Method for laser-assisted bonding, substrates bonded in this manner and use thereof
The present invention relates to a method for laser-assisted bonding of substrates, in which these are connected together firstly frictionally by pressing together and subsequently strengthening of the connection between the substrates is effected by activation in regions which is induced by laser irradiation. The invention likewise relates to substrates produced accordingly.
1. A method for laser-assisted bonding of substrates, in which two substrates are connected together by being brought in direct contact and strengthening of the connection between the substrates is effected subsequently by activation in regions which is induced with laser irradiation at an interface between the substrates, the melting or transformation temperature of the substrates not being reached during the activation, wherein a chemical excitation of the molecules and/or atoms of at least one substrate is effected in the region of the interface by means of the laser irradiation, wherein the two substrates are essentially transparent for a radiated laser irradiation with a wavelength λ a , and are irradiated with laser irradiation of a longwave, non-linearly absorbing wavelength, and multiphoton processes are initiated by precise focusing with correspondingly high intensity of the laser irradiation and an activation energy and hence a degree of strengthening of the connection is adjusted via focusing, wavelength, pulse duration, pulse energy, pulse repetition rate and a number of pulses of the laser irradiation.
2. The method according to claim 1 , wherein the substrates are amorphous, partly crystalline and/or crystalline.
3. The method according to claim 2 , wherein the substrates are amorphous and are selected from a group consisting of glasses.
4. The method according to claim 3 , wherein the amorphous substrates are comprised of silicon dioxide.
5. The method according to claim 3 , wherein glass ceramics are used as partly crystalline substrates.
6. The method according to claim 3 , wherein semiconductors, ceramics, piezoceramics and/or non-linear optical crystals are used as crystalline substrates.
7. The method according to claim 1 , wherein the laser irradiation is focused on the interface between the substrates.
8. The method according to claim 7 , wherein the wavelength of the laser irradiation is coordinated to at least one substrate and a focusing of the laser irradiation is chosen such that excitation of bonding conditions of the molecules and/or atoms of at least one substrate is effected specifically in the region of the interface and an activation energy and hence a degree of strengthening of the connection is adjusted via focusing, pulse energy, pulse repetition rate and a number of pulses of the laser irradiation.
9. The method according to claim 1 , wherein the substrates are selected from a group consisting of plastic materials.
10. The method according to claim 9 , wherein the plastic materials are selected from a group consisting of polymethylmethacrylate, polycarbonate, polymers and copolymers of cycloolefins, and composite materials thereof.
11. The method according to claim 1 , wherein two different substrates are used.
12. The method according to claim 11 , wherein the substrates have a different thermal coefficient of expansion.
13. The method according to claim 1 , wherein additionally a thermal excitation of the molecules and/or atoms of the at least one substrate is effected in the region of the interface by means of the laser irradiation and/or diffusion processes are initiated in at least one substrate in the region of the interface.
14. The method according to claim 1 , wherein the laser irradiation is pulsed.
15. The method according to claim 1 , wherein two substrates made of the same material are used.
16. The method according to claim 1 , wherein the substrates are connected together frictionally by pressing together.
17. The method according to claim 1 , wherein the laser activation is implemented in a protective gas atmosphere or in a vacuum.
18. The method according to claim 1 , wherein the surfaces of the substrates to be connected are cleaned in advance.
19. The method according to claim 1 , wherein a plasma activation of the surfaces of the substrates to be connected is effected in advance.
20. The method according to claim 1 , wherein functionalisation of the surfaces of the substrates to be connected is effected in advance.
21. The method according to claim 1 , wherein linear or planiform strengthening are effected by means of activation of adjacent regions.
22. The method according to claim 1 , wherein the bonding is effected by direct bonding with the process steps cleaning, plasma activation and pressing together.
23. The method according to claim 1 , wherein all the method steps are implemented in the same unit.