Laser Dicing Wafer Edge Position Control
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Solution Overview
Problem
Conventional dicing methods using diamond abrasive blades cause chipping on the surface and rear of semiconductor wafers, leading to performance degradation, and laser processing methods face challenges in accurately controlling the condensing point of laser light near the wafer's edge, resulting in incomplete cutting.
Innovation Solution
A laser dicing apparatus with separate position detecting devices for surface alignment and real-time control, allowing for precise adjustment of the laser's condensing point inside the wafer, even near the edge, by using a second position detecting device to pre-detect the surface position and a control section to switch control based on data from both devices during scanning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a single position detecting device is used for real-time surface detection during laser scanning, then the control response is fast, but the condensing point cannot be accurately controlled at the periphery of the wafer due to delay in position data acquisition
Solution Approach 1:
The system performs preliminary detection of the wafer surface position at the periphery using the second position detecting device before laser scanning begins. This pre-acquired position data is stored and used to control the condensing point position during the scanning process, eliminating the delay that would occur if real-time detection were used at the periphery.
Solution Approach 2:
The position detection function is segmented into two separate devices: the first position detecting device for real-time detection during scanning, and the second position detecting device for preliminary detection at the periphery. This segmentation allows each device to specialize in its optimal function, with the second device providing accurate periphery position data in advance.
2Productivity
If laser light is scanned from the outside of the edge of the wafer toward the inside, then the processing covers the entire wafer, but the condensing point cannot be adjusted to the inside of the wafer at the periphery resulting in incomplete cutting
Solution Approach 1:
The system acquires position data at the periphery of the wafer in advance using the second position detecting device before the laser scanning begins. This preliminary position information is then used to accurately control the condensing point position during the scanning process, ensuring that the modified region is formed at the correct depth even at the periphery where real-time detection would be too slow.
3Productivity
If conventional dicing blade is used to cut the wafer, then the cutting process is simple and fast, but chipping is generated on the front surface and rear surface of the wafer degrading chip performance
Solution Approach 1:
The system replaces the mechanical dicing blade with a laser-based processing method. The laser light forms a modified region inside the wafer through multi-photon absorption, and the wafer is divided by utilizing this modified region as a reference point. This substitution eliminates the mechanical contact that causes chipping while maintaining efficient processing.
Solution Approach 2:
The system changes the processing parameter from mechanical force to optical energy. By controlling the laser light parameters (intensity, duration, focal position) to create a modified region at a specific depth inside the wafer, the cutting process avoids surface chipping while achieving complete separation of chips.
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
Enables the formation of modified regions by multi-photon absorption at predetermined positions inside the wafer, reducing chipping and improving the precision and efficiency of the dicing process by allowing accurate control of the laser's position at the wafer's periphery.
Implementation Method 1
laser light with a condensing point arranged inside the wafer is made incident so as to form a modified region by multi-photon absorption inside the wafer
Data Source
AI summary
There is provided a laser dicing apparatus comprising: a first position detecting device detecting a position of the surface of a wafer at an incident point of laser light; second position detecting device detecting in advance a position of the surface of the wafer; and a control section controlling the position in the thickness direction of a condensing point inside the wafer, wherein the control section, when scanning the laser light from the outside of a periphery of the wafer to the inside of the periphery of the wafer, performs control based on data obtained with the second position detecting device detecting the position of the condensing point at the periphery of the wafer, and after scanning a predetermined distance, switches to perform control based on data obtained by the first position detecting device. Thereby, when the laser light is made incident through the surface of the wafer and scanned, the position control of the condensing point of the laser light can be performed even at the periphery of the wafer, and a modified region by multi-photon absorption can be formed at a predetermined position inside the wafer.