Separation of thin films from transparent substrates by selective optical processing
First Claim
1. A method of separating a thin film from a growth substrate, comprising the steps of:
- growing a film of a first composition on a first side of a crystallographically oriented first substrate of a second composition, wherein said film comprises a III-V nitride compound and said first substrate comprises sapphire;
bonding said film on a side thereof opposite said first substrate to a second substrate;
irradiating said first substrate from an irradiation side thereof with light of a wavelength that is substantially more strongly absorbed in said film than in the one of said first and second substrates on said irradiation side of said film, wherein said irradiating step forms an interfacial layer between said film and said first substrate; and
after completion of said irradiating step, detaching said second substrate with portions of said film attached thereto from said first substrate, wherein said detaching step severs said interfacial layer.
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Abstract
A method of separating a thin film of GaN epitaxially grown on a sapphire substrate. The thin film is bonded to an acceptor substrate, and the sapphire substrate is laser irradiated with a scanned beam at a wavelength at which sapphire is transparent but the GaN is strongly absorbing, e.g., 248 nm. After the laser irradiation, the sample is heated above the melting point of gallium, i.e., above 30° C., and the acceptor substrate and attached GaN thin film are removed from the sapphire growth substrate. If the acceptor substrate is flexible, the GaN thin film can be scribed along cleavage planes of the GaN, and, when the flexible substrate is bent, the GaN film cleaves on those planes. Thereby, GaN lasers and other electronic and opto-electronic devices can be formed.
988 Citations
25 Claims
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1. A method of separating a thin film from a growth substrate, comprising the steps of:
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growing a film of a first composition on a first side of a crystallographically oriented first substrate of a second composition, wherein said film comprises a III-V nitride compound and said first substrate comprises sapphire; bonding said film on a side thereof opposite said first substrate to a second substrate; irradiating said first substrate from an irradiation side thereof with light of a wavelength that is substantially more strongly absorbed in said film than in the one of said first and second substrates on said irradiation side of said film, wherein said irradiating step forms an interfacial layer between said film and said first substrate; and after completion of said irradiating step, detaching said second substrate with portions of said film attached thereto from said first substrate, wherein said detaching step severs said interfacial layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A method of separating a thin film from a growth substrate, comprising the steps of:
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growing a film of a first composition on a first side of a crystallographically oriented first substrate of a second composition, wherein said film comprises GaN; bonding said film on a side thereof opposite said first substrate to a second substrate; irradiating said first substrate from a second side thereof with light of a wavelength that is substantially more strongly absorbed in said film than in said first substrate, said irradiating step producing an interfacial layer between said first substrate and said film and not causing said second substrate to separate from said first substrate; and after completion of said irradiating step, detaching said second substrate with portions of said film attached thereto from said first substrate. - View Dependent Claims (25)
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Specification