Light-Sensing Transistor With Direct Metal-Semiconductor Junction

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Solution Overview

Problem

The existing thin film transistor (TFT) manufacturing process for light sensing devices faces challenges in achieving high light sensitivity due to incompatibility with low temperature poly-silicon (LTPS) processes, particularly because the doping of n-plus material is not compatible with these processes.

Innovation Solution

A light sensing transistor design where the metal layer is in direct contact with the semiconductor layer without an intermediating n-plus layer, allowing for better compatibility with various manufacturing processes and utilizing chemical vapor deposition methods to deposit the semiconductor layer, which enhances light sensitivity through light-induced barrier lowering (LIBL) at the junction interface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If an intermediating n-plus layer is used between metal layer and semiconductor layer, then manufacturing process compatibility is improved, but light sensitivity deteriorates

Engineering Contradiction:

Improvemanufacturing process compatibilityVSAvoidlight sensitivity

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent removes the intermediating n-plus layer from the structure, allowing direct contact between the metal layer and semiconductor layer. This extraction of the problematic layer resolves the contradiction by eliminating the barrier to light-induced carrier generation while maintaining manufacturing feasibility through direct deposition processes.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent employs a composite structure where the metal layer and semiconductor layer are directly interfaced, creating a heterostructure that leverages the unique properties of both materials. This direct interface enables efficient light-induced barrier lowering (LIBL) effect while maintaining process compatibility through careful material selection and deposition parameter optimization.

Inventive Principle:

Principle #40Composite materials

2Measurement precision

If direct contact between metal layer and semiconductor layer is implemented, then light sensitivity is improved, but manufacturing process compatibility worsens

Engineering Contradiction:

Improvelight sensitivityVSAvoidmanufacturing process compatibility

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent optimizes critical parameters including deposition temperatures, layer thicknesses, and material compositions to enable direct metal-semiconductor contact. By carefully controlling these parameters, the invention achieves the desired direct interface for enhanced light sensitivity while maintaining compatibility with existing manufacturing processes through parameter adjustment rather than process redesign.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If n-plus material doping is used, then device performance is improved, but compatibility with low temperature poly-silicon process deteriorates

Engineering Contradiction:

Improvedevice performanceVSAvoidprocess compatibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent replaces the chemical doping process (n-plus material implantation) with a physical deposition approach where the metal layer is directly deposited onto the semiconductor layer. This substitution eliminates the need for high-temperature doping processes, thereby maintaining compatibility with low temperature poly-silicon manufacturing while achieving enhanced device performance through the direct metal-semiconductor interface and LIBL effect.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 improves light sensitivity and compatibility with different manufacturing processes, enabling higher linearity and sensitivity to incident light, while also allowing for effective shielding of noise from the backside light, thus enhancing the signal-to-noise ratio.

Implementation Method 1

utilizing chemical vapor deposition methods to deposit the semiconductor layer, which enhances light sensitivity through light-induced barrier lowering (LIBL) at the junction interface

Methodology Applied

Scientific EffectLight-induced barrier lowering (LIBL): Photoelectric Effect

Implementation Method 2

utilizing chemical vapor deposition methods to deposit the semiconductor layer

Methodology Applied

Scientific EffectChemical vapor deposition: Chemical Vapour Deposition

Data Source

PatentUS20240290903A1Light sensing transistor

Publication Date: 2024.08.29 NOVATEK MICROELECTRONICS CORP

AI summary

A light sensing transistor is provided. The light sensing transistor includes a substrate, a metal layer, and a semiconductor layer. The metal layer and the semiconductor layer are disposed on the substrate. The metal layer has a first metal structure and a second metal structure. The first metal structure and the second metal structure are in direct contact with the semiconductor layer.