SOI Substrate Transfer Process for Thick Device and Insulator Layers
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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 and CMOS devices, due to limitations in 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 transferred and bonded to the handle substrate, allowing for the formation of thick device and insulator layers with controlled thickness variations, enabling the use of SOI substrates in high-voltage and other advanced applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If ion implantation techniques are used to form SOI substrates, then the manufacturing process is simple and direct, but the device and insulator layer thicknesses are limited to small values
Solution Approach 1:
The manufacturing process is divided into multiple independent stages: forming the insulator layer on the handle substrate, separately forming the device layer on a sacrificial substrate, and then bonding them together. This segmentation allows each layer to be optimized independently, enabling thick device layers (e.g., 1-10 micrometers) and thick insulator layers to be achieved without the thickness limitations of direct ion implantation methods.
Solution Approach 2:
The device layer is preliminarily formed on a sacrificial substrate with controlled thickness before bonding to the handle substrate. This preliminary formation allows precise thickness control of the device layer (e.g., 1-10 micrometers) through controlled epitaxial growth or other deposition techniques, overcoming the small thickness limitations of ion implantation while maintaining manufacturing feasibility.
2Adaptability or versatility
If thick device layers are formed to enable large semiconductor junctions, then high-voltage and advanced applications become possible, but traditional ion implantation methods cannot achieve the required thickness
Solution Approach 1:
By separating the formation of the device layer from the final SOI structure assembly, the method enables thick device layers (e.g., 1-10 micrometers) to be created on a sacrificial substrate using controlled epitaxial growth or deposition. This segmentation allows the device layer to achieve the necessary thickness for large semiconductor junctions in high-voltage applications, which is impossible with direct ion implantation methods.
Solution Approach 2:
A sacrificial substrate is introduced as an intermediary carrier to form the thick device layer. This intermediary allows precise thickness control during the formation process, and the sacrificial substrate is later removed through selective etching to release the thick device layer for bonding to the handle substrate, enabling application ranges that include high-voltage and advanced semiconductor devices.
3Reliability
If thick insulator layers are formed to reduce leakage current, then performance in high-voltage applications improves, but ion implantation limitations prevent achieving sufficient thickness
Solution Approach 1:
The insulator layer is formed independently on the handle substrate before bonding the device layer assembly. This segmentation allows the insulator layer to be grown to sufficient thickness (e.g., 0.5-5 micrometers) using thermal oxidation or chemical vapor deposition, achieving the necessary thickness for low leakage current in high-voltage applications, which cannot be achieved through ion implantation alone.
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 allows for the creation of SOI substrates with thick device and insulator layers, enhancing their suitability for high-voltage and other advanced applications by reducing leakage current and enabling the formation of large semiconductor junctions, thus overcoming the limitations of traditional methods.
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
Implementation Method 3
The device substrate is bonded to a handle substrate through the oxide layer
Implementation Method 4
the device substrate is split along the hydrogen-rich region to partially remove a portion of the oxide layer and a portion of the device substrate from the handle substrate
Implementation Method 5
A chemical mechanical polish (CMP) is performed into a portion of the device substrate remaining on the handle substrate to flatten the remaining portion
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.