Imaging Device Light Shielding Wall Depth Control

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Solution Overview

Problem

The existing imaging device manufacturing process requires multiple photomask patterns and processing steps to form a light shielding structure for charge accumulation units while maintaining charge transfer paths, leading to increased manufacturing costs.

Innovation Solution

The imaging device employs a light shielding wall with varying depths formed by dry etching using a single photomask pattern, leveraging the microloading effect to control the depth of the trench, allowing the charge accumulation unit to be light-shielded without obstructing the charge transfer path from photodiodes to the charge accumulation unit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If multiple photomask patterns and processing steps are used to form a light shielding structure, then the light shielding performance is improved, but the manufacturing cost increases

Engineering Contradiction:

Improvelight shielding performanceVSAvoidmanufacturing cost

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The light shielding wall is designed with different depths in different regions: a first depth in the region corresponding to the charge transfer path to maintain charge transfer, and a second depth (greater than the first depth) in other regions to provide effective light shielding. This local differentiation allows the structure to simultaneously achieve light shielding performance and charge transfer functionality using a single photomask pattern.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The solution transitions from a two-dimensional planar light shielding structure to a three-dimensional structure with varying depths. By introducing the depth dimension, the light shielding wall can perform multiple functions: shielding light in some areas while preserving charge transfer paths in others, all formed through single dry etching processing.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Object-affected harmful factors

If multiple photomask patterns are used to form the light shielding structure, then the light shielding performance is improved, but the number of processing steps increases

Engineering Contradiction:

Improvelight shielding performanceVSAvoidnumber of processing steps

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The invention combines multiple functions (light shielding and charge transfer path maintenance) into a single integrated light shielding wall structure formed by one photomask pattern. This merging eliminates the need for multiple separate photomask patterns and processing steps, reducing manufacturing complexity while achieving the desired light shielding effect.

Inventive Principle:

Principle #5Merging (Combining)

3Object-affected harmful factors

If a deep light shielding wall is formed to shield the charge accumulation unit, then the light shielding performance is improved, but the charge transfer path may be obstructed

Engineering Contradiction:

Improvelight shielding performanceVSAvoidcharge transfer path

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The light shielding wall implements local quality differentiation with a first depth in the charge transfer path region (allowing charge transfer) and a second depth in other regions (providing light shielding). This ensures that the charge transfer path remains unobstructed while achieving effective light shielding elsewhere.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The light shielding wall is segmented into different depth regions: a first depth portion corresponding to the charge transfer path and a second depth portion for light shielding. This segmentation allows each region to fulfill its specific function without interfering with the other.

Inventive Principle:

Principle #1Segmentation

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 approach reduces the number of photomask patterns and processing steps, thereby lowering manufacturing costs while effectively light-shielding the charge accumulation unit and maintaining the charge transfer path.

Implementation Method 1

the first depth and the second depth of the light shielding wall are formed by dry etching with a photomask pattern

Methodology Applied

Scientific EffectDry etching:

Implementation Method 2

using a processing conversion difference caused by a microloading effect

Methodology Applied

Scientific EffectMicroloading effect:

Data Source

PatentUS11037972B2Imaging device, imaging apparatus, and electronic device

Publication Date: 2021.06.15 SONY SEMICON SOLUTIONS CORP

AI summary

The present disclosure relates to an imaging device, an imaging apparatus, and an electronic device capable of light-shielding a charge accumulation unit at low cost, while maintaining a charge transfer path from a photodiode to a charge accumulation unit. A depth of a trench that forms a trench buried film having a light-shielding characteristic for preventing color mixture of the photodiodes is adjusted according to a contact amount of a reactive gas by adjusting, among the shapes of a photomask pattern, a width of the trench through which the reactive gas flows or the number of intersections of the trenches at a portion in which the trench buried film is formed. As a result, the trench buried films having a plurality of depths can be formed by a single dry etching with one mask pattern, and the manufacturing cost is reduced. Application to an imaging device is possible.