A method and device for processing LED chips on sapphire substrates

Abstract

The invention relates to the field of chip laser processing, and specifically discloses a method and device for processing a sapphire substrate LED chip. In the processing method proposed by the invention, a relatively shallow initial crack is first generated by scribing on the surface of the LED wafer, and then the initial crack is Heating and cooling at the place to make it generate stress, and then apply impact pressure to the initial crack along the direction perpendicular to the mirror surface of the LED wafer, and crush the LED wafer along the initial crack, so that the side surface of the LED wafer after fracturing can be achieved. It is smooth and mirror-like, and at the same time, the laser scribing depth is shallow, so that the depth of the reformed layer is shallow. The processing device proposed by the present invention can realize simultaneous laser scribing, heating and cooling treatments on the LED wafer. The airflow can discharge the molten material generated by laser scribing from the initial crack, avoiding bonding in the initial crack, and can also perform fracturing treatment on the LED wafer along the initial crack, and the fracturing spacing is consistent with the spacing between the initial cracks ,High precision.

Description

technical field [0001] The invention relates to the field of chip laser processing, in particular to a method and a device for processing a sapphire substrate LED chip. Background technique [0002] In recent years, sapphire substrate LED chips have been developing rapidly due to their advantages such as low energy consumption, high luminous efficiency, long life, green environmental protection, cold light source, fast response time, and can be used under various harsh conditions. A new generation of lighting sources. With the maturity of III-V semiconductor technology, the development of LED chips continues to develop in the direction of higher efficiency and higher brightness. As its application becomes more and more extensive, how to improve the luminous efficiency of GaN-based LEDs has increasingly become the focus of attention. The main factors affecting the luminous efficiency of LEDs are internal quantum efficiency and external quantum efficiency, and the improvement...

AI Technical Summary

Problems solved by technology

[0009] Generally, single-spot implicit cutting can only be aimed at relatively thin LED wafers with a thickness of 80-150um. Focusing and scribing at a position 1 / 3 from the surface forms a modified layer, and then separates them by film expansion or mechanical splitting. Although The glue coating process is avoided, but this method cannot process thicker LED wafers, because the depth of the single-spot modified layer is generally 10-80um, the crack tendency is limited, and it is easy to cause oblique cracks or even twin crystal problems when mechanically split

[0010] Multi-spot implicit cutting, the overall cutting depth is often greater than 1 / 2 of the chip thickness. Although the processing efficiency is improved and the depth of the modified layer is increased, the film can be separated without mechanical splitting, and the problem of oblique cracking and twin crystals is avoided. , but the increase of the modified layer on the side of the LED wafer also means that the area that destroys the sapphire lattice structure increases accordingly, which affects the luminous efficiency of the LED and is prone to chip leakage

[0011] Whether it is surface cutting or stealth cutting, both of them are directly stripped or modified by laser on the LED chip, and the width of the modified layer is often close to 1 / 3-1 / 2 of the thickness of the LED chip or larger, even if the process is optimized parameters to reduce sputtering, collapse, oblique cracks, double crystals, etc., but because the essence of LED wafer chips is to emit light and be durable, a deeper modified layer not only affects the luminous efficiency, but also reduces the quality of a single LED chip. In later use, due to the heating of the LED chip, it is more likely to cause micro-cracks to expand, thereby shortening the service life of the LED chip

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