Strain-Inducing Buffer Conversion to Electrical Insulator
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Solution Overview
Problem
Semiconductor buffer layers, used to inhibit misfit dislocations and induce strain in neighboring layers, pose integration and device issues due to their parasitic nature, causing sub-Fin leakage and other integration challenges if left behind during the fabrication of integrated circuits.
Innovation Solution
A methodology to convert a strain-inducing semiconductor buffer layer into an electrical insulator at specific locations, allowing the device layer to be electrically isolated from the substrate while maintaining the desired strain, thereby eliminating substrate junction leakage and reducing misfit dislocations, using techniques such as under-Fin oxidation (UFO) processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a strain-inducing semiconductor buffer layer is used to inhibit misfit dislocations and induce strain in neighboring layers, then the quality of the device layer is improved, but the buffer layer causes parasitic effects including sub-Fin leakage and integration challenges
Solution Approach 1:
The buffer layer is segmented into two functional regions: a first portion that maintains strain-inducing properties for the device layer, and a second portion converted to electrical insulator material that eliminates parasitic leakage paths. This segmentation allows the buffer to simultaneously provide mechanical strain support while blocking electrical leakage.
Solution Approach 2:
The electrical properties of the buffer layer are changed by converting it from a semiconductor material (conductive) to an insulator material (non-conductive). This parameter change in electrical conductivity eliminates the parasitic leakage while the strain-inducing portion maintains its mechanical properties for device layer quality.
2Object-generated harmful factors
If the buffer layer is completely removed, then parasitic leakage is eliminated, but strain induction capability is lost
Solution Approach 1:
Rather than completely removing the buffer layer, the invention segments it into functional portions: the first portion under the device layer is retained to maintain strain induction, while the second portion is converted to insulator to eliminate leakage. This selective retention through segmentation solves both requirements.
Solution Approach 2:
Different portions of the buffer layer are given different properties: the region requiring strain induction maintains semiconductor characteristics, while regions requiring leakage blocking are converted to insulator material. This local differentiation of material properties resolves the contradiction between maintaining strain and eliminating parasitics.
3Object-generated harmful factors
If the buffer layer is converted to electrical insulator, then junction leakage is reduced, but the strain-inducing capability may be compromised
Solution Approach 1:
The buffer layer is divided into a first portion that maintains strain-inducing semiconductor properties and a second portion converted to insulator material. This segmentation ensures that strain induction capability is preserved in the critical region while leakage blocking is achieved in the converted region.
Solution Approach 2:
The buffer layer structure is designed to perform multiple functions simultaneously: the first portion provides strain induction, while the second portion provides electrical insulation. This multi-functionality allows a single buffer structure to address both strain maintenance and leakage elimination requirements.
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 conversion of buffer layers to electrical insulators significantly reduces junction leakage, maintains device performance, and allows for the use of strained device layers with low misfit dislocations, enhancing the quality of integrated circuits and reducing integration complexities.
Implementation Method 1
converting at least one of the buffer regions below the semiconductor bodies to an electrical insulator
Data Source
AI summary
Techniques are disclosed for converting a strain-inducing semiconductor buffer layer into an electrical insulator at one or more locations of the buffer layer, thereby allowing an above device layer to have a number of benefits, which in some embodiments include those that arise from being grown on a strain-inducing buffer and having a buried electrical insulator layer. For instance, having a buried electrical insulator layer (initially used as a strain-inducing buffer during fabrication of the above active device layer) between the Fin and substrate of a non-planar integrated transistor circuit may simultaneously enable a low-doped Fin with high mobility, desirable device electrostatics and elimination or otherwise reduction of substrate junction leakage. Also, the presence of such an electrical insulator under the source and drain regions may further significantly reduce junction leakage. In some embodiments, substantially the entire buffer layer is converted to an electrical insulator.