Laser Singulation Apparatus Displacing Energy Peak to Suppress Scattered Light
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Solution Overview
Problem
In semiconductor manufacturing, the reflection or refraction of laser light during chip singulation can damage integrated circuits due to scattered light, and existing methods to mitigate this either reduce productivity or compromise the quality of chip singulation.
Innovation Solution
A semiconductor manufacturing apparatus that uses a light modulator to displace the peak energy density distribution of the laser light from the optical axis, allowing the laser to focus on a specific position without passing through modified regions, thereby minimizing scattered light and ensuring high-quality chip singulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If laser output is reduced to suppress scattered light, then damage to semiconductor integrated circuit is suppressed, but modified regions become small requiring increased number of laser passes resulting in lower productivity
Solution Approach 1:
The patent applies local quality by creating a modified layer with specific properties at the focal point where laser energy is concentrated. The modified layer has different physical properties (cleavage planes) compared to the surrounding substrate, allowing selective cleavage. This localized modification enables effective singulation without requiring high laser output throughout the entire processing area, thus reducing scattered light while maintaining processing efficiency.
Solution Approach 2:
The patent utilizes the depth dimension by focusing laser energy at a specific focal point within the semiconductor substrate rather than on the surface. This three-dimensional focusing creates the modified layer at a controlled depth, allowing the laser to pass through the substrate without excessive interaction with surface features that would generate scattered light, thereby maintaining productivity while suppressing scattered light damage.
2Object-affected harmful factors
If laser irradiation pitch is widened to suppress scattered light, then laser is less likely to enter already formed cleaved surface, but cleaved surface stability deteriorates making high quality singulation difficult
Solution Approach 1:
The patent applies preliminary action by creating the modified layer with cleavage planes before the actual cleavage process. This pre-formed modified layer provides a stable guide for subsequent cleavage, ensuring that the cleaved surface follows the intended path accurately. The modified layer acts as a predetermined track that maintains cleaved surface stability even when laser irradiation pitch is adjusted to suppress scattered light.
3Productivity
If high laser output is used to maintain processing speed, then productivity is maintained, but scattered light increases causing damage to semiconductor integrated circuit
Solution Approach 1:
The patent extracts the harmful scattered light generation mechanism by separating the laser focusing function from the cleavage function. By concentrating laser energy precisely at the focal point to create the modified layer and then using mechanical or chemical processes for the actual cleavage, the system maintains high processing speed without the need for continuous high-power laser irradiation that would generate scattered light and damage the integrated circuit.
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 effectively suppresses scattered light, allowing for efficient and high-quality singulation of semiconductor chips while maintaining productivity by adjusting the peak energy density distribution in real-time with the movement of the objective lens.
Implementation Method 1
a method of focusing laser on the semiconductor substrate to generate a modified layer
Implementation Method 2
focusing laser on the semiconductor substrate to generate a modified layer
Implementation Method 3
The modified layer in the semiconductor substrate is cleaved to some extent by internal stress
Implementation Method 4
the laser is sometimes reflected or refracted on the cleaved surface
Implementation Method 5
the laser is sometimes reflected or refracted on the cleaved surface
Data Source
AI summary
A semiconductor manufacturing apparatus according to an embodiment irradiates a semiconductor substrate with laser to form modified regions along an intended cut line in the semiconductor substrate. A light source emits the laser. An optical system comprises an objective lens configured to focus the laser in the semiconductor substrate. A light modulator is capable of modulating an energy density distribution of the laser. A controller controls the light modulator to displace a peak position of the energy density distribution of the laser from an optical axis of the objective lens in a relative movement direction of the optical system with respect to the semiconductor substrate.