US-12622221-B2 - Method for the separation of structures from a substrate

US12622221B2US 12622221 B2US12622221 B2US 12622221B2US-12622221-B2

Abstract

A method and a device for the separation of structures from a substrate. Furthermore, the invention relates to a method and a device for transferring structures from a first substrate to a second substrate.

Inventors

Boris Povazay
Venkata Raghavendra Subrahmanya Sarma Mokkapati

Assignees

EV GROUP E. THALLNER GMBH

Dates

Publication Date: 20260505
Application Date: 20210330

Claims (14)

1 . A method for separating structures from a substrate, the method comprising: i) growing a thin layer on a first substrate; ii) forming at least one structure from the thin layer; iii) coating the at least one structure; iv) contacting a second substrate with the at least one structure, the coating being between the second substrate and the at least one structure; v) irradiating of a boundary area between the first substrate and the at least one structure with electromagnetic radiation; and vi) separating the at least one structure from the first substrate, wherein the electromagnetic radiation first penetrates the at least one structure and then strikes the boundary area.
2 . The method according to claim 1 , wherein the separation of the at least one structure takes place selectively.
3 . The method according to claim 1 , wherein the at least one structure has a thickness between 0 μm and 1000 μm.
4 . The method according to claim 1 , wherein the at least one structure is generated on the first substrate before the separation.
5 . The method according to claim 1 , wherein, during the irradiation in step v), the electromagnetic radiation is emitted by irradiation means and directed onto the at least one structure.
6 . The method according to claim 1 , wherein the first substrate is made of silicon.
7 . The method according to claim 1 , wherein the at least one structure is made of gallium nitride (GaN).
8 . The method according to claim 1 , wherein a wavelength of the electromagnetic radiation lies between 300 nm and 2000 nm.
9 . The method according to claim 1 , wherein a transmissivity of the at least one structure for electromagnetic radiation is greater than 10%.
10 . The method according to claim 1 , wherein a transmissivity of the first substrate for electromagnetic radiation is less than 90%.
11 . The method according to claim 1 , wherein an intensity of the electromagnetic radiation lies between 100 mWatt and 10 kWatt.
12 . A device for separating at least one structure from a first substrate, the at least one structure being in contact with a second substrate, said device comprising: irradiation means for irradiating, through the second substrate, a boundary area between the first substrate and the at least one structure with electromagnetic radiation; and separation means for separating the at least one structure from the first substrate, wherein the irradiation means are constituted such that the electromagnetic radiation first penetrates the at least one structure and then strikes the boundary area.
13 . The method according to claim 1 , wherein the second substrate is transparent for electromagnetic radiation and is arranged between an irradiation means and the at least one structure during the irradiating of the boundary area.
14 . The method according to claim 1 , wherein the at least one structure includes an electronic component.

Description

FIELD OF INVENTION The present invention relates to a method and a device for the separation of structures from a substrate. Furthermore, the invention relates to a method and a device for transferring structures from a first substrate to a second substrate. The structures to be separated from the substrate are in particular components split up into single units from a thin layer or the thin layer as such. The thin layer or the structures split up into single units have been produced in particular on the substrate, preferably grown on the substrate. The thin layer and the structures will thus be used synonymously in the following text. The structure to be separated is therefore disclosed in each case in connection with a structure split into single units or a thin layer. BACKGROUND OF INVENTION The prior art deals with the ablation of thin layers or structures split up into single units from a substrate with the aid of electromagnetic radiation. Thus, it is common for a laser to act on a boundary area in particular from a rear side of a substrate transparent for electromagnetic radiation, in order to bring about a detachment of the thin layer from this substrate. Radiation does not pass through the thin layer, but rather radiation takes place from the side of the substrate on which the thin layer is fixed. This process is referred to as the laser lift off (LLO) process in the prior art. An LLO process is a contactless process wherein the thin to ultrathin layers can be separated from a substrate, in particular from a growth substrate. One of the prerequisites for a separation is that the substrate is transparent for the laser radiation used. Furthermore, provision is often made in the prior art such that an absorbing layer is provided between the substrate and the thin layer, so that the detachment takes place by the laser acting on the so-called detachment layer. The laser radiation is first passed from the rear side of the substrate through the substrate and then strikes the detachment layer or the thin layer. As a result of the interaction of the laser radiation with the absorbing layer, an ablation takes place through a physical and/or chemical reaction. Photochemical, photothermal or combined separating processes for example are conceivable. It is also conceivable that the thin layer itself has a high absorption capacity for laser radiation and an absorbing layer is dispensed with. In this case, the processes take place in a boundary area or an interface of the substrate and the thin layer. Furthermore, plasma is very often used in order to improve the detachment of the thin layer from the substrate. The adhesive forces between the substrate and the thin layer are markedly weakened by the aforementioned approach. In particular, a gas formation between the substrate and the thin layer contributes to a weakening of the adhesive forces. Gas arises primarily with the use of an additional absorbing layer between the substrate and the thin layer. In the case of LLO processes, the transparency properties of the substrate and the absorption properties of the interface between the substrate and of the thin layer or the thin layer itself are typically used. An example in the prior art is the gallium nitride/sapphire system. The very thin gallium nitride (GaN) layer is grown on a sapphire substrate. The ablation takes place with UV radiation. In this system, GaN absorbs the UV radiation used very intensively, whilst the sapphire substrate is very transparent in this wavelength region. Furthermore, the photochemical reaction 2GaN→2GaN+N2 takes place, wherein nitrogen gas arises, which promotes the ablation by its volume expansion. The higher absorption and reflectivity of pure, metallic gallium, which arises through the chemical reaction at the interface, further supports the process. The laser interaction of matter takes place in particular via the electrons. In rare cases, resonances permit a direct interaction with bound states. Laser radiation with an exact energy is required for this. Virtually free electrons in metals, i.e. electrons which are intensely subjected only to the prevailing potential, can be used as highly efficient broadband absorbers, in order to absorb laser radiation. Epitaxially grown GaN layers have a band gap of 3.3 eV, whereas the band gap of sapphire lies at approx. 9.9 eV. For an LLO process with GaN on sapphire, a UV laser can for example be used in order to penetrate the sapphire substrate and to interact with the GaN or the GaN-sapphire interface. Such thin layers, for example GaN layers, are usually produced on a growth substrate, which has a very low transmissivity for the electromagnetic radiation used, which is intended to be used for the ablation. The growth substrate thus absorbs the electromagnetic radiation and the latter does not pass into the boundary area or reach the interface between the thin layer and the growth substrate, so that a separation of the thin layer is not