Amorphous-Polycrystalline Silicon Channel for Leakage Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Semiconductor devices using polysilicon (poly-Si) as the channel material face challenges in suppressing leakage current due to residual metal trapped at the interface vicinity, which affects mobility and increases the threshold voltage, making it difficult to maintain low grain boundaries and large particle sizes within the channel layer.
Innovation Solution
The semiconductor device incorporates an amorphous region at the lower portion of the channel layer, which increases resistance and suppresses conduction caused by residual metal, achieved through a process involving metal-induced lateral crystallization (MILC) and oblique ion implantation to amorphize the poly-Si layer, thereby reducing leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If polysilicon is used as the channel material, then the device can achieve three-dimensional memory and stacked circuits, but residual metal trapped at the interface vicinity increases leakage current and reduces reliability
Solution Approach 1:
The channel layer is divided into two distinct regions: a lower portion with larger particle size (first region) and an upper portion with smaller particle size (second region). This segmentation allows each region to serve different functions - the lower region suppresses leakage current while the upper region maintains carrier mobility, thus resolving the contradiction between reliability and productivity
Solution Approach 2:
Different regions of the channel layer are given different local properties - the lower portion has larger particles and higher resistance characteristics for leakage suppression, while the upper portion has smaller particles for maintaining conductivity. This local differentiation enables simultaneous achievement of low leakage and high productivity
2Reliability
If the channel layer has large particle size and low grain boundaries, then carrier mobility is improved, but residual metal at the interface increases threshold voltage and causes leakage
Solution Approach 1:
The channel layer is segmented into a lower portion with large particles for low leakage and an upper portion with small particles for high mobility. This segmentation spatially separates the functions of leakage suppression and mobility enhancement, resolving the contradiction between reducing harmful effects and maintaining useful properties
Solution Approach 2:
The invention applies different local qualities to different regions - the lower portion has large particle size for suppressing leakage current, while the upper portion has small particle size for maintaining carrier mobility. This local quality differentiation allows the device to simultaneously achieve low threshold voltage and high mobility
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 suppresses leakage current and enhances the mobility of carriers by increasing the resistance of the channel layer, improving the crystallinity and reducing the impact of residual metal trapped at the interface, resulting in a semiconductor device with improved performance.
Implementation Method 1
The amorphous region in the lower portion of the channel layer increases resistance and suppresses conduction caused by residual metal
Implementation Method 2
achieved through a process involving metal-induced lateral crystallization (MILC)
Implementation Method 3
achieved through a process involving metal-induced lateral crystallization (MILC) and oblique ion implantation to amorphize the poly-Si layer
Data Source
AI summary
According to one embodiment, a semiconductor device includes first to third semiconductor regions and first to third conductors. The second semiconductor region is separated from the first semiconductor region in a first direction. The third semiconductor region is provided between the first and the second semiconductor regions. The third conductor is separated from the third semiconductor region in a second direction intersecting the first direction. The third semiconductor region includes first and second partial regions. The first partial region includes a first metal element, and is amorphous. The second partial region is stacked with the first partial region in the second direction, and is polycrystalline. A first concentration of the first metal element in the first partial region is higher than a second concentration of the first metal element in the second partial region, or the second partial region does not include the first metal element.