Laser Wafer Cutting via Beam Splitting for Groove Quality

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Solution Overview

Problem

The existing laser cutting method for semiconductor wafers requires multiple passes and complex setups to achieve high-quality grooves, leading to reduced productivity and potential damage to the brittle top layer.

Innovation Solution

A single high-power laser beam is divided into multiple beams using a controllable beam deflector, allowing for simultaneous performance of multiple cutting actions in a single pass, such as cutting both trenches and the fissure, to enhance productivity and precision.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a traditional blade dicing method is used to cut the wafer, then the cutting process is simple and fast, but the brittle top layer of the dicing streets suffers severe damage

Engineering Contradiction:

Improvecutting speedVSAvoiddamage to top layer

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the mechanical blade dicing system with a laser-based system. The laser beam removes material through ablation rather than mechanical contact, eliminating the severe damage caused by blade pressure and friction on the brittle top layer while maintaining cutting efficiency

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Object-affected harmful factors

If a hybrid dicing process with two-step laser cutting is used to remove the top layer and cut bulk silicon, then the top layer damage is minimized, but the device complexity and processing time increase

Engineering Contradiction:

Improvedamage to top layerVSAvoidcomplexity of laser setup

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent segments a single high-power laser beam into multiple lower-power beams using a beam splitter. These segmented beams can be independently directed to perform different cutting functions (removing top layer and cutting bulk silicon) simultaneously, reducing device complexity while maintaining the benefits of selective material removal

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent makes a single laser source perform multiple functions by combining it with a beam splitter. The same laser beam is divided to simultaneously execute top layer removal and bulk silicon cutting, eliminating the need for separate laser systems and reducing overall device complexity

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Manufacturing precision

If a hybrid dicing process with two-step laser cutting is used to achieve high-quality grooves, then the groove quality is improved, but the productivity decreases due to multiple passes

Engineering Contradiction:

Improvegroove qualityVSAvoidcutting throughput

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent merges the two separate cutting steps (top layer removal and bulk silicon cutting) into a single simultaneous operation. By splitting the laser beam and directing different segments to different cutting tasks at the same time, the system maintains high groove quality while doubling the cutting throughput

Inventive Principle:

Principle #5Merging (Combining)

4Area of stationary object

If the dicing streets are made very narrow to maximize wafer surface area usage, then the wafer utilization is improved, but the precision requirements for dicing become extremely severe

Engineering Contradiction:

Improvewafer surface area utilizationVSAvoiddicing precision

Core Design Contradiction:

Area of stationary objectVSManufacturing precision

Solution Approach 1:

The patent replaces mechanical blade dicing with laser ablation, which offers superior precision control. The laser can accurately define narrow dicing streets with precise width and depth control, enabling maximum wafer utilization without compromising on the extremely tight precision requirements

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 significantly improves productivity by completing the cutting process in fewer passes while maintaining high-quality results and minimizing damage to the wafer's top layer, achieving efficient use of the wafer surface.

Implementation Method 1

a first step where radiation, typically a high power laser beam, is used to remove the top layer of the dicing streets

Methodology Applied

Scientific EffectLaser ablation: Laser Ablation

Implementation Method 2

Laser power and beam speed are controlled such that the top region of the wafer 1 is removed (ablated)

Methodology Applied

Scientific EffectAblation: Ablation

Data Source

PatentUS9786562B2Method and device for cutting wafers

Publication Date: 2017.10.10 ASMPT SINGAPORE PTE LTD

AI summary

A method is described of radiatively cutting a wafer, the method comprising the steps of low power cutting of two trenches followed by high power cutting of a fissure. A single pulsed radiation beam is split into a first pulsed radiation beam for cutting at least one of the trenches and a second pulsed radiation beam for cutting the fissure. When cutting a fissure on the wafer in a cutting direction along a cutting street, the first and second radiation beams are directed simultaneously with the first radiation beam leading and the second radiation beam trailing. For cutting a fissure in the opposite cutting direction, a third pulsed radiation beam for trenching is split from said single pulsed radiation beam.