Laser-Formed Single Crystalline Film for SOI Substrates
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
As integration densities of semiconductor devices using silicon-on-insulator (SOI) substrates increase, the accumulation of holes in these substrates leads to undesirable effects such as decreased threshold voltage and increased drain current in transistors, primarily due to the floating body effect.
Innovation Solution
A method of fabricating silicon-on-insulator substrates involves forming a single crystalline structure on a semiconductor substrate, creating openings in insulating films, and using laser beams to convert non-single crystalline films into single crystalline films with the same structure as the substrate, thereby reducing hole accumulation and improving transistor performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If integration density of semiconductor devices is increased, then device capacity and functionality are improved, but hole accumulation in SOI substrates increases causing decreased threshold voltage and increased drain current
Solution Approach 1:
The patent extracts and removes holes from the bulk substrate region between transistors by forming contact holes through the insulating film and etching away the bulk substrate material. This extraction of harmful charge carriers (holes) prevents the floating body effect and maintains stable transistor threshold voltages, allowing high integration density without sacrificing device reliability
Solution Approach 2:
The patent introduces an intermediary structure - a conductive material filled in contact holes that extends from the surface through the insulating film to the bulk substrate. This intermediary conductive path provides a controlled mechanism to remove holes from the substrate while maintaining precise control over the transistor operation, enabling stable performance at high integration densities
2Ease of manufacture
If conventional SOI substrate fabrication is used, then manufacturing process is simple, but hole accumulation causes floating body effect and kink effect
Solution Approach 1:
The patent segments the substrate structure by introducing contact holes that divide the bulk substrate into accessible regions. By segmenting the otherwise continuous bulk substrate, holes can be selectively removed from specific regions between transistors, eliminating the floating body effect while maintaining the simplicity of SOI fabrication processes
Solution Approach 2:
The patent creates a porous or penetrable structure in the bulk substrate by forming contact holes filled with conductive material. This porous approach allows controlled access to and removal of holes from the substrate, preventing harmful charge accumulation while adding minimal complexity to the manufacturing process
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 reduces defects and undesirable effects in transistors by ensuring the single crystalline lattice structure across the substrate, enhancing operational characteristics by preventing hole accumulation and maintaining the potential barrier, thus improving the overall performance of semiconductor devices.
Implementation Method 1
A laser beam is generated that heats the first non-single crystalline film to change the first non-single crystalline film into a first single crystalline film
Data Source
AI summary
In some methods of fabricating a silicon-on-insulator substrate, a semiconductor substrate is provided that includes a single crystalline structure within at least a defined region thereof. A first insulating film is formed on the defined region of the semiconductor substrate with an opening that exposes a portion of the defined region of the semiconductor substrate having the single crystalline structure. A first non-single crystalline film is formed on the exposed portion of the semiconductor substrate and that at least substantially fills the opening in the first insulating film. A laser beam is generated that heats the first non-single crystalline film to change the first non-single crystalline film into a first single crystalline film having substantially the same single crystalline structure as the defined region of the semiconductor substrate.