Bonded SOI Substrate Formation Beyond Ion Implantation Thickness Limits
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Solution Overview
Problem
Current methods for forming semiconductor-on-insulator (SOI) substrates are limited by the small thicknesses of the device and insulator layers, which restrict their use in applications requiring large semiconductor junctions and low leakage current, such as high-voltage devices and CMOS image sensors, due to the limitations of ion implantation techniques.
Innovation Solution
The method involves forming an insulator layer fully covering a handle substrate and epitaxially growing a device layer on a sacrificial substrate, which is then bonded to the handle substrate and the sacrificial substrate is removed, allowing for the formation of thick device and insulator layers without the thickness restrictions of traditional ion implantation methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ion implantation techniques are used to form SOI substrates, then the manufacturing process is simple and well-established, but the device and insulator layer thicknesses are limited to small values
Solution Approach 1:
The patent changes the fundamental parameter of layer formation from ion implantation (which limits thickness) to epitaxial growth (which enables thick layers). By epitaxially growing the device layer on a sacrificial substrate and the insulator layer on the handle substrate, then bonding them together, the method achieves thick device layers (e.g., 5-20 micrometers) and thick insulator layers (e.g., 1-10 micrometers) that are incompatible with traditional ion implantation techniques.
Solution Approach 2:
The patent introduces a sacrificial substrate as an intermediary component that enables the formation of thick device layers. The sacrificial substrate serves as a temporary carrier for epitaxial growth, allowing thick device layers to be formed and then transferred to the handle substrate through bonding. This intermediary approach resolves the contradiction by enabling thick layer formation without the thickness limitations of direct ion implantation.
2Adaptability or versatility
If thick device layers are formed to enable large semiconductor junctions, then applicability to high-voltage devices improves, but traditional ion implantation methods cannot achieve the required thickness
Solution Approach 1:
The patent fundamentally changes the layer formation parameter from ion implantation depth (micrometer scale limited) to epitaxial growth thickness (tens of micrometers achievable). This parameter change enables the formation of thick device layers required for large semiconductor junctions in high-voltage devices, directly resolving the contradiction between thickness requirement and manufacturing capability.
3Reliability
If thick insulator layers are formed to reduce leakage current, then performance in demanding applications improves, but ion implantation techniques limit insulator layer thickness
Solution Approach 1:
The patent changes the insulator layer formation method from ion implantation (which creates amorphous layers with thickness limits) to epitaxial growth (which creates crystalline layers with superior properties and no practical thickness limits). This enables formation of thick insulator layers (e.g., 1-10 micrometers) that provide excellent leakage current reduction while maintaining manufacturing precision through controlled epitaxial growth processes.
4Ease of manufacture
If the sacrificial substrate is removed by etching, then the device layer is released onto the handle substrate, but arcing during plasma processing may occur on the handle substrate
Solution Approach 1:
The patent applies preliminary anti-action by forming a protective coating on the handle substrate before the sacrificial substrate removal process. This coating prevents arcing during plasma etching by providing a dielectric barrier that protects the handle substrate from plasma discharge. The coating is applied in advance, preventing the harmful effect of arcing before it can occur, while still allowing the etching process to successfully remove the sacrificial substrate and release the device layer.
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 enables the creation of SOI substrates with thick device and insulator layers, facilitating the formation of large semiconductor junctions and reducing leakage current, thereby expanding their applicability to high-voltage and other demanding applications while maintaining low total thickness variation and preventing arcing during plasma processing.
Implementation Method 1
a device substrate is oxidized to form an oxide layer surrounding the device substrate
Implementation Method 2
Hydrogen ions are implanted into the device substrate to form a hydrogen-rich region buried in the device substrate
Data Source
AI summary
Various embodiments of the present application are directed towards a method for forming a semiconductor-on-insulator (SOI) substrate with a thick device layer and a thick insulator layer. In some embodiments, the method includes forming an insulator layer covering a handle substrate, and epitaxially forming a device layer on a sacrificial substrate. The sacrificial substrate is bonded to a handle substrate, such that the device layer and the insulator layer are between the sacrificial and handle substrates, and the sacrificial substrate is removed. The removal includes performing an etch into the sacrificial substrate until the device layer is reached. Because the device layer is formed by epitaxy and transferred to the handle substrate, the device layer may be formed with a large thickness. Further, because the epitaxy is not affected by the thickness of the insulator layer, the insulator layer may be formed with a large thickness.