High-k Dielectric Layer for Backside Illuminated Image Sensors

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Solution Overview

Problem

The performance of backside illuminated (BSI) semiconductor image sensors is compromised due to shrinking pixel pitch, leading to reduced quantum efficiency and full well capacity, and increased manufacturing costs and time, as existing methods like ion implantation and laser annealing are limited in activating dopants across the high absorption layer.

Innovation Solution

A semiconductor device with a high absorption structure on the substrate, where a dielectric layer with high dielectric constant material is deposited over the high absorption structure, forming a continuous active layer that enhances quantum efficiency and full well capacity, eliminating the need for subsequent ion implantation and laser annealing operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If ion implantation and laser annealing are used to activate dopants in the high absorption layer, then full well capacity is improved, but manufacturing time and cost increase significantly

Engineering Contradiction:

Improvefull well capacityVSAvoidmanufacturing time

Core Design Contradiction:

Quantity of substanceVSLoss of time

Solution Approach 1:

The dopant activation is performed preliminarily during the high-k dielectric material deposition process itself, rather than as a separate subsequent step. The high-k material deposition conditions are specifically controlled to simultaneously achieve both the dielectric layer formation and dopant activation, eliminating the need for separate ion implantation and laser annealing steps.

Inventive Principle:

Principle #10Preliminary action

2Quantity of substance

If ion implantation and laser annealing are used to activate dopants, then full well capacity is improved, but manufacturing cost increases

Engineering Contradiction:

Improvefull well capacityVSAvoidmanufacturing cost

Core Design Contradiction:

Quantity of substanceVSEase of manufacture

Solution Approach 1:

The patent merges the high-k dielectric material deposition process with the dopant activation process into a single integrated step. The deposition conditions (temperature, pressure, material composition) are optimized to simultaneously form the high-k dielectric layer and activate the dopants in the high absorption layer, combining what were previously separate manufacturing operations into one process.

Inventive Principle:

Principle #5Merging (Combining)

3Area of stationary object

If pixel pitch is reduced to shrink sensor size, then device miniaturization is achieved, but quantum efficiency and full well capacity deteriorate

Engineering Contradiction:

Improvesensor sizeVSAvoidquantum efficiency

Core Design Contradiction:

Area of stationary objectVSReliability

Solution Approach 1:

The patent changes the physical and chemical parameters of the high absorption layer by incorporating dopants that are activated during high-k dielectric deposition. This parameter change (dopant activation) enhances the light absorption efficiency and charge carrier generation, thereby improving quantum efficiency and full well capacity even in the reduced pixel pitch configuration.

Inventive Principle:

Principle #35Parameter changes

4Quantity of substance

If conventional dopant activation methods are used, then full well capacity is improved, but substrate damage occurs

Engineering Contradiction:

Improvefull well capacityVSAvoidsubstrate damage

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the mechanical/physical bombardment methods (ion implantation) and high-temperature localized heating (laser annealing) with a chemical vapor deposition-based activation mechanism. The high-k dielectric material deposition process activates dopants through controlled chemical reactions and diffusion during deposition, avoiding the substrate damage associated with ion bombardment and intense laser heating.

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

The solution improves quantum efficiency and full well capacity, reduces manufacturing costs and time, and avoids substrate damage by forming a continuous active layer with high k dielectric material, thereby enhancing the sensitivity and dynamic range of the semiconductor device.

Implementation Method 1

a first high-k dielectric material layer is formed over the high absorption structure

Methodology Applied

Scientific EffectDielectric Permittivity: Dielectric Permittivity

Implementation Method 2

An electrical energy is induced in the photo-diode upon exposure to the light

Methodology Applied

Scientific EffectPhotoelectric Effect: Photoelectric Effect

Data Source

PatentUS10204959B2Semiconductor image sensing device and manufacturing method thereof

Publication Date: 2019.02.12 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A semiconductor device includes a substrate including a front side, a back side opposite to the front side, and a high absorption structure disposed over the back side of the substrate and configured to absorb an electromagnetic radiation in a predetermined wavelength; and a dielectric layer including a high dielectric constant (high k) dielectric material, wherein the dielectric layer is disposed on the high absorption structure.