Back-Biased MOSFET Memory Cell for Higher Drain Current
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Solution Overview
Problem
Conventional MOSFETs do not effectively utilize the inherent bipolar junction transistor (BJT) formed during manufacturing, leading to underperformance in on-state drain current, and require higher operating voltages for memory cells.
Innovation Solution
A semiconductor device structure and method that leverages the inherent BJT by adjusting voltage applied to the buried layer to enhance on-state drain current while maintaining unchanged off-state drain current, allowing the device to function as either a MOSFET or a memory cell with multiple stable states at reduced operating voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional MOSFET manufacturing process is used, then the inherent BJT is formed but not utilized, but the on-state drain current is insufficient
Solution Approach 1:
The patent utilizes the inherently formed BJT structure during standard MOSFET manufacturing without requiring additional fabrication steps. The BJT is activated through specific biasing conditions applied during operation, allowing the device to self-enhance its drain current using structures already present from the manufacturing process
Solution Approach 2:
The patent changes the electrical parameters (bias voltages) applied to the MOSFET to activate the inherent BJT. By applying specific voltage conditions to the gate and drain, the BJT is turned on to provide current amplification, thereby increasing the on-state drain current without modifying the physical structure or manufacturing process
2Power
If the inherent BJT is activated to increase on-state current, then drain current is improved, but off-state drain current may increase
Solution Approach 1:
The patent dynamically controls the BJT activation state through time-varying bias conditions. The BJT is activated only during specific operational phases (when high current is needed) and deactivated during other phases, allowing the system to adapt between high on-state current and low off-state current requirements
Solution Approach 2:
The patent uses dynamic parameter changes in the form of time-varying voltage biases to control BJT activation. By adjusting the gate and drain voltages according to operational requirements, the system can turn the BJT on during read operations to boost current and turn it off during write operations to maintain low leakage
3Use of energy by moving object
If conventional memory cell operation is used, then the device functions as MOSFET, but operating voltage is high
Solution Approach 1:
The patent introduces the inherent BJT as an intermediary element that facilitates lower voltage operation. The BJT acts as a current amplifier that enables memory cell operations at reduced voltages by providing the necessary current gain that would otherwise require higher voltage swings
Solution Approach 2:
The patent makes the semiconductor device multi-functional by enabling it to operate in different modes (MOSFET mode and BJT-enhanced mode) depending on the applied bias conditions. This universality allows the same device structure to function as both a conventional MOSFET and a low-voltage memory cell
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
The solution significantly increases on-state drain current and enables reduced operating voltage for memory cells, improving performance and efficiency by effectively utilizing the inherent BJT and adjusting voltage levels.
Implementation Method 1
the on-state drain current is increased due to the turned-on BJT when the MOSFET is turned on but the off-state drain current is unchanged due to the turned-off BJT when the MOSFET is turned off
Data Source
AI summary
A semiconductor metal-oxide-semiconductor field effect transistor (MOSFET) transistor with increased on-state current obtained through intrinsic bipolar junction transistor (BJT) of MOSFET has been described. Methods of operating the MOS transistor are provided.