Curved Sensor Substrate for Solid State Imaging Device

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Solution Overview

Problem

In solid state imaging devices, variations in the gap between the sensor substrate and the microlens array lead to shifts in the light axis, causing image quality degradation due to light axis misalignment and field curvature aberration, which results in color mixture and reduced accuracy of image matching with parallaxes.

Innovation Solution

A solid state imaging device is designed with a sensor substrate curved to recess its upper face, allowing for precise alignment with a microlens array substrate, using connection posts that absorb visible light to prevent color mixture and enhance image quality by maintaining parallelism between the substrates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the microlens array is arranged apart from the sensor substrate to enable distance detection, then depth measurement capability is improved, but variations in the gap cause light axis shifts and image quality degradation

Engineering Contradiction:

Improvedistance detection capabilityVSAvoidgap variation control

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The sensor substrate is curved to form a recessed portion that accommodates the microlens array, transforming the flat substrate into a curved surface. This curvature compensates for gap variations and maintains proper optical alignment between the microlens array and sensor substrate across the entire imaging area, resolving the light axis shift problem while preserving distance detection capability

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The sensor substrate is selectively curved only in the region where the microlens array is arranged, forming a localized recessed portion. This local curvature modification allows precise control of the gap between the microlens array and sensor substrate without affecting the entire substrate, thereby maintaining manufacturing precision while enabling distance detection

Inventive Principle:

Principle #3Local quality

2Manufacturing precision

If the microlens array is formed directly on the sensor substrate to maintain parallelism, then alignment precision is improved, but distance detection capability is lost

Engineering Contradiction:

Improveparallelism between pixels and microlensesVSAvoiddistance detection capability

Core Design Contradiction:

Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

By curving the sensor substrate to form a recessed portion, the invention maintains the close proximity and alignment between the microlens array and sensor substrate (preserving manufacturing precision) while creating the necessary spatial separation for distance detection functionality

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The invention transitions from a two-dimensional flat substrate arrangement to a three-dimensional curved substrate structure. This dimensional change allows the microlens array to be positioned at a specific distance from the sensor substrate while maintaining alignment, enabling both high precision imaging and distance detection capabilities

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Use of energy by moving object

If connection posts are made transparent to allow light transmission, then optical efficiency is improved, but color mixture occurs due to light axis shifts

Engineering Contradiction:

Improvelight transmission efficiencyVSAvoidcolor mixture

Core Design Contradiction:

Use of energy by moving objectVSObject-generated harmful factors

Solution Approach 1:

The curved sensor substrate with recessed portion maintains proper optical alignment between connection posts and microlenses, preventing light axis shifts that cause color mixture. This allows connection posts to remain transparent for optimal light transmission while avoiding the harmful effect of chromatic aberration

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The recessed portion of the curved sensor substrate acts as an intermediary structure that positions the microlens array at the optimal distance and alignment relative to the connection posts. This intermediate curvature ensures that light passing through transparent connection posts remains properly aligned, preventing color mixture while maintaining optical efficiency

Inventive Principle:

Principle #24Intermediary (Mediator)

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 configuration ensures high image quality by preventing light axis shifts and field curvature aberration, thereby improving the accuracy of image matching and reducing optical crosstalk, while maintaining a high density of pixels and microlenses without the need for additional optical elements.

Implementation Method 1

connection posts that absorb visible light to prevent color mixture

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Data Source

PatentUS8742527B2Solid state imaging device, solid state imaging element, portable information terminal device and method for manufacturing the solid state imaging element

Publication Date: 2014.06.03 KK TOSHIBA

AI summary

According to one embodiment, a solid state imaging device includes a sensor substrate curved such that an upper face having a plurality of pixels formed is recessed and an imaging lens provided on the upper face side.