Diffusion Region Width Control via Ion Implantation
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Solution Overview
Problem
Conventional memory device manufacturing processes result in increased width of diffusion regions near the surface of the semiconductor substrate, known as 'mushrooming', which leads to short circuits and obstacles in reducing the pitch between active areas, especially as semiconductor devices are scaled to smaller dimensions.
Innovation Solution
A method involving the formation of an oxide layer over the semiconductor substrate, ion implantation to create diffusion regions, and a high-temperature annealing process to densify the dielectric and promote grain growth, reducing nucleation and thereby minimizing the increase in width of diffusion regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional manufacturing processes are used to form diffusion regions, then the diffusion regions can be created in the semiconductor substrate, but the width of the diffusion regions increases near the surface (mushrooming effect)
Solution Approach 1:
The method applies preliminary action by performing ion implantation to create damaged regions before the main diffusion process. This pre-damaged layer acts as a barrier that prevents excessive lateral diffusion and mushrooming during subsequent processing steps, thereby controlling the width uniformity of the diffusion regions.
Solution Approach 2:
The invention changes physical parameters by introducing a damaged region through ion implantation with specific energy and dose parameters. This creates a modified material structure that alters the diffusion characteristics, preventing the width increase near the surface while maintaining the desired diffusion depth and concentration.
2Productivity
If the pitch between active areas is reduced to enable smaller device sizes, then device scaling is achieved, but short circuits occur due to the increased diffusion region width
Solution Approach 1:
By creating damaged regions through ion implantation before diffusion, the method establishes a controlled barrier that limits lateral spread of dopants. This enables tighter spacing between active areas while maintaining electrical isolation, thus achieving device scaling without short circuits.
Solution Approach 2:
The damaged region acts as an intermediary layer between the surface and the bulk substrate. This intermediate damaged zone serves as a diffusion barrier that prevents direct lateral expansion of dopants, enabling closer spacing of active areas while maintaining reliability through electrical isolation.
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 method effectively reduces the width increase of diffusion regions by up to 16.5% near the surface, preventing short circuits and enabling tighter packing of active areas, thus addressing the challenge of scaling semiconductor devices to smaller sizes.
Implementation Method 1
forming an oxide over a semiconductor and a gate adjacent to the semiconductor
Implementation Method 2
ions are implanted into at least a portion of the semiconductor through the oxide, forming a plurality of diffusion regions in the semiconductor
Implementation Method 3
the dielectric may be annealed
Data Source
AI summary
Semiconductor devices and methods for forming semiconductor devices are provided, including semiconductor devices that comprise one or more diffusion regions in a semiconductor, the one or more diffusion regions being adjacent to a gate formed adjacent to a surface of the semiconductor (e.g., a semiconductor substrate). The one or more diffusion regions comprise a first width at a depth below the surface of the semiconductor and a second width near the surface of the semiconductor, the second width of the one or more diffusion regions being less than about 40% greater than the first width.