Cuprous Oxide Transistor Formation Under BEOL Thermal Budgets
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Solution Overview
Problem
Conventional methods for forming cuprous oxide transistors in semiconductor devices face challenges in achieving high quality and consistency at low process temperatures, leading to issues with device performance and reliability due to high thermal budgets and contamination, particularly when integrating peripheral devices like power gates and I/O devices at BEOL levels.
Innovation Solution
A method involving plasma-enhanced oxidation of a crystalline copper layer on an inert dielectric layer, such as aluminum oxide, to form a crystalline cuprous oxide layer at controlled temperatures between 350° C. and 450° C., which is then transferred and bonded to a device substrate for further processing into transistors, utilizing a plasma oxidation process to control oxygen supply and prevent contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional methods are used to form cuprous oxide transistors at low process temperatures, then thermal budget is reduced, but device quality and consistency deteriorate due to high thermal budgets and contamination
Solution Approach 1:
The patent introduces an intermediary plasma oxidation process that occurs at the interface between copper and dielectric layers. This plasma-mediated reaction enables cuprous oxide formation at lower temperatures (350-450°C) while maintaining crystalline quality and preventing contamination, resolving the contradiction between low temperature processing and device quality.
Solution Approach 2:
The patent changes the oxidation parameters by using plasma-enhanced oxidation instead of conventional thermal oxidation. This parameter change allows the oxidation reaction to proceed at lower temperatures while maintaining controlled oxygen supply, resulting in high-quality crystalline cuprous oxide transistors without the thermal budget issues of conventional methods.
2Quantity of substance
If conventional oxidation methods are used, then cuprous oxide can be formed, but contamination occurs and device reliability deteriorates
Solution Approach 1:
The patent uses plasma oxidation in a controlled environment that prevents contamination during cuprous oxide formation. The plasma process occurs in a sealed reactor with controlled gas flow, creating an inert atmosphere that protects the forming transistor from contamination, thereby improving device reliability while maintaining effective cuprous oxide formation.
Solution Approach 2:
The plasma acts as an intermediary that mediates the oxidation reaction in a controlled manner. This plasma-mediated process prevents direct contact between the copper and ambient contaminants, forming cuprous oxide through a controlled plasma reaction that ensures device reliability.
3Temperature
If amorphous silicon transistors are used at FEOL levels, then low process temperature is achieved, but carrier mobility is insufficient for BEOL power gate or I/O devices
Solution Approach 1:
The patent changes the material parameter from amorphous silicon to crystalline cuprous oxide, which inherently provides higher carrier mobility. The plasma oxidation process enables this crystalline material to be formed at low temperatures (350-450°C), resolving the contradiction between low temperature processing and high carrier mobility requirements for BEOL devices.
Solution Approach 2:
The patent utilizes the phase transition from copper metal to crystalline cuprous oxide through plasma oxidation. This phase transition occurs at controlled low temperatures and produces a crystalline semiconductor material with superior carrier mobility compared to amorphous silicon, enabling BEOL device applications.
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
Enables the formation of high-quality crystalline cuprous oxide transistors suitable for BEOL levels with improved carrier mobility, allowing for the fabrication of p-type transistors while adhering to tight thermal budgets, enhancing device performance and reliability.
Implementation Method 1
plasma-enhanced oxidation of a crystalline copper layer on an inert dielectric layer, such as aluminum oxide, to form a crystalline cuprous oxide layer
Implementation Method 2
utilizing a plasma oxidation process to control oxygen supply and prevent contamination
Data Source
AI summary
Structures and methods of forming the same are provided. A structure according to the present disclosure includes an interconnect structure, an aluminum oxide layer over the interconnect structure, and a transistor formed over the aluminum oxide layer. The transistor includes cuprous oxide.