Ultrasonic Biometric Sensor Single-Substrate Fabrication

Solution Overview

Problem

Conventional ultrasonic fingerprint sensors rely on costly wafer bonding technology, which limits yield and increases manufacturing costs, and capacitive sensors struggle with penetration through glass panels and are vulnerable to counterfeiting due to poor 3D imaging and security.

Innovation Solution

Fabricating an ultrasonic biometric sensor with a control circuit and ultrasonic transducer array on a single substrate using anisotropic etching to form cavities, eliminating the need for wafer bonding and enhancing productivity and cost-effectiveness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If wafer bonding technology is used to interconnect ultrasonic transducer chip and CMOS detection chip, then electrical connection is achieved, but manufacturing cost increases and yield decreases

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidmanufacturing yield

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent merges the ultrasonic transducer array and control circuit onto a single substrate, eliminating the need for wafer bonding between separate chips. This integration approach maintains electrical connection reliability while significantly improving manufacturing yield and reducing production complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent extracts the electrical interconnection step (wafer bonding) from the manufacturing process by designing the system to operate with both components on one substrate. This removes the problematic bonding step that caused low yield and high cost, while preserving the essential electrical connection function through on-substrate routing.

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If wafer bonding technology is used to interconnect ultrasonic transducer chip and CMOS detection chip, then electrical connection is achieved, but fabrication cost increases

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidfabrication cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent merges the ultrasonic transducer array and control circuit onto a single substrate, eliminating the need for wafer bonding between separate chips. This integration approach maintains electrical connection reliability while significantly improving manufacturing yield and reducing production complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent extracts the electrical interconnection step (wafer bonding) from the manufacturing process by designing the system to operate with both components on one substrate. This removes the problematic bonding step that caused low yield and high cost, while preserving the essential electrical connection function through on-substrate routing.

Inventive Principle:

Principle #2Taking out (Extraction)

3Device complexity

If capacitive fingerprint sensor is used, then simple structure is achieved, but penetration capability through glass panel deteriorates

Engineering Contradiction:

Improvesensor structure complexityVSAvoidpenetration capability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent replaces the capacitive sensing mechanism with ultrasonic wave-based sensing. Ultrasonic waves can penetrate glass panels and various materials effectively, providing reliable penetration capability while maintaining reasonable device complexity through integrated circuit design.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Device complexity

If capacitive fingerprint sensor is used, then simple structure is achieved, but anti-counterfeit capability deteriorates

Engineering Contradiction:

Improvesensor structure complexityVSAvoidanti-counterfeit capability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent replaces the capacitive sensing mechanism with ultrasonic wave-based sensing. Ultrasonic waves can penetrate glass panels and various materials effectively, providing reliable penetration capability while maintaining reasonable device complexity through integrated circuit design.

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 approach reduces fabrication costs and increases yield while providing superior penetration and anti-counterfeiting capabilities through improved 3D imaging and security.

Implementation Method 1

an ultrasonic transducer array arranged on the first region and comprising a plurality of arrayed piezoelectric elements

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

While propagating in media of different densities and encountering different acoustic impedances, ultrasonic waves will generate different reflection waves intensity

Methodology Applied

Scientific EffectAcoustic impedance: Acoustics

Data Source

PatentUS10303915B2Ultrasonic biometric sensor

Publication Date: 2019.05.28 ORIENTAL SYST TECH

AI summary

An ultrasonic biometric sensor comprises a detection chip. The detection chip includes a substrate, an ultrasonic transducer array and a control circuit. The ultrasonic transducer array is arranged on the substrate, including a plurality of arrayed piezoelectric elements. Each piezoelectric element is disposed on a floating membrane. The floating membrane is suspended in the opening side of a cavity by at least one support arm extending transversely. The control circuit is also arranged on the substrate and electrically connected with each piezoelectric element through the support arm to control the ultrasonic transducer array to generate an ultrasonic signal and read the reflected ultrasonic signal received by the ultrasonic transducer array. The ultrasonic biometric sensor is easy to fabricate and has a high yield.