SAW Device Wafer Laser Modified Layer Acoustic Diffusion

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Surface acoustic wave devices experience degraded frequency characteristics due to acoustic waves being reflected from the reverse side of the wafer during operation.

Innovation Solution

A method involving grinding, polishing, and laser beam application to form a modified layer within the wafer that diffuses acoustic waves, preventing reflections and improving frequency characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the wafer is ground and divided into chips, then the surface acoustic wave device chips are produced, but acoustic waves are reflected by the reverse sides of the chips causing degraded frequency characteristics

Engineering Contradiction:

Improvefrequency characteristicsVSAvoidacoustic wave reflection

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent applies laser beams to the reverse side of the wafer to create a modified layer that converts the harmful acoustic wave reflection into beneficial acoustic wave diffusion. The laser-modified layer acts as an acoustic diffusion structure that prevents reflections from reaching the output IDT, thereby improving frequency characteristics while maintaining the standard wafer grinding and chip division process

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent changes the physical parameters of the wafer reverse side by applying laser energy to modify the material structure. The laser beam parameters (wavelength, power, scanning speed) are controlled to create a modified layer with specific acoustic properties that diffuse acoustic waves rather than reflect them, thus improving frequency characteristics without affecting the device structure

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If a modified layer is formed by laser beam application, then acoustic wave diffusion is achieved, but additional manufacturing steps are required

Engineering Contradiction:

Improvefrequency characteristicsVSAvoidmanufacturing process

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces potential mechanical or chemical methods for creating acoustic diffusion structures with a laser-based process. The laser beam application provides a non-contact, precise, and controllable method to modify the wafer reverse side, achieving acoustic wave diffusion without adding complex mechanical structures or chemical treatment steps to the manufacturing process

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 method effectively prevents acoustic wave reflections, resulting in surface acoustic wave device chips with enhanced frequency characteristics.

Implementation Method 1

a laser beam applying step of applying a laser beam having a wavelength with which the wafer is transmittable to the reverse side of the wafer such that the laser beam is focused at a position within the wafer

Methodology Applied

Scientific EffectLaser heating: Laser

Implementation Method 2

to modify an inside of the wafer at the area in which the surface acoustic wave device is formed, thereby forming a modified layer

Methodology Applied

Scientific EffectOptical absorption and thermal conversion: Absorption (EM radiation)

Implementation Method 3

forming a modified layer for diffusing an acoustic wave... an acoustic wave is prevented from being reflected by the reverse sides of the surface acoustic wave device chips

Methodology Applied

Scientific EffectAcoustic wave diffusion: Diffusion

Implementation Method 4

a grinding step of grinding a reverse side of a wafer with a surface acoustic wave device formed in each area

Methodology Applied

Scientific EffectAbrasion: Abrasion

Implementation Method 5

a polishing step of polishing the reverse side of the wafer

Methodology Applied

Scientific EffectMechanical polishing: Abrasion

Data Source

PatentUS10826456B2Method of manufacturing surface acoustic wave device chips

Publication Date: 2020.11.03 DISCO CORP

AI summary

A method of manufacturing surface acoustic wave device chips includes grinding a reverse side of a wafer with a surface acoustic wave device formed in each area demarcated by a plurality of crossing projected dicing lines on a face side of the wafer; before or after grinding, applying a laser beam to the reverse side of the wafer such that the laser beam is focused at a position within the wafer, the position being closer to the face side of the wafer than a position corresponding to a reverse side of each of the surface acoustic wave device chips to be produced from the wafer, thereby forming a modified layer for diffusing an acoustic wave; and after grinding and applying the laser beam, dividing the wafer along the projected dicing lines into a plurality of the surface acoustic wave device chips.