Channel Effect
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Solution Overview
Problem
Current semiconductor structures, particularly LDMOS devices, suffer from poor electrical performance due to the short-channel effect caused by doping ions in the drain region diffusing into the channel region, leading to a depletion layer expansion and reduced carrier mobility.
Innovation Solution
A semiconductor structure with a diffusion barrier layer located between the drain region and the gate structure, preventing doping ions from diffusing into the channel region, thereby alleviating the short-channel effect and improving electrical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If doping ions are introduced into the drain region to improve electrical performance, then carrier concentration in the drain region increases, but doping ions diffuse into the channel region causing depletion layer expansion and short-channel effect
Solution Approach 1:
A diffusion barrier layer is introduced as an intermediary between the drain region and the channel region. This barrier layer selectively blocks doping ions from diffusing into the channel region while allowing electrical signals to pass through, thus preventing the harmful effect of doping ion diffusion without compromising the electrical performance improvement achieved by drain region doping.
Solution Approach 2:
The semiconductor structure is segmented into distinct regions with different functional properties: a drain region for carrier injection, a diffusion barrier layer for ion blocking, and a channel region for current conduction. This segmentation allows each region to be optimized independently, enabling high doping concentration in the drain region while protecting the channel region from doping contamination.
2Productivity
If the channel length is reduced to improve device integration, then device density increases, but the short-channel effect becomes more severe due to easier doping ion diffusion
Solution Approach 1:
The diffusion barrier layer serves as a protective intermediary that enables short channel lengths without suffering from severe short-channel effects. By blocking doping ion diffusion, the barrier layer maintains channel region purity even when the channel length is reduced, allowing higher device integration while preserving transistor performance and reliability.
3Reliability
If high doping concentration is used in the drain region to reduce on-resistance, then electrical conductivity improves, but doping ions diffuse into the channel region causing depletion layer expansion
Solution Approach 1:
The diffusion barrier layer acts as a mediator that allows high doping concentration in the drain region to achieve low on-resistance while preventing the resulting doping ions from diffusing into the channel region. This maintains a narrow depletion layer width and prevents short-channel effects, enabling simultaneous optimization of both on-resistance and device performance.
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 diffusion barrier layer effectively prevents doping ions from diffusing into the channel region, reducing depletion layer expansion and enhancing carrier mobility, thus improving the overall electrical performance of the semiconductor structure.
Implementation Method 1
a diffusion barrier layer, located in the drift region between the drain region and the gate structure, where the diffusion barrier layer is configured to prevent doping ions in the drain region from diffusing into a channel region below the gate structure
Data Source
AI summary
A semiconductor structure and a forming method thereof are provided. One form of the forming method includes: providing a base, where a well region and a drift region adjacent to the well region are formed in the base; forming a trench in the drift region; forming a diffusion barrier layer in the trench; after the diffusion barrier layer is formed, forming a gate structure on the base at a junction between the well region and the drift region, where the gate structure is located on a side of the diffusion barrier layer near the well region; and forming a source region in the well region on one side of the gate structure, and forming a drain region in the drift region on the other side of the gate structure, where the drain region is located on a side of the diffusion barrier layer in the drift region away from the well region. In embodiments and implementations of the present disclosure, during the operation of the semiconductor structure, under the barrier action of the diffusion barrier layer, doping ions in the drain region do not easily diffuse into the channel region below the gate structure, which makes a depletion layer of the source region and the drain region on two sides of the gate structure not easily expand, thereby being beneficial to alleviate the short-channel effect, and further improving the electrical performance of the semiconductor structure.