Split-Beam Laser Wafer Grooving to Prevent Low-k Layer Peeling
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Solution Overview
Problem
Laser processing methods for semiconductor wafers with stacked Low-k films face challenges in preventing peeling off of functional layers during division, leading to potential damage to chips.
Innovation Solution
A laser processing apparatus with a holding unit, a laser beam irradiation unit that focuses pulsed laser beams, and a movement unit, which includes optical splitting and condensing components to create multiple laser beams that scan and focus in specific directions, forming grooves that separate the functional layer without peeling, using a configuration that includes a first and second beam condenser setup with additional splitting units to manage beam paths and power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a scanning optical system that executes scanning with a laser beam is disposed between a laser oscillator and a beam condenser to efficiently form a dividing groove with sufficient width, then productivity is improved, but the stacked functional layer may be peeled off and reach a device to damage a chip
Solution Approach 1:
The patent divides the laser beam into multiple beams (first laser beam and second laser beam) that travel through separate optical paths with different condensers (first beam condenser and second beam condenser). This segmentation allows independent control of each beam's focus and parameters, enabling the formation of dividing grooves while preventing functional layer peeling by optimizing each beam's contribution to the overall processing.
2Reliability
If multiple laser beams are created with separate optical paths and condensers to prevent functional layer peeling, then functional layer integrity is improved, but device complexity increases
Solution Approach 1:
The patent employs a second splitting unit that can split either the first laser beam or the second laser beam into at least two laser beams, creating a multi-functional optical system. This universal splitting capability allows the same optical components to serve multiple purposes: creating dividing grooves, preventing functional layer peeling, and enabling flexible beam configuration without requiring entirely separate systems for each function.
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 apparatus efficiently divides semiconductor wafers while minimizing peeling of the functional layer, reducing the risk of chip damage and allowing for precise control over the processing area, thereby enhancing productivity and reducing facility occupation.
Implementation Method 1
a laser beam irradiation unit that focuses a pulsed laser beam and irradiates the workpiece held on the holding unit with the laser beam to execute processing
Implementation Method 2
a first splitting unit that causes the laser beam emitted from the laser oscillator to branch into a first optical path and a second optical path
Implementation Method 3
a first beam condenser that focuses the laser beam having been introduced to the first optical path, a second beam condenser that focuses the laser beam having been introduced to the second optical path
Implementation Method 4
an acousto-optic element that is disposed on the first optical path between the laser oscillator and the polygon scanner and that executes scanning with the laser beam in the width direction of a planned dividing line set in the workpiece
Data Source
AI summary
A laser beam irradiation unit of a laser processing apparatus includes a first splitting unit that causes a laser beam emitted from a laser oscillator to branch into a first optical path and a second optical path, a first beam condenser that focuses the laser beam having been introduced to the first optical path, and a second beam condenser that focuses the laser beam having been introduced to the second optical path. The laser beam irradiation unit further includes a second splitting unit on the first optical path between the first splitting unit and the first beam condenser that splits the laser beam into at least two laser beams, and a laser beam scanning unit on the second optical path between the first splitting unit and the second beam condenser that executes scanning with the laser beam and introduces the laser beam to the second beam condenser.