Semiconductor Charge-Attracting Layer for X-Ray Sensor Stability
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Solution Overview
Problem
X-ray sensors on SOI substrates face characteristic changes in transistors due to positive charge accumulation in insulating regions, leading to unintended current generation and operational fluctuations, which existing technologies do not adequately address.
Innovation Solution
A semiconductor device with a charge-attracting layer configured to attract electrical charges generated in the insulating layer by applying a predetermined voltage, using a buried polysilicon layer and a buried well to reduce positive charge accumulation near the transistor, thereby suppressing characteristic changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a buried oxide film is used to isolate the sensor and circuit layers, then electrical isolation and device performance are improved, but positive charge accumulation in the oxide film causes transistor characteristic changes and leak current
Solution Approach 1:
A polysilicon charge-attracting layer is introduced as an intermediary between the buried oxide film and the transistor. This layer mediates the interaction by attracting and trapping positive charges that would otherwise accumulate in the oxide film and affect transistor characteristics, thus protecting the transistor while maintaining the electrical isolation function of the oxide film.
Solution Approach 2:
The invention converts the harmful effect of charge accumulation by providing a dedicated charge-attracting layer that intentionally traps positive charges. This layer acts as a sacrificial element that absorbs the harmful charges, preventing them from reaching the transistor and causing characteristic changes or leak current.
2Measurement precision
If the total amount of X-ray radiation increases, then sensor detection capability is improved, but positive charge accumulation in the oxide film increases causing transistor characteristic fluctuations
Solution Approach 1:
The polysilicon charge-attracting layer serves as a mediator that decouples the relationship between X-ray radiation and transistor characteristics. It allows the sensor to detect X-rays effectively while intercepting the harmful charge accumulation that would otherwise directly affect transistor stability during radiation exposure.
Solution Approach 2:
The charge-attracting layer provides beforehand cushioning by being positioned to preemptively capture positive charges generated during X-ray radiation. This protective layer is in place before radiation occurs, cushioning the transistor against the destabilizing effects of charge accumulation even as radiation dose increases.
3Ease of operation
If positive charges are trapped in the field oxide film or buried oxide film, then X-ray sensor operation is maintained, but threshold voltage or current amount of the transistor changes
Solution Approach 1:
The polysilicon charge-attracting layer acts as an intermediary that selectively traps positive charges before they can reach the transistor's field oxide film or buried oxide film. This maintains sensor operation while preventing the charge-induced threshold voltage shifts that would compromise manufacturing precision and device performance.
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 semiconductor device effectively reduces the accumulation of positive charges in the insulating layer, minimizing their impact on transistor operation and maintaining accurate sensor functionality.
Implementation Method 1
a charge-attracting layer configured to attract electrical charges generated in the insulating layer when a predetermined voltage is supplied to the charge-attracting layer
Data Source
AI summary
A semiconductor device includes a first semiconductor layer of a first conductivity type having a first surface on one side thereof and a second surface on an opposite side thereof, and having an element therein, a second semiconductor layer of a second conductivity type having a circuit element formed therein, the second semiconductor layer being formed at the one side of the first surface of the first semiconductor layer, an insulating layer disposed on the first surface of the first semiconductor layer, and a charge-attracting layer configured to attract electrical charges generated in the insulating layer when a predetermined voltage is supplied to the charge-attracting layer.