High Speed Handling of Ultra-Small Chips by Selective Laser Bonding and Debonding

Abstract

Techniques for high speed handling of ultra-small chips (e.g., micro-chips) by selective laser bonding and / or debonding are provided. In one aspect, a method includes: providing a first wafer including chips bonded to a surface thereof; contacting the first wafer with a second wafer, the second wafer including a substrate bonded to a surface thereof, wherein the contacting aligns individual chips with bonding sites on the substrate; and debonding the individual chips from the first wafer using a debonding laser having a small spot size of about 0.5 μm to about 100 μm, and ranges therebetween. A system is also provided that has digital cameras, a motorized XYZ-axis stage, and a computer control system configured to i) control a spot size of the at least one laser source and ii) adjust a positioning of the sample to align individual chips with a target area of the laser.

Description

FIELD OF THE INVENTION[0001]The present invention relates to chip handling techniques, and more particularly, to high speed handling of ultra-small chips (e.g., micro-chips) by selective laser bonding and / or debonding.BACKGROUND OF THE INVENTION[0002]During fan-out wafer-level packaging (FOWLP), individual chips are precisely placed on a (reconstituted) thin wafer substrate. A mold is formed over the reconstituted wafer substrate, followed by a redistribution layer (RDL) and a solder layer.[0003]Pick-and-place machines operate by placing electronic components (such as chips, capacitors, resistors, etc.) sequentially, one after another, onto a substrate. With high-speed auto alignment and positioning equipment, a pick-and-place machine can efficiently achieve reconstituted wafers with chip sizes of 10× millimeters (mm) in minutes. However, with micro-chip components (e.g., chip size of only 10× micrometers (μm)), it can take hundreds of hours to get a reconstituted 12-inch wafer via ...

AI Technical Summary

Benefits of technology

The present invention provides a method and system for high-speed handling of ultra-small chips by selective laser bonding and / or debonding technology in wafer-level processes. The method includes aligning individual chips with bonding sites on a substrate, and then debonding the individual chips from the first wafer using a small spot size of a debonding laser. The system includes an optical scanner, a laser source, digital cameras, a motorized XYZ-axis stage, and a computer control system for adjusting the position of the motorized XYZ-axis stage to align individual chips with a target area of the laser source. The technical effect of the invention is improved efficiency and accuracy in handling small chips during wafer-level processes.

Problems solved by technology

However, with micro-chip components (e.g., chip size of only 10× micrometers (μm)), it can take hundreds of hours to get a reconstituted 12-inch wafer via pick-and-place processing.

Further, high placement accuracy is always desired in wafer reconstitution, which makes the process even slower.

Thus, the wafer reconstitution process for micro-chips is time-consuming, affecting the throughput and cost performance of the fan-out package.

However, due to the ultra-small sizes and reduced thicknesses of micro-chip components, it is a challenge to provision a suitable vacuum nozzle for reliable assembly.

Namely, once chips are less than 300 micrometers (μm), handling and stiction can become a problem due to the gravitational force as compared to the surface forces.

Further, the down-force of the nozzle can easily crack thin chips during placement on the substrate.

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