Sacrificial Layer Transfer for Semiconductor On Insulator Structures
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Solution Overview
Problem
Current methods for producing semiconductor-on-insulator (SOI) structures are costly, time-consuming, and suffer from variations in flatness and sensitivity to defects at the bond interface, with traditional SOI structures having electrical characteristics that are difficult to integrate into devices.
Innovation Solution
A method involving the bonding of a handle semiconductor oxide layer with a donor semiconductor nitride layer, using a multilayer dielectric structure comprising oxide-nitride-oxide (ONO) layers to facilitate layer transfer and reduce costs, while ensuring the integrity of the semiconductor device layer by using a cleave plane and plasma treatments to enhance bonding and etching processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional wafer bonding and back etching methods are used to produce SOI structures, then layer transfer can be achieved, but the process becomes time-consuming and costly with poor thickness uniformity
Solution Approach 1:
A cleave plane is formed in the donor substrate before bonding occurs, allowing the layer to be transferred more efficiently. This preliminary preparation enables subsequent rapid separation along the predetermined cleave plane, avoiding time-consuming back etching processes while maintaining good thickness uniformity
Solution Approach 2:
The patent extracts and removes a sacrificial oxide layer that was deposited between the handle substrate and donor substrate. This sacrificial layer is selectively removed through chemical etching, enabling clean layer transfer without requiring extensive back etching of the donor substrate, thus reducing production time while maintaining precision
2Reliability
If hydrogen implantation and thermal annealing are used for layer transfer, then bonding can be achieved, but the process is complex and requires high temperatures
Solution Approach 1:
A sacrificial oxide layer is introduced as an intermediary between the handle substrate and donor substrate. This sacrificial layer facilitates bonding and subsequent layer transfer through selective chemical etching, eliminating the need for complex hydrogen implantation and high-temperature thermal annealing processes while maintaining reliable bond strength
Solution Approach 2:
The patent replaces mechanical and thermal processes (hydrogen implantation and thermal annealing) with a chemical approach using a sacrificial oxide layer. The layer transfer is achieved through selective chemical etching of the sacrificial oxide, simplifying the overall process complexity while maintaining bonding reliability
3Ease of manufacture
If conventional SOI structures with simple oxide layers are used, then manufacturing is easier, but electrical characteristics are difficult to integrate into devices
Solution Approach 1:
The patent employs a composite dielectric structure consisting of multiple oxide layers with different properties (sacrificial oxide layer and remaining oxide layer). This composite structure enables both ease of manufacture through selective etching and good electrical characteristic integration, as the different oxide layers can be tailored for specific electrical requirements
4Device complexity
If a single oxide layer is used between handle and donor substrates, then the structure is simpler, but layer transfer control and quality are compromised
Solution Approach 1:
The dielectric layer is segmented into multiple oxide layers with distinct functions: a sacrificial oxide layer for selective removal and a remaining oxide layer for maintaining electrical characteristics. This segmentation enables precise control over layer transfer quality while managing structural complexity
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 reduces the cost and complexity of SOI wafer production, improves reliability, and enhances the uniformity and quality of the semiconductor-on-insulator structure by allowing for more robust layer transfer and integration processes.
Implementation Method 1
bonding a handle semiconductor oxide layer in interfacial contact with a front surface of a single crystal semiconductor handle substrate to a donor semiconductor nitride layer in interfacial contact with a front surface of a single crystal semiconductor donor substrate to thereby prepare a bonded structure
Implementation Method 2
The surfaces of the wafers can be additionally chemically activated by a wet treatment, such as an SC1 clean or hydrofluoric acid
Implementation Method 3
the handle semiconductor oxide layer has a wet etch rate ratio greater than 2
Data Source
AI summary
A method is provided for preparing a semiconductor-on-insulator structure comprising a sacrificial layer.