Photomagnetic Micro LED Transfer for Heat-Free Wafer Reuse

The patent replaces the laser-based thermal separation mechanism with a magnetic field-based separation mechanism. The photomagnetic substrate generates magnetic fields to attract and hold micro LED chips during transfer, then releases them without thermal damage. This substitutes the harmful thermal-mechanical separation process with a non-contact magnetic field-based process, eliminating laser and heat damage while maintaining mass transfer capability

The patent changes the physical state and properties of the photomagnetic substrate by controlling light exposure. When exposed to light, the photomagnetic material transitions to a magnetically active state to attract chips; when light is removed, it returns to a non-magnetic state to release chips. This parameter change (magnetic field presence/absence) enables controlled chip attachment and release without thermal damage, solving the contradiction between effective transfer and substrate protection

The patent enables recovery and reuse of the transfer substrate by replacing permanent adhesive methods with reversible magnetic field-based attachment. The photomagnetic substrate can be repeatedly activated with light to attract chips and then deactivated to release chips, allowing the same substrate to be used for multiple transfer cycles. This recovers the substrate value that would otherwise be lost in conventional single-use transfer methods

The photomagnetic substrate serves itself by using light exposure to automatically activate magnetic fields for chip attraction and light removal to automatically deactivate for chip release. This self-controlled magnetic field generation and cancellation eliminates the need for additional mechanical or chemical release mechanisms, enabling repeated use of the same substrate without degradation, thus improving both transfer efficiency and substrate reusability