DEPFET Transistor Doping Layout for Short-Channel Signal Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
DEPFET transistors face limitations in achieving high signal-to-noise ratios due to short channel effects when attempting to reduce gate length for improved performance, as this leads to increased avalanche generation and reduced signal amplification.
Innovation Solution
A DEPFET transistor design with a substrate doping enhancement region and a signal charge control region below the gate electrode, where the effective doping dose is higher than in other areas, and a resistance region between the drain connection region and the signal charge control region, reduces the electric field strength and minimizes avalanche generation, allowing for shorter channel lengths without adverse effects on signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the gate length of a DEPFET transistor is made shorter to improve signal-to-noise ratio and detection capability, then the signal amplification and detection precision are improved, but short channel effects occur leading to increased avalanche generation and reduced transistor reliability
Solution Approach 1:
The patent applies local quality by creating a substrate doping enhancement region with higher doping concentration specifically in the channel area beneath the gate electrode. This localized modification of doping concentration allows the channel to maintain stability and reduce avalanche generation in the short channel region, while still benefiting from the shorter gate length for improved signal detection. The non-uniform doping profile addresses the reliability issue locally without compromising the overall short channel design.
2Power
If the gate length is reduced to increase transconductance and signal amplification, then the signal charge detection capability is enhanced, but avalanche generation probability increases due to higher electric field strength in the short channel
Solution Approach 1:
The patent changes the doping concentration parameter in the substrate by introducing a substrate doping enhancement region with higher doping concentration beneath the channel. This parameter change modifies the electric field distribution in the short channel, reducing the peak electric field strength and thereby decreasing avalanche generation probability while maintaining the high transconductance benefits of the short gate length design.
3Measurement precision
If a shorter channel length is used to improve detection precision and reduce capacitance, then the signal-to-noise ratio is improved, but the transistor becomes more susceptible to short channel effects and manufacturing variability
Solution Approach 1:
The patent applies preliminary action by pre-establishing the substrate doping enhancement region during the manufacturing process, before the transistor is put into operation. This preliminary modification of the substrate doping profile compensates for the inherent instability of short channel transistors, making them more robust against manufacturing variability and performance deviations without requiring post-manufacturing adjustments.
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 design enables high signal charge amplification and signal-to-noise ratios while preventing short channel effects, allowing for small channel lengths that enhance detection capabilities without increasing the probability of avalanche generation.
Implementation Method 1
a substrate doping enhancement region of a first conductivity type formed at the first main surface at least under the source connection region and under the channel region
Implementation Method 2
minimizes avalanche generation, allowing for shorter channel lengths without adverse effects on signal-to-noise ratio
Implementation Method 3
a gate electrode above the channel region that is separated from the channel region by a gate insulator
Data Source
AI summary
The invention relates to a DEPFET comprising: a semiconductor substrate (100) of a first conduction type, which has a first main surface (101) and a second main surface (102), which are opposite one another; a source terminal region (1s) of a second conduction type on the first main surface (101); a drain terminal region (1d) of a second conduction type; a channel region (10), which is arranged between the source terminal region (1s) and the drain terminal region (1d); a gate electrode (11), which is separated from the channel region (10) by a gate insulator (6); a rear activation region (104) of a second conduction type, which is formed on the second main surface (102); and a substrate doping increase region (2) of a first conduction type, which is formed at least under the source terminal region (1s) and under the channel region (10), the substrate doping increase region (2) having a signal charge control region (20) of the first conduction type below the gate electrode (11), in which signal charge control region the effective doping dose has a higher value than at other points of the substrate doping increase region (2) below the gate electrode.