FDSOI Bulk Silicon Backfill Doping for Leakage Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
FDSOI devices experience abnormal off-current leakage due to the use of intrinsic silicon in the silicon backfill technology, leading to diffusion issues and uncontrollable doping during subsequent processes, which affects the performance and reliability of devices like LDMOS.
Innovation Solution
A method involving the formation of a semiconductor structure with a bulk silicon region, where a recess is etched and filled with monocrystalline silicon, followed by shallow trench isolation and ion implantation, to optimize the doping condition and reduce leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If intrinsic silicon is used in silicon backfill technology, then the fabrication process is simplified, but abnormal off-current leakage occurs due to diffusion and uncontrollable doping
Solution Approach 1:
The patent removes the problematic intrinsic silicon backfill material and replaces it with a recess structure filled with doped silicon or semiconductor material. This extraction eliminates the source of abnormal leakage while maintaining the structural support function, directly resolving the contradiction between manufacturing simplicity and device reliability.
Solution Approach 2:
The patent changes the material parameter from intrinsic silicon to doped silicon or semiconductor material with controlled electrical properties. By adjusting the doping concentration and type, the patent achieves controlled electrical characteristics that prevent abnormal leakage while maintaining ease of fabrication through standard semiconductor processing techniques.
2Reliability
If FDSOI structure is used to reduce short-channel effect, then device performance is improved, but abnormal off-current leakage occurs in bulk silicon region
Solution Approach 1:
The patent segments the silicon substrate into distinct regions: the FDSOI active device region and the bulk silicon backfill region. By creating a recess in the bulk silicon region and filling it with controlled doped material, the patent isolates the harmful leakage effects from the active FDSOI devices while maintaining the structural integrity and short-channel effect benefits of the FDSOI structure.
Solution Approach 2:
The patent applies different material properties to different regions: the FDSOI region maintains its intrinsic properties for optimal device performance, while the bulk silicon backfill region is modified with controlled doping to eliminate leakage. This local differentiation resolves the contradiction by allowing each region to have the properties needed for its specific function.
3Ease of manufacture
If metal gate-last technology is adopted for compatibility, then process integration is improved, but height difference in bulk silicon region causes leakage
Solution Approach 1:
The patent performs preliminary action by creating the recess structure and filling it with doped silicon or semiconductor material before completing the metal gate-last process. This preliminary structuring of the bulk silicon region eliminates height differences that would cause leakage, while still allowing the metal gate-last technology to be implemented for process compatibility.
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 significantly reduces leakage current by 5 orders of magnitude, improving the performance and reliability of FDSOI devices by controlling the doping condition in the bulk silicon region.
Implementation Method 1
forming a recess area in the bulk silicon region by removing the silicon nitride layer, the first oxide layer, the SOI layer, and the buried oxide layer in the bulk silicon region by etch
Implementation Method 2
performing ion implantation on the bulk silicon region
Data Source
AI summary
The present disclosure provides a method for improving an FDSOI device leakage, including steps of: defining a bulk silicon region on the semiconductor structure, and forming an recess area by removing a silicon nitride layer, a first oxide layer, an SOI layer, and a buried oxide layer in the bulk silicon region by etch, wherein the etch is stopped at the silicon substrate; refilling the recess area in the bulk silicon region with monocrystalline silicon, until the monocrystalline silicon reaches a same height as that of the SOI layer outside of the bulk silicon region; forming an STI region, and performing ion implantation on the bulk silicon region; and forming a device structure in the bulk silicon region. In the present disclosure, a doping condition for the bulk silicon region is selected to meet the demands of the device, thereby solving the problem of the device leakage.