Lift-off method and laser machining apparatus

Abstract

The invention provides a lift-off method and a laser processing apparatus which are capable of achieving desired processed results and preventing a reduction in the quality of processed products. A lift-off method includes a relocation substrate joining step of joining a relocation substrate to a surface of an optical device layer of an optical device wafer with a joining member interposed therebetween, thereby forming a composite substrate, a buffer layer breaking step of applying a pulsed laser beam having a wavelength transmittable through an epitaxy substrate and absorbable by a buffer layer to the buffer layer from a reverse side of the epitaxy substrate of the optical device wafer of the composite substrate, thereby breaking the buffer layer, and an optical device layer relocating step of peeling off the epitaxy substrate from the optical device layer, thereby relocating the optical device layer to the relocation substrate. In the buffer layer breaking step, irradiating conditions of the pulsed la-ser beam are changed for respective ring-shaped areas of the buffer layer, and the pulsed laser beam is applied to the optical device wafer under the changed irradiating conditions.

Description

technical field [0001] The present invention relates to a lift off method and a laser processing device. Background technique [0002] The following lift-off method is used: the optical device layer of the optical device wafer on which the optical device layer is laminated on the front surface of the epitaxial substrate with the buffer layer interposed is bonded to the transfer substrate with the bonding material, and the optical device wafer and the transfer substrate are bonded to the optical device wafer and the transfer substrate with The buffer layer of the composite substrate formed by bonding the bonding material is irradiated with a laser beam to destroy the buffer layer, and transfer the optical device layer from the epitaxial substrate to the transfer substrate (for example, refer to Patent Document 1). [0003] Patent Document 1: Japanese Patent Laid-Open No. 2013-229386 [0004] However, in the lift-off method of separating the composite substrate by irradiating...

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Problems solved by technology

[0004] However, in the lift-off method of separating the composite substrate by irradiating a laser beam described in Patent Document 1, the composite substrate has warpage caused by bonding the optical device wafer to the transfer substrate or the like.

[0005] When such a composite substrate is irradiated with a laser beam, since the irradiation method (concentration state) of the laser beam is different between the outer peripheral part and the central part, there may be cases where only the outer peripheral part is peeled first and the central part is not peeled off or vice versa. The problem that the expected processing result cannot be obtained due to the phenomenon

[0006] Furthermore, when the entire composite substrate is additionally irradiated with a laser beam in order to promote the delamination of the non-delaminated region, there is a problem that not only the processing time becomes longer, but also the delaminated part is damaged and the quality deteriorates.

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