Back-End TFT Voltage Regulator for High-Frequency Scaling
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Solution Overview
Problem
Traditional voltage regulator circuits using front-end transistors consume substrate area, operate at low frequencies due to low on/off ratio and high parasitic capacitance, and are not scalable, requiring multiple stages which limits efficiency.
Innovation Solution
The use of thin-film transistors (TFTs) in voltage regulator circuits, which are formed through back-end processing, allowing for higher mobility and thicker gate oxide layers, enabling higher frequency operation and reduced size and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If traditional front-end transistors (MOS or BJT) are used in voltage regulator circuits, then the circuit can provide voltage regulation function, but the substrate area is consumed and the device size cannot be scaled down
Solution Approach 1:
The patent moves the transistor from the front-end substrate plane to the back-end vertical dimension by forming TFTs above the substrate using stacked structures. This dimensional transition allows the transistor to operate outside the traditional substrate area constraints, enabling area-efficient integration and scalability to smaller sizes while maintaining voltage regulation functionality.
Solution Approach 2:
The patent implements a stacked configuration where the TFT is formed above the substrate, with the gate electrode, gate dielectric layer, and channel layer arranged in vertical tiers. This nesting approach allows multiple functional layers to occupy the same footprint area, reducing the overall substrate area consumption and enabling better scaling.
2Speed
If traditional front-end transistors are used, then voltage regulation can be achieved, but the operating frequency is limited due to low on/off ratio and large parasitic capacitance
Solution Approach 1:
The patent changes the material parameters of the transistor by using amorphous silicon or other semiconductor materials with different electrical characteristics than traditional crystalline silicon. This parameter change results in reduced parasitic capacitance and improved on/off ratio, enabling higher operating frequencies while maintaining reliable voltage regulation.
Solution Approach 2:
The patent employs amorphous silicon channel layers that can be formed using low-temperature processes, creating a transistor structure with inherently lower parasitic capacitance. This approach trades the complexity of traditional high-performance transistor fabrication for a simpler structure that achieves superior high-frequency performance through reduced capacitive effects.
3Loss of energy
If multiple stage voltage regulators are used to overcome limitations, then voltage regulation can be maintained, but the circuit efficiency is reduced
Solution Approach 1:
The TFT-based voltage regulator structure provides multiple benefits simultaneously: it enables area reduction, improves scalability, enhances operating frequency, and maintains efficient single-stage operation. This multi-functional transistor design eliminates the need for cascaded stages while achieving all desired performance characteristics in a unified structure.
Data Source
AI summary
Described herein are apparatuses, systems, and methods associated with a voltage regulator circuit that includes one or more thin-film transistors (TFTs). The TFTs may be formed in the back-end of an integrated circuit. Additionally, the TFTs may include one or more unique features, such as a channel layer treated with a gas or plasma, and/or a gate oxide layer that is thicker than in prior TFTs. The one or more TFTs of the voltage regulator circuit may improve the operation of the voltage regulator circuit and free up front-end substrate area for other devices. Other embodiments may be described and claimed.